Parasymphyseal and associated insufficiency fractures of the pelvis and sacrum

Eleven post-menopausal women presenting with a parasymphyseal insufficiency fracture of the pubis are reported. The plain radiographs showed delayed healing with a mixed lytic and sclerotic area developed at the fracture site simulating a malignant lesion. Aetiological factors included post-menopausal osteoporosis, rheumatoid arthritis and steroid therapy, previous hip replacement and pelvic radiotherapy. Ten patients had concomitant fractures of the pelvis, including nine with sacral fractures. These were all initially missed on presentation because of the subtle radiographic signs of a longitudinal band of sclerosis, usually bilaterally, in the sacral ala. Bone scanning was shown to be the most sensitive technique in detecting the sacral fractures by demonstrating increased uptake in the sacral ala as well as the other fractures of the pelvis. Computed tomography in three cases was helpful in confirming the presence of fractures and excluding the possibility of malignancy.