Sports Injury Prevention This Page Intentionally Left Blank Handbook of Sports Medicine and Science Sports Injury Prevention

Handbook of Sports Medicine and Science Sports Injury Prevention This page intentionally left blank Handbook of Sports Medicine and Science Sports Injury Prevention

EDITED BY Roald Bahr MD, PhD

Department of Sports Medicine and Oslo Sports Trauma Research Center Norwegian School of Sport Sciences Ullevål Stadion, Oslo, Norway

Lars Engebretsen MD, PhD

Orthopaedic Center Ullevaal University Hospital and Faculty of Medicine University of Oslo Oslo, Norway Department of Sports Medicine and Oslo Sports Trauma Research Center Norwegian School of Sport Sciences Ullevål Stadion Oslo, Norway

Published by Blackwell Publishing Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing program has been merged with Wiley’s global Scientifi c, Technical and Medical business to form Wiley-Blackwell. Registered offi ce: John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offi ces: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ 07030-5774, USA

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1 2009 Contents

List of Contributors, vi 8 Preventing low back pain 114 Foreword, viii Adad Baranto, Tor Inge Andersen and Preface, ix Leif Swärd

1 Why is injury prevention in sports 9 Preventing shoulder injuries 134 important? 1 Michael R. Krogsgaard, Marc R. Safran, Lars Engebretsen and Roald Bahr Peter Rheinlænder and Emilie Cheung

2 A systematic approach to sports 10 Preventing elbow injuries 153 injury prevention 7 Mark R. Hutchinson and James R. Andrews Willem Meeuwisse and Roald Bahr 11 Preventing injuries to the head and 3 Developing and managing an injury cervical spine 175 prevention program within the team 17 Paul McCrory, Michael Turner and Andrew McIntosh and Roald Bahr Andrew McIntosh

4 Preventing ankle injuries 30 12 Preventing tendon overuse injuries 187 Jon Karlsson, Evert Verhagen, Jill Cook, Mads Kongsgaard, Bruce D. Beynnon and Annunziato Amendola Karim Khan and Michael Kjær

5 Preventing knee injuries 49 13 Implementing large-scale injury Timothy E. Hewett, Bruce D. Beynnon, prevention programs 197 Tron Krosshaug and Grethe Myklebust Randall W. Dick, Claude Goulet and Simon Gianotti 6 Preventing hamstring injuries 72 Geoffrey M. Verrall and Árni Árnason, 14 Planning for major events 212 Kim Bennell Michael Turner and Jiri Dvorak

7 Preventing groin injuries 91 Index, 228 Per Hölmich, Lorrie Maffey and Carolyn Emery

v List of Contributors

Annunziato Amendola MD Jill Cook PhD, B App Sci (Phty) Department of Orthopaedic Surgery and Centre for Physical Activity and Nutrition Research Rehabilitation, University of Iowa Sports Medicine School of Exercise and Nutrition Sciences, Deakin Center, University of Iowa, Iowa City, IA, USA University, Melbourne, Australia

PT Tor Inge Andersen Randall W. Dick MS, MS National Center of Spinal Disorders, National Center Research/Injury Surveillance System National of Pain and Complex Disorders, Trandheim University Collegiate Athletic Association, Indianapolis, Hospital, St Olar, Norway IN, USA James R. Andrews, MD Medical Director, American Sports Medicine Institute, Jiri Dvorak MD Birmingham, Alabama, USA; Andrews Sports FIFA Medical Assessment and Research Center Medicine Institute, Gulf Breeze, FL, USA (F-MARC), Schulthess Clinic, Zurich, Switzerland

Árni Árnason PT, PhD Carolyn Emery BScPT, PhD Department of Physiotherapy, University of Iceland, Sport Medicine Centre, Faculty of Kinesiology; Reykjavik, Iceland Community Health Sciences, Faculty of Medicine, Roald Bahr MD, PhD University of Calgary, Calgary, Canada Department of Sports Medicine, Oslo Sports Trauma Research Center, Norwegian School of Sport Sciences, Lars Engebretsen MD, PhD Ullevål Stadion, Oslo, Norway Orthopaedic Center, Ullevaal University Hospital and Faculty of Medicine, University of Oslo, Oslo, Norway; Adad Baranto MD, PhD Department of Sports Medicine and Oslo Sports Department of Orthopaedics, Sahlgrenska University, Trauma Research Center, Norwegian School of Sport Göteborg, Sweden Sciences, Ullevål Stadion, Oslo, Norway Kim Bennell BAppSc (Physio), PhD Centre for Health, Exercise and Sports Medicine, Simon Gianotti BCA School of Physiotherapy, University of Melbourne, Institute of Sport and Recreation Research New Australia Zealand, Faculty of Health and Environmental Science, AUT, Auckland, New Zealand Bruce D. Beynnon PhD Department of Orthopaedics and Rehabilitation, Claude Goulet PhD McClure Musculoskeletal Research Center, Department of Physical Education, Laval University, The University of Vermont, VT, USA Québec, Canada vi List of Contributors vii

Timothy E. Hewett PhD Paul McCrory MBBS, PhD The Human Performance Laboratory, Departments Centre for Health, Exercise and Sports Medicine, of Pediatrics, Orthopaedic Surgery, Biomedical University of Melbourne Parkville, Australia Engineering and Rehabilitation Sciences, The Sports Medicine Biodynamics Center, Cincinnati Children’s Andrew McIntosh PhD, MBiomedE, Hospital Medical Center, University of Cincinnati BAppSci (PT) College of Medicine, Cincinnati, OH, USA School of Risk and Safety Sciences, The University of New South Wales, Sydney, Australia Per Hölmich MD Department of Orthopaedic Surgery, Orthopaedic Willem Meeuwisse MD, PhD Research Unit, Amager University Hospital, Professor and Chair, Copenhagen S, Denmark Sport Injury Prevention Research Centre Faculty of Kinesiology and Faculty of Medicine, Mark R. Hutchinson MD University of Calgary, Department of Orthopaedics, University of Illinois at Alberta, Canada Chicago, IL, USA Grethe Myklebust PT, PhD Jon Karlsson MD, PhD Oslo Sports Trauma Research Center, Norwegian School Professor of Sports Traumatology, Department of of Sport Sciences, Oslo, Norway Orthopaedics, Sahlgrenska University Hospital, Göteborg, Sweden Peter Rhein legature Clinic for Physiotherapy, Frederiksberg, Denmark Karim Khan MD, PhD Professor, Center for Hip Health and Mobility, Marc R. Safran MD University of British Columbia, Vancouver, Canada Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA Michael Kjær MD, DMSci MD PhD Department of Rheumatology, Institute of Sports Leif Swärd , Medicine, Bispebjerg Hospital, University of Department of Orthopaedics, Sahlgrenska University, Copenhagen, Copenhagen, Denmark Göteborg, Sweden MBBS, MD Michael R. Krogsgaard, MD, PhD, Michael Turner Chief Medical Adviser, The British Associate Professor, specialist in Orthopaedic Horseracing Authority and Lawn Surgery Tennis Association; formerly CMA to Department of Orthopaedic Surgery, Copenhagen British Olympic Association and University Hospital Bispebjerg, Denmark Snowsport, UK

Tron Krosshaug PhD Evert Verhagen Oslo Sports Trauma Research Center, Norwegian School Department of Public and Occupational Health, EMG of Sport Sciences, Oslo, Norway Institute, VU University Medical Center, Amsterdam, The Netherlands Lorrie Maffey BMRPT, Dip Faculty of Kinesiology; Community Health Sciences, Geoffrey M. Verrall MBBS Faculty of Medicine, University of Calgary, Calgary, Sports Medicine Clinic, Adelaide, Australia Alberta, Canada Foreword

The objective established in 1991 by the IOC of injuries and their prevention became one of the Medical Commission for the Handbook series was focuses of the Medical Commission and the Medical the presentation in a clear style and format of and Scientifi c Department of the IOC. basic clinical and scientifi c information regarding The principal objective of this Handbook on the sports of the Olympic Summer Games and the Sports Injury Prevention is a comprehensive review Olympic Winter Games. Each of the handbooks of the information currently available regarding that have been published during the intervening the identifi cation of the risk factors for specifi c years was developed by a team of authorities coor- injuries in each sport, the understanding of the dinated by editors who had earned international injury mechanisms, the appropriate condition- respect and recognition in the areas of sports med- ing of athletes for the particular sport, and the risk icine and the sport sciences. management appropriate to each activity. Since the appearance of the fi rst publication, The Handbook on Sports Injury Prevention handbooks have appeared that have dealt with constitutes the most comprehensive review of 10 Olympic sports as well as the general top- the preclusion of the occurrence of injuries pres- ics of strength training and nutrition for ath- ently available and each section presents highly letes. Sections dealing with sports injuries have practical information based on published science. appeared throughout these handbooks. Two vol- We welcome this splendid contribution by Roald umes of the other IOC Medical Commission series, Bahr, MD, PhD, Lars Engebretsen, MD, PhD, and Encyclopaedia of Sports Medicine, have been 36 contributing authors to the literature of sports devoted completely to injuries in sport. medicine and sports science. The protection of the health of the athletes is one of the IOC’s priorities. Therefore, the understanding

viii Preface

In sports, injuries happen. Sometimes they happen tive programs. Chapter 3 describes how an injury by chance, sometimes by intent. Sometimes they prevention program can be developed and imple- are diffi cult, even impossible, to explain. But fre- mented within the team. In this context, a team quently there are clear patterns. And when there can also mean a team of athletes competing in are patterns, there are also opportunities for reduc- individual sports, such as a team of alpine skiers. ing the risk of injury. One choice we faced when planning this book, The objective of this book is to describe those was whether to organize the contents per sport opportunities – for the benefi t of everyone playing or per body part/injury type. One advantage sports. Although it may be expected that the main of describing sports-specifi c programs is that it readership will be physicians, trainers and physical would be possible to detail measures particular to therapists working with sports teams, the coach- that sport, for example equipment-related meas- ing staff is an even more important target group. ures such as alpine ski bindings. However, partly And although it is assumed that the reader has a because some such information is available already basic knowledge of human anatomy and physiol- (e.g. vol. V of the Encyclopedia of Sports Medicine ogy, ultimately the main audience is of course the series: Clinical Practice of Sports Injury Prevention athlete. With these target groups in mind, we have and Care, ed. P.A.F.H. Renström), we felt that a attempted to create a work that is at once com- region-specifi c approach would be more appro- prehensive in approach, practical in content, and priate. Chapters 4 through 12 therefore describes accessible in delivery. how the most common sports injury types can Our intention is to describe a practical approach be prevented; ankle, knee, hamstring, groin, low to the prevention of sports injuries. The fi rst three back, shoulder, elbow, head and cervical spine chapters describe the general principles of injury injuries. The fi nal two chapters discusses how prevention. Chapter 1 discusses why injury preven- tendon overuse injuries, which represent a major tion in sports is important, including perspectives problem across sports and body region, can be pre- on short- and long term consequences for health vented (ch. 12) and how large-scale injury preven- and performance. Chapter 2 describes the basis tion programs can be implemented (ch. 13). for intervention, how information on risk factors Each of the region-specifi c chapters includes an and injury mechanisms can be used to identify introduction outlining how relevant each injury patterns. Such patterns can be used to identify type is in each of the main Olympic sports. In con- athletes with a higher risk for injury or situations trast to previous works on sports injury epidemiol- with a propensity for injury; information which ogy, we have attempted to keep this section brief is critical to be able to target and develop preven- and to the point, answering the key questions:

ix x Preface

How common is the injury in question? What is section of each of these chapters is the section on the risk – in my sport? The next section attempts prevention methods. This section discusses pos- to describe the key risk factors for the injury in sible ways to prevent the injury in question, and question – how to identify athletes at risk. This although these may be relevant across sports, the includes a description of the various internal and text provides examples from sports where injury external risk factors suggested for the injury in prevention has been successful. We have tried to question, emphasizing modifi able risk factors and make this section as practical as possible, with how the coach/medical team can identify play- examples of take-home ready-to-use programs ers at risk of injury. In some cases, simple tests or wherever possible, complete with illustrations of screening methods which can be applied to a team exercises used. setting are described. This section is followed by a This book is the fi rst of its kind. Never before has description of the typical injury mechanisms for anyone attempted to provide a guide to injury pre- the injury in question, not just the biomechan- vention – to be applied across different sports. This ics of injury, but also the circumstances leading to represents a signifi cant challenge, since there is no injury, such as player behavior, opponent behav- model available to guide us in the development ior, the playing situation, or other relevant factors. of the contents. We wish to thank the authors, We have also asked all authors to provide a section who have worked hard to not just provide an up- identifying risks in the training and competition to-date description of injury prevention methods program, a risk analysis to document the parts of relevant to their region and injury type, but also the season when athletes are at the greatest risk to develop a text consistent in content and format for sustaining injuries as a result of the training or across the various chapters. If we have succeeded, competitive programs. For some injury types, this the credit belongs to this group of dedicated pro- type of analysis could be an important basis for fessionals. If not, the responsibility is ours. planning preventive measures, particularly for the purpose of avoiding overuse injuries during tran- Oslo, September 2008 sitional periods. The fi nal – and most important – Roald Bahr & Lars Engebretsen Chapter 1 Why is injury prevention in sports important? Lars Engebretsen1 and Roald Bahr2

1Orthopaedic Center, Ullevaal University Hospital and Faculty of Medicine, University of Oslo, Oslo, Norway 2 Department of Sports Medicine, Oslo Sports Trauma Research Center, Norwegian School of Sport Sciences, Ullevål Stadion, Oslo, Norway

This book is a result of the IOC Medical Commis- see if there is suffi cient merit in sports injury pre- sion’s increasing emphasis on prevention of sports vention research. injuries. The numerous health benefi ts of physical activity have been well documented, resulting in public health support of regular physical Is injury prevention important? activity and exercise. Although benefi cial, exercise and sports also have corresponding risks, including that of musculoskeletal injuries. However, at First, is injury prevention important? Epidemiologi- a time when there is an abundance of medical cal studies show that of injuries seen by a physi- meetings, journals, and papers, some might argue cian, in Scandinavia, every sixth is sustained that the last thing we need is a new book focus- during sporting activity (Bahr et al., 2002). Among ing on yet another fi eld of research and clinical children, every third hospital-treated injury is the practice. What would justify such an emphasis result of sports participation (Bahr et al., 2002). on a new and developing fi eld in medicine? First, During 1997 and 1998, in the United States, annu- it must ask important questions not answered ally there were an estimated 3.7 million sports- and by others. Second, the new research fi eld should recreation-related emergency department visits have the potential to create truly new knowledge, annually in the United States, representing approx- lead to new ways of thinking and lay the founda- imately 11% of all injury related emergency depart- tion for improved health for our patients. This is ment visits; 2.6 million visits were among persons usually not possible without a multidisciplinary aged 5–24 years. The medical charges for these vis- approach, involving a mixture of basic scientists its were estimated at 500 million US$ annually. and clinicians. Third, research results from the new The risk of injury clearly differs between sports, fi eld should be publishable in respected journals, as documented by a study initiated by the IOC recognized and cited by peers, presentable at high- Medical Commission in team sports during the quality meetings, and fundable on competitive 2004 Olympic Games in Athens (Junge et al., grant review. Let us examine each of these issues to 2006). As shown in Table 1.1, while a soccer and handball player suffered one injury every 10th match he or she play, a volleyball player at the elite level only had an injury every 100th match on the Sports Injury Prevention, 1st edition. Edited by R. Bahr and average. Not all of these injuries are serious; in fact L. Engebretsen Published 2009 by Blackwell Publishing ISBN: 9781405162449 only about half of all the injuries recorded were

1 2 Chapter 1

Table 1.1 Injury risk in selected team sports during the boarders with an 8% mortality rate among those 2004 Olympic Games in Athens. admitted to hospital with head injuries. Among Sport Total injury rate1 Rate of time-loss injuries related to football, 4–22% are head injuries. injuries2 The reported incidence during matches—1.7 injuries per 1000 player hours—incorporates all types Football of head injuries including facial fractures, contu- Men 109 (85–133) 44 (29–60) Women 105 (74–136) 44 (24–64) sions, lacerations, and eye injuries (Andersen et al., Handball 2004). The estimated incidence of concussion— Men 89 (64–114) 40 (23–57) 0.5 injuries per 1000 match hours—probably repre- Women 145 (110–180) 36 (18–53) sents a minimum estimate due to the problem of Basketball defi ning and grading concussions (Andersen et al., Men 64 (40–89) 29 (12–45) Womenv 67 (42–91) 24 (9–39) 2004). Although most athletes with head injuries Field hockey recover uneventfully following a single concus- Men 55 (37–72) 24 (12–36) sive episode, repetitive mild head trauma may be Women 17 (5–29) 4 (0–10) implicated in the development of cumulative cog- Baseball (men) 29 (15–43) 13 (3.2–22) nitive deterioration. Based on paper and pencil Water polo (men) 30 (16–44) 9 (1.1–16.3) tests, cumulative effects of repeated concussions Volleyball (men) 11 (1.4–21) 9 (0.2–17) have been found to cause deterioration in neu- Source: Junge et al. (2006). ropsychological function among athletes in other 1 Injury rate is reported as the number of injuries per 1000 player sports such as American football and boxing, as matches (with 95% confi dence intervals). well as in non-athletes. 2 Rate of time-loss injuries is reported as the number of injuries expected to lead to time loss from further training and The highest incidence of anterior cruciate ligament competition. (ACL) injuries is seen in 15- to 25-year-old athletes in pivoting sports such as football, basketball and handball. This incidence is three to fi ve times higher expected to cause the player not to continue with among women than men (Griffi n et al., 2006). In subsequent training or match time. Nevertheless, 1970, Kennedy stated that “the anterior cruciate lig- when taking injury severity into account, a research ament is the most common cause of the exathlete.” group within the English Football Association In other words, the treatment offered at the time did found that the overall risk to professional athletes not permit athletes to go back to sport. This is no is unacceptably high—approximately 1000 times longer the case, at least in the short term, thanks to higher among professional football players than the advances in sports medicine research, with major for high-risk industrial occupations (Drawer & improvements in surgical techniques and rehabilita- Fuller, 2002) (Figure 1.1). Although football and tion programs. Today, most elite athletes are initially handball rank highest in injury rates of the team able to resume their sports career, should they wish sports included in the Olympic summer program, to do so. And although the retirement rate may be there are actually other sports where the injury rate higher among athletes with a previous ACL injury is considerably higher, for example, ice hockey and compared with healthy athletes, the main concern the other football codes: American football, rugby, is the dramatically increased risk of long-term seque- and Australian rules football. lae—like abnormal joint dynamics and early onset of Some injury types, such as serious head and degenerative joint disease. Importantly, we still lack knee injuries, are a particular cause of concern. evidence to suggest that reconstructive surgery of Head injuries are known to have a high incidence either menisci or cruciate ligaments decrease the rate among alpine skiers and snowboarders, especially of post-traumatic osteoarthritis (OA). After 10 years, among snowboarders, and the frequency increases approximately half of the patients display signs year by year in this group. Head injury is the most of OA, and it appears that the majority of the frequent reason for hospital admission and most patients will have osteoarthrosis after 15–20 years common cause of death among skiers and snow- (Figure 1.2) (Myklebust & Bahr, 2005). Thus, whereas Why is injury prevention in sports important? 3

1000

Football Football Football Football 100

Unacceptable risk

10 Tolerable risk

Football–OA Acceptable risk 1 Manufacturing

Construction Construction Negligible risk Service Manufacturing 0.1

Service

0.01 Injury risk (injuries per 100,000 h of exposure, log scale) Construction

0.001 Slight Minor Moderate Major Fatality (1–3 days) (4–7 days) (Ͼ4 weeks)

Injury severity (time absent from work/play)

Figure 1.1. Comparison between injury risk (shown on the logarithmic vertical axis as the incidence per 100,000 h of player exposure) and injury risk (shown on the horizontal axis as the duration of absence from work/play, from slight through minor, moderate and major to fatalities) in professional football (Premier League), along with data from the manufacturing, construction and service industries for comparisons. Also, the dark gray areas are classiﬁ ed as unacceptable risk when using industrial standards for risk management. Reproduced with permission from Drawer and Fuller (2002) developing improved treatment methods for injuries, of the literature in December 2007 revealed that in general, and ACL injuries, in particular, remains sports injury prevention research is emerging as an important goal, it may be even more important a new ﬁ eld in medicine. While the number of to prevent injuries. studies on athletic injuries has increased by 43% over the last 7 years, clinical studies and RCTs related to sports injury prevention has increased by Is there an evidence base for injury 200–300% (Table 1.2). Gradually, congresses in sports prevention? medicine, orthopedics, and traumatology include an increasing number of symposia, lectures, and instructional courses on injury prevention issues. The second issue relates to the potential for new Research is also improving in quality, not only in ideas and improved health outcomes. In May quantity. For example, recent issues of high-impact 2000, a PubMed search revealed that out of 10,691 general medical journals such as the British Medical papers on athletic injury, there were only six ran- Journal and the Journal of the American Medical domized controlled trials (RCTs) on sports injury Association have included several papers related to prevention (Table 1.2). However, a similar search injury prevention; two case-control studies among 4 Chapter 1

100 Table 1.2 Results of PubMed searches on sports injury 90 research related to treatment and prevention. 80 Search terms May 2000 December Increase (%) 70 2007 60 Athletic injury 10,691 15,347 43 50 & treatment 6,606 9,774 48 40 & Limit: Clinical 182 359 97 30 trials & Limit: RCT 87 180 107 20 & prevention 2,064 3,319 61

Osteoarthrosis (% of patients) 10 & Limit: Clinical 29 125 330 0 trials 0246810 12 14 & Limit: RCT 21 70 233 Follow-up (years) Note: Results are shown as the number of items resulting from the ACL reconstruction Non-operative search terms shown.

Figure 1.2. Anterior cruciate ligament (ACL) follow- up studies and Osteoarthritis (OA) prevalence. The data illustrate the prevalence of radiographic OA after heart disease, hypertension, colon cancer, obesity, reconstructive surgery with bone-patella-tendon-bone graft and diabetes mellitus in particular. The question is or hamstring graft and after non-operative treatment. The whether the health benefi ts of sports participation dashed line indicates the forced regression (y ϭ 6.0 t; r ϭ 0.85) between time (t) and OA prevalence (y), with the 95% outweigh the risk of injury and long-term disabil- confi dence intervals shown by thin solid lines. Reproduced ity, especially in high-level athletes? A study from with permission from Myklebust and Bahr (2005) Finland has investigated the incidence of chronic disease and life expectancy of former male world- skiers and snowboarders indicating a signifi cant class athletes from Finland in endurance sports, reduction in the risk of head injury with helmet use power sports, and team sports (Sarna et al., 2000). (Hagel et al., 2005; Sulheim et al., 2006), an RCT The overall life expectancy was higher in the demonstrating a 47% reduction in knee and ankle high-level athlete compared to a matched refer- injuries from a structured program of warm-up exer- ence group (75.6 versus 69.9 years). They also cises in adolescent team handball players (Olsen et showed that the rate of hospitalization was lower al., 2005), and an ecological study of a nationwide for endurance sports and power sports compared educational injury prevention program indicating a to the reference group (Kujala et al., 1996). This reduced frequency of spinal cord injuries in rugby resulted from a lower rate of hospital care for heart (Quarrie et al., 2007). Many major public health disease, respiratory disease, and cancer. However, and specialty journals are currently publishing new the athletes were more likely to have been hospi- studies in this fi eld. The publication of these studies talized for musculoskeletal disorders. A follow-up in highly respected medical, physical therapy and study revealed that former team sport athletes had nursing journal illustrates that sports injury preven- a higher risk of knee OA, and other studies have tion is an important public health issue. documented an increased risk of hip and knee arthritis among former football players. Thus, the evidence suggests that although sports participa- Is sports participation healthy? tion is benefi cial, injuries are a signifi cant side effect. To promote physical activity effectively, we have to deal professionally with the health Sports participation is important from a public problems of the active patient. This does not only health perspective. There is no longer any doubt involve providing effective care for the injured that regular physical activity reduces the risk of patient, but also developing and promoting injury premature mortality in general, and of coronary prevention measures actively. Why is injury prevention in sports important? 5

Injury prevention is a complex process. To pre- and injury mechanisms must be ongoing and vent injury, scientists must fi rst correctly identify intervention studies crucial. one or several risk factors, the mechanisms of In an evolving fi eld such as this, international injury, devise an effective intervention to modify cooperation is critical. The involvement of the it, implement the intervention with suffi cient IOC, which highlights sports injury prevention compliance, and study the outcome of the inter- research in this book, improves the dissemination vention with a method that is sensitive enough to of information around the world. In addition, this detect reductions in the injury rate which are clin- book initiative has been supported by all of the ically meaningful. When prevention is successful major sports and sports medicine organizations, or fails, it may not always be clear which step in which bodes well for the future. this chain of events was defi cient. This complexity makes injury prevention diffi cult, but not impossible. A number of interventions have shown a References reduction in injury rates, that is, ACL injuries in team handball and soccer; ankle injuries in soccer, basketball and volleyball; head injuries in hockey Andersen, T.E., Árnason, A., Engebretsen, L., Bahr, R. (2004) Mechanisms of head injuries in elite football. and skiing; wrist injuries in snowboarding; and British Journal of Sports Medicine 38, 690–696. hamstrings injuries in Australian Rules football Bahr, R., van Mechelen, W., Kannus, P. (2002) Prevention and soccer. The list is increasing year by year for of sports injuries. In M. Kjær, M. Krogsgaard, the benefi t of the athlete and the sports. P. Magnusson, L. Engebretsen, H. Roos, T. Takala & S.L.Y. Woo (eds) Textbook of Sports Medicine. Basic Science and Clinical Aspects of Sports Injury and Physical Activity. pp. 299–314. Blackwell Science, Oxford. The future of injury prevention Drawer, S., Fuller, C.W. (2002) Evaluating the level of injury in English professional football using a risk based assessment process. British Journal of Sports Do we need to further develop prevention pro- Medicine 36, 446–451. grams in the future? Year by year we seem to have Griffi n, L.Y., Albohm, M.J., Arendt, E.A., Bahr, R., more information about risk factors and their rela- Beynnon, B.D., Demaio, M., Dick, R.W., tive roles. If the relative additional risk of having Engebretsen, L., Garrett Jr., W.E., Hannafi n, J.A., specifi c risk factors is known, some individuals Hewett, T.E., Huston, L.J., Ireland, M.L., Johnson, R.J., Lephart, S., Mandelbaum, B.R., Mann, B.J., Marks, P.H., should probably be advised against participation Marshall, S.W., Myklebust, G., Noyes, F.R., Powers, C., in certain sports where the risk factor cannot be Shields Jr., C., Shultz, S.J., Silvers, H., Slauterbeck, J., eliminated. On the contrary, if the effect of elimi- Taylor, D.C., Teitz, C.C., Wojtys, E.M., Yu, B. (2006) nating one risk factor after another is known, indi- Understanding and preventing noncontact anterior viduals may be able to participate in sports with cruciate ligament injuries: a review of the Hunt Valley low risk if they are compliant with their specifi c II meeting, January 2005. American Journal of Sports training program. The goal must be to reach a Medicine 34, 1512–1532. Hagel, B.E., Pless, I.B., Goulet, C., Platt, R.W., stage where the risk factors are known and where Robitaille, Y. (2005) Effectiveness of helmets in skiers we can assign a relative risk of an injury to individ- and snowboarders: case-control and case crossover uals. During the preseason examination, individu- study. British Medical Journal 330(7486), 281. als with risk factors can then be assigned training Junge, A., Langevoort, G., Pipe, A., Peytavin, A., Wong, F., programs that have been validated. Even at this Mountjoy, M., Beltrami, G., Terrell, R., Holzgraefe, M., stage, future research in this fi eld is necessary. The Charles, R., Dvorak, J. (2006) Injuries in team sport nature of sports is always changing—becoming tournaments during the 2004 Olympic Games. American Journal of Sports Medicine 34, 565–576. faster and generally more demanding. Just think Kujala, U.M., Sarna, S., Kaprio, J., Koskenvuo, M. (1996) of the difference in alpine skiing over the last Hospital care in later life among world class athletes. 25 years. In almost any sports the same increase Journal of the American Medical Association 276, in pace is seen. Thus, research on risk factors 216–220. 6 Chapter 1

Myklebust, G., Bahr, R. (2005) Return to play guidelines after anterior cruciate ligament surgery. British Journal Further reading of Sports Medicine 39, 127–131. Olsen, O.E., Myklebust, G., Engebretsen, L., Holme, I., Bahr, R. (2003) Preventing sports injuries. In R. Bahr & S. Bahr, R. (2005) Exercises to prevent lower limb Mæhlum (eds) Clinical Guide to Sports Injuries, injuries in youth sports: cluster randomised pp. 41–53. Human Kinetics, Champaign. controlled trial. British Medical Journal Caine, D.J., Caine, C., Lindner, K. (1996) Epidemiology of 330(7489), 449. Sports Injuries. Human Kinetics, Champaign. Quarrie, K.L., Gianotti, S.M., Hopkins, W.G., Caine, D.J., Maffulli, N. (eds) (2005) Epidemiology of Hume, P.A. (2007) Effect of nationwide injury Pediatric Sports Injuries. Individual Sports. Medicine and prevention programme on serious spinal injuries in Sport Science. Vol. 48. Karger, Basel. New Zealand rugby union: ecological study. British Khan, K., Bahr, R. (2006) Principles of sports injury Medical Journal 334(7604), 1150. prevention. In P. Brukner & K. Khan (eds) Clinical Sarna, S., Sahi, T., Koskenvuo, M., Kaprio, J. (2000) Sports Medicine. pp. 78–101. McGraw-Hill, Sydney. Increased life expectancy of world class athletes. Maffulli, N., Caine, D.J. (eds) (2005) Epidemiology of Medicine and Science in Sports and Exercise Pediatric Sports Injuries. Team Sports. Medicine and Sport 25, 37–44. Science. Vol. 49. Karger, Basel. Sulheim, S., Holme, I., Ekeland, A., Bahr, R. (2006) Renström, P.A.F.H. (ed) (1994) Clinical Practice of Sports Helmet use and risk of head injuries in alpine skiers Injury Prevention and Care: Olympic Encyclopaedia of and snowboarders. Journal of the American Medical Sports Medicine. Vol. 5. Blackwell Publishing, Oxford. Association 295, 919–924. Chapter 2 A systematic approach to sports injury prevention Willem Meeuwisse1 and Roald Bahr2

1University of Calgary Sport Medicine Centre, Calgary, Alberta, Canada

2 Department of Sports Medicine, Oslo Sports Trauma Research Center, Norwegian School of Sport Sciences, Ullevål Stadion, Oslo, Norway

Injury prevention in sport has numerous benefi ts. Finally, tertiary prevention is the focus on reha- These include greater health of the individual; bilitation to reduce and/or correct an existing dis- longevity in the activity; and reduced costs to the ability attributed to an underlying disease; what individual, the sport, the health care system, and most people think of as rehabilitation (e.g., in the society. An obvious benefi t is the potential for bet- case of a patient who has had an ankle sprain, this ter performance through injury prevention. This would involve balance board exercises and wearing may be particularly relevant when trying to moti- an ankle brace while gradually returning to sport). vate athletes, coaches, and sports teams to focus on injury prevention. The likelihood of success is greater if all the best players on the team are available for team selection. And the chance of success Sequence of injury prevention research is nil if you are injured when the Olympics start! Prevention can be grouped into three broad In 1992, van Mechelen outlined a sequence of categories of primary, secondary, and tertiary pre- injury prevention research (Figure 2.1). This con- vention. Primary prevention is the goal of most ceptual model can be successfully applied by sports prevention activity, and is what most people think medicine staff, as well. First, according to the of when they consider prevention. That is, primary research model, the magnitude of the problem must prevention involves the avoidance of injury (e.g., be identifi ed and described in terms of the incidence ankle braces being worn by an entire team, even and severity of sports injuries. If you are responsible those with no history of previous ankle sprains). for a team, this would involve monitoring injury If primary prevention activities are successful, an risk on a continuous basis by recording all injuries individual will not sustain injury in the fi rst place. within the squad, as well as training and match This differs from secondary prevention which participation (often called “exposure”). As a second involves appropriate early diagnosis and treat- step in injury prevention research, the risk factors ment once an injury has occurred. The aim here and injury mechanisms must be identifi ed that play is to ensure that the injury is optimally cared for a part in causing sports injuries to occur. For the to limit the development of disability, and is what medical team and coaching staff, this could involve most people think of as treatment (e.g., early RICE systematic steps to examine the athletes and their treatment of an ankle sprain). training and competition program. The third step is to introduce measures that are likely to reduce the future risk and/or severity of injuries. Such meas- Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing ures should be based on information about the risk ISBN: 9781405162449 factors and the injury mechanisms as identifi ed in

7 8 Chapter 2

1. Establishing example, serious knee injuries or head injuries may 2. Establishing etiology the extent of warrant particular attention, not based on injury and mechanisms of the injury sports injuries rate alone, but because they can potentially result in problem: permanent disability and even death. • Incidence • Severity However, when comparing results between studies in different sports and different sports settings, there are a number of important characteristics of surveillance that must be considered, including 3. Introducing a the injury deﬁ nition. There is also the question of 4. Assessing its preventive diagnostic coding or classiﬁ cation of injury and effectiveness by measure repeating step 1 issues surrounding the count of injury and reinjury, and assessment of severity.

Figure 2.1. A model of injury prevention research—the four steps in sports injury prevention (van Mechelen et al., Injury defi nition 1992) Defi ning what constitutes an injury is not as easy as it may seem at fi rst glance, and there have the second step. Finally, the effect of the measures been many different approaches to injury defi ni- must be evaluated by repeating the fi rst step. From tion in the past. A consensus statement was issued a researcher’s standpoint, it is preferable to evalu- in 2006 in the sport of football (soccer) stating ate the effect of preventive measures by means of that the broadest defi nition of injury would be a randomized controlled trial. For the team staff, any event occurring as a result of participation continuous surveillance of the injury pattern within in sport (Fuller et al., 2006). Injury was then fur- the team will reveal whether the changes occur in ther classifi ed into medical attention injuries; those the injury risk (providing the medical staff realize that required assessment or treatment by a medi- that changes in patterns of injury over time in a sin- cal practitioner. A further sub-division was time- gle team can be due to many different factors). loss injuries; those causing a player to miss one or more practices or games or sessions. The important point in any research regarding injury surveillance is that one must know in advance exactly Injury surveillance what will be counted, and this must be consistent across all people and all groups recording injury. The object of surveillance is to enumerate the This is important to ensure consistency both extent of injury in a given group or population. In within a given period of surveillance and over this book, the rate of specifi c injury types across dif- time between different periods of surveillance. ferent sports will be reported. Based on surveillance data from previous studies, we can learn which Injury classifi cation injury types should be targeted when considering Similarly, consensus has been achieved regard- injury prevention in different sports. Surveillance ing the classifi cation of injury into various body within a specifi c team, league, or sport organization regions and injury types (Fuller et al., 2006). These can also highlight potential areas of prevention that can be refi ned more fully within the context of might be unique to that group. A soccer coach may sport through the use of diagnostic coding systems want to focus on hamstring strains, knee and ankle that are tailored specifi cally for sport. sprains, whereas a baseball coach may decide to consider shoulder and elbow problems when planning Injury severity his training and competition program. However, injury rate is not the only factor to be considered. Injury severity can be classifi ed on the basis of the Injury severity is also an important concern. For level of tissue damage, the type of structure injured, A systematic approach to sports injury prevention 9 or the nature of the injury itself. However, within the context of sport the most meaningful meas- Determining the causes of injury ure is likely the amount of time an individual is unable to participate in their customary activity of If one is to prevent injury, the causes of injuries training or competition. Obviously, career-ending must be determined. First, one must identify those injuries or injuries causing permanent disability, factors associated with an increased risk of injury or even death, are a particular concern. The “time (“risk factors”). lost” can be counted in days or sessions (games or practices) missed. The total time lost from injury Risk factors within a team can be used to monitor the quality of not only the effi ciency of the medical team Although all individuals possess certain character- in diagnosing and treating injuries, but also the istics or factors, they are considered risk factors if injury prevention program within the team. they increase the chance of an injury occurring. However, the assessment of risk can be complex, Injury recurrence since most factors in sport do not act in isolation. A risk factor may be part of a collection of other In counting injuries, it is important to realize that factors that, together, produce a picture of “suf- all injuries are not isolated events. That is, some fi cient cause” for an injury to occur. Sometimes, injuries are a recurrence of something that has one specifi c risk factor is necessary and without happened previously, either pre-dating or dur- this factor, an injury will not occur (Meeuwisse, ing the same period of data collection. Fuller 1994; Meeuwisse et al., 2007). et al. (2007) have recommended that recurrence There are many factors that impact on the poten- be grouped into “exacerbations” and “reinju- tial occurrence of injury. There are internal or intrin- ries.” Exacerbations should not be counted as a sic risk factors that are part of an athlete’s make up new injury event, but any time missed should be that may make them predisposed to injury. Then, attributed to the fi rst injury. In contrast, reinjuries they begin to participate and are exposed to external should be counted as a separate injury event with or extrinsic factors, which may make them suscep- their own time loss. If injury surveillance within a tible to injury. These risk factors (often in combi- team reveals an unusually high rate or proportion nation) will determine whether a specifi c event or of recurrences, this could mean that injury reha- force will produce an injury (Figure 2.2). bilitation is insuffi cient or that athletes are allowed In some cases the risk factor that is being evalu- too early return to play after previous injuries. ated is not the cause of injury. Interestingly, if the factor is shown to be associated with an increased Exposure risk of injury it is considered a risk factor. This allows this factor to be a valid predictor or marker With injury surveillance one can look at numbers of injury. However, removing the risk factor may of new injuries over a period of time. However, not necessarily prevent injury if a causal relation- within the context of sport where there is varying ship does not exist. degrees of participation (and therefore exposure to the potential of injury), it is more meaningful to Etiology capture injuries in reference to the amount of time that a given individual participates. Participation In some instances the immediate cause (or eti- can be counted in hours or sessions. From this, an ology) of injury is obvious. However, all is not injury rate, or incidence rate, can be calculated. In always what it appears to be. Even in the most this book injury incidence is typically reported as obvious examples, there is often more than one the number of injuries per 1000 hours of player factor that has led to the injury. In the case of a exposure. This allows injury risk to be compared macro-traumatic injury, such as a kick to another between different sports and different groups. player’s leg resulting in a muscle contusion, there 10 Chapter 2

Risk factors for injury Injury mechanisms (distant from outcome) (proximal to outcome)

Intrinsic risk factors:

• Age • Gender Predisposed Susceptible • Body composition (e.g., INJURY athlete athlete body weight, fat mass, BMD, anthropometry) • Health (e.g., history of previous injury, joint instability) Exposure to extrinsic Inciting event: • Physical fitness (e.g., risk factors: muscle strength/power, • Playing situation maximal O2 uptake, joint • Human factors (e.g., team • Player/opponent ROM) mates, opponents, referee) “behavior” • Anatomy (e.g., alignment, • Protective equipment (e.g., • Biomechanical intercondylar notch helmet, shin guards) characteristics width) • Sports equipment (e.g., skis) • Skill level (e.g., sport- • Environment (e.g., weather, specific technique, snow and ice conditions, floor postural stability) and turf type, maintenance)

Figure 2.2. A model of injury causation (Meeuwisse, 1994; Bahr & Krosshaug, 2005)

may have been factors related to the injured An athlete then begins to participate in sport player, the opponent, the equipment, the play- within a certain environment and is exposed to ing environment, etc., which all could have con- extrinsic risk factors. These may include equipment tributed to the injury occurring, or its severity. and fi eld conditions, for example, fl oor friction in Therefore, it is important to take a more encom- indoor team sports, snow conditions in alpine skiing, passing view of etiology or causation. a slippery surface (running track), very cold weather, A model has been developed in the past to or inappropriate footwear. Extrinsic factors may also account for a number of different variables that may reduce injury risk, such as the wearing of protec- contribute to injury. Meeuwisse (1994) outlined a tive equipment. Exposure to such external risk fac- model wherein an athlete begins with a certain set tors may interact with the intrinsic factors to make of characteristics (Figure 2.2). These are typically the athlete more or less susceptible to injury. When referred to as intrinsic risk factors or internal fac- intrinsic and extrinsic risk factors act simultaneously, tors which may predispose the athlete for injury. the athlete may be at far greater risk of injury than This includes athlete characteristics: factors such when risk factors are present in isolation. as age, maturation, gender, body composition, and The fi nal link in the chain is the inciting fi tness level. One factor that consistently has been event, which is usually referred to as the injury documented to be a signifi cant predictor is previous mechanism—what we see when watching an injury—almost regardless of the injury type studied. injury situation. Each injury type and each sport Intrinsic factors such as these interact to predispose does have its typical patterns, and for team medi- for injury, or in other cases protect from injury. cal and coaching staff it is important to understand Examples of factors which may make an athlete the typical injuries and mechanisms in their sport less predisposed to some, but not all, injury types (Bahr & Krosshaug, 2005). include fi tness-related factors such as muscle mass, It has been recognized more recently that this strength, balance, and neuromuscular control. process should not be seen as linear and static. A systematic approach to sports injury prevention 11

That is, it does not have a clear starting and is not just because of external changes such as dif- ending point in the context of sport. Athletes par- ferences in weather or playing surfaces or equip- ticipate in sport over typically a long period of ment worn. Internal risk factors can also change time and bring with them characteristics of prior as a result of participation. Specifi cally, an ath- training as well as other sport experience and lete’s susceptibility to tissue-level damage may be injury. Moreover, they carry their intrinsic risk fac- reduced as strength improves with repeated use or tors with them into repeated exposure to extrinsic as technique becomes adapted in a positive man- risk factors and many potentially inciting events, ner. At the same time, repeat participation can most of which never result in injury. produce microtrauma that weakens tissue and Therefore, one limitation of the model is that it is increases susceptibility to injury. In addition, ath- not obvious how the athlete’s training routine and letes may change their behavior, their style of play competitive schedule can be taken into considera- or even their choice of protective equipment based tion as potential causes, and the model has there- on a perceived susceptibility or risk of injury. These fore traditionally mainly been used to describe the circumstances do not tend to remain constant causes of acute injuries. For overuse injuries, the even within one player over the course of time. causative factors can sometimes be distant from Rather, adaptations or changes may occur during the outcome. For example, for a stress fracture in a a season through both training and competition. long distance runner the inciting event is not usu- The behavior of these factors have been described ally the single training session when pain became in more detail by Meeuwisse et al. (2007). evident, but the training and competition program he or she has followed over the previous weeks or Modifi able and non-modifi able risk months. factors Another limitation is that repeated exposure may produce adaptation, either in the course of normal Assuming that a risk factor is a cause of injury, the training or as a consequence of being exposed to best way to prevent injury is to change the risk potentially injurious events. Overuse or gradual factor. For example, a risk factor of muscle weak- onset injuries are typically produced as a result of ness can be overcome with a strengthening pro- high training loads over a period of time. In some gram, or a risk factor of poor proprioception can athletes, these training loads will result in adapta- be improved by balance re-training. In addition, if tion and the athlete will actually become stronger artifi cial turf were a risk factor, it could be mini- and therefore have an improved (reduced) set of mized by playing on grass. intrinsic risk factors. In other athletes, this may However, in some cases, the risk factor cannot be result in tissue breakdown and microtraumatic changed, eliminated, or modifi ed. Even so, non- changes that would worsen (increase) their intrin- modifi able factors (such as gender) may be equally sic risk factors. important in injury prevention if they can be used Ultimately, this happens on a cyclical basis for to target intervention measures to those athletes every single participation in sport (Meeuwisse who are at increased risk. For example, anterior cru- et al., 2007). As athletes are exposed to the play- ciate ligament (ACL) injuries have been shown to ing environment and face different events, some of be four to six times more common among female those will become an inciting event and therefore athletes than male athletes in some sports, such a mechanism for injury. Others, however, produce as soccer, basketball, and handball. Based on this, no injury but rather adaptations in the athlete, female athletes should be the primary target group which may be biomechanical, structural, behavio- for ACL injury prevention programs in these sports. ral, etc. Then, these athletes repeatedly participate in sport, creating a dynamic cycle wherein repeat The mechanism of injury participation can result in either injury or no injury. Therefore, it is important to keep in mind that In some cases, the key to injury prevention may risks will change under repeated participation. This lie with the injury mechanisms, not with the risk 12 Chapter 2 factors. For example, one may consider being struck in the face by a hockey puck or stick as a completely random event, which could occur regardless of intrinsic or extrinsic risk factors. If defenders and attackers are hit as often as goalies, it may not be possible to identify the player at risk. And even if the chance of being struck were twice as high for goalkeepers, a face mask would be the obvious preventive measure and the key question would be how to design such a mask, and not who should wear it. To fully understand the inciting event, and the ultimate chain in the factors leading to injury, it is helpful to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player, and opponent behavior), as well as includes a description of whole body and joint biomechanics at the time of injury (Bahr & Krosshaug, 2005). Ideas for preventive measures may originate from each category of information, depending on the injury type in question. For some injury types, the key to prevention may lie with the events leading to the injury situ- Figure 2.3. Typical mechanism for head injuries in soccer. Elbow to head contact in a heading duel. The player ation (e.g., the playing situation, player behavior, on the left uses his right elbow actively above shoulder or opponent behavior). For example, to prevent level to prevent the opponent player from reaching the head injuries in soccer the fi rst obvious question ball. Reproduced from Bahr and Krosshaug (2005) with is: What strikes the head? The ball? Or is it a head- permission to-head clash with an opponent in a heading duel? Or the opponent’s arm or elbow? Or do head injuries typically result when falling and hitting the and describe the injury mechanisms are shown in ground? Recent studies from elite male soccer on Table 2.1. Such information can be obtained from the national and international level have shown a variety of research methods, each with its own that the commonest mechanism involved head- strengths and limitations. These include interviews ing challenges and the use of the upper extrem- of injured athletes, analysis of video recordings of ity with elbow to head contact. In the majority of actual injuries, clinical studies (where the clinical the elbow to head incidents, the elbow was used joint damage fi ndings are studied to understand actively at or above shoulder level (Figure 2.3). the injury mechanism through examination, diag- From these fi ndings stricter rule enforcement and nostic imaging, or surgical exploration), in vivo even changes in the laws of the game concerning studies (measuring ligament strain or forces to elbow use can be made to reduce the risk of head understand ligament loading patterns), cadaver injury. studies, mathematical modeling and simulation In other sports, it may be more important to of injury situations, or measurements/estimation have detailed knowledge of the biomechanics. from “close to injury” situations. For most injury For example, to design an appropriate hockey hel- types, one research approach alone will not be met, it is necessary to have an accurate estimate suffi cient to describe all aspects of the injury situ- of the impact forces involved in the game, such as ation. A broader and more precise understand- when a falling player hits the ice. Other examples ing could be attained by combining such research of factors which may be important to understand approaches as athlete interviews, video analysis, Table 2.1 Categories of injury mechanism descriptions with examples of elements and descriptions.

Category Elements Examples of factors describing the injury mechanism

Non-contact ACL injury in ACL injury in a mogul Knockout in boxing Lower leg stress fracture in basketball skiing jump landing football

Playing (sports) Team action Fast break Course steepness Uppercut, Hook Exposure to matches and training (total load) situation

Skill performed prior to, Zone defense Jump elements (e.g., Counterattack Midfi elder with defensive and offensive tasks and at, the point of twist, helicopter) (i.e., many runs in matches/training) injury Court position Charging Jump height and length Foot work Hard working team Player position Cutting Forced into the corner/to Frequency of duels the ropes Ball handling Setting up for a shot Ring-side referee decision Defensive rebound Inter-boxer distance Man-to-man defense Athlete/opponent Player performance Effort Rhythm and balance Awareness Effort behavior prior to the jump Opponent interaction Perturbation by opponent Concentration Aggressiveness Toe/heel runner Player attention Intention Balance Punching power Jumping technique Foot fi rmly fi xed to the fl oor Boot-binding release Punching speed Duel technique Intention Visual control Balance Technical foul Jumping technique Over-rotation Falling technique Whole body Description of whole Sideways translation Linear and angular Center of mass velocity Stride length biomechanics body kinematics and momentum kinetics Rotation of the body Energy absorption Punching force Stride frequency around the fi xed foot Speed at impact Center of mass to the Punching direction Vertical excursion rear Foot in front of center of Weight distribution on Ground reaction forces mass the legs Knee fl exion angle Joint/tissue Detailed description of Valgus moment Shear forces Energy transfer Bending moment biomechanics joint/tissue kinematics and kinetics Pivot shift of the tibia Anterior drawer Head acceleration Shear forces relative to the femur Notch impingement Intercondylar lift-off Pressure distribution and Surface/shoe dynamics localization Loading rate

Reproduced from Bahr and Krosshaug (2005) with permission. ACL ϭ anterior cruciate ligament. 14 Chapter 2 and clinical studies, or by combining video analy- accidents, it represents a useful approach for ana- sis and studies using cadavers, dummies, or math- lyzing potential injury prevention methods when ematical simulations. The multifactorial nature applied to sports. of sport injuries is important to consider in these studies to understand why certain forces lead to Pre-crash measures injury in some cases, but not in others. Examples will be presented in the subsequent chapters deal- Measures related to the pre-crash stage have been ing with specifi c injury types. developed to counteract potential injury-causing situations by preventing accidents altogether. In sports, examples of athlete-related pre-crash meas- Developing intervention methods and ures include ensuring adequate, sport specifi c, programs physical conditioning of athletes, increasing their skill level, and improving neuromuscular control and agility to avoid situations where they The third stage in van Mechelen’s approach is the might get injured. Psychosocial variables may be introduction of prevention measures. The devel- addressed in an effort to infl uence the athletes’ opment of injury intervention programs depends resiliency and injury vulnerability. In addition, to a large extent on the previous step wherein sport-specifi c screens may help identify athletes at causes of injuries are identifi ed. Strategies for risk for injury and modify their risk prior to partic- injury control have been developed from other ipation. Examples of environmental pre-crash meas- research areas, particularly from research on motor ures include modifying the friction of the playing vehicle accidents. One such model, the injury pre- surface (too high may lead to twisting injuries to vention matrix, has two dimensions (Table 2.2). the lower extremity, too low may lead to slipping One dimension relates to whether the measure and falling injuries) or changing regulations to is designed to avoid accidents altogether (pre- avoid dangerous plays. Equipment-related pre-crash crash measures), to avoid injury even if an acci- measures include modifying shoe friction and dent occurs (crash measures), or whether it aims choosing cleat length according to the playing sur- to minimize the consequences of an injury (post- face and weather conditions. All of these measures crash measures). The other dimension relates to are based on modifying risk factors that have been whether the measure targets the individual, the shown to be a cause (or part of a cause) of injury. environment, or perhaps equipment used. Other categories are also possible along this dimension. Crash measures Although Haddon (1980) originally developed the injury prevention matrix for motor vehicle Measures related to the second stage, the crash stage, have been developed to protect the athlete

Table 2.2 Haddon’s matrix applied to sport injury against injuries if a potentially harmful situation prevention: Measures introduced to prevent sport arises. These measures mainly focus on assisting injuries. athletes to withstand the forces involved when a collision or a fall occurs. Athlete-related crash Pre-crash Crash Post-crash measures could involve, for example, a general Athlete Technique, Training status, Rehabilitation strength-training program, fl exibility program, Neuromuscular Falling techniques or falling techniques. Environmental crash meas- function Surroundings Floor friction, Safety nets Emergency ures include safety nets to avoid falling alpine Playing rules medical skiers from fl ying into the crowd or soft mats coverage protect gymnasts failing to dismount or falling Equipment Shoe friction Tape or brace, First-aid down from an apparatus. There are many exam- Ski bindings, Leg equipment, ples of equipment-related crash measures in sports, padding Ambulance such as release bindings for alpine skiing, helmets A systematic approach to sports injury prevention 15 and pads for various sports, taping and braces for leagues where the type of facial protection in ice joints, shin guards, and eye protection. hockey is optional, players at the varsity/college level have been shown to choose the minimum Post-crash measures level mandated. There is an inherent level of risk that athletes appear to be willing to absorb, which Post-crash measures are designed to minimize the may be a barrier to adopting active measures. damage resulting from an injury and the risk of reinjury (which is a strong risk factor for sports injuries), and mainly relates to the chain of medi- Implementing injury prevention cal treatment provided after an injury. Post-crash programs measures in sports may include providing adequate medical services during sports events (personnel and equipment); training athletes and coaches to Once methods with a potential for prevention provide adequate on-fi eld fi rst aid, including quick have been identifi ed, there is a need to carefully evacuation procedures to a hospital in the case of develop the prevention measures, assess them severe injuries, adequate rehabilitation programs under ideal conditions, and consider the imple- for injured athletes and ensuring appropriate medi- mentation context (Finch, 2006). cal clearance before they return to competition. An important part of the development of interventions is fi rst testing their effi cacy. This means Active versus passive measures that under ideal conditions, they are tested to determine if the intervention works. This is typi- Injury prevention measures can also be categorized cally done in a controlled research setting with as active or passive (Haddon, 1974). Examples extensive monitoring and measurement of com- from motor vehicle accident prevention are seat pliance with the intervention. This differs from belts (active) which require the individual to fasten effectiveness, which is where an intervention is them, and air bags (passive) which do not require implemented in a broader context, often in a com- the operator to take any action. In between these munity or sport setting, where the degree of atten- extremes there are measures which require some tion to the program and monitoring is much less. action by individuals. An example is where specifi c If we use the analogy of a drug, effi cacy would safety gear is required in the rules of the sport; that be the question of whether the drug works under is, this requires some action by the individual, but controlled conditions of ideal use. Effectiveness this action is a prerequisite to be allowed to partici- would measure whether the drug worked in a pate. This is the case for helmet wear in ice hockey given patient, who may be affected by side effects, and competitive skiing and snowboarding. In con- convenience of use, etc. Therefore, the culture of trast, among recreational skiers and snowboard- sport has a major infl uence on the effectiveness of ers, helmets are still not required by most skiing intervention programs. Specifi cally, attitudes and resorts. In this setting, helmet use must be consid- behaviors or historical biases within the sport may ered an active measure, dependent on education prove to be either incentives or barriers to effective and attitudes with signifi cant barriers in terms of implementation of injury prevention programs. cost and availability. To build on our earlier example, the move to man- The distinctions are not merely classifi cations. date full facial protection in adolescent ice hockey They have direct, practical relevance. Historically, was initially resisted due to concerns from sport passive approaches, when available, have a spec- administrators that the nature of the game would tacularly more successful record in injury preven- be altered, and from medical personnel that such tion outside of sport. This is also the case within changes could lead to an increase in neck injuries. the sports context, where there is a long tradi- Therefore, the development of injury prevention for mandating safety equipment, and specifi c tion programs must take into consideration more safety standards for sports venues. For example, in than the biomechanics of injury or their specifi c 16 Chapter 2 immediate causes. It must also engage stakehold- Haddon, Jr., W. (1980) Advances in the epidemiology of ers within the sport and/or community to under- injuries as a basis for public policy. Public Health Report 95, 411–421. stand some of the behavioral aspects and norms of Meeuwisse, W. (1994) Assessing causation in sport injury: the environment in which sport and injury occur. a multifactorial model. Clinical Journal of Sport Medicine If a prevention program is biologically appropri- 4(3), 166–170. ate, but not appropriate within the context of Meeuwisse, W., Tyreman, H., Hagel, B., Emery, C., (2007) the sport, it has little hope of being adopted and A dynamic model of etiology in sport injury: the therefore little chance of being effective. recursive nature of risk and causation. Clinical Journal of Sport Medicine 17(3), 215–219. van Mechelen, W., Hlobil, H., Kemper, H. (1992) Incidence, severity, etiology and prevention of sports injuries—a References review of concepts. Sports Medicine 14(2), 82–99.

Bahr, R., Krosshaug, T. (2005) Understanding injury mechanisms: a key component of preventing injuries Further reading in sport. British Journal of Sports Medicine 39, 324–329. Finch, C. (2006) A new framework for research leading to sports injury prevention. Journal of Science and Medicine Andersen, T.E., Árnason, Á., Engebretsen, L., Bahr, R. in Sport 9, 3–9. (2004) Mechanisms of head injuries in elite football. Fuller, C., Ekstrand, J., Junge, A., Andersen, T.E., Bahr, R., British Journal of Sports Medicine 38, 690–696. Dvorak, J., Hägglund, M., McCrory, P., Meeuwisse, W. Bahr, R. (2003) Preventing sports injuries. In R. Bahr & (2006) Consensus statement on injury deﬁ nitions S. Mæhlum (eds) Clinical Guide to Sports Injuries, and data collection procedures in studies of football pp. 41–53. Human Kinetics, Champaign. (soccer) injuries. Clinical Journal of Sport Medicine 16(2), Khan, K., Bahr, R. (2006) Principles of sports injury 97–106. prevention. In P. Brukner & K. Khan (eds) Clinical Fuller, C., Bahr, R., Dick, R., Meeuwisse, W. (2007) Sports Medicine, pp. 78–101. McGraw-Hill, Sydney. A framework for recording recurrences, re-injuries and Meeuwisse, W., Wiley, J. (2007) The sport medicine exacerbations in injury surveillance. Clinical Journal of diagnostic coding system. Clinical Journal of Sport Sport Medicine 17(3), 197–200. Medicine 17(3), 205–207. Haddon Jr., W. (1974) Strategy in preventive medicine: Rae, K., Orchard, J. (2007) The orchard sports injury passive vs. active approaches to reducing human classiﬁ cation system (OSICS) version 10. Clinical wastage. The Journal of Trauma 14, 353–354. Journal of Sport Medicine 17(3), 201–204. Chapter 3 Developing and managing an injury prevention program within the team Andrew McIntosh1 and Roald Bahr2

1School of Risk and Safety Sciences, The University of New South Wales, Sydney, Australia 2Department of Sports Medicine, Oslo Sports Trauma Research Center, Norwegian School of Sport Sciences, Ullevål Stadion, Oslo, Norway

We are all aware how important it is to manage of identifying, assessing, and controlling risks. risks. Most of us have insurance in case something It can be applied within and across sport in the goes wrong. Many people who play sport will upper levels of policy and administration, in a have health insurance or sports injury insurance team, and by an individual. through their club or association. This is certainly Injury risks have been identifi ed in most sports. important and will assist in managing the conse- This process is often general, for example, partici- quences of injury, but does not contribute greatly pants in contact sports experience head injuries. to injury prevention on an individual or team Risk assessment is a more formal process of meas- basis. This chapter will describe the components, urement and/or estimation of hazards and risks to activities, and strategies required to develop and athletes on a team. This means measuring the inci- manage injury risks in a team setting. The “team dence and severity of injuries, associated injury setting” not only denotes the team of players that risk factors, and injury mechanisms, as described run out onto the fi eld. It also includes teams of in Chapter 2. Risk evaluation involves determin- athletes in individual sports, such as a swimming ing the signifi cance and acceptability of the risks team or an alpine skiing team, and includes the to all stakeholders; including the athletes, the support team—manager, coach, trainer, physi- coaches, and the club. otherapist, and doctor. Communication and coor- Risk control is the process of identifying and dination within the support team and between it implementing methods to control the level of expo- and the athletes is a requisite feature of risk man- sure to hazards and/or the consequences. There are agement in sport. four options for risk control: eliminate, retain and manage, outsource, and insure. All options could be in play, each addressing a range of risks. In sport, Principles of risk management controls are largely restricted to retain and manage, and insure. There is the presumption that the team The principles of risk management applied to the has decided to participate in the sport, so elimination sports setting have been described in detail by Fuller of the sporting activity is not an option, although (2007). Risk management is the overall process under some circumstances a team may decide not to participate in a specifi c event. For example, in recent years there has been discussion about teams touring Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing in countries where there has been recent political ISBN: 9781405162449 unrest, war, or terrorism. Teams might agree to cancel

17 18 Chapter 3 a round due to adverse weather, thereby eliminating the injury risks in the sport and bring these to the all sports injury risks on that day. From a team’s per- attention of the team in its various shapes and spective, it might be possible to outsource medical sizes. In many sports there is already a strong rec- services and management of venues. A sports team ognition of injury risks. Simply having good on- could not be outsourced, whereas a cleaning func- and off-fi eld medical treatment and rehabilitation tion in a company could be outsourced to contrac- is not injury risk management. tors. The two choices that are most often faced are The basic steps that will identify injury risks either to accept a risk or reduce a risk. Risk accept- include: ance implies that an informed decision has been • reviewing injury reports from at least one made to accept the consequences and/or likelihood season; of an injury. These risks may be mitigated through • reviewing player turnover and availability insurance, to cover any losses. This approach does within one or more seasons; allow all stakeholders to continue their program • reviewing the literature on injury risks in the unchanged in the knowledge that their insurance specifi c sport. will cover their loss in case of injury, but does not The person or group who identifi es the risks provide much incentive for injury prevention pro- may then need to be advocates within the team or grams. In professional sports many clubs approach club for risk assessment and control. This will ide- the injury issue simply by employing extra players ally form the basis of a risk management program for each position when injuries occur, which repre- that is adopted and managed by the club or team. sents another form of risk acceptance. As mentioned earlier, risk assessment is the for- Although participants may appear to accept the mal process of measuring hazards and risks and level of risk associated with a sport, this is often reviewing these. It may be necessary to undertake the result of ignorance of the actual levels of risk prospective studies of injury rates, patterns, and involved. This is clearly an important issue, because potential risk factors within a team. Some of the it is diffi cult for a participant to accept risks about major sports have developed guidelines for injury which they have no knowledge. In most cases, surveillance. Several leagues, such as the National acceptable levels of risk in sport are determined Hockey League, have established systems where more by the risk perceptions of the participants every patient’s record recorded by the medical than by actual data on the risks involved. Another team is linked to a central database. In this way the diffi culty lies in the fact that, in contrast to other league can monitor injury trends and every team occupations, there are no accepted standards to can assess their own injury rates and compare them- which risks can be compared. selves to the league average. Other examples are Risk reduction, on the other hand, involves devel- the International Skiing Federation (FIS), which has oping and applying methods to prevent injuries established an injury surveillance system to record and/or reduce their consequences. In addition to all injuries during their World Cup; the FIS Injury the obvious benefi ts to the individual athlete, there Surveillance System (FIS ISS); and the National is also a fi nancial incentive for sports teams through Collegiate Athletic Association (NCAA), which reduced insurance costs and less need to employ developed its injury surveillance system in 1982 to extra players. In recreational and youth sports, risk provide current and reliable data on injury trends reduction approaches may assist in maintaining or in US intercollegiate athletics. Injury and exposure developing the sport’s viability through retaining fi t data are collected yearly from a representative sam- participants and promoting the sport as being safe. ple of NCAA member institutions and the resulting data summaries are reviewed by the NCAA Sport Risk identifi cation and assessment Rules Committees and by the NCAA Committee on Competitive Safeguards and Medical Aspects of The establishment of a risk management program Sports. The web-based system also allows individual in a team setting might be driven from the top or schools to have a real-time electronic injury record from the grass roots. The fi rst task is to identify of their specifi c injuries. The goal of both of these Developing and managing an injury prevention program within the team 19

Catastrophic SCI

Major Punctured Femur fractures Shoulder lung Ankle dislocation syndesmosis Knee injuries ligament injury

Moderate Fractured Thigh strains forearm, Concussion, Fractured

Consequence collar bone Minor Fractured hand/finger

Insignificant Cuts and Abrasions,

Rare Unlikely Moderate Likely Almost certain Likelihood

Figure 3.1. Qualitative risk matrix in community rugby; relationship between injury severity (consequence) and injury frequency (likelihood)

surveillance systems is to reduce injury rates is a continuous development of new methods. The through suggested changes in rules, protective diffi culty faced by many is gaining access to this equipment, or coaching techniques based on data information and staying abreast of the develop- provided. ments; it is time consuming and often highly tech- A key element is that injury surveillance is a nical. Often the existence of effective controls, for continuing process. Not only are there seasonal example, breakaway bases in softball and baseball, changes, but injury data may assist in identifying take many years to be recognized and adopted. the level of success of injury prevention strategies. The “hierarchy of controls” (Figure 3.1) should A formal survey, perhaps using a questionnaire be followed, but it is recognized that in sport, engi- or interview, of the player cohort might also be neering controls might be diffi cult to apply. The helpful in assessing risks and provide results with- hierarchy is in the descending order of effective- out the need to wait for one year. As discussed in ness: elimination, substitution, engineering con- Chapter 2, there may also be a number of risk fac- trols, administrative controls, training, and personal tors, internal and external, that should be assessed protective equipment. The following are examples (Figure 2.2). of each of these controls in skiing. Once there is a decision to participate in a spe- Risk control: injury prevention cifi c sport, it may be very diffi cult to eliminate all hazards and risks. Let’s consider a pole on a ski Once there is a clear understanding of hazards run that serves the function of supporting a video and risks, and preferably a quantifi able level of camera that provides an important view of the risk, decisions are required about interventions to skier. A pole is a collision hazard in a high kinetic control those risks. Many controls exist and there energy sport. The pole could be eliminated and no 20 Sports Injury Prevention

injury prevention methods (related to host, agent, physical environment, and social environment) are categorized based on their ability to prevent Elimination accidents altogether (pre-crash), to prevent injury even when there is an accident (crash), or prevent Substitution disability even when there is an injury (post-crash) Engineering controls (Table 2.2). This approach has been described in more detail in Chapter 2. Clearly training of the support staff’s response to a serious injury will Administrative controls assist post injury, as will provision of vehicle access to the ground (post-crash). Whereas, team Training skill training will hopefully prevent unintentional impacts between players within a team (precrash). Personal protective equipment Improving personal protective equipment function will assist in preventing the injury (decreasing the Figure 3.2. Hierarchy of controls risk) during the event (crash). Administrative controls that mandate PPE and education are preevent interventions. video recorded. The pole could be eliminated and a camera far removed from the ski run installed Reaching agreement with lenses to substitute for the proximity. The pole could be substituted by a crane or wires that Agreement on injury prevention within the team, suspend the camera at the site. An engineering solu- between teams and within a competition is impor- tion might be to manufacture a frangible pole that tant. Agreed objectives for the season might be breaks away during a collision at a force lower than a 30% reduction in lost time injuries or 100% that which would cause injury. Administrative pro- compliance with equipment use protocols, or cedures could be implemented to determine where return to play guidelines. Objectives need to be poles could be placed and a process for inspecting realistic, important, and common from the play- the ski run adopted. The skier could be offered per- ers to the offi cials. sonal protective equipment, for example, a helmet The following discussion will focus on two areas. and a padded suit, to protect the skier if collision First, it will discuss the various steps and activi- occurs. An additional administrative control would ties which may form part of a risk management be to mandate the use of that equipment. Finally, program, focusing on the potential roles of medi- the skier could be trained not to collide with poles cal staff. Second, it will discuss the importance of while skiing competitively. However, we know that equipment and facilities in injury prevention. even the most skillful athletes err. Sport has often restricted itself to the less effective controls—personal protective equipment, train- The roles of the medical staff ing individual and team skills plus fi tness, and rules. It may also be diffi cult to implement controls on a team basis because rules of the game, including those Although not all teams have medical staff as part that govern protective equipment use and infrastruc- of the support structure, this section will discuss ture, are determined at a national or international the potential involvement of team medical staff level. Disagreements might arise within a compe- (physicians, physiotherapists, athletic trainers, tition if, for example, a team decided to prepare its etc.) in the development of a risk management home ground to be slow in order to reduce injury. program. These include: Another way of looking at hazards, risks, and con- • recording of injury and participation data to trols is through the injury prevention matrix, where develop an injury surveillance program; Developing and managing an injury prevention program within the team 21

• season analysis—review of training and compe- Another task is to establish a system to record tition program; individual training and competition exposure • preseason screening of physical and behavioral within the team. This represents a challenge capabilities, limitations, and injury; for the medical team, since they are not always • monitoring “at risk” team members, for exam- present during practices or on road trips, and ple fi tness, technique, and behavior; therefore this task is often done by the coaching • education regarding injury management and staff. Many of the injury recording software pro- prevention; grams also have the capability of recording expo- • coordination of injury risk management; sure data, which can then be entered based on the • identifi cation of emergency management coaching records. Exposure data is necessary to requirements; calculate risk as described in Chapter 2, and the • synthesis of “best practice” and emerging trends standard method for calculating injury incidence from professional and scientifi c literature. rates is the number of injuries per 1000 hours Access to team physicians, physical therapists, of exposure, which is typically used in football athletic trainers, and other health professionals is codes. For some sports and specifi c player posi- mainly available at the elite and professional lev- tions, for example, a pitcher or a bowler, injuries els of sport. Nevertheless, many of the risk man- per balls delivered may be a more powerful meas- agement functions listed earlier can be performed ure from the perspective of identifying relation- by coaching staff, parents, or the athlete. ships between injury and exposure. It may also be Note that there are privacy issues related to relevant to record exposure in relation to exter- management of individual injury/medical infor- nal risk factors, such as turf type (e.g. training on mation. There is a need for strong trusting rela- grass, gravel, artifi cial turf), use of personal protec- tionships within the team. Guidelines are available tive equipment, and whether the exposure is dur- which defi ne appropriate lines of communication ing competition or training. so that medical staff can maintain a confi dential Interpretation of injury data is diffi cult unless relationship with a player, but still provide perti- exposure data are collected. Consider the exam- nent information to team management (Anon., ple where there is an increase in the number of 2000). match injuries from one season to the next. If the number of matches increases by 30%, there would Developing an injury surveillance be no increase in injury incidence. program within the team If no medical team is available, it is still possible to develop useable systems to record valuable Risk management is based on continuous risk injury information. In its simplest form, the coach assessment. To assess risk within a team, it is or assistant coach could keep attendance records necessary to establish a system to monitor inju- and simply note absences due to injury through- ries and exposure. For medical staff, recording out the season (and the injury type in question). injuries should represent one of the easiest tasks At the end of the season, the coaching staff would in risk management; they are required to keep then be able to calculate the number of injuries accurate records of all assessments and treat- and the number of days of absence attributable to ment provided to their patients. Thus, establish- injury, as well as the main descriptors of injury. ing a surveillance system only involves analyzing As described in Chapter 2, injury risk is not just information that is already there. To make this a question of injury incidence. The severity of task even easier, excellent electronic tools are injury must also be taken into account, and most available, where the necessary statistical tools often severity is expressed as the number of days have been integrated in software which helps to of absence from sports because of an injury. Based maintain patient’s records. Nevertheless, even at on this, the total injury risk to a team can be cal- the highest levels of sport, this is rarely done on culated as the product of injury incidence and a routine basis. injury severity. This is shown in Table 3.1, using 22 Chapter 3

Table 3.1 Variations in the observed values of incidence, severity, and risk for injuries sustained in rugby union matches. Reproduced with permission from Fuller (2007).

Injury type Incidence Severity Risk (injuries/1000 player hours) (days/injury) (days/1000 player hours)

Cervical facet joint injury 2.00 10 20 Foot fracture 0.42 44 18 Foot stress fracture 0.12 151 18 Thigh hematoma 8.00 6 48 Lateral ankle ligament injury 4.20 12 50 Wrist/hand fracture 1.10 43 47 Medial knee ligament injury 3.10 31 96 Shoulder dislocation/instability 1.30 81 105 Anterior cruciate ligament injury 0.42 258 108

a range of injuries sustained by players during This information may be used to improve coach- rugby union matches as an example. This example ing and individual player skills. At the community shows that in terms of risk, thigh hematomas rep- level these expensive resources are absent. resent much less of a concern than anterior cruci- When assessing data from injury surveillance, ate ligament injuries do, even if they are 16 times it is important to recognize that within a team, more common! it is very unlikely that a suffi ciently large sample Injury data can also be illustrated by a risk matrix size exists through which the benefi t of a sin- that highlights risks in terms of likelihood and gle or multiple interventions can be assessed. consequences. This is an appropriate and powerful Therefore, “success” or “failure” in few individuals tool for presenting injury risk data. The example should not be considered justifi cation for a com- shown in Figure 3.2 is derived from rugby union. plete overhaul of the team’s training and injury It suggests that injury reductions in the areas of prevention programs. In the same way, seasonal shoulder dislocation and knee ligament injury are variation in sports injury may simply be due to priorities, as it is in spinal cord injury prevention. chance. Often the media report a number of simi- By examining factors that contribute to the cau- lar catastrophic sports injuries over a period of a sation of shoulder and knee injuries, strategies to few weeks which gives the impression that a prob- reduce injury rates can be formulated. lem is out of control. There is no need to panic or At the highest levels of play, teams may even overreact, especially if there has been continuing want to monitor injury mechanisms using match injury surveillance. tapes. In professional sports, fi rst-class video recordings are available from all matches and Season analysis: review of training and sophisticated software has been developed to ana- competition program lyze play-by-play performance of players. This represents an opportunity to index and analyze One helpful method to manage risk in sports is all injury situations, as well. Such analyses may a formal review of the training and competition reveal whether there are certain situations with a program to identify risks prior to the start of the high propensity for injury, or improper technique season. The method of season analysis therefore or inadequate tactical responses on the part of the is fundamentally different from injury surveil- injured athlete. Even if more sophisticated analy- lance, where data on injuries are collected as they sis of the inciting event is laborious, and perhaps happen. Season analysis represents an attempt to better left to scientists, it is possible that large pro- identify risks before they occur (Figure 3.3). fessional teams can develop their own expertise in Risks in the program can be related to the understanding the injury mechanisms involved. competition schedule, the training program, the Developing and managing an injury prevention program within the team 23

- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

2 6 8 Basic training

Training camp 1 3 5 7 Competition 4

Recovery

1. Change of surface, climate, and running tempo during training camp in Portugal. Athletes should not increase the amount or intensity of training too much. 2. Transition to higher training volume and high intensity of training, combined with several practice games indoors and on artiﬁ cial turf. 3. New training camp to polish form before the competitive season, with occasional practice games on hard grassy playing ﬁ elds on Cyprus. Competition for a spot on the team leads to increases in intensity during competition and training. 4. The beginning of the competitive season. A higher tempo and a packed competitive schedule to which the athlete is unaccustomed. Change of surface to soft grass. 5. High risk of acute injuries during the competition season and a toughpacked competitive schedule at full intensity. 6. Interposed period of hard basic training, strength exercises to which the athlete is not accustomed, and more training for running than usual. 7. The end of the competitive season. Worn out and tired players? 8. Transition to basic training period with running on gravel.

