A better understanding of the individual anatomy of the human pelvic bones and its influence on the outcome of navigated total hip arthroplasty (THA) may help to improve orthopedic surgery. The goal of this project is to reconstruct reference planes, -axes, and -landmarks from 2d and 3d X-ray data, as well as generating 3d models of the mean male and female pelvic bones from a large set of clinical data. The results of this analysis will be used to find gender-specific differences that are relevant for THA.