A 60-year-old postmenopausal woman on long-term oral bisphosphonate therapy for osteoporosis develops sudden thigh pain and an X-ray shows a transverse fracture of the lateral cortex of the subtrochanteric femur with medial cortical thickening and a 'beaking' pattern. This is best classified as:

• A Pathological fracture from metastatic disease
• B Osteoporotic intertrochanteric fracture
• C Stress fracture from overuse in a runner
• D Atypical femoral fracture associated with prolonged bisphosphonate use ✓

Explanation

Atypical femoral fractures (AFF) are a recognised complication of long-term bisphosphonate therapy (typically after 5 years). They occur in the subtrochanteric or diaphyseal region, are transverse or short oblique, show lateral cortical beaking (due to periosteal stress reaction), and medial cortical thickening. The pathophysiology involves suppressed bone remodelling causing accumulation of microcracks. Management includes cessation of bisphosphonate, calcium/vitamin D supplementation, and intramedullary nailing for complete fractures.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.