Fig. 4A–C.

Methods of measuring acetabular version and acetabular sector angles are shown. (A) In this coronal CT slice through the center of the femoral head, the acetabular version is measured in 5-mm increments beginning at the acetabular roof extending distally. (B) In this axial CT slice, acetabular version is the angle formed by the intersection of a line from the anterior to the posterior acetabular margins and a perpendicular line to the transverse axis of the pelvis. (C) The anterior acetabular sector angle (white arrow) is formed by the intersection of a line connecting the center of the femoral head to the anterior edge of the acetabulum and the transverse axis of the pelvis connecting the center of both femoral heads. The posterior acetabular sector angle (black arrow) is the angle formed by the intersection of a line connecting the center of the femoral head to the posterior edge of the acetabulum and the transverse axis of the pelvis connecting the center of the femoral heads.