Knee Surgery, Sports Traumatology, Arthroscopy

, Volume 27, Issue 10, pp 3125–3132 | Cite as

Age and sex-related distribution of alpha angles and the prevalence of the cam morphology of the hip in Asians do not differ from those of other ethnicities

  • Kee Hyung Rhyu
  • Young Soo Chun
  • Gwang Young Jung
  • Yoon Je ChoEmail author



This study was performed to evaluate the effects of age on the alpha angle and the incidence of asymptomatic cam morphology.


The radiographs of asymptomatic individuals between ages 8 and 22 were retrospectively collected. A total of 1417 individuals were included and grouped according to age: 8–12 (Group A), 13–18 (Group B), and 19–22 (Group C) years. Radiographic measurements of the alpha angles of the right hip were obtained from anteroposterior (AP) and frog-leg lateral (FL) radiographs. The correlations among alpha angles, the presence of cam morphology, and age were determined.


The mean alpha angles of the three groups were statistically different (p < 0.001, each). The alpha angles on both radiographs were positively correlated with age. Intra-group analysis revealed that this correlation was only evident on the FL images of males in Group B. The presence of a radiographic cam morphology also positively correlated with age (p < 0.001 in both AP and FL images). The cam morphology on AP radiographs was 0 in Group A, 17(3.0%) in Group B, and 21(4.8%) in Group C; that on FL radiographs was 2(0.3%) in Group A, 45(7.9%) in Group B, and 103(23.6%) in Group C. Intra-group analysis revealed that the correlation was only significant in males in Group B.


Higher alpha angles and the presence of cam morphology were positively correlated with age, particularly in males at or before the time of skeletal maturation. The prevalence of cam morphology did not differ from those in other ethnicities.

Level of evidence



Hip Age Epiphysis Femoroacetabular impingement Cam Alpha angle Asian 



There was no funding source related to this study.

Compliance with ethical standards

Conflict of interest

KH Rhyu has received research grants from Zimmer-Biomet Korea and Smith and Nephew Korea has received honoraria for speaking at symposia from Amgen Korea is an Editorial Board member of Hip and Pelvis. YS Chun has received research grants from Zimmer-Biomet Korea, Smith and Nephew Korea and Amgen Korea is an Editorial Board member of Journal of Korean Orthopaedic Association. GY Jung has no conflict of interest. YJ Cho is the Editor-in-chief of Hip and Pelvis.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed consent

For this type of study, formal consent is not required.


