Medicina Sportiva (2018), vol. XIV no 2, 3059-3067 Journal of the Romanian Society

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Patellofemoral pain syndrome: prevalence and coping strategies of amateur runners in Lagos state

Akodu AK, Nwakalor NO Department of Physiotherapy, College of Medicine, University of Lagos, Nigeria

Abstract. Patellofemoral pain syndrome (PFPS) is an overuse injury of the patellofemoral joint which is characterized by pain in the anterior aspect of the knee, aggravated by activities. However little is known about the prevalence and coping strategies of PFPS in amateur runners in Nigeria. This study therefore investigated the prevalence and coping strategies of patellofemoral pain syndrome among amateur runners in Lagos, south west, Nigeria. Material and Method. A cross sectional survey was carried out among 203 amateur runners within the ages of 18-40 years recruited from various sports centers in Lagos state, south west, Nigeria. The instruments used for this research were a 32 item questionnaire of Survey instrument for Natural history, Etiology and Prevalence of Patellofemoral pain Studies (SNAPPS) and pain coping inventory (PCI). Results. The 12month prevalence of PFPS was observed to be 45.3%. There was a high prevalence of PFPS among females 45(53.6%). It was also observed that the coping strategies adopted mostly by the respondents were passive coping strategy 65(70.70%). Sex was significantly associated with 12 months prevalence of PFPS. Conclusion. There was a high prevalence of PFPS among amateur runners in Lagos state with females having a 1.35times higher prevalence than males. Passive coping strategies of worrying and resting were mostly adopted by the respondents. Key words: patellofemoral pain syndrome, prevalence, coping strategies, runners.

Introduction , due to its high impact nature is associated with many injuries, especially in the lower extremities, some of which include: runner’s knee, , muscle cramps especially the hamstrings, ankle , , , Achilles tendonitis, foot blisters and stress fractures (1). Lopes et al (2) asserted that the knee is the most commonly reported location of running-related musculoskeletal pain. Pain in this location often reflects running related overuse injuries such as patellar tedinopathy or patellofemoral pain syndrome (3). These injuries are usually caused by repetitive stress on the same tissue without enough time for recovery or lack of adequate muscle conditioning (4). The most common cause of knee pain is Runner's knee, known medically as patellofemoral pain syndrome (5). Patellofemoral Pain Syndrome (PFPS) is an overuse condition that increases pain and compressive force on the patellofemoral joint with activity and is generally not linked to trauma or known intra articular damage to the knee (6-7). PFPS is characterised by pain in the anterior or retropatella (behind the knee cap) knee‐ region, which is exacerbated during activities that overload the patellofemoral joint such as running, prolonged sitting, stair climbing, kneeling or squatting (8). According to Bebeley et al (5), patellofemoral pain syndrome (Runner’s knee) is due to misalignment of the kneecap in its groove where the kneecap pulls off to one side and rubs on the side of the groove causing both the cartilage on the side of the groove and the cartilage on the back of the kneecap to wear out. The dominant symptom is peripatella or retropatella pain which is often activity related (9). Patellofemoral pain syndrome affects physically active individuals and may account for 25-40% of all knee problems seen in a sports injury clinic (10). Onset can be gradual or the result of a single incident and is often caused by a change in training regime that includes dramatic increase in training time, distance or intensity (11). Its impact may be profound, often reducing the ability of those with patellofemoral pain to perform sporting, physical activity and work-related activities pain free (12).

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The prevalence of PFPS has been reported across several age groups, with females having a higher prevalence than males (10). Postulated risk factors of PFPS include both intrinsic and extrinsic factors with extrinsic factors attributed to training errors and change in frequency and intensity of activity; intrinsic factors including bony, patellar and lower extremity misalignment along with muscle and soft tissue imbalances (13). Researchers generally refer to coping as both conscious and unconscious efforts made by individuals to manage stress and negative feelings that are perceived as a drain on one’s resources (14). Coping strategies refer to the specific efforts, both behavioral and psychological, that people employ to master, tolerate, reduce, or minimize stressful events (15). Efforts have been made to categorize specific coping behaviors as either maladaptive or adaptive (15). Strategies may be adaptive in the short term but prove to be maladaptive in longer term if pain becomes chronic (16). Studies have shown PFPS to be very common especially among adolescents and young adults (17); however there is lack of sufficient and recent epidemiological data regarding the prevalence, and coping strategies of this condition within Lagos, south western, Nigeria. There is no data regarding the prevalence or incidence in other populations, except the military personnel where the annual incidence in men is 3.8% and in women 6.5% with a prevalence of 12% in men and 15% in women (11). Therefore, to understand the severity of PFPS among amateur runners in this environment, it is important to determine the prevalence and coping strategies of PFPS among amateur runners in Lagos south west, Nigeria.

