Treatment with bisphosphonates and atypical fractures

In the last twenty five years aminobisphosphonates have became the drugs of choice for the treatment of osteoporosis. They strongly inhibit osteoclastic bone resorption and reduce the incidence of new fractures in patients with established osteoporosis, but their long half-life and their chronic effects on bone physiology are a matter of concern. Theoretically a harmful consequence of a prolonged inhibition of bone remodeling could be the microdamage accumulation, and paradoxically the occurrence of new and atypical fractures. Until now, few cases of these unusual fractures have been reported in the international literature. All these patients shared some common characteristics, apart from the chronic use of bisphosphonates for the treatment of osteoporosis. The more frequent is the atypical location of the fractures. Since the majority happened in one or both femoral shafts, others bones such as sacrum, ischium, ribs and pubic rami could be affected. The fractures were atraumatic or caused by minimal trauma and, in some cases, it was preceded by a prodromal pain in the affected area. All cases had biochemical or histomorphometric evidence of low bone turnover. The aim of this paper is to report three new cases of patients that fulfill with the diagnostic criteria of this new entity, two of them with femoral shaft fractures and the remainder with a pelvis one.