A Review Paper

Epidemiology, Treatment, and Prevention of Lumbar Spine Injuries in Major League Baseball Players

Christopher L. Camp, MD, Matthew S. Conti, BS, Terrance Sgroi, PT, Frank P. Cammisa, MD, and Joshua S. Dines, MD

resulted in a mean of 1016 disabled list days per Abstract season from 1995 to 1999.1 Similarly, core and In recent years, increased attention has back injuries were responsible for 359 disabled list been paid to injuries occurring in Major designations from 2002 to 2008. This represented League Baseball (MLB) players. Although 11.7% of all injuries resulting in time out of play most of the current orthopedic literature during that time span.2 During that time, regarding baseball injuries pertains to the prevalence ranked 6th highest of all possible body shoulder and elbow, lumbar spine injuries regions (out of 17), and both position players and are another common reason for time pitchers were similarly affected (7.8% and 7.4% out of play. Back and core injuries may of all injuries, respectively).2 These injuries often represent as many as 12% of all injuries result in a significant time out of play and can have a that result in time out of play from MLB. tremendous impact on player This high rate of injury is likely related health. A healthy, stable, and to the critical role that the spine plays in well-functioning lumbar spine every major baseball-related movement. is a prerequisite for nearly all Linking the upper extremities to the hips baseball-related activities, and lower extremities, a healthy, strong, including pitching, throw- and stable spine and core is a prerequisite ing, batting, and running. for performance in all levels of baseball. Accordingly, even minor It has been well documented that base- lumbar spine injuries may ball players with poor spinal control and profoundly influence baseball stabilization are at increased risk for future performance. Despite this, injury. Common etiologies of lumbar inju- less is currently known about ries include stress fractures, muscle injury, the true epidemiology and annular tears with or without disc hernia- impact of back injuries in pro- tion, facet joint pain, sacroiliac joint pain, fessional baseball compared and stenosis. This review discusses the to other professional sporting epidemiology of spinal injuries in baseball. organizations.3 Special attention is paid to the role of the The most common causes spine in baseball-related activities, com- of low and injury in mon injuries, tips for making the correct elite baseball players include diagnosis, treatment options, outcomes, muscle strains, stress rehabilitation, and injury prevention. fractures (spondylolysis), an- nular tears, disc herniation, stenosis, transverse process or the last 20 years, injuries resulting in time out fractures, facetogenic pain, and sacroiliac (SI) joint of play have been on the rise in Major League arthropathy.4-8 These injuries present in a variety of Baseball (MLB), and those affecting the back ways with varying symptomatology. Accordingly, F 1,2 are no exception. In the first comprehensive a thorough understanding and comprehensive ap- report on injuries in MLB players, back injuries proach to the diagnosis and treatment of these in-

Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article.

www.amjorthopedics.com March/April 2016 The American Journal of Orthopedics ® 137 Epidemiology, Treatment, and Prevention of Lumbar Spine Injuries in MLB Players

