Femoral neck shaft angle is not correlated with femoral version: A retrospective study of computed tomography scans.

Background: An understanding of femoral anteversion and neck-shaft angle (NSA) is essential to deliver optimal orthopaedic surgical care. Despite the importance, there is little research examining the relationship between femoral anteversion and the NSA in an adult population. This study sought to determine if there is a correlation between femoral neck shaft angle and version in skeletally mature adults using computed tomography (CT) scanograms.

Methods: Between January 2010 and June 2017, all skeletally mature patients who had received a CT scanogram of the lower extremity were reviewed. Exclusion criteria included: (1) radiographic evidence of osteoarthritis, (2) history of hip, femur, or knee surgery or trauma, (3) and anatomic abnormalities of the proximal femur including prior slipped capital femoral epiphysis or Legg-Calvé-Perthes disease. Both femoral version and NSA were measured by a musculoskeletal fellowship trained radiologist using CT scanograms. Correlation between femoral version and NSA was determined using coefficient of determination (R) and Pearson correlation coefficient (r) for the group as a whole and for each sex.

Results: There was no statistical correlation between femoral version and NSA for either the entire cohort or for each sex. For the entire cohort, R = 0.0016 and r was 0.04 (p=0.45), for females, R = 0.0005 and r was 0.0224 (p=0.72), and for males, R = 0.0342 and r was 0.185 (p=0.07).

Conclusion: There was no correlation between femoral version and NSA. This finding is beneficial for surgeons to understand the proximal femoral anatomy. Patients with an increased femoral NSA should not be assumed to have increased femoral anteversion.

Level Of Evidence: Level III, Retrospective Cohort Study.