SACRAL INSUFFICIENCY FRACTURES - AN UNSUSPECTED CAUSE OF LOW-BACK-PAIN

We describe 10 cases of sacral fractures diagnosed within the rheumato logy department at Southend Hospital over the last 5 yr. All presented with sudden-onset low back pain. The majority were elderly, frail, wi th chronic inflammatory disease (six with rheumatoid arthritis, one wi th polymyalgia rheumatica, one with vasculitis) and had received stero ids. Diagnosis was delayed by the inability of plain radiographs to sh ow these fractures and was ultimately demonstrated by technetium scint igraphy/computed tomography scan. We feel that this diagnosis should b e considered in elderly patients with rheumatoid arthritis or other ri sk factors for osteoporosis who present with low back pain and sacral tenderness. Further clues may be parasymphyseal tenderness (suggesting associated pubic ramus fracture), elevated alkaline phosphatase and p lain radiograph showing pubic ramus fractures or parasymphyseal sclero sis. Patients with this complication generally have a poor prognosis a nd two of our patients have died. Seven required in-patient stay (mean 20 days; range 14-41). The mortality, morbidity and costs incurred in management may be comparable to those of femoral neck fractures.