Section of a weight bearing anteroposterior pelvic radiograph showing the measurement of pelvic tilt and rotation. Pelvic tilt is assessed by measuring the distance from the upper edge of the symphysis to the sacrococcygeal joint (vertical line with arrowheads). Pelvic rotation is assessed by measuring the widths of the obturator foramens (the horizontal lines) and calculating the foramen obturator index (right foramen width divided by left foramen width).