Figure 1. Head-neck translation measurements.
The AOS was defined as the perpendicular distance (ab) between Lines A and B, Line A was drawn parallel to the neck axis and tangential to the convexity of the femoral head; Line B was drawn parallel to the neck axis and tangential to the concavity of the femoral neck21. Similarly, the POS was defined as the perpendicular distance (cd) between Lines C and D, SOS was defined as the perpendicular distance (ef) between Lines E and F, and IOS was defined as the perpendicular distance (gh) between Lines G and H. (AOS, anterior offset; POS, posterior offset; SOS, superior offset; IOS, inferior offset).