  1. 1.
    Agricola R, Heijboer MP, Bierma-Zeinstra SM, Verhaar JA, Weinans H, Waarsing JH (2013) Cam impingement causes osteoarthritis of the hip: a nationwide prospective cohort study (CHECK). Ann Rheum Dis 72:918–923CrossRefPubMedGoogle Scholar
  2. 2.
    Agricola R, Heijboer MP, Ginai AZ, Roels P, Zadpoor AA, Verhaar JA et al (2014) A cam deformity is gradually acquired during skeletal maturation in adolescent and young male soccer players: a prospective study with minimum 2-year follow-up. Am J Sports Med 42:798–806CrossRefPubMedGoogle Scholar
  3. 3.
    Barton C, Salineros MJ, Rakhra KS, Beaule PE (2011) Validity of the alpha angle measurement on plain radiographs in the evaluation of cam-type femoroacetabular impingement. Clin Orthop Relat Res 469:464–469CrossRefPubMedGoogle Scholar
  4. 4.
    Beall DP, Sweet CF, Martin HD, Lastine CL, Grayson DE, Ly JQ et al (2005) Imaging findings of femoroacetabular impingement syndrome. Skeletal Radiol 34:691–701CrossRefPubMedGoogle Scholar
  5. 5.
    Beck M, Leunig M, Parvizi J, Boutier V, Wyss D, Ganz R (2004) Anterior femoroacetabular impingement: part II. Midterm results of surgical treatment. Clin Orthop Relat Res 418:67–73CrossRefGoogle Scholar
  6. 6.
    Buck FM, Hodler J, Zanetti M, Dora C, Pfirrmann CW (2011) Ultrasound for the evaluation of femoroacetabular impingement of the cam type. Diagnostic performance of qualitative criteria and alpha angle measurements. Eur Radiol 21:167–175CrossRefPubMedGoogle Scholar
  7. 7.
    Burnett RS, Della Rocca GJ, Prather H, Curry M, Maloney WJ, Clohisy JC (2006) Clinical presentation of patients with tears of the acetabular labrum. J Bone Joint Surg Am 88:1448–1457CrossRefPubMedGoogle Scholar
  8. 8.
    Carsen S, Moroz PJ, Rakhra K, Ward LM, Dunlap H, Hay JA et al (2014) The Otto Aufranc Award. On the etiology of the cam deformity: a cross-sectional pediatric MRI study. Clin Orthop Relat Res 472:430–436CrossRefPubMedGoogle Scholar
  9. 9.
    Cho YJ, Jung GY, Kim EJ, Chun YS, Rhyu KH (2016) Asymmetric epiphyseal closure of the femoral head as a potential cause of the primary cam lesion: a case report. Skeletal Radiol 45:1299–1302CrossRefPubMedGoogle Scholar
  10. 10.
    Clohisy JC, Nunley RM, Otto RJ, Schoenecker PL (2007) The frog-leg lateral radiograph accurately visualized hip cam impingement abnormalities. Clin Orthop Relat Res 462:115–121CrossRefPubMedPubMedCentralGoogle Scholar
  11. 11.
    Eijer H, Myers SR, Ganz R (2001) Anterior femoroacetabular impingement after femoral neck fractures. J Orthop Trauma 15:475–481CrossRefPubMedGoogle Scholar
  12. 12.
    Farr JN, Khosla S (2015) Skeletal changes through the lifespan–from growth to senescence. Nat Rev Endocrinol 11:513–521CrossRefPubMedPubMedCentralGoogle Scholar
  13. 13.
    Gerhardt MB, Romero AA, Silvers HJ, Harris DJ, Watanabe D, Mandelbaum BR (2012) The prevalence of radiographic hip abnormalities in elite soccer players. Am J Sports Med 40:584–588CrossRefPubMedGoogle Scholar
  14. 14.
    Hack K, Di Primio G, Rakhra K, Beaule PE (2010) Prevalence of cam-type femoroacetabular impingement morphology in asymptomatic volunteers. J Bone Joint Surg Am 92:2436–2444CrossRefPubMedGoogle Scholar
  15. 15.
    Hughes LO, Aronson J, Smith HS (1999) Normal radiographic values for cartilage thickness and physeal angle in the pediatric hip. J Pediatr Orthop 19:443–448CrossRefPubMedGoogle Scholar
  16. 16.
    Ida T, Nakamura Y, Hagio T, Naito M (2014) Prevalence and characteristics of cam-type femoroacetabular deformity in 100 hips with symptomatic acetabular dysplasia: a case control study. J Orthop Surg Res 9:93CrossRefPubMedPubMedCentralGoogle Scholar
  17. 17.
    Ito K, Minka MA, Leunig M, Werlen S, Ganz R (2001) Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br 83:171–176CrossRefPubMedGoogle Scholar
  18. 18.
