We developed a mathematical model of the pelvis to evaluate the influence of the pelvis movements on anteversion and inclination of an acetabular cup arbitrarily implanted with 10° of anteversion and 45° of abduction. Measurment were particularly focused on evaluating the influence of a −15 to 15 degrees pelvic rotation around the three space axes.

When considering the anteroposterior axis, the ranges of variation are almost 30° for abduction and 6° for anteversion. When considering vertical and mediolateral axes, the magnitude of variation is 30° for anteversion and 3° for abduction

We demonstrate a close relationship between acetabular cup anteversion and pelvic rotations in all planes. In contrast, acetabular cup abduction is mainly related to the rotation around the anteroposterior axis. The influence of the pelvic position on the evaluation of acetabular cup alignement requires very precise CT measurement protocols to make the evaluation accurate and reproductible.