juries is necessary. The purpose of this article is to work diligently to stabilize the entire kinetic chain. discuss the current state of lumbar spine injuries in Of all the trunk muscles (paraspinal, rectus abdom- professional baseball players. Specifically, we will inis, obliques, and glutei), the lumbar paraspinal discuss the critical role of the spine in baseball ac- muscles often work the hardest during the pitching tivities, common causes of injury, tips for making motion, demonstrating activity increases ranging the diagnosis, treatment options, outcomes, and from 100% to 400%.10 Accordingly, it is not uncom- injury prevention and rehabilitation strategies. mon for pitchers to develop SI joint or lumbar facet joint pain due to this high degree of torsional strain Role of the Spine in Baseball exerted on the low back.4 Poor lumbopelvic control The spine and core musculature are responsible has been shown to be a predictor of subsequent for positioning the head, shoulders, and upper injury, and the degree of lumbopelvic dysfunction is extremities in space over the hips and lower ex- proportional to injury severity in MLB pitchers.5 tremities. Proper maintenance of this relationship is required during all phases of throwing, pitching, Hitting running, and hitting. During these activities, the Similar to pitching, hitting involves a complex com- spine may dynamically flex, extend, rotate, and lat- bination of movements from the upper and lower erally bend as needed to keep the body balanced extremities that must be balanced by the core and with the head centered over the trunk. spine. Although numerous movements occur si- multaneously, rotational motion is primarily respon- Pitching and Throwing sible for generating power. The trunk rotates an Whether pitching from the wind-up or the stretch, average of 46 ± 9° during the swing and reaches the head begins centered over the hips and pelvis. a maximal angular acceleration of 7200 ± 2800°/ As the pitching motion progresses, the hips under- s2 just after contact.9 During this period of rapid go rotation, flexion, extension, abduction, and cir- torsion, the spine must rotate in conjunction with cumduction. While this is occurring, the shoulders the hips and shoulders to create a stable cylinder and upper truck must bend, rotate, and translate and axis of rotation. The spine and core are respon- toward home plate with the body. Just prior to front sible for synchronizing rotation to ensure that hip foot contact, trunk rotation averages 55 ± 6° with and shoulder parallelism is maintained from swing a maximal mean angular acceleration of 11,600 ± initiation to ball contact. If the body does not rotate 3100°/s2. 9 In order for the body to remain balanced, as a unit, the position of the head is affected and controlled, and synchronized throughout this deliv- the batter’s ability to see the ball may be compro- ery, the lumbar spine and core musculature must mised. Additionally, if delivery of the shoulders lags too far behind that of the hips, the position of the hands Table. Common Lumbar Injuries in Baseball (and bat) in space is adversely Etiology Typical Features affected. The entire kinetic chain must remain balanced, / Common in athletes undergoing repetitive back extension coordinated, precisely timed, spondylolysis Present in up to one-third of athletes with and standardized throughout Best diagnosed with bone scan the entire swing from initial Muscle injury Generally follows acute, inciting event trigger to final follow-through. May have history of prior, similar injuries The lumbar spine plays a criti- cal role in each of these steps. Annular tears/ Result from combined compressive and rotatory forces disc herniation Pain can be severe and radiating If lumbar spine mechanics If disc protrusion progresses, radicular symptoms may follow are not sound, this can have significant adverse effects on Facet joint pain Facet joints are typically injured during rotation of the extended back batting performance and may Pain often reproduced by loading facet joint (back extension) predispose hitters to injury.4 Sacroiliac joint pain Presents with deep pain localized to sacroiliac joint Often associated with ankylosing and human leukocyte antigen B27 Common Etiologies for Spinal Injury Stenosis Often presents with slowly progressive pain +/- radicular symptoms The vast majority of baseball Athletes with congenital stenosis may be at increased risk for injury players who experience lumbar

138 The American Journal of Orthopedics ® March/April 2016 www.amjorthopedics.com C. L. Camp et al

pain will have injuries that can be classified as me- lower back pain that may be accompanied by chanical back pain (ie, spondylolysis, annular tears, spasm and pain radiation into the buttock or lower facetogenic pain, SI joint arthropathy, or muscle extremities. Pain is usually worsened by valsalva, injuries) (Table). Although less likely to occur, nerve coughing, sneezing, or bearing down.4 Although entrapment or impingement syndromes (ie, disc annular tears can occur in isolation, they can also herniation, stenosis, and peripheral nerve entrap- lead to herniation of the nucleus pulposus into the ment) have been observed in professional baseball spinal canal (Figure 2). Depending on the location players. Finally, more concerning pathologies such and severity of the herniation, nerve entrapment or as infection and tumor are extremely rare, but impingement can occur. This may initially present they must not be overlooked in this high-demand as pain that radiates into the lower extremities in a patient population. dermatomal fashion. As the herniation progresses, decreased sensation and weakness may develop. Stress Fracture or Spondylolysis In young athletic patients, up to one-third of those Facet Joint Pain with low back pain may have evidence of a lumbar Facetogenic pain can occur stress fracture on bone scan.11,12 This is partic- as the result of degenerative ularly true for athletes who undergo repetitive changes, trauma, or joint in- lumbar extension and rotation, such as linemen, flammation. Facet injury typ- gymnasts, wrestlers, weight lifters, and baseball ically occurs during rotation players.4,13 Although the majority of lumbar stress while the back is extended.4 fractures occur at the pars interarticularis, they can This results in localized pain occur in the pedicle or articular process (Figure and tenderness that can be 1). Most spondylolytic lesions do not progress to reproduced by loading the , especially once patients reach facet joint (lumbar exten- skeletal maturity. Because the fifth lumbar sion) during the examina- represents the transition from the lumbar to the tion, and patients will often sacral spine, most stress fractures occur at L5. demonstrate discomfort Figure 1. Axial computed tomography scan of a These typically present as localized low back pain and altered motion when professional baseball player with low back pain. This imaging confirms a stress fracture of the left that worsens with flexion, extension, and rotation. extending the flexed back. L5 pedicle (white arrow).

