RESUMO
INTRODUCTION: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
