Atypical Femoral Fractures, Bisphosphonates, and Mechanical Stress
ABSTRACT Atypical fractures are stress fractures occurring in the femoral shaft and closely related to bisphosphonate use. We here discuss their radiographic definition and different putative etiologies, apart from mechanical stress. Long time reduction of skeletal remodeling because of bisphosphonate use is thought to allow time for the bone to deteriorate mechanically, resulting in reduced toughness. However, the risk of atypical fracture diminishes rapidly after cessation of treatment, which suggests more acute effects of bisphosphonate use. Microdamage normally accumulates at areas of high stress. Possibly, ongoing bisphosphonate use reduces the ability to resorb and replace areas of microdamage by targeted remodeling. This could lead to crack propagation beyond a point of no return, ending in macroscopic stress fracture.
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ABSTRACT: The causal relationship between chronic use of bisphosphonates and occurrences of atypical femoral fractures has not yet been established. Nonetheless, it is known that their chronic use is more related to fractures with a pattern differing from that of classical osteoporotic fractures. Atypical fractures are still rare events and the benefit from using bisphosphonates remains greater for prevention and treatment of osteoporosis. There are few studies guiding the diagnosis and management of these fractures, thus making it difficult to achieve better results. In this report, we present the case of an elderly patient with an atypical femoral fracture that was managed in accordance with guidance from the American Society for Bone and Mineral Research.Revista Brasileira de Ortopedia 01/2015; 12. DOI:10.1016/j.rbo.2014.08.007