Atypical femur fractures.

Atypical femur fractures were first reported in 2007 and are now recognized as a unique clinical entity. They occur along the shaft of the femur extending from the subtrochanteric region proximally to the distal femoral metaphysis. These fractures have an increased incidence in patients taking bisphosphonates for osteoporosis and develop as stress reactions in the lateral cortex of the femoral shaft. The fractures often have a distinct radiographic appearance with thickening or beaking of the lateral cortex. Treatment should be initiated immediately. There is a higher incidence of complications with atypical fractures. Early detection of these fractures can greatly reduce morbidity.