Atypical Subtrochanteric and Diaphyseal Femoral Fractures

Yang, Kyu Hyun; Song, Hyung Keun

Abstract

Increasing numbers of atypical subtrochanteric fractures have been reported among long-term bisphosphonate users. However, the nature and extent of the problem are unknown despite recent investigations. The task force of American Society for Bone and Mineral Research (ASBMR) defined major and minor features of complete and incomplete atypical femoral fractures; transverse or short oblique orientation, minimal or no associated trauma, a medial spike when the fracture is complete, and absence of comminution. Minor features include their association with cortical thickening, a periosteal reaction of the lateral cortex, prodromal pain, bilaterality, delayed healing, comorbid conditions, and concomitant drug exposures, including bisphosphonate, glucocorticoids, and proton pump inhibitors. Based on published data, the incidence of atypical femoral fractures associated with bisphosphonate therapy for osteoporosis appears to be very low, particularly compared with the number of vertebral, hip, and other fractures that are prevented by bisphosphonate. Physicians and patients should be aware of the possibility of atypical femoral fractures and of the potential for bilaterality.