Aim: The indication of acetabular inclination and anteversion not only depends on definition but also on a correctly aligned patient. Determination of anteversion and inclination according to Sven-Johannsson and Visser were simulated with 3D calculations. The influence of pelvic tilt in relation to the frontal plane was evaluated and visualized.
Method: With 3D calculations of planar X-ray photographs for artificial hip cups the normal vector of the acetabular cup was used to calculate anteversion and inclination.
Results: The main axis of the projected acetabular rim is equally suited to determine the cup orientation as the normal vector of the cup plane. Pelvic tilt of about 10 degrees causes measuring errors of about 8 degrees when measured with conventionally used techniques.
Conclusion: For the correct determination of cup orientation pelvic tilt in relation to the frontal plane has to be accounted for.