Sexual Dimorphism of Acetabular Anatomy Based on Three-dimensional Computed Tomography Image of Pelvises.

BACKGROUND: The study aimed to compare sex differences in the morphology and spatial orientation of pelvic acetabula to advance the understanding of hip anatomy.

MATERIAL AND METHODS: The study was based on three-dimensional reconstructions of computed tomography images of 50 female and 50 male acetabula. The images were used for spatial analysis of hip acetabula relative to the base of the sacral bone as the plane of reference. Statistical analysis was performed to compare angles relevant to the actual axis of the acetabulum (inclination angle, anteversion angle, tilt angle) as well as the volume and inner surface area of the acetabulum.

RESULTS: Both the inclination and tilt angles of the acetabulum did not differ significantly between the groups, the respective values being: 68.61° and 26.53° in females and 70.56° and 30.19° in males (p>0.05). The anteversion angle was significantly larger for female acetabula (38.27° compared to 32.05° in men, with p=0.0008), while the volume and the inner surface area were significantly smaller in women (p=0.0007 and 0.0001 respectively).

CONCLUSIONS: 1. Acetabular orientation is sex-specific, with female acetabula being more forward-oriented than those of men. 2. The volume and inner surface area of acetabula also differ between the sexes, being smaller in women. 3. Regardless of the plane of reference, sexual dimorphism of the acetabulum is constant. 4. Awareness of the above sex-dependent differences is necessary for preoperative planning before orthopaedic surgeries (such as hip arthroplasty or operative treatment of FAI).