Gender differences in 3D morphology and bony impingement of human hips.

For the proper diagnosis or treatment of hip joint disorders caused by anatomical abnormalities, the normal hip joint morphology must be studied to understand its influence on the maximum range of motion (ROM) until bony impingement by focusing on gender differences. Acetabular and femoral morphologies were analyzed from 3D CT images of 106 normal hip joints from elderly men (n = 36 joints) and women (n = 70 joints), and measurements of ROM until bony impingement were made in four directions (flexion, extension, and external and internal rotation at 90° flexion) using surface models of the pelvis and femur reconstructed from the CT data. Gender differences were found not only in joint orientation, including anteversion and inclination of the acetabulum and femoral neck anteversion, but also in the shape around the joint, including the acetabular rim and the femoral neck. This ROM study also showed gender differences in all four standard directions. In conclusion, significant gender differences were observed in the acetabular and femoral morphology, which led to significant gender differences in ROM until bony impingement.