Figure 1.

Definition of the PFA and PT. The PFA is defined as the angle between a line drawn from the midpoint of the bilateral femoral head center to the midpoint of the sacral endplate and the proximal femoral shaft axis. The proximal femoral axis is drawn as a line connecting the midpoints of the anterior-most and posterior-most cortices of the proximal and distal portions of the femur (line A). Line B is parallel to line A and passes through the center of the femoral head. The PT is defined as the angle between the plumb line and a line drawn from the midpoint of the bilateral femoral head centers to the midpoint of the sacral endplate. PFA, pelvic femoral angle; PT, pelvic tilt.