Fig. 2.

Measurement of the acetabular version angle in four axial slices. (A) Reference plane for measuring the acetabular version angle. Each line represents one of the four slices; a slice at the level of the superior margin of the femoral head (slice A1), a slice 5 mm below the superior margin of the femoral head (slice A2), a slice 10 mm below the superior margin of the femoral head (slice A3) and a slice 15 mm below the superior margin of the femoral head (slice A4). (B) Axial slice of A1. Angle ø is the acetabular version angle.