Looking beyond low bone mineral density: multiple insufficiency fractures in a woman with post-menopausal osteoporosis on alendronate therapy.

Insufficiency fractures occur most commonly in the pelvic girdle and in the sacrum, followed by the tibia and the femoral neck. Insufficiency fractures of the femoral diaphyses are rare, with only few reported cases in the literature. The strongest associations exist with untreated osteoporosis. We describe an unusual case of multiple insufficiency fractures in a 73-yr-old Chinese woman who presented with a 10-month history of bilateral groin pain and difficulty with walking in the absence of trauma, diagnosed 18 months following the commencement of anti-resorptive therapy with alendronate. The pathogenesis of such insufficiency fractures is poorly understood, but next to low bone mineral density and micro-architectural damage likely involves other components such as changes in bone turnover and patient-related factors (e.g. non-compliance). This case report and review of the literature draws attention to some of the challenges in the diagnosis and management of such rare insufficiency fractures.