Figure 3.3. Season analysis and proﬁ le. Examples of periods of the season when an increased risk of injuries to a senior-level soccer team exists. Comments concern the risk periods that are circled possibilities for athlete recovery, travel, or other programs—over a season or during a tourna- issues. Although health care personnel responsible ment—is complicated. In other words, season for teams or training groups may have to initiate analysis represents an attempt to predict what this type of analysis, it is strongly recommended may happen—and as such, a form of guess- that the process is done in collaboration with the work. Nevertheless, through discussions between coaching team and, if at all possible, the athletes. coaches, athletes, and medical staff, it is possible Professional contracts deal with athlete availabil- to recognize when athletes are at the greatest risk ity and player associations to advocate maximum of sustaining injuries as a result of the training or levels of competition and schedules. The inclusion competitive programs. Examples of situations in of coaches and athletes will enable them to draw which injury risk is higher are when athletes switch on their past experiences with the team, which is from one training surface to another (e.g., from especially important if there are no injury surveil- grass to gravel) or to new types of training (e.g., at lance data available from the past. If injury sur- the start of a strength training period). Figure 3.3 veillance data are available, the season analysis is illustrates how a team may be at particular risk of an opportunity to review formally the past experi- different injury types at different stages of the sea- ences and discuss whether the injury patterns seen son. Other examples of key program events which may be related to the training and competition could be correlated with injury incidence include: program. For example, a surge in stress fractures • poor sleep due to tight schedule or time on a soccer team may be attributed to a simulta- differences; neous increase in the volume of running and a • change over from heavy preseason training to change from a soft to a hard running surface. competition; Due to the multi-factorial nature of injury • return to play after mid-season pause; causation in sport, identifying risks in sports • beginning of ﬁ nal rounds; 24 Chapter 3

• increased training and competition load participation, their value in injury prevention is associated with representative duties; limited. Unfortunately, this is commonly the case. • change in training volume; Preseason examinations are done for a variety • change of climate, for example, move from a of reasons other than to prevent injuries. Most are summer training camp in “Mediterranean” done for medico-legal reasons; to ensure that the climate to “Northern” climate; participant is healthy. In other words, the objective • selection time for important matches, for is to clear the athlete for participation and verify example, representative schedule (a player may that there is no sign of injury or illness which would hide early symptoms of an injury, thinking this represent a potential medical risk to the athlete (and may prevent selection). risk of liability to the sports organization). There are This type of analysis may be particularly impor- also special cases, for example, when professional tant to avoid overuse injuries. The analysis is teams trade players, where the purpose of the medi- based on the idea that the risk of injuries is greater cal screening exam is to protect their investment. during transitional periods and that each stage It follows from this that the general screening has certain characteristics that may increase risk. examination may include a number of different The risk profi le usually varies from sport to sport, conditions, such as: which underlines how important it is for a medi- • Musculoskeletal injuries cal staff to be intimately familiar with the charac- • Cardiovascular disease and risk teristics of the sport they cover. • Asthma and pulmonary function Based on the principles of risk management, once • Eating disorders a particular element in the team’s program has • Cognitive defi cits related to mild traumatic been identifi ed to represent a high risk for injury brain injury. there are two possible solutions: (i) risk acceptance The factors included in the general screening and (ii) risk mitigation. The coaching staff may examination can be tailored to the sport in ques- decide that this particular element is unavoidable, tion, by focusing on conditions known to be partic- critically important to the success of the team, and ularly prevalent (e.g., low back problems in rowers, therefore must be accepted. However, this is not a eating disorders among female gymnasts, pulmo- decision that should be taken without those at risk, nary function among cross-country skiers) or where that is the athletes. If a high risk is identifi ed, the the physical requirements of the sport implies a coaches should not decide to accept it on behalf of higher risk of certain conditions (e.g., Marfan’s syn- the players (or anyone) without appropriate con- drome among basketball or volleyball players). sultation. Preferably, it may be possible to reduce Depending on the sport and, consequently, the risk, for example, by a more gradual change in run- profi le of the conditions of interest, screening ning surface than was originally planned. examinations may involve: • Examination by a medical practitioner or Preseason screening: the specialist preparticipation or annual examination • Examination by a physiotherapist or trainer • Completion of surveys or validated question- An obvious responsibility of the medical team is naires regarding the psychology of the player, the medical screening of athletes. Preseason or injury history, expectations, and issues preparticipation examinations are routinely done • Assessment of nutrition and diet on hundreds of thousands of athletes around the • Neuropsychological assessments world every year, in some cases required by sports • Assessment of individual and team skills by regulations, or even by law. However, the value of coaching staff doing routine physical exams on athletes is ques- • Self-reporting of performance defi ciencies by tionable. If done properly, they can represent a key players ingredient in the risk management program of the • Family history, for example diabetes, cardiac team. If they are done simply to clear athletes for disease, and depression. Developing and managing an injury prevention program within the team 25

However, if the purpose is to prevent injuries, the tests to measure relevant risk factors with adequate value of doing routine examinations alone is lim- sensitivity and specifi city can be diffi cult. ited. For screening exams to serve a purpose in risk The second requirement is that if the presence management there are some additional require- of a known injury risk factor is identifi ed, an ments. First, the exam must be designed to iden- appropriate course of action can be taken to con- tify athletes with risk factors relevant to the sport trol the risk. If strength is inadequate, it should in question. Second, there must be a plan to follow be followed up with a strength training program. up athletes with measures intended to reduce risk, If balance is poor, a training program should be if risk factors are identifi ed. Third, the screening designed and implemented to rectify this. This exam and follow-up must be planned and led by might be on an individual level, but could be at the medical and coaching staff of the team. Let us a team level too. The presence of common risk consider each of these requirements in turn. factors across the team might point to failures in The fi rst requirement, that the exam is designed player selection and management, or medical/ to identify athletes with risk factors relevant to the rehabilitation management. sport in question, is rarely met in current practice. The third requirement is that the medical and In fact, in most cases, the same screening exam is coaching staff of the team must be intimately used across sports. This is inappropriate. There can involved in the screening exam and follow-up of be no single recipe for all sports, as injury patterns the results. In community level sport, it may be and risk factors differ signifi cantly. In the follow- tempting for a club or school to enlist the assisting chapters, Chapters 4 through 11, the incidence ance of local sports medicine personnel to screen of the most important injury types across sports their athletes. This is only advisable if they can are described. The same chapters also describe the establish a mechanism to communicate the results main risk factors for each of these injury types. to the team, and there are resources to follow up To design a screening program for one particular athletes with risk factors. Also, the specialist must sport, it is, therefore, necessary to defi ne the key be up to date with screening methods for the sport injury types (based on data from the literature on in question and their interpretation. incidence and severity and preferably also surveillance data as described earlier), and then to defi ne Monitoring “at risk” team members or the key risk factors (for these injuries). Based on team, for example fi tness, technique, this information, the screening exam can be tai- and behavior lored to the sport. Even if the key risk factors have been defi ned, The screening of all players preseason may fl ow a key task remains; to select appropriate methods into within season monitoring of a subset of “at- to screen for these risk factors. Screening methods risk” players. The questions that will be answered should be valid, accurate, sensitive, and specifi c. by this screening include: Are players fi t to resume Valid means that the testing method measures normal local competition following representative the factor you wish to measure. For example, if competition or international travel? Has a player low hamstrings strength is a risk factor for muscle recovered physical capacity following resolution strains, what method should be used to measure of a medical condition; is a player returning too this best? The test is accurate (reliable) means that early following injury or masking symptoms to it will yield the same result each time. A testing continue playing? Is there improvement in a play- method with high sensitivity will identify all player’s technique following identifi cation of a defi cit ers with that factor. A test with high specifi city and a training program? If the preseason screening will identify only players with that factor. If the identifi ed a player with a history of inappropri- sensitivity is poor then an injured player might be ate on- and/or off-fi eld behavior, have appropri- permitted to participate in competition, and if spe- ate steps been taken and are there changes? Is the cifi city is poor then a fi t player might be excluded athlete attending rehabilitation sessions? Is the from the competition. Finding valid and accurate athlete wearing the specifi c item of protective 26 Chapter 3 clothing correctly and on all occasions. The same gradually increased load. Progress through the principles apply here, as with preseason monitor- program was allowed when the player was able to ing; the measures need to be valid and reliable, comply with the exercises without pain and swell- and intervention and follow-up is required. ing at the injured site. If a player experienced pain or swelling, he returned to the previous symp- Return to play following injury tom-free level and resumed the progress at a later session. No specifi c time limit or number of repeti- The captain of the Australian cricket team tions were set for the progress, but coaches were responded to a media inquiry as to whether a spe- instructed to evaluate symptoms both when exer- cifi c player was returning to a competition too cises were performed as well as the day after. The early following injury by saying that the player fi nal step was return to competitive play, and an was fi t, that the team did not wish to fi eld an unfi t injured player was not eligible for fi rst team selec- player as he would be less competitive, and the tion until he had been able to participate fully in player did not wish to hurt his chances of further team training without pain and swelling at the selection by playing poorly due to injury. It is clear injured body site. The required number of pre- that it is in the team’s interest for all members to match training sessions varied based on the sever- be fi t prior to their complete return to competi- ity of the injury. tion. The team, in its broad context, can foster a This study illustrated that it is possible to estab- culture whereby safety is paramount. A player will lish programs to guide return-to-play decisions in clearly perform to their best and over a longer a structured manner, and that such programs are time (seasons) if injuries are managed well. The benefi cial in preventing reinjury. At lower levels team can let it be known that players’ positions in of play, building relationships with the local doc- the team are not in jeopardy while they are recov- tors and physiotherapists can assist in establish- ering from injury. Unfortunately, this is often not ing injury management systems, but this requires the case. more than just providing easy access for injury Supervised injury management programs are assessments and emergency care. very helpful, and can be established even at the Specifi c guidelines for return to play are being community and youth levels where resources are published, challenged, and revised continuously. limited. A recent study from Swedish amateur soc- In the area of mild traumatic brain injury, where cer illustrated this (Hägglund et al., 2007). Their there remains controversy over the “right” time to program was implemented by team coaches and return to play, the process of making that decision consisted of information about risk factors for rein- is evidence-based (McCrory et al., 2005). Similar jury, rehabilitation principles, and a 10-step pro- evidence-based guidelines are being developed for gressive rehabilitation program including return other injury types. to play criteria. An analysis of their data showed a 66% reduction in reinjury rate in the intervention Education regarding injury group compared to a control group for all injury management and prevention locations and a 75% for lower limb injuries. The 10-step rehabilitation program was intended Educating the team, including the medical and to serve as a guide for the coaches with structured coaching staff, regarding injury management and assessment during the functional rehabilitation of prevention is necessary. This will at least raise players and to assist in return to play decisions. awareness of specifi c topics, such as symptoms Although the program was designed primarily for that might be related to concussion, and may lower extremity injuries, coaches were instructed assist in compliance with injury management and to use it for all injuries. The program was intro- injury prevention programs. Specifi c sessions can duced to injured players when they were able be conducted preseason and within season. A pre- to walk without limping and without pain. The season session provides an opportunity to present program contained various exercises with a a summary of the fi ndings from the previous Developing and managing an injury prevention program within the team 27 season’s injury surveillance program, observations risk of head and spinal injury is suffi cient to war- from other groups or sports, injury prevention rant making emergency equipment easily available, initiatives in the new season, and an overview of for example, to immobilize and transport athletes, the injury management procedures for the team. and possibly the presence of a trained emergency The preseason session permits discussion and physician over and above the basic level of medical debate on injury management and prevention, support required by the team or teams at the event. with opportunities for all members of the team The emergency management plan will address peo- to contribute. The rules may have been changed ple, equipment, and processes. Training and prac- since last season or substantial changes made in tice are essential for the successful implementation equipment and facilities, the background to these of an emergency management plan. changes and the implications for the team can be presented. During the season, opportunities arise Coordination of injury risk management in team meetings to present updates and remind- ers on relevant topics. The need may arise to run All the activities described in this section could be education sessions within season prior to embark- bundled together into a safety management sys- ing on an international tour or before a tourna- tem. This requires coordination and planning. The ment. All the activities described here and in other system can also be audited for compliance and sections of this chapter assist in developing a safety completeness. The process requires: culture in the team. 1. Assessing the team’s needs 2. Setting goals and objectives Identifi cation of emergency 3. Development of policies, strategies, programs management requirements and actions aimed at achieving goals 4. Implementing programs and policies, including Emergency management is an integral part of education risk management. Emergency management can- 5. Providing resources to implement programs not prevent the initial injury, but it can prevent 6. Establishing a system for review and evaluation subsequent injury and reduce the level of impair- Each stage needs to be documented. The activi- ment. There are some very good documents on ties presented so far in this section feed into this emergency planning and management in sport process, especially injury surveillance. Within this (see Chapter 14 for details on coverage for large system responsibilities are defi ned for everyone in events). The fi rst step is to identify the team’s the team. The implementation of a safety man- requirements. Again, injury surveillance and risk agement system can promote a cycle of contin- assessments will identify the nature and extent of ued improvement leading to injury reduction and the emergency management responses required. possibly on fi eld improvements. Ideally a team Common emergencies are spinal injury, head approach is taken and a small management group injury, heat stress, and cardiopulmonary disease. established with representation from athletes, The appropriate level of specialist medical care coaching, and medical staff. This is consistent with required at the venue for large events is discussed the statutory requirements for occupational health in Chapter 14. For smaller events it may be appro- and safety committees in large places of work. In a priate to ask whether the injury risk is greater than recreational football club, this would be best done in day-to-day living. While there might be a risk of for the club, or if the club is suffi ciently large, for spinal injury or heart attack in a junior tennis tour- defi ned age groups or division, for example, youth nament, it is probably not necessary to have spe- and seniors. The seasonal nature of sport pro- cialist care on-site. A level of medical coverage and vides a natural opportunity in the off-season to a plan for obtaining specialist care if necessary is review and evaluate the injury risk management required; that is, a list of phone numbers for ambu- program. Revisions can be implemented during lances and local doctors. In contrast, in all contact preseason training and competition. The review sports, high velocity sports, and martial arts, the process must consider the resources available and 28 Chapter 3 methods for increasing those resources, for exam- for goal posts, for example. However, checking ple applying for funds, fund raising, or donations, whether the padding extends to a suffi cient height are useful avenues to explore. on the posts can be done. There are some gaps in facility and equipment specifi cations, for example, the International Ice Hockey Federation provides Equipment and facilities very clear guidelines and advice regarding the development of an ice hockey arena, but details International and national standards for of what constitutes “protective glass” and “pad- equipment and facilities ding” are unclear. The International Gymnastics Federation (FIG) provides guidelines regarding size There are numerous national, international, and and stiffness of crash mats and equipment design. sport specifi c equipment and facility standards and guidelines. Examples are: Behavioral adaptation • Helmets: National Operating Committee on Standards for Athletic Equipment (NOCASE); Behavioral adaptation or risk compensation are Canadian Standards Association (CSA); American terms which have been used to describe a possible National Standards Institute (ANSI), Snell change in behavior in an athlete when they use Foundation; Standards Australia (SA); and protective equipment. The theory is that the per- International Standards Organisation (ISO) son will assess the level of risk and, if they assess • Playing surfaces: ASTM International and the that the protective equipment reduces that risk, International Association for Sports Surfaces they will simply undertake more extreme activi- Science ties to return the risk to a level they are comfort- • Shin guards: NOCSAE able with. Whether this theory is true generally or • Gymnastics facilities and crash mat only for some individuals remains unknown and characteristics—the Federation Internationale de it is controversial. Regardless, athletes should be Gymnastique informed and educated about the injury risks in Research shows that there are differences in the sport and the known effectiveness and limitations performance of equipment that meets the same of protective equipment and other controls; as standard. The reality is that equipment stand- described earlier. The results of studies of the effec- ards set minimum performance requirements and tiveness of sports equipment in preventing injury some products might just meet these, while others are being published regularly. Further, if an athlete exceed the requirements and offer more protection appears to become more reckless wearing protec- to the user. There may also be no requirement in a tive equipment, the coaching staff should moni- country that a specifi c piece of equipment meets tor this and intervene. Ideally athletes should be a relevant standard to be offered for sale. Where trained while wearing protective equipment so possible, a team should seek further information that they become familiar with the limitations. prior to deciding on equipment. The team or club With some equipment the safety performance is in a much better position to inquire about this can compromise athletic performance. For exam- than an individual and should advise the athletes ple, ideally ski bindings will release at a load less or their families accordingly. than that fracturing the tibia. If the bindings are In youth and community team sport deleterious set with a very large margin of safety, they may situations arise with equipment when the “one release when a skier is safely executing a success- size fi ts all” approach is taken. Sizing and good fi t ful high-speed turn. If the bindings are set not to are very important. Therefore, the team kit should release easily, the same skier may end up execut- contain equipment that covers the sizing require- ing the turns successful but during an accident ments of the whole team. suffer serious lower limb injury. Consideration for Surprisingly, standards do not exist for some experience, performance, skill, and competition equipment. There is no standard for padding level is required. Developing and managing an injury prevention program within the team 29

Inspection and maintenance of Hägglund, M., Waldén, M., Ekstrand, J. (2007) Lower facilities and equipment reinjury rate with a coach-controlled rehabilitation program in amateur male soccer. A randomized The issue of duty of care arises when facilities controlled trial. American Journal of Sports Medicine 35, and equipment are discussed. All members of the 1433–1442. broad team are responsible for the equipment and McCrory, P., Johnston, K., Meeuwisse, W., Aubry, M., Cantu, R., Dvorak, J., Graf-Baumann, T., Kelly, J., facilities. Certainly it is not possible for a player to Lovell, M., Schamasch, P. (2005) Summary and re-surface an area, but the player might alert team agreement statement of the 2nd International management to those concerns. Conference on Concussion in Sport, Prague 2004. The facilities and equipment (fi xed and mobile) British Journal of Sports Medicine 39, 196–204. can be inspected regularly to identify hazards and compliance with the relevant standards or guidelines. Damage or wear and tear might create haz- Further reading ards for players and offi cials. A protocol for routine inspection of facilities and equipment should be a part of a risk management plan. Organizations Australian Master OHS & Environment Guide, 2nd Ed such as FIS provide guidelines for the set up and (2007) CCH Australia inspection of facilities used in FIS events. There AS/NZS 4360:2004 Risk management and HB 436:2004 (Guidelines to AS/NZS 4360:2004) Risk Management are also private contractors and technical organi- Guidelines Companion to AS/NZS 4360:2004, SAI zations that offer services to measure facility per- Global. formance, for example friction, impact energy Caine, D.J., Maffulli, N. (eds.). (2005) Epidemiology of attenuation, and thermal properties. pediatric sports injuries. Individual Sports. Medicine of Sport Science 48. Federation Internationale de Gymnastique http://www. Training fi g-gymnastics.com/ International Ski Federation http://www.fi s-ski.com/uk/ As stated earlier, it is important that teams are home-page.html trained to use equipment. Training might consist Maffulli, N., Caine, D.J. (eds.) (2005) Epidemiology of of advising on the level of protection offered by pediatric sports injuries. Team sports. Medicine of Sport particular equipment, the correct use, adjustment Science 49. and care of equipment, and equipment misuse. McClure, R., Stevenson, M., McEvoy, S. (eds.) (2004) As a note of warning, it might be necessary to The Scientifi c Basis of Injury Prevention and Control. IP explain the limits of protection conferred by spe- Communications, Melbourne. McIntosh, A.S., Janda, D. (2003) Evaluation of cricket cifi c equipment and provide feedback or supervi- helmet performance and comparison with baseball and sion with fi t and adjustment. Training drills while ice hockey helmets. British Journal of Sports Medicine 37, wearing equipment are important too as they help 325–330. athletes become accustomed to wearing equip- National Operating Committee on Standards for Athletic ment and issues, such as communication, can be Equipment http://www.nocsae.org/ identifi ed and resolved. Peltz, J.E., Haskell, W.L., Matheson, G.O. (1999) A comprehensive and cost-effective preparticipation exam implemented on the World Wide Web. Medicine and Science in Sports and Exercise 31, 1727–1740. References

Anon. (2000) The British Olympic Association’s position statement on athlete conﬁ dentiality. Journal of Sports Science 18, 133–135. Fuller, C.W. (2007) Managing the risk of injury in sport. Clinical Journal of Sport Medicine 17, 182–187. Chapter 4 Preventing ankle injuries Jon Karlsson1, Evert Verhagen2, Bruce D. Beynnon3 and Annunziato Amendola4

1Professor of Sports Traumatology, Department of Orthopaedics, Sahlgrenska University Hospital, Göteborg, Sweden 2Department of Public and Occupational Health, EMGO-Institute, VU University Medical Center, Amsterdam, The Netherlands 3 Department of Orthopaedics and Rehabilitation, McClure Musculoskeletal Research Center, The University of Vermont, VT, USA 4Department of Orthopaedic Surgery and Rehabilitation, University of Iowa Sports Medicine Center, University of Iowa, Iowa, USA

to stretch beyond their normal range in an abnormal Epidemiology of ankle injuries position, leading to overstretching or rupture of one in sports or more lateral ankle ligaments. It is not surprising that particularly contact sports, indoor sports, and Ankle injuries sports with a high jump rate have a high incidence rate of ankle sprains (Table 4.1). In volleyball it has It is well known that across all sports the most com- even been estimated that half of all acute injuries are mon location of injury is the ankle. It has been esti- ankle sprains. mated that about 25% of all injuries across all sports In general an ankle sprain causes an individual to are ankle injuries (Tik-Pui Fong et al., 2007). Thereby, refrain from sports participation at least for 1 day. it is important to have a clear focus on ankle inju- A side effect of an ankle sprain is the high risk of ries, the associated risk factors, as well as the meth- re-injury to the same ankle, which can result in dis- ods of prevention. Ankle injuries can be classifi ed as ability and can lead to chronic pain or instability either acute or chronic, with ligamentous injury by in 20–50% of these recurrent cases. The relatively far being the most common acute diagnosis. About high rate of ankle sprains across all sports and the 85% of all ankle injuries involve the lateral ankle potentially negative consequences of ankle sprains ligaments, that is, ankle sprains. Chronic injuries on future sports participation, motivates specifi c are often related to, or sequelae of acute sprains, or attention for preventive measures against this type overuse syndromes of the surrounding soft tissues. of injury. In view of the predominance of ankle sprains, this chapter will focus on ligamentous injuries, in particular lateral ligament injuries. Sport-specifi c injury The lateral ankle ligaments are the more impor- epidemiology: soccer tant structures that hold the ankle bones and joint in position. In doing so, these ligaments protect the It has been estimated that 50–60% of all sports inju- ankle joint from abnormal movements, especially ries in Europe and, as a result, 3.5–10% of all hospital from excessive twisting, turning, and rolling of the treated injuries are related to soccer. Soccer has also foot. It is these movements that cause an ankle become one of the fastest growing sports in North sprain, that is, when the foot twists, rolls, or turns America. Because of its popularity, soccer injury epi- beyond its normal motions. This causes the ligaments demiology has been the topic of frequent reports. Table 4.1 summarizes the fi ndings of several published studies on soccer injuries. The lower extrem- Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing ity was the most common site of injury regardless of ISBN: 9781405162449 the skill or age level of all the participants, ranging

30 Preventing ankle injuries 31

Table 4.1 Risk of ankle sprains in different sports. The numbers reported are average estimates based on the studies available.

Sport Competition Overall Rank2 Comments incidence1 incidence1

Team sports Volleyball 1.8–5.5 0.6–2.0 1 (32–49%) Soccer 0.4–26.7 0.1–5.0 1 (15–41%) Team handball 1.32 0.4–1.6 2 (11–14%) Basketball 1.2–5.4 0.9–4.7 1 (13–27%) American Football 5.0–13.0 0.5–3.9 2 (12–21%) Australian Football 3.9–4.9 1.3–2.3 3 (9–14%) Indoor soccer 10.1–10.3 NA 1 (19–25%) Individual sports Orienteering 3.8 0.82 1 (27–32%) Badminton NA 0.6 1 (19–24%) Gymnastics NA 0.06–0.31 2 (11–21%)

1Incidence is reported for adult, competitive athletes as the number of injuries per 1000 h of training and competition. 2Rank indicated the relative rank of ankle within each sport, as well as the proportion as a percentage of the total number of acute injuries within the sport. NA: Data not available.

65–90% of all recorded injuries. Ankle injuries were Location of injury is overwhelmingly found in the most common in all studies, ranging 15–41% of the lower extremity and the greatest prevalence of all injuries, and the majority of these were sprains. injuries, one-third, is around the foot and ankle. Orienteering/long distance running are variants American football and rugby of running sports. Running is the major training exercise for orienteerers and likely the reason One of every fourteen teenager presenting to the for the majority of injuries are from overuse. In emergency room following a traumatic event has a prospective study of elite orienteerers, 94% of a sports-related injury, and American football is the injuries occurred during running and 53% of the most common precipitating athletic activity in those occurred while running on uneven ground. the United States. In a recent review of high school Almost 90% of the total injuries occurred in the and collegiate football injuries, the most com- lower extremity and almost two-thirds of the total monly injured body sites were the knee and lower injuries occurred in the lower leg, ankle, and foot leg/ankle/foot. The majority (ϳ70%) of lower leg/ regions. The most common traumatic injury was ankle/foot injuries were to the ankle (15.2% of all a sprain of the ankle and usually occurred during injuries). The most common cause of knee and running in forest or uneven ground. ankle injury was ligament sprains (53.2% for knee and 88.0% for ankles). Rugby has a larger incidence Basketball of head, neck, and spine injuries as well as fractures. Ankle sprains represent 9.1% of all injuries. In numerous studies in basketball players, professional and amateur, the lower extremity was most Running, jogging, and hiking commonly injured; the ankle and sprains as the most common type of injury. The ankle and knee Running has become one of the major recrea- injuries were also the most severe with the greatest tional and competitive sports. Generally, injuries time lost from participation. An alarmingly high encountered in these sports are overuse or repeti- rate of residual symptoms, up to 50%, is seen in tive stress type from accumulative impact loading. athletes with a history of ankle sprains. 32 Chapter 4

Volleyball this is that disruption of a ligament compromises an important biomechanical stabilizer of the In most studies involving high level volleyball ankle and creates partial deafferentation that can players, the ankle is the most common overall site compromise neuromuscular control of the ankle of injury, with ankle sprains as the most common (Hertel, 2000). Studies of soccer athletes, volleyball injury. Most of the injuries occur at the net, with athletes, basketball athletes, and military recruits ankle sprains resulting from landing on another undergoing basic training found that they were all player’s foot. at a twofold risk for lateral ankle ligament injury after suffering a prior ankle injury. It is important Gymnastics to identify these players with previous injury and/ or impaired neuromuscular control, in order to Women’s gymnastic injury rates have consistently provide proper treatment and medical guidance. been among the highest seen across sports. The lower extremity accounts for one-half to two-thirds of all reported injuries in gymnastics. Sprains and strains Postural sway appear to account for over half of these injuries. Postural sway is closely linked to a previous ankle Although many reports stress that the ankle is one sprain occurrence (Willems et al., 2005a, b). A sprain of the most commonly injured joints in gymnastics, affects neuromuscular control of the ankle, sub- one study comparing gymnasts to age-matched consequently leading to an increased risk of re-injury. trols found that the prevalence of ankle complaints Recognizing that an athlete’s center of gravity con- was the same, 27% in both groups. stantly changes position during upright posture (i.e., postural sway), and that this is under the con- Racquet sports trol of both the central and the peripheral nervous system, many different approaches have been used Common racquet sports include tennis, badminton, to characterize postural sway and this outcome squash, and racquetball. Although one may associate appears to be related to the risk of suffering an ankle these activities with upper extremity problems, for injury. Postural sway is generally characterized in a example, tennis elbow and wrist pain, from epidemi- practical approach that involves measurements of ological studies available, the lower extremity is still the duration of time that a subject can maintain a one of the most common sites of injury. Most pub- single leg stance without touching down to recover lished studies indicate that over 50% of injuries in balance. Athletes, who are able to maintain a sin- these sports occur in the lower extremities. Of these, gle leg stance for at least 15 s are considered to have ankle sprains appear to be the most common injury. normal posture, whereas those that touchdown to In the constrained racquet sports, such as racquetball regain balance within the 15 s test are considered to and squash, which have a signiﬁ cantly higher rate of have abnormal posture (Figure 4.1). Several studies facial injuries, ankle sprains are the most frequent have shown that athletes with abnormal posture of the non-facial injuries, accounting for more than suffer more ankle sprains as compared to athletes 25% of total injuries. with normal sway.

Gender Key risk factors: how to identify athletes at risk Among female athletes, the risk of suffering a ﬁ rst time ankle ligament tear is associated with Previous ankle ligament sprain the sport they participate in. Several studies have shown that the risk of suffering a ﬁ rst time ankle Of the many risk factors suggested for lateral ankle ligament injury appears to be highest for female ligament sprains (Table 4.2), perhaps the most basketball athletes, who are estimated to have a important is a previous sprain. The rationale for 25% higher risk than male basketball athletes. Preventing ankle injuries 33

Table 4.2 Internal and external risk factors for ankle sprains in different sports. The numbers reported are average estimates based on the studies available.

Risk factor Relative risk1 Evidence2 Comments

Internal risk factors Previous ankle sprain 2 ϩϩ Increased risk for recurrence during 12 months post-injury Postural sway NA ϩ Gender 125 ϩ Risk is higher for females Range of motion of the ankle NA ϩ Height and weight NA ϩ Anatomic foot type NA ϩ Foot width NA ϩ Generalized joint laxity 0 No known association Ankle joint laxity NA ϩ Muscle strength NA ϩ Limb dominance NA ϩ External risk factors Shoe type ϩϩ No association Play in game versus practice 2–44 ϩϩ Higher risk during games Player position 1–5 ϩϩ Relative risk depends upon sport

In contrast, there is evidence that suggests the risk some benefi t in terms of reduction of ankle ligament of suffering repeated ankle ligament sprains is sim- injury risk by participating in stretching programs ilar for females and males for jumping sports such that are designed to increase dorsifl exion motion. as volleyball. Additional research that focuses on the effect of gender on the risk of suffering a fi rst Height and weight time ankle ligament injury is needed in other high Height and weight have been implicated as risk risk sports that produce ankle ligament injuries. factors because when a athlete is in an at-risk posi- Range of motion of the ankle tion for inversion ankle trauma, an increase in either height or weight proportionally increases A decrease in dorsifl exion range of motion of the the magnitude of the inversion torque that must ankle has been associated with an increased risk of be resisted by the ligaments and muscles that span suffering an ankle sprain (Willems et al., 2005a, b; the ankle complex; however, there is little consen- de Noronha et al., 2006). The relationship between sus in the literature with regard to how these out- decreased dorsifl exion and increased risk of ankle comes are related to risk of ankle ligament injury. ligament injury may be produced by a tight gas- There are studies that demonstrated that height and trocnemius muscle–tendon complex, which could weight are not independent risk factors for ankle place the ankle–foot complex in greater plantar sprains. In contrast, from soccer, American foot- fl exion during activity. This would unlock the talus ball, and the military there are other studies, report- from the ankle mortise, and place the ankle at an ing that athletes of greater height and weight (and increased risk of abnormal inversion and internal increased body mass index (BMI)) are at increased rotation. This fi nding suggests that athletes that ankle sprain risk. The different fi ndings between the are predisposed to ankle ligament injury because of investigations may be explained, at least in part, by decreased dorsifl exion range of motion may realize the different sports which were studied. 34 Chapter 4

are most likely produced by different study designs, differences in the sample sizes, the different sports studied, or the methods used for data analysis.

Foot type, foot size, and anatomic alignment of the lower extremity

Anatomic foot type, when classifi ed as pronated, supinated, or neutral, does not appear to be a risk factor for ankle sprains. It is important to point out that the use of the classifi cation system, which characterizes anatomic foot type as pronated, supinated, or neutral, may be inadequate for identifying abnormalities in foot biomechanics. Indeed, the defi nitions of different foot types are vague and not scientifi cally based. This approach has not been related to musculoskeletal abnormalities, as it does not have the specifi city and sensitivity to identify abnormalities in foot biomechanics, and it is evaluated while a subject is standing barefoot (sometimes in a laboratory) and not during a situation when the lower extremity is at risk for injury. Therefore, specifi c and sensitive measurements of foot contact mechanics that can be used during dynamic, at-risk activity need to be developed and used to determine if they are capable of identifying an ankle at risk for an inversion sprain. Studies revealed that dynamic pes planus, pes cavus, and increased hind foot inversion are associated with an increased risk of suffering a sprain of the lateral ankle ligaments (Morrison & Kaminski, 2007). The same goes for an Figure 4.1. Balance test. The patient stands on one leg increased foot width, which can be explained, at with the other leg slightly fl exed and hanging straight least in part, by the fact that during an inversion down. He crosses his arms over his chest and looks at a injury, an increased foot width is associated with an point straight ahead. If he can balance for 1 min with his eyes open, he closes his eyes and balances for another 15 s increased moment arm and corresponding inversion moment in comparison to a narrow foot. Limb dominance Ankle joint laxity and generalized Limb dominance has been implicated as a risk factor joint laxity for lower extremity trauma because most athletes place a greater demand on their dominate limb To most involved in diagnosis and treatment of and as a consequence produce an increased fre- ankle injuries, increased laxity of the joint would be quency and magnitude of moments about the knee considered a “sure bet” as a risk factor for an ankle and ankle, particularly during high demand activi- injury, because it indicates that a soft tissue restraint ties that place the ankle and knee at risk. However, may have been compromised along with its con- the literature is divided with regard to limb domi- tribution to stability (laxity restraint) and neural nance as a risk factor for suffering an ankle liga- intervention of the ankle complex. However, the ment sprain. Contrasting fi ndings in the literature literature presents confl icting fi ndings with regard Preventing ankle injuries 35 to the relationship between joint laxity and ankle of athletic shoes and how they are related to ankle ligament injury. The discrepancy between the avail- injury. Specifi c characteristics of the shoe may either able evidence may derive from the use of the clini- reduce the risk of injury (e.g., certain design charac- cal examination and a grading system to evaluate teristics may provide increased proprioceptive input) joint laxity. Indeed, accurate and reproducible clin- or increase the risk of injury (e.g., restricted ankle ical examination is not easy. Another reason might range of motion, abnormal foot-shoe, and shoe- be an inadequate sample size with too few subjects surface traction, or increase the inversion moment with increased ankle laxity included. It is impor- arm about the ankle complex). There is little infor- tant to appreciate that increased ankle joint laxity mation on the effect that different characteristics may be highly correlated with prior ankle ligament of athletic shoes have on the risk of ankle injury. It injury which by itself is an established risk factor is more likely that the newness of the shoe plays a for ankle ligament re-injury. From this perspective, more important role than its height in preventing if a study includes joint laxity as an outcome, an ankle sprains. increase in this outcome may simply serve as a sur- rogate for prior injury. There appears to be a con- Play setting sensus in the literature that generalized joint laxity has no predictive value for ankle sprains. This is the There is a general consensus that across all sports case when considering men and women athletes as the risk of injuries in general is higher during a group, and men and women as separate groups. competition than during training. It seems logical to assume that this also goes specifi cally for ankle Muscle strength sprains. This logical assumption is backed up by sound evidence from soccer, basketball, as well as While most would consider it intuitive that lower volleyball. The main reason for this difference in extremity strength is related to the risk of suffer- injury risk lies in different play modes between ing an ankle ligament sprain, only a few investiga- competition and training. During competition tions have studied this with a prospective design athletes are more prone to take “risks” in order and accurate equipment and there is little consen- to win. During training, logically, taking risks is sus between the studies. An increased risk of ankle minimized and most play consist of short well ligament injuries has been observed for collegiate controlled bouts of sports specifi c drills. In short, female athletes participating in soccer, fi eld hockey, the playing environment during training is more and lacrosse when they have higher peak torque controlled and thereby safer. ratios between the invertors and evertors of the ankle. A study of male physical education students Playing position reported that decreased strength of the muscles that dorsifl ex the ankle was associated with an increased Volleyball athletes are at increased risk when they risk of suffering an ankle ligament injury (Willems play the front row positions, by landing under the et al., 2005b). In contrast, a study of male military net after a jump for a spike or block. However, in recruits found no relationship between muscle sports such as basketball and soccer which also strength and the likelihood of suffering an ankle involve jumping, planting, and cutting, the risk of ligament injury. ankle ligament injury appears to be similar between positions. Nevertheless, at least for soccer, it is Shoe type known that most injuries occur when an athlete has to play outside his or her usual playing position, An extrinsic risk factor, which has been well investi- for example, a striker making a defensive action, or gated, is the shoe type. Although most would agree a defensive player moving toward the opponent’s that current athletic shoes offer limited support to goal. Therefore, while in certain sports ankle sprain an ankle in response to inversion trauma, it is impor- risk may not be directly associated with playing tant to recognize that little is known about the effect position, an athlete at a specifi c playing position 36 Chapter 4 may be so well adjusted to his or her tasks that changing roles on the team increases risk.

Take-home message

In recent years considerable research has focused Anterior on risk factors related to ankle sprains. This has talofibular resulted in a number of potential risk factors, of Posterior ligament which most are surrounded by confl icting fi ndings talofibular from scientifi c studies. The only well documented, ligament and probably by far strongest risk factor for an ankle sprain, is a history of a previous similar injury, especially an injury during the past year. Therefore, it is important to map previous injury and test proprioceptive ankle function by means of a postural sway test. This latter method has been proved to be able to detect athletes at risk. Although preventive Calcaneofibular ligament measures should be advocated to all athletes, especially this subgroup of previously injured athletes Figure 4.2. The lateral ankle ligaments should be targeted with preventive measures, such as proprioceptive training, taping, or bracing. the calcaneofi bular ligament, and the posterior talofi bular ligament (Figure 4.2). When sitting with a relaxed ankle, the ankle Injury mechanisms for ankle sprains tends to hang in a slight plantar fl exed inversed position, that is, the toes are slightly facing the fl oor and pointing slightly inward. This is the “neu- Anatomical and biomechanical tral” position of the ankle. This can also be seen aspects when inspecting worn shoe soles. The initial point Before describing the injury mechanisms leading of impact is on the outside of the heel, showing in to an ankle sprain, a short description of the ankle the fastest wear on that side of the sole. What hap- complex is required. The ankle is a so-called hinge pens is that when walking, in the swing phase the joint, bringing the lower leg (tibia and fi bula) and ankle moves to its “neutral” position. Although this the foot (talus) together. The hinge allows dorsifl ex- is the “neutral” ankle position, it is also a position ion (pulling the ankle up to make the toes face up) that puts the ankle at risk for inversion injuries, that and plantar fl exion (stretching the ankle and make is, ankle sprains. As said, in this ankle position the the toes face down). These movements occur in bony stability provided by talus is low, and most of varying degrees between 50º and 90º. The talus is the laxity restraint is provided by the lateral liga- wider in the front, making it a wedge-shaped bone. ments. Although the ankle is in perfect balance in Due to its shape the talus provides maximum stabil- the “neutral” position, a slight interference moving ity in dorsifl exion but minimal stability in plantar the ankle in to a further plantar fl exed inversion fl exion. Although there is room for some inversion position, results in forces which the lateral liga- and eversion movement (turning the foot inward or ments can’t handle. As a result the ankle forcefully outward respectively), the range of motion of these inverts, which is called an ankle sprain (Figure 4.3). movements is limited. This limitation in movement An ankle sprain results in physical damage to the is primarily restricted by the capsule surrounding lateral ankle ligaments, and is usually classifi ed by the ankle, which is reinforced by both medial and the number of ligaments that are injured. With the lateral ligaments. The lateral ligaments, the area of foot in plantar fl exed inversion, the biggest strain is interest here, are the anterior talofi bular ligament, on the anterior talofi bular ligament. It may not be Preventing ankle injuries 37

blocker(s) across the centerline (Verhagen et al., 2004a). It is well known from several studies that approximately half of all ankle sprains occur when a blocker lands on the foot of an opposing attacker who has legally crossed the centerline. It happens frequently that an attacker getting ready for a spike has to adjust his jump for a set that is too low Figure 4.3. Ankle movement and too close to the net. The resulting momentum leading to an ankle sprain: whilst the foot is plantar fl exed and and jump trajectory takes him under the net. As slightly inverted, the foot is easily long as part of the attacker’s foot touches the cen- further inverted and/or rolled terline this is allowed within the rules of volley- inwards leading to an excessive ball. Unfortunately, for tactical reasons the blocker strain on the lateral ankle ligaments jumps later than the attacker, and may land on the attacker’s foot within this “confl ict zone” under surprising that this is the fi rst ligament to tear dur- the net. This situation accounts for about half ing an ankle sprain. With increasing forces, the next of the ankle sprains in volleyball. Additionally, ligament to tear is the calcaneofi bular ligament, and approximately one quarter of all ankle sprains in rare cases the posterior ligament is also injured. occur when a blocker lands on a teammate’s Based on the mechanism described earlier, it is foot when participating in a multi-person block. not surprising that most sports-related ankle sprains Consequently, middle blockers and outside attack- are a result of landing on other athletes, objects, or ers are at greatest risk for ankle sprain (net posi- uneven surfaces. Even so, this explains (at least in tions), whereas setters and defensive specialists are part) the increased risk after an earlier ankle sprain. at comparatively lower risk (back court positions). As said, a previous ankle sprain results in partial Although in volleyball ankle sprain risk seems deafferentation that can compromise neuromus- to be position specifi c, in sports such as basketball, cular control of the ankle, a proprioceptive defi cit. soccer, and handball which also involve jumping, Ankle proprioception is an important regulatory planting, and cutting, the risk of ankle ligament system keeping the ankle in the safe “neutral” posi- injury appears to be similar between positions. In tion. When one is unable to accurately detect the these sports the different skills and tasks between position of the ankle, its position will easily deviate positions do not vary as greatly as in volleyball. from the “neutral” position. Additionally, the pro- More importantly, players are not divided by a net tective refl exes reacting to a sudden inversion of the and physical contact and jumping within close ankle won’t be able to detect changes in range of range of each other is not uncommon. motion to such an extent that a proper reaction is In soccer, it has been found that ankle sprains possible. The term “feel” should be put into context occur when the players gets hit in a late, sliding here, since the proprioceptive system is regulated tackle, while the foot is being planted on the surface peripherally. In short it is the whole system consist- (Figure 4.4). A laterally directed hit on the medial ing of muscle spindles, nerves, refl exes, etc. that sub- side of the ankle or lower leg will put the ankle in a consciously control ankle movement and position. vulnerable, supinated position, and when the player puts weight on the ankle, this leads to an inversion sprain. In other words, it is not the tackle that Examples from specifi c sports ruptures the ligament, but the fact that the tackle One of the sports in which the events leading to causes the player to land in a vulnerable position. an ankle sprain has been well documented, is vol- In the end a vast amount of sports- and leyball. Nearly all volleyball-related ankle sprains situation-specifi c examples of situations in which result from player-to-player contact. Ankle sprains ankle sprains occur can be given. However, it is occur most frequently at the net, as the result of important to note that every ankle sprain has contact between the attacker and the opposing a single common underlying cause, that is, the 38 Chapter 4

been described is probably associated with rules prohibiting play on dangerous pitch conditions or athletes being aware of these risks. Although seasonal infl uence may lack a scientifi c basis, in male amateur soccer players it has been shown that most ankle sprains occur during the fi rst 2 months of the season (Kofotolis et al., 2007). This is in line with fi ndings that in males low running speeds and low cardiorespiratory fi tness are associated with ankle sprains (Willems et al., 2005b). After the summer break athletes will be less “fi t,” and the level of fi tness will be regained during the course of the season. Therefore, it is advised to pay special attention to ankle sprains at the start of a new season. This can be done for instance by eliminating all external risk factors, by advocating preventive measure use to all players, or by planning training session aimed more at increasing fi tness than skill.

Preventive measures Figure 4.4. Typical mechanism for lateral ligament injury in football: opponent contact to the medial side of the leg, causing the player to put weight on an inverted ankle. Based on the scientifi c evidence on etiology of Illustration reproduced with permission. ©Oslo Sports ankle sprains and the injury mechanisms described Trauma Research Center/T. Bolic earlier in this chapter, a matrix illustrating potential methods to prevent ankle sprains can be cre- athlete’s ankle is forced into a position of plantar ated (Table 4.3). It should be said that although for fl exed inversion after contact with another player, a number of potential ankle sprain risk factors there object, or surface. is (shallow) scientifi c evidence, most risk factors can be established by using common sense. Balls may Identifying risks in the training and wander around the pitch during training, during competition program the winter time the fi eld is harder and other cleats are required, a wet cross-country running track is slippery, three players jumping for a rebound under Little is known about possible seasonal infl uences the basket, etc. Although general preventive guide- on the risk of sustaining an ankle sprain, and the lines based on proven risk factors can be given, meager evidence shows no strong relationships. each situation is different. Therefore, it is recom- This is not completely surprising, while ankle mended to keep track of the ankle sprain causes in sprains occur most frequently in indoor sports with an injury log and perform a subsequent risk analy- a high jump rate like volleyball or basketball. For sis on the acquired data. In this way recurring risks that reason most research focuses on these sports can be ascertained and dealt with accordingly. in which weather conditions have no impact on ankle sprain risk whatsoever. However, by using Rule changes common sense one can think of a number of reasons why during autumn and winter ankle sprain In volleyball most ankle sprains occur under the risk could be infl uenced by weather conditions. net when a player lands on the foot of a teammate The fact that these relational infl uences have never or an opponent after jumping for a spike or block. Preventing ankle injuries 39

Table 4.3 Injury prevention matrix for ankle sprains: drills involving risky situations or even design drills potential measures to prevent injuries. to teach avoidance strategies in high-risk situa-

Pre-crash Crash Post-crash tions (provided the drills are done in a safe way, of course). Following the examples giving earlier, after Athlete Skill Neuromuscular heavy rain cross-country runners should avoid une- Neuromuscular function ven and slippery surfaces during training. During function Rules Rule changes practice soccer players may be instructed to restrict Material External ankle their dueling on corner kicks. Such measures can support drastically decrease overall ankle sprain risk. One can only get injured while participating in sports, and training accounts for the highest exposure. A safe training environment will therefore have a It has been postulated that changing the net-line great impact on injury risk. rule will avoid these collisions under the net. The Nonetheless, from a coaching perspective it is current net-line rule allows a player to cross the undesirable to avoid or modify all “risky” situations line under the net as long as part the foot stays in during training. The avoided or modifi ed situa- contact with the line. Changing this rule to a state tions will most surely come up in an unmodifi ed where a player may not cross or touch the net- version in a competitive setting (e.g., there will be line, will avoid the possibility to land on an oppo- tough air duels after corner kicks). For that reason, nent’s foot. Thereby, an important cause of ankle it is also important to prepare the athlete for the sprains in volleyball will be eliminated. In a pilot risk situations encountered during competition. study where this suggested rule was applied, it was It is the challenge of the coach to fi nd a balance found that too many rallies were stopped due to between the safety of training drills and the true violations of this new rule, and the proposed rule situations encountered in a competitive setting. change was discarded. Nevertheless, the rule could be applied during practice – both to reduce risk and Improving player skills to teach players techniques to win the ball without entering the potential confl ict zone under the net. With regard to high-risk situations in volleyball, a Another example of a rule change intended to preventive program that included improvement of prevent ankle injuries is from soccer, where tackles volleyball skills was evaluated (Bahr et al., 1997). from behind result in an automatic red card and Players were taught specifi c jumping and landing expulsion from the game. Recent data suggest that techniques that prevented them to land in the red cards should also be considered for late sliding “confl ict zone” under the net. Two seasons later tackles against the lower leg. there was a twofold reduction in the incidence of It is obviously not always possible to develop ankle sprains. In addition it was shown that the effective rule changes that reduce injury risk. number of ankle sprains due to player contact in However, when keeping track of ankle sprain causes the “confl ict zone” was decreased signifi cantly. in an injury log one may identify situations where Although this example stems from volleyball, this ankle injuries occur more frequently. One may con- shows that the overall idea to teach players (on clude for instance that ankle sprains occur mostly how) to avoid risky situations is potentially very on a wet and uneven surface in cross-country run- effective. Again an injury log may provide the ning, or in the goal area after a corner kick in soccer. information needed to develop skill training for Formal rule changes to avoid risky situations may specifi c sports and specifi c situations. not possible, because they change the nature of the It should be noted that a difference in approach game as in the previous volleyball example. Still, is needed between older (experienced) and younger once established, players can be taught to recognize athletes. Experienced athletes have been participat- and avoid risky situations during training. Adjusted ing in sports for a relatively long time, and learning rules can be applied during training, one can avoid new “safer” skills requires an alteration of previously 40 Chapter 4 gained skills that are executed, by a large part, auto- tape adhesion. If wanted, heel and lace pads can be matically. Younger athletes have not acquired sports applied to areas of high friction (e.g., the dorsum of specifi c skills to such an extent. Thereby, it is easier the ankle and the distal Achilles tendon) to prevent to teach younger players safe skills and to ensure blisters. they employ these skills in true sports situations. Braces Taping The concept of ankle bracing evolved from ankle Probably the most well known and already widely taping. Braces are currently being used instead of preventive measures against ankle sprains are tape traditional taping by many athletes at all levels of and braces. Review of the prospective studies of competition. They offer several advantages in that the effect of taping and bracing on reduction of they are self-applied, reusable, and readjustable. ankle sprains reveal a consistent fi nding; athletes In the long run, they are also more cost-effective with a history of ankle sprains, who regularly use a than taping. A brace will be a one time expense brace or tape experience a lower incidence of ankle lasting a couple of seasons. Tape is not reusable, sprains (Quinn et al., 2000). and every time new rolls of tape must be pur- Taping is a form of strapping that attaches tape chased. Although braces are considered to have to the skin in order to physically maintain a cer- important advantages over tape, many athletes do tain joint position. Taping of the ankle is the ear- not feel as comfortable or as stable wearing braces, liest prophylactic measure used to prevent ankle which can be a disadvantage to treatment. Braces sprains. What one also does is stimulate additional also can become torn or lost and require replace- nerve receptors on the ankle surface and to avoid ment. Additionally, there is a common belief that any excessive ankle movements leading to an ankle braces affect performance by restricting too much sprain. ankle movement. Although this has never been Over time a large variety of taping methods has shown in scientifi c studies, it is for instance likely been developed. Additionally, many different types that the use of an ankle brace alters the (feeling of athletic tapes are manufactured, which can be of) ball contact in soccer. Thereby, the advocation divided into a non-elastic and elastic variant. For of braces in soccer may result in non-compliance, standard ankle application, the choice of tape is 3.8 and it would be better to recommend the use of or 5.1 cm white porous athletic non-elastic tape. ankle tape. The two most commonly used and widely Braces come in three different basic varieties accepted methods are the so-called basketweave (Box 4.2). These varieties may go by different names, method and the fi gure-eight method (Box 4.1). but in general one can speak of the following: Other taping methods are also available, as well as 1. Ankle sleeves: These provide no stability but variations on the methods explained here. Applying provide compression and can be used for prevention tape can be diffi cult and, more importantly, frustrat- due to their positive proprioceptive (balance and ing at fi rst. With a bit of practice one will be able to positioning) effect. These braces do not limit normal properly tape an ankle within a few minutes. ranges of motion of the foot and ankle. One of the greatest benefi ts of taping is that one 2. Non-rigid ankle braces: These come in two can adjust the method of taping to the needs of the basic types (a) with an elastic sleeve with athlete. This starts with the preparation of the skin. “wrap-around” straps, and (b) nylon, canvas, or The most common preparation is to clean and dry neoprene lace-up brace with elastic wrap around the lower leg, ankle, and foot. A layer of pre-wrap is straps. Both provide minimal stabilizing effect applied to the ankle. Some athletes prefer to shave but assist with proprioception. Many of these the hair around the ankle, and to have the tape braces can be uncomfortable. Fortunately, there is applied directly to the skin. Whatever the wishes of an abundance of various types and fi ts available, the athlete, a quick drying adherent is recommended making it possible for each athlete to fi nd a and may be sprayed onto the skin to allow for better comfortable model. Preventing ankle injuries 41

Box 4.1 Common methods for taping the ankle

General guidelines to the fi rst piece of tape—it should fall right over the knobby 1. Hold the tape between the thumb and the index fi nger of anklebone that juts out. each hand with little to no gap between the thumbs. Quickly pull the hands in opposite directions to tear off a piece of tape. 2. Avoid wrinkles in the tape, these can lead to blisters and discomfort. Once applied the tape will be stuck solid, therefore one must smooth the tape while it is being applied. 3. Learn to use the angles naturally supplied by the ankle. When forcing tape in a specifi c direction it does not want to go will create wrinkles and results in a less effective application. 4. In general, tape strips should overlay each other by about Step 5: Wrap a fourth piece of tape around the heel, running just one-half the width of the tape. Each area should be covered by above and adjacent to the second piece of tape, with the ends two layers of tape. Uncovered areas within the taped ankle lead again heading for the toes along both sides of the foot. You now to blisters. have the basic structure for the “basket weave”—overlapping 5. Do not use excessive force when applying tape. Constriction pieces of tape that wrap around the heel, extend to the toe, of blood fl ow is possible when tape is applied too tightly. wrap under the heel, and climb up to the ankle.

The basketweave method Step 1: Wrap one piece of athletic tape under the heel of the foot and bring both ends up the ankle to either side of the leg. The tape should form a “U,” like the stirrup on a horse’s saddle.

Step 6: Apply about eight more pieces of tape in this manner— four adjacent strips of tape that wrap around the heel pointing toward the toes, and four adjacent strips that wrap under the heel and head up the ankle. Alternating between strips that run along the foot and strips that run up the ankle will give you a weave that limits mobility and supports the entire ankle. Step 2: Afﬁ x the tape to the skin just behind the knobby bone that juts out on either side of the ankle, pressing the tape ﬁ rmly along the little groove behind the bone.

Figure-eight method with heel lock Step 1: Place foot in the dorsifl exion position. Step 3: Wrap a second piece of tape around the base of the Apply pre-wrap from mid-foot to the base of the gastrocnemius/ heel, bringing the ends of the tape along either side of the foot, Achilles tendon junction. heading for the toes. It should form a 90º angle with the fi rst Maintain foot in dorsifl exion. piece of tape.

Step 2: Apply two anchor strips at the junction of the Step 4: Wrap a third piece of tape under the heel and up either gastrocnemius/Achilles tendon, over-lapping one-half to a side of the foot and ankle in the same manner as you wrapped one-third. Angle tape down and back slightly to avoid gapping. the ﬁ rst piece of tape. Position the tape so that it runs adjacent Apply one anchor at the mid-foot, making sure to place distal to

(Continued) 42 Chapter 4

Box 4.1 (Continued)

the head of the fi fth metatarsal. *Placing directly over the head Step 7: Begin to apply the “fi gure eight.” Starting on the dorsal of the fi fth metatarsal can cause discomfort. aspect of the foot, move medially down the inside of the foot, across the plantar surface, pulling up on the outside of the foot. Continue by proceeding medially around the ankle, crossing the Achilles tendon, and returning to the starting point.

Step 3: Apply stirrups starting on the medial aspect of the upper anchor, place posterior to the medial malleolus, ending on the upper anchor on the lateral side. Always apply stirrups with a medial to lateral pull, as 90% of ankle sprains are inversion (outside part of ankle) in nature. Apply horseshoe, beginning on the medial aspect of the mid-foot anchor and proceed behind the calcaneous and ending on the lateral aspect of the mid-foot anchor.

Step 8: Application of medial and lateral heel lock. Begin on the dorsum of the foot, as in the ﬁ gure eight. Move medially down the inside of the ankle over the plantar surface of the foot. Pulling up on the outside of the foot. Step 4: Apply second stirrup in a similar fashion. Overlap one-half to a one-third of the previous stirrup, it should lie directly over the malleoli. Apply second horseshoe in a similar fashion proceeding up, overlapping one-half to a one-third of the previous, crossing behind the ankle and over the Achilles tendon.

Step 9: Cross over front of ankle, crossing the medial malleolus, across the Achilles tendon, angling tape behind and below lateral malleolus. Angle tape underneath the foot and move back up to the dorsum of the foot.

Step 5: Apply third stirrup and horseshoe, repeating the above process. The third (3rd) stirrup should lie anterior to the medial malleolus.

Step 10: Continue across the lateral malleolus, across the Achilles tendon, angling tape behind and below the medial malleolus. Continue tape around plantar aspect of the foot, Step 6: Continue horseshoe strips until you have covered the ending on the dorsum of the foot. ankle to the upper anchor.

(Continued) Preventing ankle injuries 43

Box 4.2 Examples of various types of ankle braces

Ankle sleeves Captain Sports Adjustable Ankle Support with Silipos Malleolar Ankle Sleeve Spandex Wrap Provides mild compression to help reduce swelling in and Ankle sleeve with separate spandex wrap that provides around the ankle. Can be used to provide an additional additional support and stability to help prevent rolling of the protective layer to help prevent injuries. Two soft polymer gel ankle and limit joint stress. pads are molded into the elastic sleeve.

Banyan Healthcare Slip-on Ankle Compression Provides even compression for ankle support and helps DonJoy Stabilizing Ankle Brace reinforce strained muscles. Constructed of knitted elastic Non-stretching adjustable nylon ﬁ gure-eight straps which and soft material for added comfort. lock the calcaneus into place to help control abnormal eversion and inversion.

Non-rigid braces Swede-O lace-up ankle brace Provides good stability and can easily by retightened. Full elastic back ensures complete unrestricted blood ﬂ ow to the Achilles’ tendon. Internal U-shaped spiral stays Core Deluxe Canvas Lace-up Ankle Strapping Support provide extra support and further minimize the chance for ankle Shares a close resemblance with semi-rigid braces using injury. spandex wraps, but uses a lacing system. Offset eyelets and vinyl side supports help position the heel and stabilize the ankle. Can be easily retightened.

(Continued) 44 Chapter 4

Box 4.2 (Continued)

Semi-rigid braces Bauerfeind CaligaLoc Stabilizing Ankle Brace Stabilizes the entire ankle giving both medial and lateral support, and by counteracting supination. Heat moldable and can be reshaped if necessary for an individual customized ﬁ t.

Rehband - Active ankle Stable and easy to apply.

Aircast AirSport™ Ankle Brace Low profi le ankle brace specifi cally designed for professional athletes or chronic sufferers of ankle sprains. This support is beyond comparing to supports purchased over the counter because it is more often dispensed by orthopedic clinics or professional athletic trainers on the fi eld. The only ankle brace to have been proven effective in preventing injuries in large trials. Incorporates features, such as, semi-rigid shells and foam fi lled aircells to provide both support and comfort. Additional compression and stabilization are provided by an anterior talofi bular ligament cross-strap and by integrated forefoot and shin wraps.

Braces versus tape 3. Semi-rigid braces: The construction of these braces is similar to the non-rigid versions, Many studies have been completed comparing tap- but with the added feature of molded plastic ing versus bracing of the ankle to try and determine struts or air cushions. These are incorporated which is the better method. The general idea behind into the medial and lateral sides of the brace, braces and tape is that both measures prevent exces- similar in orientation to the stirrups used in sive plantar ﬂ exed inversion when needed. It is ankle taping. These braces are effective at known from previous research that in comparison stabilizing the ankle in inversion (rolling out) to tape, braces have the best mechanical capabilities and eversion (rolling in) but less effective when in terms of a reduction of ankle range of motion. the athlete is in a dorsiﬂ exed position (the most Although tape appears to have an equal restrict- common mechanism of ankle sprain), provide ing effect directly after application, the mechanical more stability and often are chosen during the support is already gone after short bouts of exer- rehabilitation and return to play phases of ankle cise. Braces do not show such loosening, and can injury. be easily tightened, even during the match. Given Preventing ankle injuries 45

Box 4.3 Basic proprioceptive program for the ankle (originally described by Tropp (1985))

Basic position Exercise The athlete stands on one (straight) leg while the other leg is The goal of the exercise is to attempt to make all balance lifted in the air with the knee bent at 90º. The arms are crossed correction using the ankle joint only, while using the arms, hips, in front of the chest. and knees as little as possible.

Program The program follows a “10–5–10” rule (i.e., 10 min, 5 times a week, for 10 weeks).

Level of diffi culty At fi rst balancing on the fl oor may represent an adequate challenge. Exercise diffi culty can be gradually increased during the program in the following order (1) perform exercises on a wobble board on a soft surface, (2) perform exercises on a wobble board on a hard surface, and (3) close the eyes.

Source: Originally described by Tropp (1985)

the etiology of ankle sprains, a forced plantar fl exed Balance training inversion of the foot exceeding the anatomical range of motion it can then be argued that braces One measure that has been studied extensively in are the best crash measure against ankle sprains. the recent years is improvement of neuromuscular However, the superior restricting effect of braces function, and more specifi cally balance board (pro- does not translate to a superior preventive effect. prioceptive) training. Trauma to mechanoreceptors Both tape and braces seem equally effective for the of the ankle ligaments after an ankle sprain can pro- prevention of recurrent ankle sprains. Both meas- duce a proprioceptive impairment in the ankle. This ures have the effect to prevent ankle sprain recur- might explain the increased risk of re-injury within rences and have less effect in “healthy” subjects, 1 year after an ankle sprain. Neuromuscular train- and in “healthy athletes” ankle sprains cannot be ing is designed for the rehabilitation after an ankle prevented using braces or tape. sprain and is thought to improve proprioception The preventive effect of these measures does not by re-establishing and strengthening the protec- result from a restriction in ankle range of motion tive refl exes of the ankle. Thereby, neuromuscular only. A common belief is that external ankles sup- training of the ankle is a potentially very effective ports prevent ankle sprains by affecting (or support- measure to reduce the risk of injury recurrences. ing) ankle proprioception instead of by restricting This potential effect has been shown in studies in a ankle inversion, or simply help guide the foot during variety of different sports, all showing an injury risk landing to avoid landing in a vulnerable, inverted reduction for players with previous ankle sprains position. This also explains the inability to help (Tropp et al., 1985; Verhagen et al., 2004b). players without previous ankle sprains, since healthy A basic proprioceptive training program is ankles have normal proprioception and do not have described in Box 4.3. Although such program is a tendency to land in an awkward foot position. effective in preventing ankle sprain recurrences, 46 Chapter 4

Box 4.4 Volleyball-speciﬁ c comprehensive balance training program developed by Verhagen et al. (2004b)

General information on the program Balance board The training program consists of 14 basic exercises on Exercise 5 and off the balance board, with variations on each exercise. One legged stance on the balance board with the knee fl exed. Exercises are divided into four subcategories: (1) exercises Maintain balance for 30 s and change stance leg. Repeat twice without any material; (2) exercises with a ball only; (3) exercises for both legs. with a balance board only; and (4) exercises with a ball and a Variations 1 2 3 4 balance board. The higher the exercise number the more diffi cult the exercise, where variations make the basic Exercise 6 exercises more challenging. One legged stance on the balance board with the hip and knee Exercises should not lead to physical complaints. Once an fl exed. Maintain balance for 30 s and change stance leg. Repeat athlete suffers pain in the ankle region after using this program, twice for both legs. reduce the number of exercise bouts and/or choose easier Variations 1 2 3 4 exercises. Exercise 10 How to use the program Step slowly over the balance board with one foot on the balance – During the execution of exercises the ankle may not be board. Maintain the balance board in a horizontal position while supported by brace or tape stepping over. Repeat 10 times for both legs. – Exercises should be incorporated in the usual warm-up routine, and during each warm-up one exercise should be Exercise 11 carried out lasting no more than 5 min. Stand with both feet on the balance board. Make 10 knee – Each week one exercise from each subcategory should be fl exions while maintaining balance. carried out, and once an exercise has been carried out the same exercise cannot be chosen again during that week. – During the season make exercises more challenging by Exercise 12 choosing higher exercise numbers and variations on basic One legged stance on the balance board with the knee fl exed. exercises. Make 10 knee fl exions while maintaining balance. Repeat twice for both legs.

Basic exercises No material Exercise 1 One legged stance with the knee ﬂ exed. Step-out on the other leg with the knee ﬂ exed and keep balance for 5 s. Repeat 10 times for both legs. Variations 1 2 3 4

Exercise 2 One legged stance with the hip and the knee ﬂ exed. Step-out on the other leg with the hip and knee ﬂ exed, and keep balance for 5 s. Repeat 10 times for both legs. Variations 1 2 3 4

Ball Exercise 3

Make pairs. Stand both in one legged stance with the knee fl exed. Keep a distance of 5 m. Throw and/or catch a ball 5 times while maintaining balance. Repeat 10 times for Ball and balance board both legs. Exercise 7 Variations 1 2 Make pairs. One stands with both feet on the balance board. Throw and/or catch a ball 10 times with one hand while Exercise 4 maintaining balance. Repeat twice for both players on the Make pairs. Stand both in one legged stance with the hip balance board. and knee fl exed. Keep a distance of 5 m. Throw and/or catch a ball 5 times while maintaining balance. Repeat Exercise 8 10 times for both legs. Make pairs. One stands in one legged stance with the knee Variations 1 2 fl exed on the balance board, the other has the same position on

(Continued) Preventing ankle injuries 47

Box 4.4 (Continued)

the fl oor. Throw and/or catch a ball 10 times with one hand while Exercise 14 maintaining balance. Repeat twice for both legs and for both Make pairs. One stands in one legged stance with the knee players on the balance board. fl exed on the balance board, the other has the same position Variations 1 2 on the fl oor. Play the ball with an upper hand technique 10 times while maintaining balance. Repeat twice for both Exercise 9 legs and for both players on the balance board. Make pairs. One stands in one legged stance with the hip Variations 5 6 7 8 and knee fl exed on the balance board, the other has the same position on the fl oor. Throw and/or catch a ball 10 times with one hand while maintaining balance. Repeat twice for both legs and for both players on the balance board. Variations 1 2

Exercise 13 Make pairs. One stands with both feet on the balance board. Play the ball with an upper hand technique 10 times while maintaining balance. Repeat twice for both legs and for both players on the balance board. Variations 5 6 7 8

Variations on basic exercises 1. The standing leg is stretched. 2. The standing leg is bent. 3. The standing is stretched and the yes are closed. 4. The standing leg is bent and the eyes are closed. 5. The standing leg is stretched and upper hand technique. 6. The standing leg is bent and upper hand technique. 7. The standing leg is stretched and lower hand technique. 8. The standing leg is bent and lower hand technique. an athlete’s motivation to comply with the pro- type of rehabilitation done, whether or not the gram may diminish during the 10-week time subject complied with the rehabilitation program, span. Additionally, this basic program consists and the quality of recovery that was achieved. of one static exercise, while most ankle sprains From this perspective, structured rehabilitation occur during dynamic situations. Thereby, based programs that include restoration of normal ankle on this basic proprioceptive program, more elab- motion, strengthening, and restoration of neu- orate dynamic, and sports-speciﬁ c programs may romuscular control and proprioception of the be developed to keep athletes motivated and to ankle complex should be advocated to all injured introduce dynamic exercises. As an example, Box 4.4 athletes. Until function is completely normal, ath- shows a more elaborate volleyball-speciﬁ c proprio- letes should be urged to make use of either a tape ceptive program which has been proven effective or a brace. in a large trial (Verhagen et al., 2004b). Similar programs may be developed for other sports. References Take-home message Bahr, R., Lian, O., Bahr, I.A. (1997) A twofold reduction Preventive measures should be advocated to all ath- in the incidence of acute ankle sprains in volleyball letes, especially the subgroup with a history of previ- after the introduction of an injury prevention ous sprains or instability episodes. In this subgroup, program: a prospective cohort study. Scandinavian subsequent re-injury risk is highly dependent on the Journal of Medicine and Science in Sports 7, 172–177. 48 Chapter 4 de Noronha, M., Refshauge, K.M., Herbert, R.D., subjects: a prospective study. American Journal of Sports Kilbreath, S.L., Hertel, J. (2006) Do voluntary strength, Medicine 33, 415–423. proprioception, range of motion, or postural sway Verhagen, E., van der Beek, A., Bouter, L., Bahr, R., van predict occurrence of lateral ankle sprain? British Mechelen, W. (2004a) A one season prospective cohort Journal of Sports Medicine 40, 824–828. study of volleyball injuries. British Journal of Sports Hertel, J. (2000) Functional instability following lateral Medicine 38, 477–481. ankle sprain. Sports Medicine 29, 361–371. Verhagen, E., van der Beek, A.J., Twisk, J.W.R., Bahr, R., Kofotolis, N.D., Kellis, E., Vlachopoulos, S.P. (2007) Bouter, L.M., Van Mechelen, W. (2004b). The effect Ankle sprain injuries and risk factors in amateur soccer of a proprioceptive balance board training program players during a 2-year period. American Journal of for the prevention of ankle sprains, a prospective Sports Medicine 35, 458–466. controlled trial. American Journal of Sports Medicine 32, Morrison, K.E., Kaminski, T.W. (2007) Foot characteristics 1385–1393. in association with inversion ankle injury. Journal of Athletic Training 42, 135–142. Quinn, K., Parker, P., de Bie, R., Rowe, B., Handoll, H. (2000) Interventions for preventing ankle ligament Further reading injuries. Cochrane Database of Systematic Reviews (Online) 2, CD000018. Tik-Pui Fong, D., Hong, Y., Chan, L., Shu-Hang Yung, P., Bahr, R. (2004a) Acute ankle injuries. In R. Bahr & Chan, K. (2007) A systematic review on ankle injury S. Maehlum (eds) Clinical Guide to Sports Injuries, pp. and ankle sprain in sports. Sports Medicine 37, 73–94. 393–407. Human Kinetics, Champaign. Tropp, H., Askling, C., Gillquist, J. (1985). Prevention of Bahr, R. (2004b) Pain in the ankle region. In R. Bahr & S. ankle sprains. American Journal of Sports Medicine 13, Maehlum (eds) Clinical Guide to Sports Injuries, 259–262. pp. 408–418. Human Kinetics, Champaign. Willems, T.M., Witvrouw, E., Delbaere, K., Philippaerts, R., Bahr, R. (2007) Can we prevent ankle sprains? In De Bourdeaudhuij, I., De Clercq, D. (2005a) Intrinsic D. MacAuley & T. Best (eds) Evidence-Based Sports risk factors for inversion ankle sprains in females—a Medicine. Blackwell BMJ Books, London. prospective study Scandinavian Journal of Medicine and Hansen, K.J., Bahr, R. (2004) Rehabilitation of ankle Science in Sports 15, 336–345. injuries. In R. Bahr & S. Maehlum (eds) Clinical Guide Willems, T.M., Witvrouw, E., Delbaere, K., Mahieu, N., to Sports Injuries, pp. 419–422. Human Kinetics, De Bourdeaudhuij, I., De Clercq, D. (2005b) Intrinsic Champaign. risk factors for inversion ankle sprains in male Chapter 5 Preventing knee injuries Timothy E. Hewett1, Bruce D. Beynnon2, Tron Krosshaug3 and Grethe Myklebust3

1Cincinnati Children’s Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA 2Department of Orthopaedics and Rehabilitation, McClure Musculoskeletal Research Center, The University of Vermont, VT, USA 3Oslo Sports Trauma Research Center, Norwegian School of Sport Sciences, Oslo, Norway

from an opponent. The inciting moment of the Epidemiology of knee injuries in sports injury often surprises the players since they are performing movements that they have done many This chapter will not focus on the prevention of times in the past. knee injuries in general. Instead, it will review the Among the Olympic winter sports, ACL injuries epidemiology of one of the most serious knee inju- are most the common in the sport of alpine ski- ries experienced during participation in Olympic ing. Alpine ski injuries are typically reported as Sports; disruption of the anterior cruciate liga- the number of ACL injuries per 100,000 skier days ment (ACL). This injury is not the most common (Table 5.1) and, therefore, a comparison of these ligament injury experienced in sports. However, data with that from other sports cannot be made as described below it is one of the most serious in in a direct manner. The injury often occurs during terms of absence from sport, pain, disability, and an high speed situations with considerable magnitudes increased risk of development of osteoarthritis about of forces and torques produced across the ath- the knee joint. In Olympic summer sports, the high- lete’s knee. The new Olympic sport of snowboard- est ACL injury incidences occur during participation ing includes the different disciplines of “big air,” in basketball, soccer, and team handball. The highest “snowboard cross,” “half pipe,” and “slalom.” Most injury risk is among top level female athletes who consider these sports to be associated with high compete in team handball and soccer (Table 5.1). numbers of knee injuries; however, precise injury A gender difference is very apparent in ball data are currently not available. This is a sport that sports, where female athletes suffer ACL injuries is under development and therefore we must fol- 4–6 times more often than their male counterparts low it closely and carry out prospective studies to taking part in the same sports at the same level of record the incidence rates of knee and ACL injuries. competition (Table 5.1). The injury mechanism is There is no consistent data regarding sex differ- frequently the “non-contact” type which means ences in recreational alpine skiers; however, female that there is limited contact between the opponent competitive alpine skiers have twice the incidence and the athlete about the lower extremity immedi- rate of ACL injuries in comparison to male compet- ately before and during the injury. In many situa- itive alpine ski racers. In the sport of ice hockey the tions, athletes are perturbed just before the injury incidence of ACL injuries is low; however, a greater occurs, and the injury is often incited by a push number of medial collateral ligament (MCL) injuries are seen as a result of a direct blow to the lateral aspects of the knee by an opponent. MCL Sports Injury Prevention, 1st edition. Edited by R. Bahr and injuries are also common in soccer, often with the L. Engebretsen Published 2009 by Blackwell Publishing ISBN: 9781405162449 same injury mechanism as in ice hockey.

49 50 Chapter 5

Table 5.1 Risk of ACL injury in different sports. The numbers reported are average estimates based on the studies available.

Sport Competition Training Rank2 Comments incidence1 incidence1

Team sports Basketball 0.28-0.40 *0.14 15-17 NBA & WNBA 0.08-0.16* *0.04 *NCAA data 2006 Soccer 0.33-2.2 *0.10 15-Sep *NCAA data 2006 0.12 *0.04 Team handball 1.3-2.8 0.03 10-Aug Elite level 0.23 Volleyball 0.19 0.05 NA NCAA data 2006 Field hockey 0.15 0.05 NA NCAA data 2006 Ice hockey 0.14 NA NCAA data 2006 0.21 0.02 Individual sports Alpine skiing 4.4 ** NA twice of in some studies 4.0 ** Gymnastics 0.33 * 15-Dec Wrestling 0.70 0.06 NA NCAA data 2006

1Incidence is reported for adult, competitive athletes as the number of injuries per 1000 hours of training and competition (*per 1000 athletic exposures) or **per 100,000 skiing days in alpine skiing. 2Rank indicated the relative rank of ACL injuries within the sport in question. NA: Not available.

The incidence of ACL injuries appears to be sig- unusual. Studies have shown that the long-term nifi cantly greater during competition than during risk of suffering premature osteoarthritis is con- training (Table 5.1), and this fi nding is consistent siderably greater among ACL injured athletes in in sports. Studies of European team handball ath- comparison with athletes who do not suffer these letes have shown that the relative risk of sustaining severe injuries. This results in substantial direct an ACL injury is approximately 30 times greater and indirect treatment costs in relation to medical during competition than during training. This dif- disability. Osteoarthritis occurs, at a rate that is 10 ference is expected, since the intensity and corre- times greater, for athletes who suffer an ACL injury sponding loads transmitted to the knee and ACL regardless of whether they choose reconstructive are higher during competition when compared to surgery or non-operative treatment. The cost of training sessions. In most sports, training sessions this injury is estimated to be 17,000 dollars includ- include warm-up exercises and technical drills, ing surgical and rehabilitation costs, and these which are associated with a lower risk of injury. costs can be considerably higher over the athlete’s ACL injury has received great attention even life span with a long-term disability, sick leave, and though it is not the most frequent injury suf- the possibility of additional surgical procedures. fered during participation in sports. The primary reason for this is the severity of the injury: For most athletes involved with Olympic sports, sur- Key risk factors: how to identify gery is necessary to return them to their sport at athletes at risk the same level of competition they were capable of prior to injury and rehabilitation and recovery requires a long absence from sport. A recovery A large number of studies have investigated the time that ranges between 6 and 12 months is not potential risk factors for severe knee injuries and a Preventing knee injuries 51 majority of this work has focused on ACL injuries. Internal risk factors: previous knee However, there remains a signifi cant knowledge injury gap concerning the risk factors for serious knee Recent studies have suggested that having a pre- injuries such as an ACL disruption. This is because vious injury may be a risk factor for subsequent only a few well-designed prospective studies are injury—either a rupture of the ACL graft, an ACL available and most studies have assessed only one rupture to the contralateral knee, or another type factor in isolation. Considering that the risk fac- of acute or overuse knee injury. One study also tors for ACL injury are multifactorial (e.g., mul- showed that females experience ACL re-rupture at tiple risk factors act in combination to increase a rate twice that of men. an athlete’s risk of suffering an ACL injury), this approach is not appropriate to assess how risk factors act in combination to increase an individu- Age al’s risk of suffering a severe knee ligament injury. Further, the majority of these studies have identi- Although there appears to be a consensus that the fi ed sex differences in anatomy as well as hormo- risk of suffering an ACL injury increases for female nal and neuromuscular function; however, they athletes during their growth spurt, there are no fail to relate these differences to the risk of suffer- investigations that have included age as a potential ing a severe knee ligament injury (Table 5.2). risk factor in analysis of serious knee injuries in skeletally mature athletes. Similarly, no investigations of the effect of age on the likelihood of suffering a External risk factors: shoe–surface knee injury in skeletally immature athletes exist. interaction

The shoe–surface interaction has been studied Body composition as an ACL injury risk factor in different sports. A study of Australian football athletes has reported An increased body mass index (BMI) has been that the risk of sustaining non-contact ACL inju- found to be associated with an increased risk of ries increased during high-evaporation and low- suffering ACL injuries in female cadets attending rainfall periods. Studies of soccer athletes reported the US Military academy. However, other studies that competing on artifi cial turf does not increase have not found such a relationship. The data on the risk of knee injuries compared with natural BMI appear to be inconsistent, making it diffi cult grass. In contrast, recent studies of professional to establish reliable conclusions. American football athletes suggest that the incidence of ACL injuries may be greater on the new Familial tendency and ethnicity artifi cial turf designs in comparison with the older turf designs. In the sport of European team hand- Two case-control studies reported that familial ten- ball, it was shown that the risk of ACL injury was dency is a risk factor for ACL injury. Athletes who 2.4 times greater when competing on artifi cial suffer an ACL tear are twice as likely to have a rela- fl oors (with an increased coeffi cient of friction) tive with an ACL tear compared with age, sex, and compared with wooden fl oors. Earlier studies sport-matched controls. of American football athletes have shown that In a recent 4-year cohort study, it was found the use of longer cleat lengths and an associated that white European American athletes were 6.6 higher torsional resistance at the foot–turf inter- times more likely to suffer an ACL tear compared face places these athletes at an increased risk of with other ethnic groups. suffering knee injuries. There is little doubt that the shoe–playing surface interface is important Anatomical factors to consider when developing intervention strategies to reduce the incidence rate of serious knee The Q-angle of the knee (Figure 5.1) has been studied injuries. as a possible explanation for the gender difference 52 Chapter 5

Table 5.2 Internal and external factors for knee ligament sprains in different sports. The numbers reported are average estimates based on the studies available.

Risk factor Relative risk1 Evidence2 Comments

External risk factors Surface 2–2.4ϫ* ϩ Few studies. Greater risk of injury when competing on artifi cial fl oors relative to natural wood fl oors, but only for women. Meteorological 1.9–2.8ϫϩ Only one study. Non-contact ACL injuries more frequent during high conditions evaporation and low-rainfall periods. Footwear NA ϩ Only two studies. Shoes with longer cleats produced signifi cantly greater ACL injury rates. Game versus 29.9ϫϩ (ϩ) Higher ACL injury rate during competition. practice Internal risk factors Gender 2–8ϫϩϩRisk of ACL injury is greater in women compared to men when participating in the same sport at the same level of competition. Previous injury 3.1–11.3ϫϩ Risk for new knee injuries in general as well as new ACL injuries, both in the reconstructed and the contralateral knee. Age NA 0 No studies were found that included age as a potential risk factor for ACL injury. BMI 3.5ϫϩFew studies. Higher risk of ACL injury for women with high BMI. Confl icting results. Familial 2.0ϫ* ϩ Only two studies. Athletes with an ACL tear are two times more likely to have a tendency relative with an ACL tear. Race 6.6ϫ* ϩ Only one study. White European American players more susceptible to ACL tears compared with other ethnic groups. Q-angle NA ϩ Higher Q-angle in females. Confl icting results. Leg length NA ϩ Long femur relative to tibia may be a risk factor in skiers. Wide pelvis relative to femur predicts dynamic valgus in one-legged squats. Intercondylar 3.7–6.0ϫϩ Small notch width index may lead to increased risk of suffering an ACL injury. notch width index Several positive studies, but also some studies with confl icting results. (Ligament NA 0 No risk factor studies. Relative larger cross-sectional area in males after cross-sectional area) adjusting for body weight. (Ligament material NA 0 No risk factor studies. Female ligaments have lower strain and strain energy properties) density at failure, as well as lower modulus of elasticity compared to males. Anterior knee 2.7ϫϩOnly two studies. The larger, prospective study found a 2.7-fold increased risk laxity for ACL injury in females with A-P knee laxity values greater than 1 SD of the mean. A-P knee laxity had no effect on risk of ACL injury in males. General joint laxity 2.8ϫϩFew studies. Females exhibit greater joint laxity than males. Skiers with increased hyperextension of the knee are in signifi cantly increased risk of suffering ACL injury. Patella tendon- NA 0 No risk factor studies. PTTSA is greater in females compared to males. tibia shaft angle (PTTSA) Foot pronation/ NA ϩ Three studies found a relationship, whereas one study found no relationship. navicular drop Phase of 3.2 ϫ* ϩ Studies that have accurately measured phase of cycle with serum- or urine- menstrual cycle based assays of estradiol and progesterone have observed a greater proportion of ACL injuries in the pre-ovulatory phase of the menstrual cycle in comparison with the post-ovulatory phase. One study of recreational alpine skiers found the odds ratio of suffering an ACL disruption was 3.2 times greater during the pre-ovulatory phase compared to the post-ovulatory phase of the menstrual cycle in recreational alpine skiers. Knee fl exion NA 0 Only one risk factor study that showed no relationship. Confl icting results during landing among studies looking at gender differences. Valgus motion and NA ϩ Only one risk factor study. Valgus moments have a sensitivity of 78% and a valgus moment specifi city of 73% for predicting ACL injury status. during landing

(Continued) Preventing knee injuries 53

Table 5.2 (Continued)

Risk factor Relative risk1 Evidence2 Comments

Leg dominance NA 0 Only one risk factor study, but no signiﬁ cant effect of this variable on ACL injury during landing risk. Females have greater side-to-side (leg dominance) differences in knee loads. Quadriceps NA 0 No risk factor studies. Females exhibit greater quadriceps dominance than dominance males. Muscle stiffness NA 0 No risk factor studies. Females have lower muscle stiffness than males. Muscle strength NA 0 No risk factor studies. Females have lower muscle strength than males. Muscle reaction time NA 0 No risk factor studies. Time to peak force NA 0 No risk factor studies. Fatigue NA 0 No risk factor studies. No gender differences. Fatigue may alter the neuromuscular control of knee biomechanics.

ASIS

Q-angle

Figure 5.2. A narrow intercondylar notch width has been proposed as a risk factor for ACL injuries

Mid-patellae signifi cantly larger than the mean Q-angles for Tibial tubercle athletes who were not injured (14º versus 10º). In contrast, others have reported that the risk of suf- Figure 5.1. The Q-angle is formed in the frontal plane by fering a knee injury was not related to anatomical two lines: (1) the line between the tibial tubercle to the alignment differences such as Q-angles. One study middle of the patella and (2) the line from the middle of the patella to the anterior superior iliac spine reported that pelvic width to thigh length ratio, and not Q-angle, predicts dynamic valgus angulation of the knee during the single leg squat. It has also been in ACL injury rates, with the rationale that high shown that a long thigh to shank ratio may be a risk Q-angles may be associated with an excessive val- factor for ACL injuries in competitive alpine skiers. gus loading of the knee. These studies consist- One of the most studied factors in relation to ently report higher Q-angles in females. In a recent ACL injury is the femoral intercondylar notch case-control study, it was reported that the mean width (Figure 5.2). Several investigators have Q-angles of athletes sustaining knee injuries were hypothesized that a narrow intercondylar notch 54 Chapter 5 or notch width index (e.g., the ratio of the width and such factors can only explain a relatively of the femoral notch to the width of femoral con- small proportion of the variance in ACL injury dyles when observed through X-ray in a coro- risk. Generalized joint and ligament laxity have nal plane view) may predispose athletes to an also been proposed as risk factors for knee liga- increased risk of ACL injury. One cause could be ment injuries; however, most of these studies have that a narrower femoral notch is associated with evaluated the effect of these variables on all lower a smaller, weaker ACL. This hypothesis has been extremity injuries as a group and not knee liga- challenged by recent studies that used MRI to cor- ment injuries in isolation. A few exceptions exist relate the size of the ACL with the size of the inter- and these studies suggest that increased general- condylar notch. These studies suggest that the size ized joint laxity and increased hyperextension of of the ACL cannot be predicted by the size of the the knee may be associated with increased risk of femoral intercondylar notch. Another possibility suffering an ACL injury. is that impingement of the ACL against the femoral intercondylar notch may be more predominant Foot pronation when the notch is narrow and this may induce microtears of the ligament during participation It has been suggested that foot pronation may lead in athletics that subsequently progress to mac- to anterior tibial translation, and subsequently rotears that weaken the ligament and predispose strain the ACL; however, the results are confl ict- it to an increased risk of a complete tear. Research ing. Three case-control studies found a relationship is needed to delineate the role of notch impinge- between foot pronation/navicular drop and ACL ment as an ACL injury risk factor. Three prospec- injuries whereas one found no such relationship. tive cohort studies, as well as several other lesser quality studies, have found that athletes with a Hormonal factors decreased femoral notch width are at an increased risk of suffering an ACL injury. There are, however, To determine how different phases of the men- several studies that do not show such an associa- strual cycle affect ACL injury risk, it appears nec- tion and as a consequence it remains unclear how essary to accurately describe the hormone milieu notch width geometry, or notch width index, is with serum- or urine-based measures of hormone related to increased risk of suffering an ACL injury. concentrations and then use these data to accurately identify the phase of the cycle when injury Ligament material properties and occurs. The use of an athlete’s self-report of men- joint laxity strual history is inadequate to determine the phase of cycle at the time of injury. Review of studies The size and material properties of the ACL are that have used serum- and urine-based measures factors that may infl uence the risk of this ligament of hormone concentrations reveal that the risk of tearing. It has been shown that ACLs in females suffering a non-contact ACL injury can be three- are smaller than in males when normalized for fold greater during the pre-ovulatory phase of body weight. In addition, it has been reported the menstrual cycle in comparison to the that female ligaments have lower strain and strain post-ovulatory phase. energy density at failure as well as 22.5% lower modulus of elasticity. However, at the curren Patella tendon-tibia shaft angle and point in time, no risk factor studies have consid- tibial plateau slope ered these variables. On the other hand, there are studies that have established increased anterior One of the most investigated hypotheses in recent knee laxity as a risk factor for females, and this years is whether a quadriceps contraction per- may be a result of differences in the size and mate- formed with the knee near extension can create a rial properties of the ACL. It is important for us force of suffi cient magnitude on the patellar ten- to point out that these studies are relatively small don such that it produces an anterior translation Preventing knee injuries 55 of the tibia relative to the femur and ruptures on how movement patterns can contribute to ACL the ACL (see also description of Injury mecha- injuries, see section on Injury mechanisms later. nisms later for further explanation). The patella tendon-tibia shaft angle (PTTSA) is the sagittal Other neuromuscular measures plane angle between the tibia (ankle to knee joint) and the line of action of the patellar tendon. Several neuromuscular measures have been pro- When the knee is near extension, an increased posed as possible risk factors for ACL injury. PTTSA produces a larger magnitude of anterior- Quadriceps dominance, muscle reaction time, directed force on the tibia and increases the loads time to peak force, muscle stiffness, and muscle transmitted to the ACL. It has been showed that strength and fatigue are all factors that may have females have greater PTTSA throughout the range an infl uence on an athlete’s risk of suffering an of knee fl exion compared to males, and that this ACL injury. It has been shown that females exhibit angle is greater when the knee is close to full knee greater quadriceps dominance and that they have extension. However, no risk factor studies have less muscle stiffness and muscle strength compared included PTTSA in the analyses. The same is true to males. However, none of these factors have for the slope of the tibial plateau in the sagittal been studied as ACL injury risk factors and conse- plane. An increased slope of the plateau will gen- quently it is not possible to determine the relative erate an increased anterior-directed force on the importance of these factors at this point in time. tibia when compression forces, such as that produced during landing or plant and cut maneuvers, Take-home message are produced across the knee. It appears that the risk factors for serious knee liga- Movement patterns ment injuries are likely multifactorial in nature. It has been shown that the combination of risk fac- Another explanation for the gender difference in tors such as a small femoral notch width and large ACL injury rate is that females may perform a cer- body mass results in a dramatic increase in the risk tain movement different from males. Landing with of ACL injury (relative risk 26.2) compared to hav- straighter knees implies higher PTTSA and thereby ing only one of the two factors in isolation (rela- an increased anterior-directed shear force compo- tive risks of 3.5 and 4.0, respectively). However, as nent on the tibia. Although several studies have is apparent from this chapter, our current knowl- investigated if females land with straighter knees edge on the many potential risk factors for serious compared with males, there is no consensus in knee injuries is limited. the literature. Furthermore, in a recent prospective Perhaps, the most important from the athlete’s risk factor study of 205 female athletes who par- point of view is the fi nding that a suboptimal ticipated in soccer, basketball, or volleyball, where movement pattern will increase the risk of such knee fl exion angles produced during jump land- injuries. This fi nding also agrees well with numer- ings were assessed, no signifi cant differences were ous studies that have shown benefi cial effects of found between injured and un-injured subjects. neuromuscular training programs focusing on The same study showed that the valgus motion strength, balance, and maintaining the “knee- and valgus moments that were produced when over-toe” position during dynamic movements. landing from a jump predicted ACL injuries with Drop-jumps and one-legged squats are simple a sensitivity of 78% and a specifi city of 73%. Also, tests that can be used to screen athletes with poor leg dominance was studied, but this factor was not strength, balance, and “knee-over-toe” control. found to be associated with risk of suffering an Furthermore, one should avoid excessive shoe– ACL injury. It should be mentioned that only nine fl oor friction by making sure to wear shoes that ACL injuries were included in this study, so the “fi t” the playing surface. results should be interpreted with caution until It should be noted that other factors such as ana- confi rmed in other studies. For more information tomic alignment and ligament properties are not 56 Chapter 5 easily modifi able, and therefore, direct interven- injured when it is in a position of greater fl exion. tion on such factors may be diffi cult. Nevertheless, Although the majority of ACL injuries that occur if we can identify individuals at increased risk in Olympic sports are non-contact by defi nition, (e.g., athletes that are at increased risk of suffering the movement patterns often involve perturba- ACL injury based on poor anatomic alignment), it tion by an opponent (e.g., body contact before the may be possible to initiate individualized injury injury). However, even if a few details are known, prevention measures on these individuals and we still lack vital knowledge about the injury reduce their risk of injury by enhancing their neu- mechanisms. A complete biomechanical descrip- romuscular control. tion should quantify entire body and knee kinematics, loading directions and magnitudes, and the rate of application of external and internal forces about the lower extremity. Injury mechanisms Knee ligament injury mechanisms in A simple description of non-contact alpine skiing ACL injury situations in ball/team sports Knee ligament injury mechanisms that occur during traditional alpine skiing have been inves- During most Olympic sports, ACL injuries are com- tigated for some time, and various injury mecha- monly non-contact in nature and can occur during nisms have been proposed, both for ACL injuries plant and cut maneuvers (Figure 5.3), but a high and other ligament injuries. Some knee injury proportion of these injuries also occur during land- mechanisms are equipment related, such as when ings (Figure 5.4). In basketball, landings are the most the back portion of the ski boot acts to produce frequently reported mechanism for ACL injuries. a “boot-induced anterior drawer” (e.g., an anterior It is important to realize that while an ath- directed force on the tibia that tears the ACL), or lete may appear to land on both feet with body when the edge of the ski is caught in the snow. weight equally distributed between legs, at the Some injury mechanisms are associated with point of impact the entire ground reaction force certain circumstances, such as a backward fall, may be supported by the leg that suffers an injury. with the weight of the skier on the inner edge of Previous studies have suggested that the knee the tail of the ski resulting in a sharp uncontrolled is near extension at the time of ligament injury inward twist of the lower leg (Figure 5.5). This sce- (i.e., less than 30º); however, recent studies that nario is termed as the “phantom foot mechanism” have used more sophisticated video analysis with and is considered the most common ACL injury multiple camera angles indicate that the knee is mechanism in alpine skiing.

