Fig. 3

Parameters used to measure acetabular version and axial osseous support. θ5 and θ6 are the anterior acetabular sector angle (AASA) and posterior acetabular sector angle (PASA), respectively. θ7 are the horizontal acetabular sector angle (HASA). θ8 is the acetabular version (AV) described by Anda S. These parameters were measured on were measured on axial images of CT scan at the level of the femoral head center. AASA was measured as the angle between the inter-capital centerline and the line joining the anterior margin of the acetabulum and the femoral head center. PASA was measured as the angle between the inter-capital centerline and the line joining the posterior margin of the acetabulum and femoral head center. HASA was calculated as the summation of AASA (θ5) and PASA (θ6). AV was measured as the angle between the line connecting the anterior and posterior margins of the acetabulum and a line perpendicular to the inter-capital centerline