Postoperative ventrodorsal pelvis radiographic view showing the measurement method for evaluating the pelvic canal recovery effect. Pelvic canal diameter ratio equals CE/AB. Hemipelvic canal width ratio equals DE/CD. RR equals blue line/red line (blue line: the craniocaudal length of iliac joint facet in contact with sacral articular surface, red line: the craniocaudal length of sacroiliac joint). The black line is drawn from the spinous process of the sacrum to the pelvic symphysis.