Material and Method A total of two hundred and thirty (203) amateur runners were recruited to participate in this study. They were selected from four sports centers in Lagos, south west, Nigeria: National stadium, Surulere, Teslim Balogun stadium, Surulere, University of Lagos sports center, Akoka and Yaba college of Technology sports center using purposive sampling technique. Included into the study were amateur runners within the ages of 18-40years and amateur runners without physical disability. Excluded from this study were individuals with open wounds on the surface of the knee, individuals diagnosed of knee osteoarthritis, individuals with low back pain. A 32 item questionnaire titled Survey instrument for Natural history, etiology and Prevalence of Patellofemoral pain Studies (SNAPPS) developed by Dey et al, (18)consisting of four sections: that sought information on the identification of participants with knee pain, clinical features of the knee problem, pain or difficulty on a number of activities commonly associated with knee problems and identifying that the location of pain is the patella which discriminate between those with PFPS and other non-specific knee pain. Pain coping inventory (PCI) designed by Kraaimaat and Evers, (19) contains 33 questions, which were pooled into 6 domains of cognitive and behavioral strategies for dealing with pain: pain transformation, distraction, reducing demands, retreating, worrying. These domains can be grouped into pain coping dimensions which include active pain coping dimensions with a maximum of (pain transformation, distraction, reducing demands) and passive pain coping dimensions with a maximum of (retreating, worrying and resting). Before the commencement of this study approval was obtained from the Health research and Ethics Committee of Lagos University Teaching Hospital, Idi-araba, (LUTH) Lagos state (CMUL/HREC/ 05/17/142). Prior to the distribution of copies of the questionnaire, the aim and objectives of the study was clearly explained to the participants. Informed written consent was distributed with each copy of the questionnaire. The participants were assured of the confidentiality of their responses and the questionnaire was collected immediately after completion. All subjects were evaluated by a face-to-face interview technique using a questionnaire form, including demographic such as (age, sex, marital status, educational qualifications and occupation). Data were analyzed using Statistical Package for Social Sciences (SPSS) version 22.0 and summarized using descriptive statistics of mean, standard deviation, frequency, percentages, pie charts and bar charts. An inferential statistics of chi-square was used to determine the association between variables at alpha level of p≤ 0.05.

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Results Two hundred and thirty (230) copies of questionnaire were distributed and a total of 203 (88.3%) copies were returned and valid for analysis. Majority, 119(58.60%) of the study population were males and the mean age was 23.17±3.99years with the age ranging from 18-40 years. Almost all the respondents 194 (95.60%) are single. The mean BMI was 22.06±2.87Kg/m2 (Table1). Majority of respondents 152 (74.90%) had a university degree, while forty-one (20.2%) respondents had secondary education. Majority 141 (69.5%) of respondents were students and 6 (3%) were unemployed (Table1).

Prevalence of knee pain. Table 2 shows the 12 months prevalence of knee pain in the study population as 102(50.25%). Of the one hundred and two respondents who had experienced knee pain recently, majority had never had knee surgery 97(95%), dislocated a kneecap 84(82.40%) or experience knee swelling 72(70.50%).

Table 1. Socio-demographic characteristics of respondents Variables Frequency (n) Percentage (%) Age group (years) 18-24 140 69.0 25-32 56 27.60 33-40 7 3.40 Total 203 100.0 Mean age = 23.17±3.99years Sex Female 84 41.40 Male 119 58.60 Total 203 100.0 Marital status Single 194 95.60 Married 9 4.40 Total 203 100.0 Height 1.50-1.60 18 8.90 1.61-1.80 157 77.30 1.81-2.0 28 13.80 Total 203 100.0 Mean height= 1.73± 0.91m Weight 44-55 38 18.70 56-75 128 63.10 76-95 35 17.20 95-105 2 1.0 Total 203 100.0 Mean weight=66.22 ± 11.15Kg BMI <18.5 24 11.80 18.5-24.9 150 73.90 25.0-29.9 28 13.80 >30.0 1 0.50 Total 203 100.0 Mean BMI= 22.06 ± 2.87Kg/m²

Specific regions of knee pain. Of the one hundred and two respondents with knee pain, twenty (19.61%) of the respondents attributed the pain to always be right-sided while only 6(5.88%) attributed the pain to always be left-sided (Table 3).