Muscle Injury Sacroiliac Joint Pain One of the most common causes of low back pain Although pain in the region in athletes is muscle strains and spasms. Because of the SI joint is very the lumbar paraspinal muscles are extremely active common, much of this during throwing and hitting,10 they are particular- may actually be referred ly susceptible to injury. This is particularly true in from more centrally located deconditioned athletes or those who report to spring neuromotion segments.4 training having not adequately maintained strength SI joint pathology can and flexibility through the off-season.4,5 These injuries occur as a result of trauma, typically present in an acute fashion with an obvious degeneration, or inflamma- inciting incident. Players may have a history of similar tory processes as is seen in muscle injuries in the past. On examination, they (AS). tend to have difficulty maintaining normal posture or Patients with AS typically ranging the spine through a full arc of motion. Local- present with a gradual onset ized, superficial tenderness to palpation in the injured of progressive stiffness and muscle is a key component of the diagnosis. pain in the low back and hips that is worse in the morn- Annular Tears and Disc Herniation ing or following periods of These injuries typically occur as the result of a inactivity. It is most com- combination of compressive and rotary forces on mon in Caucasian males Figure 2. Magnetic resonance imaging of a pro- the lumbar spine that overcome the ability of the in their second to fourth fessional baseball player with low back pain and annulus fibrosus to resist hoop stresses. Patients decades.14 Although 80% radicular symptoms into the left leg. Herniation of the L4-5 disc is evident, resulting in significant with annular tears typically present with severe to 95% of patients with AS stenosis at that level (white arrow). www.amjorthopedics.com March/April 2016 The American Journal of Orthopedics ® 139 Epidemiology, Treatment, and Prevention of Lumbar Spine Injuries in MLB Players