Figure 5.3. Frame sequence of a plant and cut ACL injury showing the team handball athlete (a) at initial ground contact, (b) at 40 ms, and (c) at 100 ms, respectively. Reproduced with permission from the Scandinavian Journal of Medicine and Science in (a) (b) (c) Sports Preventing knee injuries 57

(a)

(b)

(c)

Figure 5.4. Landing injury in basketball. The injured player is seen in white shorts in the middle of the images (a) at initial ground contact, (b) 33 ms after initial contact, corresponding to the approximate estimated time of rupture, and (c) 133 ms after initial contact. Reproduced with permission from the American Journal of Sports Medicine

However, previous studies on knee ligament captured on video. These approaches have meth- injury mechanisms produced during alpine ski- odological limitations, and there is a need for the ing have mainly used approaches such as athlete improvement of the existing injury mechanism interview and visual inspection of injuries descriptions. 58 Chapter 5

Figure 5.5. Drawing of the body position in the “phantom foot” injury mechanism. The weight of the skier is on the inner edge of the tail of the ski resulting in a sharp uncontrolled inward twist of the lower leg. Copyright: ACL awareness training— Phase II, Vermont Safety Research, 1994. Illustration is copyrighted by William Hamilton, 1988 and is adapted with permission

Non-contact ACL injury mechanisms in against the medial aspect of the lateral femoral con- ball/team sports: different hypotheses dyle and strains the ACL, there is evidence that valgus loading of the tibia relative to the femur is an Although gross biomechanical information about important aspect of the loads applied to the knee serious knee injuries exists, detailed biomechani- during an ACL injury. A recent prospective risk fac- cal information (i.e., joint loading) is not known. tor study showed that increased valgus loading when For injuries that are caused by a direct blow to the landing from a jump was associated with increased knee, which is the case for many MCL injuries, the risk of suffering an ACL injury amongst soccer, bas- loading patterns are more obvious. However, for ketball, and volleyball athletes. Several studies also non-contact ACL injuries, different hypotheses are report that MCL injuries are frequently seen in com- heavily debated in the scientiﬁ c community. bination with non-contact ACL injuries, indicating that valgus loading was present. Interestingly, Valgus loading laboratory-based motion analysis studies have demonstrated that females develop larger magnitudes of Studies have shown that external tibial rotation valgus and external torques about the knee when combined with valgus rotation with the knee in landing from a jump in comparison to males, sug- an extended or partially ﬂ exed position initiates gesting that knee valgus loading may explain, at ACL strain, as the ligament contacts and then least in part, the larger incidence rate of ACL inju- impinges against the medial aspect of the lateral ries seen in females compared to males taking part femoral condyle (Figure 5.6). in the same sport at the same level of competition. The ligament impingement theory has also been A recent video-based analysis study of actual ACL suggested in video analysis studies. Although it injury situations reported a large number of val- remains unknown how the ligament impinges gus collapses about the knee for female athletes. Preventing knee injuries 59

vigorous quadriceps contraction when landing on an extended knee can produce high ACL strain values. Axis In this theory, contraction of the quadriceps muscle group and subsequent engagement of the patel- lofemoral joint produces a load on the patella tendon which has an anterior-directed angulation relative to the tibia when the knee is near exten- Femu sion, and this generates an anterior-directed force component on the tibia. As the knee is moved from an extended to a fl exed position, the orientation of Meniscus the patellar tendon relative to the tibia moves from an anterior to a posterior direction as does the corresponding direction of the force produced by the quadriceps extensor mechanism. Understanding this biomechanical relationship, studies have investigated if the gender difference in ACL injury incidence can be explained by the fact that females appear to land with their knee and hip in a more extended position. Anterior cruciate The fi ndings from these studies confl ict. In actual ligament injury situations, females are found to be at signifi - cantly greater knee and hip fl exion angles at initial contact with the playing surface and at the assumed point of injury in comparison to males. This fi nding suggests that landing on straighter knees may not be an important explanation for the observed difference in ACL injury incidence rates between males and females. Although a novel cadaver study

Figure 5.6. A sidestep cutting maneuver may lead to demonstrated that the quadriceps-induced anterior valgus and external tibial rotation. The solid arrow drawer mechanism is capable of producing ACL rup- indicates a possible impingement of the ACL against the ture, this approach was criticized for not including intercondylar notch. Reproduced with permission from ground reaction forces, which may act posteriorly Gazette Bok on the tibia and help restrain anterior translation of the tibia. Three mathematical model simulation This evidence suggests that valgus loading plays an studies of landing and plant and cut maneuvers, important role in many of the non-contact ACL which included the effect of ground reaction and injury situations, at least amongst female athletes. hamstrings forces, all concluded that the anterior- However, there are likely to be other forces and tor- directed shear force that acts on the tibia cannot ques applied to the knee during injury, since it has generate suffi cient magnitude to rupture the ACL, been shown that pure valgus loading will rupture even in extreme cases where hamstrings forces are the MCL fi rst, then the ACL secondly—only a lim- non-existent. Still, the results of these studies were ited number of MCL ruptures are found in conjunc- quite different, possibly due to the fact that realistic tion with non-contact injury of ACL injuries. modeling and simulation of the knee joint is challenging. In contrast to the fi ndings from mathemati- Quadriceps-induced anterior tibial cal modeling studies, a recently published cadaver drawer study demonstrated that anterior tibial translation Several cadaver studies have shown that quad- and ACL strain proportional to the applied quadri- riceps loading strains the ACL when the knee is ceps force were generated when the ground contact near extension. It has been hypothesized that a forces were also included. However, since the loading 60 Chapter 5 was far from injury levels, it is not possible to make Olympic Games, it is important to allow an ade- fi rm conclusions regarding the quadriceps-induced quate number of days for the athlete to recover. anterior drawer mechanism from this study. Further For young athletes who participate in sports at a investigations are required to delineate the role of high level, there is a clear tendency for participa- quadriceps-induced anterior drawer loading of the tion on many teams and to compete at different tibia in producing ACL injuries. age levels. This increases the number of matches/ competition and reduces the time they have, Internal tibial rotation available for rest and training. Every sports federation should be aware of this and try to protect the There are several factors that suggest internal rota- young athletes from over participation in sports. tion of the tibia relative to the femur on a relatively Another aspect that must be considered for piv- extended knee could be a potential mechanism of oting sports that are performed on courts and turf non-contact ACL injuries. First, cadaver and human is the friction between the fl oor and the shoes. studies have shown that the ACL is strained when Playing surfaces with a low coeffi cient of friction torques are applied to internally rotate the tibia rel- can prevent ACL injuries. Athletic shoes should ative to the femur. Second, internal rotation is fre- be designed to provide suffi cient friction and quently reported to be the mechanism of injury in mechanical interlock with the playing surface to athlete interview studies, in video analysis, as well allow optimal performance, not making pivoting as suggested from the associated clinical fi ndings. diffi cult, yet not producing injury. Athletes who Motion analysis studies of sidestep cutting maneu- take part in sports that are performed on surfaces vers usually show a dominance of internal tibial with different friction levels should consider the rotation during the stance phase. However, males use of different types of shoes. For example, one are reported to exhibit this pattern to a larger degree for high- and another for low-friction playing than females indicating that other loading scenarios surfaces. This is an important factor in relation are likely to be associated with many female non- to prevent an ACL injury. We must also keep in contact ACL injuries. Hyperextension has also been mind that proper cleaning and maintenance of the proposed as a possible mechanism, but this seems playing surfaces infl uences the friction at the shoe– unlikely considering that such injuries have not surface interface for both indoor fl oors and turfs. been reported in any video analysis studies. In relation to ACL injuries among the different skiing disciplines, there are several risk situ- Take-home message ations that are important. Among alpine skiers, it is extremely important that the athletes use Currently, little is known about the specifi c knee equipment and bindings adjusted by trained and loads that cause non-contact ACL injuries. What certifi ed technicians. Alpine resorts must take pre- seems clear is that valgus loading is an important cautions to prevent over-crowding in an effort to factor in many cases; implying that avoiding val- avoid collisions, and obstacles must be suffi ciently gus knee motion (or “kissing knees”) is important. padded and marked. Snowboard facilities should be properly maintained and appropriate construction of the half- Identifying risks in the training and pipe and jumps are important to reduce the risk of competition program suffering injury.

The risk of suffering a serious knee injury may Preventive measures increase during championships or playoff situations, when the best players are exposed to an abnormally high number of matches during a Neuromuscular training appears to be effective at short-time period. In planning championships and reducing ACL injury risk, particularly for female Preventing knee injuries 61 athletes in sports performed on courts and turf. For Safety equipment the optimal design of ACL intervention programs, Two investigations have studied the effect of pro- we can learn much from a systematic analysis of phylactic knee bracing on American football ath- the common components of the published inter- letes (Sitler et al., 1990; Albright et al., 1994). The ventions, successful and unsuccessful, designed to fi rst study found signifi cantly fewer MCL inju- reduce ACL injury risk in athletes. Analyzing the ries occurred in athletes who used prophylactic common components of the most effective and least bracing in comparison to those who did not use effective programs is useful for the development braces; however, the effect of prophylactic bracing of effective intervention protocols. Hewett et al., on ACL injures could not be determined because (2006a) performed a systematic review of interven- of the small sample size (Sitler et al., 1990). In con- tion studies designed to reduce ACL injury risk in trast, the second study did not fi nd statistically sig- female athletes and revealed that several programs nifi cant differences between braced and unbraced appear to reduce ACL injury risk. In contrast, other athletes in terms of the risk of sustaining MCL studies have failed to show an effect of neuromus- injuries (Albright et al., 1994). Additional research cular training on the reduction of ACL injury rates is needed in this area to establish the effect that or establish that they can alter lower extremity bio- prophylactic braces have on knee injuries. mechanics. Most of what is known has come from Although alpine ski bindings have been devel- studies of female athletes, as they are at increased oped to effectively protect skiers from tibia and risk of ACL injury. As described earlier, the mecha- ankle fractures, the present day alpine ski bind- nism of ACL injury may differ between females and ing designs are inadequate for preventing ACL males, particularly with respect to the dynamic posi- disruptions, even when the bindings function as tioning and control of the knee, as females demon- designed and are properly adjusted. In a large pro- strate greater valgus collapse of the lower extremity, spective study of ACL-defi cient professional alpine primarily in the coronal plane. However, female skiers, the risk of sustaining a subsequent knee athletes may serve as a working model for any ath- injury (e.g., injury to other structures about the lete at increased risk of suffering an ACL injury. In knee such as articular cartilage and the menisci) this section, we will describe many of the preven- was 6.4 times greater for non-braced skiers in com- tion methods and neuromuscular training programs parison to braced skiers (Kocherc et al., 2003). and provide broad instructions and guidelines for the exercises. In addition, we will review as many components of the successful, and unsuccessful, Targeting participation in ACL injury programs as possible within the specifi c purview of interventions to individuals or teams ACL injury prevention in athletes. There appears to be a measurable effect of neu- Athletes at the greatest risk of ACL injury should romuscular training interventions on the reduction participate in neuromuscular training interven- of severe knee and ACL injuries. A comprehensive tions to decrease the risk of injuring this important review of the literature revealed that fi ve of the ligament. This approach is specifi c to the individ- six studies demonstrated neuromuscular training ual athlete. The neuromuscular training protocol reduced lower extremity injury risk, four of the should preferably be designed and instituted specifi - six studies found neuromuscular training reduced cally for and with athletes selected for neuromus- serious knee injury risk and three of the six cular training based on identifi ed neuromuscular reported decreased ACL injury risk (Hewett et al., defi ciencies and imbalances (Table 5.3). 2006c). The components of the most successful In order to correct ligament dominance in programs are summarized later. In sum, plyomet- female athletes (Table 5.3), a neuromuscular train- ric training and biomechanical analysis of landing, ing program must be designed to teach the athlete cutting, and jumping technique were common to control dynamic knee motion in the coronal components of the studies that were effective at (abduction and valgus) plane. The fi rst concept reducing the risk of ACL injury in athletes. that the athlete and coach are taught is the knee 62 Chapter 5

Table 5.3 Injury prevention matrix applied to ACL injury prevention: potential measures to prevent injuries.

Pre-injury Injury Post-injury

Athlete Sex/gender Training status Rehabilitation Body Mass Index Falling techniques Restoration of neuromuscular function Neuromuscular imbalance Safe technique and 1. Ligament dominance: biomechanics –Technique/biomechanics 2. Quadriceps dominance: –Hamstrings power 3. Leg dominance: single leg balance/symmetry –“Core”/trunk instability –Trunk control training Surroundings Floor friction Safety nets Emergency medical Playing rules coverage Equipment Shoe friction and torsional Knee brace First aid equipment resistance with the playing Tape Ambulance surface Ice is a single-plane hinge, not a ball-and-socket joint. These imbalances are addressed throughout the Reeducation of the female neuromuscular system entire training protocol. Equal leg-to-leg strength, away from multi-planar motion of the knee to balance and foot placement are stressed through all dynamic control of knee motion in the sagittal the neuromuscular training exercises. In order to plane only is achieved through a progression of correct for leg dominance, the neuromuscular train- single, then multi-planar exercises. ing must progressively emphasizes double then sin- Quadriceps dominance (Table 5.3) can be cor- gle movements through progressive training phases. rected through the use of exercises that emphasize Finally, “core” or trunk/pelvis instability, as evi- co-contraction of the knee fl exor (hamstrings) and denced by increased trunk motion, must be cor- extensor (quadriceps) muscles. It is a challenging rected in those female athletes who demonstrate task to develop more appropriate fi ring patterns instability with the latest core stability training for the knee fl exors, while utilizing exercises that techniques. These include progressive neuromus- also strongly activate the knee extensors. At angles cular training techniques that target the balanced greater than 45º, the quadriceps is an antagonist and synchronized turn-on of the dynamic stabi- to the ACL. Therefore, it is important to use deep lizing musculature of the trunk, pelvis and hip. knee fl exion angles to put the quadriceps into an Unstable surfaces, single-leg balancing and pertur- ACL agonist position. By training the athlete with bation training should be employed (Table 5.3). deep knee fl exion jumps, she learns to increase the The authors realize that the individualized amount of knee fl exion and decrease the amount approach may not be tenable for team athletes and of time in the more dangerous straight-legged their coaches. Though we do not know if the gen- position. At the same time the athlete can repro- eralizations from our systematic review of the lit- gram peak fl exor/extensor fi ring patterns, increas- erature discussed earlier apply to all athletes or just ing co-fi ring and quadriceps fi ring in deep fl exion those that participate in jumping, landing and cut- for greater protection of the ACL. ting sports; we can assume that there will be posi- Dominant leg imbalance can be addressed in the tive effects of neuromuscular training programs female athlete via exercises that force the correction designed around these basic commonalities in of dynamic contralateral imbalances (Table 5.3). effective interventions. These broad generalizations Preventing knee injuries 63 for the athlete in cutting and landing sports, for Plyometrics may be used as combined analysis “team training” from the studies discussed above and training tools, with verbal or visual feedback, should be effective if plyometrics and landing, cut- for control of body motion, both during decel- ting and jumping technique training are included eration and acceleration, and knee loading, espe- in the intervention. cially with respect to the reduction of abduction (or “valgus”) torque about the knee. For example, Plyometrics is an important component Hewett et al. (1996, 1999, 2006a) have shown that for reduction of ACL injury risk in tuck jumps force control of knee abduction torque athletes (Box 5.1). The other exercises that were included in the interventions that reported decreased ACL The evidence for including a plyometric com- injury risk were lateral jumps over barriers (this ponent as a portion of an ACL injury prevention forces trainees to stabilize their trunk in the coro- program is relatively strong. A systematic review nal plane while moving both lower extremities of the literature found that reduced ACL injury side-to-side), landing and balancing on compliant risk occurred in those interventions that included surfaces and perturbed single-leg balancing and plyometrics as part of the training program, while hop and holds for extended periods (Box 5.1). those that did not include plyometrics did not reduce an ACL injury risk (Hewett et al., 2006c). Movement biomechanics, technique The focus of plyometrics should be on proper land- and education components: coronal ing, cutting, and jumping techniques and body plane is key mechanics during these movements. Training programs that incorporate plyometrics result in safe The evidence in support of including movement levels of varus or valgus stress about the knee, and biomechanics, landing, cutting and jumping tech- may increase “muscle dominant” and reduce “liga- nique, and education components of the effective ment dominant” neuromuscular control patterns interventions is also relatively strong. Olsen et al. while correcting for these and other neuromuscu- (2005) have reported that in sports performed on lar imbalances in athletes (Table 5.3). court and turf surfaces most ACL injuries occur Studies by Hewett et al. (1996, 1999, 2006a), by non-contact mechanisms during landing and Myklebust et al. (2003), and Mandelbaum et al. lateral pivoting. The biomechanics of these land- (2005) all incorporated high intensity plyometric ing and cutting movements can be improved with movements into the design of their intervention neuromuscular training. Neuromuscular training programs (Boxes 5.1 and 5.2), but the studies by can increase coronal and sagittal plane control of Heidt et al. (2000) and Söderman et al. (2000), the lower extremity. For example, during a squat which did not reduce ACL injury risk, did not. jump (Box 5.1), a two-footed plyometric activity, This can be explained, at least in part, by the fact post training results show that lower extremity that the studies by Söderman et al. (2000) and valgus alignment can be reduced at the knee and Heidt et al. (2000) had little chance of establishing hip. Conversely, during a single-leg tasks such as if their intervention could reduce the risk of injury a hop and hold maneuver (Box 5.1), the most sig- because the sample size was likely too small and nifi cant changes may occur in the sagittal plane of from this perspective these should be considered the knee. preliminary studies. With this caveat, the stud- There is strong evidence in support of landing, ies that incorporated high intensity plyometrics cutting and jumping technique training and its reported reduced ACL injury risk, while the studies effect on reducing ACL injury risk. Hewett et al. that did not incorporate high intensity plyomet- (1996, 1999, 2006a) reported that technique and rics did not report reductions in ACL injury risk. phase-oriented training that corrected jump and Hence, the plyometric component of a pre-season landing techniques in athletes reduced ACL inju- intervention program appears to reduce serious ries in a female intervention group compared ligamentous injuries, specifi cally ACL injuries. to female controls and resulted in injury levels 64 Chapter 5

Box 5.1 Dynamic neuromuscular analysis (DNA) training program

(Courtesy of Cincinnati Children’s Hospital, www.cincinnatichildrens/sportsmed).

Athletic position The athletic position is a functionally stable position with the knees comfortably fl exed, shoulders back, eyes up, feet approximately shoulder-width apart, the body mass balanced over the balls of the feet. The knees should be over the balls Broad jump and hold of the feet and chest should be over the knees. This is the The athlete prepares for this jump in the athletic position with athlete-ready position and is the starting and fi nishing position her arms extended behind her at the shoulder. She begins for most of the training exercises. During some of the exercises by swinging her arms forward and jumping horizontally and the fi nishing position is exaggerated with deeper knee fl exion vertically at approximately a 45º angle to achieve maximum in order to emphasize the correction of certain biomechanical horizontal distance. The athlete must stick the landing with her defi ciencies. knees fl exed to approximately 90º in an exaggerated athletic position. The athlete may not be able to stick the landing during a maximum effort jump in the early phases. In this situation, have the athlete perform a sub-maximal broad jump in which she can stick the landing with her toes straight ahead and no inward motion of her knees. As her technique improves, encourage her to add distance to her jumps, but not at the expense of perfect technique.

Wall jump The athlete stands erect with her arms semi-extended 180-degree jump overhead. This vertical jump requires minimal knee ﬂ exion. The The starting position for this jump is standing erect with feet gastrocnemius muscles should create the vertical height. The shoulder width apart. She initiates this two-footed jump with a arms should extend fully at the top of the jump. Use this jump direct vertical motion combined with a 180º rotation in mid air, as a warm-up and coaching exercise as this relatively low- keeping her arms away from her sides to help maintain balance. intensity movement can reveal abnormal knee motion in athletes When she lands she immediately reverses this jump into the with poor side-to-side knee control. opposite direction. She repeats until perfect technique fails. The goal of this jump is to achieve maximum height with a full 180º rotation. Encourage the athlete to maintain exact foot position on the ﬂ oor, by jumping and landing in the same footprint.

Squat jump The athlete begins in the athletic position with her feet fl at on Tuck jump the mat pointing straight ahead. The athlete drops into deep The athlete starts in the athletic position with her feet shoulder- knee, hip and ankle fl exion, touches the fl oor (or mat) as close width apart. She initiates the jump with a slight crouch to her heels as possible, then takes off into a maximum vertical downward while she extends her arms behind her. She then jump. The athlete then jumps straight up vertically and reaches swings her arms forward as she simultaneously jumps straight as high as possible. On landing she immediately returns to up and pulls her knees up as high as possible. At the highest starting position and repeats the initial jump. Repeat for the point of the jump, the athlete is in the air with her thighs parallel allotted time or until her technique begins to deteriorate. Teach to the ground. When landing the athlete should immediately the athlete to jump straight up vertically, reaching as high begin the next tuck jump. Encourage the athlete to land softly, overhead as possible. Encourage her to land in the same spot using a toe to mid-foot rocker landing. The athlete should not on the fl oor, and maintain upright posture when regaining the continue this jump if they cannot control the high landing force deep squat position. Do not allow the athlete to bend forward or if they utilize a knock-kneed landing. at the waist to reach the fl oor. The athlete should keep her eyes

(Continued) Preventing knee injuries 65

Box 5.1 (Continued)

up, feet and knees pointed straight ahead, and have their arms X-Hops to the outside of their legs. The athlete begins faces a quadrant pattern stands, on a single limb with their support knee slightly bent. She hops diagonally, lands in the opposite quadrant, maintains forward stance and holds the deep knee fl exion landing for 3 s. She then hops laterally into the side quadrant and again holds the landing. Next she hops diagonally backward and holds the jump. Finally, she hops laterally into the initial quadrant and holds the landing. She Broad Jump to Vertical Jump repeats this pattern for the required number of sets. Encourage The athlete performs three successive broad jumps, and the athlete to maintain balance during each landing, keeping her immediately progresses into a maximum effort vertical jump. eyes up and visual focus away from their feet. The three consecutive broad jumps should be performed as quickly as possible and attain maximal horizontal distance. The third broad jump should be used as a preparatory jump that will allow horizontal momentum to be quickly and effi ciently transferred into vertical power. Encourage the athlete to provide minimal braking on the third and fi nal broad jump to ensure that maximum energy is transferred to the vertical jump. Coach the athlete to go directly vertical on the fourth jump and not move horizontally. Utilize full arm extension to achieve maximum vertical height.

Single Leg Balance The balance drills are performed on a balance device that provides an unstable surface. The athlete begins on the device with a two-leg stance with feet shoulder width apart, in athletic position. As the athlete improves the training drills can incorporate ball catches and single leg balance drills. Encourage the athlete to maintain deep knee fl exion when performing all balance drills. Hop and Hold The starting position for this jump is a semi-crouched position on a single leg. Her arms should be fully extended behind her at the shoulder. She initiates the jump by swinging the arms forward while simultaneously extending at the hip and knee. The jump should carry the athlete up at an approximately 45º angle and attain maximum distance for a single-leg landing. Athletes are instructed to lands on the jumping leg with deep knee fl exion (to 90º). The landing should be held for a minimum of 3 s. Coach this jump with care to protect the athlete from injury. Start her Bounding with a submaximal effort on the single leg broad jump so she can The athlete begins this jump by bounding in place. Once she experience the level of diffi culty. Continue to increase the distance attains proper rhythm and form encourage her to maintain the of the broad hop as the athlete improves her ability to stick and vertical component of the bound while adding some horizontal hold the fi nal landing. Have the athlete keep her visual focus away distance to each jump. The progression of jumps progresses from her feet, to help prevent too much forward lean at the waist. the athlete across the training area. When coaching this jump, encourage the athlete to maintain maximum bounding height. 66 Chapter 5 similar to a male control group. Myklebust and Bahr study found a decrease in traumatic lower extrem- (2005) reported that the incidence of ACL injury in ity injuries, none of these interventions reduced elite handball was reduced with training designed ACL injury risk. Methods for altering biomechani- to improve awareness of lower extremity align- cal technique include those of Hewett et al. (1996, ment and knee control during cutting and landing 1999, 2006a) that utilized a trainer to provide feed- activities (Box 5.2). The studies by Hewett et al. back and awareness to an athlete during training, (1996, 1999, 2006a), Mandelbaum et al. (2005), and Myklebust and Bahr (2005) that utilized part- and Myklebust and Bahr (2005), which successfully ner training to provide the critical feedback regard- reduced ACL injury risk, all incorporated landing ing lower extremity alignment, particularly valgus technique analysis and feedback during training (inward) positioning of the knee (Figure 5.7). into their intervention programs. Of the non-effec- Johnson (2001) reported that education and public tive studies, none incorporated landing/cutting tech- awareness of the high occurrence and mechanisms nique and while only the Wedderkopp et al. (2003) of ACL injury can decrease injuries in alpine skiers by

Box 5.2 ACL prevention program for team handball

(Courtesy of the Oslo Sports Trauma Research Center, www.ostrc.no). Floor exercises Mat exercises Week 1: Running and planting, partner running backward Week 1: Two players standing on one leg on the mat throwing and giving feedback on the quality of the movement, change to each other. position after 20 s. Week 2: Jump shot from a box (30–40 cm high) with a two-foot Week 2: Jumping exercise—right leg–right leg over to left landing with fl exion in hip and knees. leg–left leg and fi nishing with a two-foot landing with fl exion in Week 3: “Step” down from box with one-leg landing with fl exion both hips and knees. in hip and knee. Week 3: Running and planting (as week 1), now doing a full Week 4: Two players both standing on balance mats trying to plant and cut movement with the ball, focusing on knee push partner out of balance, fi rst on two-legs, then on one leg. position. Week 5: The players jump on a mat catching the ball, then take Week 4: Two and two players together two-leg jump forward a 180º turn on the mat. and backwards, 180º turn and the same movement backward. Partner tries to push the player out of control but still focusing on landing technique. Week 5: Expanding the movement from week 3 to a full plant and cut, then a jump shot with two-legged landing.

(Continued) Preventing knee injuries 67

Box 5.2 (Continued)

Wobble board exercises Week 1: Two players two-legged on the board throwing to each other. Week 2: Squats on two legs, then on one leg. Week 3: Two players throwing to each other, one foot on the board. Week 4: One foot on the board, bouncing the ball with their eyes shut. Week 5: Two players, both standing on balance boards trying to push partner out of balance, ﬁ rst on two legs, then on one leg.

greater than 50%. A reduction of ACL injuries in ski instructors was achieved by using “guided learning” techniques that educated skiers to avoid “high risk” skiing positions, such as the skier positioned with a majority of the weight on the downhill ski and their hips below their knees. This approach is supported by ﬁ ndings that verbal or visual or bio-feedback regarding technique may decrease reaction forces at the knee and reduce ACL injuries.

Single leg balancing component and ACL injury risk

Though single leg balance training alone may not be effective for decreasing ACL injury rates in female athletes, as the small studies that incorporated single leg balancing alone did not report decreased ACL injury risk in female athletes, it may be an important component of neuromuscular training designed Figure 5.7. Hip and knee control. In single leg squats and to decrease non-contact ACL injury. The studies by balance training exercises the athlete should maintain a Hewett et al. (1996, 1999, 2006a) and Mandelbaum straight line through the hip, knee, and toe. She should et al. (2005) incorporated single leg stability training, keep a horizontal orientation of the hips and avoid a pelvic tilt during one legged squat, balance exercises, etc. primarily utilizing hold positions from a decelerated Encourage the athlete to reach deep knee ﬂ exion when landing. Single leg stability can be gained with bal- performing these drills ance training on unstable surfaces. Myklebust and 68 Chapter 5

Bahr (2005) utilized partner training on Airex mats, suggests that resistance training may reduce wobble boards or the fl oor (Box 5.2). Again, however, injury based on benefi cial adaptations that occur the intervention programs that used balance training in bones, ligaments, and tendons after training. in isolation were not effective in reducing knee inju- For example, Lehnhard et al. (1996) signifi cantly ries in females. Wedderkopp et al. (2003) reported a reduced injury rates with a strength training regi- reduction in all soccer-related injuries, though not men in men’s soccer. The studies by Hewett et al. knee or ACL injuries. Söderman et al. (2000) were (1996), Kocher et al. (2003), Myklebust et al. not effective in reducing injuries in female soccer (2003), and Mandelbaum et al. (2005) incorporated players. Wedderkopp et al. (2003) and Söderman strength training in their intervention protocols. et al. (2000) focused on balance training, primarily Myklebust and Bahr (2005), Heidt et al. (2000), utilizing unstable wobble boards. Therefore, balance and Söderman et al. (2000) did not include training alone may not be as effective for ACL injury strength training in their interventions. The prevention as when it is combined with other types designs that incorporated strength training were of training. Interestingly, Caraffa et al. (1996) studied among the most effective at decreasing ACL injury male soccer players and showed a signifi cant effect rates. But strength training in isolation may not of balance board exercises on reducing ACL injury be a pre-requisite for prevention, as the Myklebust and reported that balance training may be more and Bahr (2005) study was effective in reducing effective in males than females. ACL injury risk and it did not incorporate strength training. In the fi nal analysis, weight training A core component? Evidence for the alone has not been reported to be effective at effects of “core stability” training decreasing ACL injury rates and may not need to be incorporated into a successful intervention. It is There is not clear evidence whether “core stability” important for us to point out that this may apply exercises should be incorporated into an interven- only to those subjects who have adequate strength tion to reduce knee ligament injuries. It is not clearly prior to entering an injury prevention program. defi ned what “core stability” exercises actually represent and what their effects are on the muscles that stabilize the trunk, hip, and pelvis. However, Zazulak The proper “training dose:” How much et al. (2007) demonstrated that measures of “core” and how often interventions should be or trunk proprioception and displacement predicted performed risk of ACL injury in collegiate athletes with high Neuromuscular power can increase within 6 weeks sensitivity and specifi city. Interestingly, this effect of training and may result in decreases in peak was observed in female, but not male, collegiate ath- impact forces and knee abduction torques. The letes. This may indicate the need for including trunk evidence from the literature indicates that training perturbation and strengthening in optimal interven- sessions should be performed more than one time tional training programs. The fi ndings support the per week, preferably at least two and up to fi ve integration of proprioceptive stability training in ACL times per week. The total pre-season training dura- injury interventions, at least for females. Krosshaug tion of the intervention program should be a min- et al. (2007) suggested that preventive programs to imum of 6, preferably 8 or more, weeks in length. enhance knee control should focus on avoiding val- Pfeiffer et al. (2006) reported that 20 min of “in- gus motion about this joint and include distractions season” exercise 2 days per week was not suffi - resembling those seen in match situations. cient to decrease an ACL injury risk in high school age female basketball players. Gilchrist et al. Strength training effects on ACL (2008) also reported that an “in-season” program, injury risk with no “pre-season” component was only effective in the last half of the season. Resistance training alone has not been shown to The most effective programs are progressive in reduce ACL injuries. However, inferential evidence nature. Exercises should progress to techniques Preventing knee injuries 69 that initiate perturbations that force the athlete training and education programs are likely to be an to decelerate and control the body in order to effective solution to the problem of gender inequity successfully perform the landing, cutting and in ACL injury. Selective combination of neuromus- jumping techniques. The intervention should pref- cular training components may provide additive erably be phasic in nature. Three exercise phases, effects, further reducing the risk of ACL injuries. such as technique, power, and performance phases It appears that plyometric power and biome- are often utilized to facilitate progressions designed chanics technique training specifi c to landing, to improve the athletes’ ability to control body cutting and jumping activities can induce neu- motion during dynamic activities. All exercises in romuscular changes and prevent ACL injury, at each phase should be progressed to exercise tech- least in female athletes. Balance, core stability, and niques that incorporate perturbations that force strength training may be useful adjuncts. However, the athlete to decelerate and control the body in we do not yet know which of these components multiple planes of motion, particularly the coronal are most effective or whether their effects are com- plane, in order to successfully perform each tech- binatorial. Future research efforts will assess the nique with optimal form and safety level. relative effi cacy of these interventions alone and in Several studies have highlighted the importance combination in order to achieve the optimal effect of the athlete’s fi tness with regard to prevention of in the most effi cient manner possible. Selective injuries. In relation to ACL injuries we know that in combination of neuromuscular training compo- addition to strength, endurance, and general fi tness nents may provide additive effects, further reduc- it is highly recommended to improve every ath- ing the risk of ACL injuries in female athletes. lete’s sport specifi c skills. This includes more “ACL- Neuromuscular training interventions designed friendly” movements in the different sports, such as to prevent injury should be based on the previously a two footed landings after a jump and two- to three- published literature. Final conclusions are that neu- step stop instead of a one-step stop and pivoting. romuscular and educational training reduce ACL Finally, fair play is an important factor in our injury risk in females athletes if: plyometric exercises work for less serious injuries. In contact sports and biomechanical technique training are incorpo- sometimes ACL injury is produced by brutal and rated into the protocol, training sessions are per- unfair play. This is an educational and attitude formed more than 1 time per week and the duration challenge for coaches and offi cials. of the training program is a minimum of 6 weeks in length. The studies by Hewett et al. (2006b), Take-home message Myklebust and Bahr (2005), and Mandelbaum et al. (2005) all incorporated plyometrics and biome- There is good evidence that neuromuscular training chanical movement analysis and feedback into their decreases ACL injury incidence in female athletes. injury prevention programs and applied these basic Plyometrics in combination with biomechanics and rules of proper intervention “dose.” technique (e.g., jumping/landing) training appear to induce neuromuscular changes that reduce ACL injury risk. Increased lower extremity muscle References recruitment and strength likely have a direct effect on the loading of the ACL during activities that Albright, J.P., Powell, J.W., Smith, W., Martindale, A., involve cutting and landing. Though ACL injuries Crowley, E., Monroe, J., Miller, R., Connolly, J., Hill, B.A., likely occur too quickly (less than 70 ms) for refl ex- Miller, D. (1994) Medial collateral ligament knee sprains ive muscular activation (greater than 100 ms), ath- in college football. Effectiveness of preventive braces. letes can adopt preparatory muscle recruitment and American Journal of Sports Medicine 22, 12–18. Caraffa, A., Cerulli, G., Projetti, M., Aisa, G., Rizzo, A. movement patterns that reduce the incidence of (1996) Prevention of anterior cruciate ligament injuries caused by unexpected perturbations. The injuries in soccer. A prospective controlled study studies discussed earlier provide strong, but not une- of proprioceptive training. Knee Surgery Sports quivocal, evidence that neuromuscular intervention Traumatology and Arthroscopy 4, 19–21. 70 Chapter 5

Heidt Jr., R.S., Sweeterman, L.M., Carlonas, R.L., incidence of ACL injuries in female athletes: 2-year follow Traub, J.A., Tekulve, F.X. (2000) Avoidance of soccer up. American Journal of Sports Medicine 33, 1003–1010. injuries with preseason conditioning. American Journal Myklebust, G., Bahr, R. (2005) Return to play guidelines of Sports Medicine 28, 659–662. after anterior cruciate ligament surgery. British Journal Hewett, T.E., Ford, K.R., Myer, G.D. (2006a) Anterior of Sports Medicine 39, 127–131. cruciate ligament injuries in female athletes: Part 2, A Myklebust, G., Engebretsen, L., Braekken, I.H., Skjølberg, meta-analysis of neuromuscular interventions aimed at A., Olsen, O.E., Bahr, R. (2003) A prospective cohort injury prevention. American Journal of Sports Medicine study of anterior cruciate ligament injuries in elite 34, 490–498. Norwegian team handball. Scandinavian Journal of Hewett, T.E., Myer, G.D., Ford, K.R. (2006b) Anterior Medicine and Science in Sports 8, 149–153. cruciate ligament injuries in female athletes: Part 1, Olsen, O.E., Myklebust, G., Engebretsen, L., Holme, I., Mechanisms and risk factors. American Journal of Sports Bahr, R. (2005) Exercises to prevent lower limb injuries Medicine 34, 299–311. in youth sports: cluster randomised controlled trial. Hewett, T.E., Myer, G.D., Ford, K.R., Slauterbeck, J.L. (2006c) British Medical Journal 330, 449. Preparticipation physical exam using a box drop vertical Pfeiffer, R.P., Shea, K.G., Roberts, D., Grandstrand, S., jump test in young athletes: the effects of puberty and Bond, L. (2006) Lack of effect of a knee ligament injury sex. Clinical Journal of Sports Medicine 16, 298–304. prevention program on the incidence of noncontact Hewett, T.E., Paterno, M.V., Noyes, F.R. (1999) Differences anterior cruciate ligament injury. Journal of Bone and in single leg balance on an unstable platform between Joint Surgery Am 88, 1769–1774. female and male normal, ACL-defi cient and ACL- Sitler, M., Ryan, J., Hopkinson, W., Wheeler, J., reconstructed knees. In S. Lephardt, F.H. Fu (eds.) Santomier, J., Kolb, R., Polley, D. (1990) The effi cacy Proprioception and Neuromuscular Control in Joint of a prophylactic knee brace to reduce knee injuries Stability, pp. 77–88. Human Kinetics, Champaign, IL. in football. A prospective, randomized study at West Hewett, T.E., Stroupe, A.L., Nance, T.A., Noyes, F.R. (1996) Point. American Journal of Sports Medicine 18: 310-315. Plyometric training in female athletes. Decreased Söderman, K., Werner, S., Pietilä, T., Engström, B., impact forces and increased hamstring torques. Alfredson, H. (2000) Balance board training: American Journal of Sports Medicine 24, 765–773. prevention of traumatic injuries of the lower Gilchrist, J., Mandelbaum, B.R., Melancon, H., Ryan, G.W., extremities in female soccer players? A prospective Silvers, H.J., Griffi n, L.Y., Watanabe, D.S., Dick, R.W., randomized intervention study. Knee Surgery Sports Dvorak, J. (2008) A randomized controlled trial to Traumatology and Arthroscopy 8, 356–363. prevent noncontact anterior cruciate ligament injury Wedderkopp, N., Kaltoft, M., Holm, R., Froberg, K. (2003) in female collegiate soccer players. American Journal of Comparison of two intervention programmes in Sports Medicine 36(8), 1476–83. young female players in European handball—with and Johnson, R.J. (2001) The ACL injury in female skiers. In without ankle disc. Scandinavian Journal of Medicine and L.Y. Griffi n (ed.) Prevention of Noncontact ACL injuries, Science in Sports 13, 371–375. pp. 107–111. American Academy of Orthopaedic Zazulak, B.T., Hewett, T.E., Reeves, N.P., Goldberg, B., Surgeons, Rosemont. Cholewicki, J. (2007) Defi cits in neuromuscular control Kocher, M.S., Sterett, W.I., Briggs, K.K., Zurakowski, D., of the trunk predict knee injury risk: a prospective Steadman, J.R. (2003) Effect of functional bracing on biomechanical-epidemiologic study. American Journal subsequent knee injury in ACL-defi cient professional of Sports Medicine 35, 1123–1130. skiers. Journal of Knee Surgery 16(2), 87–92. Krosshaug, T., Slauterbeck, J.R., Engebretsen, L., Bahr, R. (2007) Biomechanical analysis of anterior cruciate Further reading ligament injury mechanisms: three-dimensional motion reconstruction from video sequences. Scandinavian Journal of Medicine and Science in Sports 17, 508–519. Griffi n, L.Y. (ed.) (2001) Prevention of Noncontact ACL Lehnhard, H.R., Young, S., Butterfi eld, S.A. (1996) injuries. American Academy of Orthopaedic Surgeons, Monitoring injuries on a college soccer team: the effect Rosemont. of strength training. Journal of Strength and Conditioning Hewett, T.E., Yearout, K., Manske, R. (2006) Preventing Research 10, 115–119. injury to the anterior cruciate ligament. In R. Manske Mandelbaum, B.R., Silvers, H.J., Watanabe, D.S., Knarr, J.F., (ed.) Postsurgical Orthopedic Sports Rehabilitation: Knee Thomas, S.D., Griffi n, L.Y., Kirkendall, D.T., Garrett Jr., W. and Shoulder, pp. 319–336. Mosby, St. Louis, MO. (2005) Effectiveness of a neuromuscular and Hewett, T.E. (2007) An introduction to understanding proprioceptive training program in preventing the and preventing ACL injury. In Hewett T.E., Schultz, S.J., Preventing knee injuries 71

Griffi n, L.Y. (Eds) Understanding and preventing non-contact S.M. Lephart, F.H. Fu (eds.) Proprioception and ACL injury, p. xxi-xxviii. Human Kinetics, Champaign, IL. Neuromuscular Control in Joint Stability, pp. 77–88. Hewett, T.E., Myer, G.D., Ford, K.R. (2007) Theories Human Kinetics, Champaign, IL. on how neuromuscular intervention programs Hewett, T.E., Zazulak, B.T. (2007) The costs associated may infl uence ACL injury rates: changing landing with ACL injury. In T.E. Hewett, S.J. Schultz, & techniques and improving balance in intervention L.Y. Griffi n (eds.) Understanding and Preventing Non- studies. In T.E. Hewett, S.J. Schultz, L.Y. Griffi n (eds.) contact ACL Injury, pp. 47–56. Human Kinetics, Understanding and Preventing Non-contact ACL Injury, Champaign, IL. pp. 75–90. Human Kinetics, Champaign, IL. Hewett, T.E., Zazulak, B.T., Myer, G.D. (2007) Theories on Hewett, T.E., Myer, G.D., Ford, K.R., Slauterbeck, J.R. how neuromuscular interventions may infl uence ACL (2007) Dynamic neuromuscular analysis training for injury rates: EMG activity, muscle fi ring patterns, and preventing anterior cruciate ligament injury in female pre-activation. In T.E. Hewett, S.J. Schultz, L.Y. Griffi n athletes. Instructional Course Lectures 56, 397–406. (eds.) Understanding and Preventing Non-contact ACL Hewett, T.E., Paterno, M.V., Noyes, F.R. (2000) Injury, pp. 173–182. Human Kinetics, Champaign, IL. Neuromuscular contributions to knee kinematics and kinetics: normal ve rsus the pathological state. In Chapter 6 Preventing hamstring injuries Geoffrey M. Verrall1, Árni Árnason2 and Kim Bennell3

1SPORTSMED.SA, Sports Medicine Clinic, Adelaide, Australia 2Department of Physiotherapy, University of Iceland, Reykjavik, Iceland 3Centre for Health, Exercise and Sports Medicine, School of Physiotherapy, University of Melbourne, Australia

Australian Rules football, and American football Epidemiology of hamstring injuries (Table 6.1). The incidence of hamstring muscle in sports strain injuries has changed with studies from the 1980s indicating that ankle sprains were the most Introduction common type of injury in soccer, followed by knee sprains or hamstring strains. The more recent soccer The hamstring muscle group consists of three mus- studies indicate that the proportion of hamstring cles of the posterior thigh, the biceps femoris, semi- strains has increased with most modern studies indi- tendinosus, and semimembranosus muscles. Their cating that hamstring strains are the most common action is to extend the hip and ﬂ ex the knee and injury in soccer (Hawkins & Fuller, 1999). Where all three muscles are supplied by the sciatic nerve. data is available this trend has also been reﬂ ected in In understanding the etymology of the word, ham the epidemiology of injury for all football codes. refers to the hollow on the back of the human knee with string referring to the tendons that are present.

Table 6.1 Risk of hamstring strains in different sports. Epidemiology of hamstring injuries The numbers reported are average estimates based on in sports the studies available.

2 Hamstring muscle strains are common injuries Sport Competition Training Rank incidence1 incidence1 in sports that have movement requirements with sudden acceleration and maximal sprinting. These Sprinting 1 (28.6–38%) include sports such as athletic sprinting and all of Rugby 5.6 0.3 1–2 (9.7–10.7%) Australian 3.7–8.6 NA 1 (13.7–23.8%) the football codes. Additionally in sports where the Rules football hamstring muscles are stretched beyond the usual Soccer male 2.4–4.1 0.4–0.7 1–2 movement of the muscles, in particular hip ﬂ ex- (11.0–16.5%) ion, also have a high frequency of hamstring mus- Soccer female NA NA 2 (13.1%) cle injury. Sports in this particular group include American NA NA 2 (4.9%) football dancing and waterskiing. Hamstring strains are the ﬁ rst or second ranked injury in terms of injury inci- 1 Incidence is reported for adult, competitive athletes as the dence in the football codes such as soccer, rugby, number of injuries per 1000 hours of training and competition. NA: Not available. 2 Sports Injury Prevention, 1st edition. Edited by R. Bahr and Rank indicated the relative rank of this injury within the sport L. Engebretsen Published 2009 by Blackwell Publishing in question, as well as the proportion as a percentage of total ISBN: 9781405162449 number of injuries within the sport.

72 Preventing hamstring injuries 73

the case for elite level athletes as MRI has recently been shown to have some ability in predicting injury prognosis (Slavotinek et al., 2002; Connell et al., 2004). Athletes that have posterior thigh injuries with negative MRI scan results for hamstring muscle injury have a much better prognosis with respect to an earlier return to sport and a marked decrease in injury recurrence rate when compared to athletes with posterior thigh injuries and positive MRI scan results with respect to hamstring muscle injury (Verrall et al., 2003).

Time loss from hamstring injuries

Figure 6.1. Hamstring injury with resultant posterior In soccer, Australian Rules football and rugby the thigh bruising. This injury, although spectacular in average absence from competition due to hamstring appearance, is uncommon, especially with acceleration/ running hamstring injuries muscle strain injury has been shown to be 17–25 days, with athletes generally missing 2–3 weekly matches. However due to the troublesome nature of these injuries the range of days of absence can be Diagnosis of hamstring injuries considerably higher. These fi gures are derived from The diagnosis of hamstring muscle strain injury studies on hamstring muscle injury in these sports. generally involves the sudden onset of posterior Many sports have no available data on the effect on thigh pain whilst accelerating/sprinting. Usually athletes due to hamstring injury. In Australian foot- the athlete cannot compete further due to the ball there is a high recurrence rate for re-injury with injury and has varying degrees of dysfunction over studies demonstrating that this can be as high as the subsequent days/weeks depending on the sever- 35%. Similar recurrent injury rates can also be seen ity of the injury. Pain on resisted hamstring con- in soccer with studies demonstrating re-injury rates traction is the most common clinical sign with the of between 12% and 35%. Other sports have not frequency of thigh tenderness and the presence of completed research in this important area but it is visible bruising being variable (Figure 6.1) (Verrall likely that recurrent injuries would be common. et al., 2003). Traditionally clinical diagnosis has been In elite level soccer approximately three injuries used in scientifi c studies to signify the presence of can be expected per 1000 playing hours (Árnason hamstring muscle strain injury. However recent use et al., 2004). A team playing 50 matches per sea- of imaging, in particular MRI, has demonstrated son results in approximately 800 h of match play- that there may be variation in the classical previ- ing time. Therefore it is expected that on average ously accepted clinical picture. Some cases vary that each team will have two to three injuries per by demonstrating a hamstring injury on imaging year during matches, as well as one to two during despite an insidious onset of injury with few clini- training (see later). In practice it is demonstrated, cal signs, whereas others demonstrate no hamstring and this data derives from Australian Rules foot- injury despite classical clinical signs suggesting ball, that there is much variation in the incidence in these cases a different etiology for the posterior of injury between teams. At this stage it is unclear thigh pain (Verrall et al., 2003). From this it can be whether sub-elite or club level results in a lower, stated that when reporting research on hamstring or higher, frequency of hamstring injury. Younger injuries, imaging should be used to verify the injury teams, underage athletes, have been demonstrated but for general day-to-day management of injured to have fewer hamstring muscle injuries. athletes with the common mechanism of injury, The most commonly injured hamstring muscle clinical judgement should suffi ce. This may not be is the biceps femoris (long head) muscle, followed 74 Chapter 6 by the semitendinosus and semimembranosus soccer. These studies have varied in their size and muscles. This may in part be dependent on the methodology with differing injury defi nitions and mechanism of the hamstring injury but in many statistical analyses being used, thereby making it cases more than one hamstring muscle is injured diffi cult to be conclusive about the fi ndings that in any single muscle injury. At this time the impli- these studies have generated. However some fi nd- cations with respect to athlete return to sport and ings have been similar in nearly all the studies that recurrence rate is not known when comparing sin- have been conducted. In particular the two most gle or multiple muscle injuries. It is known that the consistent fi ndings associated with hamstring strain larger the demonstrated muscle injury, the worse injury include having a history of a previous ham- prognosis the athlete has (Verrall et al., 2006) but string strain injury and being of older age. A sum- whether for the same size injury to have one mus- mary of internal and external risk factors can be cle injured or more than one muscle injured and seen in Table 6.2. affect on athlete prognosis is unclear at this time. Imaging studies have demonstrated that ham- Previous hamstring strain injury string muscle injuries, in fact all muscle strain injuries, involve the musculotendinous junc- Studies on risk factors for hamstring strain injury tion (Garrett, 1996; Slavotinek et al., 2002). Some have consistently demonstrated that previous hamstring muscle injuries only involve the proxi- hamstring strain injury is a principal risk factor mal or distal tendons, this is less than 10% of the for hamstring muscle strain injury. In elite soccer total number of hamstring strain injuries. With the risk for hamstring injury has been shown to the majority of hamstring muscle strain inju- increase by between 3.5 and 11.6 times for previ- ries involving the biceps femoris the injury loca- ously injured players compared to players without tion is evenly divided to above (proximal muscle previous hamstring injury (Árnason et al., 2004). injury) and below (distal muscle injury) the short In Australian football a previous hamstring injury head of biceps insertion into the long head of the has been shown to increase hamstring injury risk biceps femoris (Slavotinek et al., 2002; Connell by 2.1–6.3 times the risk for previously uninjured et al., 2004). Although research is incomplete on players (Verrall et al., 2001). Reports from studies this area there does not appear to be a large differ- of several sports show that re-injury rates are high ence in athlete prognosis when comparing higher and this demonstrates the troublesome nature of injuries to lower injuries. This does not apply to hamstring muscle strain injuries. proximal tendon injuries as these athletes do have It is considered that the presence of a previ- a signifi cantly worse prognosis with respect to ous injury predisposes to future injury by chang- return to sport. The exception to this is where the ing the muscle properties so that following injury hamstring muscle is injured in an overstretched and subsequent athlete rehabilitation and muscle type mechanism, such as dancing and waterskiing. repair the muscle is less able to absorb force mak- These athletes are more likely to have a proximal ing it more prone to re-injury. In effect the scar- muscle/tendon injury. ring of the muscle affects the muscle properties particularly in attenuating force from the muscle to the tendon making the entire muscle at Key risk factors: how to identify increased risk for re-injury (Taylor et al., 1993). athletes at risk The proposed mechanism of this is considered in more detail later in this chapter. It is also possible that risk factors that originally placed the athlete Despite the high incidence of hamstring strains in at risk are still in operation. several popular sports, research on their specifi c risk Some limitations to this evidence exist in that factors is limited. Most studies that measure risk fac- it is not known for how long a previous ham- tors for hamstring strains have been performed on string injury will predispose to a future injury and male subjects in Australian Rules football and the proposed mechanism of increased injury risk Preventing hamstring injuries 75

Table 6.2 Internal and Risk factor Relative risk/ Evidence2 Comments external risk factors for odds ratio1 hamstring strains in different sports. The numbers reported Internal risk factors are average estimates based Previous hamstring strain 2.1–11.6 ϩϩ Good prospective studies on the studies available. Previous strains Ͼ21.8 cm3 2.3 ϩ Measured with MRI Previous knee injury 5.6 ϩ Increased age 1.1–1.4 ϩϩ Independent of previous hamstring injury Race Aboriginal descent in Australian 11.2 ϩ Single study football Black players in soccer NA ϩ Single study Decreased hamstring muscle NA ϩ Confl icting research strength results Hamstring muscle fl exibility NA 0 Poor studies Gender NA 0 No research available External risk factors Muscle fatigue NA ϩ Observational studies Higher level of competition play NA ϩ Observational studies Insuffi cient warm-up NA 0 No evidence Player position NA ϩ Observational studies

1 Relative risk/odds ratio indicates the increased risk of injury to an individual with this risk factor relative to an individual who does not have this characteristic. A relative risk of 1.2 times means that the risk of injury is 20% higher for an individual with this characteristic. NA: Not available. 2 Evidence indicates the level of scientifi c evidence for this factor being a risk factor for hamstring strains: ϩϩ—convincing evidence from high-quality studies with consistent results; ϩ—evidence from lesser quality studies or mixed results; 0—expert opinion without scientifi c evidence. has not been studied in any detail at this point Studies have shown that with increased age in time. there will be a reduction in the cross-sectional area Older age of athlete of skeletal muscles, considered to be primarily as a consequence of a reduction in size and number of Most studies indicate that increased age is a risk Type II muscle fi bers. It is muscles with predomi- factor for hamstring strains in adult male soccer nance of Type II muscles, such as the gastrocne- (relative risk/odds ratio 1.1–1.4) (Árnason et al., mius, rectus femoris, and biceps femoris, that are 2004) and Australian Rules football (relative risk/ most prone to strain injury. How a reduction in odds ratio 1.3) (Verrall et al., 2001). These ratios the number of Type II fi bers leads to an increased estimate the increase in risk for the athlete for a risk for strain injury is not entirely clear. Other 1 year increase in age. Multivariate statistical analy- studies have also reported denervation of muscle ses presented in risk factor studies suggest that this fi bers with increased age. These factors could possi- increase in risk with age is independent of whether bly predispose older athletes to hamstring strains. the athlete had a previous hamstring muscle injury. Other possible confounding factors such as previ- The incidence of hamstring strains in Australian ous hamstring strains, decreased fl exibility, and Rules football has also been shown to be higher in increased muscle fatigue could increase the risk senior players when compared to junior players. It of hamstring strains in older athletes compared is also interesting to note that in junior level, ham- to younger athletes. Although increased age itself string strain is the fourth most common injury in is not modifi able, some of these age-related con- terms of injury incidence whereas in the adult level founding factors could be modifi able and working it is the most common injury. Similar results have with these factors could possibly lower the risk of also been found in soccer. hamstring strains in older athletes. 76 Chapter 6

(a) (b)

(c)

Figure 6.2. MRI investigations of hamstrings injuries; (a) large semitendinosus muscle injury (T2 coronal view, the vertical arrow represents the proximal–distal extent of injury); (b) large semitendinosus muscle injury (T2 axial view, the vertical arrow represents the antero-posterior extent of injury, whereas the horizontal arrow represents the medio-lateral extent); (c) small biceps femoris muscle injury (T2 coronal view, the vertical arrow represents the proximal–distal extent of injury)

Size of hamstring muscle strain injury can be viewed in Figure 6.2a, b, c. The reason for this high rate of recurrence could be changes in Athletes who have incurred hamstring strains of structure or scar tissue formation in or near the large volume (larger than 20 cm3 when measured muscular tendinous junction after the previous using MRI) have been found to be at an increased injury, as scar tissue is proposed to be less func- risk of re-injury compared to athletes with ham- tional compared to the original tissue (Taylor et al., string strains of less volume (Verrall et al., 2006). 1993). Along with the scar tissue formation, atro- Examples of MRI-detected small and large hamstring phy will occur in the muscle as well as changes injuries with their subsequent size measurement in viscoelastic properties that can predispose to Preventing hamstring injuries 77 recurrent injury. Another concern is inadequate ratio. The obvious advantage of this is that it is rehabilitation as well as too early return to compet- an easily quantifi able ratio and can potentially be itive physical activity after the previous hamstring modifi ed by specifi c training of the muscle consid- strain. The risk factor, previous injury, is modifi able ered to be defi cient in strength. However further with optimal rehabilitation after hamstring strains. research needs to be performed in this area before While the optimal rehabilitation program is not there will be universal agreement as to the valid- entirely clear, it would seem advisable not to allow ity of this approach in the possible prevention athletes to participate too early after hamstring of hamstring injuries. It is also not possible to be strain in sports that require high demand on speed, specifi c about the optimal H:Q ratio and whether jumping, acceleration, deceleration, extreme ham- this ratio should be calculated using concentric or string fl exibility, etc. eccentric force production, as this have not been reliably determined. In recent years there has been Race more emphasis on the eccentric action of the hamstring muscles and many rehabilitation pro- Some studies have shown that soccer players of grams and prevention programs emphasize eccen- black origin and Australian Rules football play- tric strength training and conditioning. ers of aboriginal decent sustain signifi cantly more In interpreting the various studies, diffi culties arise hamstring strains than white players. It has been in comparing methodology on how the strength proposed that these players are generally con- of the quadriceps/hamstrings were measured, the sidered to be the fastest in their particular sport reproducibility of the method, and, more impor- when compared to their white counterparts. This tantly, what exactly constituted a hamstring injury. has lead to the conclusion that these athletes have These two factors are probably important in explain- increased risk for hamstring injury due to their ing confl icting study results (Bennell et al., 1998). muscles having a higher proportion of type II mus- In conclusion, an imbalance in muscle strength cle fi bers in order to develop faster speed. A faster between the hamstrings and quadriceps muscles is speed is considered to generate higher hamstring an area that warrants further research as it possibly stressors and this maybe the reason for increased a risk factor for hamstring injury. If this was proven injury risk. to be the case it is also an area where the risk factor may be more easily, relative to other approaches, Hamstring muscle strength and modifi able. hamstring/quadriceps strength ratio Flexibility Some studies have indicated that decreased hamstring strength, inadequate hamstring/quadriceps Many investigators have discussed the possibil- strength ratio, and a difference in right/left ham- ity that poor hamstring fl exibility could be a risk string strength ratio could be potential risk factors factor for hamstring strains. Different methods for hamstring strains. This is based on the premise are used for testing hamstring muscle fl exibility that the hamstring is weak relative to the quadri- in different studies so comparison between these ceps and therefore the leg develops too much leg studies is diffi cult. In general there is a paucity of extension force that needs to be counteracted by evidence and the methodology has been relatively the fl exion action of the hamstrings leading to poor thereby not allowing defi nitive conclusions subsequent hamstring injury. However it should be to be drawn. Although fl exibility is not as easy noted that other studies have reported results that to measure when compared to the hamstring to confl ict with these fi ndings. The studies that have quadriceps strength ratio, muscle fl exibility is also been performed all use a dynamometer to measure an area that warrants further research. If fl exibil- the concentric and eccentric strength of the ham- ity, increased or decreased, can be demonstrated to string and quadriceps with the resultant produc- be a risk factor for subsequent hamstring injury, it tion of a Hamstring to Quadriceps (H:Q) strength has the potential to be more easily modifi ed. 78 Chapter 6

Competition versus training but the increased training and playing demands of the higher levels of competition are considered to While it is generally accepted that hamstring strains in some way increase hamstring strain risk. occur more frequently during competition, as opposed to training sessions, this information is only available for a limited number of sports (Table 6.1), Player position on fi eld as research is incomplete in this area. Hamstring Player position on the fi eld of play has been shown muscle strain injuries occur more commonly in to be important in some sports including backs hav- competitive matches compared to training. It has ing a higher incidence of injury compared to for- been demonstrated that the likelihood of sustain- ward in rugby and wide receivers having a higher ing a hamstring injury during a competitive match incidence in American football. In Australian foot- as compared to during training may be increased ball and soccer the midfi eld players are considered up to 10 times in high-risk sports such as soccer to be at higher risk for hamstring muscle strain and Australian football (Garrett, 1996; Verrall et al., injury. The reason for this increased risk in these 2003). A possible reason for this is that competitive players in these sports is similar to the argument matches usually involve more intense effort over proposed to explain the increased risk seen in some a longer time period when compared to the usual ethnic groups. Players in these positions are usually training situation. This may lead to increased fatigue amongst the fastest for that particular sport. and a larger total amount of load (force) on the hamstring muscle making it more prone to injury. Insuffi cient warm-up

Muscle fatigue It is considered that an insuffi cient warm-up may increase the risk for subsequent hamstring muscle Studies from soccer show an increased incidence strain injury. The proposed mechanism for this is of hamstring strains during the last third of the that insuffi cient warm-up leads to muscles being fi rst and second half of matches (Hawkins & more viscous and less elastic with poorer neuromus- Fuller, 1999). This is generally used to indicate cular coordination. There is little or no scientifi c that fatigue may be a risk factor for hamstring evidence for this assertion, except animal stud- injury. Similar results have also been demonstrated ies showing that the load to failure is higher after in rugby and Australian football with hamstring warm-up. However, warm-up should be undertaken muscle strain injuries occurring in the latter part to adequately prepare the athlete for competition of the game or time period. and not just for an injury prevention role. Fatigued muscles have been demonstrated in laboratory studies to be able to absorb less force Take-home message than their non-fatigued counterparts (Mair et al., 1996). The absorption (attenuation) of force gen- Knowledge of potential risk factors for hamstring erated by the moving leg is a very important func- muscle strains are important for the development tion of the hamstring muscles during running. It of preventive measures. In the majority of cases, is this reduction in force attenuation that is con- the causes of hamstring strains can be considered sidered to be the reason why fatigued muscles are to be multifactorial with a complex series of events at increased risk for injury. leading to injury. In this regard there are many potential risk factors that may lead given the right Level of competition play set of conditions to a hamstring strain. Current knowledge suggests players with a previ- Studies on players from soccer and Australian Rules ous hamstring injury and older players are almost football have shown that hamstring strains are certainly at an increased risk for subsequent ham- more common in higher, more professional leagues. string muscle injury. These athletes in particu- The reasons for this have not been fully elucidated lar should be targeted for prevention programs. Preventing hamstring injuries 79

Other substantive risk factors have not as yet been injury from what would generally be considered identifi ed but the avoidance of excessive fatigue, to be normally tolerated biomechanical loads and identifying athletes with hamstring weakness and forces. We also need to examine factors that may considering the playing position and role in the increase the load tolerance of the hamstring mus- team of athletes demonstrate potential risk factors cles as this would obviously be useful in the pre- and these athletes should also be targeted for prevention of hamstring muscle strain injuries. vention programs. Finally it should be considered that different Excessive biomechanical load sports, and different athletes within those sports, probably have different risk factors. Therefore it is In some cases the mechanism, whether increased not surprising that in most studies, measurement of biomechanical load or decreased load tolerance, can a single potential risk factor almost always fails to be determined by understanding the nature of the predict hamstring muscle strain injury occurrence. sport and subsequent injury pattern. An example of a hamstring muscle strain injury in a sport where the biomechanical load obviously exceeds the load Injury mechanisms for hamstring tolerance of the hamstring muscle(s) is the typical muscle injuries water skiing injury. In this sport the typical injury occurs when the athlete is forcibly pulled over with Basic principles of hamstring muscle a forced fl exion of the trunk and a fully extended strain injury leg, usually during a starting (take-off) maneuver. This results in an excessive load on the hamstring The typical injury mechanism for hamstring mus- muscles with subsequent injury. In this case the cle strains is unknown as there is little scientifi c lit- mechanism of injury is indisputable. It is worth erature addressing the topic. As a basic principle it noting that these excessive force injuries, when can be stated that hamstring muscle strain injuries seen in a clinical setting, are often more severe and result from an increase in biomechanical load that may involve all three hamstring muscles compared exceeds the tolerance of the hamstring muscle(s). to the typical running sport injury. In understanding the mechanism of hamstring Another example where this mechanism (exces- muscle strain injuries we need to consider factors sive load) may be the predominant mechanism that may increase or decrease biomechanical load for injury is those sports where the muscle and leg on the hamstring muscle. In addition factors that is hyperextended as the athlete attempts a sport- change the load tolerance of the muscle(s) also specifi c movement. Examples can be seen in dance need to be considered. and sports that involve kicking, particularly over- Intuitively in most cases it is diffi cult to see how head kicking (Askling et al., 2007). a change in the biomechanical load to the muscle during athletic performance can be affected. Reduced load tolerance The Olympic motto of faster, higher, stronger, and the demands of modern day sport suggest The most common situation for a hamstring mus- that the demands on the athlete and the muscles cle strain injury occurs when the athlete is sprint- that propel the athlete are more likely to increase ing and/or accelerating. This action is common to over time rather than decrease. Therefore in look- many sports but especially in track running and ing at hamstring muscle strain injury mechanisms in all of the football codes around the world. The with a view to prevention, how factors change the considered mechanism for injury in these cases is load tolerance of the hamstring muscle are prob- predominately a reduction in the load tolerance of ably more important as there is more potential to the hamstring muscle making it more susceptible modify some of these factors. Factors that reduce to the strain injury as opposed to an increase in the load tolerance of the hamstring muscle may biomechanical load. This assertion comes from the render the hamstring muscle more susceptible to observation that most injuries occur randomly in 80 Chapter 6 the act of running, an event that the athlete per- in the pathogenesis of hamstring muscle strain forms constantly and where there is no observable injury. We understand the different frequency of increase in biomechanical load. This leads to the muscle injuries from the results of imaging stud- conclusion that a decreased load tolerance is the ies undertaken in running athletes (Slavotinek most likely explanation. In other words the load- et al., 2002; Connell et al., 2004) where reduced bearing properties of the muscle are altered in such load tolerance is suspected to be a key factor in a manner that the muscle can no longer tolerate injury pathogenesis. a load that it had previously tolerated. This injury At this time little research has been undertaken as event is generally a sudden onset in nature and to why the biceps femoris (long head) is the most generally unpredictable. In one stride the athlete susceptible to muscle stretch injury as a consequence and hamstring muscle, are functioning normally of a reduced ability to resist normal loading forces and suddenly in the next stride the athlete sustains whilst the athlete is sprinting. Important factors that a hamstring injury. may be unique to the biceps femoris muscle include Factors that may be important in reducing the the rate (velocity) and the amount of stretch of the load tolerance properties of the hamstring muscle muscle that occurs in the muscle and tendon, its are often considered to be risk factors for injury. anatomical location and the amount of force (load) These have been discussed in the earlier section. that needs to be dissipated by this muscle. However it can be said that in most cases how In hamstring muscle strain injuries where exces- each of the earlier described risk factors reduces sive force is the considered mechanism it is often the capacity of the hamstring muscle to resist nor- shown, by imaging studies, that more than one mally tolerated forces is unclear and the reasons muscle is injured. At this time it is not clear which for injury are speculative. Similarly the weight- muscle is the predominant muscle injured. ing or importance of each risk factor has not been determined at this time. Musculotendinous junction It should also be remembered that in the sports involving body contact there exists the possibility The most common anatomical location of hamstring that in some cases of hamstring injury, too much muscle injuries is the musculotendinous junction. load on the hamstring muscle is the predominant The reasons for this are unclear but it may represent mechanism of injury rather than a reduced capac- a site of comparative weakness. In the case of the ity of muscle to absorb force. This includes sports biceps femoris muscle, the most commonly injured involving tackling where the athlete tries to force hamstring muscle, injuries appear to be evenly dis- against resistance. In some cases the resistance can tributed in proximal and distal sites as defi ned by result in an excessive force to the hamstring muscle, whether the injury is above or below the insertion of for example, in an American football or rugby scrim- the short head of the biceps femoris muscle into the mage line, or when the athletes’ leg is fi xed (trapped) long head. Again this has been determined princi- whilst they are trying to accelerate or sprint. pally by imaging studies performed on running athletes (Slavotinek et al., 2002; Connell et al., 2004). Predominant hamstring muscle injured Stage of gait cycle

The most common hamstring muscle injured as a For sprinting injuries the muscle is considered sus- consequence of reduced load tolerance of the ham- ceptible to injury in the swing phase of the gait string muscle is the long head of biceps femoris cycle. At this time the hamstring muscle is acting muscle. This is followed in frequency by the semi- eccentrically (developing force whilst elongat- tendinosus and then the semimembranosus mus- ing) to slow the femur and tibia. The typical force cles, respectively. The short head of biceps femoris length curve of the hamstring muscle is shown muscle is infrequently injured and at this current in Figure 6.3. The total amount of force that the time is not considered to be an important muscle hamstring muscles generate is described by the Preventing hamstring injuries 81

200 tolerance of the muscle. The majority of injuries occur during sprinting and/or acceleration and 150 this suggests that reduced load tolerance of the muscle is the most common mechanism of ham- 100 string injury. Reduced load tolerance of the muscle may well be, at least in part, the function of a

Torque (Nm) Torque fatiguing (fatigued) muscle. This fact has implica- 50 tions in the prevention of hamstring injury with the avoidance of muscle fatigue by training the 0 muscle to better tolerate fatigue being the corner- 0 20 40 60 80 100 120 stone of many current hamstring injury preven- Angle (°) tion programs. Other common risk factors are less Figure 6.3. Typical torque length curve of the contracting able to be infl uenced. In effect increasing age, hav- hamstring muscles. The area under the curve represents ing a previous injury, and being a faster player are the total amount of force that the muscle generates. Arrow inherently unchangeable risk factors. signifi es peak torque. However more research needs to be undertaken on the mechanisms of hamstring muscle strain injuries and it is possible that with better under- area under the curve and is considerably more in standing this list may change substantially. Finally, the eccentric (slowing femur through swing) phase it can be stated that at this time it is not known of hamstring action when compared to the con- whether the mechanism of hamstring muscle centric (ground contact and pull-through) phase strain injury is important in the pathogenesis and of the gait cycle. subsequent recovery of the injury and whether It is also considered that the muscle is most vul- this alters the risk for subsequent re-injury. For nerable in the late phase of the swing cycle but example, it is not known whether an overstretch the exact reasons for this as well as the actual bio- or excessive force injury is better or worse in terms mechanical events leading up to and causing the of athlete prognosis than a sprinting/acceleration failure of the muscle are not known at this time. decreased load tolerance injury. As discussed in the risk factors section, fatigue is considered to be an important factor in the pathogenesis of hamstring muscle injury by reducing Identifying risks in the training and the load tolerance that the muscle can withstand competition programs (Mair et al., 1996). It is therefore not surprising that many hamstring muscle strain injuries occur late in a game or training when fatigue is at its Little is known about the differing risks between maximum and in the phase of the gait cycle where the competitive games and training programs. As the most force needs to be generated by the ham- stated earlier hamstring injuries are more likely string muscle, that is, the eccentric swing phase. to occur in the competitive match situation com- The consequence of these factors leads to a rela- pared to training so it is possible that different tive force overload to the hamstring muscle with risks exist for these different situations or more subsequent injury. likely the risks are magnifi ed in the competitive match situation. Some other general non-specifi c observations have been made to identify risks in Take-home message training and competition, but the reasons for The current state of knowledge suggests the fol- these observations are speculative. lowing mechanisms for hamstring muscle strain In many sports there is a predominance of ham- injury: (1) overwhelming force to the muscle, string muscle strain injuries in the early part of (2) overstretch of the muscle, and (3) reduced load the competitive season (Orchard & Seward, 2002). 82 Chapter 6

The reasons for this observation are not known. conditioning is important. Therefore a pre- Pre-season training programs have been primarily season conditioning program requires both aerobic designed to improve the fi tness of the participants. conditioning and anaerobic interval sprint condi- In many cases improving athletes’ fi tness is done tioning in order to attain maximal sport-specifi c in a manner that is not particularly sport specifi c fi tness for the athlete. Current best practice sug- with many training regimens not replicating the gests that if a change from a predominately aerobic specifi c energy demands of the sport. This is espe- program to a predominately anaerobic program is cially true for sports, such as the football codes, considered then this transition should involve a that have extensive aerobic and anaerobic require- gradual, rather than an abrupt, change from one ments with multiple sprinting (maximal efforts) form of training to another. In this way there may being required over an extended time period. An be a reduction in the early season risk of hamstring example of this lack of sport specifi city is to train muscle strain injury. Furthermore once the playing a soccer player by running in 5 km time trials in season has commenced it is now considered that the pre-season. In a competitive game this type of the predominant form of fi tness undertaken at aerobic running is not generally consistent with practice should be in the same manner with respect how the game is played—the running require- to anaerobic/aerobic components, as is needed in ments in a typical soccer game involve recurrent competitive matches. Recent studies on hamstring interval sprinting with maximal and sub-maximal injuries in female elite soccer and elite Australian efforts with each effort generally not lasting more football have demonstrated reduced hamstring than 6 s in time or 50 m in distance. injuries in athletes that undertook a pre-season It is therefore considered that many early season training program that was, in part, undertaken to hamstring muscle strain injuries are the result of attempt to decrease hamstring injury occurrence the failure of the muscle to adapt to the increased (Mjølsnes et al., 2004; Verrall et al., 2005). load (force) that is required to be absorbed when there is a transition from predominately aerobic conditioning that is used in the pre-season train- Prevention measures ing program to the actual requirement of the competitive sport—recurrent maximal anaerobic sprinting efforts. Thus when the competitive There have been very few published studies on matches commence (including the late pre-season the prevention of hamstring muscle strain injury. trial games) more hamstring injuries occur as Similarly, very few of the rehabilitation programs the muscle has not yet adapted to the increased have been validated. As such there is limited scien- load requirements that is specifi c to the running tifi c evidence to assess the results for any preven- demands of competitive sport. An early season tion programs for hamstring muscle strain injuries. predominance of hamstring injuries has been However, analysis of the available evidence dem- demonstrated in some sports including Australian onstrates that some methods for hamstring injury rules football (Orchard & Seward, 2002) and soc- prevention are of probable benefi t whereas others cer (Hawkins & Fuller, 1999). Understanding this demonstrate possible benefi t and fi nally others transition risk factor can assist in developing an have been mentioned as being of benefi t on the effective prevention program. basis of expert opinion. It is also clear that aerobic conditioning is an Improving training specifi city and improving important component in most sports. Recent fatigue resistance were considered to have prob- research suggests that it is even more important able benefi t in preventing hamstring injury. Possible in track sprinting than had been previously recog- benefi cial methods discussed include identifying nized. Most football codes require predominately and modifying at-risk athletes, hamstring mus- interval maximal anaerobic efforts followed by cle strengthening, improving hamstring fl exibility, a limited, or in many cases no, recovery period. and adequate rehabilitation form hamstring injury. It is in the limited recovery period where aerobic Finally, thermal pants and an adequate warm-up Preventing hamstring injuries 83

Table 6.3 Injury prevention Pre-crash Crash Post-crash matrix for hamstring strains: potential measures Athlete Improving training Minimizing fatigue Adequate and comprehensive to prevent injuries. specifi city rehabilitation program Increasing fatigue Identifying size of hamstring resistance injury so adequate rehabilitation program can be instituted Identifying at-risk athletes and implementing targeted prevention programs Hamstring muscle strengthening Improving muscle fl exibility Warm-up Rules/ ––– environment Material Thermal pants – – have been considered benefi cial to preventing ham- Improving fatigue resistance string strain injury and are also discussed. A summary There is evidence that fatigued muscles are able of these methods are presented in the hamstring to absorb less energy than non-fatigued muscles. injury prevention matrix shown in Table 6.3. Therefore by improving the specifi city of training and muscle conditioning it may be possible to pre- Improving training specifi city vent hamstring muscle strain injuries by making the muscle more fatigue resistant and better able At the highest level of participation most athletes to absorb energy loads particularly in the eccentric require an extreme level of fi tness especially in phase of the gait cycle action where the muscle is sports such as the football codes where the ath- most commonly injured. letes can compete for up to 2 h. In many of the pre-season and in season training programs for these football codes there has been an emphasis on Identifying at-risk athletes aerobic conditioning as the predominant training. The principal risk factors for hamstring muscle However the energy requirements of most foot- injury are increasing age of the athlete and the ath- ball codes require the athletes to be able to cope lete having a previous history of hamstring injury. with high-intensity anaerobic interval maximal These risk factors cannot be altered. However iden- or sub-maximal sprinting efforts. As discussed in tifying these athletes in the team group, inform- the mechanisms section, it is in the process of the ing these athletes of their at-risk status, and then intensive anaerobic effort, the sprint, that many targeting prevention programs to these particular hamstring muscle strain injuries occur. athletes is a strategy that may prove worthwhile in Most sports with similar energy requirements preventing hamstring injuries. should consider improving the specifi city of training so that the athletes are better able to cope with Strengthening match day, the principal time of hamstring muscle strain injury, running stressors. Thus “training Increased hamstring muscle strength has long been as the game is played” should prevent hamstring considered to help prevent hamstring injuries, and injuries by improving hamstring muscle condi- recent scientifi c evidence supports this proposi- tioning and developing improved fatigue resist- tion. As the principal role of the hamstring muscles ance. There is evidence to support this proposition is to eccentrically slow the femur and tibia and is (Heidt et al., 2000; Verrall et al., 2005). antagonistic to the quadriceps muscle it is felt that 84 Chapter 6

Table 6.4 Eccentric strength Week Sessions per Sets and repetitions Comments training program (Nordic week hamstring lowers, see 1 1 2 sets, 5 repetitions Adaptation to the exercise. Important Figure 6.4a, b). to start slowly, this is a demanding exercise. Do not do too many sessions, sets or repetitions in the beginning; it could result in excessive muscle soreness. 2 2 2 sets, 6 repetitions Try to hold against with the hamstring muscles as long as possible before falling on the arms. 3 3 3 sets, 6–8 repetitions Increased loading. It is possible to withstand the forward fall longer and perform more sessions, sets and repetitions. 4 3 3 sets, 8–10 repetitions Near full program. 5 or more 3 3 sets, 12–10–8 repetitions Full program. When it is possible to withstand the whole range of motion for 12 repetitions, the load can be increased by adding speed to the starting phase of the motion or by having someone to push on the subjects back (in the height of the shoulder blades) at the starting phase.

strengthening the hamstring muscle may assist in or whether other factors are as important. These improved attenuation of this force thereby decreas- other factors include improving fl exibility, improving the injury risk. Recently, exercises that may be ing fatigue resistance, and improving the functional more specifi c in increasing eccentric hamstring operation of the hamstring muscles. In this man- strength have been studied. An exercise called Nordic ner whenever studies report an increase in strength hamstring lowers has been introduced as a potential of the hamstring muscle as being the mechanism of preventive exercise for hamstring strains (Table 6.4). the intervention effect it is diffi cult to be confi dent This exercise program has been shown to increase that this is actually the case. Although more research the eccentric hamstring strength (measured at 60º/s) is needed, strengthening remains an important by 11% in a period of 10 weeks of training (Árnason method to consider in preventing hamstring injury. et al., 2008). A 4 year study of 17–30 Norwegian and Icelandic elite soccer teams indicated that teams that Flexibility used the Nordic hamstring lowers exercise combined with stretching of short duration during warm-up The role of fl exibility in muscle strain injuries has reduced their risk of hamstring strains by 57% com- not yet been fully elucidated. The presented stud- pared to teams that did not use the program during ies into this area have been poorly performed with the same season (Árnason et al., 2008). The inter- regards to the injury defi nition used and the repro- vention teams also showed a lower incidence of ducibility of the fl exibility measures. At this time hamstring strains than the same teams during the it is not possible to state the boundaries of normal baseline seasons (58% lower rate). and abnormal fl exibility and thus the amount of It has not yet been determined whether strength- fl exibility that places an athlete at risk is not clear. ening prevents hamstring injury solely by increas- Accordingly, it is not clear how to implement pre- ing the eccentric strength of the hamstring muscle vention programs that may change fl exibility. Preventing hamstring injuries 85

(a) (b)

Figure 6.4. Eccentric strength training using Nordic hamstring lowers. Nordic hamstring lowers is a partner exercise. The subject kneels on soft, but fi rm ground. The partner stabilizes the subject’s legs by holding them down at the fl oor. It is important that she holds tight and does not allow any movement. The subject leans forward, keeping his back straight, slight fl exion in hips is allowed. He resists the forward fall with his hamstrings as long as possible and then uses his arms and hands to buffer the landing, going all the way down until the chest touches the ground. Then he uses his arms to push off so she can reach the kneeling position again. Reproduced from Bahr (2004) with permission from the publisher (©Lill-Ann Prøis & Gazette Bok)

Laboratory evidence on animal muscle have dem- and attempts to justify the rationale for each onstrated that muscles have been shown to increase action. An example of a typical rehabilitation pro- force absorption for any given increase in length gram for a sport requiring interval high-intensity (stretch) of the muscle. Thus increasing fl exibil- sprinting is demonstrated in Table 6.6. ity may make the muscle more resistant to stretch There is little scientifi c evidence for the intensity, injury. However, in the study from Norway and duration, and timing for any exercise that is intro- Iceland mentioned earlier, no effect was found from duced in the immediate post-injury period. However fl exibility training alone (Árnason et al., 2008). it is generally accepted that controlled exercise, as opposed to rest, should be introduced early in the Rehabilitation of hamstring injuries rehabilitation period. Histological evidence demon- and the relationship to prevention strates that muscle injury repair involves scar for- of injuries mation at the site of injury. It is considered that the formed scar does not have the same properties as For hamstring muscle strain injuries, in fact for all the pre-existing muscle with respect to load attenu- muscle strain injuries, the rehabilitation program fol- ation making the injured muscle and surrounding lowing injury is an important factor in attempting to muscle area more prone to further injury (re-injury). prevent re-injury. This is due to the observation that By commencing activities early in the post-injury the most important risk factor for hamstring mus- period it is thought that the scar formation at the cle injury is previous injury. Hence many hamstring site of injury will be improved in terms of attaining injuries are actually re-injuries, thereby making the properties that are more like the pre-existing mus- components of the original rehabilitation program cle. This would then result in an increased tolerance important in preventing hamstring (re)injury. of the muscle to load when more strenuous activity Studies of Australian rules football players dem- is recommenced with a subsequent reduced risk for onstrate that this risk for re-injury occurs prin- re-injury. There is some supportive histopathological cipally for the fi rst 8 weeks following an injury. evidence for this proposition. Further evidence for Unfortunately there are very few studies demon- introducing stretches and activities early in the reha- strating the effects of rehabilitation programs on bilitation period comes from studies that examine re-injury risk. Table 6.5 analyzes the components of the length–tension curve of previously injured ath- a typical hamstring injury rehabilitation program letes (Brockett et al., 2004). In effect these demonstrate 86 Chapter 6

Table 6.5 Components of a hamstring muscle strain injury rehabilitation program.