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The most common sites of knee pain were the right medial patella 55(53.9%), right lateral patella 56(54.9%) and the right patella 41(40.2%). The same areas on the left were the most common. Over a third of respondents (38.2%) had experienced left lateral patella pain, less than half (41.2%) of them had experienced left medial patella pain and 25.5% of them had experienced left patella pain.

Table 2. Prevalence of knee pain among respondents Frequency Percentage Variables (n) (%) Experienced knee pain in the past year No 101 49.75 Yes 102 50.25 Total 203 100.00 Previous knee surgery No 97 95.00 Left knee only 2 2.00 Right knee only 2 2.00 Both knees 1 1.00 Total 102 100.00 Dislocated knee cap No 84 82.45 Left knee only 6 5.90 Right knee only 8 7.85 Both knees 3 2.90 Total 102 100.00 Swollen knee No 72 70.50 Left knee only 11 10.80 Right knee only 17 16.70 Both knees 2 2.00 Total 102 100.00 Knee pain and discomfort over a month No 30 29.40 Left knee only 17 16.70 Right knee only 35 34.30 Both knees 20 19.60 Total 102 100.00 Been to a doctor for knee problems No 166 81.77 Yes 37 18.23 Total 203 100.00

Prevalence of patellofemoral pain syndrome. The prevalence of PFPS was 92(45.3%) in the general population of amateur runners and 92(90.2%) in the population of amateur runners with knee pain. In the total study population, seventy five (73.50%) respondents experienced PFPS pain and discomfort on the right knee joint while 51(50.00%) experienced PFPS pain and discomfort on the left. Forty two (41.20%)

Medicina Sportiva Patellofemoral pain syndrome: prevalence and coping strategies of amateur runners in Lagos state Akodu AK & all

3063 respondent experienced gradual onset of pain on the right knee and 70(68.60%) respondents had pain for more than one month (Figure 1).

Figure 1. Prevalence of Patellofemoral pain syndrome

Table 3 shows specific regions of knee pain that is indicative of PFPS. Pain in the lateral patella region of the right knee was experienced by most 56(54.9%) of the respondents and on the left knee, pain on the medial patella region was mostly 42(41.2%) experienced by the respondents. Specific regions of knee pain indicative of PEPS. Table 3 shows specific regions of knee pain that is indicative of PFPS. Pain in the lateral patella region of the right knee was experienced by most 56(54.9%) of the respondents and on the left knee, pain on the medial patella region was mostly 42(41.2%) experienced by the respondents.

Table 3. Distribution of complaints of knee pain across sites specific to PFPS Variable Frequency (n) Percentage (%) Right knee Medial patella 55 53.90 Lateral patella 56 54.90 Patella tendon 41 40.20 Left knee Medial patella 42 41.20 Lateral patella 39 28.20 Patella tendon 26 25.20

Pain coping strategies. Table 4 shows the distribution of the domains of the pain coping inventory questionnaire. The mean active coping score was 24.09±5.57 and the mean passive pain coping score was 28.36±6.05. Passive factors were generally higher than active factors except with retreating (5.34±2.49).

Table 4. Distribution of six domains of the pain coping inventory

Coping strategy N Mean ± S.D Active factors Transformation 92 7.37 ± 2.46 Distraction 92 10.29 ± 3.05 Reducing demands 92 6.42 ± 1.97 Passive factors Retreating 92 5.34 ± 2.49 Worrying 92 11.74 ± 3.44 Resting 92 11.28 ± 3.05 Active Pain Coping 92 24.09 ± 5.57 Passive Pain Coping 92 28.36 ± 6.05

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Table 5 shows the dominant pain coping strategy employed by respondents with PFPS. Majority of respondents 65(70.7%) employed passive methods dominantly while only 5 (5.4%) employed both passive and active strategies equally. The most common specific coping strategies were rest 29(31.52%), the use of pain reliever medications 16(17.39%) and massage 15(16.30%). Over a third of respondents 33(35.87%) used medications for their knee pain.