will test positive for human leukocyte antigen B27 ing room, or examination room, paying attention (HLA-B27), it is important to note that the vast to posture, gait, and overall body movement. majority of people with HLA-B27 do not go on to Many patients with lumbar injuries will demon- develop AS.14 Regardless of the cause, SI joint pain strate adaptive patterns of motion in an attempt can be very debilitating and negatively impact all to accommodate their pain. This may be seen baseball-related activities. during baseball-related activities such as throwing, batting, or running. The spine should be visualized Stenosis and palpated for malalignment while standing Lumbar stenosis may develop from arthritic chang- erect and during forward bending. If possible, es, disc protrusion, facet hypertrophy, or ligament motion should be assessed in rotation, lateral ossification. In this young, athletic population, bending, and the flexion and extension planes. congenital stenosis should also be a consideration. Special attention should be paid to any positions Patients with congenital stenosis at baseline are at or maneuvers that reproduce pain or neurologic increased risk for developing neurologic symp- symptoms. Areas of tenderness and radiating pain toms from disc protrusion or other acquired spinal should be fully palpated. A full neurologic examina- pathology. Lumbar stenosis generally manifests as tion consisting of manual muscle testing, sensory a gradual onset of progressive low back pain with examination, and reflex evaluation of both the radicular symptoms or neurogenic claudication.4 upper and lower extremities should be performed. Numerous special tests and neurologic stretch Making the Diagnosis maneuvers that assess specific lumbar nerve roots History have been described.15 When identifying the cause of any musculoskeletal complaint, the diagnosis begins with a thorough Imaging and Diagnostic Tests history. In addition to the standard components Depending on the history and physical examina- of the history, such as timing, severity, tion, imaging of the lumbar spine is not always relation to activity, exacerbating warranted in the acute setting. This is especially factors, associated symptoms, the case if muscle injury, herniation, or annu- and prior treatments, Watkins lar tears are suspected. In cases of persistent and colleagues4 have outlined pain, trauma, or suspected neoplasia, imaging is a number of key factors generally warranted. When x-rays are negative and that should be determined spondylolysis is suspected, bone scan with lumbar when specifically evaluat- single photon emission computed tomography ing the athlete with low (SPECT) is the most sensitive test.16 SPECT scans back pain. These include are positive in active spondylolysis because the ra- quantification of the mor- dio-nucleotide is taken up by active, bone-forming bidity, identification of osteoblasts. Quiescent stress fractures that are contributing psychosocial not apparent on SPECT scans are generally chronic factors, ruling out of urgent and painless.4 If the SPECT scan is positive, the diagnoses (ie, neoplasm, injury can be further characterized by computed infection, rapidly progressive tomography (CT) (Figure 1), which can distinguish neurologic deficits, cauda equi- between spondylolysis, osteoid osteoma, osteo- na, and paralysis), determination of blastoma, acute fracture, or arthritic degeneration. injury type and duration, identification When the SPECT is negative, or if neural impinge- of the clinical syndrome/etiology, pinpoint- ment is suspected, magnetic resonance imaging ing the location of the pathology (what nerve at (MRI) (Figure 2) is likely the best diagnostic imag- what level?), and quantification of back versus leg ing tool. MRI allows identification of bone edema, symptoms. Answers to these questions will set disc herniation, annular disruption, disc desicca- the framework for an appropriately directed physi- tion, stenosis, and nerve entrapment. Finally, when cal examination, imaging, and diagnostic tests. attempting to distinguish between central and peripheral nerve entrapment syndromes, Physical Examination an electromyogram (EMG) or nerve conduction The physical examination begins by observing the study (NCS) is a reliable way to identify the patient or player walk across the playing field, train- location of injury.

