Femoral Neck Anteversion and Lesser Trochanteric Retroversion in Patients With Ischiofemoral Impingement: A Case-Control Magnetic Resonance Imaging Study

Purpose: To assess the relationship between the femoral neck version (FNV) and lesser trochanteric version (LTV) in symptomatic patients with ischiofemoral impingement (IFI) as compared with asymptomatic hips. Methods: The FNV and LTV of patients with symptomatic IFI who underwent magnetic resonance imaging assessment including a standardized femoral version study protocol were compared with those of patients with asymptomatic hips in this retrospective, observational study. Patients with isolated intra-articular pathology, prior hip fracture, and lesser trochanter deformity were excluded. The FNV, LTV, ischiofemoral space, and quadratus femoris space were evaluated on axial magnetic resonance imaging, as well as the angle between the LTV and the FNV. Independent t-tests were used to determine differences between groups. Results: Data from 11 out 15 symptomatic patients and 250 out of 320 asymptomatic patients were analyzed. The mean ischiofemoral space (11.9 v 22.9 mm; P < .001; 95% confidence interval [CI], 6.9 to 15.2) and mean quadratus femoris space (7.2 mm v 14.9 mm; P < .001; 95% CI, 5.4 to 8.6) were significantly smaller in symptomatic patients versus asymptomatic patients. There was no difference in mean LTV between groups (-23.6 degrees v -24.2 degrees; P = .8; 95% CI, -7.5 to 6.4), however, the mean FNV (21.7 degrees v 14.1 degrees; P = .02; 95% CI, -14.2 to -1.1) and the angle between the FNV and LTV on average (45.4 degrees v 38.3 degrees; P = .01; 95% CI, -12.9 to -1.3) were higher in symptomatic than in asymptomatic patients, with statistical significance. Conclusions: The femoral mean neck anteversion and the mean angle between the FNV and LTV are significantly higher in patients with symptomatic IFI. The mean LTV is not increased in patients with symptomatic ischiofemoral impingement as compared with those patients with asymptomatic hips.