The Cam-type Deformity of the Proximal Femur Arises in Childhood in Response to Vigorous Sporting Activity

  • K. A. SiebenrockEmail author
  • F. Ferner
  • P. C. Noble
  • R. F. Santore
  • S. Werlen
  • T. C. Mamisch
Clinical Research



The prevalence of a cam-type deformity in athletes and its association with vigorous sports activities during and after the growth period is unknown.


We therefore compared the prevalence and occurrence of a cam-type deformity by MRI in athletes during childhood and adolescence with an age-matched control group.

Patients and Methods

We retrospectively reviewed 72 hips in 37 male basketball players with a mean age of 17.6 years (range, 9–25 years) and 76 asymptomatic hips of 38 age-matched volunteers who had not participated in sporting activities at a high level.


Eleven (15%) of the 72 hips in the athletes were painful and had positive anterior impingement tests on physical examination. Internal rotation of the hip averaged 30.1° (range, 15°–45°) in the control group compared with only 18.9° (range, 0°–45°) in the athletes. The maximum value of the alpha angle throughout the anterosuperior head segment was larger in the athletes (average, 60.5° ± 9°), compared with the control group (47.4° ± 4°). These differences became more pronounced after closure of the capital growth plate. Overall, the athletes had a 10-fold increased likelihood of having an alpha angle greater than 55° at least at one measurement position.


Our observations suggest a high intensity of sports activity during adolescence is associated with a substantial increase in the risk of cam-type impingement. These patients also may be at increased risk of subsequent development of secondary coxarthrosis.

Level of Evidence

Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.


Internal Rotation Proximal Femur Sport Activity Alpha Angle Male Athlete 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© The Association of Bone and Joint Surgeons® 2011

Authors and Affiliations

  • K. A. Siebenrock
    • 1
    Email author
  • F. Ferner
    • 1
  • P. C. Noble
    • 2
  • R. F. Santore
    • 3
  • S. Werlen
    • 4
  • T. C. Mamisch
    • 1
  1. 1.Department of Orthopedic SurgeryUniversity of BernBernSwitzerland
  2. 2.Joseph Barnhart Department of Orthopedic SurgeryBaylor College of MedicineHoustonUSA
  3. 3.Department of Orthopedic SurgeryUniversity of California, Sharp Memorial HospitalSan DiegoUSA
  4. 4.Department of RadiologySonnenhof ClinicBernSwitzerland

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