Subtrochanteric femoral fractures in patients receiving long-term alendronate therapy: imaging features.

Abstract

A paradoxical association between long-term alendronate therapy and low-energy subtrochanteric femoral fractures has been recently recognized. A retrospective review of 34 such femoral fractures was performed. Subtrochanteric femoral fractures associated with long-term alendronate therapy present with minimal trauma, may be chronic, and when incomplete may be missed. The characteristic imaging features include initial involvement and focal thickening of the lateral cortex, transverse orientation, medial beak, and superior displacement and varus angulation at the fracture site.