Fig. 5A–B.

We measured the horizontal distance between the most medial aspect of the acetabular floor and the most lateral point of the medial wall of the ischium (acetabular floor to ischial wall distance) in the axial plane passing through the femoral head center as an index of the relative position of the acetabular fossa and the ilioischial line. Acetabular floor to ischial wall distance was expressed as (A) positive when the acetabular floor positioned lateral to the medial wall of the ischium and (B) negative when the acetabular floor positioned medial to the medial wall of the ischium.