Table 5. Dominance of pain coping factors in respondents with PFPS Variable Frequency (n) Percentage (%) Active factor dominance 22 23.90

Passive factor dominance 65 70.70

Equal use of both factors 5 5.40

Total 92 100.00

Association between sex, age, BMI of respondents and prevalence of PFPS. Table 6 shows the association between the gender, age, BMI of all respondents and prevalence of PFPS. Out of one hundred and nineteen male respondents, forty-seven (39.5%) had PFPS. Out of eighty-four female respondents, forty-five (53.6%) had PFPS. Chi-square test showed that there was a statistically significant association (p=0.047) between sex and prevalence of PFPS. Respondent within the ages of 25- 32 years were reported to have the highest prevalence of PFPS which was 32(57.1%). Chi-square test showed that there was no statistically significant association (p=0.097) between age and prevalence of PFPS (Table 6). There were thirteen (54.20%) underweight respondents, sixty six (44%) normal weight respondents and twelve (42.90%) overweight respondents with PFPS. The only obese (100%) respondent had PFPS. Chi- square test showed that there was no statistically significant association (p=0.954) between BMI and the prevalence of PFPS (Table 6).

Table 6. Association between Sex, age, BMI and 12months prevalence of PFPS PFPS (X2) p-value Yes No Sex Male 47(39.5%) 72(60.5%) Female 45(53.6%) 39(46.4%) 3.94 0.047* Total 92 111 Age group 18-24 58(41.4%) 82(58.6%) 25-32 32(57.1%) 24(42.9%) 2.76 0.097 33-40 2(28.6%) 5(71.4%)

BMI categories Underweight 13(54.2%) 11(45.8%) Normal weight 66(44.0%) 84(56.0%) 0.003 0.954 Overweight 12(42.9%) 16(57.1%) Class I obesity 1(100.0%) 0(0.0%) *Significant at p<0.05; X2= Chi square

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Discussion This study was carried out to investigate the prevalence and coping strategies of amateur runners in Lagos state to Patellofemoral pain syndrome (PFPS). This study revealed that 12 month prevalence of patellofemoral pain syndrome among amateur runners in Lagos state was 45.3%. This high prevalence may be due to the running and an increased rate of activity in the study population. Findings from this study also showed that 50.25% was the prevalence of knee pain among amateur runners in Lagos state, with pain mostly occurring on the right knee. Out of the population with knee pain, the prevalence of runners with knee pain that was attributed to PFPS was 90.24%. The other causes of pain in the knee could be due to soft tissue injuries (meniscal tears, anterior cruciate ligament injuries). An insight into the socio-demographic data of the respondents revealed that a high percentage of the participants were students and employed individuals. The high prevalence of PFPS can be attributed to most of the study population being active individuals who are involved in other activities asides running. Although there were more male participants than females, the percentages of PFPS in males and females were 39.50% and 53.60% respectively. PFPS was 1.35times prevalent in females than males. This is slightly lower than 1.5times prevalence in females than males postulated by Taunton et al, (20). The high prevalence in females than males also corroborates with previous studies that proved this sex difference in the prevalence of PFPS (21, 22). This may be due to some anatomic factors such as the increased pelvic width, which results in an excessive lateral thrust on the patella or weak quadriceps muscle strength (11). There was however an association between sex and prevalence of patellofemoral pain syndrome. Participants recruited for this study were between the ages of 18-40years. From the socio- demographic data of the respondents, it was shown that most of the respondents were between the ages of 18-24years, however findings from this study revealed that there was no statistical significant association between age and 12 months prevalence of PFPS. The reason for this is unclear but it may be due to unequal number of age groups of respondents being recruited for the study. Nonetheless this corroborates with findings of previous studies (23, 24). In this present study, PFPS was found to be more prevalent in respondents between the ages of 25-32 years. On the contrary, Glaviano et al, (25) in their study discovered that PFPS was more prevalent in individuals between the ages 50-59years. The result of this study revealed that most of the respondents were within normal BMI range (18.5- 24.9Kg/m2) and there was no significant association between BMI and 12 months prevalence of PFPS. Previous researches have been conflicting regarding the association between BMI and PFPS. Some studies reported a correlation between those with a lower BMI score and PFPS (23, 26) while theories supporting a correlation between an increase in BMI and PFPS and other knee injuries attributed it to BMI and its relation to decreased joint space in the knee (27) and BMI and its relation to an increased Q-angle in the lower extremity (28). From this study, it was discovered that the study population demonstrated higher passive pain coping strategies than active coping strategies. This report is in agreement with the study carried out by Perrot et al, (29) which showed that chronic pain patients demonstrated more passive coping strategies than active coping strategies. Worrying was the highest score of the passive pain coping strategies adopted by majority of the respondents. Worrying refers to maladaptive thoughts concerning the interpretation and prediction of pain. Although not quite identical, the Worrying scale bears close resemblance to the so-called “catastrophizing” scales in other pain coping questionnaires (Coping Strategies Questionnaire CSQ, Pain cognition List PCL) (23). The result of this present study therefore supports the research carried out by Thomee et al, (30) that showed high score of “catastrophizing" among individuals with PFPS. This might be due to the fear of being limited in physical function, fear of being disabled and poor quality of life, as pain has a major impact on functioning. Respondents utilizing active coping strategies mostly adopted distraction as a means of coping with pain. Results of this study also showed that the passive coping strategy score of retreating was the least utilized form of coping with pain from PFPS. Most of the amateur runners with PFPS did not use medications for their pain. Majority of the respondents implied that resting was their own personal way of coping with the pain.

