Femoral shaft fractures in the elderly--role of prior bisphosphonate therapy

There is a recent surge in interest on bisphosphonate related femoral fractures. Most studies have examined subtrochanteric fractures in patients on long-term bisphosphonates. This study evaluates the characteristics of low-impact femoral shaft fractures in elderly patients on long-term alendronate.

All patients above 60 years old admitted to the National University Hospital for femoral shaft fracture from January 2003 to January 2007 were retrospectively analysed. Of the 55 patients included, 7 had prior alendronate therapy and were examined in detail.

All 7 patients on prior alendronate therapy sustained their fractures by low-impact or atraumatic mechanisms of injury. 5 of these 7 patients exhibited a characteristic fracture pattern of thickened lateral cortices at the proximal fracture fragment (p<0.05) and all 7 patients had either transverse or short oblique fractures. Notably, none of the 7 patients had bone mineral density scans prior to their fractures. One patient was started on alendronate after a vertebral compression fracture, whilst the other 6 patients were started on alendronate without any clear clinical indication. All 7 patients reported prodromal thigh pain 3 weeks to 2 years prior to the fracture.

Low-impact femoral shaft fractures in elderly patients on long-term alendronate therapy represent a new entity of insufficiency fractures, with characteristic low-impact modes of injury and fracture patterns on radiograph. Prodromal thigh pain is a warning sign for impending fracture in this group of patients and should be evaluated closely. Teriparatide is a possible alternative to alendronate following such a fracture though more long-term clinical studies are required.