Progression/action Rationale

At injury Remove from fi eld of play Prevent further injury Apply ice and compression Prevent bleeding of injury. Recent evidence from MRI studies of hamstring muscle strain injuries suggests bleeding is not a common outcome of these injuries. If bleeding is demonstrated to be present clinically, usually at day 2 or 3 following injury, by the presence of a bruise, then this generally signifi es a higher grade (more severe) hamstring injury. However despite the lack of evidence for ice application for hamstring injuries it is still recommended that it is performed post-injury. Immediate post-injury period Commence stretching and weight-bearing Aids in the healing of the injury with the aim being an earlier and more successful activities (in terms of a reduction in injury recurrence), return to sport. Commence non-weight-bearing activities (e.g., Prevent athlete deconditioning in the rehabilitation period. cycling, swimming) Introduce anti-infl ammatory medication Overall there is little evidence for this approach and some contention. In support of this it can be considered that the anti-infl ammatories can act as an analgesic and therefore allow an earlier commencement of activities in rehabilitation. It should be stated that some authors consider that anti-infl ammatories impede healing at the injury site and thus increase the re-injury risk in athletes. Post-injury period Stretching and running progression A graduated increase in activities is stated to reduce the risk of overloading the injured muscle, and also allow increasing load tolerance, thereby reducing the risk of subsequent re-injury. Introduction of specifi c sport skill exercises To ensure the athlete is ready for return to play. Commence strengthening Improve the strength of the muscle making the muscle less prone to re-injury as the muscle is able to absorb more force for any given length or tension. There is however little scientifi c evidence to support this proposition and therefore many hamstring rehabilitation programs do not have a formal strengthening component. This component of the rehabilitation program is discussed in more detail in the following section. that the hamstring heals in a shortened position hamstring muscle strain injury of sustaining with a reduction in the angle of the knee where the another strain injury on the same side, with a high hamstring generates maximal force when compared proportion of these re-occurring in the rehabilita- to athletes who have not had a previous hamstring tion and/or the immediate return to sport period. injury (Figure 6.6). This is considered to be a risk In Australian Rules football there is an increased risk for re-injury and it has been suggested that an early for hamstring muscle re-injury for up to 8 weeks introduction of stretching, including eccentrically after the athlete returns to sport. The re-injury risk based stretches, may be important in preventing drops to less than 4% after the athlete has played this shortening. eight matches. In many cases this time period can be 3 months from the original hamstring muscle Current trends in injury management strain injury. with the goal of preventing re-injury Recent trends in this sport have been to manage these injuries more conservatively. These increas- Unfortunately, re-injury following rehabilitation is ingly conservative measures include: very common. In Australian football the re-injury 1. A longer convalescent interval (an increase rate is ~30% (Orchard & Seward, 2002). There in time before the athlete returns to competitive is about a one in three risk of an athlete with a matches) after the athlete sustains an injury. Preventing hamstring injuries 87

Table 6.6 An example of a rehabilitation program used post-hamstring injury in a sport requiring multiple maximal anaerobic efforts with a short duration of recovery (e.g., soccer, Australian football).

Progression Program

Upon injury Ice 20 min every hour; 5 episodes Ice bath optional Elevation Compression bandage Injury plus 1 day Examination Full weight bearing Rest from activities Injury plus 2 days Stretch to point of pain Pain free walking Injury plus 3–5 days Re-examination Stretching Bike, swim, pool running as tolerated Pain free emphasis for all activities on days 0–5 Ultrasound once per day. Gentle massage only when pain free No anti-infl ammatory medication (injection/oral/topical) Return to running (see later) when walking pain free Commence weights and eccentric exercises when pain free stretch (see later) is obtained Running progression Progression upon completion of two to three sessions in each of the following: 1. Pain free walking—jogging 4ϫ500 m 2. Interval running (Jog, slow speed, run) maximum speed 70%—4ϫ500 m, Avoid rapid acceleration. 3. Commence speed running (No rapid acceleration). 80–90% speed—Commence at 5 times of 40 m for 2 sets. Therefore 10 times total with 15 min break between sets. 4. Speed running—no rapid acceleration—80–90% speed—10 times of 40 m for 2 sets. Therefore 20 times total with 15 min break between sets. 5. Deceleration runs. No rapid acceleration—10 times of 40 m—90% effort for 2 sets—deceleration (complete stop) within 20 m decreasing to 10 m. 6. Acceleration runs—5 times of 40 m for 2 sets 7. Acceleration runs—10 times of 40 m for 2 sets—full acceleration from crouched start Stretching progression Progression to next stage when pain free: Passive hamstring stretch—when pain free Active hamstring stretches with physiotherapy supervision (see Figure 6.5a, b) Strength assessment by physiotherapist—if no detectable difference clinically between affected and non- affected side then commencement of eccentric stretching regime—slow Commencement of fast eccentric stretches and closed-chain weights regimen Return to sports-specifi c Return to sports-specifi c training when achieved running and stretching progression PLUS normal training examination. Normal examination parameters include absence of posterior thigh tenderness, pain free resisted hamstring contractions in prone (straight leg and 20º fl exion; internal, neutral and external leg rotation positions) and supine (knee fl exion; full extension and 90º knee fl exion positions) Return to playing when achieved 1 full week of training Rehabilitation continued after return to sport; continues for 8 weeks post return to sport

2. Less aggressive treatment of the hamstring use of strengthening programs in the immediate muscle strain injury in the immediate post-injury post-injury period. period, including less use of anti-inﬂ ammatory 4. Continuing rehabilitation for some time after medication and other controversial strategies such the athlete has returned to sport. as corticosteroid injections. 5. Attempting to prevent signiﬁ cant muscle 3. More emphasis on the introduction of fatigue in the immediate return to sport period stretching, including eccentric based stretches, in with increased use of rest periods and if allowable the immediate post-injury period with a decreased in the sport interchange periods. 88 Chapter 6

(a) (b)

Figure 6.5. Example of eccentric exercise performed during rehabilitation—drop and catch. The athlete is lying on stomach, knee ﬂ exed to 90º. The muscles are relaxed allowing the foot to fall to ground (“the drop”). The foot is prevented from touching the ground (“the catch”) by contracting the hamstring muscles. Initially gravity is used but later in the rehabilitation pathway ankle weights can be added

Thermal pants 70 Expert opinion has suggested that wearing thermal 60 pants to keep the hamstring muscle warm may be 50 useful in hamstring injury prevention, though lit- 40 tle evidence exists to prove their efﬁ cacy. 30

Torque (Nm) Torque 20 Warm-up 10 Inadequate warm-up has long been considered to 0 be a risk factor for injury though little evidence 0 20 40 60 80 100 120 exists for this assertion. It can be stated that warm- Angle (°) up is probably more useful in preparing the athlete Figure 6.6. Hamstring force production in previously for best performance during competition rather injured and healthy hamstring muscles. The previously than being useful for injury prevention. injured hamstring muscle is denoted by large black dots. Note that although the total amount of torque generated is approximately the same as for the uninjured side (white Changing the sport to decrease the dots), the peak force production occurs at decreased knee number of hamstring injuries angle. Effectively the hamstring has healed short. Redrawn with permission from Brockett et al. (2004) Aside from the inconvenience to the athlete and the team, and in professional sport this inconvenience can be considerable and have a signiﬁ cant impact on the playing level and professional remu- The evidence for this more conservative approach neration for the athlete that sustains the injury, has not been validated at this time and it remains in most cases a hamstring muscle strain injury to be seen whether these strategies can prevent has no long-term negative health consequence more hamstring muscle strain reinjuries. for the athlete. These injuries are considered Preventing hamstring injuries 89

Table 6.7 Current trends in implementing hamstring muscle injury prevention program for team sports requiring high-intensity anaerobic interval sprinting and aerobic performance, applicable to sports such as football, soccer, Gaelic football, Australian Rules football, hockey, rugby. The Aussie Rules program.

Progression Rationale

1. Implementing testing procedures that measure Most team sports particularly at the elite playing level measure athletic the performance requirements (high-intensity interval performance in the pre-season to gauge the fi tness of the athlete. Often sprinting) of the sport the athlete focuses his/her training with an emphasis on performing well at this measure. As “training as the game is played” is the goal of pre-season conditioning, with respect to hamstring injury prevention, then using measures of anaerobic interval performance are preferable to aerobic performance. An example of this is the use of the 20 m repeated shuttle run test (multi-stage fi tness testing) rather than the 3 km time trial performance. 2. Implementing specifi c training drills that more closely Improving muscle conditioning and anaerobic performance and obtaining refl ect match day conditions fatigue resistance. 3. Increasing the number of hamstring muscle Increasing energy absorption of hamstring muscle for any given length of stretching regimes whilst muscle is fatigued muscle and improving fatigue resistance. 4. Avoiding exercises that may lower the hamstring to An example of this is the increasing use of closed kinetic chain exercises quadriceps strength ratio for weights training rather than open kinetic chain exercises as these latter exercises are more likely to alter the H:Q ratio. Quadriceps to hamstring strength ratios have been shown to be predictive for hamstring muscle strain injury. Therefore any exercise that may possibly change this ratio should be avoided especially in athletes without previous history of hamstring injury. 5. Avoiding exercises that may change the length– An example of this would be to increase the volume of slow running or cross tension curve of the hamstring muscles in a negative training using stationery cycling in athletes that require their length–tension fashion curves to be maximal, that is, athletes required to sprint at full intensity. Decreasing the length–tension curve of the hamstring muscles may place the athlete at increased injury risk. This is the postulated mechanism for the high rate of injuries in athletes that have had a previous hamstring injury.

part of the game and hence there is little need for may cause a mismatch in hamstring to quadriceps the sports governing bodies to consider rule, or strength, and avoiding exercises that may change other, changes that may help decrease the ham- the length–tension curve of the hamstring mus- string injury rate. cles in a negative fashion. There is some evidence that training based on these principles may reduce Current trends in implementing injury risk signiﬁ cantly (Verrall et al., 2005). hamstring muscle injury prevention (Aussie Rules program) Take-home message

In a rapidly changing fi eld some of the current There is a need for more well-conducted research trends in training athletes for the purpose of into the area of hamstring injury prevention, but hamstring injury prevention, and their rationale there is however enough evidence to make some for their introduction, can be seen in Table 6.7. recommendations that may be useful in ham- This program has been developed based on some string injury prevention. This includes eccentric basic principles related to implementing sports- strengthening exercises, sports-specifi c testing and specifi c testing procedures, specifi c training drills conditioning programs, and appropriate rehabili- that more closely refl ect the requirements of the tation after injury. However, this is a fi eld that is sport, increasing hamstring muscle stretching rapidly changing as more evidence about what whilst muscle is fatigued, avoiding exercises that works (and what does not) emerge. It is important 90 Chapter 6

Orchard, J., Seward, H. (2002) Epidemiology of injuries that the physician, trainer, coach, etc. keep up in the Australian football league 1997–2000. British to date with the latest developments and closely Journal of Sports Medicine 36, 39–44. monitor the athletes in their care. Slavotinek, J.P., Verrall, G.M., Fon, G.T. (2002) Hamstring injury in athletes: the association between MR measurements of the extent of muscle injury and the amount of time lost from competition. AJR American References Journal of Roentgenology 179, 1621–1628. Taylor, D.C., Dalton, J.D., Seaber, A.V., Garrett Jr., W.E. (1993) Experimental muscle strain injury. Early Árnason, Á., Sigurdsson, S.B., Gudmundson, A., Holme, I., functional and structural defi cits and the increased Engebretsen, L., Bahr, R. (2004) Risk factors for injuries risk for reinjury. American Journal of Sports Medicine 21, in soccer. American Journal of Sports Medicine 32, 190–194. 5S–16S. Verrall, G.M., Slavotinek, J.P., Barnes, P.G., Fon, G.T., Árnason, Á., Andersen, T.E., Holme, I., Engebretsen, L., Spriggins, A.J. (2001) Clinical risk factors for hamstring Bahr, R. (2008) Prevention of hamstring strains in elite muscle strain injury: a prospective study with soccer: an intervention study. Scandinavian Journal of correlation of injury by magnetic resonance imaging. Medicine and Science in Sports 18, 40–48. British Journal of Sports Medicine 35, 435–440. Askling, C.M., Tengvar, M., Sartook, S., Thorstensson A. Verrall, G.M., Slavotinek, J.P., Barnes, P.G., Fon, G.T. (2007) Acute fi rst-time hamstring strains during slow- (2003) Diagnostic and prognostic value of clinical speed stretching: clinical, magnetic resonance imaging fi ndings in 83 athletes with posterior thigh injury. and recovery characteristics. American Journal of Sports Comparison of clinical fi ndings with magnetic Medicine 35, 1716–1724. resonance imaging documentation of hamstring muscle Bennell, K., Wajswlner, H., Lew, P., Schall-Riaucour, A., strain. American Journal of Sports Medicine 31, 969–973. Leslie, S., Plant, D., Cirone, J. (1998) Isokinetic Verrall, G.M., Slavotinek, J.P., Barnes, P.G. (2005) strength testing does not predict hamstring injury The effect of sports specifi c training on reducing in Australian rules footballers. British Journal of Sports the incidence of hamstring injuries in professional Medicine 32, 309–314. Australian Rules football players. British Journal of Brockett, C.L., Morgan, D.L., Proske, U. (2004) Predicting Sports Medicine 39, 363–368. hamstring injury in elite athletes. Medicine and Science Verrall, G.M., Slavotinek, J.P., Barnes, P.G., Fon, G.T, in Sports and Exercise 36, 379–387. Esterman, A (2006) Assessment of physical Connell, D.A., Schneider-Kolsky, M.E., Hoving, J.L., examination and magnetic resonance imaging fi ndings Malara, F., Buchbinder, R., Koulouris, G., Burke, F., as predictors for recurrent injury. Journal of Orthopaedic Bass, C. (2004) Longitudinal study comparing and Sports Physical Therapy 36, 225–233. sonographic and MRI assessment of acute and healing hamstring injuries. AJR American Journal of Roentgenology 183, 975–984. Further reading Garrett Jr., W.E. (1996) Muscle strain injuries. American Journal of Sports Medicine 24, S2–S8. Hawkins, R.D., Fuller, C.W. (1999) A prospective Bahr, R. (2004) Preventing sports injuries. In R. Bahr & epidemiological study of injuries in four English S. Mæhlum (eds) Clinical Guide to Sports Injuries, professional football clubs. British Journal of Sports pp. 41–53. Human Kinetics, Champaign. Medicine 33, 196–203. Bahr, R., Holme, I. (2003) Risk factors for sports Heidt Jr., R.S., Sweeterman, L.M., Carlonas, R.L., Traub, J.A., injuries—a methodological approach. British Journal of Tekulve, F.X. (2000) Avoidance of soccer injuries with Sports Medicine 37, 384–392. pre-season conditioning. American Journal of Sports Geraci, M.C. (1998) Rehabilitation of the hip, pelvis Medicine 28, 659–662. and thigh. In W.B. Kibler, S. Herring & J.M. Press (eds) Mair, S., Seaber, A., Glisson, R., Garrett Jr., W.E. (1996) The Functional Rehabilitation of Sports and Musculoskeletal role of fatigue in susceptibility to acute muscle strain Injuries, pp. 216–243. Aspen, Maryland. injury. American Journal of Sports Medicine 24, 137–143. Orchard, J., Best, T.M., Verrall, G.M. (2005) Return to Mjølsnes, R., Arnason, A., Østhagen, T, Bahr, R. (2004) play following muscle strains Clinical Journal of Sports A 10 week randomized trial comparing eccentric vs. Medicine 15, 436–441. concentric hamstring strength in well-trained soccer Petersen, J., Hölmich, P. (2005) Evidence based players. Scandinavian Journal of Medicine and Science in prevention of hamstring injuries in sport. British Sports 14, 31–37. Journal of Sports Medicine 39, 319–323. Chapter 7 Preventing groin injuries Per Hölmich1 and Lorrie Maffey2 and Carolyn Emery3

1Department of Orthopaedic Surgery, Orthopaedic Research Unit, Copenhagen S, Denmark 2Faculty of Kinesiology; Community Health Sciences, Faculty of Medicine, University of Calgary, Calgary, Canada 3Sport Medicine Centre, Faculty of Kinesiology; Community Health Sciences, Faculty of Medicine, University of Calgary, Calgary, Canada

Epidemiology of groin injuries in sports

Groin injuries in sport are common, yet often diffi cult to diagnose and treat. Groin injuries may Abdominal be acute but often become chronic in nature. The Iliopsoas muscle strain muscle strain most common location (Ͼ50%) of groin pain Sports reported in athletes is the adductor muscle ten- hernia Hip joint etiology don region. Acute onset pain in this region is com- Iliopsoas (i.e., labral tear, monly attributable to an adductor longus muscle muscle osteoarthritis, strain impingement) enthesopathy but may also be related to the ili- Stress opsoas and or the abdominal muscles. The dif- fracture Obturator or lateral Adductor femoral cutaneous muscle strain Osteitis pubis/ ferential diagnosis for groin pain in athletes may pubalgia/pubic nerve entrapment include incipient hernia (also known as sports bone stress hernia or athletic hernia), adductor-related groin Figure 7.1. The differential diagnosis for groin pain in pain, abdominal muscle strain, hip joint etiol- athletes is widespread and may include any items listed on ogy (i.e., labral tear, osteoarthritis, impingement), this diagram iliopsoas-related groin pain, fracture, nerve compression (i.e., obturator or lateral femoral cutaneous nerve entrapment), or osteitis pubis (i.e., infl ammation often leading to sclerosis of the pubis sym- and “incipient hernia” are commonly used. These physis) (Figure 7.1). The unspecifi c terms “osteitis refer to a condition of groin pain located to the pubis,” “pubalgia,” and “pubic bone stress” are lower part of the abdomen and to the upper and sometimes used when a pathoanatomic diagno- medial part of the groin region, often radiating to sis cannot be made. Lesions to the lower abdomi- the medial thigh and across the pubic symphysis. nal muscles and other structures associated to the Groin injury is among the top one to sixth inguinal canal can lead to a condition with some most common cited injury in the Olympic sports similarities of a hernia. The terms “sports hernia” of ice hockey, speed skating, soccer, and athletics. Groin injuries account for 3–11% of all injuries in some Olympic sports including ice hockey, speed skating, soccer, swimming, and athletics. Sport- Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing specifi c groin strain injury rates vary in the literature ISBN: 9781405162449 from 0.2 to 5 injuries per 1000 participation hours

91 92 Chapter 7

Table 7.1 Risk of groin injury in different sports. The numbers reported are average estimates based on the sport studies with available data.

Sport Competition Training Rank2 Comments incidence1 incidence1

Team sports Ice hockey 2–5 0.5 2–4 (10%) Prospective data Soccer 4 1 2–4 (10–20%) Prospective data Individual sports Speed skating NA NA 5 (10%) Retrospective data Swimming NA NA NA Retrospective data suggests 25/100 elite swimmers/year experience groin pain Athletics NA NA 4–6 (7–9%) Prospective data

1 Incidence is reported for adult, competitive athletes as the number of injuries per 1000 h of training and competition. 2 Rank indicated the relative rank of this injury type within the sport in question, as well as the proportion as a percentage of the total number of injuries within the sport. NA: Data not available.

or 10–25 injuries per 100 sport participants per is, the percentage of athletes suffering from groin year (Table 7.1). Groin strain injuries have been pain at any given time during their sport careers cited to account for 20% of all muscle strain inju- or following sport retirement. As such, time loss ries in elite levels of soccer and Ͼ40% of muscle may not be the best or only predictor of severity strain injuries in ice hockey, specifi cally. Groin though it is the only indicator of severity in the injuries account for Ͼ10% of all injuries in elite literature. levels of ice hockey, soccer, and athletics. It should be noted that few studies utilized similar general injury or groin strain injury defi nitions and even Key risk factors: how to identify fewer studies actually defi ne groin injury. Future athletes at risk consideration of sport participation exposure when examining injury incidence will facilitate comparisons both between studies in the same Groin injury prevention strategies may be devel- sport and across sports. oped and evaluated if there is a good understand- Typically, severity of injury has been reported ing of the athlete population at risk, and the risk in terms of time loss from sport and has been factors associated with injury for this population. reported for elite levels of ice hockey, soccer, and Groin injury risk factors may be considered intrin- swimming. In ice hockey, the mean number of ses- sic or extrinsic to the athlete (Table 7.2). These sions missed in the National Hockey League due to factors can be further identifi ed as modifi able or a groin injury was reportedly 7–12 sessions (range: non-modifi able. Modifi able risk factors are those 0–180) over two seasons of play. In swimming, the that can potentially be altered to reduce injury mean number of sessions missed due to cases of rates through the implementation of injury pre- groin pain was 11. In soccer, 40% of groin injuries vention strategies. There is evidence that modifi - reportedly result in more than 1 week time loss able risks such as decreased levels of sport-specifi c from soccer and 10% result in more than 1 month training, endurance, strength, and balance do time loss. Of course, many groin injuries become increase the risk of overall injury in sport. Non- chronic and many athletes continue to participate modifi able risk factors are those factors that can- despite pain. At this point in time there is little, if not be altered to reduce injury rates through the any good data on prevalence of groin pain, that implementation of injury prevention strategies but Preventing groin injuries 93

Table 7.2 Internal and external factors for groin injury in different sports. The numbers reported are average estimates based on the studies available.

Risk factor Relative risk1 Evidence2 Comments

Internal risk factors—non-modifi able Previous injury 2–7ϫϩϩIce hockey and soccer ↑ Age 3ϫϩIce hockey evidence clear, confl icting evidence in rugby Gender 1 ϩ Ice hockey ↑ Body Mass Index Greater risk ϩ Rugby Sport specifi city—breast stroke Greater risk ϩ In comparison to other stroke specialists Internal risk factors—modifi able ↓ Amount of sport-specifi c training 3ϫϩIce hockey in the pre-season (Ͻ18 sessions) ↓ Hip range of motion 1.1ϫϩEvidence in soccer, confl icting evidence in ice hockey ↓ Hip adduction strength 1 ϩ Confl icting evidence ↑ Hip abduction strength Greater risk ϩ Rugby ↓ Hip adduction: abduction strength Greater risk if ϩ Ice hockey ratio ratio Ͻ95% Delayed onset transverse abdominal Greater risk ϩ Australian Rules football muscle recruitment

However, another study in Australian Rules injury in breaststroke specialists, followed by Football demonstrated that players under 18 years individual medley and fi nally those specializing of age were at greater than two times the risk of in a combination of non-breaststroke/individual groin strain injury than the more veteran players. medley. This is not surprising given the unique Increasing age and sport experience as risk factors eccentric adductor muscle activity and abduction for groin injury may be rationalized by the idea ROM required in breast stroke kick compared to that the body’s collagen tissue changes in its nature that in other strokes. with advancing age and therefore it may not be as potentially adaptable to respond to quick force Modifi able intrinsic risk factors: range changes or recover from fatigue. Additionally, it has of motion been shown that specifi c muscle strength decreases with advancing age which may put these muscles Confl icting evidence exists for the role of more at risk for injury. There is consistency in the decreased hip abduction ROM as a risk factor for literature to support increased age as a risk factor for groin strain injury. In one study, a protective effect muscle strains in the hamstring and calf muscles. (10% risk reduction) related to greater hip abduc- Decreased age and sport experience as a risk factor tion and extension (i.e., players identifi ed as being for groin injury in Australian Rules football players in the top 1/3 of players based on fl exibility) in may be secondary to the study’s defi nition of groin soccer players has been identifi ed. However, there injury that included muscular and unspecifi ed has been no evidence of hip abduction ROM as a groin injuries such as osteitis pubis, differing from risk factor for groin strain injury in other sports. other studies that did not include osteitis pubis. A possible explanation between decreased ROM In addition, studies fi nding an increased risk with of the hip (as well as or in addition to decreased increasing age did not include players under age 18 ROM of the lumbar spine and or pelvis) and groin and musculoskeletal immaturity may have played a injury may be that decreased ROM of the hip role in the increased risk in junior Australian foot- joints might lead to a change in the biomechanics ball players. related to sprinting, skating, tackling, kicking, and jumping. This could in turn lead to an increase of Gender the load on the related muscles and tendons. An example could be decreased internal rotation of While there is a paucity of literature examining the hip joint leading to a need for changing the groin injury specifi cally in female sport, gender axis of rotation when kicking a ball or tackling. has not been identifi ed as a risk factor for groin This would increase the load on the oblique mus- strain injury. In varsity level ice hockey, gender cles of the lower abdomen and thereby putting was not found to be a risk factor for all injury or more stress on the conjoint tendon (i.e., where the groin strain injury specifi cally. Gender differences tendons of the transverse abdominal muscle and have more commonly been reported for ligament the internal oblique muscle join and insert into sprain injuries. the pubic tubercle). This could result in an infl ammatory response and/or degeneration of the ten- Body composition don leading to pain by itself or to a strain, a tear, or an avulsion. Increased body mass index has been identifi ed as a An explanation for the confl icting evidence risk factor for groin injury in rugby players but not regarding the connection between decreased hip in any Olympic sports. ROM and groin injury is that there is evidence that most muscle injuries occur during eccentric Sport specifi city contractions within the normal range of joint motion and not the end of range and that stretch- In swimmers, specifi cally, stroke specifi city is a risk ing is not signifi cantly associated with a reduc- for groin strain injury with a greater risk of groin tion in total injuries. This ongoing debate over Preventing groin injuries 95

ROM or fl exibility may have to do more with the Training background inconsistent methods of testing and defi nitions Decreased levels of pre-season sport-specifi c train- in the literature. Additionally, there is a growing ing was clearly a risk factor for groin strain injury in body of evidence that is pointing toward stretch- the National Hockey League, with players training ing being functional to the activity demands of the less than 18 sport-specifi c sessions in the pre-season sport as well as the individual body concerns of the demonstrating a threefold increase risk (Emery & athlete. The contradiction in the evidence regard- Meeuwisse, 2001). An increase in pre-season sporting the role of stretching in sport performance specifi c training and a subsequent decrease in groin and injury prevention may be explained by differ- injury may be supported by eccentric training of ences between sport activities. In sports involving the thigh muscles as well as abdominal supporting “explosive” type skills, stretching may result in an muscular training. Pre-season sport-specifi c training increased capacity for the tendon to absorb energy may allow for further contraction and function- and thereby be a prophylactic measure for injury specifi c recruitment of these muscles which might prevention. The demands on different players (i.e., allow for their more effective utilization and less position of play) within the same sport may also onset of fatigue as the season progresses. Fatigue differ, resulting in potentially divergent effects has been noted in the literature to be a contribut- from the same fl exibility program. The evidence- ing factor for muscle injury. based debate regarding muscle fl exibility and its role in injury prevention continues. A recent study of community level Australian football play- Muscle strength and function ers suggested that decreased quadriceps fl exibility was an independent predictor of hamstring injury With respect to hip muscle strength, while there in this group of athletes. This fi nding further fuels was no evidence that peak isometric adduc- the discussion that it may not be adductor muscle tor strength was a risk factor for groin injury in length that is the important factor in groin injury ice hockey, the adductor to abductor isometric prevention but rather the muscle length of its syn- strength ratio might be a risk factor for groin strain ergistic and opposing muscles such as the abduc- injury in ice hockey. In one study, the pre-season tor and hip fl exor muscles. Additionally, when adductor strength was 18% less than the abductor traumatic osteitis pubis is considered as a poten- strength in those players sustaining a subsequent tial source of groin pain, a reduction hip range of groin injury, compared to those uninjured dur- motion (ROM) is demonstrated in athletes with ing the season (Tyler et al., 2002). In rugby players chronic current and recovered groin injury. As there has been some support for non-dominant insertional tendinopathy and osteitis pubis are limb peak abductor torque and peak torque later often clinically diffi cult to diagnostically sepa- in abduction ROM with isokinetic testing being rate (and may even be the same injury where the predictive for groin strain injury (Cusi et al., 2001). changes in the pubic symphysis are a refl ection of It is hypothesized that the mechanism of injury the increased stress across the joint because of the associated with groin injuries in ice hockey players disturbed pelvic stability combined with the strain is the eccentric force of the adductors attempting imposed by the sport itself), it may be that some to decelerate the leg during a stride. A systematic studies on groin strain injury are including ath- review examining muscle strength as a risk fac- letes with a past injury of osteitis pubis as study tor for acute muscle strain, also found decreased participants. Past injury has already been demon- muscle strength and/or muscle ratios to be predic- strated to be a risk factor for groin strain injury tive of strain injury, consistent with the fi ndings and this could be confused with the role of hip related to groin strain injury. It may be that the fl exibility as a risk factor for groin strain injury. adductor strength (i.e., concentric and eccentric) Future work in the area of fl exibility may shed throughout its length as well as the adductor to new light on its importance with regard to injury abductor strength ratio are important factors for prevention. injury prevention. 96 Chapter 7

There is also evidence that the onset of transver- training and abdominal muscle recruitment. sus abdominal muscle recruitment activity (EMG) Inconsistent evidence exists regarding muscle is delayed during an active straight leg raise while strength as a risk factor for groin injury. Arguably, no differences occurred in the other abdominal however, there is some evidence that hip adduc- muscles in Australian Rules Football players with tor:abductor strength ratio may be of importance. long-standing groin pain versus controls suggest- Additionally there is evidence that there are non- ing a possible associated risk. A strength imbalance modifi able risk factors that cannot be altered to between the propulsive muscles and the stabilizing reduce injury rates through the implementation muscles of the hip and pelvis has been proposed of injury prevention strategies such as age or sport as a mechanism for adductor strains in athletes. experience, gender, sport-specifi c movement (i.e., A large percentage of groin pain may actually be breast stroke in swimming), and previous injury. due to inability to properly load transfer from An annual musculoskeletal preparticipation the legs and or torso to the pelvis. Restoring load examination is often done by physiotherapists transferability by restoration of the stabilizing role working with athletic teams to anticipate and pre- of the pelvis by abdominal contraction may be clude physiological and biomechanical problems important in athletic injury management and pos- for athletes prior to the commencement of a sport sibly injury prevention. There is some support for season activities. As such, the ultimate goal of such “core stability” interventions targeting abdominals a preparticipation examination is injury preven- and gluteals in reducing the risk of hamstring and tion. Such a comprehensive examination should groin injury in rugby players but further research identify both the sport-specifi c biomechanical and is required to support these fi ndings. Such fi ndings physiological requirements for training and com- lead to inquiry regarding the role of the muscles petition, as well as when there are possible biome- of the torso (i.e., transverse abdominus, obliques, chanical and physiological defi cits that might be a diaphragm, multifi dus, pelvic fl oor) in stabilizing precursor to injury. Preparticipation examinations the pelvis such that the abductors and adductors consistently include athlete questionnaires includ- can work explosively and not get strained. Perhaps ing questions that might identify an increased risk it is the balance of all the torso muscles that is a for groin injury such as previous injury, levels of critical factor in groin injury. It may be that the pre-season sport-specifi c training, age or sport adductor strength (i.e., concentric and eccentric) experience, gender, and sport-specifi c movements throughout its length, with a balanced and strong (i.e., swimming stroke) (Table 7.3). In addition, torso, may be important for injury prevention. standard neuro-musculoskeletal examinations and Risk factors beyond the groin region alone, some form of functional testing are components including torso musculature, require further of this preparticipation examination. examination. The role of load transfer and torso The standard neuro-musculoskeletal examination stabilizing muscles, eccentric isokinetic strength which tests for strength in the form of isometric, including strength ratios of the adductors to abduc- concentric, and/or eccentric testing contribute to tor muscles, and muscle length of the adductors the identifi cation of such strength ratios (i.e., hip and opposing muscle groups (i.e., abductor and adductor:abductor muscle strength ratio which is hip fl exor muscles) require further consideration. a potential risk factor for groin injury). The standard neuro-musculoskeletal examination should Take-home message: how to identify also include a neurological examination, active athletes at risk and passive ROM testing (decreased hip ROM is another potential risk factor for groin injury), There is evidence that the risk factors for groin articular testing in the form of joint glides, mus- injury that can potentially be altered to reduce cle recruitment testing especially around the torso injury rates through the implementation of injury and pelvis (defi cits here may lead to an increased prevention strategies are decreased hip abduction risk for groin injury), static and dynamic pos- ROM, decreased levels of pre-season sport-specifi c tural and balance investigations, and appropriate Preventing groin injuries 97

Table 7.3 Preparticipation examination: identifying risks for groin injury.

Identiﬁ ed risk for groin injury Preparticipation examination: Preparticipation examination objective Subjective questionnaire examination (speciﬁ c test)

Previous injury X Age or sport experience X Gender X Sport-specifi c movement X Decreased levels of pre-season X sport-specifi c training Decreased hip abduction range Joint ROM: of motion • active • passive Abdominal muscle recruitment Modifi ed double straight-leg lowering test Flexor endurance test Real time ultrasound testing EMG testing Observational scoring Hip muscle strength Muscle strength tests: • isometric (manual muscle testing) • concentric (isokinetic testing) • eccentric (isokinetic testing)

functional tests. Functional performance tests for certainty. Groin injury often has the characteris- the sport in question are recommended for inclu- tics of an overuse injury and the exact moment sion in a preparticipation examination. It is sug- of injury (the inciting event) can be hard to gested that not only the clinical test outcome be establish. scored (i.e., side lunge repetitions) but also the The typical history presented by the athlete with form and effi ciency of the underlying functional a groin injury comes in two versions: (1) 40% have movement involved in the test should be rated. For experienced an acute painful incident during train- example, it is not only important to take note of ing or competition or (2) 60% present with a grad- the weight that an athlete can load with during a ually developing pain in the groin region often one-legged bench side step up test but how the ath- typical of an overuse injury. The acute strain usu- lete’s body was aligned during the test. As few vali- ally involves one or more muscles. In most cases, dated scoring systems exist the examiner is advised the lesion is in the musculotendenious junction, to develop scoring methodologies and to submit but in some cases the tendon itself or the entheses this scoring method to future research scrutiny. where the tendon inserts into the bone is the site Upon recognition of potentially modifi able risk of the injury. These injuries happen during force- factors by the physiotherapist, sport-specifi c injury ful action and the athletes are usually not in doubt prevention strategies designed to reduce such risks that something happened: It hurts, the function of can be implemented (Table 7.4 and Boxes 7.1–7.3). the limb is affected and sometimes a discoloration of the skin is immediate. In most cases, the athlete will have to stop the activity and leave the fi eld. Injury mechanisms In some cases the athlete describes a snapping feeling in the groin and sometimes even accompanied Acute versus chronic injury by a sound. If not attended to appropriately, these injuries might develop into a more long-standing The injury mechanism associated with groin and sometimes chronic injury. The other typi- injuries is in many cases diffi cult to identify with cal history is when the athlete gradually realize, 98 Chapter 7

Table 7.4 Injury prevention matrix for groin injuries: potential measures to prevent injuries.

Pre-injury Injury Post-injury

Athlete Preparticipation examination Training status Treatment (Table 7.3) Falling/tackling/checking Rehabilitation Neuromuscular balance: techniques 1. Hip range of motion Safe technique and Restoration of neuromuscular 2. Hip muscle strength biomechanics function 3. “Core”/trunk recruitment Full rehabilitation from previous injuries Pre-season sport specifi c training Ice or fi eld friction Surroundings Playing rules Playing surfaces (ice, fi eld) in good Emergency medical coverage shape, that is, no holes in fi eld or ice Diagnosing expertise Rehabilitation team (physiotherapy, athletic therapy) Equipment Shoe friction and torsional Groin pressure wraps or First-aid equipment resistance with the playing surface tension shorts Ice Appropriate boot and blade on skate to support the ankle

Box 7.1 Stretching program for the hip muscles

#1. Stretch for hip fl exors #2. Stretch for hip adductors Ensure that the pelvic fl oor, deep transversus abdominus and Ensure that the pelvic fl oor, deep transversus abdominus, and deep multifi dus muscles are recruited while the athlete is quietly deep multifi dus muscles are recruited while the athlete is quietly abdominal breathing. This will help to keep the back in the required abdominal breathing. This will help to keep the back in the required neutral position (not lordotic or kyphotic). While kneeling on the right neutral position (not lordotic or kyphotic or side bent into side knee and with the left hip and knee at a 90º angle and the foot fl at fl exion). With equal weight on each foot, stand with the feet apart on the fl oor (not allowing the medial arch of the foot to collapse), in abduction (slightly wider than the shoulder width if your range translate the pelvis forward thereby allowing the right hip to extend of motion allows for this). Flex the right knee and shift more weight and stretching the right hip fl exors. Maintain this hold for 5–10 slow onto the right leg while you keep the left hip and knee in neutral and gentle breaths. Do not force the movement or move into or fl exion and extension thereby allowing the left hip to further abduct through pain with this movement. Repeat 2–4 times each leg. and stretching the left hip adductors. Maintain this hold for 5–10 Common errors: the low back sags into a lordosis, the left knee slow and gentle breaths. Do not force the movement or move into and leg rotates inward, the left foot medial arch collapses, loss or through pain with this movement. Repeat 2–4 times of the recruitment of the pelvic fl oor and deep transversus each side. abdominus resulting in over activity of the more superfi cial Common errors: the low back sags into a lordosis and or side abdominal muscles as well as breath holding. fl exion, the right or left knee and leg rotates inward, the right

(Continued) Preventing groin injuries 99

Box 7.1 (Continued) or left foot medial arch collapses, left knee and hip fl exes, loss Common errors: the low back sags into a lordosis and or of the recruitment of the pelvic fl oor and deep transversus side fl exion, the left knee and leg rotates inward, loss of the abdominus resulting in over activity of the more superfi cial recruitment of the pelvic fl oor and deep transversus abdominus abdominal muscles as well as breath holding. resulting in over activity of the more superfi cial abdominal #3. Stretch for hip adductors/extensors muscles as well as breath holding. Ensure that the pelvic fl oor, deep transversus abdominus and deep multifi dus muscles are recruited while the athlete is quietly abdominal breathing. This will help to keep the back in the required neutral position (not lordotic or kyphotic or side bent into side fl exion). With the right hip in abduction and fl exion and the right knee in fl exion (like the crossed leg sitting position for the right leg) let the left hip go into full extension with the knee extended as well. Shift your weight toward the right leg and each hand thereby allowing the left hip to further extend and stretching the left hip fl exors and adductors. Maintain this hold for 5–10 slow and gentle breaths. Do not force the movement or move into or through pain with this movement. Repeat two to four times each side.

Box 7.2 Exercises for restoring the recruitment of the torso muscles as well as the strengthening abductor and adductor muscles

Isometric contraction of adductors (a) without and (b) with torso (b) Ensure that the pelvic fl oor, deep transversus abdominus movement and deep multifi dus muscles are recruited while the athlete is (a) Ensure that the pelvic fl oor, deep transversus abdominus quietly abdominal breathing. This will help to keep the back in and deep multifi dus muscles are recruited while the athlete is the required neutral position (not lordotic or kyphotic or side quietly abdominal breathing. This will help to keep the back in bent into side fl exion). With the both knees fl exed, squeeze a the required neutral position (not lordotic or kyphotic or side soccer ball between your knees. bent into side fl exion). With the both knees extended, squeeze Cross your hands in front of your chest and contract your a soccer ball between your ankles and then fl ex both hips to oblique and rectus abdominus thereby raising your torso from approximately 30º. Maintain this hold for 5–10 slow and gentle the fl oor approximately 4 inches. Ensure that your head and breaths. Do not force the movement or move into or through neck stay in line with your thorax. Then fl ex both hips up toward pain with this movement. Repeat 5–20 times. your chest. Maintain this hold for 5–10 slow and gentle breaths. Common errors: the low back lordosis, the legs rotate inward Do not force the movement or move into or through pain with (medially), the hands counter push into the fl oor, the head counter this movement. Repeat 5–20 times. pushes into the fl oor, loss of the recruitment of the pelvic fl oor Common errors: the low back lordosis initially then kyphosis and deep transversus abdominus resulting in over activity of the as the low back counter pushes into the fl oor, the legs rotate more superfi cial abdominal muscles as well as breath holding. inward (medially), the head and neck shear forward from the alignment of the thorax (lower neck fl exion and upper neck extension), gritting of the teeth, loss of the recruitment of the pelvic fl oor, and deep transversus abdominus resulting in over activity of the more superfi cial abdominal muscles as well as breath holding.

(Continued) 100 Chapter 7

Box 7.2 (Continued)

abducts, the arms counter balance by fl exing or abducting, loss of the medial arch of the left foot, dorsi or plantar fl exion and eversion of the right foot, loss of the recruitment of the pelvic fl oor and deep transversus abdominus resulting in over activity of the more superfi cial abdominal muscles as well as breath holding.

Standing with a stable pelvis, that is, good torso control using Standing with a stable pelvis, that is, good torso control using tubing or cables and perform concentric abduction or eccentric tubing or cables and perform concentric adduction or eccentric adduction abduction Ensure that the pelvic fl oor, deep transversus abdominus and Ensure that the pelvic fl oor, deep transversus abdominus and deep multifi dus muscles are recruited while the athlete is quietly deep multifi dus muscles are recruited while the athlete is quietly abdominal breathing. This will help to keep the back and the abdominal breathing. This will help to keep the back and the rest rest of the spine in the required neutral position (not lordotic or of the spine in the required neutral position (not lordotic or kyphotic kyphotic or side bent into side fl exion). With the both hips in a or side bent into side fl exion). With the right hip in a neutral neutral posture, both knees extended and the tubing around posture and the left hip in 15º abduction, both knees extended the right ankle, abduct the right leg to 15º while maintaining the and the tubing around the left ankle, adduct the left leg to neutral spine posture and the left leg posture as well as maintaining an abduction/adduction posture while maintaining the spine posture elevated medial arch of the left foot. Maintain this hold for 5–10 and the right leg posture as well as maintaining an elevated medial slow and gentle breaths. Slowly return back to the start position arch of the right foot. Maintain this hold for 5–10 slow and gentle (both hips in a neutral posture). Do not force the movement or breaths. Slowly return back to the start position. Do not force move into or through pain with this movement. Repeat 5–20 the movement or move into or through pain with this movement. times each side. Repeat 5–20 times each side. Common errors: the low back lordosis, thoracic kyphosis, chin Common errors: the low back lordosis, thoracic kyphosis, chin poked forward head and neck posture, the left leg rotate inward poked forward head and neck posture, the left leg rotate inward (medially), the right leg rotates outward (laterally) and fl exes as it (medially) and fl exes as it adducts, the right leg rotates outward

(Continued) Preventing groin injuries 101

Box 7.2 (Continued)

(laterally), the arms counter balance by fl exing or abducting, loss transversus abdominus resulting in over activity of the more of the medial arch of the right foot, dorsi or plantar fl exion and superfi cial abdominal muscles as well as breath holding. inversion of the left foot, loss of the recruitment of the pelvic fl oor and deep transversus abdominus resulting in over activity of the more superfi cial abdominal muscles as well as breath holding.

Standing with a stable pelvis, that is, good torso control using tubing or cables and perform concentric extension Ensure that the pelvic ﬂ oor, deep transversus abdominus and deep multiﬁ dus muscles are recruited while the athlete is quietly

Standing with a stable pelvis, that is, good torso control using tubing or cables and perform concentric fl exion Ensure that the pelvic fl oor, deep transversus abdominus and deep multifi dus muscles are recruited while the athlete is quietly abdominal breathing. This will help to keep the back and the rest of the spine in the required neutral position (not lordotic or kyphotic or side bent into side fl exion). With the hips in a neutral posture, both knees fl exed approximately 15º and the tubing around the left ankle, fl ex the left hip to approximately 15º while maintaining the spine posture and the right leg posture as well as maintaining an elevated medial arch of the right foot. Maintain this hold for 5–10 slow and gentle breaths. Slowly return back to the start position. Do not force the movement or move into or through pain with this movement. Repeat 5–20 times each side. Common errors: the low back lordosis, thoracic kyphosis, chin poked forward head and neck posture, the left leg rotate inward (medially) and adducts as it fl exes, angle of knee fl exion changes in one or both knees, the right leg rotates outward (laterally), the arms counter balance by fl exing or abducting, loss of the medial arch of the right foot, dorsi or plantar fl exion and inversion of the left foot, loss of the recruitment of the pelvic fl oor and deep

(Continued) 102 Chapter 7

Box 7.2 (Continued)

abdominal breathing. This will help to keep the back and the Common errors: the low back lordosis, thoracic kyphosis, chin rest of the spine in the required neutral position (not lordotic or poked forward head and neck posture, the right leg rotate kyphotic or side bent into side fl exion). With the hips in a neutral inward (medially) and adducts or abducts as it extends, angle posture, both knees fl exed approximately 15º and the tubing of knee fl exion changes in one or both knees, the right leg around the right ankle, extend the right hip to approximately rotates outward (laterally), the arms counter balance by fl exing or 5º while maintaining the spine posture and the left leg posture abducting, loss of the medial arch of the left foot, dorsi or plantar as well as maintaining an elevated medial arch of the left foot. fl exion and inversion of the right foot, loss of the recruitment of Maintain this hold for 5–10 slow and gentle breaths. Slowly the pelvic fl oor and deep transversus abdominus resulting in return back to the start position. Do not force the movement over activity of the more superfi cial abdominal muscles as well or move into or through pain with this movement. Repeat 5–20 as breath holding. times each side.

Box 7.3 Progression of exercises for restoring the recruitment of the torso muscles as well as the strength of the abductor muscles and the adductor muscles: (a) Speed of exercise: (i) Slow (ii) Medium (iii) Fast; (b) ROM: (i) Inner range of motion (ROM) (ii) Mid to Outer ROM; (c) Load/resistance: (i) Low load (ii) Moderate (iii) High load; (d) Base of support: (i) Stable (ii) Unstable (See #1 and #2); (e) Functional speciﬁ c positions (See #3, #4, #5)

#1. Standing with a unstable pelvis with good torso control using tubing and performing concentric abduction or eccentric adduction Ensure that the pelvic fl oor, deep transversus abdominus and deep multifi dus muscles are recruited while the athlete is quietly abdominal breathing. This will help to keep the back and the rest of the spine in the required neutral position (not lordotic or kyphotic or side bent into side fl exion). With the both hips in a neutral posture, both knees extended and the tubing around the right ankle, abduct the right leg to 15º while maintaining the spine posture and the left leg posture as well as maintaining an elevated medial arch of the left foot. Maintain this hold for 5–10 slow and gentle breaths. Slowly return back to the start position (both hips in a neutral posture). Do not force the movement or move into or through pain with this movement. Repeat 5–20 times each side. Common errors: the low back lordosis, thoracic kyphosis, chin poked forward head and neck posture, the left leg rotate inward (medially), the right leg rotates outward (laterally) and fl exes as it abducts, the arms counter balance by fl exing or abducting, loss of the medial arch of the left foot, dorsi or plantar fl exion and eversion of the right foot, plantar fl exion and eversion of the left foot, loss of the recruitment of the pelvic fl oor and deep transversus abdominus resulting in over activity of the more superfi cial abdominal muscles as well as breath holding.

(Continued) Preventing groin injuries 103

Box 7.3 (Continued) #2. Standing with a unstable pelvis with good torso control #3. Functional position: Isometric adduction with or without using tubing and performing concentric adduction or eccentric superimposed squats on the leg abduction Ensure that the pelvic fl oor, deep transversus abdominus and Ensure that the pelvic fl oor, deep transversus abdominus and deep multifi dus muscles are recruited while the athlete is deep multifi dus muscles are recruited while the athlete is quietly abdominal breathing. This will help to keep the back quietly abdominal breathing. This will help to keep the back and the rest of the spine in the required neutral position (not and the rest of the spine in the required neutral position (not lordotic or kyphotic or side bent into side fl exion). Arms behind lordotic or kyphotic or side bent into side fl exion). With the your back resting lightly on the back. With the hips and knees right hip in a neutral posture and the left hip in 15º abduction, fl exed approximately 20º squeeze a soccer ball between your both knees extended and the tubing around the left ankle, knees as well as maintaining an elevated medial arch of the adduct the left leg to neutral abduction/adduction posture foot. Maintain this hold for 5–10 slow and gentle breaths. while maintaining the spine posture and the right leg posture Slowly return back to the start position. Note this can be made as well as maintaining an elevated medial arch of the right foot. more diffi cult by maintaining this position as you do a deeper Maintain this hold for 5–10 slow and gentle breaths. Slowly squat on your leg. Do not force the movement or move into return back to the start position. Do not force the movement or through pain with this movement. Repeat 5–20 times or move into or through pain with this movement. Repeat 5–20 each side. times each side. Common errors: the low back lordosis and side fl exion with Common errors: the low back lordosis, thoracic kyphosis, or without rotation, thoracic kyphosis, chin poked forward chin poked forward head and neck posture, the left leg rotate head and neck posture, the left leg rotate inward (medially) inward (medially) and fl exes as it adducts, the right leg rotates and adducts, right leg abducts and laterally rotates, the arms outward (laterally), the arms counter balance by fl exing or lose their position (often extend off the back), loss of the abducting, loss of the medial arch of the right foot, plantar medial arch of the left foot, dorsi or plantar fl exion and inversion fl exion and eversion of the right foot, dorsi or plantar fl exion of the right foot, loss of the recruitment of the pelvic fl oor and inversion of the left foot, loss of the recruitment of the and deep transversus abdominus resulting in over activity pelvic fl oor and deep transversus abdominus resulting in over of the more superfi cial abdominal muscles as well as breath activity of the more superfi cial abdominal muscles as well as holding. breath holding.

(Continued) 104 Chapter 7

Box 7.3 (Continued)

#4. Functional position: simulated running position note #5. Functional position: skating side to side jumps—note the athlete is to move between positions in photo (a) and (b) the athlete is to move between positions in photo (a) and (b) repetitively and at various speeds and with various limb ROM repetitively and at various speeds and with various limb ROM Ensure that the pelvic fl oor, deep transversus abdominus and Ensure that the pelvic fl oor, deep transversus abdominus and deep multifi dus muscles are recruited while the athlete is quietly deep multifi dus muscles are recruited while the athlete is quietly abdominal breathing. This will help to keep the back and the abdominal breathing. This will help to keep the back and the rest of the spine in the required neutral position (not lordotic rest of the spine in the required neutral position (not lordotic or or kyphotic or side bent into side fl exion). With the hips fl exed kyphotic or side bent into side fl exion). Arms behind your back approximately 20º and the right knee fl exed approximately gentle resting on the low back. With the left hip in a neutral 20º and the left knee fl exed approximately 80º, extend and posture and the left knee in approximately 20º fl exion as well straighten your right knee while maintaining an elevated medial as the right hip abducted approximately 30º and the right knee arch of the right foot. Note this can be made more diffi cult extended, adduct the right leg to neutral and fl ex the right knee by deeper squatting on your right leg as well as alternately approximately 20º while maintaining the spine posture and while swinging your arms as if you were running or skating. Do not the left leg abducts approximately 30º and the left knee extends. force the movement or move into or through pain with this Repeat for the other leg. All the while maintaining an elevated movement. Repeat for 30 s to 2 min each side. medial arch for each foot. Repeat for 30 s to 2 min. Do not force Common errors: the low back lordosis and side fl exion with or the movement or move into or through pain with this without rotation, thoracic kyphosis, chin poked forward head and movement. neck posture, the right leg rotate inward (medially) and adducts, Common errors: the low back lordosis, thoracic kyphosis, chin- left leg abducts and laterally rotates, the arms lose their position poked forward head and neck posture, loss of the leg posturing and coordination with the leg movement, loss of the medial especially inward (medially) rotation of the leg that is in neutral arch of the right foot, dorsi or plantar fl exion and inversion of abduction–adduction, the arms counter balance by fl exing the left foot, loss of the recruitment of the pelvic fl oor and deep or abducting, loss of the medial arch of the feet, loss of the transversus abdominus resulting in over activity of the more recruitment of the pelvic fl oor and deep transversus abdominus superfi cial abdominal muscles as well as breath holding. resulting in over activity of the more superfi cial abdominal muscles as well as breath holding.

that the groin is getting increasingly sore after will recur during the sport as fatigue occurs. If the exercise and becomes an increasing problem even athlete does not get appropriate treatment and during the sports activity. The symptoms are instead continues to participate in the sport, the those of a typical overuse pattern. In the begin- pain-free periods will become shorter and ﬁ nally ning, there is only pain after activity with stiff- all sport activity will cause pain, and even activi- ness of the muscle group and a decreased ROM ties of daily living might be a problem. Frequently, of the hip joint, developing to pain in the groin there is no recollection of a single incident causing at the commencement of sport activity. The pain the pain, but often an increase or change in activ- will often disappear as the athlete warms up, but ity level, technique or likewise has happened. This Preventing groin injuries 105

Proximal adductor muscle group at risk here as left leg is Figure 7.2. The groin muscles can be forcefully in adduction, external rotation loaded from external and internal forces such as and extension. a soccer/football/rugby player in a sliding tackle

same pattern can be seen in athletes returning to in some amount of abduction which is the posi- sport after an initial acute groin injury without tion where this muscle is the weakest and as such receiving appropriate and/or suffi cient treatment more prone to sustain an injury) (Figure 7.2). This and rehabilitation. could be a sudden resistance of an opponent’s foot in an attempt to reach a ball or a sliding tackle Considering mechanism by structure in soccer or the eccentric force of the adductor injured muscles attempting to decelerate the leg during a stride in ice hockey. In many cases some degree of The three most commonly mentioned structures hip joint rotation is involved. It can also happen involved in groin injury in the literature are the in a forceful concentric adduction contraction for adductor muscles (usually adductor longus), the instance in soccer during a kick after a ball in the iliopsoas muscle, and the abdominal muscles. air or as the result of a direct blunt trauma from Decreased ROM of the hip joints, dysfunction contact with an opponent. of the sacroiliac joints, sacrotuberal ligaments, The iliopsoas muscle, being a very important and and low back are often seen concomitant to the strong hip fl exor, can be acutely strained if a force- muscle-related groin injuries. Their role in the ful hip fl exion is interrupted suddenly. This could both risk factors and a mechanism of groin injury happen when the player is tackled in the moment is not clear (see Section “Key risk factors: how to of a forceful hip fl exion during running, skating, identify athletes at risk”). jumping, or kicking (Figure 7.3) or when by mis- When the adductor muscles are acutely strained take kicking into the ground instead of the ball. it is often during an eccentric contraction (e.g., in It can also be injured during an eccentric contrac- a forced abduction, most likely when the limb is tion as when the thigh is suddenly forced into 106 Chapter 7

Tackle at the moment of forceful hip flexion and adduction.

Figure 7.3. An athlete being tackled in the moment of a forceful hip fl exion during running and kicking can potentially put the groin muscles at risk of injury extension and the iliopsoas will try to decelerate the tendon that will sustain the lesion. In this situation movement by an instantaneous eccentric muscle the hip fl exors (iliopsoas, rectus femoris, and tensor action. facia latae) are also at risk of sustaining an injury. An acute strain of the lower abdominal muscles Lesions to the lower abdominal muscles and usually involves either the conjoint tendon (falx other structures associated to the inguinal canal inguinalis) where the tendons of the transverse can lead to a condition with some similarities abdominal muscle and the internal oblique muscle of a hernia (i.e., often called “sports hernia” or join and insert into the pubic tubercle or the rectus “incipient hernia”). A predisposition for her- abdominis muscle usually in the entheses at the nia development might be present, but the pri- pubic bone or in the distal myotendendinous junc- mary mechanism of injury is probably an acute tion. The typical mechanism is a traumatic episode trauma as described earlier, or a period of overuse where the athlete over-stretches the front of the as a result of a misbalance of the muscles acting groin and lower abdomen as in a forceful sliding on the pelvis and an intense strenuous activity tackle in soccer or an uncontrolled fall backward often involving exercises with many fast reactions where the hip is extended and the abdominal including sprinting, jumping, kicking, and sudden muscles are working hard to stop the fall by con- changes of direction. The nature of the lesion is tracting with great speed and force, often with an not always clear. It may be a strain or tear, infl am- eccentric contraction (Figure 7.4). The more rota- mation or degeneration at certain points of exces- tion involved in the fall either in the hip joint sive stress, an avulsion, hemorrhage or edema. It or in the torso, the more likely it is the conjoint is probably the result of the structural lesion to Preventing groin injuries 107

Recovery attempt with torso flexion and right rotation

CheckCheck oonn iicece lleadingeading ttoo torso/spinetorso/spine eextensionxtension andand llefteft rrotationotation

Check on ice leading to left hip extension, external rotational and abduction

Recovery attempt with left hip flexion, adduction and internal rotation

Figure 7.4. Secondary to a tackle or check on the ice, an athlete can put the groin muscles at risk resulting in overstretching the front of the groin and lower abdomen. Injury can occur with the initial insult or with the athlete’s attempts to recover

the muscles and/or tendons (i.e., rectus abdominis as mentioned earlier the adductors, iliopsoas, and muscle or insertion, the external oblique, internal abdominal muscles are primarily at risk of being oblique and/or transversalis muscle or aponeuro- injured. The adductor muscle group have been sis and the conjoint tendon) involving a weakness shown to be very important as stabilizers of the of the posterior inguinal wall without a clinically hip joint, and the interaction of the abdominal obvious hernia. muscles (in particular the transverse abdominis The pelvis is the centre of load transfer from muscle), the multifi di muscles deep in the low the upper extremities and the torso to the lower back and the pelvic fl oor muscles have been extremities and vice versa. As such it is depend- shown to be important for the stability of the low ent of both skeletal and articular stability as well spine and pelvis. The precise functions of the ili- as good neuromuscular stabilization. A number of opsoas are not fully understood, but the muscle muscle groups interact on the pelvis and hip and seems to work both as an important hip fl exor 108 Chapter 7

Hip flexor muscles

Abdominal muscles Hip adductor muscles

Sport like speedskating challenges Figure 7.5. Many ﬁ eld and ice sports challenge all the hip and torso muscle groups all the hip and torso muscle groups. In the sport especially when the athlete is taking of speed skating, these muscles are challenged a corner on the ice or is at the especially when an athlete is taking a corner or starting block taking off from the starting block

and as a pelvic stabilizer as well as a stabilizer for bony changes seen with the enthesopathy of the the lumbar spine. These lumbar and pelvis stabi- adductor longus insertion leads to an increased sig- lizing muscles are all constantly involved in most nal when examined with bone scan and with MRI sports-activities contributing with a considerable and to irregularities on X-ray. This is sometimes amount of both eccentric and concentric work called “osteitis pubis like changes” as it looks like and fast changes between these work forms. This the changes seen with infection of the joint. The makes them highly important but are also at risk changes are not diagnostic of groin injury since of sustaining an injury (Figure 7.5). they primarily are related to the amount of soccer The injury mechanism for developing groin or other sports undertaken. injuries with an insidious onset has not been Ice hockey player groin injuries may be caused proven, but it seems reasonable that fatigue, over- by the eccentric force of the adductors attempt- use or acute overload of any of the muscles pre- ing to decelerate the leg during a stride. However, viously discussed may lead to disturbance of the a large percentage of groin pain in these athletes interaction between these muscles leaving some may actually be due to inability to properly load of the structures with loads exceeding their ability. transfer from the legs and or torso to the pelvis. This may in turn lead to injuries with structural Studies examining healthy adults suggest that the damage to tissue and a need for repair. The ath- central nervous system deals with stabilization of lete will often try to compensate for this situation the spine and pelvis by contraction of the abdomi- and although they might succeed for a while, nal and multiﬁ dus muscles in anticipation of reac- gradually the pain and loss of function will take tive forces produced by lower limb movement. The over, and the athlete is not able to continue sport transversus abdominis and the oblique abdominal participation. The ability to react fast is impaired, muscles appear to contribute to a function not and sudden changes of direction, sprinting and related to the direction of lower limb movement strenuous sudden abdominal contractions as forces. A strength imbalance between the propul- when coughing and sneezing become painful. In sive muscles and the stabilizing muscles of the hip some athletes this impaired pelvic stability put and pelvis has been proposed as a mechanism for an increased stress on the symphysis joint lead- adductor strains in athletes (see Section “Key risk ing to a stress reaction that combined with the factors: how to identify athletes at risk”). The role Preventing groin injuries 109

Weak posterior lumbar segmental multifidus

Lead to

Overused and tight superficial erector spinae muscles

Causing further

Overuse of the adductor muscles as they try to stabilize and assist the abdominal muscles Figure 7.6. As possible cause of strength through length issues of the adductor muscle group leading to further potential for groin strain injury of the muscles of the torso (i.e., transverse abdomi- of the athlete population at risk, and the risk nus, obliques, diaphragm, multifi dus, pelvic fl oor) factors associated with injury for this popula- in stabilizing the pelvis such that the abductors tion (Table 7.4). Age and sports experience are and adductors can work explosively and not get factors that are in nature non-modifi able, but it strained remains unclear. Perhaps it is the balance is tempting to assume, that if increasing age is a risk to sustain groin injury, focus should be to of all the torso, pelvis, and hip muscles that is a look for methods to take off load and programs critical factor in groin injury. For example, weak that could strengthen the specifi c structures, that posterior lumbar segmental multifi dus muscles most frequently are injured in the “mature” ath- may lead to overused and resultant tight superfi - letes. If on the other hand decreased age and/or cial erector spinae muscles causing further poten- sports experience are risk factors, care must be tial overuse of the adductor muscles as they try to taken to implement preventive programs for this stabilize and assist the anterior torso muscles, that group, probably including both specifi c strength- is, abdominals (Figure 7.6). This situation might ening as well as exercises for pelvic stability and lead to strength through length issues of the educating the young athletes (and their coaches) adductor muscle group leading to further poten- in using common sense in the progression of tial for groin strain injury. sport specifi c training and in handling exercise related pain. Sport specifi city has been shown to be a risk Identifying risks in the training and factor in swimmers, who are at a risk of getting competition program adductor-related groin problems, if they are breaststroke specialists. A similar connection between Groin injury prevention strategies may be devel- groin injury and the specifi c activity of certain oped and evaluated if there is a good understanding positions or disciplines has not been shown in 110 Chapter 7 other sports, most likely because the number of nal muscle recruitment), unfortunately there are studies investigating this until now is very limited. very few studies that have examined the effect To prevent sport specifi city related groin injuries of possible preventive measures (Table 7.4). This development of modifi ed techniques that decrease section will summarize “best practices” for groin the load on the specifi c structures could probably injury prevention in sport, considering the lim- decrease the risk of groin injury. Another way ited but best evidence available identifying risk would be to strengthen the structures at risk. factors and prevention strategies for groin injury Too few sessions of pre-season sport specifi c to date. Globally, development of a sport-spe- training have been shown to be a risk factor in cifi c prevention strategy to reduce the risk of ice hockey. This is probably a refl ection of an groin injury in sport will include components of increased risk of sustaining an injury when par- adequate rehabilitation for previous injury, early ticipating in sports at a higher level and a higher identifi cation of sport-specifi c ROM and strength intensity that you are generally fi t for. An increase defi cits, and achieving sport-specifi c ROM and in pre-season sport-specifi c training and a subse- strength as well as muscle timing of recruitment quent decrease in groin injury may be supported requirements. by eccentric training of the thigh muscles as well as abdominal supporting muscular training. Pre- Adequate rehabilitation of previous season sport-specifi c training may allow for fur- injuries ther contraction and function-specifi c recruitment of these muscles, which might allow for their Previous groin injury is one of the best established more effective utilization and less onset of fatigue risk factors and it is generally considered a non- as the season progresses. Fatigue has been noted in modifi able factor. However, despite the fact that the literature to be a contributing factor for mus- a previous injury has occurred and this in itself is cle injury. As the research data available does not non-modifi able, there are other related factors that adequately differentiate training and competition are highly relevant and potentially modifi able. groin strain injury one can only insert a “clini- These factors may include how this injured ath- cal opinion” here. Clinically, there appears to be lete was treated, if there was specifi c treatment for three main time frames that groin strains appear the injury, if the treatment was functional for the to be more likely. These times are during the pre- demands of the athlete, and if the athlete returned season training when heavy training loads are to the sport including competition with complete being done, during the fi rst competitions of the rehabilitation of this injury (i.e., full pain free and year for explosive speed sports, that is, sprinters functional ROM regained, full strength on resisted and during the last half of the competition year for testing, concentric and eccentric muscle specifi c endurance type sports. Adequate pre-season and function retrained). It is important to use specifi c continued through season assessment and training treatment methods that treat both the dysfunc- of hip ROM as well as hip muscle strength/muscle tion related to the specifi c structural damage that balance and torso muscle recruitment timing may caused the groin pain (i.e., adductor tendon enthe- further minimize the risk of groin injuries. ses as well as to restore associated pelvic muscular instability by retraining the muscles of the torso as well as the muscles of the hip and pelvis). It is not Preventive measures enough to treat a damaged tendon insertion with steroid injections and time off from the sport and then return when the pain is gone. Likewise, only A number of more or less well-established risk treating with “core stability” exercises to stimulate factors have been mentioned earlier in this chap- the abdominal and low back muscles and then ter (previous groin injury, age, sport experience, return to sport is not a suffi cient treatment and sport specifi city, pre-season sport specifi c train- rehabilitation of a damaged tendon insertion to ing, hip ROM, hip muscle strength, and abdomi- prevent recurrence of the groin injury. Preventing groin injuries 111

To prevent recurrence of previous groin injuries, be found in a number of variations and many of treatment aiming at healing the structural damage these include abnormalities in the ROM of the should be combined with an exercise program to hip joints, in most cases reducing ROM. In the re-establish the pelvic stability and a rehabilita- last decade more attention has been given to tion program gradually including the demands the impingement problems of the hip joint. This and skills needed to participate in the particular problem includes groin pain and in most cases sport before allowing the athlete to return to full some degree of decreased ROM of the hip joint. participation. Otherwise there is a risk that the The two most prominent impingement diag- factors that originally led to the structural damage noses are known as Cam impingement and Pincer will again “take over” and combined with fatigue impingement. In both cases bony abnormali- because of lack of sport-specifi c rehabilitation may ties lead to potentially further structural damage eventually lead to groin re-injury and as often to the hip joint. They can both be found in ath- encountered a risk of other injuries as well. letes without groin or hip pain but with decreased ROM of the hip joints and potentially they are Increasing hip ROM probably a risk factor for developing groin pain. If the impingement problem is symptomatic with The ROM of the hip joint is suggested as a risk hip joint and groin pain, damage to the acetabular factor for groin injuries. There are many reasons cartilage as well as to the labrum of the hip joint is for pathologic changes of the hip joint ROM, often found. These osseous hip problems need in some of which are easily modifi able whereas oth- most cases to be treated surgically if symptomatic, ers are more diffi cult. Acquired tightness of the followed by a closely monitored rehabilitation rotators, fl exors, extensors, abductors or adduc- program to re-establish muscle strength and coor- tors of the hip joint are all potentially able to be dination related to the pelvis. In some more rare loosened with stretching exercises, soft tissue types of hip dysplasia surgery can be indicated to release techniques (manual therapy, massage, dry prevent the development of osteoarthosis in the needling, proprioceptive neuromuscular facilita- hip joint. It is not clear, whether any prevention tion techniques), as well as balanced muscle train- is indicated in cases of pain-free impingement, ing addressing both the affected muscles and the but theoretically there is a risk, that these patients antagonist muscles. One study found an increased develop groin injury and intra-articular damage hip abduction ROM after an exercise program of the hip joint. How these athletes should be including both concentric and eccentric adductor advised regarding further sports activities is not exercises but no stretching exercises for the adduc- clear and is currently a subject for discussion and tor muscles. Generally there is no evidence that ongoing scientifi c studies. stretching can prevent groin injuries. However there are indications that a normal ROM of the Strength training muscles and joints probably is important. In Box 7.1 some stretching exercises for the muscles The strength of the abductor and the adductor around the hip joint are described. muscles have been debated as possible risk fac- Capsular tightness of the hip joint can be found tors earlier in this chapter. One study suggests due to post-injury fi brosis reaction, as the result of that the ratio between adductors and abductors adaptation to decreased ROM for other reasons dur- are important and that pre-season strength training long periods of time or as an inherent general ing of the adductor muscles in ice hockey play- capsular tightness. The collagen tissue in the cap- ers with adductor/abductor strength ratio Ͻ80% sule is probably possible to stimulate to adaptation could decrease the number of adductor related to a larger ROM with exercises and manual therapy. groin injuries (Tyler et al., 2002). The study how- Decreased ROM of the hip joint related to bony ever had some methodological concerns and since abnormalities is another and much more diffi cult other studies have been confl icting regarding the problem to treat. Dysplasia of the hip joint can strength of the adductor and abductor muscles, 112 Chapter 7 the study does not provide conclusive evidence could help to identify established risk factors (pre- for this method of prevention. If, however, we also vious groin injury, age, sport experience, sport consider the protective effect of pre-season sport- specifi city, pre-season sport specifi c training, hip specifi c training in ice hockey, this also has impli- ROM, hip muscle strength, and abdominal muscle cations for supporting eccentric adductor strength recruitment). Development of a sport-specifi c pre- activity to reduce the risk of groin injury. vention strategy to reduce the risk of groin injury The combination of strengthening of the adduc- in sport should include components of adequate tors and the abductors with abdominal and low rehabilitation for previous injury, early identifi ca- back muscle recruitment is probably the area where tion of sport-specifi c ROM and strength defi cits, some of the most likely possibilities are available. A and achieving sport-specifi c ROM and strength as randomized treatment study including specifi c train- well as muscle timing of recruitment requirements ing of the adductor muscles (static, concentric, and especially in the torso and hip region. Additionally, eccentric), as well as exercises for the muscles related pre-season sport-specifi c training may allow for to the pelvis including the core stability principles, further contraction and function-specifi c recruit- showed a highly signifi cant effect in the treatment of ment of these muscles which might allow for their adductor-related groin injuries (Hölmich et al., 1999). more effective utilization and less onset of fatigue In another randomized controlled trial including as the season progresses. Adequate pre-season and 1022 male soccer players, the possible preventive continued through season assessment and training value of such an exercise program has been exam- of hip ROM as well as hip muscle strength/mus- ined. The exercises (Box 7.2) consisted of the follow- cle balance and torso muscle recruitment timing ing: (1) static isometric adduction exercises squeezing many further minimize groin injuries. a soccer ball between the feet and between the knees in the supine position, (2) dynamic adductor and abductor strengthening exercises (concentric and References eccentric) done with a partner, (3) coordination of the hip joint related muscles and the muscles of the torso using a dynamic exercise combining sit-up, Cusi, M.F., Juska-Butel, C.J., Garlick, D., Argyrous, G. (2001) Lumbopelvic stability and injury profi le in hip fl exion and adduction, (4) dynamic propriocep- rugby union players. New Zealand Journal of Sports tive exercise stimulating both concentric and eccen- Medicine 29, 14–18. tric strength utilizing the principles of core stability Emery, C., Meeuwisse, W. (2001) Risk factors for groin (i.e., including the muscles of the torso as well as the injuries in hockey. Medicine and Science in Sports and muscles of the lower extremities), and (5) stretching Exercise 33, 1423–1433. exercises for the iliopsoas muscle given the nature of Hölmich, P., Uhrskou, P., Ulnits, L., Kanstrup, I.L., secondary involvement of this muscle in the pres- Nielsen, M.B., Krogsgaard, K. (1999) Active physical training is an effective treatment of adductor related ence of groin pain. The trial found that the risk of groin pain in athletes—results of a randomised clinical sustaining a groin injury was decreased 31%, but the trial comparing two interventions. The Lancet 353, difference was not statistically signifi cant. Despite 439–443. the inconclusiveness of this study, the 31% reduc- Tyler, T., Nicholas, S., Campbell, R., Donellan, S., tion in the risk of getting a groin injury would be McHugh, M. (2002) The effectiveness of a preseason a considerable advantage, which probably would exercise program to prevent adductor muscle strains make it worth while for the soccer players to do the in professional ice hockey players. American Journal of Sports Medicine 30, 680–683. program.

Take-home message Further reading The best means to identify an athlete at risk for a groin injury may be for the athlete to undergo a Brukner, P., Khan, K., Bradshaw, C., Hölmich, P. (2006) preparticipation physiotherapy examination. This Acute hip and groin pain. In P. Brukner & K. Khan Preventing groin injuries 113

(eds.) Clinical Sports Medicine, pp. 394–404. McGraw- L. Engebretsen, H. Roos, T. Takala, & S.L-Y. Woo (eds.) Hill, Sydney. Textbook of Sports Medicine—Basic science and clinical Brukner, P., Khan, K., Bradshaw, C., Hölmich, P. (2006) aspects of sports injury and physical activity, pp. 616–637. Longstanding groin pain. In P. Brukner & K. Khan Blackwell Science Ltd, London. (eds.) Clinical Sports Medicine, pp. 405–426. McGraw- Maffey, L., Emery, C. (2007) What are the risk factors for Hill, Sydney. groin strain injury in sport? A systematic review of the Hölmich, P., Renström, P., Saartok, T. (2003) Hip, groin literature. Sports Medicine 37, 881–894. and pelvis. In M. Kjær, M. Krogsgaard, P. Magnusson, Chapter 8 Preventing low back pain Adad Baranto1, Tor Inge Andersen2 and Leif Swärd3

1Department of Orthopaedics, Sahlgrenska University, Göteborg, Sweden 2National Center of Spinal Disorders, National Center of Pain and Complex Disorders, Trondheim University Hospital, St Olav, Norway 3Department of Orthopaedics, Sahlgrenska University, Göteborg, Sweden

Epidemiology loads. It is therefore not surprising that a “red ﬂ ag” has been raised for the early selection of one sport and the early start of specialized training. Increased training levels

In the 1970s some studies showed positive effects Low back pain in young athletes of regular training among adolescents in physical Back pain symptoms in children and adoles- fi tness, technique, and coordination. This has led cents are different from those in adults and in to a common opinion that high doses of training many cases also have other causes than in adults for long periods of time at a young age are required (Sassmannshausen & Smith, 2002). The symptoms in order to become an elite athlete. Historically, in children are less distinct and they rarely have this has resulted in a trend to start training, com- neurological defi cits as in adults. Physicians diag- petition and specialization in one sport at a very nosing back pain in young athletes must have a young age. This means that many sports require specifi c understanding of these differences in order training with high intensity and with high load, to avoid incorrect diagnosis and harmful delays in often from a very young age. In many sports, it proper treatment. Therefore, diagnosis should be has been found that athletic training with the aim accurate and prompt in pediatric and adolescent of perfection requires monotonous and repetitive athletes, as most have a specifi c etiology. Back inju- strenuous exercises, leading to an increased risk ries account for 5–8% of all athletic injuries and of musculoskeletal morbidity and/or disturbed low back pain has experienced by 10–90% in young growth. A result of this is that overuse injuries elite athletes (Table 8.1) (Swärd et al., 1991; Baranto are an increasing problem in sports and have also et al., 2006). In one study it was found that 46% been more noticed among young athletes. of adolescent athletes reported low back pain com- It has also been shown that the growing spine pared to 18% of non-athletes (Kujala et al., 1996), is highly vulnerable to trauma, especially during and another study found a signifi cantly higher fre- the adolescent growth spurt (Baranto et al., 2006). quency of low back pain in young elite gymnasts In many sports, such as gymnastics, wrestling, (79%) than in controls (37%) (Swärd et al., 1991). and weight lifting, the growing spine is exposed In a study on divers the lifetime prevalence of to high loads and in some situations to extreme back pain was 89% (Baranto et al., 2006), which is signifi cantly higher than in previous reports (49%) on competitive divers. They also did study the Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing probability that back pain would appear within ISBN: 9781405162449 1 year (if there was no back pain history earlier)

114 Preventing low back pain 115

Table 8.1 Prevalence of radiological abnormalities on and found that almost on in two divers who did X-rays and MRI, and of symptoms of back pain among not have any history of back pain would suffer athletes (young and adults) in different sports. The from back pain within 1 year (Figure 8.1). results are estimates based on data from different studies. It has been reported that athletes with abnormalities in the thoracolumbar spine have more Radiological Thoracolumbar back pain than other athletes and non-athletes abnormalities (%) back pain (%) (Kujala et al., 1996; Sassmannshausen & Smith, Weightlifting 62–100 23–67 2002; Baranto et al., 2006). Low back pain among Wrestling 32–86 54–69 athletes may result from acute macro-trauma, Orienteering 71 50 repetitive micro-trauma, or stress (Jackson, 1979; Ice hockey 100 86 Diving 71 89 Swärd et al., 1991). Gymnastics 42 46–85 Soccer 36 36–58 Tennis 47 32–50 Low back pain in adult athletes Skiing – 63 The lumbar spine of athletes usually performs Rowing – 55 demanding and extreme tasks without problems.

Figure 8.1. (a) Baseline T2 weighted MRI examination in a 20-year-old female diver. (b) T2 weighted MRI at follow-up 5 years later shows moderate disc signal reduction of the L5–S1 disc (a) (b) (arrow) 116 Chapter 8

But the poorly conditioned athlete places himself 0 at great risk for back injury. 10 Studies have shown prevalence of low back pain 20 30 in athletes from 1% to 85% and that low back 40 pain is infl uenced by sport type, gender, training 50 intensity, frequency, and technique (Bartolozzi 60 et al., 1991; Kujala et al., 1996). The literature 70 shows confl icting results on which athletes are at 80 higher risk for low back pain or not, although low 90 Proportion pain (%) with back 100 back pain is clearly more frequent in some sports 0 10 20 than in others. The lifetime prevalence of low back Age (years) pain in wrestlers has been reported to 59%; signifi - cantly higher than that of an age-matched control Figure 8.2. The probability of back pain in elite divers. group (31%). A signifi cantly higher frequency of The probability that back pain will appear within 1 year (if low back pain has also been reported in elite gym- there was no back pain history earlier) is about 45%, that is, almost every other diver who has not had any back pain nasts (79%) than in controls (37%) (Swärd et al., history will suffer from back pain within 1 year 1991). In a prospective study of 134 former top athletes with mean age 33.2 years, it was found that wrestlers had the highest frequency of severe Radiological abnormalities in the low back pain (54%) as compared to tennis play- spine of athletes ers (32%), soccer players (36%), female and male gymnasts (29%), and non-athletes (32%) (Lundin Several studies of the thoracolumbar spine among et al., 2001). However, athletes as a group did not athletes in sports with great demands on the spine, have a higher frequency of back pain than non- have reported high frequencies of radiological athletes, despite signifi cantly more radiological abnormalities, on plain X-rays and magnetic reso- abnormalities among the athletes. In fact, low nance tomography (MRI) (Figure 8.2), compared back pain was less common in former elite athletes to other athletes and non-athletes (Table 8.1) (29%) than in non-athletes (44%). Low back pain (Alexander, 1977; Goldstein et al., 1991; Swärd has also been reported to be more frequent among et al., 1991; Kujala et al., 1996; Lundin et al., 2001; cross-country skiers (63%) and rowers (55%) than Baranto et al., 2006). Typical fi ndings are disc orienteerers (49%) and a control group of non-ath- degeneration and abnormalities affecting the ver- letes (47%) (Bahr et al., 2004). tebral endplates and the vertebral ring apophyses. Disc degeneration and spondylolysis are the Injury rather than the duration of athletic loading most common structural abnormalities associ- seems important in the etiology of an early degen- ated with low back pain in athletes (Bono, 2004). erative process in the thoracolumbar spine among Muscle strains and interspinous ligament sprains athletes (Swärd et al., 1991; Kujala et al., 1996). have been reported in only one study to be the Abnormalities in the spine among top-level ath- most common injuries causing low back pain in letes are relatively uncommon before the adolescent athletes at any age. However, there are no other growth spurt but thereafter found in increasing fre- studies showing evidence for muscle strains being quency (Goldstein et al., 1991; Kujala et al., 1996; the most common cause for low back pain in Baranto et al., 2006). This is an indication that athletes. the growing spine is highly vulnerable to trauma. One of the most common reasons for missed There is limited knowledge on the effects of high playing time by professional athletes is pain and physical loading and development of injuries in dysfunction of the lumbar spine. Other studies the spine during growth and as to whether these have also reported that back pain in many cases injuries contribute to low back pain, progression of was signifi cant enough to interfere with training disc degeneration or other injuries into adulthood. and competition (Jackson, 1979). Despite the long-known fact that intervertebral Preventing low back pain 117 disc degeneration is more frequent among adolescent athletes than in non-athletes, little has been done to advise the individual athletes or the sports- governing societies to prevent such injuries. An MRI study of the lumbar spine of professional fast bowlers in cricket showed that they have a relatively higher prevalence of multi-level disc degeneration, a unique pattern of non-dominant side muscular hypertrophy and non-dominate side stress lesions of the lumbar posterior elements. It was found that disc degeneration was not a precursor to lumbar stress changes, but individuals with bilateral stress fractures had severe disc degeneration in all fast bowlers who had a chronic bilateral L5 stress fracture. It was also showed that acute bony stress can be reliably identifi ed using an MRI. An MRI can also detect other structures associated with low lumbar injury, such as intervertebral discs, facet joints, lumbar muscles, and ligaments to be injured (Ranson et al., 2005).

