Femoral Anteversion Angle as a Predictor of Anterior Hip Labral Length in Patients With Femoroacetabular Impingement Syndrome

Background: The relationship between hip rotational abnormalities and hip labral size has not been fully investigated. Purposes: To (1) examine the correlation between rotational abnormalities of the hip and labral size, while also identifying other predictive values for hip labral size, and (2) explore whether femoral torsion will lead to increased labral size. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 180 patients (180 hips) with femoroacetabular impingement syndrome (FAIS) (mean age, 36.81 +/- 10.17 years; 67 male, 113 female) who underwent hip arthroscopic surgery between January 2021 and May 2022 were included. The femoral version (FV), acetabular version, and combined version angles were measured on computed tomography, and the labral length and height at the 12-o'clock and 3-o'clock positions were measured on magnetic resonance imaging. The hips were categorized into 3 groups based on FV angle: small (SFV; <10 degrees); moderate (MFV; >= 10 degrees and <= 20 degrees), and large (LFV; >20 degrees), and group comparisons were performed. Linear correlation and regression analysis were employed. Results: Predictive factors for labral length were FV angle (beta = 0.298; P = .02), sex (beta = -0.302; P < .001), and age (beta = -0.169; P = .016) at 3 o'clock and lateral center-edge angle (LCEA; beta = -0.208; P = .005) and age (beta = -0.186; P = .011) at 12 o'clock. FV angle was positively correlated with labral length at 3 o'clock (r = 0.267; P < .001) and negatively correlated with age (r = -0.222; P = .003) and female sex (r = -0.202; P = .006). LCEA (r = -0.227; P = .002) and age (r = -0.205; P = .006) were negatively correlated with labral length at 12 o'clock. Labral length at 3 o'clock was significantly different between the LFV (n = 49 hips), MFV (n = 65 hips), and SFV (n = 66 hips) groups (9.85 +/- 2.28, 8.89 +/- 2.44, and 8.30 +/- 2.05 mm, respectively; P = .027 for LFV vs MFV; P < .001 for LFV vs SFV). Conclusion: Patients with FAIS who exhibited a higher FV angle were at a greater likelihood of having a larger anterior labral length. Increased femoral anteversion and decreased LCEA, male sex, and younger age were significantly associated with longer hip labral length.