Fig. 1.

Correlation between the position of the centre of the femoral head and the prosthesis axis to the proximal femoral axis. Left: Prosthesis axis tilted posterior, the centre of the femoral head shifts backwards, the functional anteversion reduces. Centre: The prosthesis axis corresponds to the proximal femoral axis; functional and rotational anteversion are equal. Right: Prosthesis axis is located in front of the proximal femoral axis (prosthesis is tilted towards anterior); the centre of the femoral head shifts forwards, which increases the functional anteversion. rAV rotatory anteversion (surgically adjusted), fAV functional anteversion (under influence of sagittal tilting)