Spondylolysis

Spondylolysis is a radiological diagnosis and means a defect within the bone of the posterior part of neural arch, that is, pars interarticularis. The frequency of spondylolysis in the general population is found to be 4–6% (Figure 8.3). However, the incidence in athletes is much higher, especially in athletes with low back pain where, in one of these studies, spondylolysis was found Figure 8.3. Schematic and CT scan showing spondylolysis. in 47% of the cases (Sassmannshausen & Smith, Spondylolisthesis is also showed on the drawing to the left 2002). Risk factors are positive family history and as the anterior movement of the upper vertebra in relation co-existing spinal anomalies. Repetitive hyperex- to the lower tension has been shown to be a major risk factor, particularly in gymnastics, ﬁ gure skating, dancing, and among football linesmen. Spondylolysis Anatomy and function of the spine was found in a higher frequency than expected among young (range 17–25 years) elite athletes Development of the spine representing female gymnastics (19.2%), male gymnastics (11.5%), tennis (10.0%), wrestling The vertebral column consists of a series of linked (6.7%), soccer (6.5%), and non-athletes (3.3%). segments, which serve as the main supporting Other authors have reported a high prevalence structure of the body. It also allows sufﬁ cient phys- of spondylolysis in other sports, that is, gym- iological motion between the body parts and also nasts, American football players, divers, wres- protects the spinal cord from damaging forces. tlers, weight lifters, rowers, tennis players, soccer The spine is composed of vertebrae, intervertebral players. discs, facet joints, ligaments, and muscles. 118 Chapter 8

Development of the spine starts in early life. to create failure of the degenerated discs as com- The vertebra consists of the vertebral body and the pared to non-degenerated discs. neural arch containing transverse, articular, and spinous processes. The growth of vertebral bodies Muscles of the lumbar spine proceeds from the osseous surface of the cartilagi- For descriptive purposes, the spine muscles may be nous epiphyseal plates that cover the end plates. divided into three groups: superfi cial, intermedi- These growth plates are, unlike the growth plates ate, and deep. The superfi cial (trapezius, latissimus of the long bones, not covered by a bony epiphy- dorsi, levator scapulae, and rhomboid muscles) seal plate. At the periphery of the epiphyseal end- and intermediate (serratus posterior superior and plates, in the growing vertebrae, there are recesses inferior muscles) groups are extrinsic back muscles where the vertebral ring apophyses are formed. that are concerned with movements of the limbs. They are the insertion site for the annulus fi brosus The deep group (semispinalis, multifi dus, rotators, of the discs. The area between the ring apophyses interspinales, and intertransversarii muscles) consti- and the vertebral body are the weakest part of the tute the intrinsic back muscles that are concerned spine during growth. The ring apophysis starts to with control of the vertebral column. The muscles ossify at about 13 years of age and begins to fuse quadratus lumborum, iliopsoas and the abdominal with the vertebral body at about 17 years of age. At muscles are also important lumbar spine muscles. completed growth, each vertebra has an elevated rim and a central depression of the endplates. Core stability/neuromuscular control The etiology and development of intervertebral disc degeneration and abnormalities affecting the The term stability is a mechanical concept that most vertebral endplates and ring apophyses are not be relate to, but which can be diffi cult to explain fully known. The etiology of disc degeneration when applied to the body in motion. The term is is believed to be multifactorial. As evidenced by borrowed from traditional mechanics and describes the high frequency of abnormalities in the spine the ability of a body to remain in the same position of adolescent athletes, mechanical trauma at a while forces are being exerted on it. However, when young age appears to be a factor of importance performing in sports, body confi guration is rarely especially in sports with great demands on the static; in fact, it constantly and rapidly changes. back (Jackson, 1979; Swärd et al., 1990; Goldstein Thus, the athlete must be suffi ciently stable and et al., 1991; Lundin et al., 2001; Baranto et al., at the same time mobile in order to adapt to the 2006). demands placed on them during various movement Little is known about the biomechanics and patterns. The stability and mobility of a joint is pri- strength of the degenerated disk. In an experi- marily dependent on three factors: passive structures mental study, a degenerative disc was created by (bones, ligaments, joint capsules), active structures drilling a hole through the cranial endplate of a (muscles), and the ability to successfully coordinate lumbar vertebra into the disc. The results in this information and activate the muscles (the central study were that twice the axial load was required and peripheral nervous system) (Figure 8.4). Thus,

Control system (nervous system)

Passive subsystem Active subsystem (ligaments, bone, (muscles) joint capsule) Figure 8.4. Panjabi’s model of stability Preventing low back pain 119 effi cient coordination of the joint systems is required can cause low back pain during training cycles and for the athlete to be able to adapt to the demands of sports competition. Ideal posture, analyzed from sports. This ability is also often referred to as neu- the side, has been described as the perfect distri- romuscular (motor) control. In training terminology bution of weight around the center of gravity in this is often referred to as stability, and when refer- which the agonist and antagonist muscles should ring to the low back pelvis and hip region, “core be in perfect balance regarding fl exibility and stability.” strength. Perfect muscular balance in relation to Based on recent research, it has become common posture will provide for optimum effi ciency dur- to categorize the muscles according to their func- ing movement of sports and daily activities. This tion and location in the body. More simply put, the perfect balance is however diffi cult to achieve. deep paraspinal muscles, with high endurance and fi ne motor skills, stabilize the joint systems (here Hyperlordosis or excessive curvature the lower back, pelvis, and hip), whereas the super- of the lower spine fi cial muscles, with less endurance, produce pro- pulsion. The larger the forces produced, the greater Another cause of low back pain in adolescent ath- the importance of the ability to stabilize, both for letes is hyperlordosis or a lordotic lumbar back, the effective utilization of muscle activity (effective which is most commonly due to a forward tilting technique), and for preventing injuries. Thus, the of the pelvis (Sassmannshausen & Smith, 2002). paraspinal muscles can have a direct infl uence on Forward tilting of the pelvis causes high loads on segmental stability and control of the lumbar spine the intervertebral discs and the facet joints, result- due to their attachments to the spinal column. ing in high stress in the pars interarticularis of the Coordinated contraction of the lumbar paraspinal neural arc of the lower lumbar spine. muscles with the abdominal wall muscles is thought It was found in a study on young athletes that to have a stabilizing effect on the lumbar spinal seg- the sacro-horizontal angle was larger in athletes ments, and therefore providing a safe platform for with spondylolysis as compared to those without. trunk movement. Dysfunction of these muscles has They, therefore, suggested that an increased sacro- been suggested to be a signifi cant risk factor in the horizontal angle may predispose the individual to etiology and chronicity of low back pain. spondylolysis and spondylolisthesis, especially in combination with the high mechanical loads sustained in certain sports. Key risk factors: how to identify The posture of a forward tilting pelvis causes an athletes at risk increase in the effective curve of the spine. The pathomechanism behind hyperlordosis in children is that the thoracolumbar fascia becomes Improper technique tight during the adolescent growth spurt due to Improper sport technique and weak abdominal more rapid growth of the axial skeleton than the and leg muscles have been shown to increase the fascia. The thoracolumbar fascia consists of three risk for spinal injuries. In a study of volleyball layers of fascia that envelop the muscles of the players as an example, Bartolozzi et al. (1991) lumbar spine, effectively separating them into found that only 21% of athletes using proper three compartments. Pathologic tightness occurs technique and did not overtrain had degenerative when the skeletal growth exceeds the capacity of fi ndings in the spine, compared to 62% of athletes the soft tissues to remain limber. This tightness using improper technique and overtraining. may cause traction apophysitis at the iliac crest and spinous processes or impingement of adja- Posture cent spinous processes. The risk factors are rapid growth and sports that require strong hamstrings, Lower back pain has a strong relationship to pos- which could exacerbate tightness. The symptoms ture and it is well known that poor posture is often caused by hyperlordosis are activity-related low a result of muscular imbalance. This imbalance back pain. 120 Chapter 8

Age Sex

During growth the nucleus pulposus has a high As girls are more fl exible and have more joint lax- water content, thereby giving the disc a higher ity, they may also have greater risk spine injuries, mobility, which accepts movements that put high such as disc degeneration, spondylolysis, and stresses on the facet joints and posterior elements facet joint syndrome. The same study on rowers of the vertebra including pars interarticularis. As and cross-country skiers showed that sex was an the degeneration of the disc starts early in life the independent risk factor for low back pain. Women elasticity decreases, after the growth spurt the disc were 35% more likely to report low back pain epi- will therefore quickly become stiffer. sodes during the previous 12 months than men. The degenerative changes found in adoles- cence in divers may be related to acute spine inju- Previous injury ries occurring during the pubertal growth spurt early in the athletic career (Baranto et al., 2006). It has been found that spondylolysis increases the The results from the several studies suggest that risk for disc degeneration. It has also been shown degenerative changes are common among young that back pain results in decreased muscle volume elite athletes and that trauma to the thoracolum- and strength. Therefore a thorough rehabilitation bar spine during the growth spurt is particularly is mandatory after every episode of back pain or harmful (Goldstein et al., 1991; Kujala et al., 1996; back injury. Baranto et al., 2006). The degenerative changes are probably caused by repeated acute injuries, which earlier in the literature has been reported to be of Typical injury mechanisms: examples etiological importance for the early degenerative from high-risk sports process in lumbar spine among athletes, rather than several years of heavy loading on the spine Acute trauma or repetitive stress (Hellström et al., 1990; Goldstein et al., 1991; Swärd et al., 1991; Kujala et al., 1996; Lundin et Acute macro-trauma, repetitive micro-trauma/ al., 2001). In divers, the abnormalities were found stress, or a combination of these two mechanisms from the age of 12 years and deterioration was can result in spine injuries in adolescent athletes, found in only one of the divers under 16 years, resulting in low back pain (Jackson, 1979; Swärd but in 73% of those over 16 years (Baranto et al., et al., 1991). Repetitive bending (e.g., in gymnas- 2006). This supports the statement that degenera- tics and diving) and twisting (e.g., in tennis and tive abnormalities occur at early age, probably due baseball) of the back increases the risk for spinal to acute injuries, and deterioration of the abnor- injuries in athletes. malities is due to the duration of heavy loading on In an acute trauma situation, the injury patterns the spine. are different in growing individuals when com- Although there are clearly sports which put the pared to the injury patterns of adults. This was child and adolescent spine at high risk of inju- highlighted in a study on cervical spine injuries ries, such as gymnastics and competitive diving, it in traffi c accident victims. They found in spines would be expected that the risk of low back prob- of adolescent victims that they had an avulsion lems increases with age as degenerative changes injury of the vertebral endplate (the growth plate), become more prevalent. When examining groups whereas the adult spines had a vertebral body frac- of adult competitive athletes in sports character- ture or a rupture of the disc. This indicates that ized by repetitive low back fl exion (cross-country the weakest part of the growing spine is the verte- skiing) or extension (rowing) loads, age is an inde- bral growth zone. pendent risk factor for injury. In fact, the risk of Regarding repetitive stress we have performed reporting low back pain within a 12-month period an experimental study on functional spinal units increases by 19% for every 5-year increase in age. from young porcine spines where they were Preventing low back pain 121 vibrated with 20,000 cycles and then axially com- person performed half-squat exercises with weights pressed to failure. The cycling load was chosen to ϳ1.6 times the body weight, the compression forces be equivalent to a soccer game or a long distance across the L3–L4 disc were about 10 times the body race. In this study there were no statistically sig- weight. In these studies, the authors found that nifi cant differences between specimens exposed increasing lumbar fl exion was the most infl uential to vibrations and non-vibrated specimens with factor affecting compressive loads (Bono, 2004). respect to ultimate axial compression strength. In several studies we have analyzed the strength The endplate and the growth zone were the weak- of the vertebral functional complex and also est parts in both cases. described the injury pattern at overload. In radiographic and MRI studies it has been found Loading patterns associated with abnormalities that can be explained by these injury experiments, for example, the over representation of vertebral growth disturbances found in athletes A combination of different kinds of load is respon- in the thoracolumbar junction. The most probable sible for injuries in the spine of athletes. A single explanation for this is that the loads are highest in load may cause a specifi c injury, but in the major- the anterior part of the vertebral bodies resulting ity of injuries there are combinations of loads. in an injury to the area of the ring apophyses and Heavy loads on the growing spine are the key risk that the energy in a rotation overload, due to the factor for causing injuries in young athletes. The brute change in facet joint orientation in the lower following describes the different loading patterns thoracic spine from allowing to restricting rotation, on the athletic spine. is transformed from the stable facet joints to the mobile weaker anterior part of the vertebrae. This causes an injury affecting the ring apophysis and Compression loads thereby a disturbance growth, resulting in wedged Compression loads may cause injury of the vertebrae and a Scheuermann kyfosis, which is also intervertebral disc (degeneration, low signal inten- called traumatic form of Scheuermann’s disease. sity on MRI), the ring apophysis, and the endplate Alexander (1977) suggested in the 1970s that (growth abnormalities such as Schmorl’s nodes abnormalities such as endplate changes, Schmorl’s and Scheuermann’s disease). nodes, apophyseal ring fractures and abnormal During various athletic activities, high loads are confi guration of the vertebral body are trau- produced on the spine and every different sport matic forms of Scheuermann’s disease and a com- places unique demands on the spine (Bono, 2004). mon fi nding in athletes. The traumatic form of For example, in a professional golf player, a swing Scheuermann’s disease involves in many cases produces 7500 N of compressive force across the only one vertebra and has its peak incidence at the L3–L4 disc. In another study, the average com- thoracolumbar junction (Alexander, 1977). These pression loads measured were Ͼ17,000 N in the fi ndings are frequent in sports with repetitive fl ex- L4–L5 disc in competitive weightlifters (Table 8.2). ion, extension, and rotation of the spine, such as Cappozzo et al. found in a similar study that when a gymnastics and wrestling. The symptoms are low back pain in high frequency accentuated in fl ex- Table 8.2 Spinal loads have been measured or estimated ion (Sassmannshausen & Smith, 2002). in different sports. Flexion and extension compression Sport Maximum compressive force (N) Flexion and extension compression loads also Golfers 6,000 cause injury of the intervertebral disc, the ring Rowers 6,000 apophysis, the endplate (growth abnormalities American football (linemen) 15,000 such as Schmorl’s nodes and Scheuermann’s dis- Weightlifters 15,000 ease) and of the facet joints. There is experimental 122 Chapter 8

Figure 8.5. The role of the facet joints during fl exion (a) Neutral position, (b) sagittal rotation causes the inferior articular process of the facet joint to lift upward, leaving a gap between it and the superior articular process. Anterior sagittal translation is allowed due to this gap. Finally, upon translation, the B B inferior articular process again impacts the superior articular process, limiting additional (a) (b) fl exion evidence that the spine is more sensitive for inju- studies showed that, when compressed in fl ex- ries during bending movements and especially ion or extension, the weakest part was the growth during extension compression. zone, and, to a lesser extent, the endplate, and the The extension movements in the intervertebral injury was more extensive in extension loading joints behave conversely to movements in fl exion. than during fl exion loading. The vertebral bodies rotate posteriorly and also The facet joints play a great role in maintain- undergo a small posterior translation in the sagittal ing the stability of the lumbar spine in fl exion. To plane. In addition to the tension in the disc, exten- understand these mechanisms it is important to sion movement is resisted by bony impact between recognize that fl exion involves both anterior sagit- the spinous and articular processes, the laminae tal rotation and anterior sagittal translation (Figure and also by the capsule of the facet joint. The poste- 8.5). During fl exion, the highest pressure is recorded rior ligaments are not critical for limiting extension. at the antero-medial part of the lumbar facet joint. However, the well-developed anterior longitudinal Each facet joint capsule, acting as a ligament, can ligament and the anterior portion of the annulus resist about 600 N and the tension developed in it fi brosus and the facet joints are important inhibi- during fl exion is enough to bend the inferior artic- tors of hyperextension and posterior translation. ular processes downward and forward about 5º. In an experimental study performed on func- During fl exion, the weight of the trunk exerts com- tional spinal units from adolescent male pigs, which pressive and shear forces on the intervertebral disc, were exposed to fl exion–compression or extension– which are proportional to the angle of inclination compression loading to failure, fractures/separations of the inter-body joint. were seen in the growth zone anteriorly and more frequently, posteriorly in spines exposed to fl exion– Rotation compression compression. In extension–compression such injuries occurred only anteriorly. In another experi- Rotation compression loads also cause injury of mental study we found that the experimentally the intervertebral disc, the ring apophysis, the degenerative discs in the fl exion–compression endplate and of the facet joints. group required four times more compression load Rotation of the lumbar spine involves torsion of before failure than normal adolescent spine units, the intervertebral discs and the impact of the facet while the degenerated extension–compression group joints. All the fi bers of the annulus fi brosus that are required only 60% more load than normal. These inclined toward the direction of rotation during results support the clinical impression that com- axial rotation will be strained and the others will be pression in extension or fl exion is more likely to relaxed. It has been calculated that the maximum cause spinal injuries than axial compression alone, range of rotation of an intervertebral disc is about 3º and that the spine is more vulnerable in extension– and rotation beyond this range will result in micro- compression than in fl exion–compression. These injuries in the collagen fi bers. The facet joints and, Preventing low back pain 123

18 The injury mechanism is related to the takeoff, Male athletes (n = 117) 16 Non-athletes (n = 30) fl ight and the entry phases, and each phase can 14 cause different spine injuries (Badman & Rechtine, 12 2004). The average entry speed into the water is 10 8 between 8.4 m/s (1 m springboard) and 14.0 m/s 6 (10 m springboard). At impact a speed reduction of 4 more than 50% within a fraction of a second has 2 been demonstrated, resulting in tremendous axial 0 Number of vertebrae load on the spine creating signifi cant potential for 2 injuries. This means that tremendous axial forces 4 are generated upon impact, creating signifi cant 6 Th5 6 7 8 9 10 11 12 L1 2 3 4 5 potential for spinal injury. Inadequate body roll Level can ultimately result in lateral fl exion and rotation through the lumbar spine, during this phase. Figure 8.6. Athletes have degenerative abnormalities Several clinical studies have shown that injuries on X-ray and MRI in the thoracic spine and also in the junction between the thoracic and lumbar spine in to the growing spine are common and it can be contrast to non-athletes. assumed that these injuries commonly occur during the adolescent growth spurt. Experimental to a certain degree, the posterior ligaments protect studies indicate that certain loads in extension and the intervertebral disc from excessive rotation. fl exion compression with or without disc degener- Rotation injuries cause injuries mainly in the ation result in predictable injury patterns involv- thoracolumbar junction due to the facet joint con- ing the disc and adjacent growth zones. These fi guration. The facet joints from Th12 to S1 are results may serve as a basis for further clinical formed to restrict rotation. Therefore repetitive studies of injury mechanisms in sports with heavy rotation in fl exion or extension in sports, such as loads on the spine. However, this will require tennis, creates overuse injuries in this part of the sophisticated standardized analysis of movements spine, traumatic form of Scheuermann’s disease or and loads on the spine during the execution of Mb. Swärd (Swärd et al., 1991; Baranto et al., 2006). the sports activities in training and competition, Swärd was one of the fi rst who found these degen- perhaps similar to the automated kinematic and erative abnormalities in athletes (Figure 8.6). The kinetic computer-analyzed gait analyses systems traumatic form of Scheuermann’s disease involves that have gained acceptance. Such motion analy- only one vertebra and has its peak incidence at L1 ses must be matched with the injury patterns of (Alexander, 1977). These fi ndings are frequent in the particular sport, in order to defi ne the critical sports with repetitive fl exion and extension, such movements with regard to risk for injury of the as gymnastics, tennis, and wrestling (Lundin et al., spine. Also the infl uence of age, gender, training 2001). The symptoms are low back pain accentu- intensity and individual technique on the devel- ated in fl exion (Sassmannshausen & Smith, 2002). opment of back pain, and spinal injuries needs to be studied further. Injury mechanism in diving and acrobatic sports Injury mechanisms for spine injuries in other sports Competitive diving puts high demands on the spinal column. The exposure of axial load on the spine There are different maneuvers and some times a of competitive divers is well described. Flexion and combination of maneuvers causing spinal inju- extension bending occur in most diving maneuvers ries in different sports. In tennis, rotation, fl exion and axial loading, shearing and torsional stresses and extension loads cause spinal injuries. In gym- act through multiple spinal segments, creating a nastics, it is the extreme fl exion- and extension– potential for injuries (Badman & Rechtine, 2004). compression loading and axial–compression loading 124 Chapter 8 that are responsible for injuries. In weightlifting which puts the annulus fi brosus at risk for injury. axial–compression loads cause spinal injuries. Top swimmers are at an increased risk for injuries Heavy loads in the spine are obvious in other because of exaggerated movements that increase fl ex- sports, such as wrestling and gymnastics, where ion and extension. The lumbar facet pain increases forceful bending movements are exerted at high with strokes that accentuate lumbar spine extension, speed. Other sports involve mainly one-sided such as breaststroke and butterfl y. Finally, in supine stress and loads, such as in tennis, American foot- swimming extension of the cervical spine induces ball, rowing, and soccer. lumbar extension, resulting in increased stress on This is supported by the fi ndings in the spine the pars interarticularis and the facet joints. of athletes in sports involving “fl ight.” During these activities, the athlete is airborne and lands on a hard surface, such as the fl oor in gymnastics, Identifying risks in the training and or the water, such as in diving maneuvers. Other competition program activities associated with spinal injuries include blocking in football, takedowns in wrestling, The amount of training and competition is of swinging a bat in baseball, tackling in ice hockey great importance for overuse injuries of the spine and use of heavy weights and attempts at complex in athletes.Goldstein et al. (1991) reported a strong free-weight lifts in weight training. correlation between development of degenerative In baseball, the players are prone to trunk rota- changes and back pain in gymnasts, and the fre- tion injuries as well as the less common trunk fl ex- quency of back pain was suggested to correlate to ion injuries. Loads generated through swinging a the level of activity. In contradiction to these fi nd- bat and accelerating a baseball produces disc and ings, Lundin et al. (2001) found, in a study of elite posterior element injuries. Injuries seen in infi eld- athletes representing wrestling, gymnastics, soccer, ers in baseball are mainly of the fl exion bending and tennis, that the athletes did not report more and lifting type. back pain than non-athletes (all athletes 60%, non- In American football, tackling, blocking, running, athletes 61%, female gymnasts 67%), despite signif- and throwing the ball all involve contact between icantly more radiological changes. The difference opponents that can cause a multitude of spine inju- between these two studies may be due to the fact ries. For example, when a player is reaching for a that in the study by Goldstein et al. (1991) the ath- pass as his opponent drives a shoulder into the fl ank letes were younger (mean age in female gymnasts he may be subjected to a quick forced hyperexten- 16.6 years) and still active in their sport, while in sion, when the spine is most vulnerable to trauma. the study by Lundin et al. (2001) the individu- The facet joints are at risk with hyperextension of als were older (mean age in female gymnasts 30.6 the lumbar spine. As well as protecting the spine years, all athletes 33.1 years) and they were mostly against fl exion injuries the increased paraspinal mus- former, rather than active, elite athletes. culature causes an unbalanced hyperextension force, Goldstein et al. (1991) found that 57% of the which puts the pars interarticularis at great risk. gymnasts who trained 15 h or more per week had The etiology of lumbar stress injury in fast bowl- degenerative changes on MRI, as compared to 13% ers in cricket has been shown to be multifacto- in those who trained less, and they concluded that rial. Asymmetrical development of the paraspinal the amount of training is of importance for the musculature, particularly quadratus lumborum, development of spinal injuries. was associated to lumbar stress injuries in elite fast cricket bowlers. The lumbar spine was found to be the most com- Prevention methods monly injured site in swimmers, divers, and water polo players and synchronized swimmers. Freestyle and backstroke increase lumbar segmental axial Low back injuries in adolescent athletes are a seri- rotation and therefore increase torque forces most, ous problem. However, if diagnosed and treated Preventing low back pain 125 properly, the athlete usually can return also to vig- athletes. To prevent spinal injuries the most orous activities. Many of the sport injuries are the important factor is to avoid high loads on the result of inadequate training, pore technique, but spine of athletes before the spine is fully grown, also structural anatomical weaknesses in the body. which means at least until after the age of 18 Unfortunately, there is a lack of scientifi cally docu- years. It is also important to avoid extreme bend- mented prevention methods for preventing spinal ing movements of the spine in sports when it is injuries in athletes. The following are best-practice possible, even if this is probably not realistic in recommendations based on our current under- many sports. The amount of training is of funda- standing of risk factors and injury mechanisms mental importance to reduce and avoid overuse discussed earlier. injuries on the spine in athletes. Competition Only when critical motion patterns and loads schedules should also be adjusted to the biologic in specifi c sports can be identifi ed, prevention age of the athletes. Young athletes should concen- may be possible. In order to avoid harmful motion trate on coordination, techniques, and balance patterns, rules and regulations, as well as scoring before the growth spurt. systems in esthetic sports, may have to be modi- Adults can help adolescent athletes prevent fi ed. Since sport rules and regulations usually have spinal injury. For example, coaches can institute historical origin and governing bodies tend to be shorter practices. Properly trained coaches, ath- very protective regarding new or modifi ed age- letic trainers, parents, or other adults can super- related rules in sports, considerable efforts and vise training sessions and mostly be aware of the convincing evidence will be needed in order to weakness of the growing spine and the relation to implement modifi cations of rules and regulations the growth spurt. They also can teach proper tech- when needed. Presently, little scientifi c evidence nique for weight training and various exercises. of this kind is available. Until such information The athlete with back pain must have a rehabili- is available, prevention must be based on indirect tation concentrating on technique, fl exibility, and evidence, such as the overrepresentation of certain muscle control to withstand the high demands of injuries in a sport. Thus, more general restrictions their sport. can be applied, for example, appropriate (biological) age limits for advanced muscular strength training Prevention principles with weights, limitations of repetitions of strenuous activities at a young age, and avoidance of inappro- On the basis of our current understanding of risk priate exercises that carry increased risk of injury. factors and injury mechanisms, the following All this requires improved education of trainers, four principles are recommended to prevent back coaches, and sport-governing bodies, as well as problems: education of the young athletes themselves, little 1. Avoid exercise straining the back with weights of which exists today. Medical personnel, includ- until the spinal column has stopped growing. ing physicians and physical therapists, need to 2. Avoid heavy strain in extreme positions take a more active role in preventing sports inju- whenever possible. ries, by educational and other activities at all lev- 3. Develop suffi cient strength, stability, and els, including young athletes. coordination in the back/pelvis and hip to meet As described in the earlier section the spine the demands of the various characteristics of the is in great risk for injuries due to extreme loads different sports. on the spine in axial compression, hyperfl ex- 4. Emphasize training that improves techniques, ion and hyperextension bending, rotation, and balance, and coordination. fi nally a combination of the loads. It is also well Unfavorable techniques may be due to insuffi cient documented that the spine is most vulnerable to strength, stability, coordination, etc. One exam- trauma during the growth spurt. Furthermore, the ple of this may be a handball player who is weak amount of training and competition is of great in the lower part of the abdominal muscles, result- importance for overuse injuries of the spine in ing in hyperextension of the lower back when 126 Chapter 8 executing a pass/shot on goal. The player will mobility and strength in the muscles of the back, be particularly at risk if the hip fl exors are short, abdomen, and hip joint. Control of the pelvic causing reduced mobility in the extension of the region is critically important, since it represents thoracic spinal column. A large part of the strain the center of the transfer of force between the is thus put on the lower back. In order to pre- upper body and the legs. vent problems in athletes like this, it is important to strengthen the lower abdominal muscles and Stability training/neuromuscular control increase mobility in the hip and thoracic spine. (Box 8.2) Another example is cross-country skiing, where many athletes also have lower back problems Neuromuscular control training (often referred (Bahr et al., 2004). One reason for this may be to as “core stability” training) aims to make the unfavorable technique in the double-pole push, athlete able to maintain a favorable position for where the athlete moves too far forward, causing the lower back, pelvic area, and hip area dur- extreme fl exion in the lower back. This places a ing various loading conditions. By maintaining a strain on the back, especially if the athlete does favorable position, the impact on the tissues and not have suffi cient strength and stability in the structures of the lower back is reduced. back/pelvis and hips. A shorter forward motion, The exercises are also well suited for reveal- where the back is kept in more of a mid-position is ing reduced neuromuscular control and reduced likely to both prevent injuries and be a more effi - strength in the muscles (“weak links”). The term cient technique. “weak link” denotes a weak point in a muscle syn- The selection of exercises to prevent low back ergy. The objective of core stability exercises is to problems should refl ect the demands of the sport, optimize control and force transfer in the lower designed to enable the athlete to meet the bio- back, pelvis, and hips with the least amount of force mechanical demands placed on the lower back. lost and the least amount of strain on the back. Although different sports have different demands, There are several different ways of training sta- the principles of preventive training are simi- bility/neuromuscular control. Studies have shown lar and the exercises can be grouped into three that two effective ways of improving/restoring categories. neuromuscular control is to: 1. Awareness exercises 1. Train in a closed kinetic chain. 2. Stability training/neuromuscular control 2. Train on an unstable surface. 3. Dynamic strength training of the muscles in Training in a closed kinetic chain means that the the abdomen and back. part of the body being trained is the one bearing weight. One example is the squat exercise. One example of the contrary, a training exercise in an Awareness exercises (Box 8.1) open kinetic chain, is working the quadriceps in Awareness exercises are intended to improve con- a knee extension machine. The squat is the more trol of the pelvic area in order to fi nd a favorable functional of these exercises. Any training in an position for the lower back. The objective is to open kinetic chain, such as knee extension, is make the athlete aware of the position and angle effective for isolating a certain muscle group, but of the pelvis, to avoid putting the spinal column less effective to develop neuromuscular control. in a position where it is at increased risk for inju- Changes in joint position and muscle tension are ries. The term pelvic position denotes the position recorded and transmitted to the central nervous of the pelvis in relation to the other body sections. system. This information is vital for the muscles to The position of the pelvis may be changed with- be able to successfully activate and maintain con- out changing the curvature of the back. If the pel- trol of joint position. vis is tilted forward, lumbar lordosis will increase. Exercising on an unstable surface further chal- The pelvic angle and the curvature of the spine lenges the neuromuscular control. Studies indicate are thus interrelated. This may be infl uenced by that exercises done on unstable surfaces activate Preventing low back pain 127

Box 8.1 Introduction to awareness exercises, examples of exercises

Pelvis tilt lying on back Flexing lower back sideways Starting position: Lying on back with bent hip and knees. Starting position: Lying on the back with legs straight. Execution: Tighten abdominal muscles so that the lower back Execution: First pull the iliac crest on one side upward, and touches the fl oor. Then tighten the muscles in the back to then the other side. curve the lower back and lift it off the fl oor. Note: Athlete fl exes lower back sideways Note: Athlete produces a fl exing motion in the pelvis.

Pelvis fl ex in standing position Starting position: Standing up. Execution: Tighten abdominal muscles to that the lower back curves outward. Then tighten the muscles in the back to curve the lower back inward. Flexing lower back sideways Note: Athlete produces a fl exing motion in the pelvis. Starting position: Standing. Execution: First pull the iliac crest on one side upward, and then the other side. Note: Athlete fl exes lower back sideways. 128 Chapter 8

Box 8.2 Stability exercise program

Stability with knee and underarm support Support on one arm, sideways Starting position: Standing on all fours, supporting the body on Starting position: Lie on side with legs straight and support the knees and underarms. body on a straight arm. Attach other arm to hip. Place one foot Execution: Maintain position. slightly in front of the other. Note: Discontinue exercise when “tremors” or deviation from Execution: Keep the body straight and the back in the mid-position occur. mid-position. Note: Discontinue exercise when “tremors” or deviation from mid-position occur. Progression: Feet are placed one on top of the other. Same exercise as above.

The plank—Stability with knee and underarm support Starting position: Standing on all fours, supporting the body on toes and underarms. Execution: Maintain position. Note: Discontinue exercise when “tremors” or deviation from Unstable—Foot and underarm support mid-position occur. Starting position: Standing on all fours supporting the body on feet and underarms. Feet and underarms on balance mats. Execution: Maintain position. Note: Discontinue exercise when “tremors” or deviation from mid-position occur.

“Wheelbarrow,” without additional motion Starting position: Athlete assumes same starting position as for push-ups. Assistant grabs athlete’s ankles and lifts. Throughout the execution of the exercise the athlete maintains the same position of the hands. Stability with rotational element—Foot and underarm Execution: Assistant tries to push the athlete gently forward support and then pulls the athlete gently toward himself. The athlete Starting position: Standing on all fours supporting the body on maintains the same curvature of the back and the same feet and underarms. position of the hands. Execution: Move one leg out to the side and back. Note: Discontinue exercise when “tremors” or deviation from Note: Discontinue exercise when “tremors” or deviation from mid-position occur. mid-position occur.

(Continued) Preventing low back pain 129

Box 8.2 (Continued)

Body lift with shoulder support Starting position: Lying on back with arms to the side. Assistant is one step away in front of the athlete. Assistant holds on to athlete’s ankles and lifts to hip height. Execution: Lift buttocks to back mid-position. Only shoulders, neck, head, and arms are in contact with the ﬂ oor. Assistant lets go off one leg. Move leg to the side. Maintain same low back position. Note: Discontinue exercise when “tremors” or deviation from mid-position occur.

The plank—unstable platform with rotation Starting position: Standing on all fours supporting body on feet and underarms. Arms supported on balance cushions. Execution: Move one leg to the side and back. Maintain position. Note: Discontinue exercise when “tremors” or deviation from mid-position occur.

The plank—unstable platform Starting position: Standing on all fours supporting the body on feet and underarms. Hands and feet supported on balance cushions. Execution: Move one arm to the side and back. Maintain position. Note: Discontinue exercise when “tremors” or deviation from mid-position occur.

more muscle fi bers than if the same exercise is surfaces, increasing the load with longer balance done on a stable surface. arms, and by introducing rotational elements. If an athlete is experiencing diffi culty with stabil- When training stability, the athlete should main- ity exercises, the problems may be due to several tain the exact natural mid-position of the lumbar causes: (1) Insuffi cient muscle strength for effective region and pelvis. The athlete is ready to progress to stabilization. If the athlete is not strong enough, the next level when he is able to maintain this posi- it is necessary to, in addition, engage in targeted tion for 20–30 s without “tremors” or deviations. dynamic strength training of muscle groups that This may seem paradoxical, but it is important are too weak. Suggested exercises are described that the athlete tries to execute the exercises as under “Dynamic strength training.” (2) Insuffi cient relaxed as possible. Good stability must not be neuromuscular control. If this is the problem, it confused with a static and restricted execution of may be due to a lack of awareness of which muscles the exercises. are necessary to activate for effective stabilization. If fi nding the neutral mid-position is diffi cult, it may Dynamic strength training of the muscles in the be necessary to focus on awareness exercises fi rst. abdomen and back (Box 8.3) Athletes often experience rapid progress in stability training. It is important to increase the degree of Dynamic strength training has two main objectives: diffi culty, so that the athlete continues to be chal- 1. Increasing the strength in the muscles in the lenged This can be done by introducing unstable abdomen and back. 130 Chapter 8

Box 8.3 Dynamic strength exercises. In most exercises the athlete should aim to execute the movements as explosively as possible in the concentric phase. To increase muscle strength we recommend ϳ10 repetitions in each series, for 3–5 series. To improve muscle endurance the athlete may opt to work less explosively with more repetitions in each series. The execution of the exercises should be pain free.

Buttock lift Sit-ups with fi xed foot position and rotation Starting position: Lying on back with hip and knees bent at 90º Starting position: Lying on back with bent hip and knees. Arms angles. Hands behind head. across chest. Feet on fl oor. Assistant holds athlete’s ankles. Execution: Lift knees toward ceiling, lifting buttocks from the Execution: Lift torso toward thighs, combined with elbow to knee. fl oor. Avoid pulling thighs toward chest, this makes the exercise easier.

Throwing sit-ups Starting position: Lying on back with straight hip and knees. Assistant standing ϳ1.5 m from athlete’s feet. Assistant holding Sit-ups, oblique abdominal muscles, unstable medicine ball. Starting position: Lying partly on the side, with left buttock on Execution: Assistant throws medicine ball toward athlete’s chest. ﬂ oor. Slightly bent hip and knees. Arms rotated toward the right Athlete initiates sit-up motion toward ball, and catches it right side. before it reaches the chest. Continues the motion up to a sitting Execution: Pull arms toward the right side, and lift torso as with position and throws the ball to the assistant before he reaches sit-ups. Change sides and repeat exercise. the sitting position. Exercise is repeated from starting position.

Sideways throwing Oblique abdominal muscles, from below Starting position: Sitting ϳ1 m from assistant. Side facing Starting position: Lying on back. 90º bend in hip and slightly assistant. Bent hip and knees. Thighs and calves not touching bent knees. Legs together. Arms to the side. ﬂ oor. Holding a medicine ball. Execution: Move legs diagonally to ﬂ oor and back. Maintain mid- Execution: Throw medicine ball sideways to assistant. Exercise position in lower back! Repeat exercise on other side. is to be executed explosively.

(Continued) Preventing low back pain 131

Box 8.3 (Continued)

Diagonals Execution: Move pelvis toward ﬂ oor and then back to starting Starting position: Standing on all fours. position. Execution: Bring left hand together with right knee. Then extend Progression: Place feet one on top of the other. Same procedure arm and leg diagonally to a horizontal position. Repeat exercise as above. for opposite diagonal.

Maximal throwing Sideways pelvis lift Starting position: Standing, facing a wall. Holding medicine ball. Starting position: Lie on the side supporting the body on one Execution: Bending knees with an explosive motion, concluding arm. Attach the other arm to hip. Place one foot slightly in front with throwing the medicine ball against the wall. of the other. Note: Lean forward with lower back in mid-position.

2. Normalizing any “weak links” uncovered than slow-twitch fi bers. In order to activate the during the execution of the stability exercises. highest possible number of motor units, it is criti- Exercises focusing on the lower parts of the abdo- cal that the athlete attempts to execute the motion men and back are particularly important. In order as fast as possible. The same principles apply to to be able to tolerate the loads athletes are exposed the muscles in the abdomen and back. However, to, good muscle strength, and muscle endurance for this region one must consider both anatomi- in these regions are important. Increased muscle cal and mechanical factors in order to avoid excess strength results from two mechanisms: strain and injuries resulting from the exercises 1. Muscle fi ber hypertrophy, that is, increasing themselves. the cross-sectional area of the muscles. Many atheletes have problems achieving the 2. Nervous adaptation, that is, activating intended strength increase in the lower part of the more muscle fi bers, faster activation and more abdominal muscles. This may be due to the fact simultaneous activation. that many atheletes worry about injuring their When a new strength exercise program is started, back during exercises intended to strengthen the the initial strength increase over the fi rst few weeks muscles in their abdomen and back. Therefore, is almost exclusively due to nervous adaptation. they are cautious during abdominal exercises, tak- Hypertrophy occurs later, and in order to maximize ing particular care not to activate the hip fl exors. hypertrophy, sub-maximal loads (60–90% of maxi- What appears to be the most common abdominal mal load) with 8–12 repetitions in several series exercise is the “sit-up” without securing the legs, (often 4–6) until exhaustion is recommended. lifting the shoulder blades off the ground. This Movements are performed relatively slowly, partic- exercise does not suffi ciently challenge the mus- ularly in the eccentric phase. cles of the abdomen, back, and hip area, and this Increased muscle strength based on nerv- particular area requires a strong muscle corset. The ous adaptation occurs when several muscle fi b- exercise program suggested in Box 8.3 emphasizes ers are activated simultaneously, particularly the working both the upper and the lower part of the fast-twitch fi bers, which are harder to activate abdominal muscles. 132 Chapter 8

Secondary prevention important to avoid extreme bending movements of the spine in sports whenever possible. In terms of secondary prevention, a certain Competition programs should also take the age of amount of new knowledge has emerged, which the athletes into account. should be implemented. Studies have revealed a The amount of training is of fundamental connection between changes in neuromuscular importance to reduce and avoid overuse injuries control mechanisms and back problems. Changes on the spine in athletes. The young athletes ought in the recruitment patterns for both abdominal to concentrate on coordination, techniques, and and back muscles are apparent in most back pain balance before the growth spurt. Including spe- patients, irrespective of the cause of the prob- cifi c exercises to improve awareness, core stability lems. Muscular dysfunction in low back pain has training, and dynamic strength of the low back, been described for both the deep and the super- abdomen, pelvic, and hip region is highly rec- fi cial muscle systems. Locally, it is expressed as a ommended. In particular, athletes with a history dysfunction in the recruitment and control of of back pain should be targeted with rehabilita- deep segmental stabilizing muscles (Hides et al., tion training concentrating on technique, fl ex- 1996; Hodges & Richardson, 1996; O’Sullivan ibility, and muscle control to withstand the high et al., 1997; Jull & Richardson, 2000). Dysfunction demands of their sport. in the local muscle system in low back pain patients has been shown to include segmental atrophy of deep layers of the lumbar multifi dus References muscles on the painful side (Hides et al., 1994). This appears soon after acute low back pain, and will not automatically normalize when pain sub- Alexander, J. (1977) Scheuermann’s disease. A traumatic sides. Studies have also found delayed recruitment spondylodystrophy? Skeletal Radiology 1, 209–221. and changed function of the transverse abdominis Badman, B.L., Rechtine, G.R. (2004) Spinal injury muscles in persons with lower back pain. considerations in the competitive diver: a case report and review of the literature. The Spine Journal 4, Some studies show good effects on lower back 584–590. pain from targeted exercises of the muscular sup- Bahr, R., Andersen, S.O., Løken, S., Fossan, B., Hansen, T., port system in the lumbar vertebral column, Holme, I. (2004) Low back pain among endurance including the transverse abdominis, lumbar multi- athletes with and without specifi c back loading—a fi dii, and pelvic fl oor muscles. The aim is to isolate cross-sectional survey of cross-country skiers, rowers, the function of these muscles, creating a stabiliz- orienteerers, and nonathletic controls. Spine 29, ing “corset” of “deep stabilizing muscles.” This 449–454. Baranto, A., Hellström, M., Nyman, R., Lundin, O., has proven to be benefi cial both in the short and Swärd, L. (2006) Back pain and degenerative in the long run in terms of improved function and abnormalities in the spine of young elite divers: a 5- decreased pain, and such training is probably criti- year follow-up magnetic resonance imaging study. Knee cal to avoid reinjuries in athletes with a history of Surgery Sports Traumatology and Arthroscopy 14, 907–914. low back pain, although this hypothesis has not Bartolozzi, C., Caramella, D., Zampa, V., Dal Pozzo, G., been tested in formal trials. Tinacci, E., Balducci, F. (1991) The incidence of disk changes in volleyball players. The magnetic resonance fi ndings. La Radiologica Medica 82, 757–760. Take-home message Bono, C.M. (2004) Low-back pain in athletes. Journal of Bone and Joint Surgery (American) 86, 382–396. It is important to be aware of the weakness of Goldstein, J.D., Berger, P.E., Windler, G.E., Jackson, D.W. the growing spine and the relation to the growth (1991) Spine injuries in gymnasts and swimmers. An epidemiologic investigation. American Journal of Sports spurt. To prevent spinal injuries the most impor- Medicine 19, 463–468. tant factor is to avoid high loads on the spine of Hellström, M., Jacobsson, B., Swärd, L., Peterson, L. athletes before the spine is fully grown, which (1990) Radiologic abnormalities of the thoraco-lumbar means at least until after the age of 18. It is also spine in athletes. Acta Radiologica 31, 127–132. Preventing low back pain 133

Hides, J.A., Stokes, M.J., Saide, M., Jull, G.A., Cooper, D.H. Ranson, C.A., Kerslake, R.W., Burnett, A.F., Batt, M.E., (1994) Evidence of lumbar multifi dus muscle wasting Abdi, S. (2005) Magnetic resonance imaging of the ipsilateral to symptoms in patients with acute/ lumbar spine in asymptomatic professional fast subacute low back pain. Spine 19, 165–172. bowlers in cricket. Journal of Bone and Joint Surgery Hides, J.A., Richardson, C.A., Jull, G.A. (1996) Multifi dus (British) 87, 1111–1116. recovery is not automatic following resolution of acute Sassmannshausen, G., Smith, B.G. (2002) Back pain in fi rst episode low back pain. Spine 21, 2763–2769. the young athlete. Clinical Sports Medicine 21, 121–132. Hodges, P.W., Richardson, C.A. (1996) Ineffi cient Swärd, L., Hellström, M., Jacobsson, B., Peterson, L. muscular stabilization of lumbar spine associated (1990) Back pain and radiologic changes in the with low back pain. A motor control evaluation of thoraco-lumbar spine of athletes. Spine 15, 124–129. transversus abdominis. Spine 21, 2640–2650. Swärd, L., Hellström, M., Jacobsson, B., Nyman, R., Jackson, D.W. (1979) Low back pain in young athletes: Peterson, L. (1991) Disc degeneration and associated evaluation of stress reaction and discogenic problems. abnormalities of the spine in elite gymnasts. A American Journal of Sports Medicine 7, 364–366. magnetic resonance imaging study. Spine 16, 437–443. Jull, G.A., Richardson, C.A. (2000) Motor control problems in patients with spine pain: a new direction for therapeutic exercise. Journal of Manipulative and Physiological Therapeutics 23, 115–117. Further reading Kujala, U.M., Taimela, S., Erkintalo, M., Salminen, J.J., Kaprio, J. (1996) Low-back pain in adolescent athletes. Medicine and Science in Sports and Exercise 28, 165–170. Adams, M., Bogduk, N., Burton, K., Dolan, P. (2002) Lundin, O., Hellström, M., Nilsson, I., Swärd, L. (2001) The Biomechanics of Back Pain. Churchill Livingstone, Back pain and radiological changes in the thoraco- Edinburgh. lumbar spine of athletes. A long-term follow-up. Bogduk, N.L.T. (1997) Clinical Anatomy of the Lumbar Scandinavian Journal of Medicine and Science in Sports 11, Spine and Sacrum, 3rd edn. Churchill Livingstone, New 103–109. York. O’Sullivan, P.B., Phyty, G.D., Twomey, L.T., Allison, G.T. Richardson, C., Hodges, P, Hides, J. (2004) Therapeutic (1997) Evaluation of specifi c stabilising exercise in Exercise for Lumbopelvic Stabilization: A Motor Control treatment of chronic low back pain with radiological Approach for the Treatment and Prevention of Low Back diagnosis of spondylolysis and spondylolisthesis. Spine Pain. Churchill Livingstone, Edinburgh. 15, 2959–2967. Chapter 9 Preventing shoulder injuries Michael R. Krogsgaard1, Marc R. Safran2, Peter Rheinlænder and Emilie Cheung3

1Department of Orthopedic Surgery, Copenhagen University Hospital Bispebjerg, Denmark 2Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA 3 Department of Orthopaedic Surgery, Clinic for Physiotheraphy, Frederiksberg, Denmark.

an incidence of 6.4 injuries per 100 participants Epidemiology of shoulder injuries in over a 1-year period. In tennis, the general annual sports incidence of shoulder pain and injury has been estimated at 2.5 injuries per 100 people playing per Shoulder injuries are common in sports and can year, with 3.3% of all tennis injuries involving the be traumatic, microtraumatic, or overuse in origin. shoulder (#7 of all musculoskeletal injuries in ten- Detailed information on the prevention of shoul- nis). The prevalence of shoulder pain in competitive der injurie is lacking, however. According to a study junior tennis players was found to be 24% in boys in the United States, of the general population, and 35% in girls over a 3-year study. Further, it has shoulder injuries accounted for 8.1% of all sports been found that 50% of expert players had a his- injuries. Of these, 9.4% precluded participation on tory of shoulder pain and 74% of professional male at least one occasion, 5.7% precluded participation tennis players and 60% of professional female ten- for at least 1 month, and 10.7% resulted in the par- nis players had shoulder or elbow pain that affected ticipant giving up the sport permanently. Therefore, their tennis at some point in the past. the potential to prevent shoulder injuries should be Swimming is another sport where shoulder pain optimized, and some chronic overuse-related inju- is so prevalent that the term “swimmer’s shoulder” ries, as well as acute injuries, may be avoided. has become commonly accepted, though the exact Table 9.1 provides an overview of available epi- pathology may be argued. It has been shown that demiological data on shoulder injuries in sports. the longer one swims, the higher the prevalence Baseball and softball account for the highest per- of shoulder pain and swimming intensity and centage of shoulder injuries, relative to other distance are most associated with shoulder pain. locations in the body, and these tend to be overuse Studies have shown that the prevalence of shoul- injuries. In the United States, it has been estimated der pain increases with age. In a study of age group that 18% of all injuries in baseball to people over national level competitive swimmers, it was found 6 years of age who play are to the shoulder, second that 11% of male and 9.4% of female competitive only to elbow injuries. It is estimated that 5.8 shoul- swimmers, aged 13–14 years had current shoulder der injuries occur per 100 participants a year. In pain that interfered with their training, while 21% softball 17.4% of all injuries involve the shoulder, of male and 25.5% of female competitive swim- making it the most common injury location, with mers aged 15–16 years had pain at the time of questioning that interfered with their swimming, and 17.7% of male and 35% of female swimmers Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing with an average age of 19 years had shoulder pain ISBN: 9781405162449 limiting their swimming practice and competition.

134 Preventing shoulder injuries 135

Table 9.1 Risk of shoulder pain in different sports. The numbers reported are estimates based on the studies available.

Sport Competition Training incidence1 Rank2 Comments incidence1

Team sports Water polo 3.40** # 1 College players 8.09** Volleyball 0.32* 0.33* # 4 College players 0.2 / # 5 overall Dutch 2nd and 3rd divisions; did # 2 overuse injury not report match versus practice shoulder injury rate

Baseball 0.81* 0.37* # 1 College players Softball 0.24* 0.30* # 5 American football 3.92* 1.63* # 3 College athletes Lacrosse 1.56* 0.23* # 5 College athletes Ice hockey 3.32* 3.92* # 3 College athletes 1.58* 3.92* Individual sports Tennis 5.18** # 4 in women’s tennis, College athletes 7.22** # 1 in men’s 3.89** 1.56 ** High school athletes 9.9 ** # 3 National championships for 15–18 years old 18.4 ** # 1 National championships (girls 19.0 ** 15–16 years old, boys 15–18 years old)

Swimming 6.55 ** # 1 College swimmers 21.05** Wrestling 3.73* 0.47* # 3 College athletes

1Incidence is reported for adult, competitive athletes as the number of injuries per 1000 hours of training and competition or *per 1000 athletic exposures or **per 100 participant years. 2Rank indicates the relative rank of shoulder injuries within the sport in question.

Even more striking is the prevalence of shoulder Ice hockey and American football are the next pain, current or past, in these swimmers; 55% of two sports with very high incidences of shoul- male and 38% of female national age group swim- der injuries, and these tend to be traumatic in mers (13–14 years old) had a current or past his- origin — contact with the ground (ice, turf, or tory of shoulder pain, whereas 67% of male and grass) or boards (hockey) or opponent. In foot- 64% of female competitive swimmers had a cur- ball, shoulder injury was the fourth most common rent or past history of shoulder pain that inter- injury at the National Football League combines fered with their swimming, and 71% of male and (the preparticipation examinations), where 50% 75% of female national team swimmers had pain, of the players had a history of shoulder injury currently or in the past, that interfered with their and there was an average of 1.3 shoulder injuries swimming. Collegiate and master swimmers have reported per player. Acromioclavicular joint injury been reported to have a 50% prevalence of shoul- was most prevalent (41%), with anterior instabil- der pain that lasted more than 3 weeks. ity (20%), rotator cuff injury (12%), clavicle frac- Water polo is a sport that combines swimming ture (4%), and posterior shoulder instability (4%), and throwing, particularly throwing without being the other common injuries reported. In a the benefi t of the full kinetic chain, which may 14-year study of the prevalence of injury at the account for a high prevalence of shoulder pain. NFL combines, acromioclavicular joint injury was 136 Chapter 9 the fi fth most commonly reported injury (15.7 per acute injuries. The intrinsic factors refer to growth 100 players) and shoulder instability was the ninth and anatomic alignment, which are not very easy most prevalent injury (9.7 per 100 players). to control, but also include the muscle-tendon Sports like body building and weightlifting unit, balance, fl exibility, ligamentous laxity, con- may cause repetitive microtraumatic injury of the ditioning and anatomic variations (Table 9.2). The acromioclavicular joint, resulting in osteolysis of strength and fl exibility of tissues and potential for the distal clavicle (weight lifter’s shoulder) with adaptation to external loads are also dependent on prevalence estimated at 27%. age and probably gender. In terms of extrinsic factors: training errors, including throwing mechanics, overuse, environment, and equipment play a Key risk factors: how to identify signifi cant role (Table 9.2). athletes at risk

Age Scientiﬁ cally, little is known about the factors that lead to the majority of injuries in the shoulder. Consequ- Overload problems are more common with increas- ently, the description of key risk factors is based, ing age, for example, the incidence of shoulder to some extent, on theoretical assumptions. pain in baseball players is 0.7% in youth, 12.7% in Intrinsic factors and extrinsic factors both con- college players, and 13.9% in professionals. On the tribute to overuse injuries, and to a limited extent, other hand young baseball players are more likely

Table 9.2 Internal and external factors for shoulder injury in different sports. The numbers reported are average estimates based on the studies available.

Risk factor Relative risk1 Evidence2 Comments

Internal risk factors Previous injury NA 0 Age NA ϩ Overuse, such as length of time participating may be a confounding factor Gender NA 0 Posterior capsular NA ϩ Cadaveric, biomechanical data tightness Crowding of the NA ϩ coracoacromial arch Weakness of scapular NA 0 (Su et al., 2004; Kibler & Safran, 2005; stabilizers and core Laudner et al., 2006; Tripp et al., 2007) Ligamentous laxity NA ϩ Conﬂ icting results External risk factors Mechanics of sports NA ϩ bases NA ϩ Type of sliding Break-away bases Position 1.2–1.52 ϩϩ Overuse NA Number of pitches thrown 1.77–3.29 ϩϩ Type of pitch 1.52–1.77 ϩ Years weight lifting NA ϩ Hours swimming NA ϩϩ

1Relative risk indicates the increased risk of injury to an individual with this risk factor relative to an individual who does not have this characteristic. A relative risk of 1.2ϫ means that the risk of injury is 20% higher for an individual with this characteristic. NA: Not available. 2Evidence indicates the level of scientifi c evidence for this factor being a risk factor for ankle sprains: ϩϩ— convincing evidence from high-quality studies with consistent results; ϩ—evidence from lesser quality studies or mixed results; 0—expert opinion without scientifi c evidence. NA: Not available. Preventing shoulder injuries 137 to have upper extremity injury. The length of time a relatively high risk of suprascapular nerve injury, while participating may also be a confounding fac- which may be related to posterior capsular tight- tor, as seen in weight lifting and swimming, where ness of the shoulder, but also may be affected by a a cumulative effect over the years of overuse seems narrow suprascapular notch or bony change of the to be a reason for injury. transverse scapular ligament. Posterior capsular Some age-related anatomical variations are also tightness of the shoulder has also been implicated risk factors. For example, growth-plate-related in other problems such as internal impinge- problems in the proximal humerus of young ment and SLAP lesions (an injury to the superior baseball players, also known as “Little Leaguers labrum, anterior and posterior to the biceps ten- Shoulder,” have been associated with the repeti- don anchor/attachment—essentially, an injury to tive action of throwing. The forces caused by the the upper part of the fi brocartilage rim that sur- repetitive throwing cause fragmentation and avul- rounds the socket of the shoulder), as well as sec- sion of the growth plate, resulting in shoulder ondary impingement. pain. Improper pitching mechanics have also been identifi ed as a concomitant risk factor for devel- Passive stability opment of this condition. Thus, both intrinsic factors, such as the growth plate being the weak- There is confl icting evidence regarding gleno- est link in the musculoskeletal system, combined humeral laxity as a risk factor for shoulder injury with overuse and improper pitching mechanics, or pain. About 15% have an in born laxity (known which are extrinsic forces, may coexist to produce as multidirectional), but anterior laxity is often injury. seen in overhead athletes due to chronic overload. Excessive repetitive external rotation during the Gender overhead motion places tremendous stress on the anterior capsular and ligamentous structures, causing There are no available data to identify gender as microtrauma. Instability results when the dynamic an independent risk factor for shoulder problems. stabilizers, such as the rotator cuff and periscapular muscles, fatigue with repeated activity. Hence Anatomical factors anterior glenohumeral translation occurs, with subsequent development of instability. Some sports, Overcrowding of the subacromial space, for exam- like swimming, select for individuals who have ple, if the acromion has a hooked shape or if the inherent ligamentous laxity about the shoulder, as acromioclavicular joint is degenerated and hyper- proper swimming mechanics require extreme range trophic, protruding into the subacromial space, of shoulder motion. With repetitive motion, such is a risk factor for outlet impingement (pinch- as prolonged swimming, the muscles that provide ing of the rotator cuff between the bones of the dynamic stability to the shoulder may fatigue, result- humerus and acromion). The precise contribu- ing in microinstability. The rotator cuff fatigues as a tion of this factor in athletes is diffi cult to weigh, result of having to work harder to maintain gleno- as many competitive conditions that can cause humeral stability (due to the lax ligaments) and impingement may be present. For instance, over- overuse from repeated activity (swim strokes). The head athletes, such as those involved in baseball, rotator cuff fatigue leads to decreased ability to main- swimming, water polo, and tennis, often suffer tain the humeral head within the glenoid. As a result from not only tendinopathy or strains of the rota- of this subtle instability, secondary impingement of tor cuff as a result of outlet impingement, but also the rotator cuff anterosuperiorly against the cora- because of cumulative tensile overload, instability, coacromial arch during forward fl exion may occur, as well as with internal impingement (pinching of causing bursitis, tendinitis, or even undersurface the rotator cuff between the greater tuberosity of tearing. Thus, in some sports, rotator cuff damage the humerus and the postero-superior glenoid). may be the result of overuse, pain from muscles Overhead athletes, including volleyball players, fatiguing while trying to provide stability to a shoul- baseball players, and tennis players not only have der with ligamentous laxity as well as due to excessive 138 Chapter 9 translation of the humeral head resulting in impinge- or the clean and jerk, increases the load on the ment. This latter cause of impingement occurs, as the acromioclavicular joint. Whereas rest helps resolve rotator cuff becomes pinched between the humeral the symptoms, return to weight lifting will result head and coracoacromial arch as a result of the loss in recurrence of symptoms. of containment of the humeral head in the center of Also, a high number of pitches is associated with the glenoid due to loss of strength with the fatigued risk for shoulder symptoms. The relative risk in kids rotator cuff muscles. Glenohumeral laxity may well is 1.77 if more than 100 pitches are performed per be a risk factor for these conditions, but the develop- game and 3.29 if more than 800 pitches are done ment of clinical symptoms is also caused by other within a season. The type of pitch is also a risk fac- factors, such as fatigue of the rotator cuff muscles. tor with a relative risk of 1.52 for curve ball and A condition known as “internal impingement” 1.77 for slider. The risk for shoulder problems is of the rotator cuff also occurs as a result of the dependent on player position. In baseball, pitch- altered kinematics in the injured shoulder of an ers are at the highest risk, and in American football, overhead athlete. This occurs as the humeral head quarterbacks have a relative risk of 1.52 and defen- translates anteriorly with shoulder abduction and sive backs of 1.2 for shoulder problems. Also, the external rotation. There is internal impingement injury pattern varies, as anterior shoulder instabil- of the rotator cuff on the posterior superior region ity is common in American football defensive play- of the glenoid labrum. Concomitant posterior cap- ers and posterior instability and rotator cuff injury sular contractures caused by repetitive stress may is seen in linemen. further exacerbate the impingement. This is also known as glenohumeral internal rotational defi cit, Mechanics of sports or GIRD. Athletes typically present with decreased throwing effectiveness and pain, or a “dead arm.” There are well-described mechanical factors that are of signifi cant importance for the risk of trau- Dynamic instability matic injury in baseball. Sliding with the head fi rst as well as dive backs cause more shoulder injuries It is well described that athletes with shoulder than other techniques. The power in the collision pain have weakness of the scapula stabilizing mus- with the base is correlated to the severity of injury, cles (serratus anterior and trapezius) and bad core and the use of breakaway bases instead of traditional stability. It is generally assumed that scapulotho- solid bases reduces this power and the risk for injury. racic instability is a risk factor for shoulder pain, including dynamic (secondary) impingement. On Identifying athletes at risk of injury the other hand it has been shown that pain causes signifi cant changes in muscular coordination by Screening athletes for risk of shoulder problems can inhibiting muscular activity, so it is still an open be done at the beginning of or at any time during question which risk factor came fi rst. the season. The reason to repeat the screening at intervals is that mismatch in muscle coordination External factors: exposure to load may develop during training, even though it was not present at the start of the season. For instance, it has The total exposure to load (years of weight lifting, been shown there is a slowing in conduction veloc- hours of swimming) is a risk factor for degenera- ity of the suprascapular nerve in baseball pitchers as tive and infl ammatory conditions. For example, the season progresses, though the players remained weight lifter’s shoulder is a problem of the distal asymptomatic. Further, it has been shown, that vol- clavicle, where there is osteolysis or bony resorp- leyball players with shoulder pain have a depressed tion. The pathophysiology is unknown, but felt and lateralized scapula and tightness of the posterior to be due to microtraumatic overuse, resulting in capsule and posterior muscles (Kugler et al., 1996). It a stress reaction of the acromioclavicular joint. can, of course, be questioned whether these changes Weight lifting, such as doing the bench press are the cause of pain or the result of pain. Preventing shoulder injuries 139

Table 9.3 Screening tests to identify risk factors for shoulder symptoms in athletes.

Test Comments

Inspection of stature An increased thoracic kyphosis leads to a downward-anterior position of the acromion, which reduces the subacromial space and increases risk of impingement. Cervical lordosis increases posterior compression and the risk of compression to the C5 and C6 nerve roots, and may lead to referred pain in the shoulder region (Figure 9.6). Inspection of resting position of the Protrusion of more than 1/3rd of the humeral head anterior to the acromion stresses the anterior arm shoulder capsule and may be caused by a tight posterior capsule or contract outward rotating muscles. Inward rotation of the arm is caused by dominant pectoralis major and minor and latissimus dorsi muscles and reduces the subacromial space, increasing risk of impingement. Inspection of the resting scapula Winging as well as when the superior, medial corner is more lateral than the inferior, reduces the subacromial space, increasing risk of impingement. Inspection of the moving scapula If the inferior corner of scapula does not reach the mid-axillary line during full ﬂ exion of the arm, the acromion is not elevated sufﬁ ciently during motion, increasing the risk of impingement. If winging occurs early during arm push-ups there is mismatch in muscular coordination. If it occurs late during repeated push-ups, there is weakness of some of the scapular stabilizing muscles. Testing glenohumeral laxity Objective laxity is tested by the sulcus test, the load and shift test, and the posterior stability test. Subjective laxity is tested by the apprehension and relocation tests. Difference in laxity between the two sides indicate pathology and risk of secondary impingement. Testing scapular dynamic stability Weakness increases risk of overuse problems. (Box 9.1) Testing functional shoulder stability Weakness increases risk of impingement and overuse problems. with the arm in various, relevant positions. Investigator tries to break the position to identify weakness

Even though there are no good data available correction of dysfunctions can prevent overload regarding which conditions that increase the risk problems, this strategy is generally accepted. for shoulder problems, previous injury and symp- The contents of a screening examination are listed toms at present are probably high ranking risk in Table 9.3. A description of the various tests can factors that call for a thorough test of possible be found in other textbooks. Tests for scapular sta- dysfunctions, as described in Table 9.3. Athletes bility are shown in Box 9.1. with an increased laxity in the glenohumeral joint (demonstrated by a sulcus sign) are theoretically Take-home message at risk of injury and should also be tested for dysfunctions, but there is no proof that laxity per se Though, as of yet there is not much scientifi c in a well-trained individual without dysfunctions proof that injuries can be predicted based on phys- or “black holes” is a risk factor. ical examination or prevented by correcting prob- In players without symptoms or recent injury, lems identifi ed on examination, there is hope that the screening concentrates on identifying tradi- correcting some of the above physical examination tional dysfunctions, as described by Caldwell et al. fi ndings may prevent overuse injuries and may (2007). In one-arm dominant sports these dysfunc- enable the shoulder to sustain traumatic incidents. tions usually appear in the dominant arm, and the Athletes should be screened for dysfunctions, as two shoulders should always be compared. Even well at the beginning of the season as during the though there is only little scientifi c evidence on season. Athletes with symptoms or earlier injury whether dysfunctions cause shoulder symptoms are probably at special risk. Abnormalities that are and overload injuries or that identifi cation and identifi ed during screening should be corrected 140 Chapter 9

Box 9.1 Low and high load tests for assessment of scapular stability

Low load test for scapular stability Wall-press test for scapular stability The athlete is standing on all four extremities with the scapula The feet are pressed against the wall. The lumbar spine must be held stable, while rocking forward and backward, as well as from kept neutral. Bend one knee and ﬂ ex the hip to 120º, followed side to side without winging of the scapula. by a 15º extension of the hip. The feet can be positioned at various heights on the wall. Progression is pictured from upper left to lower right.

Side bridge as a dynamic stability test of the scapula muscles The athlete is lying on one side on his elbow, while holding his shoulder, hip, knee, and ankle in line (ϭ maintaining core stability). He lifts his body from the ﬂ oor and keeps his scapula stable without any winging.

prior to participation with the intention of pre- shoulder can therefore damage a large number of venting injury and shoulder symptoms. different structures in and around the shoulder. Traumatic injuries can be divided into direct and Injury mechanisms indirect injuries, depending on according to the position of the arm and the applied force.

Because the shoulder has more motion than any Direct traumatic injuries other joint in the body, it has little bony con- straint to allow for this motion, and the stability Direct injuries are falls or blows directly on the and motion is primarily controlled by muscles and shoulder, most often on the lateral side or the front. soft tissues. Traumatic and overuse injuries to the In most cases, there is a contusion of the soft tissues Preventing shoulder injuries 141

enormous compression force between the opponent and the fence. A similar compression occurs in American football when being tackled. The resulting injury depends on the exact direction of the force and the anatomical structure that is subject to the trauma. If the acromion is hit in a skeletally mature athlete, an injury to the acromioclavicular joint is most likely, if the clavicle is hit a clavicular fracture is likely, and if the upper arm is hit, a proximal humerus fracture is likely to occur. In the older athlete, fracture of the clavicle or the humerus is more likely to happen than dislocation of the acromioclavicular joint, as the bone becomes weaker with age. Acromioclavicular and sternoclavicular joint injury is the result of a lateral force. The brachial nerve plexus can be stretched by a direct blow to the superior side of the shoulder, anterior or posterior sudden, forceful pushes to the shoulder or pulls of the arm, and may lead to a “burner,” that is, diffuse pain of the shoulder and arm, caused by injury of one or several nerves, though usually the upper trunk (Figure 9.2). This typically happens if a player uses the shoulder to butt other players.

Indirect traumatic injuries

Indirect injuries are caused by transmission of force through the arm. Fall on an outstretched, ﬂ exed Figure 9.1. Typical injury mechanism for arm may result in a Bankart-like lesion of the pos- acromioclavicular joint dislocation: fall directly on the terior capsule, but most often in acromioclavicular lateral side of the shoulder joint damage, as the posterior shoulder capsule is very tight and transmits the force to the scapula. The injury after fall on an outstretched, abducted around the shoulder or a hematoma. More severe arm depends on the amount of abduction: below trauma may result in a clavicle fracture, a contu- horizontal a SLAP lesion can occur, above hori- sion or dislocation of the acromioclavicular joint zontal a Bankart lesion/dislocation is more likely (Figure 9.1) or fractures of the upper humerus or (where the labral or cartilage rim injury is in the (rarely) the glenoid. Falls are common in cycling anterior lower quarter of the socket). Fall on (when going over the handle bars) and skiing. Blows extended arm results in a SLAP or Bankart lesion are common in American football (i.e., when a player or an acromioclavicular-joint lesion. A force that gets low and uses the shoulder to take an opponent involves rotation of the arm, that is, blocking a or gets tackled and lands on their shoulder) and throw or falling on a slightly abducted/outwardly ice hockey (when the player hits an opponent or rotated arm with ﬂ exed elbow applies tremendous the boards with the shoulder). Compression hap- force on the rotator cuff and the accelerating mus- pens in ice hockey, when the player skates along- cles. This can be an eccentric or a concentric type side the boards and is hit by an opponent. Because of load and result in a muscle/tendon sprain, rup- of the high velocity, the player is subjected to an ture of a tendon, avulsion of a tendon, or fracture 142 Chapter 9

Figure 9.2. Typical injury mechanisms for “burners:” stretching of the brachial nerve plexus

Subscapularis

Labrum Figure 9.3. Dislocation of the humeral head results in a Bankart lesion (avulsion Labrum of the labrum and the glenohumeral ligaments from the anterior glenoid) at the site of insertion. If the arm is positioned of the arm fail to resist the load, this may cause a behind the shoulder joint, blocking can result Bankart or SLAP lesion or stretching of the anterior in an anterior translation of the humeral head capsule. Incidents that make a sudden, powerful and an injury of the anterior structures of the inward rotation of the arm combined with fl exion glenohumeral joint, typically a Bankart lesion of the elbow necessary, if to avoid an object from (Figure 9.3). This injury mechanism is quite com- hitting the head, can rupture the lateral portion mon in body building/strength training as a result of the coracohumeral ligament (which covers the of an extreme extension of the arms during bench biceps groove between the lesser and greater tuber- press or downward pulls. If the arms are extended cles and holds the biceps tendon in the groove) as to more than 0º during these exercises (i.e., if the well as the upper part of the subscapularis tendon arms are moved behind the shoulder joint), there insertion on the lesser tubercle. This results in a is extreme tension on the anterior structures of the biceps tendon dislocation or subluxation. glenohumeral joint, in particular the labrum and It is the least strong tissue that is damaged dur- glenohumeral ligaments. If the internal rotators ing trauma. In children, the epiphyseal growth Preventing shoulder injuries 143 plates and bones are soft, and avulsions of the condition is easily reversible, if the load is adjusted bony attachment of a ligament or capsule rather to the capacity. than rupture of the soft tissue is more likely to Weight lifting applies enormous forces through happen than in adults with stronger bones. Also the acromioclavicular joint, and swimming applies epiphysiolysis of the greater tubercle or the neck a huge number of rotations in the acromioclavicu- of the humerus can happen. In young and middle- lar joint, both mechanisms resulting in infl am- aged athletes, the soft tissue is usually the weakest. mation and gradually degenerative disease in the In athletes above 60 years the natural decrease in acromioclavicular joint. bone mineral content makes fractures and avul- A very specifi c injury develops because the best sions more likely to happen, but tendons—in par- performance in throwing is achieved if the shoul- ticular the rotator cuff tendons and the long head der is cocked, that is, positioned in full abduction of biceps—also weaken with age, and ruptures can and external rotation (Figure 9.4). This motion is happen after minor trauma or almost spontane- naturally stopped by collision between the under- ously, such as during tennis or badminton. surface of the supra- and infraspinatus tendons and the superior labrum. Repeated collisions with Overuse injuries large force result in fraying of both structures and stretching of the inferior glenohumeral ligaments Overuse injuries can be caused by a repeated, pow- (resulting in glenohumeral instability and second- erful force to a structure through sports (extrin- ary impingement) (Figure 9.5). sic factors). In most cases this is the result of an It is not obvious that repeated use of the rota- increase in training intensity, introduction of a tor cuff in forceful tasks during sports results in new technique, or new equipment, etc. The load wear of the rotator cuff/long head of biceps. Such on soft tissue structures exceeds capacity of the tis- changes may more likely be caused by repeated sue, leading to infl ammation and pain. This acute minor traumas with smaller, partial ruptures.

Figure 9.4. In throwing the arm is taken into full abduction and outwards rotation, which result in internal impingement and applies enormous stress to the anterior shoulder capsule 144 Chapter 9

(a) (b) (c)

Figure 9.5. Mechanism of secondary impingement: the humeral head is elevated and the supraspinatus tendon is compressed (a) Natural situation where the rotator cuff muscles and the passive stabilizers keep the humeral head centered in the glenoid during motion and counteract the proximal pull of the deltoid muscle, allowing for shoulder rotation. (b) and (c) If the dynamic and passive stabilizers of the humeral head fails (due to rotator cuff fatigue), the deltoid muscle pulls the humeral head proximally, resulting in impingement of the rotator cuff between the humeral head and acromion.

Overuse injuries can also be caused by pre- caused by these preexisting conditions are seen in existing, less optimal conditions, or by throwing sports (repeated powerful activities to the dyscoordination/lack of dynamic stability in the shoul- extreme ranges of motion), swimming (repeated der and thoracoscapular junction (intrinsic factors). activities), weight lifting (powerful activities), and Laxity of the glenohumeral joint (which is seen in body building (powerful activities and a risk that 10% of the population, represented as a large sulcus only the accelerating muscles are body built). sign) is compensated for by activation of the rotator cuff muscles, when the athlete is using the arm in Pain activities, which are dependent on stability. If these muscles are not strong enough for this work, then Pain in the shoulder has great infl uence on the either the muscles are overused (resulting in tendo- function of muscles. The activity of the agonist nitis and tendinosis of the tendons and muscle pain) for the painful motion is reduced under dynamic or the humeral head is not positioned correctly dur- conditions, probably as a refl ex-like reaction, and ing the activity (resulting in painful stretching of in some cases the antagonist activity is increased. the glenohumeral ligaments and the capsule). The Also, motion patterns are changed to avoid pain. thoracoscapular junction is the base of the arm. This happens in any painful condition, either after Insuffi cient stability of this is caused by relative weak- a trauma or during overload, leading in itself to ness of the rhomboids and serratus anterior (pressing dyscoordination. In this way, a self-perpetuating the scapula against the thoracic wall), resulting in process may be initiated. compensating, painful dysfunctions in other muscles. Dyscoordination of the scapula in throwing or Protective equipment overhead activities is most often caused by weakness or fatigue of serratus anterior and trapezius—both The use of protective equipment can in some cases muscles are responsible for the elevation of acromion cause injury. It is obvious that if a hard shoulder during overhead activities, and if this motion is protector is used by a player to butt others, it may delayed or insuffi cient, the acromion presses against give rise to traumatic injuries on other players. the humeral head, resulting in impingement of the Protective devices may also give the athlete a sense supraspinatus tendon and infl ammation of the of security, prompting them to play more aggres- subacromial bursa (Figure 9.5). Overuse injuries sively, leading to injury to themselves and others. Preventing shoulder injuries 145

Strangely, the use of wrist guards by snowboarders is connected to an (insigniﬁ cant) increase of injury in elbow and shoulder (Hagel et al., 2005), but the injury mechanism is unknown.

Identifying risks in the training and competition program

In sports with a season, the athletes may be less fi t at the beginning of the season. The smaller muscles (including the rotator cuff muscles) are at higher risk than the larger muscles to lose strength. A mis- Figure 9.6. Different statures. Left: Normal stature. Right: match between the shoulder muscles can often be Extended thoracic kyphosis and protracted shoulder, identifi ed as described earlier, but smaller changes, increased lordosis of the cervical spine that become important with 50 or 100 repetitions, may be diffi cult to demonstrate clinically. due to fatigue. Also, if just one structure is not par- For example, the rotator cuff muscles may fatigue ticipating, the heavy exercises should not be con- after 25 hard throws, whereas the larger muscles tinued. It is common to continue until complete can easily do 100. This mismatch may also occur fatigue, but this leads to a high risk of losing the later during the season, because the larger mus- weaker structures. cles adapt more easily to increasing load. Thoracic That mismatch between muscle groups is com- kyphosis may increase as the shoulders rotate ante- mon was shown in a project, where 2000 m swim- rior and inward due to strong latissimus and pec- mers were tested for scapular stability by wall-push toralis major muscles, and the scapula is rotated ups at several swimming distances. After 500 m downward due to the pectoralis minor muscle, 36% had winging of scapula, after 1000 m this was both decreasing the subacromial space and increas- seen in 79%, and after 1500 m in 93%. ing the risk of impingement. Even though we do not walk on our shoul- It is therefore essential that the training pro- ders, turf changes may affect the risk for shoulder gram contains a balanced amount of exercises all injury. In tennis, the speed and force of the ball through the season. It is not uncommon to con- changes from slow and weak on the relatively soft centrate on maximum efforts in function (strength) outdoor ground, particularly clay surface, to fast and coordination, and only do very demanding and forceful on hard indoor courts. This increases training. This will leave the weaker and smaller the need for strength, fast reaction, precision, and muscles behind. Warm-up, which should start coordination markedly, and if the player has not every training session, activates all structures (mus- prepared for this through training, overuse injury cles, tendons, ligaments, joints) as well as the psy- and traumatic lesions to muscles, tendons, etc. che (concentration and awareness, which should may occur. This is naturally also the case if equip- not be neglected). The structures become ready for ment is changed, for instance, if tension of the maximum work, and the maximum effort training strings in the racket is changed or another type of is suitable after warm-up. All athletes know that tennis ball is used. after having performed maximum training for a while, either some structures fatigue or the athlete loses concentration and awareness. Instead of end- Preventive measures ing training abruptly from the heavy exercises, lighter and easier activities, that all structures and the psyche can participate in, should complete the In theory, there are many ways to prevent trau- training session. In this way, no structure is lost matic and non-traumatic shoulder injuries. Some 146 Chapter 9

Table 9.4 Injury prevention matrix applied to shoulder injury prevention: potential measures to prevent injuries.

