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What causes cam deformity and femoroacetabular impingement: still too many questions to provide clear answers
  1. Rintje Agricola1,
  2. Harrie Weinans2,3
  1. 1 Department of Orthopaedics, Erasmus University Medical Center, Rotterdam, The Netherlands
  2. 2 Department of Orthopaedics and Department of Rheumatology, University Medical Center Utrecht, Utrecht, The Netherlands
  3. 3 Department of Biomechanical Engineering, Technical University Delft, Delft, The Netherlands
  1. Correspondence to Rintje Agricola, Department of Orthopaedics, Erasmus University Medical Center, Room EE16-14, P.O. Box 2040, Rotterdam 3000 CA, The Netherlands; r.agricola{at}

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Cam deformities of the femoral head contribute to femoroacetabular impingement (FAI) and correlates strongly with development of osteoarthritis.1 Surgery on patients with FAI is performed with increasing frequency; it is unknown whether this prevents osteoarthritis in later life.2 As cam deformity is triggered during late puberty by impact loading of the hip, it is important to elucidate the aetiology of cam deformity.

Factors associated with the presence of a cam deformity

Sex, genetics and physical activity appear to influence whether or not a cam deformity develops. The prevalence of cam deformity is as high as 89% in athletes participating in activities that result in impact loading of the hip as compared to only 9% in non-athletic controls.3 What explains these differences? More than 40 years ago, Murray and Duncan4 recognised that by the loads applied to the hip during skeletal growth influenced, at least in part, development of a cam deformity. They postulated that cam deformity resulted from a mild undiagnosed slipped capital femoral epiphysis (SCFE) in young athletes but recent studies in adolescent athletes suggest SCFE is not involved.5 Hence, cam deformity result from bone adaptation in response to vigorous hip loading, which means that it should be …

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  • Contributors Both authors contributed equally. The final version was approved by both authors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.