Osteoporosis (OP) results from an imbalance between bone production and absorption that results in decreased bone mass and microstructural deterioration of the bone trabeculae, leading to diminished bone quality and fragility fractures. It is synonymous with decreased bone strength and affects millions of people worldwide. The most commonly prescribed drugs for the treatment of OP are the bisphosphonates (BPs). Long-term BP use may be associated with stress fractures of the subtrochanteric and shaft regions of the femur known as atypical femur fractures (AFFs). Although AFFs can be devastating, BPs have decreased the number of low-energy hip fractures and the number of vertebral and nonvertebral fractures that occur each year. Many trials and population-based studies have assessed the association between AFF and BP, and several studies have attempted to establish AFF's true incidence. The authors will summarize a few of the major studies and discuss their strengths and limitations. The findings of an association between BPs and AFFs have been variable and may reflect sample selection and measurement bias. AFFs are uncommon; the increase in risk associated with BP use is very small and does not outweigh the benefit of fracture prevention in patients with OP. Evidence for the efficacy of BPs for the prevention of fractures in postmenopausal women with OP is very strong, and the current clinical practice of using BPs as first-line therapy for these patients should be continued. Further information is required to determine the appropriate duration and time of discontinuation of BP therapy.