Pretrauma Trauma Post-trauma

Athlete Assure glenohumeral and Training status Rehabilitation thoracoscapular stability Falling techniques Avoid “black holes” in muscular Reduce and restructure training performance if shoulder is symptomatic Throwing technique Avoid loading of the arm, while Caution if shoulder is painful it is behind the shoulder Prevent falls: only sport within your own limitations, avoid risks (off piste, skiing in bad snow/weather conditions) Prevent huddling (bicycling) Surroundings Playing rules (forbid body checking, Breakaway bases Emergency medical coverage tearing, or blocking of arm) Soft fences Physiotherapist instruction Equipment Caution if equipment is changed (other Shoulder pads First aid equipment characteristics) Neck roll

of these are listed in Table 9.4. Unfortunately, only sliding or forbidding head-fi rst/diveback sliding) one of these methods has been investigated for is impractical and unsatisfactory to players, and effectiveness. instructional courses regarding injury prevention have proved ineffective (players did not attend) Preventing traumatic injury (Janda, 2003). The only studies on injury prevention in softball are the breakaway base studies Shoulder pads can theoretically spread the force (Janda et al., 1988; Pollack et al., 2005). from an impact over a large area of the body and Injury prevention strategies like protective absorb energy (just like a bicycle helmet). There are equipment, rule changes, preseason and season no studies that prove that this can actually reduce prevention interventions, safety measures, better the number or severity of shoulder injuries caused coaching, education and a social awareness have by direct blows, and hard shoulder pads have the been recommended to reduce sports injuries in drawback that they can hurt other players, partic- children (Demorest & Landry, 2003), but none of ularly if they are used to butt others. In American these strategies have been shown to be effective. football, shoulder pads protect the shoulder, dissi- It has been suggested that extrinsic factors may pating the forces that would otherwise be placed on be positively modifi ed to reduce collision injuries the acromioclavicular joint or the sternoclavicular and falls by using deformable walls and padded joint during an axial load. Proper falling mechanics back stops as well as maintaining fi elds appropri- can also be taught to potentially lessen the direct ately, however this has not been supported in the impact placed across the shoulder joint by learning literature. Another statement modifying intrinsic to roll when landing from a fall, rather than land- risk factors, such as better coaching techniques as ing directly on the shoulder. Cervical orthoses are well as stretching and conditioning programs have used to prevent injury to the neck and the brachial been purported to benefi t players in the preven- plexus (“burners”). In a laboratory setting they can tion of their injuries, though again, this has not be shown to reduce hyperextension of the neck, but been objectively supported in the literature. lateral bending—which is assumed to be a major It has been suggested, that injuries from skiing and cause of nerve injury—is not consistently reduced, snowboarding can be prevented by “interventions and the clinical relevance remains to be proven. in education and technique, conditioning and Head-fi rst and diveback sliding techniques in equipment and environment” (Kocher et al., 1998), baseball and softball can result in upper extremity but this remains to be proven. Koehle et al. (2002) injuries. But changing of techniques (e.g., banning states that skiing injuries to the upper extremity Preventing shoulder injuries 147 can be prevented by proper poling techniques and Table 9.5 Standard shoulder training program. avoidance of non-detachable ski pole retention Prophylactic training of stabilizing muscles: devices, as well as through specifi c programs focused on techniques to prevent falls. A positive effect of • Glenohumeral stability: the rotator cuff muscles • Thoracoscapular stability: the serratus anterior and trapezius these interventions on injury risk remains to be musles proven, though. Neither traditional ski instruction • Training of coordination nor preseason conditioning has demonstrated any • Training of thoracic extension positive effect (Koehle et al., 2002). • Training of the rest of the kinetic chain (core stability, knee Theoretically it would to prevent some traumatic placing training, etc.) Stretching to prevent tightness of: injuries if the athlete only did sports within the • The posterior capsule limits of his/her personal qualifi cations or physical • The rhomboid muscles condition, and avoided risky situations (like skiing • The latissimus dorsi muscle off piste, skiing in bad weather conditions, hud- • The pectoralis minor muscle dling in bicycling, etc.). Also the rules can be used to prevent injury, for example, by forbidding body checking, tearing, or blocking of the arm. and endurance training (less load, where the athlete can perform 20–25 repetitions). The specifi c exer- Preventing overuse injuries cises are shown in Box 9.2. Serratus anterior and trapezius are the muscles The thrower’s paradox is that functional stability that lift scapula during abduction, fl exion, and is a key basis for performance, while at the same throwing, and they are often overruled by, for time performance is dependent of full mobility. example, the levator scapula muscle. The trapezius Therefore stability cannot be achieved by tight- should be trained in order to maintain scapular ness, but relies mainly on muscular coordination stability and mid-thoracic stability of the spine. and strength. The serratus anterior muscle can be trained with To some extent the training programs are the side bridge and wall-press exercises as well. The same for preventing overuse shoulder injuries and serratus anterior and trapezius muscles in addition for treating symptomatic shoulders. The strategy to the other scapular stabilizers are trained with is also the same: training should always address side bridge exercises. all structures and all functions (strength, stability, Balancing a fi t-ball or a racket are two of the most fl exibility, coordination, core stability). In addi- demanding exercises for coordination. Thoracic tion, the athlete is tested for possible risk factors extension is trained by leaning back over the back (as described earlier) and the standard training of a chair or laying on the back on a fi t-ball. Just program is adapted individually to compensate for like it is much more diffi cult to manipulate a heavy “black holes.” In addition, when treating sympto- load if you are standing in loose sand, it is diffi - matic shoulders, the physiotherapist has knowledge cult to make a powerful throw, if the body is not of the condition of the tissues that suffer, and must a strong, supportive basis. Therefore core stability modify the programs further in relation to this. training is also a part of basic shoulder training. The standard training program will typi- Core stability training is part of many of the cally contain the elements listed in Table 9.5. exercises previously described and trains the trans- Traditional body building of muscles that are used versus abdominis muscles, the other abdominal to create power is often not necessary, as strength- muscles (including diaphragm), the multifi des, and ening of these muscles often follows from the spe- a number of other spinal muscles. Core stability is cifi c sports activities. obtained by pulling the umbilicus toward the third The strength of the rotator cuff muscles is trained lumbar segment, fl attening the abdominal wall. either with a rubber band (which is very handy, Strong muscles tend to shorten and change as it can be brought everywhere) or weights. The the resting position of the shoulder. This is also athlete should mix power training (with suffi cient the case with the posterior capsule. To avoid this, weight, that only 6–10 repetitions leads to fatigue) stretching should end all training sessions. 148 Chapter 9

Box 9.2 Training program to prevent shoulder problems

Rotator cuff strengthening exercises Training of the trapezius and the opposite serratus anterior Use a rubber band. The athlete in standing position (keeping muscles core stability) holding a rubber band in his right hand doing In the standing position the athlete ties a rubber band around lateral and medial rotation. The scapula must be held stable and the left foot and holds the other end in the right hand. By the humeral head must be kept from gliding anterior. The elbow elevating his right shoulder, he is training the upper part of must be kept in the scapular plane during exercises. When trapezius (also called Trapezius 1). When ﬂ exing the right arm doing lateral rotation the rubber band comes from inferior and further posterior, he is training the middle and lower parts of when doing medial rotation from behind the athlete at shoulder trapezius (also called Trapezius 2 and 3). At the same time the level. The exercise can be progressed by using a harder rubber left arm and shoulder can grab the rubber band and be pushed band. forward, in order to train the left serratus anterior muscle. During these exercises the thoracic extension can also be trained by lifting the sternum. The lumbar spine must be kept stable.

Training of the serratus anterior and trapezius muscles The athlete is sidelying on his right elbow maintaining core and scapular stability, holding his left arm in 90º of ﬂ exion/ abduction while rotating his body and reaching as far as possible. The exercise can be progressed by holding a weight in the left hand.

(Continued) Preventing shoulder injuries 149

Box 9.2 (Continued)

Training of coordination with a racket Training of thoracic extension II The athlete in standing position is balancing a racket on one The athlete is lying on his back on a ﬁ t-ball with his arms over ﬁ nger without moving his feet and constantly changing the the head rocking forward and backward, mobilizing the thoracic position of the arm. Exercise should be performed for 3 min. spine in passive extension.

Training of thoracic extension III Athlete sitting on a chair leaning backward over the back of the chair mobilizing the thoracic spine into extension.

Training of coordination with a fi t-ball The athlete laying on the fl oor balancing a fi t-ball on his hand while changing position of the arm into fl exion/extension and abduction/adduction. Exercise should be performed for 3 min.

Stretching of the posterior capsule and outward (lateral) rotators The athlete is side-laying with his right arm in 90º of ﬂ exion. The left arm presses the humeral head posterior and inwardly Training of thoracic extension I (medial) rotates the right arm at the same time. Each position Athlete standing with his elbows against a wall with his hands should be kept for 40 s. ﬁ ngers placed around a segment of the thoracic spine making extension of the thoracic spine while the lower back is kept stable.

(Continued) 150 Chapter 9

Box 9.2 (Continued)

Stretching of latissimus dorsi, the rhomboids muscles, and inward rotation of the arms, the muscles are stretched. Each other inward rotating muscles position should be kept for 40 s. The athlete is standing in a corner doing wall-slide. By elevating the arms while keeping the scapula stable and not allowing any Stretching of the pectoralis minor muscle The athlete standing in a doorway with his right arm in 180º of ﬂ exion and his elbow against the door-frame, leaning his body forward to stretch the pectoralis minor muscle. Each position should be kept for 40 s.

The elements of this basic, prophylactic training Shoulder problems caused by overloading dur- program can be adjusted depending on the fi nding ing the golf swing can theoretically be prevented of “black holes” in the screening of the athletes. by a warm-up program. Overuse injuries are more Proper throwing mechanics and limiting the common in golfers that do not perform a warm-up number of pitches and innings thrown are crucial program, but the effect of the program has never for prevention of injury, particularly in the grow- been studied in a regular trial (Fradkin et al., 2005). ing athlete. Control, not speed, should be empha- Cushion grip bands have been proven to reduce sized in training regimens. In addition, educating impact shock and vibration transfer in tennis rac- coaches and players about appropriate stretching, quets. This could reduce the load on elbow and strengthening, conditioning, and proper throwing shoulder and positively infl uence the risk for over- mechanics is vital. The literature on this topic has load injuries, but the effect remains to be proven. fortunately resulted in published guidelines that limit the number of innings that young pitch- Strength training ers are allowed to pitch per week. The American Academy of Orthopedic Surgeons recommends In athletes, strength training of the shoulders limiting pitches to about 4 to 10 innings per week, should not be performed without the basic shoul- 80–100 pitches maximum per game, and 30–40 der training program, which is described earlier. pitches per practice session (Tables 10.7 and 10.8). Without the basic program, there is an obvious It has been suggested that certain pitching, bat- risk of creating mismatch between muscles. ting, and fi elding techniques might be related to Strength training can be performed after standard injury, in particular the underarm technique dur- principles as high load (maximum 10 repetitions ing softball pitching (Flyger et al., 2006). This is possible) to increase power or as low load (many based on biomechanical and not clinical studies. repetitions) to increase endurance and fl exibility. Preventing shoulder injuries 151

Moving the arm posterior to the shoulder joint relation to their periscapular and back muscles, (shoulder extension) should always be avoided, resulting in a protracted shoulder posture. This as this is unnecessary to achieve the full effect of also decreases the subacromial space and contrib- strength training and results in potentially inju- utes to outlet impingement syndrome. This may rious large stresses the anterior structures of the be prevented by strengthening the rhomboids and glenohumeral joint. Bench press is typically an scapular retractor muscles. exercise in which the arms are quite often moved behind the shoulders, creating anterior pain in the shoulder. Take-home message The only intervention that has been proven Getting back after shoulder injury effective in preventing traumatic shoulder injury The aim of physical therapy after shoulder injury is is the introduction of break-away bases in softball. to relieve pain, expedite the return of the athlete to Theoretical preventative measures like shoulder play, and most importantly, to prevent new inju- pads, collars, learning falling techniques, forbid- ries before they develop. Stretching is important ding risky playing habits, and softening walls, and to establish and maintain full range of motion, back stops have yet to be proven effective. especially in patients with tight posterior capsules The risk for overload injuries, which are very with limited internal rotation. “Sleeper stretches” common in shoulders, can theoretically be are stretching maneuvers which are effective in reduced if all athletes are screened regularly for stretching the posterior capsule, and prevent inter- weakness in glenohumeral and scapulothoracic nal impingement associated with GIRD. They are stability and for lack of balance between muscles performed with the athlete lying on the affected (identifying dominance of muscles, most often side, with the shoulder abducted 90º. Gentle con- inward rotators of the arm and downward rotators stant pressure is applied by the opposite arm, push- of the acromion). It is recommended that weak- ing the affected shoulder into internal rotation. nesses and dysfunctions are treated by exercise During the acute phase of tendinitis, exercises programs, but the effect of this on injury preven- should be performed below shoulder level to avoid tion remains to be proven. Learning the proper rotator cuff outlet impingement, with gradual pro- techniques in the individual sports is thought to gression as symptoms decrease. In the majority of be important for prevention of overload. cases, non-surgical treatment allows gradual return The growing athlete is at particular risk for over- to sport. load injury, for example, at the growth plates, and A strengthening program is instituted to increase repeated, forceful activities should be reduced, for strength in the rotator cuff as well as in the scapu- example, the number of pitches per game. lar stabilizers to provide dynamic glenohumeral stability. Both concentric and eccentric exercises are included. Improper throwing mechanics also must be corrected. Throwing athletes are allowed References to return gradually to throwing once stability, strength, and endurance have improved (usually Caldwell, C., Sahrmann, S., Van Dillen, L. (2007) Use of within 3 months). Most will be able to return to a movement system impairment diagnosis for physical their prior level of activity in 6 months. therapy in the management of a patient with shoulder Swimmers tend to develop tightness in the pec- pain. The Journal of Orthopaedic and Sports Physical Therapy 37, 551–563. toralis minor, which leads to a protracted shoulder Demorest, R.A., Landry, G.L. (2003) Prevention of posture. This decreases the subacromial space and pediatric sports injuries. Current Sports Medicine Reports contributes to outlet impingement syndrome. This 2, 337–343. may be prevented by stretching the pectoralis minor. Flyger, N., Button, C., Rishiraj, N. (2006) The science Wrestlers tend to strengthen their anterior of softball: implications for performance and injury shoulder and chest muscles disproportionately in prevention. Sports Medicine 36, 797–816. 152 Chapter 9

Fradkin, A.J., Cameron, P.A., Gabbe, B.J. (2005) Golf Further reading injuries—common and potentially avoidable. Journal of Science and Medicine in Sports 8, 163–170. Hagel, B., Pless, I.B., Goulet, C. (2005) The effect Andrews, J.R., Wilk, K.E. (eds.) (1994) The Athlete’s of wrist guard use on upper-extremity injuries in Shoulder. Churchill Livingstone, New York. snowboarders. American Journal of Epidemiology 162, Burkhart, S.S., Morgan, C.D., Kibler, W.B. (2003) The 149–156. disabled throwing shoulder: spectrum of pathology Janda, D.H. (2003) The prevention of baseball and Part I: Pathoanatomy and biomechanics. Arthroscopy softball injuries. Clinical Orthopaedics and Related 19, 404–420. Research 409, 20–28. Burkhart, S.S., Morgan, C.D., Kibler, W.B. (2003) The Janda, D.H., Wojtys, E.M., Hankin, F.M., Benedict, M. disabled throwing shoulder: spectrum of pathology. (1988) Softball sliding injuries: a prospective study Part II: Evaluation and treatment of SLAP lesions in comparing standard and modiﬁ ed bases. Journal of the throwers. Arthroscopy 19, 531–539. American Medical Association 259, 1848–1850. Burkhart, S.S., Morgan, C.D., Kibler, W.B. (2003) The Kibler, W.B., Safran, M.R. (2005) Tennis injuries. Medicine disabled throwing shoulder: spectrum of pathology and Sports Science 48, 120–137. Part III: The SICK scapula, scapular dyskinesis, the Kocher, M.S., Dupre, M.M., Feagin Jr., J.A. (1998) kinetic chain, and rehabilitation. Arthroscopy 19, Shoulder injuries from alpine skiing and 641–661. snowboarding. Aetiology, treatment and prevention. Harries, M., Williams, C., Stanish, W.D., Micheli, L.J. Sports Medicine 25, 201–211. (eds.) (1998) Oxford Textbook of Sports Medicine. Oxford Koehle, M.S., Lloyd-Smith, R., Taunton, J.E. (2002) Medical Publications, New York. Alpine ski injuries and their prevention. Sports Medicine Hawkins, R.J., Misamore, G.W., Huff, T.G. (eds.) (1996) 32, 785–793. Shoulder Injuries in the Athlete: Surgical Repair and Kugler, A., Krüger-Franke, M., Reininger, S., Rehabilitation. Churchill Livingstone, New York. Trouillier, H.H., Rosemeyer, B. (1996) Muscular Jobe, F.W., Tibone, J.E., Pink, M.M., Jobe, C.M., imbalance and shoulder pain in volleyball attackers. Kvitne, R.S. (1998) The shoulder in sports. In British Journal of Sports Medicine 30, 256–259. C.A. Rockwood, F.A. Matsen, M.A. Wirth, & Laudner, K.G., Myers, J.B., Pasquale, M.R., Bradley, J.P., D.T. Harryman (eds.) The Shoulder, pp. 1214–1238. Lephart, S.M. (2006) Scapular dysfunction in throwers Saunders, Philadelphia, PA. with pathologic internal impingement. The Journal of Krogsgaard, M.R., Debski, R.E., Norlin, R., Rydqvist, L. Orthopaedic and Sports Physical Therapy 36, 485–494. (2003) Shoulder. In M. Kjær, M. Krogsgaard, Pollack, K.M., Canham-Chervak, M., Gazal-Carvalho, C., P. Magnusson, L. Engebretsen, H. Roos, T. Takala, & Jones, B.H., Baker, S.P. (2005) Interventions to prevent S.L-Y. Woo (eds.) Textbook of Sports Medicine: Basic softball related injuries: a review of the literature. Science and Clinical Aspects of Sports Injury and Physical Injury Prevention 11, 277–281. Activity, pp. 684–738. Blackwell Science, London. Su, K.P., Johnson, M.P., Gracely, E.J., Carduna, A.R. Sahrmann, S.A. (2002) Diagnosis and Treatment of (2004) Scapular rotation in swimmers with and Movement Impairment Syndromes. Mosby Inc, St. Louis, without impingement syndrome. Practice effects. MO. Medicine and Science in Sports and Exercise 36, Warren, R.F., Craig, E.V., Altchek, D.W. (eds.) (1999) 1117–1123. The Unstable Shoulder. Lippincott–Raven Publishers, Tripp, B.L., Yochem, E.M., Uhl, T.L. (2007) Functional Philadelphia, PA. fatigue and upper extremity sensorimotor system acuity in baseball athletes. Journal of Athletic Training 42, 90–98. Chapter 10 Preventing elbow injuries Mark R. Hutchinson1 and James R. Andrews2

1Department of Orthopaedics, University of Illinois at Chicago, IL, USA 2Medical director, American Sports Medicine Institute, Birmingham, Alabama, USA, Andrews Sports, Medicine Institute, Gulf Breeze, FL, USA

Epidemiology of elbow injuries in falls are considered. When all sports are consid- sports ered in adolescent athletes, the elbow accounts for only 2–5% of all injuries (Table 10.1). In sports that have a higher throwing demand such as base- The elbow is a complex hinge joint that joins the ball the incidence jumps up to 17–70% depend- distal humerus to the proximal radius and ulna. ing on the position, age, and defi nition of injury The joint has two degrees of freedom, fl exion/ (Table 10.1). extension and pronation/supination, which play important roles in most sports by transferring forces between the body core and shoulder to the High energy injuries hand. In addition, the elbow allows the athlete The transfer of large, acute loads risks catastrophic to specifi cally, repetitively, and with a great deal failure of ligaments, tendons, or bone. The most of fi nesse position their hand in space. Excessive common acute traumatic mechanism is a fall on forces leading to injury can come from acute loads an outstretched hand. Acute traumatic injuries as seen in direct trauma and falls or chronic loads are most common in contact and collision sports as seen in overuse and repetitive microtrauma. (American football, rugby, martial arts, etc.), sports that place an athlete at elevated heights (high High demand versus low demand jump, ski jumping, gymnastics, etc.), and high sports energy sports in which the athlete is at a great rate of speed (alpine skiing, speed skating, cycling, etc.). Sports with relatively low upper extremity demand Eight percent of judo injuries, 4% in wrestling, and would be expected to have low risk of elbow inju- 3–4% in ice hockey involve the elbow (Table 10.1). ries; and, indeed, this is true. Soccer (other than In addition, sports such as weight-lifting, boxing, the goalie), track and cross-country, as well as the shot put, and gymnastics place acute and heavy purely jumping sports such as long jump, high loads across the elbow joint during the course of jump, and triple jump have a low risk of elbow participation. In some cases, the force across the injuries. Other sports such as Nordic or Alpine ski- elbow can far exceed the body weight of the gym- ing, equestrian, cycling, speed skating, and fi gure nast, the weight being lifted, or the weight being skating have relatively low risk until high energy thrown. If the loads aren’t balanced appropriately across the joint, catastrophic failure occurs. The differential diagnosis of traumatic injury of the Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing elbow includes: elbow dislocation, radial head dis- ISBN: 9781405162449 location; intra- and extra-articular distal humerus

153 154 Chapter 10

Table 10.1 Risk of elbow injury in different sports. The numbers reported are average estimates based on the studies available.

Sport Competition incidence1 Training incidence1 % of all injuries Rank Comments

Team sports Baseball 0.29* 8.60% Softball 0.17* 4.70% Ice Hockey 0.14* 2.8–4.6% Basketball ( ) 0.06* 1.20%

Basketball ( ) 0.06* 1.10% Football (American) 0.08* 1% Lacrosse ( ) 0.04* 0.70% Lacrosse ( ) 0.03* 0.60% Volleyball ( ) 0.01* 0.5–1.6% Beach volleyball 0.01 1% (14th out of 17) Competition 3 more common than training Soccer ( ) 0.01* 0.5–1.3% Soccer ( ) 0.01* 0.5% Field hockey 0.01* 0.5% Waterpolo 0.02 1%

Individual sports Sailing 0.04 13% (3rd most common) Javelin 0.11 0.03 1.4–6% High risk of DJD at long term follow up Tennis – Club level 2.4 35% – Elite 18 year 1.2 5% Golf – professional 0.06–0.12 5% /7% (2nd most Overuse most common common) – amateur 3 more common 35.5% /32.5% than pros Judo 1.2 7.70% Wrestling 0.39* 4.30% Gymnastics ( ) 0.38* 4.10% Gymnastics ( ) 0.10* 1.90% Karate 0.10 3.80% Weight-lifting (Olympic) 2.50% Boxing 0.5* 1.00% ↑ DJD when retired Mixed martial arts 0.06* 2.10% Paralympic sport – Wheelchair sports 1.5 12% 30–60% related to training – Sled hockey 1 5% Luge 0.39 6–13%

1 Incidence is reported for adult, competitive athletes as the number of injuries per 1000 hours of training and competition or *per 1000 athletic exposures. fracture; physeal injury in the skeletally immature, reduce the risk of catastrophic injuries; nonethe- radial head or neck fracture; avulsion injury of the less, traumatic injuries are the most difﬁ cult to epicondyle, olecranon, or coronoid; distal biceps target with prevention. They also have the greatest tendon rupture; triceps rupture; nerve contusions; risk of leaving residual deformity, loss of function ulnar nerve subluxation; or neurovascular injury. or restrictions in motion, or arthritis, which can In some instances, the rules of participation may lead to permanent disability. Preventing elbow injuries 155

Low energy/overuse injuries to the athlete. Is it possible to identify athletes at risk to be able to target prevention programs? Repetitive subcatastrophic load may cause chronic These factors may be categorized as either inter- overuse or repetitive microtraumatic injury such nal or external infl uences. Internal factors include as tendinopathy, stress fracture, and ligament the unique anatomy of the elbow, age of the par- sprain. Chronic overuse can weaken the native ticipant relative to physeal closure, articular align- structural elements to the extent that normally ment, physical strength, and coordination of the submaximal loads exceed the ultimate strength kinetic chain (Table 10.2). Gender may play a small of the structure and lead to catastrophic failure. role; however, it is more likely that how intensely Repetitive overuse injuries are more common in and how often the athlete uses his elbow is the upper extremity demanding sports that use a rac- greatest risk factor. External factors include such quet or stick (tennis, racquetball, golf, lacrosse, things as the level of play, number or repetitions etc.) or throw an object (javelin, baseball, soft- or throws, amount of rest between competitions, ball, etc.). Nearly 9% of baseball injuries, 7% of risk of contact and collision in a specifi c sport, javelin injuries, 5% of softball injuries, and 3% equipment, environment, and the technical style of tennis injuries involve the elbow (Table 10.1). (form, overhead motion versus side-arm motion, It is in these sports that the elbow’s functional or coordinated progression of the kinetic chain). demand of repetitively placing the hand in space is particularly important. With subtle variations of hand positions the ball or object to be deliv- Young athletes and growing bones ered may end up in a completely unintended The skeletally immature elbow has numerous ossi- location. Failure or dysfunction at the elbow will fi cation centers and growth plates which, regard- lead to poor performance and potentially fur- ing injuries, are the “weak link.” The ossifi cation ther injury at the elbow or adjacent structures. center of the capitellum is at risk of vascular injury Chronic overuse injuries about the elbow include: secondary to repeated compression associated tendinopathy of the extensor carpi radialis brevis with weight-lifting and boxing, the weight-bear- (tennis elbow), tendinopathy of the fl exor mus- ing demands of gymnastics, or the valgus stresses cle insertions (golfer’s elbow), bicipital tendin- associated with throwing (Figure 10.1). On the opathy, cubital tunnel syndrome (ulnar neuritis), medial aspect of the skeletally immature elbow, ulnar nerve instability, pronator teres syndrome the medial epicondylar ossifi cation center serves (median nerve entrapment), stress fractures, oste- as the insertion of the medial collateral ligament ochondritis dissecans, or valgus extension over- and fl exor muscles of the forearm. It is at risk of load syndrome with associated spurring or loose avulsion secondary to the tension forces when the body formation from the olecranon or capitellum. elbow perceives valgus loads such as in weight- Overuse injuries are more common than acute bearing, weight-lifting, or throwing. Isolated ulnar traumatic injuries, and are easier to target regard- collateral ligament injuries are uncommon in the ing injury prevention. In one study of 21 javelin skeletally immature thrower; however, a growing throwers 19 years after sports participation, all fi eld of literature has reported this injury as well as had degenerative changes in their elbow and 50% surgical reconstruction in this population. had loss of extension.

Mature and masters athletes Key risk factors: how to identify athletes at risk For the skeletally mature athlete, chronic changes can occur on the lateral side of the elbow including the creation of bone spurs, radial head hypertro- When making an effort to prevent injuries, it is phy, ﬂ attening and fragmentation of the capitel- important to recognize not only the overall risk in lum which in turn leads to loose bodies. On the a speciﬁ c sport but also any key risk factors relative medial side of the mature elbow, the ulnar collateral 156 Chapter 10

Table 10.2 Internal and external factors for elbow injuries in different sports. The numbers reported are average estimates based on the studies available.

Risk factor Relative risk1 Evidence2 Comments

Internal Risk Factors Prior injury 2 Prior osteochondrosis 2Increased risk of OCD of the elbow in athletes with prior osteochondrosis Alignment – Elbow carrying angle 1 – Developmental glenohumeral ? Unknown correlation with elbow injuries external rotation deﬁ cit (GERD) Skeletally immature 2 Gender (male vs female) 1Males Female likely related to # of participants & sport demands, not gender

External Risk Factors Court surface 1No effect on elbow injury rates Number of throws 3 Number of years of throwing 2Cumulative effect ↑risk over time Throwing style 1Overhand vs sidearm styles – Softball 0.5Windmill style reduces elbow risk Backhand style in tennis 0.5Two ﬁ sted ↓elbow injury risk Type of pitch X Little effect but poorly thrown curveball, – Fast ball vs curveball ↑ risk of injury in the youth Elbow pads 0.5 Tightly strung racquets 2 Oversized racquet heads 0.5 Oversized grips 0.5 Some debate. Probably reduces the tension over the 2 extensor muscle mass which reduces the risk of tennis elbow Wet or heavy balls

1Relative risk indicates the increased risk of injury to an individual with this risk factor relative to an individual who does not have this characteristic. In this chart, standard risk would be 1. The magnifi cation estimates are based on considering a mild increased risk to be 2 and a moderate to signifi cant increased risk to be 3. A mild estimate of reduction of risk would be 0.5 and a moderate to signifi cant risk reduction to be 0.25. 2Evidence indicates the level of scientifi c evidence for this factor being a risk factor for ligament sprains: — convincing evidence from high-quality studies with consistent results; — evidence from lesser quality studies or mixed results; 0 — expert opinion or hypothesis without scientifi c evidence. * Odds ratio and not relative risk. NA: Not available. ligament and not the medial epicondyle is the weak narrowing and peri-articular spurring are more link. Weight bearing on the upper extremity or the commonly seen in older throwers, gymnasts, throwing motion places a tension load across the weight-lifters, and martial artists. ulnar collateral ligament which can lead to injury or failure (Figure 10.2). Masters athletes (older ath- Injury risk builds from the ground up letes) have placed a life-time of wear and tear on their joints and are at greater risk of degenera- Recent focus on elbow injury prevention has tive and overuse problems than the young athlete. looked beyond specifi c anatomic structures of The elevated risk of tennis elbow (extensor carpi the elbow and targeted the effi cient transfer of radialis tendinopathy) in the master’s athlete com- forces from the ground through the body core pared to the younger athlete is well recognized. and shoulder to the elbow in throwing athletes; Chronic degenerative changes including joint space that is, the kinetic chain (Figure 10.3). The health Preventing elbow injuries 157

poor transfer of kinetic forces and overuse of the structures about the elbow. The throwing athlete with poor core mechanics tends to alter their throwing style in an effort to maintain the same throwing velocity. This is often at the expense of ideal shoulder and elbow positioning which places the elbow at an increased risk of injury. A history of shoulder injuries, indeed a history of any injury along the kinetic chain, has been directly correlated to an increased risk of elbow injuries (Table 10.2).

Identifying external risk factors

In addition, a number of external factors play key roles in the incidence of elbow injuries. These Figure 10.1. Valgus load on the skeletally immature elbow external infl uences include how frequently the risk compression of the capitellum and development athlete is asked to use or load the elbow, how of osteochondritis dissecans (solid black arrows) and/or much rest is allowed between events to allow the traction of the medial epicondyle apophysis with possible elbow to recover, certain styles of performance, avulsion (solid grey arrows) as well as the effect of equipment modifi cations including grips, braces, string tension of racquets, and weight or size of a projectile being thrown (Table 10.2). Baseball, a classic throwing sport, and tennis, a classic racquet sport, have been the two Ulnar nerve sports subjected to the greatest scientifi c scrutiny. In baseball, a ball is delivered in an overhand Anterior bundle throwing style at speeds approaching 160 km/h over 100 times in a game. As the athlete fatigues, Posterior bundle he may develop a poor throwing style that does not take advantage of an effi cient kinetic chain Transverse bundle and leads to an increased risk of overuse and injury. Excellent studies are available in the skele- Figure 10.2. Anatomic drawing of the medial elbow tally immature thrower that show that elbow inju- ligaments. Anterior bundle is loaded during the throwing ries including medial epicondyle epiphysitis and motion and is at risk of failure due to tension loads. osteochondritis dissecans are directly associated Reproduced with permission @ Mary Lloyd Ireland M.D., Kentucky Sports Medicine with the total number of pitches delivered per game, per week, and per season (Table 10.2). The same studies reveal that limiting young throw- of the elbow is dependent on coordinated move- ers to a certain number of pitches can reduce the ment, transfer of forces, and health proximally in overall incidence of injury. In addition, when the the kinetic chain. This is particularly true in the young athlete is allowed a period of rest between throwing athlete where poor coordination of the outings, his elbow is allowed to recover and the scapular stabilization muscles (scapular dyskinesia) incidence of injury is further reduced. has been directly correlated with an increased risk Throwing mechanics including specifi c pitch of elbow injuries. Similarly poor coordination of type have also been carefully studied in baseball core muscles including the lumbar spine, abdomi- regarding their relationship to injury risk (Figure nals, and gluteal muscles has been associated with 10.4). Fast balls and change-ups are thrown with 158 Chapter 10

Push off and cocking Acceleration/impact: Follow-through energy storage energy transfer, energy discharge torso/shoulder rotation, elbow extension

Figure 10.3. Optimal throwing or serving technique requires a sequential force transfer from the ﬂ oor up the leg, thru the torso and shoulder to the elbow and hand at delivery; that is, the kinetic chain

the most natural of mechanics and are the pitches Alternatively, the young thrower may try to by which all others are compared. The fast ball explosively supinate their forearm with delivery. has been shown to create the greatest forces These mechanical alterations increase the load across the elbow joint followed by the slider, cur- across the elbow and increase the risk of injury. veball, and change-up. A curveball is thrown by For this reason, throwing the curveball is discour- altering the pitcher’s grip on the seams and by aged in the skeletally immature thrower until repositioning their wrist during the delivery. In nearing skeletal maturity when they can perform a well-thrown curveball, very little mechanical it with proper technique and do not risk their change is perceived across the elbow. However, open growth plates. in a young thrower learning to throw the pitch, In elite level pitchers the side-arm motion has they tend to drop their hand delivering the ball been studied and shown to have very little cor- in a more side-arm motion, they tend to lead with relation with elbow injuries. In a well-thrown their elbow throwing the ball more like a dart. side-arm pitch, the angles and forces across the Preventing elbow injuries 159

Side-arm versus overhand motions: shoulder abduction 90–110°

Figure 10.4. The side-arm motion of delivery is actually just a lateral bend at the torso and not less shoulder adduction shoulder and elbow are nearly identical to the stop being the wrist and elbow. It is, therefore, not overhead motion. The difference occurs in the lat- surprising that longer, rigid racquets with tight eral tilt of the torso in the side-arm thrower. While strings increase the risk of tennis elbow in the ath- this may increase the risk of low back problems, letes that use them (Table 10.2). Increased forces there does not appear to be increased loads across are also seen when players play with wet or heavy the elbow (Table 10.2, Figure 10.4). Windmill style tennis balls. Large headed racquets increase the of pitching seen in softball has very little risk of size of the “sweet spot” which reduces the chance elbow injury. of a miss hit that might cause rotational torque in the forearm. Theoretically this will reduce the risk Risk factors in racquet sports of injury. Grip size has also been associated with injury risk and particularly increased risk of tennis During service, tennis and many racquet sports elbow. A small grip forces the athlete to shorten mimic the overhead throwing motion. Therefore, their fl exors and places the fi nger and wrist exten- athletes in racquet sports can be equally suscep- sors at greater length. This increases the forces at tible to repetitive overuse injuries and failures in the elbow during a backhand or wrist extension the kinetic chain as are athletes participating in maneuver. Larger grips have been used to reduce predominantly throwing sports. The racquet pro- this risk or treat the athlete with an early onset vides an increased extension moment that can of lateral tendinopathy. Recent studies have sug- further load all units of the kinetic chain includ- gested that grip size changes of less than ¼ of an ing the elbow (Figure 10.5). Longer racquets inch have no effect on forearm muscle fi ring pat- increase the load. Tighter strung racquets or more terns. Reduction of the forces along the elbow rigid racquets absorb less shock and transfer the extensors has also been targeted through biome- loads directly up the kinetic chain with the fi rst chanical adjustments in technical style. Two-fi sted 160 Chapter 10

chronic elbow problems. In the skeletally immature elbow these repetitive compressive loads have been directly associated with osteochondritis dissecans of the capitellum, olecranon impingement, and medial epicondylitis (Figure 10.1). The intensity and frequency of loading may place the skeletally mature elbow at risk of degenerative changes of the articular surface or the creation of osteochondral loose bodies. Many master athletes who have participated for many years develop secondary changes and degenerative changes in the lateral and posterior compartments of the elbow. Identifying the athlete at risk of elbow injuries from compressive loading begins with early recognition of complaints and an immediate period of rest. Loading and weight-bearing are inherent to the sports of boxing, gymnastics, and weight-lifting and cannot be eliminated completely.

Take-home message

So which athlete should you keep the closest eye on and plan an early intervention? Surprisingly, the answer is usually the best athlete. He/she is the one who has the most repetitions, creates the Figure 10.5. The racquet increases the distance of the impact of the ball from the elbow. This increased moment highest forces across the elbow, and is likely to be magnifi es the forces felt at the elbow the most intense in training taking minimal periods of rest. Be attentive to faulty mechanics in not only sport-specifi c techniques but also of core strength and stability. Young athletes should be back-hands have been shown to reduce the forces progressive in their skill-building. If performance across the lateral elbow when compared to single- begins to decline, it may be the fi rst sign in the fi sted backhands. development of an overuse injury which should The training location and court surface may indicate initiating a period of rest and recovery. play a minimal role. Court surface in tennis, clay versus grass versus synthetic, does alter ball speeds but has not been directly related to elbow injuries. Likewise ball players on grass versus synthetic turf Injury mechanisms have not been correlated with an increased risk of elbow injuries although falls on synthetic turf lead to more skin abrasions than on natural grass. As noted earlier, elbow injuries can be classifi ed as acute or chronic. Acute injuries are more common Sports with compressive loads across in contact and collision sports (American football, the elbow rugby, ice hockey, and martial arts) or in any sport at risk of high energy falls (skiing, snowboard- Repetitive compressive loads across the elbow such ing, gymnastics, and equestrian). There may be as seen in weight-lifting, boxing, and gymnastics direct (impact directly onto the elbow) or indirect are another key risk factor for the development of (fall on an outstretched hand or torques across Preventing elbow injuries 161

Figure 10.6. Fall on an outstretched hand (FOOSH) is a common cause of elbow injury and dislocation the elbow. Most acute injuries are hazards of the supracondylar fracture is essential to avoid long- sport and therefore difﬁ cult to prevent. Educating term complications of malalignment or arthritis. athletes on how to fall and the use of protective Admittedly, this does not prevent the initial injury equipment like elbow pads in certain sports may but early recognition and treatment can prevent provide some prevention effect. later problems and disability.

FOOSH: fall on an outstretched hand Direct impact injuries

The classic description is a fall on an outstretched Direct impact onto the elbow by an object, impact hand (FOOSH) (Figure 10.6). When the forces are onto the court surface, or collision into a barrier excessive, the elbow is hyper-extended leading wall can lead to elbow injuries including bone fi rst to rupture of the collateral ligaments (medial bruises, ligament strains, muscle contusions, and before lateral) and anterior capsule. If the force skin abrasions. The ulnar nerve is relatively sub- continues, the elbow will dislocate. In some cases, cutaneous on the posterior medial aspect of the bony avulsions of ligaments or apophyses will elbow. Direct impact can lead to a temporary neu- occur instead of pure ligamentous injury. In severe ropraxia or chronic ulnar neuritis. Direct impact injuries, neurovascular structures will be injured onto the olecranon can lead to an infl amed or with severe displacement. Urgent reduction is blood-fi lled olecranon bursa. Prevention of these essential. In athletes who fall on extended elbow direct impact injuries can usually be accomplished with the hand in full supination, there is a risk of through protective padding. Unfortunately, many an isolated injury to the posterolateral corner of acute injuries are simply accidents which occur the elbow. In this case, the lateral collateral liga- during the usual performance of a high risk sport. ment and annular ligament at the radial neck are One potential exception is the risk of elbow dis- injured and lead to posterior subluxation or insta- location in the sport of judo. In judo, a competi- bility of the radial head. tor is allowed to place his opponent’s elbow in an In children who fall on an outstretched arm, the elbow lock, a position of hyperextension. Indeed, weak link is the growth plate. Injuries that appear if the athlete on the receiving end of this maneu- as elbow dislocations frequently have associated ver does not “tap-out” to concede defeat contin- epiphyseal or apophyseal injuries. It is strongly rec- ued force may lead to an elbow dislocation. ommended to obtain bilateral radiographs in the skeletally immature for comparison. The appear- Overuse injuries ance and position of each growth center should be symmetric to the opposite side. Anatomic reduc- While traumatic injuries can occur across sports, tion of any displaced intra-articular fracture or a the most elbow problems in athletes are secondary 162 Chapter 10 to chronic repetitive stresses. Fortunately, it is this to load the articular surface directly. In each case overuse that gives us our best target to prevent the ligaments and bones feel the direct force of the elbow injuries. Repetitive varus loading as seen in loading, however, the muscles that cross the joint the lead hand in golf and in the backhand dur- serve as dynamic stabilizers that are at risk of injury ing tennis leads to strain of the lateral collateral with repetitive overuse. ligament as well as the wrist extensor muscles. To resist varus loading, the lateral muscles fi re to Repetitive valgus stress seen in throwing and rac- assist in stabilizing the joint. Unfortunately due to quet sports leads to an increased strain of the the relative proximity to the joint surface they are medial collateral ligament, overuse of the fl exor at a mechanical disadvantage to overcome these muscles, and compression of the radiocapitel- repetitive loads. The classic example of this occurs lar articulation (Figure 10.7). Repetitive extension with the tennis backhand. Energy is transferred at loads seen in the follow-through phase of throwers ball impact through the racquet to the wrist exten- or when weightlifters lock their elbow in full extensors which insert on the lateral aspect of the elbow. sion can lead to impingement of the olecranon Chronic repetitive overuse with inadequate oppor- posteriorly, traction of the triceps muscle, and ten- tunity to recover leads to tendon failure or tendin- sion the capsule anteriorly. Repetitive compressive opathy of the wrist extensors, most commonly the loads seen in gymnastics and weight-lifting serve extensor carpi radialis brevis. Indeed a similar phe- nomenon is seen on the medial aspect of the elbow in golfers (Figure 10.8). As ball impact occurs or a divot is taken, forces are transferred up the shaft to the wrist fl exors as the insert on the medial aspect of the elbow. Golfer’s elbow is a tendinopathy on the medial aspect of the elbow secondary to overuse or injury the fl exor muscle insertions onto the medial epicondyle. It is possible that the strong supination of the lead hand/pronation of the trailing hand that occurs during the golf swing could

Figure 10.7. Valgus-extension overload is the most common mechanism of overuse injuries about the throwing elbow. It is made up of medial tension, lateral compression and posterior olecranon impingement. Figure 10.8. Golfer’s elbow is an overload of the medial Reproduced with permission @ Mark R. Hutchinson, UIC structures of the elbow which can be caused by acutely Sports Medicine taking a deep divot Preventing elbow injuries 163 contribute to this problem; however, this would to resist the large extension moment. The extension not explain the increased incidence in the amateur moment is also resisted by the bony architecture population compared to the professional ranks. posteriorly as the olecronon falls into the olecranon The more likely mechanism of injury is that the fossa posteriorly. This repetitive valgus loading and injury occurs when the golfer hits down on the extension moment can lead to specifi c group over- ball too forcefully and takes too large a divot. This use injuries and, therefore, this pathomechanic has would lead to acute loads of the fl exor muscles been coined valgus-extension overload. The valgus of the trailing hand at impact. Indeed this occurs component can lead to ulnar collateral instability, much more frequently in amateur golfers than pro- avulsions of medial epicondyle, medial epicondyle fessional golfers who have honed their swing. epiphysitis, secondary ulnar nerve neuropraxia. In addition the valgus loads apply compressive loads Injuries in throwing sports to the radio-capitellar articulation which can lead to radial head fractures, radial head hypertrophy, oste- Perhaps the greatest focus of study on injury mecha- ochondral lesions, degeneration of the capitellum, nisms about the elbow has occurred in throwing or osteochondritis dissecans. The extension compo- sports. As the ball or javelin is delivered, the elbow nent leads to posterior olecranon impingement. In goes through a sequence of muscle activity, loading, association with valgus instability, this extension and mobility that stresses different aspects of the component leads to specifi c spurs on the posterior joint through the range of motion. In the early cock- medial aspect of the olecranon that engage during ing phase, the elbow is usually in slight to moderate the throwing motion and can lead to pain or create fl exion and is relatively at a low stressful position loose bodies. This valgus extension overload mecha- as the arm is being positioned to begin transferring nism is exactly the same during the overhead service loads up the kinetic chain with the goal of ulti- in racquet sports. mately delivering the projectile from the hand. In Another common mechanism of chronic elbow late cocking and early acceleration the medial col- injury is the repetitive compressive loading as seen lateral ligament and radiocapitellar articulation are in sports such as gymnastics, boxing, and weight- loaded with valgus stress that continues to increase lifting. The anatomic structures at risk are the as acceleration occurs (Figure 10.9). Throwers usu- same as those with throwing athletes; however, the ally pronate their arms to some degree in this phase compressive loads are greater. This places the artic- to reduce the intense valgus loads. As the projectile ular surface at a relatively greater risk of overuse is delivered, the elbow comes into full extension and failure compared to throwers with similar number the perarticular muscles (especially elbow fl exors) fi re of loads events. This may explain why gymnasts

Figure 10.9. The normal throwing sequence consists of wind-up, cocking, acceleration, and follow-thru phases. With approval @ Mark R. Hutchinson, UIC Sports Medicine 164 Chapter 10 who suffer osteochondritis dissecans have a miser- throws on too little rest is directly related to an able prognosis regarding return to sport compared increased injury incidence. Likewise for the mature to their young baseball counterparts who seem to thrower, overuse elbow injuries have been related have a better prognosis. to the total number of pitches and amount of rest between outings. For the mature athlete, core strength and a coor- Identifying risks in the training and dinated kinetic chain have a central role in injury competition program prevention. Coaches and trainers should carefully evaluate the throwing mechanic of their athletes early in the training season to assure that there As we have seen, multiple factors contribute to the are no defi cits in the kinetic chain that might pre- incidence and prevalence of elbow injuries in ath- dict future injury. During competition, the kinetic letes. The relationship of training, practice, or com- chain may also play a key role in the risk of elbow petition to injury incidence has been well studied injury. As the athlete fatigues later in competition, regarding injuries in general but less well evaluated he is more likely to overuse single components of for elbows in particular. The key issues for elbow the kinetic chain leading to a failure of the coordi- injuries are the number of repetitions or exposure nated sequence of movement and placing any link to traumatic events in training versus competitive at risk of injury. Based on this knowledge, coaches situations. In contact and collisions sports, the ath- should be astute observers of athletic performance lete is at greater risk of acute trauma during compe- and biomechanics during competition. The ath- tition where their opponent is trying to overwhelm lete should be removed from play when proximal their strength or position. In practice situations, links of the kinetic chain reveal weakness, poor players more frequently are less “all out” as com- coordination, or failure because the elbow may be pared to a competition. An exception to this rule is the next link to fail. spring football in American rules football in which teams play competitively amongst their own team vying for positions on the next years teams. Injury rates are greater at this time than the regular sea- Preventive measures son. For gymnasts, they are at risk of traumatic injuries at any time they are at competition height The foundation of a targeted prevention plan to on apparatus regardless practice or competition. reduce elbow injuries should be based on available Training versus competition seems to have a science and our historical knowledge regarding major effect on overuse injuries. Overuse injuries incidence and mechanism. The ideal of eliminat- are always more common when an athlete begins ing all injuries is not reasonable as athletic par- to train intensely after an extended period of rest ticipation carries some inherent risk. Nonetheless, or when they are asked to signifi cantly ramp up minimizing risk and preventing the progression of their training immediately prior to a major com- a minor defi cit or problem to a more signifi cant petition or event. This is true for the elbow as it injury is clearly our best option. A valid preven- is for most body parts. Prevention usually targets tion plan should target the injury patterns that are a gradual increase in stresses and intensity rather most common, most potentially disabling, and in than these acute changes in training patterns to which intervention can be the most effective. avoid the risk of overuse injuries.

Skeletal maturity and training Targeting acute injuries

For the skeletally immature thrower, the injury risk For acute and traumatic injuries of the elbow, pre- appears to be less related to training or competition vention should target minimizing risk exposures compared to the actual number of full speed tosses and energy level when such an exposure would they perform in a given time period. Too many not affect the routine and legal performance of Preventing elbow injuries 165

Table 10.3 Injury prevention matrix for elbow injuries: potential measures to prevent injuries.

Precrash Crash Postcrash

Athlete Hand dominance Falling techniques Comparative radiographs in children to Throwing technique avoid missing complex injuries Backhand technique in tennis Regain motion ASAP to avoid Core strength and stability contractures Optimal shoulder function Pitch counts Rules Restrictions of repetitions in underage throwers Regulations versus at risk techniques in martial arts Material String tension in racquet sports Elbow pads in collision sports Therapeutic taping to avoid recurrent Racquet rigidity hyperextension Length of racquets Pads to avoid recurrent bursitis Decrease weight of projectiles Environment Rainy weather increases ball weight Padded surfaces absorb fall First aid readily available energy Only qualiﬁ ed professional to perform reduction of dislocation

the sport. This may be accomplished via rigid rule in which a fall could be catastrophic. Equipment enforcement, more severe penalties for violations, and apparatus should be checked for proper func- or rules changes. An example that has been effec- tion before competition begins. If competition tive was limiting the height of cheerleader tow- apparatus is unstable or set at the wrong height, ers which, in turn, reduced the potential energy it may predispose the athlete to a fall. There is and risk of injury from falls (Boden et al., 2003). good literature to support that the use of elbow Examples that could be effective include rules pads in rollerbladers reduces their risk of elbow changes, the imposition of stiffer penalties or the injuries especially of contusions and abrasions rigid enforcement of existing rules that prevents (Schieber et al., 1996; Jerosch et al., 1998; Sheiker a wrestler from lifting his opponent off the matt & Casell, 1999). Elbow injuries in rollerbladers are or tossing his opponent through the air. In judo, most strongly correlated with their willingness banning the ability of a competitor to hyperex- to perform advanced tricks and maneuvers. The tend the elbow (or dislocate it) until his opponent use of elbow protection in sports at risk of direct taps out (gives up) would likely reduce the risk of contusion such as hockey, lacrosse, or racquet- elbow injuries in that sport. ball may reduce the risk of these contact injuries. In addition better designs and fi tting with Targeting the environment improved shock absorption may assist to a diffuse the load of the more signifi cant direct injuries Targeting issues of athlete fatigue as well as ensur- (Table 10.3). ing safe equipment and environment would also reduce the risk of elbow problems. Athletes Targeting overuse should be instructed to rest when fatigued. This is especially true when their partner is dependent While avoiding a single catastrophic injury, par- on their elbow’s strength and function (pairs fi g- ticularly for the individual athlete, is important, ure skating, cheerleading) or when they are partic- the most effective aim for elbow injury prevention ipating in a high energy sport such as gymnastics should target the most common injuries; that is, 166 Chapter 10 overuse injuries. The foundational knowledge of Table 10.4 Interval throwing program: baseball. All injury risk, risk factors, and mechanisms should throws should be on an arc with a crow hop. Warm-up throws should be 10–20 tosses at 30 ft. Perform each serve as our guide to developing an injury pre- step 2–3 times before progressing. If pain occurs go to vention plan for the elbow that can be applied to previously level. Distances should be shortened for Little all sports but also one that can be individualized Leaguers. to create a sport-specifi c plan. Athlete’s at risk of Step Throwing program elbow injuries due to a history of previous elbow injuries or due to their participation in at risk Step 1 & 2: 45-ft Phase sports golf, baseball, softball, javelin, tennis, and 1. Warm-up, 25 tosses, 5-min rest, repeat wrestling should be more thoroughly evaluated on 2. Warm-up, 25 tosses, 5-min rest, repeat twice preparticipation physical examinations. The pres- Step 3 & 4: 60-ft Phase 3. Warm-up, 25 tosses, 5-min rest, repeat ence of elbow stiffness or pain should be addressed 4. Warm-up, 25 tosses, 5-min rest, repeat twice with appropriate therapy prior to release for unre- Step 5 & 6: 90-ft Phase stricted training. Extension loss of greater than 5. Warm-up, 25 tosses, 5-min rest, repeat 15º at the elbow or an abnormal carrying angle 6. Warm-up, 25 tosses, 5-min rest, repeat twice secondary to development or previous injury will Step 7 & 8: 120-ft Phase likely lead to abnormal mechanics and future over- 7. Warm-up, 25 tosses, 5-min rest, repeat use injury. For all overhead and upper extremity 8. Warm-up, 25 tosses, 5-min rest, repeat twice dominant athletes, the screening program should Step 9 & 10: 150-ft Phase also include a thorough assessment of shoulder 9. Warm-up, 25 tosses, 5-min rest, repeat function and motion. Posterior capsular tightness 10. Warm-up, 25 tosses, 5-min rest, repeat twice evidenced by a loss of internal rotation has been Step 11 & 12: 180-ft Phase directly associated with both shoulder and elbow 11. Warm-up, 25 tosses, 5-min rest, repeat complaints. Fortunately in a large majority of 12. Warm-up, 25 tosses, 5-min rest, repeat twice cases, the shoulder tightness responds to a focused Step 13 & 14: progression to pitching: fl at ground stage program of capsular stretches including cross-over 13. Warm-up, 60-ft/15 tosses, 90-ft/10 tosses, stretches, internal rotation stretches, and “sleeper” 120-ft/10 tosses, 60-ft/20 tosses using stretches. The latter are performed as the ath- pitching mechanics from fl at ground lete lays on his side trapping the effected scapula 14. Step 13, 10-min rest, repeat between his body and the bed followed by inter- Step 15: pitching: mound stage 15. Progression to pitching from mound nal rotation stretches in various positions.

Targeting training or of the young cheerleader/gymnast attempting When athletes return to play after a signiﬁ cant a stunt beyond her skill level and risking a cata- period of rest or injury, their return should be slow strophic fall on her outstretched hand. and progressive. Acute and intense increases in the training regimen at the beginning of the season, Targeting the athlete at risk prior to major competitions, or during injury recovery have been associated with recurrence or over- The at-risk athlete should also be screened at the use injury. A slow progressive recovery program has time of his preparticipation examination for coor- the best opportunity for successful return to play dinated movement, strength and symmetry along without recurrence (Tables 10.4, 10.5 and 10.6). the entire kinetic chain. Scapular dyskinesia can be In addition to conditioning, coaches should also assessed by inspecting the athlete from posterior assure that athletes also have a gradual progression and asking them to protract, retract, and elevate in skills from fundamental to more complex. This their shoulders with their arms at the sides, hands plan would avoid the risk of the immature baseball on their hips, and with their arms abducted 90º player throwing a curveball with poor mechanics (Box 9.1). Any side-to-side asymmetry should be Preventing elbow injuries 167

Table 10.5 Interval rehabilitation program: tennis Table 10.6 Interval rehabilitation program: golf (Reinhold et al., 2005). (Reinhold et al., 2005).

Week # Monday Wednesday Friday Week # Monday Wednesday Friday

Week 1 12FH 15 FH 15FH Week 1 10 putts 15 putts 20 putts 8BH 8BH 10BH 10 chips 15 chips 20 chips 10-min rest 10-min rest 10-min rest 5-min rest 5-min rest 5-min rest 13FH 15FH 15FH 15 chips 25 chips 20 putts/20 chips 7BH 7BH 10BH Week 2 20 chips 20 chips 15 short irons Week 2 25FH 30FH 30FH 10 short irons 15 short irons 20 med irons 15BH 20BH 25BH 5-min rest 10-min rest 10-min rest 10-min rest 10-min rest 10-min rest 10 short irons 15 short irons 20 short irons 25FH 30FH 30FH 15 med irons 15 chips 15 chips 15BH 20BH 25BH 5 iron off tee putting ad lib putting ad lib 15 med irons 15 medium irons Week 3 30FH, 25BH 30FH, 25BH 30FH, 30BH 10 Serves 15 Serves 15 Serves Week 3 15 short irons 15 short irons 15 short irons 10-min rest 10-min rest 10-min rest 20 med irons 15 med irons 15 med irons 30FH, 25BH 30FH, 25BH 30FH, 25BH 10-min rest 10 long irons 10 long irons 10 Serves 15 Serves 15 Serves 15 short irons 10-min rest 10-min rest 15 med irons 10 short irons 10 short irons Week 4 30FH, 30BH 30FH, 30BH 30FH, 30BH 5 long irons 10 med irons 10 med irons 10 Serves 10 Serves 10 Serves 10-min rest 5 long irons 10 long irons 10-min rest 10-min rest 10-min rest 20 chips 5 woods 10 woods Play 3 games Play set Play 1.5 sets 10FH, 10BH 10FH, 10BH 10FH, 10BH Week 4 15 short irons Warm-up Warm up 5 Serves 5 Serves 5 Serves 15 med irons Play 9 holes Play 9 holes 10 long irons *FH forehand shots; BH backhand shots. 10 drives 15-min rest Repeat Week 5 Play 9 holes Play 9 holes Play 18 holes addressed with focused rehabilitation. Evaluation of core strength and coordination is also important. During the preseason screening evaluation, all overhead athletes should be asked to perform a throwing, weight-bearing and weight-lifting sports single-legged squat on both a stable and an unsta- need to be educated to offer complaints of elbow ble surface (foam pad, balance board, mini-tramp). pain when present. Delayed diagnosis can lead to The observer should look for poor balance in the poorer prognosis. For example, young gymnasts upper body with arm swaying or inability to main- should never participate in the presence of undiag- tain single leg stance, hyperﬂ exion of the lumbar nosed pain for fear of making the pathology worse. spine instead of a true knee squat, and gluteal Mild degrees of osteochondritis dissecans can be weakness evidenced by knee internal rotation or treated with rest and have a signiﬁ cantly better dropping the contralateral pelvis (Figure 5.7). Any prognosis than advanced degrees of osteochondri- abnormalities discovered should be addressed with tis dissecans with loose bodies. Indeed gymnasts focused training and has been shown to reduce the compared to all sports have the worst prognosis incidence of elbow problems in athletes (Kibler & regarding return to sport when the osteochondritis Sciascia, 2004). dissecans is severe. Another example is the mature athlete with a prodrome of bicipital tendonitis or Targeting early recognition medial collateral ligament pain. Continued participation and loading can lead to complete rupture, Educational programs may also target the reduc- while early treatment and rest may avoid the need tion of injury incidence and severity. Athletes in of surgical intervention completely. 168 Chapter 10

Focused, sport-specifi c injury prevention inter- aspect of the elbow. Athletes with a history of or vention plans should target the three most studied at risk of tennis elbow should consider switching sports regarding overuse elbow injuries; golf, ten- to a two-fi sted backhand to diminish the loads. nis, and baseball. These plans can easily be trans- The next most common injury pattern in tennis lated to other sports using baseball as a model for players are related to the repetitive valgus-exten- throwing sports, tennis as a model for racquet sion overload that occurs with overheads and sports, and golf as model for stick sports. the tennis serve. This pattern mimics that seen in throwing athletes. Strains or rupture of the medial collateral ligament, compression injuries of the Targeting golf capitellum, and posterior impingement lesions have been identifi ed just like those seen in base- Golf has a surprisingly high rate of elbow inju- ball. Indeed the severity may be magnifi ed by the ries, particularly for the amateur athlete (see increased fulcrum provided by the additional rac- Table 10.1). The length of the golf club increases quet extension to the site of impact. Prevention the force moment that magnifi es the energy that plans include athlete education to optimize early crosses the elbow joint. As noted earlier, this identifi cation and initiation of treatment; prepar- mechanism has been associated with the devel- ticipation screening identifying risks in both the opment of golfer’s elbow or a tendinopathy on elbow and the shoulder, conditioning programs the medial aspect of the elbow. Prevention cent- that focus on every facet of the kinetic chain (Box ers on an increased awareness of the risk as well as 10.1). To avoid overuse elbow problems in the improving the mechanics of the golf swing includ- skeletally immature, an evaluation of the number ing impact. Avoid taking large divots. Optimize of serves, overheads, and backhands performed swing mechanics. Equipment modifi cations may in a given session or week may be of benefi t. This also be helpful with more fl exible shafts to absorb has clearly been effective in reducing the risk of shock, appropriate grips for hand size, and broader injury in skeletally immature throwers (Lyman head designs with peripheral weighting to maxi- et al., 2002; Dugas, 2006; Olsen et al., 2006). mize the sweet spot. Indeed, there is a good support to this plan in skeletally immature throwers in little league baseball. Targeting tennis Targeting baseball and overhead A majority of elbow injuries related to tennis are throwers related to either repetitive varus forces with active wrist extension during the backhand or repeti- To begin targeting the throwing athlete, most ath- tive valgus extension overload during the serve. letes are placed on a routine program of rotator cuff Reduction of the risk of tennis elbow begins with strengthening, scapular stabilization exercises, core the proper equipment. The grip should not be too strengthening and posterior capsular stretches. Those small placing the extensors on tension and at risk with defi cits are asked to participate in a supervised of injury. For beginners and intermediate level program until the defi cits are corrected (Box 10.2). players, high tension racquets are unnecessary The second key intervention for overhead throw- for success and may be avoided while skills are ers is educating the athlete regarding overuse and advancing. Oversized heads and other equipment monitoring the number of throws they perform designs that help to absorb the shock of impact and the amount of rest between each outing. This or assure optimal contact may also be helpful. is especially true for the skeletally immature ath- Counterforce bracing has also been popular to lete. Controlled number of pitch counts per week decrease the focal loads on the lateral aspect of the and season with prescribed numbers of days or rest elbow. Many athletes have switched to a two-fi sted between outings has been directly correlated with backhand because it allows them increased power, reduced risk of elbow injuries in both the immature more control, and reduced forces over the lateral and the mature throwers (Table 10.7) (Lyman et al., Preventing elbow injuries 169

Box 10.1. Injury prevention protocol for tennis

1. Low-to-high pull with resistance against weight or tubing 4. 90–90 external rotation with resistance against weight or – Begin reaching low across body outside of contralateral foot tubing – Explosive lift the arm into full abduction and external rotation – Begin with the arm at 90º of abduction and neutral position – Slowly return to the ﬁ rst position – Externally rotate against resistance – Repeat 1–3 sets, 15–20 repetitions – 1–3 sets, 15–20 repetitions

2. Straight arm rowing with resistance against weight or tubing 5. Wrist extension (strengthening) with resistance against weight – Begin with arms straight in front with in line tension or tubing – Pull arms into extension while squeezing shoulder blades – While seated and forearms resting comfortably on thigh together as if rowing a boat – Extend wrists from a ﬂ exed, palm down position to full – Repeat 1–3 sets, 15 repetitions extension – 1–3 sets, 15–20 repetitions

3. Standing external rotation with resistance against weight or tubing – With the arm at the side & 0º of abduction & neutral rotation – Externally rotate against resistance – 1–3 sets, 15–20 repetitions 6. Wrist ﬂ exion (strengthening) with resistance against weight or tubing – While seated and forearms resting comfortably on thigh

(Continued) 170 Chapter 10

Box 10.1 (Continued)

– Flex wrists from a extended, palm up position to – Twist forearm palm down against resistance full ﬂ exion – 1–3 sets, 15–20 repetitions – 1–3 sets, 15–20 repetitions 8. Forearm supination with resistance against weight or tubing 7. Forearm pronation with resistance against weight or – While seated and forearms comfortably resting on thigh tubing – Wrap resistance tubing around hand so that it exits on the – While seated and forearms comfortably resting on thigh thumb side of the hand and secure the free end – Wrap resistance tubing around hand so that it exits on the – Hand should be positioned palm up until resistance is felt thumb side of the hand and secure the free end in tubing – Hand should be positioned palm up until resistance is felt – Twist forearm palm down against resistance in tubing – 1–3 sets, 15–20 repetitions.

Source: Shoulder and elbow injury prevention protocol from United States Tennis Association (www.playerdevelopment. usta.com).

Box 10.2 The thrower’s 10 exercise prevention program

1. Diagonal pattern D2 extension/ﬂ exion – Repeat above but begin with arm in full external rotation – Stand, using resistance tubing begin with arm in full and pull on resistance at both 0º and 90º of abduction into abduction and external rotation and pull tubing down and full internal rotation across the body to the opposite side of the leg – Using resistance tubing begin with arm crossed over body bear opposite hip and pull tubing into full abduction and external rotation position

2. External/internal rotation at 0º and 90º of abduction – Stand, using resistance tubing begin with arm in fully internally rotated position, ﬁ rst with arm at 0 abduction then with arm in 90º of abduction – Pull on resistance while rotating into full external rotation

(Continued) Preventing elbow injuries 171

Box 10.2 (Continued)

5. Press-ups – Seated on a chair or table, place both hands ﬁ rmly with palms down – Slowly push downward on both hands to elevate your body – Hold for 2 s, lower slowly

6. Prone horizontal abduction – Lie on table face down with arm hanging to ﬂ oor, hold barbell weight or against tubing resistance, extend the arm 3. Shoulder abduction to 90º laterally, parallel with the ﬂ oor – Stand holding a 5 pound weight or against resistance – Hold 2 s, lower slowly tubing begin with arm at side then abduct the shoulder to – Repeat both in neutral and full external rotated positions 90º with elbow in full extension

4. Scaption, internal rotation – Stand with arm at side and elbow straight and thumb up 7. Prone rowing – Raise arm to shoulder level at 30º angle in front of body (in Lie on table face down with arm hanging to ﬂ oor and holding plane of scapula) barbell weight, pull backwards, ﬂ exing the elbow as if rowing – Hold for 2 s, lower slowly – Bring the dumbbell up as high as possible – Hold for 2 s and slowly lower

(Continued) 172 Chapter 10

Box 10.2 (Continued)

8. Push-ups – Straighten elbow over head against resistance or barbell Place hands no more than shoulder width apart. Push up as weight. Hold 2 s and slowly lower high as possible rolling shoulders forward after elbow lock straight 10. Wrist extension/fl exion, supination/pronation – Supporting the forearm on a table with the palm faced 9. Elbow fl exion/extension down, extend the wrist against weight or tubing resistance – With arm against side and in full supination, lift barbell – With the palm faced up, fl ex the wrist against weight or weight or against resistance tubing, hold 2 s and lower tubing resistance slowly – With the wrist in neutral position use a hammer, off- – Lift arm overhead and support elbow. centered weight, or tubing to resist placing the arm in to a palms-up position – With the wrist in neutral position use a hammer, off- centered weight, or tubing to resist placing the arm in to a palms-down position

Source: From James Andrews, American Sports Medicine Institute. Video illustrations available at http://www.asmi.org/sportsmed/ throwing/thrower10.html.

2002; Dugas, 2006; Olsen et al., 2006). These guide- the full speed pitch count should be applied to the lines are based on performance pitch counts and not pitch count guidelines. Prevention guidelines for the tosses from other positions; however, the clinician skeletally immature also include recommendations should ask the athlete if they participate in more regarding the appropriate age to add certain types than one league, pitch at full speed between games, of pitches (Table 10.8). It should be emphasized to or perform showcase events. In any of those cases, the young thrower that a proper throwing mechanic Preventing elbow injuries 173

Table 10.7 Pitch count guidelines in Youth Baseball injuries. For children, reducing exposure by impos- from USA Baseball and the American Sports Medicine ing pitch counts or throwing limits can reduce the Institute. incidence of injury and early identiﬁ cation and Age group Throwing program rest can prevent them from becoming more severe. A simple rule for coaches of skeletally immature 9–10 year olds athletes is that they should not play through pain. 50 pitches per game 75 pitches per week The return to play for all injured elbows should be 1000 pitches per season gradual and progressive. In thrower’s this is done 2000 pitches per year via a throwing protocol which begins with light 11–12 year olds tosses and progresses in distance and speed. If the 75 pitches per game athlete returns too quickly he risks reinjuring his 100 pitches per week 1000 pitches per season elbow. A universal program to reduce the risk of 3000 pitches per year elbow injuries must look beyond the elbow joint 13–14 year olds itself and include training and coordination of the 75 pitches per game entire kinetic chain. Preseason screening programs 125 pitches per week to identify core weaknesses including such things 1000 pitches per season 3000 pitches per year as single leg squats on unstable surfaces and evaluation of scapular dynamics can help to identify the athlete at risk. Table 10.8 Guidelines for the institution of pitch types in Little Leaguers from USA Baseball and the American Sports Medicine Institute.

Pitch type Age (years) References Fastball 8–10 Change-up 10–13 Boden, B.P., Tachetti, R., Mueller, F.O. (2003) Curveball 14–16 Catastrophic cheerleading injuries. American Journal of Knuckle ball 15–18 Slider 16–18 Sports Medicine 31, 881–888. Fork ball 16–18 Dugas, J.R. (2006) Prevention of overuse in the Screwball 17–19 adolescent thrower. Sports Medicine Update, American Orthopaedic Society for Sports Medicine 1, 4–7. Jerosch, J., Heidjann, J., Thorwesten, L., Lepsein, U. (1998) Injury pattern and acceptance of passive and active injury prophylaxis for inline skating. Knee and not some new tricky pitch will most improve Surgery Sports Traumatology and Arthroscopy 6, 44–49. their performance and outcomes. Kibler, W.B., Sciascia, A. (2004) Kinetic chain contributions to elbow function and dysfunction in sports. Clinics in Sports Medicine 23, 542–552. Take-home message Lyman, S., Fleisig, G.S., Andrews, J.R., Osinski, E.D. (2002) Effect of pitch type, pitch count and pitching The elbow serves an integral role in many sports mechanics on risk of elbow and shoulder pain in making the importance of maintaining opti- youth pitchers. American Journal of Sports Medicine 30, mal function and avoiding injuries is an impor- 463–468. tant goal for athletes. Not all elbow injuries, Olsen, S.J., Fleisig, G.S., Dun, S., Loftice, J., Andrews, J.R. particularly many of the traumatic ones, are avoid- (2006) Risk factors for shoulder and elbow injuries in able. Nonetheless, the incidence of those may be adolescent pitchers. American Journal of Sports Medicine 34, 905–912. reduced by following the rules of play, optimiz- Reinhold, M.M., Wilk, K.E., Reed, J., Crenshaw, K., ing equipment, and avoiding fatigue for at risk Andrews, J.R. (2005) Interval sports programs: athletes. The best target for injury prevention of guidelines for baseball, tennis, and golf. Journal of elbow injuries should target the repetitive overuse Orthopaedic and Sports Physical Therapy 32, 293–298. 174 Chapter 10

Schieber, R.A., Branche-Dorsey, C.M., Ryan, G.W., Field, L.D., Altchek, D.W. (1995) Elbow injuries. Clinics in Rutherford Jr., G.W., Stevens, J.A., O’Neil, J. (1996) Sports Medicine 14, 59–78. Risk factors for injuries from in line skating and Fleisig, G.S., Barrentine, S.W., Escamilla, R.F., effectiveness of safety gear. New England Journal of Andrews, J.R. (1996) Biomechanics of overhand Medicine 28, 1680–1682. throwing with implications for injuries. Sports Medicine Sheiker, S., Casell, E. (1999) Preventing in-line skating 21, 421–437. injuries: how effective are the countermeasures? Sports Hutchinson, M.R., Laprade, R.F., Burnett, Q.A., Medicine 28, 325–335. Moss, R., Terpstra, J. (1995) The incidence and prevalence of injuries at the United States Tennis Association’s national boys championships. Medicine and Science in Sports and Exercise 27, 826–830. Further reading Hutchinson, M.R., Wynn, S. (2004) Biomechanics and development of the elbow in the young throwing athlete. Clinics in Sports Medicine 23, 531–544. Andrews, J.R., Zarins, B., Wilk, K. (1998) Injuries in McCarroll, J.R. (2001) Overuse injuries of the upper Baseball. Lippincott-Raven Publishers, Philadelphia, PA. extremity in golf. Clinics in Sports Medicine 20, Cain, E.L., Dugas, J.R., Wolf, R.S., Andrews, J.R. (2003) 469–479. Elbow injuries in athletes: a current concepts review. NCAA (2006) NCAA Injury Surveillance System. National American Journal of Sports Medicine 31, 621–635. Collegiate Athletic Association, Indianapolis, IN. Caine, D.J., Nassar, L. (2005) Gymnastics injuries. Stockard, A.R. (2001) Elbow injuries in golf. Journal of the Medicine and Science in Sports and Exercise 48, 18–58. American Osteopathic Association 101, 509–516. Chapter 11 Preventing injuries to the head and cervical spine Paul McCrory1, Michael Turner2 and Andrew McIntosh3

1Centre for Health, Exercise and Sports Medicine, University of Melbourne Parkville, Australia 2Chief Medical Adviser, British Horseracing Authority and Lawn Tennis Association; formerly CMA to British Olympic Association and Snowsport, UK 3School of Risk and Safety Sciences, The University of New South Wales, Sydney Australia

Epidemiology of head and cervical Pathophysiology of head and spine injuries in sports neck injury

Sports involving collision, body contact, projec- Non-penetrating brain injury (or closed head tiles, and/or high speeds are associated with a risk injury) may be divided into primary and sec- of head and neck injury. The range of potential ondary injuries. Primary injury is the result of head and neck injuries—from facial lacerations to mechanical forces producing tissue deformation intracranial hemorrhage, from mild neck strains to at the moment of injury. These deformations may spinal cord lesions makes this area of injury man- result in either functional disturbance or structural agement particularly diffi cult. disruption of cell membranes. The injury may also Fortunately, most sports-related head and neck set in train a complex cascade of biochemical, injuries are mild. However, severe and sometimes immunological, or coagulopathic changes that fatal injuries do occur which makes the need to may cause further damage. prevention of such injuries critical. It is worth Secondary damage occurs as a complication of also observing that head and neck injuries do not primary injury and includes hypoxic and ischemic always occur on the sports fi eld; a child spectator damage, brain swelling, hydrocephalus, and infec- died in 2002 after being struck in the head by an tion. Sports concussion by defi nition has no ice hockey puck in the United States and in 2001, macroscopic neuropathological damage and it is a track marshal was killed during a Formula 1 speculated that the critical physiological change championship race. occurs at the cell membrane level. There has also These tragic examples indicate that injury pre- been recent evidence to suggest a signifi cant genetic vention must be multi-faceted, addressing, in basis to head injury outcomes (Aubry et al., 2002; these cases, the “built” environment, training, and McCrory et al., 2005). supervision. Concussion and mild traumatic brain injury Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing Sports concussion has been defi ned as a complex ISBN: 9781405162449 pathophysiological process affecting the brain,

175 176 Chapter 11 induced by traumatic biomechanical forces (Aubry Table 11.1 Risk of concussion in elite sports. et al., 2002; McCrory et al., 2005). Several com- Sport Incidence per 1000 h of exposure1 mon features that incorporate clinical, pathological, and biomechanical injury constructs that may Horse racing 25.0 Kickboxing 4.8 be utilized in defi ning the nature of a concussive Australian football 4.2 head injury include: Professional boxing 3.9 1. Concussion may be caused either by a direct Rugby union football 3.9 blow to the head, face, neck, or elsewhere on the Cricket 2.0 body with an “impulsive” force transmitted to the Ice hockey 1.5 Football/Soccer 0.4 head. American football 0.2 2. Concussion typically results in the rapid Skiing/snowboarding 0.05 onset of short-lived impairment of neurological Baseball 0.0043 function that resolves spontaneously. The numbers reported are average estimates based on the 3. Concussion may result in neuropathological studies available. changes, but the acute clinical symptoms largely 1Incidence is reported for adult, competitive athletes as the refl ect a functional disturbance rather than number of injuries per 1000 h of competition. structural injury. 4. Concussion results in a graded set of clinical Although this is suggested by retrospective stud- syndromes that may or may not involve loss of ies and theoretical modeling, no prospective study consciousness. Resolution of the clinical and of rugby spinal cord injury has been performed cognitive symptoms typically follows a sequential before and after the introduction of rule changes course. to reduce scrum-related injury. Studies of “spinal” 5. Concussion is typically associated with grossly injury in rugby union demonstrate that the scrum normal structural neuroimaging studies. and tackling constitute high risk injury mecha- In Table 11.1, the incidence of concussion is nisms for non-catastrophic neck injury. However, presented using common exposure risk. It can be the number of spinal cord injuries is too low in seen that sports where high velocity impacts (e.g., the study to provide a meaningful statement as to equestrian sports) occur, the risk of head injury is spinal cord injury risk due to these mechanisms the greatest. (Fuller et al., 2007). Interestingly there is some data to suggest that the spinal cord injury rate differs signifi cantly with age, with schoolboy rugby Catastrophic head and spinal cord players having spinal cord injury rates approxi- injury mately one-third that of adult players. Catastrophic head and spinal cord injury occur in With regard to fatal head injury, the only com- virtually all sports. In total 497 persons have died parative data between sports and/or recreational while playing American football in the United activities was performed in the United Kingdom a States since 1945; of these 69% died from fatal brain number of years ago (Lyens et al., 1984). The fi nd- injuries and 16% from spinal cord injury (Levy et ings are somewhat surprising insofar as sports that al., 2004). Data from the US Catastrophic Injury have a perception of high injury risk (e.g., boxing) Registry suggests that the incidence of catastrophic have surprisingly few fatalities, whereas aquatic head and spinal cord injury has been dropping since sports have relatively high fatality rates (Table 11.2). the late 1960s and the effect of the introduction of Most commonly played sports (with the excep- rule changes (e.g., mandatory helmet use, banning tion of equestrian sports) have relatively low fatal- spear tackles) in the 1970s led to no appreciable ity rates and although a fatal event may expose an change in the downward trend of injury rates. underlying anatomical or physiological abnormal- Even though the overall rate of spinal cord ity in the individual concerned there is no conclu- injury in rugby is low, there is a likely risk in rugby sive evidence that pre-event screening (e.g., MR or associated primarily with the tackle and scrum. CT brain scans in boxers) will prevent fatalities. Preventing injuries to the head and cervical spine 177

Table 11.2 Sport-related fatalities in England and Table 11.3 Summary of intrinsic and extrinsic risk Wales. factors in sports concussion.

Sport Fatality rate1 Proposed risk factors Comments

Climbing/mountaineering (excl. hiking and fell Ͼ793 Intrinsic factors walking) Age Confounding factors include (a) Ͼ Air sports 640 increased exposure with increasing Motor sports 146 age and (b) potential mismatch of Water sports/windsurfi ng (excl. sailing and 67.5 ability players in junior competitions. fi shing) Genetic predisposition The current literature is based largely Sailing/yachting 44.5 on studies involving case series and Fishing 37.4 retrospective designs in patients with Horse riding (excl. hunting and polo) 34.3 moderate to severe head trauma. Rugby (union and league) 15.7 Boxing/wrestling 5.2 In studies where potential confounding Football (Soccer) 3.8 factors are controlled (e.g., age, GCS Cricket 3.1 score on admission, neurosurgical management), no association is found 1Fatality rates per 100,000,000 occasions (days) of participation. between apolipoprotein E4 genotype and outcome (Nathoo et al., 2003). Behavior (“risk Use of protective equipment such compensation”) as helmets, may result in higher risk Key risk factors: how to identify taking behavior. athletes at risk Extrinsic factors Characteristics of the The main confounding factor is ground playing surface hardness, which may impact on speed In general, risk factors for injury can be classifi ed of the game and subsequent forces of into either intrinsic or extrinsic (Meeuwisse, 1991; collisions and risk of contact injuries. Milburn, 1993). Intrinsic or internal factors relate Playing position The common trend is that positions to innate qualities of the individual such as their of highest risk tend to refl ect those in which collision rates and velocity age or genetic make-up. Conversely, extrinsic fac- of impact are highest. tors are those related to the environment. Analysis Level of play Confounding factors include (a) of the epidemiological literature reveals a number increased potential for mismatch of of risk factors, which may be associated with player size and ability at some lower increased risk of sports concussion (Table 11.3). levels and (b) modifi ed rules, which Other than for sports concussion, there is surpris- may limit player contact. ingly little published prospective risk factor analy- Biomechanics of head Signifi cant limitations include (a) not sis for catastrophic head and neck injury. impact (site, closing all concussions are clearly seen on velocity, and duration video footage and (b) mathematical of impact) assumptions are made in estimates of acceleration. Injury mechanisms Previous injury Most studies rely on retrospective recall of concussion, which is known to be inaccurate. Furthermore, General important confounding factors such as style of play (e.g., tackling Head and cervical spine injuries in sport arise technique) are often overlooked. mainly due to impacts either with opposing players, the ground or equipment. Participants are exposed to impacts in many sports, for example, football The mechanics of head and cervical spine injuries (of all types), projectile sports (cricket, baseball, have been studied extensively using mathematical, and hockey), high-speed winter sports, aerial sports experimental, and observational methods. These (gymnastics), martial arts, and wrestling. studies arose initially out of the need to prevent 178 Chapter 11 blunt trauma amongst road users and to assess the Factors that may give rise to injury risks in the effects of pilots operating in environments with tackle include: high tackles; high velocity tack- high “g forces.” Due to the recognition that sports les; tackles in which the tackler may have been in participants experience many similar injuries to the peripheral vision of the ball carrier; “big hits” road users and that the loading patterns can be in which the ball carrier is tackled by more than similar, there has been a transfer of knowledge and one player (“grapple” tackle is an example of a theoretical approaches into sport. controversial multiplayer tackle in rugby league) In simple terms, the head and neck are injured (Figure 11.1); and, a general lack of skill for the due to exposure to forces that exceed the “strength” tackler. Apart from high tackles and spear tackles, of the brain, skull, blood vessels, and vertebrae. The where the ball carrier is speared head fi rst into the magnitudes of the force and/or other relevant char- ground, the other types of tackle are legal. acteristics, moment, and acceleration, are determined largely by the energy transfer in the impact. Biomechanics of head injury Other factors are important such as, anatomical point of impact, the shape and stiffness of the How do head impacts in motor vehicle accidents impacted/impacting object, the direction of load- compared with those in football? It is very diffi - ing; amount of translational and/or angular motion cult to measure or simulate the complex dynamics of the head, and, for the neck, the presence of axial of these real-life impact events because of energy loading. The strain that results from these forms attenuation by muscle, joint, or connective tissue of loading is the primary cause of injury. However, forces applied through the neck to the head, and strain is diffi cult to measure in these situations. soft tissue deformation. The tackle in rugby, Australian and American A number of studies using video analysis, fi nite ele- football, and body checking in ice hockey are asso- ment analysis and injury modeling have attempted ciated with risks of minor to severe impact injury, this in both Australian and American football. The including spinal cord injury. In rugby, approxi- basic biomechanical injury mechanisms however, mately half of all injuries arise in the tackle. are the same, namely; forces applied directly to the

Figure 11.1. Examples of “grapple tackles” in rugby league where multiple opponents tackle the ball carrier and attempt to get their arms around the neck while fl exing the head forward Preventing injuries to the head and cervical spine 179 head or via the trunk and neck accelerate the head whereas the probability of skull fracture or intrac- producing internal stresses within the brain, which ranial haemorrhage becomes very high with accel- in turn may result in anatomical or physiologi- erations greater than 200 g. Angular acceleration has cal injury. The resultant brain injury is related to been associated with axonal injury and bridging vein the magnitude of the impact force, the location of rupture that leads to subdural hemorrhages. Strain impact and the resultant head and brain accelera- rate and intracranial pressure effects during impacts tion. Loading of the skull can deform it leading to have also been identifi ed as possible causes of brain fractures, brain contusions, pressure effects, and/or injury. These are diffi cult to measure directly, but can intracranial hemorrhages. be approximated using computer simulations. Interestingly, biomechanical data from sports head injury studies show that in the majority of impacts Biomechanics of spinal cord injury the resulting head accelerations are not trivial but they are lower than those observed in motor vehi- Sport-related spinal cord injury is often due to a com- cle accidents. Linear head accelerations in the order bination of axial compression of the cervical spine and of 100 g are associated with concussion in sport, either fl exion or extension (Figure 11.2). The resultant

(a)

(b)

Figure 11.2. Spinal injury mechanisms: (a) the key mechanism in sport-related cervical spine injuries is axial load and forward fl exion of the neck as illustrated in a diver; (b) Axial load and forward fl exion of the neck results in vertebral compression and anterior wedging of the vertebral bodies 180 Chapter 11 force compresses the vertebral segments and if the method. For these methods to be successful, they tolerance of the vertebrae is exceeded, a “burst frac- must either be able to minimize the energy involved ture” and/or uni-/bi-facet dislocation occurs which in impacts and collisions or reduce the forces applied then damages the cervical spinal cord through direct to the body to levels that can be tolerated without compression. injury. In the context of formal sports it is possible Examples of sport-specifi c mechanisms are given to eliminate some injury risks by pre-crash measures; later. elimination or substitution of hazards, or engineering methods. Sensible removal of structures from the playing fi eld, and the provision of barriers between The rugby scrum the playing fi eld and spectators are obvious engi- The rugby scrum has received substantial attention neering methods for preventing injuries. over the years with regard to spinal cord injury. A rugby scrum consists of two opposing packs of Administrative controls (Laws and eight players divided into the three front row, two Rules) back row, and three “loose” forward. The front rows of each team’s scrum pack engage through their Rules are one of the most common methods used heads and shoulders in a forceful driving motion. to prevent injury, however there have been few This can result in high axial compressive neck structured intervention studies that have identi- forces combined with a bending moment and/or fi ed the benefi ts associated with specifi c rules. If shear forces. During the 2003 Rugby World Cup the rules are not followed, for example, spear tack- there was one case of cervical dislocation during a ling, illegal scrum engagement, or high tackles, the scrum engagement that was a career-ending injury. enforcement of the rule occurs after the potential Milburn et al. measured the forces applied to injurious event. Post-injury penalization of players an instrumented scrum machine, and found that might serve to prevent the illegal play in conjunc- the total horizontal forward force on engagement tion with a pre-injury explanation of the rules, ranged between 4.4 kN for high school players and their rationale, and development of a safe culture. 8 kN for the Australian national team (Andersen Body checking in ice hockey, especially involv- et al., 2004). After the initial engagement, the sus- ing the head, has led to a concern that this form of tained force reduced by approximately 20%. The contact should be eliminated through rule changes forces on engagement have the potential to exceed due to its association with head injury. As with axial neck load and bending moment tolerance lim- spear tackling in American football, which was its. As a result, scrum laws for under 19 year olds are made illegal, there is a view that the use of helmets now designed to eliminate an impact on engage- has increased hazardous play due to players’ percep- ment and permit each front row to orient itself well, tions that they are at a lower risk of injury, often thus reducing neck loads. No study has reported referred to as risk compensation. In American foot- on the effectiveness of the “under 19 law,” although ball, the intentional use of the helmet or faceguard it is widely viewed as being successful and these as the primary point of contact has also been made principles are infl uencing future developments in illegal. Apart from reducing tackle-related injuries the scrum. through rules, no study has reported on the effects of tackle training as a method for preventing injury. Head injury in football (soccer) has been inves- Head and neck injury prevention tigated recently. While heading the ball does not appear to cause concussion per se, the contest for the ball in the air does. During the contest, players Injury prevention methods have been catego- can be struck in the head by the opponent’s elbow, rized under headings drawn from Haddon’s Matrix shoulder, or head, causing injury (Figure 11.3). (Table 11.4). Examples from the literature have Approximately 50% of all concussions were attrib- been used to demonstrate the effectiveness of each utable to this mechanism (Cantu, 2000). As a direct Preventing injuries to the head and cervical spine 181

Table 11.4 Injury prevention matrix applied to sporting head and neck injury prevention: potential measures to prevent injuries.

