Figure 3

DRR image (a) and standing radiograph (b). Adjust the pelvic inclination (c) so that the vertical-to-horizontal ratio of the pelvic foramen is the same between (a) and (b). The arrows indicate the vertical distance between the bilateral sacroiliac joints and pubic symphysis and the maximum horizontal diameter of the pelvic foramen. The pelvic inclination was defined as the angle between the solid line (z-axis) and the dotted line (APP). (d) VCA angle was measured as the angle between the vertical line and a line connecting the femoral head center and the anterior end of the acetabulum after adjustment to the standing position. The dotted line indicates APP. (e) DRR image of the FP radiograph (rotating AP image 65° in the axial plane), ± 5° and ± 10°relative to the FP radiograph (rotating AP image 55°, 60°, 70°, 75°in the axial plane). Indicates a change of sourcil edge with pelvic rotation. The ACEA was measured for each DRR image. DRR Digitally reconstructed radiography, APP Anterior pelvic plane, VCA Vertical-center-anterior, FP False profile, AP Anterior–posterior, ACEA Anterior center edge angle.