Comparison of anterior inferior iliac spine morphology between femoroacetabular impingement and developmental dysplasia of the hip: A cohort study in symptomatic patients.

Abstract

Objective: To compare Anterior Inferior Iliac Spine (AIIS) morphology between femoroacetabular impingement (FAI) and developmental dysplasia (DDH) and investigate the correlation between AIIS and hip morphology.

Materials and methods: 374 patients (423 hips) who underwent primary hip arthroscopic surgery were retrospectively reviewed. The inclusion criteria were patients with labral tears and either FAI or DDH. Preoperative demographics and imaging variables were compared. Patient demographics, including age, sex, and body mass index, were assessed. For imaging evaluation, the lateral center edge (LCE), sharp, vertical center anterior (VCA), alpha, and Tönnis angles and AIIS morphology according to Hetsroni's classification were assessed.

Results: 310 patients (359 hips) were included in this study. The FAI cases involved 241 hips (148 males, 93 females), and the DDH cases involved 118 hips (34 males, 84 females). AIIS type 3 included 10 hips (4.1%) in the FAI group and 21 hips (17.8%) in the DDH group. The proportion of AIIS type 3 in the DDH group was significantly higher than that in the FAI group (chi-squared test, p < 0.001). In the FAI group, there were no significant correlations between AIIS and radiographic parameters. In the DDH group, there were significant correlations between AIIS and the LCE (R = -0.279, p = 0.002), VCA (R = -0.194, p = 0.037), and Tönnis (R = 0.241, p = 0.009) angles.

Conclusion: AIIS type 3 was more prevalent in DDH than in FAI patients. In DDH patients, there was a significant correlation between AIIS protrusion and the severity of dysplasia.