Pre-impact Impact Post-impact

Athlete Tackling technique Technique: Good head position in Provide appropriate medical care Neck strengthening tackle, good body posture in Education Preparticipation screening scrum engagement Correct rehabilitation Surroundings Preparation and inspection of Improve padding of goalposts Access for emergency medical playing area and surface Develop low impact sideboards coverage

Equipment/ Training Improve energy attenuation of First-aid equipment other athletes Availability of personal protective helmets/head protectors and Spinal stretcher equipment mouthguards Ambulance Improve impact characteristics of ball Teach opponents to disengage if spinal injury is called Administrative Medical review Enforcement of rules Removal of player from ﬁ eld Player exclusion rules and return to Post-match penalization of play guidelines dangerous player Team culture, competitiveness, risk Injury management guidelines awareness and compensation Rules of the game

Preparticipation screening for head and neck injury

Unlike most sporting injuries, head and neck injuries do not have clear-cut risk factors that have been conclusively shown to infl uence either incidence or the outcome of injury (Table 11.3). Because of this most “risk factors” are theoretical in their application. Preparticipation screening while commonly advocated relies more on clinical common sense than the weight of scientifi c evidence. One such method for preventing head and neck injury requires participants to undergo medical screening programs to identify players at risk of injury due to anatomical abnormalities (e.g., MR or CT brain scan), pre-existing brain injury (e.g., neuropsychological testing), or genetic markers (e.g., ApoE). Although intuitively sensible, it is important to realize that excluding player partici- Figure 11.3. Arm to head contact is the cause of over 50% pation based on this approach may not be scien- of all concussions in football (soccer) tifi cally or medicolegally defensible. In some situations, congenital spinal canal steno- result of this research, FIFA modifi ed the playing sis has been postulated as a risk factor for cervical rules before the 2007 World Cup to make contact cord injuries. Although the risk of future cord injury to an opponent’s head with the elbow/upper arm may be increased when canal stenosis is present and during such heading contests a “red card” offence. the athlete has previously sustained a cord injury, 182 Chapter 11 this increased risk cannot be quantitated with any Recent published meta-analysis studies of pedal cycle certainty (Ackery et al., 2007). Furthermore, the risk helmets in transport and recreation have confi rmed of future cord injury in an asymptomatic athlete the fact that light weight helmets are effective in pre- with canal stenosis is unknown at present. Advice venting head and facial injuries in cyclists. regarding the risk of injury in this latter situation In some sporting competitions it has become man- is at best anecdotal and no intervention studies are datory to wear a helmet and/or faceguard, for exam- reported in the literature. ple, baseball, softball, American football, ice hockey, as well as competitive alpine skiing and snowboarding. Helmets in American football and ice hockey Training have evolved from padded headgear to helmets Training to improve strength, fi tness, individual comprising a hard shell, a liner, and a faceguard. and team skills is an accepted part of sport. While Canadian and NOCSAE standards for ice hockey and training programs have been shown to reduce football helmets, respectively, were established in the lower limb injury, for example, the benefi ts of neck early 1970s. Recently, there has been much debate strengthening, skills or fi tness on reducing head over the use of padded headgear in soccer. and neck injury have not been formally addressed. Helmets are designed to attenuate the impact Considering the high associations between body energy and distribute the impact force applied to contact and injury in American football, rugby, the head. If a helmet can reduce the head impact and ice hockey, it is possible that skills may theo- force and head’s acceleration to below relevant tol- retically reduce injury. Improving tackling skills in erance levels and under sport-specifi c impact sce- rugby, for example, head placement, may elimi- narios, then a helmet can function to reduce the nate some accidental head impacts. Skills to track risk of brain injury. a ball, avoid ball contact, and mishits may also The results of published studies show that all of help to reduce neck and head injury, however they the currently available commercial padded headgear have not been formally assessed. for rugby and Australian football has a very limited ability to reduce concussive impact forces based on existing head injury models. Even if the more gen- Environment: ground hardness and erous injury thresholds are applied to the data, all surface headgear tested lose any protective capacity once the impact energy is greater than 20 J. This is refl ected Australian Rules Football is a fast, kicking and run- in randomized controlled trials of headgear in rugby ning game played at professional and amateur lev- and Australian football showing a lack of effi cacy in els across Australia and associated with a high rate concussion prevention with soft-shell helmets. of concussion (Table 11.1). Recent studies have Studies of the effectiveness of helmets in sports debated whether ground hardness is a direct factor where the use (other than in alpine racing) is not in the etiology of injury or whether it indirectly mandatory are emerging (Table 11.5). contributes to higher injury rates as it enables While alpine sport injuries appear to be increas- higher running speeds and higher energy impacts. ing over time, the use of helmets to prevent head With regard to direct head impacts and concus- injuries is associated with a 22–60% reduction in sion, various studies have noted signifi cant differ- head injury rates (McCrory & Turner, 2005). The ences in the impact energy attenuation properties greatest limitations to the widespread application of grass compared to artifi cial surfaces. of protective helmets in these sports are the lack of an internationally accepted helmet standard, Personal protective equipment: the availability of helmets and the variable fi tting helmets of helmets, especially with children. Protective equestrian helmets are also widely Helmets and padded headgear are used in many recommended. Such helmets need to be certifi ed projectile and contact sports to prevent head injury. to an appropriate materials testing standard. At Preventing injuries to the head and cervical spine 183

Table 11.5 Levels of evidence regarding helmet effectiveness.

Sport Effect of helmet Level of Comments use on concussion evidence incidence

American Inconclusive III football Pedal cycling Reduction I Ecologic or observational only Ice hockey No change II Cricket Unknown IIII Lab evidence only Rugby No change I High-quality RCT Skiing Reduction II Several high quality case control studies Australian Unknown II One underpowered study only football Soccer No change III Observational only Equestrian Unknown III Indirect evidence only

present, regulatory authorities mandate the use the data from football (soccer) and Australian foot- of helmets and body protectors in professional ball suggests that the currently available helmets competition. It is recommended that an approved are unlikely to reduce concussion incidence. safety helmet be worn at all times when mounted. Studies of the effectiveness of cricket helmets The British Standard (EN 1384.1996) is designed for have been confi ned to the laboratory and indicate competitive riding and is compulsory for profes- that the level of protection is greatly reduced with sional jockeys and similar standards for horse rid- high-speed ball impacts. ing helmets exist in other countries. Interestingly, since helmets were made compulsory for professional jockeys in 1993–1994, no signifi cant changes Personal protective equipment: in concussion rates have been observed. The num- mouthguards and face shields bers of fatal brain injuries over the same time The use of correctly fi tting mouthguards and face period are too small to be adequately analyzed in masks can reduce the rate of dental, facial, and this regard. mandibular injuries. In the case of face shields, Indirect evidence exists that head protectors there is evidence that they also reduce the rate of may play a role in injury reduction at least in non- concussion whereas randomized controlled trials professional equestrian riders. Both United States have demonstrated that mouthguards have lit- and United Kingdom data showed a fi vefold drop tle or no effect on reducing concussions and any in horse-related injury presentations between 1971 suggested benefi t for the prevention of brain and 1992, due largely to a reduction in head injury injury is largely anecdotal. presentation. Although not a causal relationship, this change was associated with an increase in helmet use over the same time period. Strategies Equipment: baseball to increase helmet use in riders have been studied extensively (Marshall et al., 2003). In baseball, softer balls have been used to reduce Research to date, both fi eld and laboratory, indi- the risk of head injury in comparison to standard cates that padded headgear (soft-shell helmets) balls. Marshall et al. observed a 28% reduction in does not reduce the incidence of concussion or the risk of injury in baseball for games using the serious head injury in Rugby Union football how- reduced impact ball compared to the standard ball ever it seems to reduce superfi cial injuries. Similarly (Nathoo et al., 2003). The softest impact ball was 184 Chapter 11 observed to be associated with the lowest risk of qualifi cations (e.g., AMST, EMST) and training to injury (48% reduction in risk) and the authors deal with them. They must have all the appropriate reported on a study noting that adult and child equipment to hand (hard collars, sandbags, lifting players found it diffi cult to identify the differences frame, and/or a spinal board) and have a method of between standard and safety balls in pitching, rapid disposal on site (paramedic ambulance or hel- throwing, and batting. icopter) to an appropriate hospital (i.e., with neurosurgical trauma expertise). Administrative bodies supervising sideline doctors need to ensure that all Neck muscle strengthening medical staff have the appropriate and up-to-date It is often suggested that neck muscle condition- qualifi cations. ing may be of value in reducing impact forces Athletes and their health care providers must be transmitted to the brain. Biomechanical concepts educated regarding the detection of concussion, its dictate that the energy from an impacting object clinical features, assessment techniques and princi- is dispersed over the greater mass of an athlete if ples of safe return to play. Methods to improve edu- the head is held rigidly. Although attractive from cation including various web-based resources (e.g., a theoretical standpoint, there is little scientifi c www.concussionsafety.com), educational videos, support for this viewpoint and no prospective outreach programs, concussion working groups, published studies to support this approach. Video and the support and endorsement of peak sport analysis of concussive injury seen in Australian groups such as FIFA, IOC, and IIHF. football, rugby and soccer demonstrates that The promotion of fair play and respect for oppo- approximately 95% of concussive impacts are an nents are ethical values that should be encouraged accidental part of play and the players concerned in all sports and sporting associations. Similarly were unaware of impending impact and hence coaches, parents, and managers play an important unable to tense their neck muscles in an attempt part in ensuring these values are implemented on to withstand the impact. This same issue may the fi eld of play and hopefully these may play a apply to protecting the spine. role in injury prevention.

Secondary injury prevention: post-impact measures Take-home message

The role of injury prevention in the post-impact phase has not been adequately addressed in the Head and neck injury is common across all sports. published literature. It is intuitively likely that Some sports (such as equestrian sports) have rela- correct fi rst-aid or paramedical management will tively high risks for participants. By contrast cata- reduce the risk of head or spinal cord injury com- strophic injury is rare. Despite the signifi cance and plications. The management of the concussion or cost of head and neck injury, there have been few mild traumatic brain injury itself at best follows formal evaluations of injury prevention methods. expert consensus guidelines (Level III evidence) in Approaches that are considered successful or have the absence of scientifi cally tested management been proven to be successful in preventing injury strategies. include: modifying the baseball; implementing As the ability to treat or reduce the effects of helmet standards and increasing wearing rates concussive injury after the event is minimal, edu- in cycling, ice hockey, equestrian sports, and ski- cation of athletes, colleagues, and those working ing and snowboarding; use of full face guards in with them as well as the general public is a main- ice hockey; changing rules associated with body stay of progress in this fi eld. contact; and, implementing rules to reduce the When head and cervical spine injuries are impact forces in rugby scrums. Soft-shell helmets expected, the medical staff must have appropriate and padded headgear appear in current designs Preventing injuries to the head and cervical spine 185 to make little difference to rates of concussion. Meeuwisse, W.H. (1991) Predictability of sports injuries. Neck injury has been addressed through laws What is the epidemiological evidence? Sports Medicine and skill development, with little formal evalua- 12, 8–15. Milburn, P.D. (1993) Biomechanics of rugby union tion. Epidemiological, medical, and human fac- scrummaging. Technical and safety issues. Sports tors research methods are required in combination Medicine 16, 168–179. with biomechanical and technological approaches Nathoo, N., Chetry, R., van Dellen, J.R., Connolly, C., to reduce further injury risks in sport. Naidoo, R. (2003) Apolipoprotein E polymorphism and outcome after closed traumatic brain injury: infl uence of ethnic and regional differences. Journal of Neurosurgery 98, 302–306. References

Ackery, A., Hagel, B.E., Provvidenza, C., Tator, C.H. Further reading (2007) An international review of head and spinal cord injuries in alpine skiing and snowboarding. Injury Prevention 13, 368–375. Cantu, R. (Ed) (2000) Neurologic Athletic Head and Spine Andersen, T., Arnason, A., Engebretsen, L., Bahr, R. Injuries. Philadelphia, WB Saunders & Co. (2004) Mechanism of head injuries in elite football. Cantu, R.C., Aubry, M., Dvorak, J., Graf-Baumann, T., British Journal of Sports Medicine 38, 690–696. Johnston, K., Kelly, J., Lovell, M., McCrory, P., Aubry, M., Cantu, R., Dvorak, J., Graf-Baumann, T., Meeuwisse, W., Schamasch, P., Kevin, M., Bruce, S.L., Johnston, K., Kelly, J., Lovell, M., McCrory, P., Ferrara, M.S., Kelly, J.P., McCrea, M., Putukian, M., Meeuwisse, W., Schamasch, P. (2002) Summary McLeod, T.C. (2006) Overview of concussion and agreement statement of the First International consensus statements since 2000. Neurosurgical Focus Conference on Concussion in Sport, Vienna 2001. 21, E3. Recommendations for the improvement of safety Cantu, R.C., Herring S.A., Putukian, M.; The American and health of athletes who may suffer concussive College of Sports Medicine. (2007) Concussion. New injuries. British Journal of Sports Medicine 36, England Journal of Medicine 356, 1787. 6–10. Dvorak, J., McCrory, P., Kirkendall, D.T. (2007) Head Cantu, R. (2000). Cervical spine injuries in the athlete. injuries in the female football player: incidence, Seminars in Neurology 20, 173–178. mechanisms, risk factors and management. British Fuller, C.W., Brooks, J., Kemp, S. (2007) Spinal injuries in Journal of Sports Medicine 41, i44–i46. professional rugby union: a prospective cohort study. Grindel, S., Lovell, M., Collins, M.W. (2001) The Clinical Journal of Sport Medicine 17, 10–16. assessment of sport-related concussion: the evidence Levy, M., Ozgur, B., Berry C. (2004) Analysis and behind neuropsychological testing and management. evolution of head injury in football. Neurosurgery Clinical Journal of Sports Medicine 11, 134–144. 34, 649–655. Guskiewicz, K.M., Bruce, S.L., Cantu, R.C., Ferrara, M.S., Lyens, R., Lefevre, J., Renson, L., Ostyn, M. (1984) Kelly, J.P., McCrea, M., Putukian, M., McLeod, T.C.; The predictability of sports injuries: a preliminary National Athletic Trainers’ Association (2006) Research report. International Journal of Sports Medicine 5, based recommendations on management of sport 153–155. related concussion: summary of the National Athletic Marshall, S., Mueller, F., Kirby, D., Yang, J. (2003) Trainers’ Association position statement. British Journal Evaluation of safety balls and faceguards for of Sports Medicine 40, 6–10. prevention of injuries in baseball. Journal of the Guskiewicz, K.M., Marshall, S.W., Bailes, J., McCrea, M., American Medical Association 289, 568–574. Harding Jr., H.P., Matthews, A., Mihalik, J.R., Cantu, McCrory, P., Turner, M. (2005) Equestrian injuries. R.C. (2007) Recurrent concussion and risk of Medicine and Sport Science 48, 8–17. depression in retired professional football players. McCrory, P., Johnston, K., Meeuwisse, W., Aubry, Medicine and Science in Sports and Exercise 39, 903–909. M., Cantu, R., Dvorak, J., Graf-Baumann, T., Kelly, Iverson, G. (2007) Predicting slow recovery from J., Lovell, M., Schamasch, P. (2005) Summary and sport-related concussion: the new simple-complex agreement statement of the 2nd International distinction. Clinical Journal of Sport Medicine 17, 31–37. Conference on Concussion in Sport, Prague 2004. Johnston, K.M., McCrory, P., Mohtadi, N.G., British Journal of Sports Medicine 39, 196–204. Meeuwisse, W. (2001) Evidence-based review of 186 Chapter 11

sport-related concussion: clinical science. Clinical McCrory, P., Johnston, K. M., Mohtadi, N.G., Journal of Sport Medicine 11, 150–159. Meeuwisse, W. (2001). Evidence-based review of McCrory, P., Collie, A., Anderson, V., Davis, G. (2004) sport-related concussion: basic science. Clinical Can we manage sport related concussion in children Journal of Sport Medicine 11, 160–165. the same as in adults? British Journal of Sports Medicine 38, 516–519. Chapter 12 Preventing tendon overuse injuries Jill Cook1, Mads Kongsgaard2, Karim Khan3 and Michael Kjær4

1Centre for Physical Activity and Nutrition Research School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia 2Institute of Sports Medicine, Bispebjerg Hospital, Copenhagen, Denmark 3Professor, Center for Hip Health and Mobility, University of British Columbia, Vancouver, Canada 4Department of Rheumatology, Institute of Sports Medicine, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark

Table 12.1 Prevalance of tendinopathy at various Introduction anatomical sites according to sport.

Sport Anatomical region of Prevalence Tendons, force transducers interposed between tendon muscles and bones, transmit the force of muscle Running Achilles/iliotibial 10% of runners contraction to bones to allow movement. Optimal band/fascia plantaris tendon function is required for optimal perform- Football Achilles 5–10% of all elite players ance. Tendons are subjected to large mechanical Volleyball Patella 55% of elite-players forces during movement but healthy tendons are Basketball Patella 45% of elite players well adapted to this peak demand. Track and Patella/Achilles 10% of elite athletes fi elds Despite this peak load tolerance, tendon overuse Badminton Achilles/patella 5% of all players injury (tendinopathy) is one of the most frequent Handball Supraspinatus/other 5% of elite players injuries among elite and recreational athletes. Such rotator cuff overuse injuries most often affect tendons such as Baseball Supraspinatus/other 20% of all players the Achilles, patellar, or supraspinatus tendon (Table rotator cuff 12.1). In sports characterized by forceful and explo- The numbers reported are estimates based on the studies sive muscle contractions, the prevalence of patellar available. tendinopathy can reach 45–55% in populations of jumping athletes such as elite volleyball and basketball players. The prevalence of Achilles tendin- pain in most cases. Tendons that rupture are often opathy is also considerable in a variety of different painfree, but have an extensive pathology and the sports such as running (about 10% of all athletes) force imposed on them is greater than the tendon and different ball games (e.g., football). Overuse integrity (Kannus & Jozsa, 1991). The mechanisms injuries in the upper limb occur in athletes (throw- of tendon injury have not been identifi ed and this ing and racquet sports), but are also prevalent in an greatly limits the ability of coaches and clinicians older population, particularly manual workers. to prevent and treat tendon injuries. Overuse tendon injury presents as tendon pain, In tendinopathy, where so little is known about but tendon pathology and tendon pain can develop the basics of the condition, prevention strategies independently; pathology appears to precede are limited and not supported by evidence. To fully comprehend tendon injury mechanisms and the prevention of tendon injuries, it is important Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing to understand tendon structure and function. ISBN: 9781405162449 Thus, we briefl y introduce the structure, function

187 188 Chapter 12 and mechanics of normal tendon. Then we review the etiology of tendinopathy and propose opportunities for injury prevention.

Macroscopic Basic tendon structure tendinosis Normal tendon Increased cellularity (myofibroblasts) All muscles basically have two tendons, a short one at their proximal end (origin of muscle) and a Neovessels somewhat longer one at their distal end (insertion Normal Increased of muscle) underlining that the mechanical proper- tightly bundled matrix protein ties of the tendons will have a great impact upon type I collagen fibrils the function of the entire muscle–tendon–bone complex. Tendons and muscles join, and integrate, at the myotendinous junction—the site where the tendon infi ltrates or interdigitates the muscle body Collagen fibrils in disarray to provide a large contact surface between the two structures. Distally, the tendon joins bone in the Figure 12.1. Bundles of type I collagen fi brils provide osteotendinous junction, a complex transition the load-bearing element of tendon (left side of the from soft to hard tissue. Because the muscle–ten- illustration). These fi brils are embedded in a hydrated viscous proteoglycan-rich substance called the ground don junction is primarily affected in a muscle strain substance. In pathological tendon, the fi brils lose their injury, we will not consider the structure and func- organized structure and disarray is obvious (right side tion of the myotendinous junction in this chapter. of the illustration). Reproduced with permission from The structural design of different tendons varies Clinical Sports Medicine (3/e) page 22, McGraw-Hill substantially; some are short and thick, and oth- Publishing, Sydney, 2007. ers long and thin. Structure depends on the specifi c function of each tendon. Long tendons, such triple helical collagen molecules. The individual as the Achilles tendon, provide the body with collagen molecules inside the fi brils are intercon- energy-returning springs so that movement is nected and stabilized by cross-links thereby secur- energy effi cient. Short, broad tendons, such as the ing the force transduction along the fi bril from quadriceps tendon, serve as pure force-transducers one end of tendon to the other. Although there are for their attached muscles. more than 20 different collagen proteins, tendons Tendon matrix proteins: the building predominantly consist of fi brillar type I collagen blocks of the tendon as well as smaller amounts of other collagen types including type II, III, and V. The various collagen The basic load-bearing element of tendon is col- molecules exhibit different mechanical properties lagen which exists as fi brils (Figure 12.1) that are and the general mechanical properties and func- embedded in a hydrated viscous proteoglycan-rich tion of the whole tendon is therefore highly infl u- substance called the ground substance. Together, enced by the distribution of collagen types. the collagen and the ground substance are called The matrix between the collagen fi brils is com- the extracellular matrix. The various components prised of proteoglycans that are important for the of the extracellular matrix are produced by the alignment of collagen fi bers. Proteoglycans are tendon cells (tenocytes, specialized fi broblasts) hydrophilic (attract water, hence the “swelling” that are elongated spindle-shaped cells and are in injured tendons, see later) and composed of located between the collagen fi brils (Figure 12.1). polysaccharide chains of glycosaminoglycans that If you were to digest tendon collagen fi brils down are bound to protein cores. Proteoglycans act as to their core component you would come across glue between the various collagen networks binding Preventing tendon overuse injuries 189 all the extracellular matrix molecules together. Proteoglycans also regulate matrix assembly and stabilize the extracellular matrix architecture. Further, proteoglycans control the hydration of the extracellular matrix and spacing between collagen fi brils and they bind various growth factors to regulate the mfc tendon milieu. Together with other glycoproteins t such as elastin, fi bronectin, and laminin, the colla- b fc gen and ground substance create a meshwork that does not rely on single molecules but rather on the polymers and networks that the molecules create.

The architecture of the tendon

The structural properties of the collagen fi bril Figure 12.2. The area where the tendon inserts into determine the mechanical properties of the ten- bone the highly specialized “osteotendinous junction.” don. This means that small fi brils increase the elas- There is a transition through four consecutive structural zones: the tendon zone (t), fi brocartilage (fc), mineralized tic properties and larger fi brils increase the strength fi brocartilage (mfc), and bone (b). Note the gradual via greater cross-sectional area and increased num- transition from the tendon tissue to fi brocartilage; more bers of intramolecular cross-links. Approximately rounded chrondocyte-like cells (white arrow) and type II 95% of the fi bers run longitudinally with the ten- collagen (black arrow) increase in prominence to make the don orientation. Tendon fi brils can span the entire tissue appear more “cartilage like.” The fi brocartilage zone is terminated by a distinct border with the mineralized tendon length which implies that the tendon fi brocartilage zone (white arrowhead), this then mechanical properties including strength and stiff- intercalates with bone ness are highly dependent upon the dimensions and composition of the single fi brils. However, surrounds the whole tendon. In areas where ten- other factors such as collagen-type distribution, dons slide relative to adjacent tissues the tendon inter- and intra-fi brillar interactions as well as total may also be enveloped by another loose connec- tendon cross-section are important for the overall tive tissue sheet called the paratenon. Together, function and strength of tendons. the epitenon and paratenon is called the periten- The intrafi brillar cross-linking of collagen mol- don and these structures allow the tendon to glide ecules is an important mechanism for integrity with minimal resistance during movement. between collagen molecules that contribute to The area where the tendon inserts into bone the strength and force-transducing capability of is the highly specialized “osteotendinous junc- the tendon fi bril. Increased cross-linking increases tion.” Here, the viscoelastic tendinous tissue tendon stiffness and elastic modulus, reduces the transfers force to the rigid bone, and there is a failure strain but does not appear to signifi cantly gradual change in the mechanical properties that affect rupture stress. Tendons in older individuals is achieved by transition through four consecutive have an increase in non-enzymatic cross-linking structural zones; the tendon zone, fi brocartilage, in the form of glycation (incorporation of sugar) mineralized fi brocartilage, and bone. The transi- and this increases tendon stiffness. tion from the tendon tissue to fi brocartilage is Several collagen fi brils combine to make up gradual; more rounded chrondocyte-like cells and a tendon fi ber (Figure 12.1). Bundles of fi bers type II collagen increase in prominence to make surrounded by connective tissue (endotenon) the tissue appear more “cartilage like.” Moving comprise a fascicle bundle. The endotenon sur- even further toward bone, the fi brocartilage zone rounding the collagen fi bers and fascicles carries is terminated by a distinct border beyond which blood vessels, nerve fi bers, and lymphatics into the mineralized fi brocartilage zone begins, this the tendon. Loose connective tissue (epitenon) then intercalates with bone (Figure 12.2). 190 Chapter 12

that the elastic energy contributes as much as Tendon mechanics and strength 60% of the energy demand during locomotion. Although a thin and long tendon will assist energy Normal tendons can sustain strain levels up to storage and release, it may be more vulnerable to 20% before suffering initial failure (Figure 12.3). injury. A thicker tendon, which would yield less When testing human tendons in vivo, strain lev- strain energy, would reduce the stress across the els at maximal isometric muscle contractions have tendon and thereby provides the tendon with a ranged 7–18% depending on the tendon inves- greater safety margin. Thus, from an injury pre- tigated. However, the “single strain” condition vention standpoint a presumably healthy (physi- is not the only way that tendons can be injured. ological) hypertrophic tendon adaptation to In sportspeople, tendons are mostly subjected exercise would be advantageous since it will reduce to repeated or prolonged loading. This can cause the amount of stress on the tendon. fatigue damage, even though each single loading Unquestionably, tendons are remarkably strong, a is well below the maximal strength of the ten- tendon with a cross-sectional area of 1 cm2 (approx- don—this is defi ned as fatigue damage. imately corresponding to a normal adult patellar Although a completely stiff structure would pro- tendon) will be able to withstand a tensile load of vide the most effi cient force transduction from 10,000 N or 1000 kg—perhaps 10–15 times body muscle to bone, tendons are quite elastic. Thus, weight. The strength of tendons is related to the when a tendon is loaded and elongated, tendon cross-sectional area (number and thickness of par- force is built up, and energy is stored within the allel fi brils) of the tendon and the tensile quality tendon. This stored energy can be released from of the tendinous tissue (related to factors such as the tendon and utilized to create or prevent joint intrafi brillar cross-links and collagen type distribu- movement. This process conserves energy and tion). In other words, the greater the cross-sectional improves effi ciency of locomotion. It is estimated area, number of cross-links and type I collagen content of a given tendon, the greater loads can be withstood by the tendon before failure occurs if all other factors are equal. The tensile strength of a Elastic non-injured tendon is normally several times higher modulus than the strength of its attached muscle leaving most tendons with a substantial tensile safety margin. However this may not be the case for all ten-

Stress dons during all circumstances. Patellar tendon forces have been estimated to be as high as 8000 N during landing and 9000 N during sprinting and tendon loads in the human Achilles tendon reach 9000 N during running. Thus, some tendons, including the 246 8 Strain (%) patellar and especially the Achilles, may operate close to their maximal strength tolerance. Toe Linear Failure

Tendon adaptation to loading

Figure 12.3. Stress strain curve. There is a “toe” region Mechanical loading stimulates collagen production where strain can increase with little increase in stress. dramatically—a single bout of exercise doubles Then there is a “plastic” region where increased strain the synthesis rate of collagen, and maintains this causes a linear increase in stress. The term “plastic” means elevated level for 2–3 days. This increased synthe- the change is reversible. Beyond the plastic region is sis is dose- or intensity-dependent. In short-term tendon failure—frank rupture of tendon tissue. The elastic modulus is a measure of how “stiff” a tendon is; the stiffer exercise, collagen degradation is also elevated, the tendon, the steeper the slope of the curve resulting in little overall gain in collagen production. Preventing tendon overuse injuries 191

After several weeks of exercise stimulus, degrada- mechanical properties and capacity to sustain load. tion returns to normal levels so that overall colla- The matrix changes are extensive and responsible gen synthesis is increased (Kjær, 2004). for the fundamental decrease in load-bearing These new fi ndings indicate that tendon tissue capacity of the tendon. Ground substance is responds much more dynamically to loading than increased and becomes more cartilage-like in com- previously thought and that intermittent loading position, primarily seen in a change from small to could cause a negative balance between new colla- large proteoglycans with more glycosaminogly- gen formation and collagen degradation. Also, the can chains. Collagen is disrupted, and altered in fact that matrix protein formation is already ele- type from type I to smaller diameter fi bers of type vated after one acute bout of exercise and remains II, and III, and there is an increase in vascularity elevated for around 48 h after exercise indicates and neural ingrowth to the tendon (Figure 12.4). that from “a matrix point of view,” it would be Overall, it seems that extracellular matrix home- suffi cient to train every other day to optimally ostasis is important to maintain normal tendon stimulate matrix tissue of the tendon. Thus, the function and that disruptions of the matrix bal- apparent mismatch between how quickly tissues ance is an early sign or mechanism in tendon such as skeletal and heart muscle adapt to load- injury development. ing, and how frequently such tissues tolerate the We still lack a biomarker in human tendon training stimulus, and the fact that connective tis- that can provide an early warning sign of emerg- sue such as the tendon has a more “delayed” and ing overloading of the tendon. Clinically, tendon slower adaptation pattern, may explain why ten- pathology can be detected by abnormal imaging don can be the weak link in situations of intense (ultrasound or MR) (Figure 12.5). However, the training or overloading. correlation between pain and abnormal imaging Although physical training is associated with a is poor; tendons with abnormal imaging are not chronic elevation of collagen turnover, it is not always painful, likewise tendons that appear nor- clear to what extent this leads to net collagen syn- mal to imaging can be painful. thesis and tendon growth. Although trained men (but not trained women) have greater Achilles tendon cross-sectional area than their untrained Mechanism of tendon overuse injury counterparts, 9 months of running training did not increase the cross-sectional area of the Achilles tendon. As training strengthens tendon mechani- Despite the high incidence and prevalence of tend- cally, it is likely that several factors other than just inopathies the exact etiology remains elusive. It is, the amount of collagen in the tendon are impor- however, generally accepted that overuse injuries tant in the training-induced adaptation of healthy are related to repetitive tensile loading and strain tendon in humans. of the tendon. Thus, a tendon overuse injury Some investigators have suggested that endur- implies an injury in response to repeated strains ance training results in qualitative changes above a certain threshold. The response is driven (improved tissue mechanics) but not quantitative by cell detection of load that causes increased pro- (increased tendon size) changes, whereas other tein production in the cell. Eventually the injury investigators have concluded that tendons react to will manifest itself by increased ground substance, endurance training by both quantitative and qual- fi bril disorganization, neovascularization and poten- itative augmentations. tially pain and swelling. As mentioned earlier, sporting activities that Tendon pathology utilize energy storage capacities of the tendon or forceful eccentric components may maximally Tendon pathology induces dramatic changes in ten- challenge the tendon’s fatigue resistance and don structure, with changes in both the cells and reparative capacity especially if there is little recov- the extracellular matrix that results in poorer ery time between exercise sessions. With enough 192 Chapter 12

Ict

(a) (b)

Figure 12.4. This photomicrograph compares neural tissue in (a) normal patellar tendon and (b) injured patellar tendon. In the side affected by chronic tendinopathy, there is increased spread and sprouting of nerve ﬁ bers (arrows) and they are not restricted to the loose connective tissue (lct) around the tendon. They invade the tendon itself (labeled a “t” in the image). Reproduced with permission from Øystein Lian, Johan Dahl, Paul W. Ackermann, Frede Frihagen, Lars Engebretsen, Roald Bahr. Pronociceptive and Antinociceptive Neuromediators in Patellar Tendinopathy. American Journal of Medicine 34, 1801–1808 (2006). Published by Sage Publications.

The development of tendinopathy may also be related to the structural properties of the tendons. Both the Achilles tendon and the patellar tendon have a non-uniform cross-sectional area distribution along their length and that the regions where tendinopathy most often occur in these tendons have the narrowest cross-sectional area. Thus, tendon overload injuries may arise at sites of stress concentrations (high force per area) in the tendons at these specifi c regions. However, it is unlikely Figure 12.5. Tendon pathology can be detected as a that tendon stress is the sole factor in the etiology hypoechoic appearance when the tendon is scanned using gray scale ultrasound of tendinopathies. The majority of tendinopathies occur in the tendon closer to the attachment to bone. The tissue at the osteotendinous junction display inferior modulus and maximum stress com- time between bouts of acute loading, tendons pared to mid-tendon tissue. recover, but stress reapplied without suffi cient recovery may lead to injury. This reminds us of the fi ne line between optimal loading for adaptation and loading that puts the tissue under too Risk factors for tendon overuse injuries much reparative stress. It could be suggested that the tendon fi broblast increases protein synthe- Age sis in response to mechanical loading, but that this cannot increase further with higher-intensity The prevalence of tendon pain and rupture exercise. This might explain why too much exer- increases with age, and this may be due to changes cise (e.g., excessive jumping) can result in a sub- in tendon structure and mechanics. As tendons optimal adaptation of the tendon and subsequent age they decrease protein content and increase tendinopathy. cross-links, consequently the tendon is stiffer. Preventing tendon overuse injuries 193

Tendons also thicken with age, and an increase in individuals have a substantially higher preva- cross-sectional area may compensate for decreased lence of tendon ruptures than matched Caucasian “quality” of the tendon. Americans (Owens et al., 2007). Younger tendons are also vulnerable to tendon pathology and in the adolescent population the Body composition prevalence of patellar tendon pathology in jumping athletes is similar to adults. At all ages, over- A recent cohort study has demonstrated that waist load can produce pain in an already pathological measurement was associated with patellar tendin- tendon. opathy. This study reported that waist circumfer- ence in males of greater than 83 cm resulted in a Sex 74% probability of morphological tendon abnormalities (via ultrasound), whereas males with The prevalence of lower limb tendinopathy appears waist of less than 83 cm had a 15% probability of to be less in sporting women than among men tendon changes (Malliaras et al., 2007). with comparable training history, men have twice Body mass index has been associated with onset the risk of developing tendon pathology and pain of tendinopathy. Nineteen out of 41 studies in a compared to women (Lian et al., 2005). Possible systematic review showed a signifi cant association reasons for this difference require investigation. with adiposity and tendon health. In those having Candidate hypotheses include that (i) men with rotator cuff surgery there was a strong relationship larger muscles may be able to impose greater loads between body mass index and risk of rotator cuff on their tendons, or subject them to more loading tendinopathy. A longitudinal study showed that cycles, (ii) women’s and men’s tendons have differ- the strongest predictor for developing upper limb ent capacities to adapt to an increased or decreased tendinopathy was a body mass index of greater loading, or, (iii) sex hormones may play a key role than 30. Further research is needed to identify in tendon pathogenesis. the mechanisms for such associations, but like other musculoskeletal conditions it is likely that Genes the mechanisms are more complex than just an increase in load on the tendon (Pottie et al., 2006). Researchers have unraveled the relationship between Achilles tendinopathy and genes for two Range of joint movement proteins: tenascin-C and type V collagen. Certain types of genes (polymorphisms) in both the A decreased range of ankle dorsifl exion range of tenascin-C and collagen V genes were associated movement is associated with both Achilles and with Achilles tendinopathy and this association patellar tendon pathology, and is likely to relate to has been confi rmed in a second population. increased tendon forces with landing. Interestingly, Further research is ongoing, and if the link is plantar fasciitis and Achilles tendinopathy have clearly demonstrated, this may be the fi rst dem- been also associated with an increased range of onstrated (non-modifi able) risk factor for tendin- dorsifl exion. opathy. It is noteworthy that patients with a previous Achilles tendon rupture have a 200-fold Chronic disease risk of sustaining a contralateral rupture (Arøen et al., 2004). This strongly indicates either a genetic Glycation cross-links are increased in subjects with predisposition or other unknown predisposing fac- diabetes, making tendons stiffer and more prone to tors in these individuals. Further evidence to sup- overload. Cross-linking is crucial in order to secure port a strong genetic link is that the incidence of normal tendon function and tensile strength tendon ruptures in western countries far exceeds but increased cross-links and therefore stiffness, that in Africa and East Asia but at the same time it may be detrimental by reducing the strain to tis- has convincingly been shown that Afro-American sue failure. Spondyloarthropathy manifests as 194 Chapter 12 bone–tendon junction disease similar to ath- stop participation. At best, imaging might allow letic tendinopathy. These diseases have systemic the coach or medical practitioner to be aware of and familial links, as does diabetes (especially which athletes are at risk (Fredberg et al., 2007), type 1). In addition, type 2 diabetes is associated plan training so overload is minimal, and monitor with increased abdominal adiposity, and interac- and modify tendon load as necessary. Although tions between risk factors for tendinopathy have this is far from satisfactory, tendon pain and path- not been clarifi ed. ology remain outside the injuries that can be easily controlled. Muscle strength and fl exibility

Muscle strength of the attached muscle has not been clearly shown to be a factor in the onset of Preventing tendon overuse injuries tendon pathology. Athletes who can jump higher have more patellar tendon pathology in some Because tendon pathology appears to result from studies (Lian et al., 2003), other studies do not an interaction between several individual and support this (Malliaras & Cook, 2006). Reduced environmental risk factors, prevention is not muscle fl exibility has been shown to be associated merely a matter of following a single recipe for all with patellar tendinopathy, both the hamstrings athletes. A tendon that is not overloaded will not and quadriceps have been implicated (Witvrouw develop tendinopathy—it appears that repeated et al., 2001). stretch-shortening cycles with body weight over time are required to generate tendon pathology Other factors and pain. However, as individuals appear to have a wide variation in load tolerance, it is not currently The amount of loading has been shown to be possible to provide “research evidence” for a nar- associated with patellar tendon pain and pathol- row, defi ned load that minimizes risk of tendon ogy. The type of fl ooring has also been implicated, overuse injury. a harder fl oor will increase tendon load (Ferretti et al., 1984). Adaptation to loading Take-home message The ability of tendinous tissue to respond to Athletes who load heavily with training in sports mechanical loading of the muscle–tendon unit is and have a big energy storage and release com- of great interest as inadequate adaptations may ponent are vulnerable to tendon pathology. Each promote the development of injury and an ade- sport has its own collection of vulnerable tendons: quate adaptation may reduce the risk of tendinop- the patellar tendon in jumping athletes, Achilles athy despite substantial tendon loading. in running and court sports, and the adductor Tendinous tissue has traditionally been regarded tendons in football players. This vulnerability is as rather sluggish and static with a limited abil- ameliorated or enhanced in individuals by intrin- ity to react and adapt to exercise and training. sic risk factors and a range of other unknown However research has shown that tendinous tissue factors. Coaches are well aware that two athletes is highly capable of adjusting its metabolism to can train identically yet one will develop tendon match an increase in loading and that the tissue pathology and pain and the other will remain can adapt to training. Interestingly, also in tendi- symptom-free. nopathic tendons, regular exercise does result in Although we can identify tendon pathology an upregulation of collagen synthesis, indicating clinically with imaging, this does not allow us that even in a diseased state, tendons benefi t from to predict which athletes will develop pain, and a certain degree of controlled loading (Langberg of these, which will develop pain suffi cient to et al., 2007). Preventing tendon overuse injuries 195

Specifi c types of exercise: high simple protocols for adjusting load. However, energy intensity and strength training storage and release causes tendon pathology, hence it is easy to say if you cycle or swim you are unlikely There has been very little investigation of tendon to get a tensional tendon overload (swimmers may responses and adaptations to intermittent high get compressive overload of the rotator cuff). Outside loads as those seen in jumping, sprinting and of this recommendation, load management becomes heavy strength training. Patellar tendon hypertro- more diffi cult, frequency of load appears important; phy occurs in response to 12 weeks of heavy resist- training more than once in every 2 days does not ance training the increase in cross-sectional area allow the tendon to respond fully to each load stim- occurred at the proximal and distal ends but not at ulus. Nothing is known about modifying volume the mid-tendon (Kongsgaard et al., 2007). This is and intensity of load. A recent study that investi- supported by a study that showed high-resistance gated gradual introduction of running compared to a training reduced tendon pain (Frohm et al., 2007). standard running training program did not fi nd any difference in injury between groups, because of indi- Specifi c types of exercise: eccentric vidual variations in injury susceptibility very large training numbers in such studies may be needed to clearly show if a difference exists (Buist et al., 2008). Eccentric exercise places high load on tendon and it has been used extensively to rehabilitate painful tendons (Kingma et al., 2007). Its use as a pre- Take-home message vention has been investigated only recently and a Because tendon’s response to different kinds of study of soccer players has shown that it did not exercise and loading varies, coaches cannot follow reduce the risk of injury. In fact those with patellar “one-size fi ts all” approach. Tendons possess adap- tendon pathology at the beginning of the season tational capabilities and in most circumstances were more likely to be injured if they did the pre- will adapt adequately to different levels of exer- ventative eccentric exercise (Fredberg et al., 2007). cise if they are given enough time. However, as In a similar study in volleyball players, eccentric tendinous tissue is somewhat slower to adapt than training in season did not improve tendon pain muscle tissue it is suggested that sudden increases (Visnes et al., 2005). or changes in exercise loads and modes should be avoided wherever possible. It would appear pru- Stretching dent for training changes to be prescribed cau- tiously to allow the tendon enough time to adapt Stretching is used to prevent injury, in tendons and recover and prevent the development of the type of stretching may be critical. Dynamic injury. Abdominal fat, lack of fi tness, and certain stretching may be superior to static stretching as biomechanical factors are risk factors for overuse it alters the mechanical properties of the tendons tendinopathy so these should be addressed in (Witvrouw et al., 2007), whereas static stretching active individuals. Imaging (including ultrasound in many tendinopathies will increase the compres- and MR imaging) does not appear to contribute to sive load, known to cause pathological alterations the clinical approach to tendinopathy prevention in tendons. In athletes although static stretching at this stage. may be relevant for the muscle, the best tendon response is to dynamic stretching.

References Adjusting training load

Although overload has been clearly linked to ten- Arøen, A., Helgø, D., Granlund, O.G., Bahr, R. (2004) don pain and pathology, athletes have widely rang- Contralateral tendon rupture risk is increased in ing load tolerance. Thus, we are unable to prescribe individuals with a previous Achilles tendon rupture. 196 Chapter 12

Scandinavian Journal of Medicine and Science in Sports 14, among volleyball players. Journal of Science and 30–33. Medicine in Sport 9, 304–309. Buist, I., Bredeweg, S.W., van Mechelen, W., Lemmink, K.A., Malliaras, P., Cook, J., Kent, P. (2007) Anthropometric Pepping, G.J., Diercks, R.L. (2008) No effect of a graded risk factors for patellar tendon injury among volleyball training program on the number of running-related players. British Journal of Sports Medicine 41, 259–263. injuries in novice runners: a randomized controlled trial. Owens, B., Mountcastle, S., White, D. (2007) Racial American Journal of Sports Medicine 36, 33–39. differences in tendon rupture incidence. International Ferretti, A., Puddu, G., Mariani, P.P., Neri, M. (1984) Journal of Sports Medicine 28, 617–620. Jumper’s knee: an epidemiological study of volleyball Pottie, P., Presle, N., Terlain, B., Netter, P., Mainard, D., players. Physician and Sports Medicine 12, 97–103. Berenbaum, F. (2006) Obesity and osteoarthritis: more Fredberg, U., Bolvig, L., Andersen, N.T. (2007) complex than predicted! Annals of Rheumatic Disease Prophylactic training in asymptomatic soccer players 65, 1403–1405. with ultrasonographic abnormalities in Achilles and Visnes, H., Hoksrud, A., Cook, J., Bahr, R. (2005) No patellar tendons: the Danish Super League Study. effect of eccentric training on jumper’s knee in American Journal of Sports Medicine December 13 [Epub volleyball players during the competitive season: a ahead of print]. randomized clinical trial. Clinical Journal of Sports Frohm, A., Saartok, T., Halvorsen, K., Renström, P. Medicine 15, 227–234. (2007) Eccentric treatment for patellar tendinopathy: Witvrouw, E., Bellemans, J., Lysens, R., Danneels, L., a prospective randomised short-term pilot study of Cambier, D. (2001) Intrinsic risk factors for the two rehabilitation protocols. British Journal of Sports development of patellar tendinitis in an athletic Medicine 41, e7. population. A two-year prospective study. American Kannus, P., Jozsa, L. (1991) Histopathological changes Journal of Sports Medicine 29, 190–195. preceding spontaneous rupture of a tendon. Witvrouw, E., Mahieu, N., Roosen, P., McNair, P. (2007) A controlled study of 891 patients. Journal of Bone and The role of stretching in tendon injuries. British Journal Joint Surgery (American) 73, 1507–1525. of Sports Medicine 41, 224–226. Kingma, J.J., de Knikker, R., Wittink, H.M., Takken, T. (2007) Eccentric overload training in patients with chronic Achilles tendinopathy: a systematic review. British Journal of Sports Medicine 41, e3. Further reading Kjær, M. (2004) Role of extracellular matrix in adaptation of tendon and skeletal muscle to mechanical loading. Physiology Review 84, 649–698. Bahr, R. (2003) Preventing sports injuries. In R. Bahr & Kongsgaard, M., Reitelseder, S., Pedersen, T.G., Holm, L., S. Mæhlum (eds.) Clinical Guide to Sports Injuries, Aagaard, P., Kjær, M., Magnusson, S.P. (2007) Region pp. 41–53. Human Kinetics, Champaign, IL. speciﬁ c patellar tendon hypertrophy in humans Bahr, R. (2007) Principles of sports injury prevention. In following resistance training. Acta Physiologica P. Brukner & K. Khan (eds.) Clinical Sports Medicine, Scandinavia 191, 111–121. pp. 78–101. McGraw-Hill, Sydney. Langberg, H., Ellingsgaard, H., Madsen, T., Jansson, J., Cook, J.L., Purdam, C.R. (2003) Rehabilitation of lower Magnusson, S.P., Aagaard, P., Kjær, M. (2007) Eccentric limb tendinopathies. Clinics in Sports Medicine 22, rehabilitation exercise increases peritendinous type I 777–789. collagen synthesis in humans with Achilles tendinosis. Ljungqvist, A., Schwellnus, M.P., Bachl, N., Collins, M., Scandinavian Journal of Medicine & Science in Sports 17, Cook, J., Khan, K.M., Maffulli, N., Pitsiladis, Y., 61–66. Riley, G., Golspink, G., Venter, D., Derman, E.W., Lian, Ø.B., Engebretsen, L., Bahr, R. (2005) Prevalence Engebretsen, L., Volpi, P. (2008) International Olympic of jumper’s knee among elite athletes from different Committee consensus statement: molecular basis of sports: a cross-sectional study. American Journal of connective tissue and muscle injuries in sport. Clinics Sports Medicine 33, 561–567. in Sports Medicine 27, 231–239. Lian, Ø., Refsnes, P.E., Engebretsen, L., Bahr, R. (2003) Maffulli, N., Renström, P.A.F.H., Leadbetter, W.B. (2005) Performance characteristics of volleyball players Tendon Injuries: Basic Science and Clinical Medicine. with patellar tendinopathy. American Journal of Sports Springer-Verlag, London. Medicine 31, 408–413. Woo, S.L.-Y., Renström, P.A.F.H., Arnoczky, S.P. (eds) Malliaras, P., Cook, J. (2006) Reduced ankle dorsiﬂ exion (2007) Tendinopathy in Athletes. Blackwell Publishing, range may increase the risk of patellar tendon injury Massachusetts. Chapter 13 Implementing large-scale injury prevention programs Randall W. Dick1, Claude Goulet2 and Simon Gianotti3

1Research/Injury Surveillance System National Collegiate Athletic Association, Indianapolis, Indiana, USA 2Department of Physical Education, Laval University, Québec, Canada 3Sport and Road Injury Prevention, Accident Compensation Corporation, Institute of Sport and Recreation Research New Zealand, Faculty of Health and Environmental Science, Auckland University of Technology, New Zealand

participation. In a public health perspective, it Introduction supports the importance of implementing large- scale injury prevention programs. It is well documented that regular sport participa- Implementing large-scale injury prevention pro- tion or physical activity can improve health and grams poses many challenges. Drawing mainly quality of life. Moreover, in combination with a from our experience and from published litera- proper diet and a healthy lifestyle, physical activ- ture in the fi elds of sport and recreational activity ity is an infl uential factor in the control of body injury prevention (see Chapter 2), we have pro- weight. From a public health perspective, the ben- duced a list of fi ve key elements to consider in the efi ts of physical activity are clear. development and implementation of large-scale There is, however, a cost of physical activity— prevention programs. These key elements are namely the burden of injuries. Injuries resulting as follows. from sports and recreational activities are a signifi cant health problem in many countries. There Approach the injury problem at hand is now irrefutable evidence that the sports injury with a multi-dimensional view problem is not restricted to professional sports. For It is essential to analyze any injury problem through more than two decades, about every fi fth unin- a systematic approach and a multi-dimensional tentional injury treated in a health care setting in view (see Chapter 2). It maximizes the prob- industrialized countries has been associated with ability that all possible solutions to the problem sports or physical activity. This makes sport and will be addressed. Based on some of the latest recreational activity injuries probably the most conceptual advances made in the fi eld of injury ironic injury type. On one side, public health prevention, we also suggest that the following authorities are actively promoting regular sport guiding principles be considered in the analy- and physical activity participation. On the other sis process: (1) Consider the cost/benefi t ratio hand, it is known that if not practiced in safe when selecting an intervention strategy; (2) con- environments, sport and recreational activity inju- sider the impact an intervention might have on ries could signifi cantly reduce the public health the nature of the sport; (3) choose interventions benefi ts of regular sport and physical activity adapted to the problem at hand: either inform, convince, or contrive (see Section “Active versus Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing passive measures” in Chapter 2); and (4) Encourage ISBN: 9781405162449 partnership.

197 198 Chapter 13

Beliefs confuse the issue; get the facts of America, by the Accident Compensation Corporation (ACC) in New Zealand, and by the Sport is an area where changes occur slowly because provincial government in the Canadian province of deep-rooted beliefs. You need well-documented of Québec. Each example will incorporate the facts on the injury problem as well as the effects of fi ve key elements previously discussed within the the proposed measures before trying to convince context of the four step injury prevention model the targeted group—whether it be elite athletes, rec- (IPM): (1) describing the magnitude of the injury reational participants or owners of sport facilities. problem, (2) understanding the causes, (3) introducing measures likely to reduce the future risk Work toward a consensus; develop and/or severity of injuries, and (4) evaluating their coalitions effect (Figure 2.1). These examples and approaches should help key stakeholders in sports injury pre- Even if you are in a position to impose mandatory vention to implement effi cient large-scale injury safety measures, make sure you develop strong prevention programs to improve the social and grass-roots support for your intervention. As a health benefi ts of sport participation. sport injury prevention specialist, identify the key stakeholders and work with them on solutions that they are willing to apply. Be prepared to support these partners with information and training. The American National Collegiate Athletic Association model

Recognize the limits of information campaigns; develop back-up The NCAA is an organization of approximately technological systems 1100 colleges and universities established in 1906 to govern athletics competition in a fair, safe, equi- Public awareness campaigns are important, but table, and sportsmanlike manner and to integrate they are not enough. Well-informed people are intercollegiate athletics into higher education. The still human beings; which means that knowledge association conducts its business through a com- does not necessarily result in behavior change. mittee structure made up of diverse representatives One of the most effi cient ways to improve sports from member institutions. Nationally, more than safety is through the modifi cation of the environ- 380,000 student–athletes participate in NCAA ment (see Section “Active versus passive measures” sports that offer national championships. in Chapter 2). Recognizing its organizational health and safety roots, the NCAA has maintained an Injury Try to change the perception that more Surveillance System (ISS) for intercollegiate ath- safety brings less fun letics since 1982. The primary goal of the system is to collect injury and exposure data from a Safety is often perceived as something that will take representative sample of NCAA institutions in fun away from sport and recreational activities. In a variety of sports. Relevant data are then shared fact, safety measures can allow participants more with appropriate NCAA sport and policy commit- enjoyment from their activity by giving them “peace tees to provide a foundation for evidence-based of mind.” In general, outdoor specialists understand decision-making on health and safety issues. The this positive side of safety. Safety is often what makes NCAA model of a sport organization with (1) a their activity possible. We can all learn from their committee structure with the authority to develop attitude toward safety skip line after end of PP. enforce policy, (2) data collections systems such as The aim of this chapter is to present fi ve prac- the ISS to provide an information foundation for tical examples of large-scale programs that have decision-making, and (3) a review process to assess been implemented by the National Collegiate policy effectiveness has been benefi cial in a variety Athletic Association (NCAA) in the United States of injury prevention initiatives. Implementing large-scale injury prevention programs 199

prior to competition, When the actual competition Example 1: Wrestling with weight took place, both opponents generally weighed loss—The NCAA Wrestling Weight signifi cantly more than the designated weight Management Program class they had qualifi ed for the previous day (mean 3.3 kg in one study;Horswill et al., 1994). There The problem (IPM Steps 1 and 2) also could be a signifi cant weight differential between the two individuals (mean 1.5 kg in one In a span of 33 days in late 1997, three collegiate study; Scott et al., 1994) nullifying any competitive wrestlers died while engaging in a program of rapid equity associated with weight class. weight loss. All were in the presence of coaches. 4. Wrestler mindset: Wrestlers believed that self- According to the Centers for Disease Control and discipline, commitment and sacrifi ce they learned Prevention’s (CDC, 1998) review of the cases, the from making weight would help make them better wrestlers were attempting to lose an average of 8 wrestlers. Cutting 3–7% body weight and then pounds over a 3- to 12-h period by wearing rub- regaining it the next day was perceived to allow ber suits and exercising vigorously in hot environ- one to gain a strength and size advantage over a ments. The wrestlers were attempting to lose this “smaller/weaker” opponent. weight AFTER dropping an average 21 pounds over the previous 2–3 months. There were no previous recorded deaths in Working toward consensus: identifying NCAA wrestling associated with making weight the stakeholders but the sport in general had a reputation for rapid In the aftermath of the wrestling deaths, the NCAA and severe weight fl uctuations similar to those joined with other organizations to create a joint reported in these three cases. resolution which said, in part: “Eliminate from wrestling any and all weight control practices which Understanding the facts and the belief could potentially risk the health of the participants.” structure (IPM Steps 1 and 2) Two NCAA committees, the National Wrestling Coaches Association, USA Wrestling, the national The sport of wrestling had a variety of issues to governing body for wrestling and various medi- consider before addressing the problem. cal organizations were involved in the discussions. 1. Established guidelines: Position statements Coaches, student-athletes, exercise physiologists, associated with weight loss in wrestling from athletic trainers, physicians, athletic administrators, organizations such as the American College of sport governing body offi cials, and lawyers were all Sports Medicine (ACSM, 1996) had existed for represented. Since weight cutting mostly occurred many years. The three deaths brought attention to in the practice environment, and could not be regu- weight loss behaviors that, in some cases, had been lated effectively by competition rules, the wrestling contrary to medical guidelines for many years. coach was identifi ed as a key stakeholder. While cer- 2. Safety: The NCAA ISS had shown wrestling as a tain policies could be implemented and enforced, sport at very high risk for injury relative to other the wrestling coach, and his or her attitude toward sports monitored by the system (Agel et al., 2007). weight cutting leading up to competitions, ulti- Many of the injuries may have been directly or mately would determine the success of the program. indirectly associated with improper weight loss practices or their after-effects. NCAA weight management program 3. Competitive equity: Weight was acknowledged components (IPM Step 3) to be the competitive equity variable in the sport of wrestling. Weight classes were established to The NCAA weight management program (Figure assure that opponents were paired against athletes 13.1) was based on four guiding principles: of similar weight. Prior to these fatalities, collegiate • Enhance safety and competitive equity wrestlers were able to make weight at least 24 h • Minimize incentives for rapid weight loss 200 Chapter 13

ents (consensus), a committee structure with the capability to enact and enforce formal policy, and specifi c research to determine policy effectiveness. The NCAA wrestling weight management program has become a model program for the sport and has been accepted by collegiate wrestlers and coaches. The sport has become more fun for participants as the emphasis has switched from weight loss to skill development. In the 2004–2005 academic year, this program involved 224 intercollegiate wrestling programs, touching almost 6000 student-athletes. In 2006 the National Federation of State High School Associations (NFHS) imple- Figure 13.1. The NCAA Wrestling Weight Management Program shows promise for increased safety and mented a similar weight management program competitive equity for wrestling participants of all ages at the United States high school level impacting over 250,000 student-athletes. These programs • Emphasize competition, not weight control show promise for increased safety and competitive • Implement practical, effective, and enforceable equity for wrestling participants of all ages. A simi- guidelines. lar weight management program may be benefi cial Specifi c components included: establishing weight at higher levels of wrestling and in other Olympic classes that better refl ect the collegiate wrestling pop- weight category sports such as rowing and boxing. ulation, establishing a permanent healthy weight class (lean body weight plus at least 5% body fat) early in the season with time to achieve it safely, The New Zealand model establishing weigh-ins as close to the match as possible, eliminating the tools used to accomplish rapid In New Zealand, determining the size and scope of dehydration, and requiring CPR certifi cation of all a particular sport injury problem is relatively simple. wrestling coaches. This is largely due to the existence of a mandatory no-fault 24-h injury scheme providing coverage for Evaluation of the weight management injury treatment and rehabilitation costs. The scheme program (IPM Step 4) is administered by the Accident Compensation To evaluate effectiveness, research investigating the Corporation (ACC). In the last ACC fi nancial year changes in weight and body composition relative (1 July 2006 to 20 June 2007—2006/2007), the 4.1 to performance over the course of the season was million New Zealanders made 422,000 sport and initiated. Research conducted over the entire wres- recreation claims, costing the Corporation $NZ 329 tling season showed that the most successful wres- million. There is no disincentive for making a claim; tlers chose to participate at a body composition people are not discriminated, risk rated or penal- well above the minimum allowable value of 5% ized for the number of claims they make. The cost and that reducing the time between weigh-ins and of claims and the legislation governing the ACC pro- competition was effective in reducing rapid weight vides incentive for investing in large-scale injury pre- loss. A weight management program coupled with vention programs. ACC has a cost-outcome model reducing time between weigh-ins and competition to determine investment levels and programs are was even more effective. expected to provide a return on the investment. ACC currently targets moderate to serious injury claims Discussion for its sport cost-outcome model. Although moderate to serious injury claims may make up only a small The successful NCAA model includes injury sur- proportion of all sport claims, 7.4% in 2006/2007, veillance (facts), input from diverse constitu- they represent around 75% of the cost. Implementing large-scale injury prevention programs 201

course showed that it was not achieving the desired effect, despite early reported results. In 2000, ACC and NZRU formed a coalition to tackle the injuries. ACC data identiﬁ ed neck/back/spine, shoulder, knee, ankle, and leg (excluding knee and ankle) injuries to target in addition to serious spinal injuries. These body parts were predominantly injured in contact situations of the scrum, tackle, ruck, and maul phases of the game. Improving technique in these phases lowers the risk of injury and moderate to serious injury claims. The program targeted community-level (non-professional) 15–44-year-old rugby players due to their impact on the ACC scheme; they represented 34% of the players, but 92% of the rugby moderate to serious injury claim costs. Figure 13.2. The New Zealand Accident Compensation Corporation SportSmart model is a 10-point action plan Understanding the facts and belief for sports injury prevention structure

While there was acknowledgment that the inci- In 1999, ACC developed the SportSmart model, dence of serious spinal injuries needed attention, a 10-point action plan (screening, warm up/cool the NZRU compulsory safety course was widely down, physical conditioning, technique, fair play, viewed as undesirable and was not well received by protective equipment, hydration/nutrition, injury the rugby community. Common reasons included: reporting, environment, injury management) 1. Coaches/referees were volunteers and (Figure 13.2) for sports injury prevention and has were diffi cult to recruit; having to undertake since developed a range of sport-specifi c injury a compulsory safety course was yet another prevention programs based on this model. This commitment on the coaches time. initiative relies on a coalition between ACC and 2. The focus was on the consequences of the respective national sporting body. Two specifi c a serious injury. Highlighting the problem applications of the SportSmart model are discussed had the potential to turn people away from in the following section. coaching/refereeing. 3. Coaches perceived that they knew most of the information imparted in the compulsory course Example 2: The RugbySmart Program— and that it was the same every year. preventing injuries in rugby union In summary, a system to deliver compulsory safety education was in place but it needed to be The injury problem (Steps 1 and 2) made more suitable to the audience to achieve buy-in and acceptance. Rugby Union (rugby) represents the largest percentage (15%) of sport moderate to serious injury Working toward consensus: identifying the claims to ACC. It is also a sport that has been asso- stakeholders ciated with serious spinal injuries. Due to their severity and life changing impact, these injuries By developing a coalition, both groups could draw media attention and focus on to rugby. achieve appropriate outcomes. ACC desired a In 1996, the New Zealand Rugby Union (NZRU) reduction in the number of injuries, as it provided implemented a compulsory safety course for coaches for the cost of rehabilitation and replacement of and referees, with the focus on preventing serious earnings, whereas the NZRU wanted to make the spinal injuries. Analysis of the compulsory safety game a competitive, safe, and popular sport. 202 Chapter 13

The new program, RugbySmart, was developed Having a DVD ensured consistency of delivery based on SportSmart and implemented in the 2001 and supported the facilitator. RugbySmart, like its rugby season with ACC investment. The NZRU com- NZRU predecessor was compulsory for coaches pulsory safety course evolved to RugbySmart and and referees to attend. Team were withdrawn from was repackaged to focus more on causes of injury competition and referees were not assigned games rather than consequences. In addition to NZRU and if they did not attend. While the compulsory edu- Rugby Development Offi cers, coaches and referees cation aspect was appealing to ACC and ensured a also were identifi ed as stakeholders. RugbySmart captive audience, it also created resistance to the targeted coaches and referees as (i) reaching 137,000 program. This was largely overcome by develop- players via coaches/referees was more effective than ing a product that appealed to the coaches and ref- targeting each player directly and more effective erees. For example, promoting correct or winning than relying on clubs and schools and (ii) coaches technique as safe and then demonstrating skills were identifi ed by both players (and coaches) as that focused on the improved technique was a suc- having an important role in injury prevention. cessful strategy. The skills demonstrated were in a straightforward manner, allowing coaches to master them and easily incorporate into trainings. The RugbySmart program (Step 3)

RugbySmart involves the screening of a DVD at a Evaluation of the RugbySmart program compulsory workshop, as originally put in place by (Step 4) NZRU. The DVD contained aspects of the 10-point action plan, with an emphasis on areas where RugbySmart was evaluated in several ways and the injury issues have been identifi ed, such as the results were used to develop the program further, scrum, tackle, and ruck (Figure 13.3). The workshop keeping it fresh and relevant. NZRU is one of the few was conducted by Rugby Development Offi cers (for sports in NZ to have an accurate and reliable player coaches) and Referee Education Offi cers (for ref- registration system, providing a moderate to serious erees), and these positions were funded by NZRU. injury claims rate per 100,000 players to determine the effectiveness of RugbySmart. Evaluation justifi ed continued investment in the existing program as well as in further areas that warrant investigation. The return on the investment was $7:78 for every ACC $1 invested (Gianotti & Hume, 2007). The results of the RugbySmart program showed a decrease in serious spinal injuries in the scrum (Quarrie et al., 2007), decreases per 100,000 players in moderate to serious injury claims in targeted injury areas (Gianotti et al., 2008), and increases in desired training behaviors in safe scrum, ruck, and tackle at practices/trainings (Gianotti et al., 2008).

Example 3: The SoccerSmart Program—preventing injuries in football (soccer)

Figure 13.3. The RugbySmart DVD used in the workshops The injury problem (Steps 1 and 2) is a key factor in implementing injury prevention in rugby that has resulted in decreases in serious spinal injuries and Based on the initial success of RugbySmart, ACC injury claims in targeted injury areas was keen to implement SportSmart into other Implementing large-scale injury prevention programs 203 sports. Football was targeted as it represented the This is a further hindrance to evaluation and also second largest percentage of sport claims (7.2%) to limits the development of a cost-outcome model ACC. While ACC and New Zealand Football (NZF) to help secure ACC investment. had previously developed some injury prevention 4. Public perceptions. Football is considered a initiatives, they were small and involved using the safer sport than rugby. It does not produce serious generic SportSmart model rather than a football- spinal injuries and parents have been known specifi c one. Attention was also focussed on sec- to remove their children from rugby in favor of ondary/tertiary prevention (e.g., training for the football due to injury risk perception. treatment of soft-tissue injuries). The ACC system could, like in rugby, pinpoint Working toward consensus: identifying the type and nature of football injuries. Initially the the stakeholders focus was all moderate to serious soccer injury To encourage an increased emphasis on injury claims. However, in 2005 the system targeted prevention and to engage NZF, ACC increased its players aged 15–44 years who represent the great- investment in the sport. This provided for NZF est percentage of football moderate to serious to employ a person whose primary responsibility injury claims (85%) with knees (38%) and ankles would be injury prevention, but who would also (19%) being the most predominate injury sites. To be available for other NZF duties. Having a person address these injuries, the SportSmart model was essentially inside NZF devoted to injury preven- adapted for football to provide relevance to the tion gave this topic credibility and emphasis in the target group. Feedback from initial projects with sport. This was essential in developing a coalition NZF had highlighted the need for this specifi city. with NZF. The remaining ACC investment was for In addition, the world governing body for football injury prevention resources, ensuring the injury FIFA’s Medical and Research Committee (F-MARC) prevention person had an established and targeted had developed a program called “The 11” which budget rather than bidding and competing for ACC were keen to see implemented. existing NZF funds. While ACC was prepared to make this investment, it still took NZF 18 months Understanding the facts and belief to formally agree to a coalition. This was more structure refl ective of a busy sport rather than a reluctance to be involved in injury prevention. Key discussion While there was success with the RugbySmart points included compulsory training of coaches concept, football required a completely different and rule changes. NZF was not in the same posi- approach to build a coalition due to the following: tion as NZRU to make injury prevention training 1. Financial considerations: Rugby has an annual compulsory for coaches and the sport also was budget 10–50 times that of other sports with concerned about the expectation to implement the same playing numbers. Investing in the rule changes and the subsequent implications. community aspect of the game on this scale was diffi cult to repeat in other sports. NZF has fewer The SoccerSmart program (Step 3) staff and could not afford to devote the time necessary to develop and implement an injury In 2004, NZF (formally New Zealand Soccer) and prevention program. ACC adapted SportSmart to create SoccerSmart. 2. Non-governed participation: There are different Despite the governing bodies name change, from forms of football that NZF does not control. ACC soccer to football, the SoccerSmart brand was data collection did not distinguish between forms retained because of its market recognition. Football of football (e.g., indoor soccer, 6-a-side, 11-a-side), coaches were identifi ed as a suitable initial target as it is a no-fault system. This impacted on the and SoccerSmart was included in all existing NZF ability to undertake evaluations. coach education courses, as well as a stand-alone 3. Inaccurate playing numbers: NZF does not keep workshop. Resources were created to be included in accurate playing numbers and relies on estimates. each course pack. These included booklets, wallet 204 Chapter 13

Hence a forecast is used on the absolute number of moderate to serious injury claims.

Discussion

The NZ examples show a passive model that can be adapted to other sports and is effective in achieving injury prevention outcomes. In these examples, education plays more of a role than enforcement and engineering of the injury pre- Figure 13.4. The SoccerSmart resources targeting has vention matrix (see chapter 2) since there is no shown a claims reduction against forecast for knee and ankle injuries in 15–44-year-old soccer players ability to enforce rules or make a sport undertake injury prevention by withholding injury coverage. A strong coalition with the national body cards (pocket-sized folded information sheets), and (NZRU, NZF) is crucial for the implementation posters that addressed all 10 SoccerSmart action of an effective sports injury prevention program. points. Resources were designed to be used by While investment and funding is also important, coaches and passed on to players. FIFA’s “The 11” this investment would not have been as effective resources were also included in the SoccerSmart if the national bodies were not supportive. This is course packs (Figure 13.4). SoccerSmart (similar to particularly important for large-scale implementa- RugbySmart) focused on injuries or injury-related tion of injury prevention programs. issues that were more prevalent in the sport of football, as determined from the ACC claims database. These included tackling, physical ﬁ tness, and prematch issues. Special care was also taken with The Canadian Province of Québec the language and phrases used in SoccerSmart, to model ensure suitability for the audience.

Evaluation of SoccerSmart program Injuries resulting from sports and recreational activ- (Step 4) ities are a signiﬁ cant health problem in Québec. The Canadian Community Health Survey of Statistics As with all injury prevention ACC invests in, mod- Canada revealed that in 2003 in Québec, inju- erate to serious injury claims are used for evalua- ries which occurred in a sport and leisure venue tion. Unlike Rugby, NZF could not provide accurate represented 21% of all injuries resulting in limita- playing numbers, nor an accurate estimate of the tion of normal activities or medical consultation, prevalence of indoor soccer. As such, moderate to compared with 35% of injuries at home, and 8% serious injury claims were assessed against a fore- on the road. Moreover, participation in sport and cast, made by ACC, as part of its cost-outcome recreational activities was the leading cause of approach (see Further reading). In 2006/2007, non-intentional injuries in Québec in 2003 (25%), the return on the investment for all soccer mod- before occupational injuries (23%). Of course, sport erate to serious injury claims was $2.41 (Gianotti and recreational activity injuries are not all severe: & Hume, 2007) and there was 2.5% fewer claims there are more deaths on Québec roads than on against forecast for 15–44 year olds in knees and sports ﬁ elds and, generally, road injuries are more ankles. This resulted in ongoing investment in the severe. However, the public health burden of sport SoccerSmart program. However, the actual number and recreational activity injuries is manifest in of football moderate to serious injury claims is their morbidity. A population-based survey done increasing, which is purported to be due to the for the Québec Ministry of Education, Leisure, and anecdotal reports of marked growth of the game. Sport estimates that during the year 2004, 514,000 Implementing large-scale injury prevention programs 205

Québec residents aged between 6 and 74 years con- in the Canadian Hockey Association. In 2004–2005, sulted a health professional to treat a sport and it was estimated that 9%–31% of all Canadian boys recreational activity injury (88/1000 participants). participated in organized leagues. These data clearly show the scale of the sport and In the 1970s, faced with an increase in ice recreational activity injuries problem and the hockey violence and poor performances at the importance of establishing safe environments. international level, Canadian administrators and In 1979, to signifi cantly contribute to the estab- other individuals involved with North American lishment of safe environments, the government of hockey began to question their basic philosophies Québec adopted the Act Respecting Safety in Sports of the game. This awareness sparked increased which created the Québec Sports Safety Board research in ice hockey which was followed, in (Régnier & Goulet, 1995; Government of Québec, some cases, by changes in the rules, particularly 1988). Since 1998, through its mission to “foster at the minor level. One of the major changes was the development of recreation and sport in a safe the abolition of bodychecking for players 12 years and healthy environment and promote an active old and under. Bodychecking is defi ned as an lifestyle for all Québecers,” the Safety Promotion individual defensive tactic designed to legally sepa- Unit of the Québec Ministry of Education, Leisure, rate the puck carrier from the puck by use of phy- and Sport supervised the execution of the Act sical contact. Respecting Safety in Sports. In accordance with this In 1985, to allow Midget age players (15–16 years act, one of the Safety Promotion Unit’s orienta- old) who wanted to play junior hockey to fi nish tions is to “ensure that the safety and physical high school in their home towns, the Canadian security and well-being of participants are pro- Hockey Association decided to raise all age groups vided for during sports and recreation activities.” by 1 year, thus making the Pee Wee category 12–13 With respect to the Act, the Safety Promotion years old. With those age changes, the “no body- Unit is empowered to checking” rule was reconsidered. After a brief dis- 1. Gather, analyze, and disseminate information cussion during their general meeting of 1985, the on sports safety. Canadian Hockey Association adopted a new rule 2. Conduct, or cause others to conduct, research allowing bodychecking for Pee Wee category. on sports safety. In the province of Québec, faced with a contro- 3. Educate the public on safety in relation to the versy on the risk of injuries associated with the practice of sports. new rule, Hockey Québec (the Québec Ice Hockey 4. Prepare safety training methods for persons Federation) asked the Québec Sports Safety Board who work in the sports fi eld. for its opinion on the matter. 5. Give technical assistance to sports federations or unaffi liated sports bodies in preparing safety Understanding the facts and belief regulations. structure 6. Assist any person requesting advice on means to ensure sports safety. Realizing that no hard scientifi c data were avail- Two examples of the application of the Québec able on the effect of bodychecking on the safety of Model are presented in the following example. Pee Wee players, the Québec Sports Safety Board sponsored an appropriate research study (Régnier et al., 1989). Consistent with the fi rst key element Example 4: Bodychecking injuries in mentioned earlier, the multidisciplinary nature of minor ice hockey the research group allowed its members to study the following topics: The injury problem (Steps 1 and 2) 1. The attitudes and beliefs of coaches, parents, and players toward bodychecking. Ice hockey is one of Canada’s most popular winter 2. The morphological and biomedical differences sports, with more than 500,000 registered players among Pee Wee players. 206 Chapter 13

3. The number and types of penalties within is the only province or territory where bodycheck- leagues playing with and without bodychecking. ing is still banned for this age group. In the other 4. The injury rate among Pee Wee leagues playing provinces, there is still controversy about the issue. with and without bodychecking. Government reports and academic studies have iden- 5. The modeling effect of professional hockey. tiﬁ ed some problems related to bodychecking and 6. The training of coaches in the teaching of further educational initiatives have been launched. bodychecking. For example, the Canadian Hockey Association has 7. The effects on participation. been actively providing courses on the appropri- The most inﬂ uential study result relative to pub- ate bodychecking techniques for coaches, players, lic awareness was that Pee Wee players were 12 managers, referees, trainers, and parents. Only a times more likely to suffer a fracture in leagues that few training initiatives have been evaluated and the allowed players to bodycheck. The rate of fracture overall effectiveness of these courses on injury pre- was 1 per 22 games in leagues where bodycheck- vention has not been established. ing was allowed compared to 1 per 263 games in leagues where bodychecking was not allowed. The weight and height difference between players was Evaluation (Step 4) shown to be one of the most important risk fac- It is estimated that in 20 years, this large-scale meas- tors of injury. Morphologic and strength differ- ure prevented 4000 young growing players to suffer ences between the smallest and the largest players from a fracture. Moreover, there is no evidence that competing at the Pee Wee level revealed an aver- the ban of bodychecking at Pee Wee level reduced age weight and height difference of 37.2 kg and the level of competitiveness of Québec players at 31.5 cm, respectively. Furthermore, a 70% differ- national or international levels of competition. ence in the force of impact during bodychecking between a group of small players and larger players was observed. Example 5: Full–face protection to prevent facial injuries for adult ice Working toward consensus: identifying hockey players the stakeholders

With those results, the next step was to convince The injury problem (Steps 1 and 2) the minor ice hockey administrators to ban bodychecking at Pee Wee level. Some factors had major Even if ice hockey is one of the leading contribu- infl uence. The involvement of a well-respected team tors to sports-related injuries in Québec, it proof university researchers in the study was impor- vides the sport and public health communities tant, bringing credibility to the process. Moreover, with an impressive success story of injury preven- the public health network of the province highly tion: the quasi-elimination of eye and facial inju- supported the actions to ban bodychecking at Pee ries through the use of face protectors. Wee level and information campaigns in the media In the mid-1970s, Canadian and US ophthalmol- were launched to infl uence public awareness. ogists documented a signifi cant incidence of seri- Finally, the Minister responsible for the administra- ous eye injuries in ice hockey players. This public tion of the Act Respecting Safety in Sports was lobbied awareness brought together safety specialists, ama- for his support of the proposal. teur ice hockey governing bodies, and sport equipment manufacturers in an attempt to improve The preventive measure (Step 3) available eye and face protective equipment and to increase its routine use in the sport. Based on those results, Hockey Québec decided These efforts led to the adoption of a Canadian to ban bodychecking for all Pee Wee leagues in and a US standard on face protectors for ice Québec (Robidoux & Trudel, 2006). Today, Québec hockey players. The standards led in turn to the Implementing large-scale injury prevention programs 207 adoption of regulations imposing the use of a certifi ed full-face protector for all minor league players (18 years or under) in the United States starting with the 1976 season, and in Canada starting with the 1978 season. However, the large population of adult hockey players remained at risk because full face protection was not required beyond age 18.

