A
Medial cortex of the femoral neck
B
Articular surface of the femoral head
C
Medial cortex of the intertrochanteric region
D
Lateral cortex of the subtrochanteric or diaphyseal region
Explanation:The correct option is 'd'. Atypical femur fractures (AFFs) associated with prolonged bisphosphonate use are stress-type fractures that characteristically originate on the tension side (lateral cortex) of the subtrochanteric region or femoral diaphysis. They often present with a thickened lateral cortex (cortical beaking), a transverse or short oblique fracture line, and prodromal thigh pain.
Reference: Shane E, et al. Atypical subtrochanteric and diaphyseal femoral fractures: report of a task force of the American Society for Bone and Mineral Research. J Bone Miner Res. 2010;25(11):2267-2294.