Cam Morphology Is Associated with Increased Femoral Version: Findings from a Collection of 1,321 Cadaveric Femurs.

Abstract Background To evaluate the relationship between femoral version (FV) and alpha angle (AA) in a large osteological collection of human femora. Methods The University of Iowa-Stanford osteological collection was used to evaluate the research aims. To measure FV and AA, axial photographs of the proximal femora were taken referenced from the posterior condylar axis. FV and AA measurements were obtained using ImageJ software (National Institutes of Health, Bethesda, MD, USA), and the relationship between FV and AA was assessed with repeated measures ANOVA and generalized linear models. A p-value of Results A total of 1321 cadaveric femurs (666 left (L), 655 right (R)) belonging to 721 cadavers were examined. The average AA for all femurs was 47.8 ± 10.9°, and the average FV for all femurs was 8.53 ± 8.09°. Overall, there were 191 of 1321 (14.5%) femurs that exhibited cam morphology (AA ≥ 60°). Of the 721 cadavers, 600 had both femurs available for side-to-side comparison. The average FV of femurs with cam morphology was significantly higher compared to femurs without cam morphology (11.70 ± 8.82 vs 7.99 ± 8.82 (°), p Conclusion In a large osteological collection of human femora, a significant positive relationship between AA and increasing FV was identified. Clinical Relevance FAI and hip impingement morphology is more complex than cam or pincer morphology – cam morphology with high femoral anteversion may allow for normal or near-normal hip mechanics without impingement, and this may partially explain the high rates of asymptomatic cam-type FAI morphology in active and general populations. Given the multiple morphological factors implicated in the development of femoroacetabular impingement (FAI) syndrome, these findings warrant further investigation.