Identification and measurement of anterior and posterior anterior wall coverage on XR. A best fit circle is placed to encompass the femoral head. The anterior acetabular wall is identified with the dashed line. The posterior acetabular wall is identified with the solid line. The solid black line bisects the femoral head. Anterior wall coverage is measured from the top of the femoral head (A) to intersection of the anterior acetabular wall and the bisecting femoral head line (B). Posterior wall coverage is measured from the top of the femoral head (A) to the intersection of the posterior acetabular wall and the bisecting femoral head line (C).