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Conclusion There was a high prevalence of PFPS among amateur runners in Lagos, South west Nigeria. Females have higher prevalence of PFPS than males. There is no association between age, BMI and prevalence of PFPS among amateur runners in Lagos state. Worrying was the most utilized coping strategies among the respondents. It was therefore recommended that there should be increase in the awareness of patellofemoral pain syndrome especially among athletes. There should also be awareness on ways of coping with pain associated with PFPS in amateur runners

Conflicting Interest. The authors declared that they have no competing interest. Acknowledgement. The authors appreciate the contribution of the participants that were involved in this study.

Reference 1. Ogwumike O, Adeniyi A (2015). The SPLASH/ICPC integrity marathon in Ibadan, Nigeria: incidence and management of injuries and marathon-related health problems. BMC Sports Science, Medicine and Rehabilitation; 5:6. 2. Lopes AD, Costa LO, Saragiotto BT, Yamato TP, Adami F, Verhagen E (2011). Musculoskeletal pain is prevalent among recreational runners who are about to compete: an observational study of 1049 runners. Journal of physiotherapy; 57(3): 179-82. 3. Fredericson M, Misra AK (2007). Epidemiology and aetiology of marathon running injuries. Sports Medicine; 37: 437-39. 4. Möhlenkamp S, Lehmann N, Breuckmann F, Bröcker-Preuss M, Nassenstein K , Halle M, et al (2008). Running: the risk of coronary events: Prevalence and prognostic relevance of coronary atherosclerosis in marathon runners. European Heart Journal; 29(15): 1903-10. 5. Bebeley SJ, Yi-gang W, Yang L (2016). Athletes’ Knowledge about Preventing Sports Injuries like: (AT), Runner’s Knee (RK)/Patellofemoral Pain Syndrome (PFPS) and Shin Splints (SS), as Prime Prevention Strategies in Slowing Ageing Process. Journal of Exercise Science & Physiotherapy; 12(1): 25-37. 6. Davis IS, Powers CM (2010). Patellofemoral pain syndrome: Proximal, distal, and local factors, an international retreat, April 30-May 2, 2009, Fells Point, Baltimore, MD. Journal of Orthopaedics and sports physical therapy; 40(3): A1-16. 7. Bolgla LA, Boling MC (2011). An update for the conservative management of patellofemoral pain syndrome: A systematic review of the literature from 2000 to 2010. International Journal of Sports Physical Therapy; 6(2): 112-125. 8. Martimbianco ALC, Torloni MR, Andriolo BNG, Porfirio G, Riera R (2014). Neuromuscular electrical stimulation (NMES) for patellofemoral pain syndrome (Protocol). Cochrane Database of Systematic Reviews 2014: 9. 9. Al-Hakim W, Kumar JP, Khan W, Johnstone D (2012). The non-operative treatment of anterior knee pain. The Open Orthopaedics Journal; 6:320–6. 10. Boling M, Padua D, Marshall S, Guskiewicz K, Pyne S, Beutler A (2010). Gender differences in the incidence and prevalence of patellofemoral pain syndrome. Scandinavian Journal of Medicine and Science in Sports; 20(5): 725-30. 11. Heintjes E, Berger MY, Bierma-Zeinstra SM, Bernsen RM, Verhaar JA, Koes BW (2004). Pharmacotherapy for patellofemoral pain syndrome. Cochrane Database Systematic Review 3. 12. Crossley KM, Stefanik JJ, Selfe J, Collins NJ, Davis IS, Powers CM et al (2016). Patellofemoral pain consensus statement from the 4th International Patellofemoral Pain Research Retreat, Manchester. Part 1: Terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported outcome measures. British Journal of Sports Medicine; 50: 839-843. 13. Hryvniak D, Magrum E, Wilder, R (2014). Patellofemoral Pain Syndrome. Current Physical Medicine and Rehabilitation Reports; 2:16. 14. Franco RL, Cano Garcíaa FJ, Blanco PA (2004). Assessment of chronic pain coping strategies Actas Esp Psiquiatr; 32(2): 82-9182 15. Englbrecht M, Gossec L, DeLongis A, Scholte-Voshaar M, Sokka T, Kvien TK, et al (2012). The impact of coping strategies on mental and physical well-being in patients with rheumatoid arthritis. Seminars in arthritis and rheumatism; 41(4): 545-55. 16. Jensen MP, TurnerJA, Romano JM, Karoly P (1991). Coping with chronic pain: a critical review of the literature. Pain; 47(3): 249-83. 17. Stovitz SD, Pardee PE, Vazquez G, Duval S, Schwimmer JB (2008). Musculoskeletal pain in obese children and adolescents. Acta Paediatr; 97(4): 489-93. 18. Dey P, Callaghan M, Cook N, Sephton R, Sutton C, Hough E (2016). A questionnaire to identify patellofemoral pain in the community: an exploration of measurement properties. BMC Musculoskeletal Disorders; 17: 237.