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Treatment and Outcomes sists of rest for up to 5 days followed by physical The approach to a patient with low back pain therapy and NSAIDs, Medrol Dose pak, or epidural begins with identification of the etiology and dis- injections.4 Professional baseball players return continuation of the activities that reproduce pain.4 to play at high rates following a herniated lumbar Trunk stabilization exercises and anti-inflamma- disc.6 Earhart and colleagues6 found that 97.1% of tory medications are the mainstays of treatment players returned to play at an average time of 6.6 regardless of the cause of the lumbar spinal injury months from the time of injury. When stratified by in the baseball player.4 position, all pitchers (29 of 29) returned to compet- itive play after operative or nonoperative manage- Stress Fracture or Spondylolysis ment, while 38 of 40 hitters returned.6 The average Management of symptomatic spondylolysis or spon- career length after lumbar disc herniation in the dylolisthesis in the athlete initially consists of conser- professional baseball player is between 4.1 and 5.3 vative treatment, which achieves good to excellent years or between 256 and 471 games.6,23 Other long-term outcomes and return to play in 70% to work has suggested that players undergoing oper- 90% of athletes, especially for acute injuries.17-19 ative treatment for lumbar herniation had shorter After stopping the activity that causes the pain, trunk career lengths; however, patients in the operative stabilization exercises should be started as soon as group tended to be older at the time of injury.23 tolerated with the use of non-steroidal anti-inflamma- Emphasis should be placed on nonoperative tory medications (NSAIDs), oral steroids, and spinal management of baseball players with disc pa- injections to control symptoms and permit initiation thology except in cases of cauda equina syn- of the rehabilitation program.4 Although bracing is drome.4 Hitters and pitchers who require surgery a commonly used adjunctive treatment, a recent have demonstrated decreased 1-year and 3-year meta-analysis did not demonstrate any difference in postoperative statistical performance compared clinical outcomes between patients treated with a to preinjury levels.6 No significant changes in any brace compared to non-braced controls.20 performance statistic were seen in baseball fol- Surgical indications for the treatment of spon- lowing nonoperative management.6 Consequently, dylolysis or spondylolisthesis are limited; however, indications for surgery in the baseball player with failure of nonoperative treatment after 6 months is a lumbar disc pathology includes cauda equina reasonable time to consider surgery.17 The spondylo- syndrome, progressive neurologic deficit, sufficient lytic defect can often be repaired directly using hook morbidity, failure of conservative care, a lesion that screws, translaminar screws, wiring, pedicle screws, can be corrected safely with surgery, and the abili- or image-guided lag screws across the lesion with ty for the patient to comply with a comprehensive grafting.4 Lumbar is less successful in postoperative rehabilitation program.4 Operative professional athletes due to the high demands placed treatment typically consists of a lumbar microdis- on adjacent levels as well as the time required for cectomy and/or laminotomy. 4,6 the fusion to heal.4 Bony union can be determined by a CT scan at 6 months postoperatively if the patient Facet Joint Pain has met appropriate return to play criteria.4 The mainstay of therapy in patients with facet joint pain consists of analgesia and a trunk stabilization Muscle Injury program.24 Lumbar zygapophysial joint injections Management of lumbar sprains and strains and radiofrequency denervation can be considered typically includes restricting painful postures and if the patient fails 4 weeks of directed conservative a rehabilitation program that focuses on core treatment.24,25 Injections may be useful in select strengthening within a pain-free arc of motion.21 patients; however, the literature supporting the use Because acute injuries typically resolve quickly of lumbar facet joint injections or radiofrequency and spontaneously, a short interval of decreased denervation for facetogenic pain is limited.24,25 activity, icing, NSAIDs, and stretching followed by focused strength training is appropriate before Sacroiliac Joint Pain return to sports activity.22 Acute injury of the SI joint can be treated with NSAIDs, icing, and relative rest.26 Mobilization Annular Tears and Disc Herniation of the SI joint in addition to correcting any asym- Initial management of baseball players with acute metries in muscle length or stiffness should be lumbar disc herniation and/or annular tears con- started and progressed as soon as tolerated within www.amjorthopedics.com March/April 2016 The American Journal of Orthopedics ® 141 Epidemiology, Treatment, and Prevention of Lumbar Spine Injuries in MLB Players

a pain-free range of motion.26 Rehabilitation should side bridge position to enhance core activation correct biomechanical deficits and maladaptation along with frontal plane stability. Next, athletes are with a special focus on agonist and antagonist progressed to a half kneeling position and then on muscle groups across the sacrum and ilium.26 to standing. Rotational activities are introduced Treatment of AS in the athlete should emphasize starting with isometric holds progressing to chops/ symptom control, as there is no definite treatment. lifts and rotational medicine ball toss. During these For patients with AS, other long-term therapeutic tasks, focus should be on quality of movement options include sulfasalazine, methotrexate, thalid- and maintenance of core activation. Endurance omide, and anti-tumor necrosis of these muscles should be trained during this factor therapies.14 process. Appropriate pain-free and safe cardiovas- cular exercise, such as walking, biking, swimming, Stenosis and jogging, should be performed throughout Lumbar , whether congenital or each stage in the rehabilitation process. Activities acquired, should initially be managed conservative- should be halted with any increase in pain. At ly.27 Although they do not alter the progression of the completion of the rehabilitation process, it is the disease, epidural steroids and local injections important to observe the athlete while performing may temporarily decrease symptoms in approxi- sport-specific tasks. Spinal stabilization must be mately 40% of cases.27 Those who fail conserva- translational and monitored by observing mainte- tive therapy after 3 months may be candidates for nance of the “cylinder” from the training room to surgical decompression and/or fusion.27,28 However, sports specific movements. surgical treatment for in Since poor lumbar control has been associated elite baseball players has not been thoroughly with increased amount of time on the disabled list,5 studied, so the long-term prognosis is not well it would be ideal to identify those at risk of injury documented.27 before problems arise. Conte and colleagues32 have shown that core muscle strains could be a result Rehabilitation and Prevention of Injuries of muscle imbalance or improper pitching or hitting After an appropriate diagnosis has been made, technique. Other work has demonstrated that pitch- a structured rehabilitation process should com- ers with poor lumbopelvic control did not perform mence. During rehabilitation, it is of primary as well as those with superior control.33 By assess- importance that deep core stabilization is estab- ing spinal stability and biomechanics at baseline, we lished. As an initial step in this process, athletes may be able to identify those at risk. Pitchers with are trained to initiate deep core stabilization with suboptimal spinal stabilization can present with an breathing techniques in a static, supine position.29 unstable balance phase, increased amounts of hy- Proper diaphragm activation with co-contractions perextension of the lumbar spine from the moment of the transverse abdominis (TA) and pelvic floor of max cocking through ball release, as well as has been shown to increase lumbar spine stabili- increased lateral trunk tilt at ball release. Correcting ty.30 This will allow for an increase in intra-abdom- these flaws and increasing deep core stabilization inal pressure (IAP) and improved stabilization of can prevent injuries and improve performance. the lumbar spine, creating a muscular cylinder between the bottom of the rib cage and top of the Summary pelvis. These activities are initiated in the supine A stable, well-functioning lumbar spine is vital to position but are soon advanced as upper and lower nearly every baseball-related activity, including extremity movement against resistance is added. pitching, throwing, batting, fielding, and running. It is important to make sure IAP and contraction of The spine serves as a critical link in the kinetic the TA is maintained throughout this sequence of chain between the upper and lower extremities. progression. Due to the high demand on the lumbar spine, Once deep core stabilization has been estab- injuries to this area represent a significant amount lished, athletes are progressed to global mus- of time out of play in MLB. Initial treatment cle training and kinetic linking in all 3 planes of typically consists of a comprehensive nonoper- movement. This is an important phase, as lumbar ative rehabilitation process involving analgesics, stability is a result of coordinated muscle activation rest, and therapy focusing on core stabilization. involving many muscles.31 This program progress- Because poor lumbopelvic control and mechanics es from supine breathing exercises to a modified have been demonstrated to increase injury risk,

