Radiographic features of pelvic instability

A standing AP radiograph of pelvis shows findings associated with underlying pelvic instability: (1) pelvic tilt secondary to leg length discrepancy; (2) degenerative changes at the symphysis pubis which include joint space narrowing, articular cortical irregularity and subchondral sclerosis; (3) slight pubic malalignment with associated traction osteophyte at the superior joint margin; (4) widening of the right sacroiliac joint inferiorly (arrowhead); and (5) ossification at the left adductor origin secondary to an old tear (arrow). Not all such changes are seen in all cases.