Lower extremity stress fractures during intermittent cyclical etidronate treatment for osteoporosis.

During intermittent cyclical etidronate treatment, a lower extremity pain syndrome associated with stress fractures was observed in three osteoporotic patients. This report describes the development of stress fractures during initial cycles of treatment, with recurrence of symptoms in two patients when etidronate therapy was resumed. Further studies are needed to confirm whether stress fractures are associated with cyclic etidronate treatment and if so, the incidence and pathophysiology need to be determined.