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Radiographic Prevalence of Femoroacetabular Impingement in Collegiate Football PlayersAAOS Exhibit Selection
Ashley L. Kapron, BS1; Andrew E. Anderson, PhD1; Stephen K. Aoki, MD1; Lee G. Phillips, MD1; David J. Petron, MD1; Robert Toth, PA-C1; Christopher L. Peters, MD1
1 Departments of Bioengineering (A.L.K.) and Orthopaedics (A.E.A., S.K.A., L.G.P., D.J.P., R.T., and C.L.P.), University of Utah, 590 Wakara Way, Salt Lake City, UT 84108. E-mail address for A.L. Kapron: Ashley.Kapron@utah.edu. E-mail address for A.E. Anderson: Andrew.Anderson@hsc.utah.edu. E-mail address for S.K. Aoki: Stephen.Aoki@hsc.utah.edu. E-mail address for L.G. Phillips: Lee.Phillips@hsc.utah.edu. E-mail address for D.J. Petron: David.Petron@hsc.utah.edu. E-mail address for R. Toth: Robert.Toth@hsc.utah.edu. E-mail address for C.L. Peters: Chris.Peters@hsc.utah.edu
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Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.

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Investigation performed at the University of Utah, Salt Lake City, Utah

Copyright © 2011 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2011 Oct 05;93(19):e111 1-10. doi: 10.2106/JBJS.K.00544
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The prevalence of femoroacetabular impingement may be greater in athletes than in the general population because of increased loading of the hip during sports. This study evaluated the radiographs of collegiate football players in order to quantify the prevalence of femoroacetabular impingement in asymptomatic athletes.


Sixty-seven male collegiate football players (age, 21 ± 1.9 years) participated in this prospective study. Both hips (n = 134) were evaluated independently by two orthopaedic surgeons for radiographic signs of femoroacetabular impingement. The alpha angle and femoral head-neck offset were measured on frog-leg lateral radiographs. The lateral center-edge angle, acetabular index, crossover sign, and alpha angle were measured on anteroposterior radiographs. Data for continuous variables were averaged between observers prior to assessing prevalence. Cam femoroacetabular impingement was considered to be present if the femoral head-neck offset was <8 mm and/or the alpha angle was >50° on either radiograph. Pincer femoroacetabular impingement was considered to be present if the lateral center-edge angle was >40°, the acetabular index was <0°, and/or a positive crossover sign was detected by both observers.


Ninety-five percent of the 134 hips had at least one sign of cam or pincer impingement, and 77% had more than one sign. Twenty-one percent had only one sign of cam femoroacetabular impingement and 57% had both signs. Fifty-two percent had only one sign of pincer femoroacetabular impingement, 10% had two, and 4% had all three signs. Specifically, 72% had an abnormal alpha angle, 64% had a decreased femoral head-neck offset, 61% had a positive crossover sign, 16% had a decreased acetabular index, and 7% had an increased lateral center-edge angle. Fifty percent of all hips had at least one sign of pincer femoroacetabular impingement and at least one sign of cam impingement. Interobserver and intraobserver repeatability was moderate or better for each measure (range, 0.59 to 0.85).


Morphologic abnormalities associated with cam and pincer femoroacetabular impingement were common in these collegiate football players. The prevalence of cam and pincer femoroacetabular impingement was substantially higher than the previously reported prevalence in the general population.

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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