Understanding the facts and belief structure

The effect of the use of certifi ed full-face protectors by minor league players have been well documented in Canada and in the United States of America. For instance, no eye injuries have been Figure 13.5. Mandating full-face protection in adult recorded for a player wearing a full-face protec- league Québec ice hockey players has shown a dramatic tor certifi ed by the Canadian Standard Association. decrease in eye injuries and a positive promotional cost/ But the most eloquent demonstration of the effec- health care savings ratio tiveness of full-face protectors was based on reports from Canadian ophthalmologists. In 1974–1975 Working toward consensus: identifying the average age of hockey players suffering from an the stakeholders eye injury in Canada was 14 years. In 1983–1984, 5 years after full-face protectors were imposed on As was the case for the ban of bodychecking at Pee all minor league players by the Canadian Hockey Wee level (Example 4), the regulation imposing the Association, the average age of the victims rose to use of full-face protectors by adult ice hockey play- 24 years (Pashby, 1985). From these results, it was ers was supported by the public health network of determined that the main population at risk of eye the province, and by groups of ophthalmologists injury in hockey had become the thousands of adult in Canada and in the United States of America. recreational hockey players participating in organ- This support signifi cantly enhanced the credibil- ized leagues not subject to the Canadian Hockey ity of the regulation. Social marketing campaigns Association regulation. promoting the use of full-face protectors were also Many studies conducted in Québec between undertaken (Figure 13.5). The Minister responsible 1982 and 1987 confi rmed these conclusions as to for the administration of the Act Respecting Safety the vulnerability of 90,000 adult recreational play- in Sports also had to be convinced. ers not wearing full facial protection. Observations in a representative sample of arenas in Québec The preventive measure (Step 3) revealed that only 25% of these players wore facial protection in 1987 in spite of previous social mar- To signifi cantly reduce the incidence of eyeinju- keting campaigns promoting the voluntary use of ries to adult ice hockey players, the Québec Sports full-face protectors. A major challenge was intro- Safety Board enacted a regulation imposing full- ducing a new piece of equipment to a generation face protectors on all adult ice hockey players par- that had not grown up with it. ticipating in an organized league. It was clear that the use of full-face protectors by adult ice hockey players needed to increase by The evaluation (Step 4) enacting regulation requiring their use. But, before the implementation of such regulation it was The regulation imposing full-face protector had an important to convince the players to comply with immediate and long-lasting effect on the use rate of the regulation. full-face protectors among adult recreational hockey 208 Chapter 13 players in Québec. One year after the adoption of examples in this chapter have shown, they can be the regulation, the use of full face protectors rose successful and positively impact thousands of rec- from 25% to 88% (it was 75% in 2005) with a cor- reational to elite sport participants. In summary, responding reduction in eye injuries. The relatively we revisit the fi ve key elements of a large-scale few eye injuries still reported involve adult players injury prevention program and consider specifi c who choose not to comply with the regulation and lessons learned from our examples that are con- young participants in non-organized situations. sistent with these criteria. Moreover, there is no evidence that the introduction of the full-face protector induced more neck Approach the injury problem at hand injuries or aggressive behaviors from the players. with a multidimensional view An update of a previous study (Régnier et al., 1995) evaluating the economic impact of this Both the New Zealand and Québec models had second regulation from 1988 to 2000 showed a a cost/benefi t ratios that were a specifi c part of cost/savings ratio of 1/13.7; every dollar invested the evaluation process. This information justifi es by the government in the development, promo- existing efforts and creates momentum for future tion, and enforcement of the regulation generated work (e.g., the success of the RugbySmart program 13.70 of savings in health care costs. helped with the development of the SoccerSmart initiative.) Without this information, sport inju- Discussion ries could be considered insignifi cant. Regarding the impact on sport, ice hockey equipment rules From the Québec experience, what would be the changes could have other effects on the game (e.g., answer to the question “Is legislation the answer one could argue that more aggressive play occurs for safety in sport?” We would certainly like to because equipment makes one feel invincible). answer “no,” if for no other reason that it is not These impacts, both positive and negative, need to easy to constrain. In an ideal world, every stake- be identifi ed before implementation and followed holder group (participants, manufacturers of in the evaluation phase. All examples involved equipment, owners of facilities, coaches, instruc- partnerships; a broad group of constituents to tors, teachers, and others) would adopt safe, or agree upon the issue and to have ownership in safer practices on their own. But our past experi- the solution. Pee Wee ice hockey fractures, rugby ence shows that this is not always the case. In fact, head and spinal injuries, or wrestling weight loss the presence of a governmental body such as the practices are examples of targeting a specifi c pop- Québec Sports Safety Board is often essential to ulation and a set of injuries that has the greatest serve as a catalyst and a unifying force to channel possibility of safety success in terms of both injury and co-ordinate interventions. On the other hand, reduction and rehabilitation cost minimization. legislation alone is not the answer. In the Québec Focus specifi cally on these key issues, generate suc- context, the powers defi ned in the Act Respecting cess and acceptance, and then expand as needed. Safety in Sports should be viewed as only one of a number of possible intervention strategies that range from education to coercion. The injury prob- Beliefs confuse the issue: get the facts lems were approached with a multi-dimensional Understanding the existing incentive to cut weight view, well documented facts were gathered to allowed for specifi c effective wrestling rules modi- assess the problem, and coalitions were developed. fi cation to be developed. Injury surveillance was essential in developing the scope of the problem Summary in wrestling and in monitoring effectiveness in the RugbySmart intervention. Existing high-profi le injury prevention efforts (FIFA “11”), position Implementing large-scale injury prevention pro- stands (ACSM Wrestling Weight Loss Guidelines), grams poses many challenges. However as the established models (RugbySmart, mandatory full Implementing large-scale injury prevention programs 209 face protection in youth hockey), and surveillance still human beings; which means that knowledge systems (NCAA ISS, ACC) were important in edu- does not necessarily result in behavior change. cating affected parties of existing medical con- To maximize effectiveness in educational efforts, sensus and provided a credible template. Targeted injury prevention programs need to be engaging, research identifi ed the issues in the Québec body- current, and sport-specifi c, using the right lan- checking issue. Build an evaluation process into guage (less scientifi c, more plain speak) to reach implementation and celebrate success. Follow- the target audience. Associated resources must be up research documented success in the wrestling stimulating and promote the enhanced perform- weight loss, RugbySmart and Québec eye injury ance and enjoyment benefi ts of programs along examples. These publicized successes led to further with injury prevention. These resources need to initiatives, funding and application. Success breeds be designed to make it easier for the coach, refe- success. However, understand that successes in ree or sporting participant to take positive action, large-scale initiative may not match results from thus increasing acceptance of injury prevention. more controlled environments due to the inherent However, backup plans are important. In the complexities associated with educating and evalu- wrestling example, a long-standing position state- ating a much larger, less-controlled population. ment did not alter people’s behavior as much as restricting the use of dehydration devices such as Work toward a consensus: develop saunas and rubber suits. Field sports can minimize coalitions injury risk by well-maintained surfaces, a passive environmental modifi cation. In ice hockey, Even if you are in a position to impose mandatory the mandate of full-face protection and the ban safety measures, make sure you develop strong of bodychecking provided socio-legislative envi- grass-roots support for your intervention and iden- ronmental changes that had a positive impact on tify the key stakeholders (often coaches). While reducing injuries. the NCAA model has the capability to mandate rules, the weight management model was devel- Try to change the perception that more oped with input from a broad base to achieve own- safety brings less fun ership in the solution. In the New Zealand and Québec models, a governmental entity, national One of the strong motivations drawing people to governing body, or designated position clearly recreational activities, in particular to those prac- responsible for the safety of sports and recreational ticed outdoors such as skiing, is the sense of liberty participants with appropriate funding carried two they provide. Safety is often perceived as some- strong messages: (1) injuries resulting from sports thing that will take fun away from these activities. and recreational activities are a signifi cant public Initiatives should promote value and fun as well as health problem and (2) something can be done to safety. For example, safety allows participation, an prevent them from happening. Yet the ability for important selling point for coaches, players, and these entities to gather diverse viewpoints and ulti- the national governing bodies that oversee them. mate consensus enhanced the success of the pre- Coaches, players, and referees should be alerted to vention initiatives. Having high-profi le champions injury prevention successes as soon as possible to (coaches or athletes) promoting the cause also maximize acceptance, increase participation, and helps the development and acceptance process. further reinforce the critical role they play. Once the heavy burden of constant weight management Recognize the limits of information was removed, wrestlers could spend more time campaigns: develop back-up on becoming better technical wrestlers. Emphasizing technological systems topics like nutrition that resonated beyond the athletic fi eld (New Zealand model), also can Public awareness campaigns are important, but have a positive impact on injury prevention on they are not enough. Well-informed people are the fi eld. 210 Chapter 13

areas of intervention resulting in the creation of Conclusion 13 working groups. 4. Participant preparation: Each working group Conceptual advances made in the fi eld of injury held at least one meeting before the summit. The prevention in recent years show that solutions to aim of these meetings was to begin developing sport and recreational injury problems have to be goals with a view to the actions required to reach developed and implemented from an intersecto- those goals. rial perspective. The examples cited in this chap- 5. The Summit: The aim of the summit was to ter emphasize this concept as well as the value of solidify each working group’s action plan. working from an established model or framework. The result was 13 three-year action plans. One We conclude this chapter with an example of a hundred and ten specifi c actions were identifi ed, Summit on Sport Safety, organized and conducted ranging from regulation modifi cations to social by the province of Québec, Canada in the mid- marketing campaigns. Most of the participat- 1990s. The resulting framework established the ing agencies committed themselves to carry out roadmap and the initial collaboration opportuni- the actions falling within their responsibility. ties to drive various injury prevention initiatives A fl exible, easy to use follow-up system has been in the Province for the next decade. It is a model established to track progress and maintain the that can serve as a starting point for future initia- momentum of each group toward honoring their tives in any country. commitment. Beyond the action plans, the most important outcome of the summit was the consolidation of The Québec Sports Safety Board a real network of organizations coming from dif- Summit on Sports Safety ferent fi elds and the public and private sectors. For In order to serve as a catalyst and a unifying force the fi rst time these stakeholders were exchanging to channel and co-ordinate interventions from dis- information and expertise on the common prob- parate groups, each holding part of the solution lem of safety in sport and recreational activities in to this problem, the Québec Sports Safety Board Québec. sponsored the fi rst summit on sport and recreation In 1990, Québec was the province with the low- safety. The summit brought together over 80 asso- est rate of sport and recreational injuries in Canada: ciations and governmental agencies from educa- 67/1000 participants compared with 100/1000 for tion, health, and sports and recreation, both from the rest of the country. In 2003, Québec was still the private and public sectors. The following stages the province with the lowest rate of sport and rec- leading to the summit were. reational injuries in Canada. Although it is impos- 1. Consultation meetings: Close to 100 experts sible to directly link these observations to the and representatives of organizations participated interventions identifi ed in the Sport Summit, they in fi ve meetings. They were asked to precisely strongly suggest trends in the right direction. Our defi ne their fi eld of intervention and their evaluation is that, at the very least, the work of expectations regarding the summit. It was clear the government of Québec and its partners over that participants wanted an “action” oriented the last 29 years has contributed to the creation of event rather than an abstract process. a much safer climate for sports in the province. 2. Sports safety survey: In order to complete the consultation meetings, a questionnaire was posted to 7000 contributors from diverse sectors of intervention. Among other topics, the participants References had to give their opinion on priorities for action over the years to come. Agel, J., Ransome, J., Dick, R.W., Oppliger, R., 3. The program: From the consultation activities, Marshall, S.W. (2007) Descriptive epidemiology of the summit’s management committee selected 13 collegiate men’s wrestling injuries: National Collegiate Implementing large-scale injury prevention programs 211

Athletic Association Injury Surveillance System, pee-wee (12 and 13 years old) division in the province 1988–1989 through 2003–2004. Journal of Athletic of Québec. In C. Castaldi, & E.F. Hoerner (eds.) Safety Training 42, 303–310. in Ice Hockey, pp. 84–103. American Society for Testing American College of Sports Medicine (1996) ACSM and Materials, Philadelphia, PA. position stand on weight loss in wrestlers. Medicine and Régnier, G., Sicard, C., Goulet, C. (1995) Economic Science in Sports and Exercise 28, 9–12. impact of a regulation imposing full-face protectors on Centers for Disease Control (1998) Hypothermia and adult recreational hockey players. International Journal dehydration-related deaths associated with intentional for Consumer Safety 2, 191–207. rapid weight loss in three collegiate wrestlers—North Robidoux, M., Trudel, P. (2006). Hockey Canada and the Carolina, Wisconsin and Michigan, November– bodychecking debate in minor hockey. In December 1997. Morbidity and Mortality Weekly Report D. Whitson & R. Gruneau (eds.) Artifi cial Ice: Hockey, 47(6), 105–108. Culture, and Commerce, pp. 101–122. Broadview Press, Gianotti, S.M., Hume, P.A., Quarrie, K.L. (2008) Peterborough, Ontario. Evaluation of RugbySmart: a rugby union community Scott, J.R., Horswill, C.A., Dick, R.W. (1994) Acute weight injury prevention programme. Journal of Science and gain in collegiate wrestlers following a tournament Medicine in Sport. In press. Government of Québec weigh-in. Medicine and Science in Sports and Exercise 26, (1988) An act respecting safety in sports. Éditeur offi ciel 1181–1185. du Québec, Québec. Horswill, C.A., Scott, J.R., Dick, R.W., Hayes, J. (1994) Infl uence of rapid weight gain after the weigh-in on success in collegiate wrestlers. Medicine and Science in Further reading Sports and Exercise 26, 1290–1294. Pashby, T.J. (1985) Eye injuries in Canadian amateur hockey. Canadian Journal of Ophthalmology 20, 2–4. For information on the NCAA, see www.ncaa.org. Quarrie, K.L., Gianotti, S.M., Hopkins, W.G., Hume, P.A. For information on the NCAA ISS, see www.ncaa.org/ISS. (2007) Effect of nationwide injury prevention For information on the New Zealand Accident programme on serious spinal injuries in New Zealand Compensation Corporation (ACC), see www.acc.co.nz. rugby union: ecological study. British Medical Journal For information on SportSmart, please see www. 334, 1150. sportsmart.org.nz. Régnier, G., Goulet, C. (1995). The Québec Sports For information on ACC RugbySmart, please see www. Safety Board: a governmental agency dedicated to the rugbysmart.co.nz. prevention of sports and recreational injuries. Injury For information on ACC SoccerSmart, please see www. Prevention 1, 141–145. soccersmart.co.nz. Régnier, G., Boileau, R., Marcotte, G., Desharnais, R., For information on the Act Respecting Safety in Larouche, R., Bernard, D., Roy, M.A., Trudel, P., D. Sports, see “Laws and Regulations” in www. Boulanger (1989) Effects of body-checking in the publicationsduQuébec.gouv.qc.ca/accueil.en.html Chapter 14 Planning for major events Michael Turner1 and Jiri Dvorak2

1Lawn Tennis Association and British Horseracing Authority; British Olympic Association and Chief Medical Adviser to Snowsport, UK 2FIFA Medical Assessment and Research Center (F-MARC), Schulthess Clinic, Zurich, Switzerland

the standard injury prevention strategies outlined Introduction in previous chapters because these are primarily aimed at sports governing bodies, coaches, equip- Major events are held all over the world on a regular ment manufacturers, and athletes themselves. basis and providing appropriate medical cover for For example, all major events involving profes- the athletes, support staff, and spectators, as well sional football (soccer) and American Football as initiating injury prevention strategies, should take place in purpose built stadia. Teams travel be a priority for every organizer. with their own medical support staff and there is A major event may involve only two teams com- no possibility of an event Chief Medical Adviser peting in front of 17,000 spectators for less than having any impact on the quality of the pitch, the 2 h on a single day but the variation is infi nite. protective equipment worn by athletes, the train- When planning a major event it is customary to ing technique of players, the falling technique of appoint a Chief Medical Adviser for the event and players, or the rules of the sport. The medical staff it is essential that this individual is familiar with providing support at these events will normally the hazards and risks involved in such an under- have done so on numerous previous occasions and taking. In many instances this will be the same the opportunity to implement injury prevention individual, or team of professionals, and it should strategies at this stage is non-existent. be a priority that medical staff with experience of all the particular challenges are recruited to advise and cover the event. This is especially so in high- What is a “major event”? risk sports where medical staff unfamiliar with the sport may well fi nd that they are ignorant of the environment and equipment in use (motor sport, Global events are often deemed to be “major” as equestrian sports, water sport, winter sports). a result of the huge television audiences that they Depending on how far in advance the Chief attract (the 2006 FIFA World Cup was watched by Medical Adviser is appointed, there should be 26.3 billion people in 214 countries) but this chap- opportunities to implement emergency and injury ter will focus on those events with a large number prevention strategies and to introduce effective risk of spectators in attendance or a large number of management procedures. However, these opportu- participants. nities might not allow for the implementation of The largest number of spectators Sports Injury Prevention, 1st edition. Edited by R. Bahr and L. Engebretsen Published 2009 by Blackwell Publishing For the purpose of this review, we have utilized the ISBN: 9781405162449 fi gures of spectators in attendance only and have

212 Planning for major events 213 identifi ed a selection of global events that attracted Factors to consider an average of 17,000 or more spectators per day. The largest daily crowds are seen at the New York Marathon (2.5 million spectators) and the London The recommendations that follow are the result Marathon (500,000) and the other major events in of a detailed review of selected major interna- this category include the Tour de France cycling tional and national sporting events that occur (434,000/day), Sydney 2000 Olympics (418,000/ around the world. This “basket” of over 40 events day), NASCAR (186,100/day), Kentucky Derby involved 102,432 amateur and professional com- horse racing (156,400/day), Melbourne Cup horse petitors taking part in 9,313 days of competition racing (106,500/day), and Salt Lake 2002 Winter watched on site by over 292 million spectators Games (95,300/day). (this does not include the TV audiences). By comparison, the US professional sports Given the vast variety of these events, the fi rst attracted a large number of spectators over the duty of all medical staff at any sport event is to whole season but only modest numbers attended retrieve and analyze the following basic information: the individual events. The fi gures for 2006 are as • Number of sports—single or multiple follows: • Number of participants—individuals and/or Major League Baseball—94.9 million spectators teams over 2419 games (30,970/event) • Number of support staff—coaches, physical College Football—32.6 million spectators over therapists, medics, sports scientists 709 games (46,039/event) • Number of spectators and VIPs NBA Basketball—21.6 million spectators over • Number of countries involved—national only, 1230 games (17,558/event) international NHL Ice hockey—20.8 million spectators over • Number of venues—single or multiple 1230 games (16,955/event) • Accessibility of venues—static stadium, mobile, The other sports that attract over 10 million spec- global tators include NPB baseball (Japan—19.9 million), • Frequency of event—once only, repeated annu- NFL football (USA—17.3 million), Premier League ally, monthly, weekly soccer (GB—12.8 million), Bundersliga 1 soccer • Number of days medical cover is required (Germany—12.5 million), La Liga soccer (Spain— (including training and preparation days)—1 11.0 million), and the Tour de France cycling (10 day only, weeks, months million). The sports attracting 1–9 million specta- • Special needs of the athletes—wheelchair event, tors are national soccer leagues (Italy, France, Japan), blind competitors the multi-sport, multi-national events (Olympic and • Special challenges of the sport—high speed, Paralympic Games), NASCAR, and the Rugby Union motor vehicles, horses, water, ice, snow World Cup. • Medical services traveling with the individuals or teams—team doctors, physical trainers to The largest number of participants national squads • Medical cover at locations other than the com- Marathons and the multi-sport, multi-national petition venue—hotels, athletes’ village, train- events dominate this group—London marathon ing areas, on-call cover (35,500 participants), New York marathon (17,000), • Need for specifi c medical subspecialties Sydney marathon (13,000), Sydney 2000 • Governing body requirements for medical cover Olympics (10,651—16 days), US College football at events (6,095—709 games), Melbourne Commonwealth • National legislation or guidelines in force Games 2006 (4,500—11 days), Athens Paralympic regarding the medical cover at major events Games 2004 (3,969—12 days), Salt Lake 2002 • National legislation guidelines in force regard- Winter Games (2,399—16 days), and NFL ing temporary licenses of accompanying American football (1,692—256 games). physicians 214 Chapter 14

• Major Incident Medical Management and The coach was locked, and the sun was very hot, Support procedures (for dealing with a catastro- so he sheltered under the coach and fell asleep. The phe on site and access to local hospital facilities) coach driver returned at the end of the afternoon • Accreditation of medical staff—access to venues and reversed the vehicle out of its parking place to and restricted areas prepare for departure. In the process, he ran over • Payments to medical staff—volunteers, travel and killed the sleeping spectator. In both instances, and accommodation expenses, honorarium, the consumption of alcohol was thought to have uniforms, reimbursement of supplies provided played a signifi cant part in the tragic outcome. by the individual. Further, some events representing special chal- This chapter provides an opportunity to explore lenges are explicitly addressed and the specifi c some of the “best practice” issues for medical staff points to be considered are outlined. who have never had the opportunity to supervise or regulate an event of this size and complexity. Although many of the topics under consideration Major event planning tools will not be seen as strictly “injury prevention measures,” the underlining principle is that managing any injury in an effective and rapid fashion may Basic planning well prevent further damage to the individual con- For basic planning purposes, the checklist shown cerned. This will in turn lead to a reduction in the in Table 14.1 provides a summary of all the pre-, rehabilitation time and can be considered as part of during and post-event requirements. the injury prevention—injury mitigation spectrum. It is generally accepted that, following a spinal cord injury, 50% of the resulting disability is Venue medical cover caused by the inept handling of the injured person (lack of immobilization strategy, spinal board, Venue cover is relatively simple, as long as the etc.). It can therefore be seen that having the venue is not spread out too much (Tour de France) appropriate equipment and trained personnel can and the event is not too large (Olympics). Cover signifi cantly impact the outcome of injury and for the participants is often provided by the teams this could reasonably be included in a review of themselves (team doctor and/or physical therapist) injury prevention. In addition, anything that but facilities will need to be provided for them to increases the anxiety or stress levels in an athlete treat the team members throughout the day (see may well lead to a decrease in performance and checklist in Table 14.2): event planning should be aimed at eliminating • Squad treatment room at the competition venue any concerns that relate to medical issues. • Squad treatment room at the training area It is not only the competitors who are at risk in • Squad treatment room at the accommodation this context but also avoidable fatalities can occur area amongst spectators at big sporting events. At the These treatment rooms may be communal areas in Winter Games in Lillehammer (Norway 1994) over events involving multiple sports (track and fi eld). 20,000 people were camped out in tents along the Competition venues need additional attention route of the 50 km cross-country track (overnight because of the large number of spectators (and VIPs) temperatures of –30ºC). One spectator, having left who are in attendance (see checklist in Table 14.3). the tent to fi nd the communal washroom in the middle of the night, was apparently unable to fi nd Provisions for competitors his way back to his tent and was discovered dead in the snow the following morning (Ekeland, 1995). At Competitors may never have visited the venue or the Horseracing Derby (Great Britain 1995) a spec- country prior to the event and when planning a tator who had arrived in a coach felt unwell dur- big event, the organizers must keep the needs of ing the afternoon and returned to the coach to rest. this group at the forefront of all health, welfare, Planning for major events 215

Table 14.1 Checklist basic planning.

Basic planning Pre-event During event

Climate—weather Review statistics for the last 10 years Monitor and publish daily conditions Venues Numbers Monitor daily and adapt Obtain detailed ground plans and carry out an on-site assessment medical support provision Establish opening and closing times for each venue as required Equipment Review the equipment needed at every location where medical support Monitor daily and adapt will be provided medical support provision as required Athletes Numbers and nationalities Monitor injuries daily Date of arrival Time and dates of competitions and training Support staff (incl. Numbers Monitor injuries daily medical staff traveling Date of arrival with the teams or Number of medical staff traveling with each team athletes) Spectators Numbers Monitor injuries daily Time of access to and departure from each venue VIPs Numbers Monitor injuries daily Program of VIP social events Accommodation arrangements The Medical Team Numbers needed Daily meetings Appoint core members and establish recruiting strategy for additional staff Training Ensure that all members of the medical staff have appropriate training (e.g., Monitor during event and Major Incident Medical Management and Support training—see later) arrange additional training if required Specialist services Access to outpatient consultations Monitor access and speed Availability of X-ray, MRI, blood pathology, etc. of reporting Hospital access Identify nearest AϩE unit and open a dialog with senior staff Monitor access and speed of access Central Medical Location and staffi ng (if required) Specialist services on offer to Provide medical service to Service—Polyclinic athletes—e.g., dental surgery all competitors, support staff, and VIPs Communications Establish a method of secure communication between all members of the Monitor daily and adapt medical staff that will protect confi dentiality provision as required Record keeping Establish a unifi ed system for recording and analysis of all injuries and Monitor daily and adapt incidents provision as required Education Prepare briefi ng information for visiting teams Update daily by e-mail, Prepare written Standing Orders for every event and every venue text, or website Insurance Ensure that all medical staff are covered by appropriate insurance Inform Insurers in case of accident or injury (not malpractice insurance) immediately if any accident or injury takes place that involves medical staff Legal issues Ensure that organizers are aware of all Government Legislation concerning Review daily and notify the medical cover at the event and that these are complied with promptly organizing committee (reporting of accidents, fatal incidents, etc.) or relevant authority if required 216 Chapter 14

Table 14.2 Checklist training venue.

Venues for training Pre-event During event

Planning Establish layout and whereabouts of medical rooms Monitor daily and adapt as required and athletes area Ensure that the accreditation issued to medical staff will allow access to all areas

Outdoor venue Inclement weather options Monitor daily and adapt as required

Open—closed Hours that venue will be open daily Publish daily hours that medical facilities will be open and list staff on site

Athletes Numbers expected Record and monitor all injuries or incidents daily

Support staff Number expected Monitor daily and adapt as required (incl. medical staff traveling Provision of medical room for team medical staff with teams or athletes)

Spectators Number expected Monitor daily and adapt as required

Provision of First Aid room

Medical provision Appoint venue speciﬁ c medical team to deal with Monitor daily and adapt as required athletes and spectators

Equipment Review the medical equipment needed at each location Monitor daily and adapt as required

Communication Establish a method of secure communication between Monitor daily and adapt as required all members of the medical staff that will protect conﬁ dentiality of the patients

Record keeping Ensure access to the uniﬁ ed system for recording and Monitor daily and adapt as required analysis of injuries and incidents

Access for emergency Identify and demark areas that must be kept clear for Monitor daily and adapt as required services ambulance access

Major Incident Medical Identify staff who will be responsible for co-ordinating a Monitor daily and adapt as required Management and Support major incident Identify the medical assembly point for major incident (triage area, transport area, etc.) Ensure that all staff get appropriate training

Meetings and education Prepare Standing Orders for each venue Daily debrief for venue medical staff Distribute Standing Orders to all staff in attendance when venue closed

and safety decisions. They will also need to take doctors and physical therapists to enable all par- into account the accommodation and transport ticipants to be treated in a rapid and professional needs of the athletes (Table 14.4). fashion (Table 14.4). • General access medical facility at every competition venue (will normally include a doctor and Teams traveling with their own medical physical therapist on site) support staff • General access medical facility at every training For teams traveling without medical staff, event venue (may only include a single physical thera- organizers should provide adequate numbers of pist on site and a doctor on call) Planning for major events 217

Table 14.3 Checklist competition venue.

Venues for competition Pre-event During event

Planning Establish layout and whereabouts of medical rooms, Monitor daily and adapt as required athletes area, VIP areas Ensure that the accreditation issued to medical staff will allow access to all areas (especially VIP areas) Outdoor venue Inclement weather options Monitor daily and adapt as required Open—closed Hours that venue will be open daily Publish daily hours that medical facilities will be open and list staff on site Athletes Numbers expected Record and monitor injuries and incidents daily Support staff Number expected Monitor daily and adapt as required (incl. medical staff) Provision of medical room for team medical staff Spectators and VIPs Number expected Monitor daily and adapt as required Provision of First Aid room and mobile staff required Medical provision Appoint venue specifi c medical team to deal with Monitor daily and adapt as required athletes and spectators Equipment Review the medical equipment needed at each location Monitor daily and adapt as required Communication Establish a method of secure communication between all Monitor daily and adapt as required members of the medical staff that will protect confi dentiality Record keeping Establish a unifi ed system for recording and analysis of all Monitor daily and adapt as required injuries and incidents that occur during the event Meetings and Invitation for team medical staff to visit venue prior to Daily debrief for venue medical staff education start of competition when venue closed Prepare Standing Orders for each venue

Table 14.4 Checklist competitors.

Competitors Pre-event During event

Arrival Numbers Date of arrival Accommodation—hotel Location and access details or village Identify all security-related issues Training facilities—gym Location Nearest access to medical staff and facilities Training venue Location of changing and training areas Publish Opening times of team Access to medical room, van, or tent medical rooms and how to access Medical staff on site the medical support provided by host (24 hr emergency numbers etc.) Competition venue Location of changing and training areas Access to medical room, van, or tent Medical staff on site Central Medical Hours of opening Service—Polyclinic Rota of medical staff Education Brieﬁ ng literature with details of all medical services, Update daily by e-mail, text, or emergency numbers, and maps (city and venues) website 218 Chapter 14

• General access medical facility at the athlete vil- At any venue where large numbers of peo- lage (will normally include a doctor and physi- ple congregate, the opportunity for the medical cal therapist on site) resources to be totally overwhelmed by a major • On call arrangements to cover “out of hours” incident must be addressed. In an era where terror- periods when other facilities are closed. ist activities occur on an annual basis, we also have instances where accidental explosions (cooking gas) or stand collapse have occurred at sporting events. Medical indemnity and international These events require close co-operation between competition all the emergency services (police, fi re service, Medical staff traveling abroad provides a particular and ambulance service) and the medical team on challenge for organizers because of the medical–legal site. Indeed the emergency services may not be issues surrounding their national qualifi cations. deployed on site for 30 min or more (particularly Within the European Union, medical staff are free to in rural locations) and the only medical support practice in an unrestricted fashion but this does not available will be the event team. apply when traveling to North America or Australia. Major Incident Medical Management and Doctors and therapists may not be insured to prac- Support requires particular training and all medi- tice abroad and will certainly not be entitled to cal staff providing cover at a big event should obtain medicine on prescription in a foreign coun- ensure that they have completed an appropriate try. The organizers need to communicate the need training course. In the United Kingdom, the stand- for a temporary licensing procedure to all visiting ard course takes place over 4 days. physicians in advance. The organizers must therefore As a result of a number of high-profi le disasters at make arrangements for visiting medical staff to have football events in the United Kingdom, the Health access to: and Safety Executive published the Guide to Safety • A pharmacy (or access to a doctor employed by at Sports Grounds (ISBN 978 0 11 702074 0) which the organizing committee to write the necessary covers all aspects of spectator cover (Figure 14.1). prescriptions) These guidelines indicate the minimum level of • A pathology laboratory—blood testing, swabs, medical cover expected for sporting events and a urinalysis summary is included in Table 14.6 to help those • X-ray and imaging facilities practitioners who have no national guidelines to • Specialist opinion follow. • Dental care • Ophthalmology, facio-maxillary surgery, ortho- Very Important People pedic surgery, etc. One way of ensuring that this runs smoothly is to Organizers should be aware that although a few appoint locally established doctors who can serve VIPs are actually former world class athletes, the as mediators for the visiting medical staff and vast majority are not in perfect physical shape. facilitate access to all services. Despite this, they all expect to be treated as if they were potential medalists and when illness Medical cover for the spectators or injury occurs, all other medical resources may need to be diverted. At a single international This often poses the biggest challenge to the event (UEFA Cup Final) VIPs may include Heads organizers and their Chief Medical Adviser. In of State, Royalty, Prime Ministers, and Presidents many cases, nation law is in place that mandates of International Governing Bodies as well as their the minimum standards of medical cover at large partners, children, and guests. A call to attend a events and individual venues may have safety collapsed VIP can severely compromise the normal certifi cates that control capacity and the support spectator medical support provided and divert- services required on site. Table 14.5 provides a ing the athlete medical cover is not an option. checklist covering spectator issues. It may therefore be necessary to recruit additional Planning for major events 219

Table 14.5 Checklist spectators.

Spectators Pre-event During event

Arrival Numbers expected Monitor and update daily Time of access to facility Duration Days of medical cover needed Monitor and update daily Hours of access to medical staff Venue Indoor stadium Monitor and update daily Outdoor stadium Provision for inclement Outdoor urban weather Outdoor rural Medical support Medical room, van, or tent Monitor and update daily Triage points Number and type of medical support needed Equipment required Equipment Review the medical equipment needed at each location Monitor daily and adapt as required Record keeping Ensure access to the unifi ed stem for recording and analysis Monitor daily and adapt as of all injuries and incidents required First Aid support First Aid room, van, or tent Monitor and update daily Number and qualifi cation of First Aid staff needed Equipment required Communication Independent communication network for all medical staff with Monitor and update daily responsibilities for spectators Medical equipment for Access to automated defi brillators on site Monitor and update daily use by non-medics Pharmacy On site Monitor and update daily Nearest to venue Opening times Catering Adequate for the numbers and duration Monitor and update daily Sanitary facilities Adequate for the numbers and duration Monitor and update daily Major incident Ensure that a details major incident plan has been agreed with the Monitor and update daily local police, fi re brigade, and ambulance services Identify staff who will be responsible for co-ordinating a major incident Identify the medical assembly point for major incident (triage area, transport area, etc.) Education and training Clear signage to medical facilities Daily medical staff meeting Standing Orders covering all aspects of spectator medical cover after venue closed Update daily by e-mail, text, or website medical resources solely to cover these individu- Selection and training of medical staff: als for the period that they are in attendance at a the multi-disciplined approach major event. It should also be noted that the secu- Medical support at a major event will not be rity for these individuals is usually managed by the restricted to doctors and physical therapists alone Military or Secret Service and access to the imme- and consideration should be given at an early stage diate area is impossible to achieve without the to the mix of staff required for any particular event necessary accreditation and vetting. This cannot or venue. These individuals may not be required to be achieved at the last minute. Table 14.7 provides be present on site during competition or training a checklist for VIP medical coverage. 220 Chapter 14

and water sports, equestrian sports, and high speed sports (motor racing and motor cycle racing). These are invariably associated with a much higher incidence of signiﬁ cant injury and fatality. Medical support staff at these events must be familiar with the sport concerned, the environment in which it takes place and the type of injury that can be expected. These events require all the basic cover outlined earlier but additional consideration will need to be given (see Table 14.9).

Disability sport and spectators in wheelchairs

Medical support for disability sport is essentially identical to that already outlined apart from the following areas—support staff, transport, and access. However, the support staff/athlete ratio is normally higher for events involving disabled players. Suitable accommodation and transport needs to be available for these individuals to avoid additional stress for the athletes concerned. Wheelchair competitors use one type of chair for competition and another for normal activity. When organizing transport for wheelchair events, it must be possible for competitors to travel with a spare wheelchair to Figure 14.1. Guide to Safety at Sports Grounds (2008) the training or competition site. For events involv- but will normally include a mix of doctors, para- ing wheelchairs, access into and out of transport medics, nurses, physical therapists (physiotherapists, vehicles, accommodation, competition and train- osteopaths, chiropractors, sports therapists, mas- ing venues, changing rooms, medical facilities, and sage therapists), dentists, podiatrists, sports scientists spectator areas must be reviewed and may need to (nutritionists, sports psychologists), and First Aid be adapted (Table 14.10). trained staff. Table 14.8 provides an overview of factors to be considered related to selection and train- Marathon ing of medical staff. The two sporting events with the largest number of competitors in this analysis are both marathons Events requiring special attention and they provide an excellent model for exploring injury prevention strategies. High-risk events (including those The London Marathon has been run continuously taking place at extremes of climate since 1981. Of the 131,000 applicants in the London or high altitude) Marathon only 48,000 (36.6%) are accepted as participants. The age range 18–88 years with a gender A number of events involve additional risk to the bias (69% male/31% female). Of these, 35,557 will competitors because of the nature of the event or actually start the race (74.1% of the accepted appli- the location in which it takes place. These events cation) but over 99% of these will now expect to ﬁ n- provide a much greater challenge to medical sup- ish the race. This ﬁ gure has climbed from 88.7% in port staff and include the outdoor winter sports 1981 as a direct result of the management strategies Planning for major events 221

Table 14.6 Minimum level of medical cover at sport events. Minimum of two First Aid trained staff at every event • At least one First Aid trained person for every 1000 spectators (up to 20,000 spectators) • Over 20,000 spectators—additional one First Aid trained person for every 2000 spectators Each First Aid trained person must be • Over 16 years of age • Have no other duties or responsibilities • Be in post before the fi rst spectator enters the ground • Remain in post until all the spectators have left A designated First Aid room with specifi ed • Size • Fittings and facilities • Design and location • Storage, equipment, and materials • Upkeep and inspection schedule One crowd doctor should be employed when it is anticipated that the crowd will exceed 2000 spectators • The crowd doctor must have suitable training and experience • The whereabouts of the crowd doctor must be known to all First Aid and ambulance staff at all times (communications) • The crowd doctor must be on site before the fi rst spectator enters the ground and remain on site until all the spectators have left • The crowd doctor must have no other duties or responsibilities during this period (e.g., be a team doctor as well) At least one fully equipped accident and emergency ambulance to be on site for all events with an anticipated attendance of over 5000 spectators Crowds 5000 to 25,000 • One fully equipped accident and emergency ambulance (with a paramedic crew) • An ambulance offi cer Crowds of 25,000 to 45,000 • One fully equipped accident and emergency ambulance (with a paramedic crew) • An ambulance offi cer • One major incident equipped vehicle with a paramedic crew • One control unit Crowds of over 45,000 • Two fully equipped accident and emergency ambulance (with a paramedic crews) • An ambulance offi cer • One major incident equipped vehicle with a paramedic crew • One control unit introduced by the organizers of this highly success- the participants will have no special sporting skills ful event. and a signifi cant number may be disabled.

Health questionnaire and medical clearance Education

All applicants are required to complete a health Once accepted, each competitor should be provided questionnaire and to provide a statement from with a detailed education leafl et outlining a simple their own medical practitioner that they are “fi t to training program and providing advice about nutri- run.” The Chief Medical Adviser of the event must tion, fl uid intake, sleep, and rest. be prepared to monitor and manage the information provided on the health questionnaires Climate to assist in providing the necessary medical support for participants. It should also be noted that This should include a review of the different strate- because marathons are now used as fund raising gies that might be needed under different climatic opportunities by many charities, the majority of conditions. In London, experience has shown 222 Chapter 14

Table 14.7 Checklist VIPs.

VIPs Pre-event During event

Arrival Dates of arrival Monitor daily and adapt as required Numbers expected Requirement for interpreting service Accommodation Location and numbers in hotels, staying with friends Provision of medical services at accommodation (house call) throughout the event Attendance at training venues Establish impact on venue medical services Provision of dedicated medical cover if required (see later) Attendance at competition Establish impact on venue medical services Provision of dedicated medical cover if required (see later) Security Establish impact on venue medical services Ensure correct accreditation for medical staff Ensure correct accreditation for medical staff (see later) (see later) Education Brieﬁ ng literature with details of all medical services, emergency numbers and maps (city and venues) Health record Submit health record pass to all participating Safely store sealed records to have them at organizations and ask them to have it completed hand in case of emergency by VIP physicians

that an ideal temperature for a fast event is 10– competitors from the spectators and regulatory 12ºC but the actual temperature range has been arrangements need to be coordinated with event 5.9–21.0ºC over 25 years. Humidity has ranged marshals and police. In London 2006, there were 28–96% and this will have an effect on clothing 1100 marshals at the start, 3050 along the route, and fl uid intake. and 2500 at the fi nish—a total of 6650. Portable toilets need to be available for competitors at the The media start, along the course and at the fi nish (total of 950 in London 2006 race). First Aid stations (39) Education can be greatly enhanced by utilizing and First Aid staff (1200) are required to assist media programs (particularly TV) to follow groups those who get into diffi culties with suitable equip- of novice runners as they prepare for the event. ment (500 stretchers) and transport (68 ambu- This has proven particularly effective in Australia lances) to cater for the more serious cases. and in Great Britain; children’s TV programs are In events of this sort, the needs of the elite ath- regularly used to educate children taking part in letes and those of the amateurs may be completely mini-marathon and “fun run” events. different and provision will need to be made for both groups separately. Venue preparation Other Olympic sports A typical marathon will have water stations every 1.6 km (from the 4.8 km mark) with access All the 29 summer and 7 winter sports run regu- to sports drinks every 8 km (starting at the 8 km lar events on an annual basis. Many of these will mark). Special drinking stations are also set up be classifi ed as big events (World Championships) for the elite runner group where they can place and appropriate medical cover will be needed. The their own prepared drinks—a total of eight along general principles outlined earlier can be applied the 42.2 km course (approximately every 5 km). to all these events, but a number need to be Adequate barriers will be erected to separate the emphasised. Planning for major events 223

Table 14.8 Checklist medical staff.

Medical staff Pre-event During event

Planning How many days Review and update daily How many competitors How many spectators How many venues Location and scope of the Polyclinic

Appointment of staff How many medical staff needed Review and update daily Selection of core staff for venues, Polyclinic and spectator duties Communicate with on-call staff daily to Make provision for extra staff in case of illness or domestic crisis ensure availability at short notice Obtain documentary evidence that all medical staff are suitably qualiﬁ ed, currently registered with their professional organization and have appropriate malpractice insurance

Training Ensure that all staff have appropriate qualiﬁ cations for the duties they have been assigned Arrange appropriate specialist training for some staff (see Major Incident Medical Management and Support—later) Training to use the communication system

Rehearsal Ensure that all staff are familiar with the venues and have had an opportunity to rehearse the extraction of an injured player or spectator Ensure all staff are familiar with and can use the chosen communication system

Arrival and attendance Organize a rota for every member of the medical staff with Review and update daily appropriate rest periods and days off

Venue cover—athletes Number of expected athletes and times of attendance at venue Review and update daily Ensure that all staff are familiar with venue and the sports (events) Monitor all injuries and attendance that will take place in that venue Daily debrief meetings of all venue staff Establish the means of communication at the venue and after event has ﬁ nished ensure that it works in all parts of the venue Daily report to Chief Medical Advisor or Establish if the event will involve disabled competitors— nominated deputy every day wheelchair access required

Venue cover—spectators Number of expected spectators and times of access to venue Review and update daily Ensure that all staff are familiar with the venue and the times that Monitor all injuries and attendance spectators will be on site Daily debrief meetings of all venue staff Establish if the event will involve disabled spectators— after event has ﬁ nished wheelchair access required Daily report to Chief Medical Adviser or nominated deputy every day

Polyclinic cover Number of staff Review and update daily Times of opening Monitor all injuries and attendance Daily debrief meetings of all staff Daily report to Chief Medical Advisor or nominated deputy every day

VIP cover Designated staff to deal with VIP problems throughout event— Review and update daily provide 24 h emergency contact number

Equipment and Establish exact levels of equipment to be located at each venue, Review and update daily communication to be carried by each doctor and ﬁ rst aider, to be available in the Polyclinic Obtain sufﬁ cient walkie-talkies for all medical staff

(Continued) 224 Chapter 14

Table 14.8 (Continued)

Medical staff Pre-event During event

AϩE and transport Number of ambulances and Paramedics needed Review and update daily Location of nearest AϩE department Mechanism of referral to AϩE department Capacity and waiting times of AϩE department Specialist investigations available at this hospital (neurosurgery unit?)

Outpatient services Establish the system for outpatient referral (ophthalmology, Review and update daily urology, gynecology) and how to obtain other investigations (MRI, X-ray, pathology) Establish who will be responsible for payments (the individual athlete or spectator, the organizing committee, National Health Service, Insurance company)

Education Meetings with all medical staff prior to event Daily medical staff meeting after venue Brieﬁ ng literature for all medical staff with maps and contact or clinic closed details for senior staff and emergency services Update daily by e-mail, text, or website

Legislation Ensure that all medical staff are aware of the Government Ensure that all medical staff comply Legislation relating to medical cover at the event promptly with the Government (reporting of accidents, fatal incidents, etc.) Legislation relating to medical cover at the event (reporting of accidents, fatal incidents, etc.)

Insurance Ensure that all medical staff are covered by appropriate insurance in case of accident of injury and have appropriate malpractice insurance (copies of all the current malpractice insurance certiﬁ cates should be kept on ﬁ le by the organizers)

Financial issues Establish number of paid staff and volunteers needed Prepare Review and ensure that agreed and agree budget (signed letter of agreement) payments are made Method and timing of payments to medical staff agreed—to include training and rehearsal days (venue visits)

Standing Orders and equipment held on site, and those carried by the medical staff, must be listed in the Standing Standing Orders must be prepared for every event Orders. and must include the deployment and duties of all medical staff. Prior to every event, these must Briefi ng have been read and understood by all staff on duty at an event. It is strongly advised that all medical Before every event, a detailed briefi ng should staff are required to sign a declaration that they be carried out by senior medical staff. This may have read and understood the Standing Orders include input from the Senior Medical Offi cer on prior to offi ciating at an event. duty, the emergency services (paramedic and ambulance crews), and the First Aid providers. It cannot Supplies and equipment be emphasized how essential this is to the effi cient running of an event. Medical staff must be familiar with all the supplies and equipment that they are carrying or Communications have access to. These must be checked daily and before every event, all items must be in working All staff must have access to a central communi- order and not out of date. A list of all the supplies cation system, they must be trained in using this Planning for major events 225

Table 14.9 Checklist high-risk sports.

Speciﬁ c issues in high-risk Pre-event During event sports

Winter sports (Alpine and Nordic Establish the medical criteria mandated by the Monitor and review the management of skiing, Luge, Skeleton and governing body for medical cover at the event every injury and adapt medical support Bobsleigh) In skiing events these may also include criteria as necessary prohibiting the event from taking place in Halt event if medical support staff are inclement weather (low temperate, high wind required to leave the site and resources speed) are limited Ensure that appropriate rescue equipment and Daily debrief meeting essential personnel are recruited (blood wagons, ski patrols) Ensure that staff who are on site can rapidly reach all parts of the area they are responsible for (that they can ski or have the use of a snowmobile) Ensure that medical staff are familiar with the personal protective equipment used by participants Establish process whereby the event can be delayed or halted if a serious injury occurs Outdoor water sports—including Establish the medical criteria mandated by the Monitor and review the management of multi-sport events with a swim governing body for medical cover at the event every injury and adapt medical support element (sailing, windsurﬁ ng, Ensure that a suitable water-based rescue system is as necessary triathlon, Iron man) in place which enables medical staff to rapidly Halt event if medical support staff are reach all parts of the area they are responsible for required to leave the site and resources Ensure that rescue staff can swim and have suitable are limited safety equipment allocated Daily debrief meeting essential Ensure that medical staff are familiar with the personal protective equipment used by participants Establish a process whereby the event can be delayed or halted if a serious injury occurs Equestrian sports (horse racing, Establish the medical criteria mandated by the Monitor and review the management of 3-day eventing, polo) governing body for medical cover at the event every injury and adapt medical support Ensure that medical staff are familiar with the as necessary personal protective equipment used by Halt event if medical support staff are participants required to leave the site and resources Establish a process whereby the event can be are limited delayed or halted if a serious injury occurs Daily debrief meeting essential Motor sports (Formula 1, motor Establish the medical criteria mandated by the Monitor and review the management of cycle racing, drag racing, governing body for medical cover at the event every injury and adapt medical support NASCAR) Establish a process whereby the event can be as necessary delayed or halted if a serious injury occurs Halt event if medical support staff are required to leave the site and resources are limited Daily debrief meeting essential Events taking place at high Specialist staff (physiologists) must be recruited to Daily distribution of expected weather temperature or altitude advise medical staff and competitors of the conditions particular risks involved in due advance and publish recommendations on adequate preparation Emergency transport— Ensure that additional emergency transport is on Monitor and review daily ambulances and helicopter site or on immediate call to evacuate the expected major trauma cases

(Continued) 226 Chapter 14

Table 14.9 (Continued)

Speciﬁ c issues in high-risk Pre-event During event sports

Communications Highest priority Monitor and review daily All staff must be given suitable equipment and trained to use it All communications equipment must be able to function in inclement weather and across the whole venue site (many kilometers) Training Ensure that all staff are suitably qualifi ed and trained to deal with the injuries that they will encounter. This may include ATLS training in cases where major trauma is expected (equestrian and motor sports) Insurance Ensure that all medical staff are covered by appropriate insurance in case of accident of injury and have appropriate malpractice insurance (copies of all the current malpractice insurance certifi cates should be kept on fi le by the organizers)

Table 14.10 Checklist disability staff.

Disability sport Pre-event During event

Athlete support Ensure that adequate provision is made for additional Obtain daily feedback from athlete support staff staff individuals—accommodation, medical support Review existing arrangements and adapt as necessary Transport Ensure that suitable transport is available at all times Review daily and arrange for defi ciencies to be rectifi ed Access Ensure that access to all areas needed by disabled Review daily and arrange for defi ciencies to be rectifi ed athlete’s is easy and safe

equipment and the equipment must be tested The unexpected event before the event starts. To preserve confi dentiality, it is essential that the network used for medical communication is not shared with other non- It is clearly not possible to predict the unpredict- medical staff. able but the need for fl exibility and having a con- tingency strategy for sudden unforeseen problems Training and Major Incident Medical is essential in the preparation for any major event. Management and Support History has a habit of repeating itself and the need to review similar sporting events that have taken All medical staff must be appropriately trained and place in the past, to plan for the unexpected, and qualifi ed to undertake the duties they have been to pay meticulous attention to detail cannot be allocated. In events that include large crowds, this emphasized enough. may include additional training in major incident On 27th July 1996, a bomb in the Centennial management. Olympic Park in Atlanta killed one spectator and injured 111 others. Security and accreditation In 1998 during the Sydney to Hobart yacht All medical staff must be able to move freely from race, 6 boats sank or had to be abandoned in atro- venue to venue and from area to area (spectators, cious weather, 50 sailors had to be rescued from athletes, training, etc.) within each venue. Careful the water by helicopter and 6 sailors died. Only 2 consideration needs to be given to the levels of fatalities had previously been recorded in the 54 accreditation needed under these circumstances. race history. Planning for major events 227

The Paris-Dakar rally has resulted in at least 48 Conclusion competitor deaths in its 28-year history with an even larger number of spectators’ deaths. Organization of a race that takes place over 10,000 km in some of The challenges presented in planning a major the most inhospitable terrain on the globe is a sig- event are virtually unlimited. However, by care- nifi cant challenge. fully identifying the basic requirements and by Competitors have been assaulted by members of using the specifi c planning tools outlined in this the public (Monica Seles). chapter, the organizers will fi nd that the process Assaults involving spectators are more frequent becomes manageable. A structure can be imposed in soccer and rugby when the national team wins on the event and medical planning can be posi- and the number of assaults increases as the crowd tively channeled to minimize the risk of injury or gets larger, irrespective of the location of the game disaster. (home or away) (Sivarajasingam et al., 2005). Alcohol is frequently associated with disturbances amongst spectators and some events ban the sale or References consumption of alcohol on site. Well-documented sporting disasters have involved stands collaps- ing, stampedes, spectators being crushed, fi res, and Budgett, R., Harries, M., Aldridge, J., Jaques, R., Jennings, D.E. (1997) Lessons learnt at the 1996 locked exits. Events taking place in remote loca- Atlanta Olympic Games. British Journal of Sports tions can easily overwhelm the local emergency Medicine 31, 76. infrastructure, including the local district hospital Dvorak, J., Junge, A., Grimm, K. and Kirkendall, D. which may have very limited specialist cover and (2007) Medical report from the 2006 FIFA World Cup no neurosurgical or burns unit on site. Germany. British Journal of Sports Medicine 41, 578–581. Sub-zero temperatures result in ice formation Ekeland, A. (1995) Proceedings of the 11th International and spectators will be at considerable risk when Congress on Ski Trauma and Skiing Safety, Voss, Norway, April 23–29, 1995. Scandinavian Journal of walking on this surface. At the ski jumping at Medicine and Science in Sports 5, 110–124. Lillehammer 1994 Olympics, fi ne sand was used Guide to Safety at Sports Grounds. 5th Edition (2008) to prepare the paths used by spectators but this ISBN: 978 0 11 702074 0. Health and Safety Executive was rapidly incorporated in a layer of ice as the (HMSO UK). day progressed. This resulted in a large number Guide for Managing Risk in Motor Sport (2007) HB 192- of spectators falling and suffering fractures when 2007. ISBN: 0733781454. Standards Australia, Sydney. returning to the village after the event. Coarse Junge, A., Dvorak, J., Graf-Baumann, T. (2004) Football injuries during FIFA Tournaments and the Olympic gravel was used on subsequent days and the inci- Games, 1998–2001. American Journal of Sports Medicine dence of fractures plummeted. 32, 80–89. Junge, A., Langevoort, G., Pipe, A., Peytavin, A., Wong, F., Mountjoy, M., Beltrami, G., Terrell, R., Holzgraefe, M., Post-event activities Charles, R., Dvorak, J. (2006) Injuries in team sport tournaments during the 2004 Olympic Games. American Journal of Sports Medicine 34, 565–576. Following any major event, an audit should be Sivarajasingam, V., Moore, S., Shepherd, J.P. (2005) undertaken to review the positive and negative expe- Winning, losing and violence. Injury Prevention 11, riences and make recommendations about future 69–70. events of this sort. These results should be published whenever possible to enable other organizers to share your experiences (Budgett et al., 1997; Junge Further reading et al., 2004; Junge et al., 2006; Dvorak et al., 2007). In certain circumstances these may form the basis Major Sports Events: The Guide. (2005) UK of guidelines for the organization of major sporting Sport, London (http://www.uksport.gov. events (Guide for Managing risk in Motor Sport, 2007). uk/pages/major_sports_event_the_guide/ ) Index

abdominal muscles, 91, 96, 105, 106–7, 110, 112 sport-specifi c injury, 30–31 Accident Compensation Corporation (ACC), 198, 200, volleyball, 32 201, 202, 203, 204 injury mechanisms for Achilles tendon, 187, 188, 190, 191, 192, 193 anatomical and biomechanical aspects, 36–7 acromioclavicular joint injury, 135–6, 141 specifi c sports, examples from, 37–8 Act Respecting Safety in Sports, 205, 206, 207, 208 preventive measures for, 38 active versus passive measures, in sports, 15 balance training, 45–7 acute injury, 160, 161 braces, 40, 43–5 versus chronic injury, 97, 105 player skills, improving, 39–40 targeting, 164–5 rule changes, 38–9 acute traumatic injuries/repetitive stress, 120–21, take-home message, 47 153, 164 taping, 40, 41–2 adductor muscles, 91, 94, 95, 99, 105, 107, 109, risk factors for 111, 112 ankle joint laxity, 34–5 age and sport experience, 93–4 ankle ligament sprain, 32 alpine skiing, 5, 10, 14, 17, 49, 50, 146, 153, 182 foot type, foot size, and anatomic alignment of knee ligament injury mechanisms in, 56–7 lower extremity, 34 American Academy of Orthopedic Surgeons, 150 gender, 32–3 American College of Sports Medicine (ACSM), 199 generalized joint laxity, 34–5 American football, 2, 31, 33, 51, 61, 72, 78, 80, 121, height and weight, 33 124, 135, 138, 141, 146, 176, 178, 180, 182, limb dominance, 34 183, 212 muscle strength, 35 American Sports Medicine Institute, 173 play setting, 35 ankle braces, 7, 40 playing position, 35–6 versus tape, 44–5 postural sway, 32, 34 types, 43–4 range of motion, of ankle, 33 ankle injuries, 531 shoe type, 35 epidemiology, 30 take-home message, 36 American football, 31 training and competition program, risk identifi cation basketball, 31 in, 38 gymnastics, 32 ankle joint laxity, 33, 34–5 hiking, 31 ankle ligament sprain, 32, 33, 35 jogging, 31 ankle sleeves, 40, 43 racquet sports, 32 ankle sprain, 30, 31, 32, 33, 40, 45, 72 rugby, 31 injury mechanisms for, 36–8 running, 31 injury prevention matrix for, 39

228 Index 229 anterior cruciate ligament (ACL) injuries, 2, 5, 11, 49, 51, Canadian Province of Québec model, 198, 204–5 55, 60, 66, 67, 69 Canadian Standard Association, 182, 207 and osteoarthritis (OA) prevalence, 4 catastrophic head and spinal cord injury, 176–7 plyometrics, 63 Centennial Olympic Park, 226 prevention program, for team handball, 66–7 Centers for Disease Control and Prevention, 199 risk, 50 cervical orthoses, 146 and single leg balance training, 67–8 chronic disease, 193–4 strength training effects on, 68 chronic elbow injury, 163 targeting participation in, 61–3 chronic overuse injuries, 155 Athens Paralympic Games (2004), 213 chronic versus acute injury, 97, 105 athlete-related crash measures, in sports, 14 closed head injury, see non-penetrating brain injury athletes at risk competition versus training, 78 identifying, 32, 50, 74, 83, 92, 96, 119, 136, 138–9, competition venue, checklist of, 217 155, 177 competitors targeting, 166–7 checklist, 217 athletic hernia, see incipient hernia provisions for, 214, 215 athletics, 91, 92, 198 compression loads, 121 Australian Rules football, 2, 5, 31, 72, 73, 74, 75, concussion and mild traumatic brain injury, 77, 78, 82, 85, 86, 94, 176, 178, 182, 175–6 183, 184 contracting hamstring muscles, force length curve awareness exercises, 126, 127 of, 81 contusions, 2, 140–41, 161, 165 badminton, 31, 32, 143, 187 core instability, 62 balance test, 34 core stability training, 118–19, 147 balance training, 45–7, 68 evidence for, 68 Bankart lesion, 141, 142 crash measures, in sports, 14–15 baseball, 2, 8, 19, 124, 134, 135, 136, 137.138, cycling, 141, 153, 184 146, 153, 154, 155, 157, 166, 168, 176, 182, 183–4, 187 deep spine muscles, 118, 119 and overhead throwers, 168, 170–73 direct impact injuries, 161 basic planning, 214, 215 direct traumatic injuries, 140–41 basketball, 2, 5, 11, 31, 35, 37, 38, 49, 50, 55, 56, 57, 58, disability sport and spectators, in wheelchairs, 220, 154, 187 225–6 basketweave method, 40, 41 disability staff, checklist of, 226 behavioral adaptation, 28 disc degeneration, 116, 117, 118, 120 biomechanical load, 79 diving and acrobatic sports, injury mechanisms body building, 136, 142, 144, 147 in, 123 body mass index (BMI), 33, 51, 94, 193 dominant leg imbalance, 62 bodychecking injuries, in minor ice hockey dynamic instability, 138 evaluation, 206 dynamic neuromuscular analysis (DNA) training facts and belief structure, 205–6 program, 64–5 injury problem, 205 dynamic strength training, 129–31 preventive measures for, 206 see also strength training stakeholders, identifying, 206 dynamic stretching, 195 boxing, 2, 153, 154, 155, 160, 163, 177, 200 dynamometer, 77 British Standard, 183 Bundersliga 1 soccer, 213 eccentric strength training program, 84, 195 using Nordic hamstring lowers, 85 Cam impingement, 111 effectiveness versus effi cacy, 15–16 Canada, 204, 205, 207, 210 elastin, 189 Canadian Community Health Survey, 204 elbow injuries Canadian Hockey Association, 205, 206, 207 epidemiology, 153 230 Index elbow injuries (Continued) equipment-related pre-crash measures, in sports, 14 high demand versus low demand sports, eye injuries, 2, 206, 207, 208 153, 154 high energy injuries, 153–4 face shields, 183 low energy/overuse injuries, 155 facial fractures, 2 injury mechanisms for, 160 fall on an outstretched hand (FOOSH), 153, 161 direct impact injuries, 161 familial tendency and ethnicity, 51 fall on an outstretched hand (FOOSH), 161 fatigue resistance, improving, 83 overuse injuries, 161–3 fi bronectin, 189 throwing sports, injuries in, 163–4 FIFA World Cup (2006), 212 preventive measures for, 164 FIFA’s Medical and Research Committee (F-MARC), 203 acute injuries, targeting, 164–5 fi gure-eight method, 40 athlete at risk, targeting, 166–7 fi gure skating, 117, 153 baseball and overhead throwers, targeting, 168, Finland, 4 170–73 FIS Injury Surveillance System (FIS ISS), 18 early recognition, targeting, 167–8 fl exibility environment, targeting, 165 in hamstring injuries, 77 golf, targeting, 168 in muscle strain injuries, 84–5 overuse injuries, targeting, 165–6 fl exion and extension compression loads, 121–2 take-home message, 173 foot pronation, 52, 54 tennis, targeting, 168, 169–70 football, 2, 8, 124, 135, 176, 177, 180, 187, 202, training, targeting, 166, 166 203, 204 risk factors for, 155, 156 see also soccer external risk factors, identifying, 157–9 football codes, 2, 21, 72, 79, 82, 83 forces, transfer of, 156–7 full-face protection, for ice hockey players mature and masters athletes, 155–6 discussion, 208 racquet sports, risk factors in, 159–60 evaluation, 207–8 repetitive compressive loads, across elbow, 160 facts and belief structure, 207 take-home message, 160 injury problem, 206–7 young athletes and growing bones, 155 preventive measures for, 207 training and competition program, risk stakeholders, identifying, 207 identifi cation in functional performance tests, for sport, 97 skeletal maturity and training, 164 emergency management, 27 gait cycle, stage of, 80–81 England, sport-related fatalities in, 177 generalized joint laxity, 33, 34–5 English Football Association, 2 glenohumeral internal rotational defi cit (GIRD), environment, 165, 182 138, 151 environmental crash measures, in sports, 14 golf, 154, 155, 162, 166, 167, 168 environmental pre-crash measures, in sports, 14 “grapple tackles”, in rugby league, 178 epidemiology, 153 groin injuries of ankle injuries, 30–32 epidemiology, 91–2 of elbow injuries, 153–5 injury mechanisms for of groin injuries, 91–2 acute versus chronic injury, 97, 105 of hamstring injuries, 72–4 mechanism by structure injured, 105–9 of head and cervical spine injuries, 175 training and competition program, risk identifi ca- of knee injuries, 49–50 tion in, 109–10 of low back pain, 114–17 preventive measures for, 110 of shoulder injuries, 134–6 hip ROM, increasing, 111 equestrian, 153, 182, 183, 184, 212, 220, 225 previous groin injury, rehabilitation of, 110–11 equipment, 14, 28–9, 61, 62, 98, 144–5, 146, 181, 182–4, strength training, 111–12 215, 216, 217, 219, 223, 224 take-home message, 112 equipment-related crash measures, in sports, 14–15 risk factors for, 92 Index 231

age and sport experience, 93–4 player position on fi eld, 78 body composition, 94 previous hamstring strain injury, 74–5 gender, 94 race, 77 modifi able intrinsic risk factors, 94–5 take-home message, 78–9 muscle strength and function, 95–6 training and competition programs, risk non-modifi able intrinsic risk factors, 93 identifi cation in, 81–2 sport specifi city, 94 hamstring muscle strain injury, 74–5 take-home message, 96–7, 98–104 MRI investigations, 76 training background, 95 prevention, 89 ground hardness, 182 rehabilitation program, 86, 87 Guide to Safety at Sports Grounds, 218, 220 risk, 72 gymnastics, 31, 32, 50, 114, 115, 117, 120, 121, 123, 124, size, 76–7 153, 154, 155, 160, 162, 163, 165 hamstring muscle strength, 75, 77, 82, 83 hamstring/quadriceps strength ratio, 77, 89 hamstring injuries, 5, 72, 95 handball, 1, 2, 5, 11, 31, 37, 49, 50, 51, 66, 187 epidemiology, 72 head and cervical spine injuries diagnosis, 73 epidemiology, 175 time loss, 73–4 injury mechanisms for, 177–8 injury mechanism for head injury, biomechanics of, 178–9 excessive biomechanical load, 79 spinal cord injury, biomechanics of, 179–80 gait cycle, stage of, 80–81 pathophysiology, 175 hamstring muscle injured, 80 catastrophic head and spinal cord injury, musculotendinous junction, 80 176–7 principles, 79 concussion and mild traumatic brain injury, reduced load tolerance, 79–80 175–6 take-home message, 81 preventive measures for, 180 preventive measures for, 82 administrative controls, 180–81 athletes at-risk, identifying, 83 environment, 182 fatigue resistance, improving, 83 equipment, 183–4 fl exibility, 84–5 neck muscle strengthening, 184 hamstring injuries, rehabilitation of, 85–6, personal protective equipment, 182–3 87, 88 preparticipation screening for, 181–2 hamstring muscle injury prevention, current secondary injury prevention, 184 trends in, 89 training, 182 injury management, current trends in, 86–8 risk factors for, 177 sport, changing, 88–9 take-home message, 184–5 strengthening, 83–4 head-fi rst and diveback sliding techniques, 146 take-home message, 89–90 head injuries, 2, 4, 5, 8, 17, 27, 176, 182, 183 thermal pants, 88 biomechanics, 178–9 training specifi city, improving, 83 in soccer, 12, 180 warm-up, 88 heavy loads, 121, 124, 147, 153 with resultant posterior thigh bruising, 73 helmets, 15, 180, 182–3, 184 risk factors for, 74 hierarchy of controls, 20 competition versus training, 78 high demand versus low demand sports, 153, 154 fl exibility, 77 high energy injuries, 153–4 hamstring muscle strain injury, size of, 76–7 high intensity and strength training, 195 hamstring muscle strength, 77 high-risk events, 220 hamstring/quadriceps strength ratio, 77 high-risk sports, checklist of, 225–6 insuffi cient warm-up, 78 hiking, 31 level of competition play, 78 hip and knee control, 67 muscle fatigue, 78 hip muscles, stretching program for, 98–9 older athletes, 75 hip ROM, 111 232 Index hyperlordosis, 119 injury prevention matrix, 14 ice hockey, 2, 15, 49, 50, 91, 92, 93, 95, 105, 110, 115, for ankle sprains, 39 124, 135, 141, 154, 176, 178, 180, 182, 183, 184, applied to ACL injury prevention, 62 205, 206, 209 applied to shoulder injury prevention, 146 applied to sporting head and neck injury prevention, iliopsoas muscle, 91, 105–6, 107, 112 181 incipient hernia, 91, 106 for elbow injuries, 165 inciting event, 10, 12 for groin injuries, 98 indirect traumatic injuries, 141–3 for hamstring strains, 83 injury injury prevention program, developing and managing, causation, 10 17 causes, 9 equipment and facilities etiology, 9–11 behavioral adaptation, 28 injury mechanism, 11–14 inspection and maintenance, 29 modifi able and non-modifi able risk factors, 11 international and national standards for, 28 risk factors, 9, 10 training, 29 classifi cation, 8 implementing, 15–16 defi nition, 8 medical staff, roles of, 20 exposure, 9 emergency management requirements, loading patterns, associated with, 121–3 identifi cation of, 27 recurrence, 9 injury management and prevention, education severity, 8–9 regarding, 26–7 surveillance, 8 injury risk management, coordination of, 27–8 injury management injury surveillance program, developing, 21–2 current trends in, 86–8 monitoring, 25–6 and prevention, 26–7 preseason screening, 24–5 injury mechanisms, 10, 11–14, 140 return to play, following injury, 26 for ankle sprains, 36–8 season analysis, 22–4 categories, 13 risk management, principles of, 17 for elbow injuries, 160–64 agreement, on injury prevention, 20 general, 177–8 risk control, 19–20 for groin injuries, 97, 105–10 risk identifi cation and assessment, 18–19 for hamstring injuries, 79–81 injury prevention protocol, for tennis, 169–70 head injury, biomechanics of, 178–9 injury prevention research for knee injuries, 56–60 model, 8 for low back pain, 120–24 sequence, 7–8 for shoulder injuries, 140–45 steps, 198 spinal cord injury, biomechanics of, 179–80 injury prevention strategies, 146 for tendon overuse injuries, 191–2 injury problem, analyzing, 197, 208 injury prevention, in sport, 1, 19 injury risk management, coordination of, 27–8 agreement on, 20 injury risks, 17, 156–7 evidence base for, 3–4 injury surveillance program, developing, 21–2 future, 5 Injury Surveillance System (ISS), 198 importance, 1–3 inspection and maintenance, of equipment and sports participation, 4–5 facilities, 29 systematic approach, 7 intercondylar notch width, 53 injury, causes of, 9–14 intermediate spine muscles, 118 injury prevention programs, implementing, 15–16 “internal impingement”, 137, 138 injury prevention research, sequence of, 7–8 internal tibial rotation, 60 injury surveillance, 8–9 international and national standards, for equipment intervention methods and programs, and facilities, 28 developing, 14–15 International Skiing Federation (FIS), 18, 29 Index 233 interspinous ligament sprains, 116 patella tendon-tibia shaft angle, 54–5 interval rehabilitation program, 167 take-home message, 55–6 interval throwing program, 166 tibial plateau slope, 54–5 intervention methods and programs, developing, 14 training and competition program, risk identifi cation active versus passive measures, 15 in, 60 crash measures, 14–15 knee ligament injury mechanisms, in alpine post-crash measures, 15 skiing, 56–7 pre-crash measures, 14 IOC Medical Commission, 1 La Liga soccer, 213 lacerations, 2 javelin, 154, 155, 163, 166 lacrosse, 35, 135, 154, 155, 165 jogging, 31 laminin, 189 joint laxity, and ligament material properties, 54 large-scale injury prevention programs, implementing, 197 Kentucky Derby horse racing, 213 American National Collegiate Athletic Association knee injuries, 49 model, 198 epidemiology, 49–50 back-up technological systems, developing, 198, 209 injury mechanisms for bodychecking injuries, in minor ice hockey internal tibial rotation, 60 evaluation, 206 knee ligament injury mechanisms, in alpine skiing, facts and belief structure, 205–6 56–7 injury problem, 205 non-contact ACL injury situations, description of, preventive measures for, 206 56, 57, 58 stakeholders, identifying, 206 quadriceps-induced anterior tibial drawer, Canadian Province of Québec model, 204–5 59–60 coalitions, developing, 198, 209 take-home message, 60 facts on injury problem, 168, 208–9 valgus loading, 58–9 full-face protection, to prevent facial injuries preventive measures for, 60 discussion, 208 core stability training, evidence for, 68 evaluation, 207–8 movement biomechanics, technique and education facts and belief structure, 207 components, 63–7 injury problem, 206–7 plyometrics, 63 preventive measures for, 207 safety equipment, 61 stakeholders, identifying, 207 single leg balancing component and ACL injury risk, injury problem, analyzing, 197, 208 67–8 NCAA Wrestling Weight Management Program, 199 strength training effects, on ACL injury risk, 68 components, 199–200 take-home message, 69 discussion, 200 targeting participation, in ACL injury interventions, evaluation, 200 61–3 facts and belief structure, 199 training dosage, 68–9 problem, 199 risk factors for, 50, 51–2 stakeholders, identifying, 199 age, 51 New Zealand model, 200–201 anatomical factors, 51, 53–4 Québec Sports Safety Board summit, on sports safety, body composition, 51 210 external risk factors, 51 RugbySmart program familial tendency and ethnicity, 51 evaluation, 202 foot pronation, 54 facts and belief structure, 201 hormonal factors, 54 injury problem, 201 internal risk factors, 51 stakeholders, identifying, 201–2 ligament material properties and joint laxity, 54 safety, 198, 209 movement patterns, 55 SoccerSmart program, 202 neuromuscular measures, 55 evaluation, 204 234 Index large-scale injury prevention (Continued) lumbar spine, 115, 116, 117, 122, 124 facts and belief structure, 203 muscles, 118 injury problem, 202–3 stakeholders, identifying, 203 magnetic resonance tomography (MRI), 54, 73, 76, 115, lateral ankle ligaments, 30, 36 116, 117, 121, 123 mechanism, for injury, 38 major events, planning for, 212 ligament material properties and joint laxity, 54 events requiring special attention limb dominance, 33, 34 disability sport and spectators in wheelchairs, 220, “Little Leaguers Shoulder”, 137 225–6 load tolerance, of muscles, 79–80, 81 high-risk events, 220 loading patterns, associated with injury, 121–3 marathon, 220–22 compression loads, 121 Olympic sports, 222, 224, 226 fl exion and extension compression loads, 121–2 factors, 213–14 rotation compression loads, 122–3 participants, 213 London Marathon, 213, 220 post-event activities, 227 lordotic lumbar back, see hyperlordosis spectators, 212–13 low and high load tests, for assessment of scapular tools stability, 140 basic planning, 214, 215 low back pain, 114 medical cover, for spectators, 218, 219, 221 anatomy and function, of spine medical indemnity and international competition, core stability/neuromuscular control, 118–19 218 development, 117–18 provisions, for competitors, 214, 215, 217 lumbar spine, muscles of, 118 selection and training, of medical staff, 219–20, 223–4 epidemiology teams traveling with medical staff, 216–18 adult athletes, low back pain in, 115–16 venue medical cover, 214, 216, 217 increased training levels, 114 very important people (VIP), 218–19, 222 radiological abnormalities, in spine of athletes, unexpected event, 226–7 116–17 Major Incident Medical Management and Support, 218 spondylolysis, 117 Major League Baseball, 213 young athletes, low back pain in, 114–15 marathon, 220–22 injury mechanisms for climate, 221–2 acute trauma or repetitive stress, 120–21 education, 221 in diving and acrobatic sports, 123 health questionnaire and medical clearance, 221 loading patterns, associated with injury, media, 222 121–3 venue preparation, 222 for spine injuries, 123–4 mechanics of sports, 138 prevention methods, 124 medial collateral ligament (MCL) injuries, 49, 58, 61 principles, 125–31 medial elbow ligaments, anatomic drawing of, 157 secondary prevention, 132 medical attention injuries, 8 take-home message, 132 medical indemnity, and international competition, 218 risk factors for medical staff age, 120 checklist, 223–4 hyperlordosis or excessive curvature, of lower roles, 20 spine, 119 emergency management requirements, identifi ca- improper technique, 119 tion of, 27 posture, 119 injury management and prevention, education previous injury, 120 regarding, 26–7 sex, 120 injury risk management, coordination of, 27–8 training and competition program, risk identifi cation, injury surveillance program, developing, 21–2 124 monitoring, 25–6 low demand versus high demand sports, 153, 154 preseason screening, 24–5 low energy/overuse injuries, 155 return to play, following injury, 26 Index 235

season analysis, 22–4 non-rigid ankle braces, 40 selection and training, 219–20 Nordic hamstring lowers, 84, 85 teams traveling with, 216–18 nordic skiing, 153 Melbourne Commonwealth Games (2006), 213 notch width index, 54 Melbourne Cup horse racing, 213 NPB baseball, 213 modifi able intrinsic risk factors, 11, 92, 94–5 mouthguards, 183 Olympic Games, 1, 2, 60 movement biomechanics, technique and education com- Olympic sports, 49, 50, 56, 91, 222, 224, 226 ponents, 63–7 briefi ng, 224 movement patterns, 55 communications, 224, 225 multi-national events, 213 security and accreditation, 226 muscle fatigue, 75, 78 standing orders, 224 muscle strains, 116 supplies and equipment, 224 muscle strength, 33, 35, 53 training and major incident medical management and and fl exibility, 194 support, 226 and function, 95–6 Olympic summer program, 2 musculoskeletal preparticipation examination, 96, 97 Olympic winter sports, 49 optimal throwing or serving technique, 158 NASCAR, 213 osteitis pubis, 91, 94, 95 National Collegiate Athletic Association (NCAA) model, overhead athletes, 137, 167 18, 198 overuse injuries, 143–4, 161–3, 164 National Federation of State High School Associations preventing, 147–50 (NFHS), 200 targeting, 165–6 National Football League, 135 National Hockey League, 18, 92, 93, 95 padded headgear, 182, 183, 184 National Soccer Leagues, 213 Panjabi’s model, of stability, 118 National Wrestling Coaches Association, 199 Paris-Dakar rally, 227 NBA basketball, 213 passive stability, 137–8 NCAA Committee on Competitive Safeguards and passive versus active measures, in sports, 15 Medical Aspects of Sports, 18 patellar tendon, 54–5, 187, 190, 192 NCAA Sport Rules Committees, 18 patella tendon-tibia shaft angle (PTTSA), 52, 54–5 NCAA Wrestling Weight Management Program, 199 personal protective equipment, 182–3 components, 199–200 “phantom foot mechanism”, 56, 58 discussion, 200 Pincer impingement, 111 evaluation, 200 pitch count guidelines, in youth baseball, 173 facts and belief structure, 199 plyometrics, 63, 69 problem, 199 post-crash measures, in sports, 15, 184 stakeholders, identifying, 199 post-traumatic osteoarthritis, 2 neck muscle strengthening, 184 postural sway, 32, 33 net-line rule, 39 pre-crash measures, in sports, 14 neuromuscular control training, 118–19, 126, 128–9 Premier League soccer, 213 neuromuscular training, 45, 60–61, 63, 69 preparticipation examinations, see preseason New York Marathon, 213 examinations New Zealand model, 200–201 preseason examinations, 24–5 New Zealand Rugby Union (NZRU), 201, 202, 203, 204 for head and neck injury, 181–2 NFL American football, 213 pre-season training programs, 82, 95 NHL ice hockey, 213 preventive measures NOCSAE standards, 182 for ankle injuries, 38–47 non-contact ACL injury situations, description of, 56, for elbow injuries, 164–73 57, 58 for groin injury, 110–12 non-modifi able intrinsic risk factors, 11, 92, 93 for hamstring injuries, 82–90 non-penetrating brain injury, 175 for head and cervical spine injuries, 180–84 236 Index preventive measures (Continued) rugby, 2, 4, 31, 72, 73, 78, 80, 176, 177, 178, 182, 183, for knee injuries, 60–69 184, 203, 204, 227 for low back pain, 124–32 rugby scrum, 180 for shoulder injuries, 145–51 Rugby Union football, 176, 183 for tendon overuse injuries, 194–5 Rugby World Cup, 180, 213 preventive training, principles of RugbySmart program, 201 awareness exercises, 126, 127 evaluation, 202 dynamic strength training, 129–31 facts and belief structure, 201 stability training/neuromuscular control, 126, 128–9 injury problem, 201 previous groin injury, rehabilitation of, 110–11 stakeholders, identifying, 201–2 primary injury prevention, 7, 175 running, 31, 80, 105, 124, 182, 187 proprioceptive training program, 45, 46 protective equipment, 144–5 safety equipment, 61 proteoglycans, 188–9 Salt Lake (2002) Winter Games, 213 PubMed search, 3 season analysis, 22–4 secondary impingement, mechanism of, 143, 144 Q-angle, 53 secondary injury prevention, 7, 132, 175, 184 quadriceps dominance, 62 semi-rigid braces, 44 quadriceps tendon, 188 shoe–surface interaction, 51 quadriceps-induced anterior tibial drawer, 59–60 shot put, 153 qualitative risk matrix, in community rugby, 19 shoulder injuries, 134 Québec Sports Safety Board summit, on sports safety, 210 epidemiology, 134–6 race, 52, 75, 77 injury mechanisms for, 140 racquet sports, 32, 162 direct traumatic injuries, 140–41 risk factors in, 159–60 indirect traumatic injuries, 141–3 racquetball, 32, 155, 165 overuse injuries, 143–4 randomized controlled trials (RCTs), 3, 4, 8, 112, pain, 144 182, 183 protective equipment, 144–5 repetitive compressive loads, 160, 162 preventive measures for, 145 repetitive overuse injuries, 155, 159 getting back after shoulder injury, 151 risk assessment, 17, 18–19 overuse injuries, preventing, 147–50 risk compensation, see behavioral adaptation strength training, 150–51 risk control, 17–18, 19–20 take-home message, 151 risk factors, 9, 10 traumatic injury, preventing, 146–7 for ankle injuries, 32–6 risk factors for, 136 for elbow injuries, 155–60 age, 136–7 for groin injury, 92–7, 98–104 anatomical factors, 137 for hamstring injuries, 74–9 athletes at risk, identifying, 138–9 for head and cervical spine injuries, 177 dynamic instability, 138 for knee injuries, 50–56 external factors, 138 for low back pain, 119–20 gender, 137 for shoulder injuries, 136–40 mechanics of sports, 138 for tendon overuse injuries, 192–4 passive stability, 137–8 risk identifi cation, 18 take-home message, 139–40 risk management, 21 training and competition program, risk identifi cation principles, 17 in, 145 agreement, on injury prevention, 20 side-arm motion of delivery, 159 risk control, 19–20 single leg balance training, and ACL injury risk, risk identifi cation and assessment, 18–19 67–8 risk of concussion, in elite sports, 176 single load, 121 rotation compression loads, 122–3 skeletal maturity and training, 164 rowing, 115, 124, 200 SLAP lesion, 137, 141, 142 Index 237 snowboarding, 5, 15, 49, 146, 160, 176, 182, 184 Sydney to Hobart yacht race (1998), 226 soccer, 1, 5, 8, 11, 12, 30–31, 35, 37, 39, 49, 50, 55, 72, systematic approach, to sport injury prevention, 7 73, 74, 75, 78, 82, 91, 92, 93, 115, 117, 124, 154, injury 176, 177, 180, 183, 184, 227 causes, 9–14 see also football classifi cation, 8 SoccerSmart program, 202 defi nition, 8 evaluation, 204 exposure, 9 facts and belief structure, 203 recurrence, 9 injury problem, 202–3 severity, 8–9 stakeholders, identifying, 203 surveillance, 8 softball, 19, 134, 135, 146, 151, 154, 155, 156, 159, 166, injury prevention programs, implementing, 15–16 182 injury prevention research, sequence of, 7–8 specifi c sports, 37–8 intervention methods and programs, developing, 14 spectators, 212–13 active versus passive measures, 15 checklist, 219 crash measures, 14–15 medical cover for, 218, 219, 221 post-crash measures, 15 speed skating, 91, 92, 153 pre-crash measures, 14 spinal cord injury biomechanics, 179 taping, 40 rugby scrum, 180 versus braces, 44–5 mechanisms for, 123–4, 179 methods for, 41–2 spine team setting, 17 anatomy and function 10-point action plan, 201, 202 core stability/neuromuscular control, 118–19 10-step rehabilitation program, 26 development, 117–18 tenascin-C, 193 lumbar spine, muscles of, 118 tendinopathy, 187–8, 192, 193 radiological abnormalities in, 116–17 tendon spondyloarthropathy, 193–4 architecture, 189 spondylolysis, 116, 117, 119, 120 mechanics and strength, 190 sport-specifi c injury, 30–31 adaptation to loading, 190–91 sport specifi city, 94, 109–10 pathology, 191, 192 sports concussion, 175–6 structure, 188 intrinsic and extrinsic risk factors in, 177 tendon matrix proteins, 188–9 sports hernia, see incipient hernia tendon overuse injuries, 187 sports participation, from public health perspective, 4–5 mechanics and strength, of tendon, 190 SportSmart model, 201, 202, 203 tendon adaptation, to loading, 190–91 squash, 32 tendon pathology, 191, 192 stability, 119 mechanism, 191–2 stability exercise program, 128–9 preventive measures for standard neuro-musculoskeletal examination, 96 adaptation to loading, 194 standard shoulder training program, 147 eccentric training, 195 static stretching, 195 high intensity and strength training, 195 sternoclavicular joint injury, 141 stretching, 195 strength training, 111–12, 150–51 take-home message, 195 effects on ACL injury risk, 68 training load, adjusting, 195 and high intensity, 195 risk factors for stress strain curve, 190 age, 192–3 superfi cial spine muscles, 118, 119 body composition, 193 suprascapular nerve injury, 137 chronic disease, 193–4 supraspinatus tendon, 144, 187 genes, 193 swimming, 91, 92, 134–5, 137, 144 muscle strength and fl exibility, 194 Sydney 2000 Olympics, 213 range of joint movement, 193 238 Index tendon overuse injuries (Continued) knee injuries, 60 sex, 193 low back pain, 124 take-home message, 194 shoulder injuries, 145 tendon structure, 188 traumatic injury, prevention of, 146–7 architecture, of tendon, 189 trunk/pelvis instability, see core instability tendon matrix proteins, 188–9 type I collagen fi brils, bundles of, 188 tennis, 32, 115, 117, 120, 123, 124, 134, 135, 137, 145, type II muscle fi bers, 75 154, 155, 156, 157, 159, 160, 166, 167, 168, type V collagen, 193 169–70 tertiary injury prevention, 7, 203 unexpected event, 226–7 “The 11” program, 203, 204 United Kingdom, 176, 183, 218 thrower’s 10 exercise prevention program, 170–72 United States, 1, 31, 134, 175, 176, 183, 198, 200, 207 throwing sports, injuries in, 163–4 US Catastrophic Injury Registry, 176 tibial plateau slope, 54–5 US College football, 213 timeloss injuries, 8 USA baseball, 173 torso muscles, exercises for restoring recruitment of, USA Wrestling, 199 99–104 Tour de France cycling, 213 valgus loading, 58–9, 155, 157, 163 training, 29, 126, 182, 215, 223, 226 valgus-extension overload, 162, 163, 168 background, 95 van Mechelen’s approach, 7, 14 versus competition, 78 venue medical cover, 214, 216, 217 dosage, 68–9 very important people (VIPs), 215, 217, 218–19, 222 levels, 114 volleyball, 2, 5, 30, 31, 32, 33, 35, 37, 38, 39, 50, 55, 58, load, 195 135, 154, 187 of medical staff, 219–20 volleyball-specifi c proprioceptive program, 46–7 program, 148–50 and skeletal maturity, 164 Wales, sport-related fatalities in, 177 specifi city, 83 water polo, 2, 124, 135, 137 venue, 216 weight lifting, 114, 115, 117, 124, 136, 137, 138, 143, training and competition program 144, 153, 154, 155, 160, 162, 163, 167 review, 22–4 World Cup, 18, 181 risk identifi cation in wrestling, 50, 114, 115, 117, 121, 123, 124, 135, 153, ankle injuries, 38 154, 166, 177, 199, 200, 208, 209 elbow injuries, 164 wrist injuries, 5 groin injuries, 109–10 hamstring injuries, 81–2 X-rays, 115, 116, 123