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preemptive spinal and core stabilization is likely LJ. and radiography in young athletes an appropriate step towards injury prevention. with low back pain. AJR Am J Roentgenol. 1985;145(5): 1039-1044. 13. Elliott S, Hutson MA, Wastie ML. Bone scintigraphy in the assessment of spondylolysis in patients attending a sports Dr. Camp is Sports Medicine Fellow, Sports Medicine injury clinic. Clin Radiol. 1988;39(3):269-272. and Shoulder Service, Hospital for Special Surgery, New 14. Kubiak EN, Moskovich R, Errico TJ, Di Cesare PE. Ortho- York, New York. Mr. Conti is a medical student, Weill paedic management of ankylosing spondylitis. J Am Acad Cornell Medical Collage, New York, New York. Mr. Sgroi Orthop Surg. 2005;13(4):267-278. is a Physical Therapist, Sports Medicine and Shoulder 15. Miller KJ. Physical assessment of lower extremity radiculopa- Service, Hospital for Special Surgery, New York, New thy and . J Chiropr Med. 2007;6(2):75-82. 16. Bellah RD, Summerville DA, Treves ST, Micheli LJ. Low-back York. Dr. Cammisa is Attending Orthopedic Surgeon, pain in adolescent athletes: detection of stress injury to the Spine Service, Hospital for Special Surgery, New York, pars interarticularis with SPECT. Radiology. 1991;180(2): New York. Dr. Dines is Associate Professor of Orthopedic 509-512. Surgery, Weill Cornell Medical College, Sports Medicine 17. Radcliff KE, Kalantar SB, Reitman CA. Surgical management and Shoulder Service, Hospital for Special Surgery, New of spondylolysis and spondylolisthesis in athletes: indications York, New York. and return to play. Curr Sports Med Rep. 8(1):35-40. 18. Morita T, Ikata T, Katoh S, Miyake R. Lumbar spondylol- Address correspondence to: Joshua S. Dines, MD, Hos- ysis in children and adolescents. J Bone Joint Surg Br. pital for Special Surgery, 535 East 70th Street, New York, 1995;77(4):620-625. NY 10021 (tel, 516-482-1037; fax, 516-482-9217; email, 19. 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