Sacral insufficiency fracture, an unsuspected cause of low-back pain in elderly women.

Sacral insufficiency fractures (SIF) usually occur in elderly women and are secondary to various conditions, mainly postmenopausal or steroid-induced osteoporosis and radiation therapy. They are often overlooked or confused clinically and radiographically with metastatic disease. We report a case of a 72-year-old woman who presented to our department with severe low-back pain. She was thoroughly investigated for the cause of her back pain. Plain X-rays did not reveal any abnormality, but magnetic resonance (MR) scan revealed marked oedema within both sides of the sacrum, suggesting a neoplastic lesion. Bone scintigraphy did show a hyperfixation pattern forming an 'H' in the sacrum which is a characteristic sign of SIF. Computed tomography (CT) confirmed sclerotic changes interpreted as insufficiency fractures through both sacral alae. Increased awareness of these fractures may help to avoid unnecessary investigations and treatment. Bed rest and analgesia followed by rehabilitation provide good relief of symptoms.