Three-Dimensional Morphological Analysis of Sex, Age, and Symmetry of Proximal Femurs from Computed Tomography: Application to Total Hip Arthroplasty.

The success of a total hip arthroplasty is directly related to the ability of the implant to match original femoral morphology. Given this critical relationship, we characterized normal proximal femoral morphology as it relates to sex, age, and symmetry. Sixty abdominopelvic computed tomography (CT) scans (30 male and 30 female, ages 20-85 years old) from patients without any osseous pathology or implants were utilized. Three-dimensional models were constructed from the CT scans using Mimics v19 (Materialize). Thirteen landmarks were placed on each femur model and yielded eight morphological measurements for each femur. Medullary cavity measurements were taken superior to, at the center of, and inferior to the lesser trochanter. Morphological measurements were analyzed by sex, age group, and left versus right. A significant difference was identified between males and females for femoral head height, inferior neck length, minimum neck diameter, neck shaft angle, mediolateral medullary cavity measurement superior to the lesser trochanter and the anteroposterior at the lesser trochanter (P < 0.05). Age was found to correlate with medullary cavity measurements. As previously identified in the literature, differences with respect to the right and left femur were not of practical significance. The results show that sex is critical in determining prosthesis fit with the examined morphological measurements of the proximal femur while age is more important with respect to the medullary cavity. It is also evident that the current practice of using one femur to approximate the opposite is a viable clinical assumption. Clin. Anat., 33:731-738, 2020.