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19. Kraaimaat FW, Evers AWM (2003). Pain-coping strategies in coping pain patients: psychometric characteristics of the pain-coping inventory (PCI). International journal of behavioral medicine; 10(4): 343-63. 20. Taunton J, Ryan M, Clement D, McKenzie D, Lloyd-Smith D, Zumb B (2002). A retrospective case-control analysis of 2002 running injuries. British journal of sports medicine; 36(2): 95–101. 21. Fulkerson JP, Arendt EA (2000). Anterior knee pain in females. Clinical orthopaedics and clinical research; 372: 69-73. 22. Nejati P, Forogh B, Moeineddin R, Baradaran H, Nejati M (2011). Patellofemoral pain syndrome in iranian female athletes. Acta Medica Iranica; 49(3): 169-72. 23. Duvigneaud N, Bernard E, Stevens V, Witvrouw E, Van Tiggelen D (2008). Isokinetic assessment of patellofemoral pain syndrome: a prospective study in female recruits. Isokinetic Exercise Science; 16(4): 213–19. 24. Van Tiggelen D, Cowan S Coorevits P, Duvigneaud N, Witvrouw E (2009). Delayed vastus medialis obliquus to vastus lateralis onset timing contributes to the development of patellofemoral pain in previously healthy men: a prospective study. American Journal of Sports Medicine; 37: 1099-1105. 25. Glaviano NR, Kew M, Joseph M, Saliba S (2015). Demographic and epidemiological trends in patellofemoral pain. International Journal of Sports and Physicial therapy; 10(3): 281–290. 26. Collins NJ, Crossley KM, Darnell R, Vicenzino B (2010). Predictors of short and long term outcome in patellofemoral pain syndrome: a prospective longitudinal study. BMC Musculoskeletal Disorders; 11: 11. 27. Richmond SA, Kang J, Emery CA (2013). Is body mass index a risk factor for sport injury in adolescents? Journal of Science and Medicine in Sport; 16: 401–4035. 28. Yard E, Comstock D (2011). Injury patterns by body mass index in US high school athletes. Journal of Physical Activity and Health; 8(2): 182–191. 29. Perrot S, Poiraudeau S, Kabir M, Bertin P, Sichere P, Serrie A, et al (2008). Active or passive pain coping strategies in hip and knee osteoarthritis. Arthritis care Research; 59(11): 1555-62. 30. Thomeé P, Thomeé R, Karlsson J (2002). Patellofemoral pain syndrome: pain, coping strategies and degree of well- being. Scandinavian Journal of Medicine Science and Sports; 12(5): 276-81.

Corresponding author Akodu AK Department of Physiotherapy, College of Medicine, University of Lagos, Nigeria E-mail address: [email protected], [email protected]

Received: October 24, 2018 Accepted: December 10, 2018

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