Background: Cam-type femoroacetabular impingement (FAI) is generally described as being more common in males, with pincer-type FAI being more common in females. The purpose of this study was to determine the effect of sex on FAI subtype, clinical presentation, radiographic findings, and intraoperative findings in patients with symptomatic FAI.
Methods: We compared cohorts of fifty consecutive male and fifty consecutive female patients who were undergoing surgery for symptomatic FAI. Detailed information regarding clinical presentation, radiographic findings, and intraoperative pathology was recorded prospectively and analyzed. FAI subtype was classified on the basis of clinical diagnosis and radiographic evaluation.
Results: Female patients had significantly greater disability at presentation, as measured with use of the modified Harris hip score (mHHS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Hip Disability and Osteoarthritis Outcome Score (HOOS), and the SF-12 (12-Item Short Form Health Survey) physical function subscore (all p ≤ 0.02), despite a significantly lower UCLA (University of California at Los Angeles) activity score (p = 0.03). Female patients had greater hip motion (flexion and internal rotation and external rotation in 90° of flexion; all p ≤ 0.003) and less severe cam-type morphologies (a mean maximum alpha angle of 57.6° compared with 70.8° for males; p < 0.001). Males were significantly more likely to have advanced acetabular cartilage lesions (56% of males compared with 24% of females; p = 0.001) and larger labral tears with more posterior extension of these abnormalities (p < 0.02). Males were more likely than females to have mixed-type FAI and thus a component of pincer-type FAI (combined-type FAI) (62% of males compared with 32% of females; p = 0.003).
Conclusions: We found distinct, sex-dependent disease patterns in patients with symptomatic FAI. Females had more profound symptomatology and milder morphologic abnormalities, while males had a higher activity level, larger morphologic abnormalities, more common combined-type FAI morphologies, and more extensive intra-articular disease.
Level of Evidence: Prognostic Level I. See Instructions for Authors for a complete description of levels of evidence.
1Department of Orthopaedic Surgery, Washington University School of Medicine, One Barnes-Jewish Hospital Plaza, Campus Box 8233, St. Louis, MO 63110. E-mail address for J.J. Nepple: email@example.com