A 65-year-old postmenopausal woman on long-term alendronate (7 years) presents with prodromal thigh pain and a transverse 'beaking' cortical stress reaction at the lateral subtrochanteric femur. This presentation is consistent with:
- A Stress fracture from osteoporosis
- B Bisphosphonate-associated atypical femoral fracture ✓
- C Pathological fracture from skeletal metastases
- D Avascular necrosis of the femoral shaft
Explanation
Bisphosphonate-associated atypical femoral fractures (AFF) occur in patients on prolonged bisphosphonate therapy (usually >3 years), predominantly in the subtrochanteric or femoral shaft region. The characteristic features include: prodromal thigh pain, transverse or short oblique fracture pattern, 'beaking' or focal periosteal thickening on the lateral cortex, minimal or no trauma, bilateral involvement in ~28%. The pathophysiology is suppression of bone turnover causing accumulation of microdamage. Management includes stopping bisphosphonates and considering prophylactic intramedullary nailing if the cortical thickening progresses.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.