Femoro-Epiphyseal Acetabular Roof (FEAR) index and anterior acetabular coverage correlate with labral length in developmental dysplasia of the hip.

PURPOSE The aim of this study was to evaluate the association between labral length and radiographic parameters of lateral and anterior acetabular coverage and the femoro-epiphyseal acetabular roof (FEAR) index in patients with developmental dysplasia of the hip (DDH). METHODS We retrospectively analyzed data from patients with DDH who visited our hip joint clinic for the first time due to hip symptoms. DDH presence was defined as a lateral center-edge angle (LCEA) ≤ 25°. The labral lengths on the anterior and lateral sides were measured on central axial and central coronal slice of T1-weighted magnetic resonance imaging, respectively. The Pearson's correlation coefficients (r) and simple linear regression analyses were performed to determine the association of the lateral and anterior labral lengths with the radiographic parameters including the LCEA, acetabular roof obliquity (ARO), FEAR index, anterior wall index, and vertical center anterior (VCA) angle. RESULTS This study included 88 patients, with a mean age of 39.6 ± 11.8 years. There were 65 women and 23 men. The lateral and anterior labral lengths correlated with all parameters of dysplasia. Specifically, the lateral labral length had a strong positive correlation with the FEAR index (R = 0.65, p < 0.001). The anterior labral length had a strong negative correlation with the anterior wall index (R = -0.66, p < 0.001). CONCLUSIONS The lateral labral length had a strong positive correlation with the FEAR index. Furthermore, the anterior labral length had a correlation with the anterior dysplasia. LEVEL OF EVIDENCE Ⅲ (retrospective cross-sectional study).