What signs suggest an atypical femur fracture related to antiresorptive therapy?

• A. Gradual thigh or groin pain and subtrochanteric/diaphyseal fracture with minimal trauma
• B. Sudden hip fracture with major trauma
• C. Knee swelling
• D. No symptoms

Answer: (A)

Prolonged antiresorptive therapy can lead to atypical femur fractures, which classically present with gradual thigh or groin pain before a fracture occurs, and the fracture itself tends to be in the subtrochanteric or diaphyseal region with little or no trauma. This prodromal pain reflects suppressed bone remodeling and microdamage accumulation in the femur from long-term therapy, making a fracture more likely even with minimal stress. Therefore, the signs point to an atypical femur fracture when there is progressive thigh or groin discomfort followed by a fracture in the upper femur after minimal trauma. A sudden hip fracture from major trauma, knee swelling, or no symptoms do not align with this pattern.