    Johnson AC, Shaman MA, Ryan TG (2012) Femoroacetabular impingement in former high-level youth soccer players. Am J Sports Med 40:1342–1346CrossRefPubMedGoogle Scholar
  19. 19.
    Lee W-Y, Kang C, Hwang D-S, Jeon J-H, Zheng L (2016) Descriptive epidemiology of symptomatic femoroacetabular impingement in young athlete: Single Center study. Hip Pelvis 28:29–34CrossRefPubMedPubMedCentralGoogle Scholar
  20. 20.
    Lerebours F, Robertson W, Neri B, Schulz B, Youm T, Limpisvasti O (2016) Prevalence of cam-type morphology in elite ice hockey players. Am J Sports Med 44:1024–1030CrossRefPubMedGoogle Scholar
  21. 21.
    Leunig M, Beck M, Dora C, Ganz R (2006) Femoroacetabular impingement: trigger for the development of coxarthrosis. Orthopade 35:77–84CrossRefPubMedGoogle Scholar
  22. 22.
    Leunig M, Casillas MM, Hamlet M, Hersche O, Notzli H, Slongo T et al (2000) Slipped capital femoral epiphysis: early mechanical damage to the acetabular cartilage by a prominent femoral metaphysis. Acta Orthop Scand 71:370–375CrossRefPubMedGoogle Scholar
  23. 23.
    Meyer DC, Beck M, Ellis T, Ganz R, Leunig M (2006) Comparison of six radiographic projections to assess femoral head/neck asphericity. Clin Orthop Relat Res 445:181–185PubMedGoogle Scholar
  24. 24.
    Myers SR, Eijer H, Ganz R (1999) Anterior femoroacetabular impingement after periacetabular osteotomy. Clin Orthop Relat Res 363:93–99CrossRefGoogle Scholar
  25. 25.
    Naal FD, Miozzari HH, Wyss TF, Notzli HP (2011) Surgical hip dislocation for the treatment of femoroacetabular impingement in high-level athletes. Am J Sports Med 39:544–550CrossRefPubMedGoogle Scholar
  26. 26.
    Nicholls AS, Kiran A, Pollard TC, Hart DJ, Arden CP, Spector T et al (2011) The association between hip morphology parameters and nineteen-year risk of end-stage osteoarthritis of the hip: a nested case-control study. Arthritis Rheum 63:3392–3400CrossRefPubMedPubMedCentralGoogle Scholar
  27. 27.
    Notzli HP, Wyss TF, Stoecklin CH, Schmid MR, Treiber K, Hodler J (2002) The contour of the femoral head-neck junction as a predictor for the risk of anterior impingement. J Bone Joint Surg Br 84:556–560CrossRefPubMedGoogle Scholar
  28. 28.
    Roels P, Agricola R, Oei EH, Weinans H, Campoli G, Zadpoor AA (2014) Mechanical factors explain development of cam-type deformity. Osteoarthr Cartil 22:2074–2082CrossRefPubMedGoogle Scholar
  29. 29.
    Siebenrock KA, Behning A, Mamisch TC, Schwab JM (2013) Growth plate alteration precedes cam-type deformity in elite basketball players. Clin Orthop Relat Res 471:1084–1091CrossRefPubMedGoogle Scholar
  30. 30.
    Siebenrock KA, Ferner F, Noble PC, Santore RF, Werlen S, Mamisch TC (2011) The cam-type deformity of the proximal femur arises in childhood in response to vigorous sporting activity. Clin Orthop Relat Res 469:3229–3240CrossRefPubMedPubMedCentralGoogle Scholar
  31. 31.
    Snow SW, Keret D, Scarangella S, Bowen JR (1993) Anterior impingement of the femoral head: a late phenomenon of Legg-Calve-Perthes’ disease. J Pediatr Orthop 13:286–289CrossRefPubMedGoogle Scholar
  32. 32.
    Strehl A, Ganz R (2005) Anterior femoroacetabular impingement after healed femoral neck fractures. Unfallchirurg 108:263–273CrossRefPubMedGoogle Scholar
  33. 33.
    Vo A, Beaule PE, Sampaio ML, Rotaru C, Rakhra KS (2015) The femoral head-neck contour varies as a function of physeal development. Bone Joint Res 4:17–22CrossRefPubMedPubMedCentralGoogle Scholar

Copyright information

© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2018

Authors and Affiliations

  1. 1.Department of Orthopaedic SurgeryKyung Hee University HospitalSeoulRepublic of Korea
  2. 2.Department of Orthopaedic SurgeryKyung Hee University Hospital at GangdongSeoulRepublic of Korea

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