Unstable pelvic insufficiency fracture in a patient with rheumatoid arthritis.

The occurrence of pelvic insufficiency fractures in patients with rheumatoid arthritis has not previously been well emphasized. These fractures are difficult to detect clinically, and appropriate radiological investigation is necessary for diagnosis. A 72-year-old woman with rheumatoid arthritis presented with severe left groin pain. Pelvic radiographs showed parasymphyseal fractures, and marked instability of these fractures was observed at the follow-up 2 weeks later. Computed tomographic scan of the sacrum showed a widened linear fracture gap in the left sacral ala. Because the patient's pain was so severe that she could not change position, external fixation was performed to achieve rapid pain relief and early mobilization. Although most patients with these fractures respond well to simple conservative treatments, parasymphyseal fractures combined with sacral fractures may cause disruption of the pelvic ring and occasionally need operative management.