| Bisphosphonates are commonly used therapy for the treatment of osteoporosis. It is remarkably effective in preventing both vertebral and non-vertebral fractures. However, the U.S. FDA issued several announcements related to potential risk of long-time use of bisphosphonates, including osteonecrosis of the jaw, atrial fibrillation, and atypical femur fractures in recent years. There is a growing concern of the relationship between long-term use of bisphosphonates and atypical fractures recently. These low-energy fractures are also called fragility fractures. They often occur in femoral sub-trochanteric or femoral shaft. The most commonly accepted etiology is that severe, prolonged over-suppression of bone turnover leads to impaired bone remodeling and microdamage accumulation, resulting in skeletal fragility and thereby predisposing bone to spontaneous fracture. Females, Asian race, Hispanic race, a higher body mass index, long-term use of glucocorticoids, and prolonged exposure to bisphosphonates without cessation are associated with increased risk of atypical femur fractures. American Society for Bone and Mineral Research Task Force recommends that bisphosphonates should be discontinued immediately in the case of atypical fractures, and teriparatide, calcium, and vitamin D should be given. For patients with complete fractures, surgical treatment of intramedullary nail fixation is recommended to protect the whole femur. In conclusion, compared with the classical high-energy fractures, atypical femur fractures have an unique characteristics of pathophysiology, manifestations, and imaging features. Here, we present a review based on recent research and literature retrieval. |