A 65-year-old woman on long-term bisphosphonate therapy for osteoporosis presents with a low-energy subtrochanteric femoral fracture. Plain X-ray shows a transverse fracture with cortical thickening of the lateral cortex and a 'beaking' pattern. This is classified as:

• A Pathological fracture from metastatic disease
• B Atypical femoral fracture (AFF) associated with prolonged bisphosphonate use ✓
• C Intertrochanteric fracture with subtrochanteric extension
• D Periprosthetic fracture from an unrecognized hip arthroplasty

Explanation

Atypical femoral fractures (AFF) are a recognized complication of prolonged bisphosphonate use (>3-5 years), resulting from impaired bone remodeling that allows accumulation of microdamage. ASBMR criteria: location subtrochanteric/femoral shaft, transverse or short oblique pattern, non-comminuted, lateral cortex thickening (beaking/flaring), no trauma or minimal trauma. Mechanism: bisphosphonates suppress osteoclast activity, preventing repair of fatigue cracks, leading to stress fractures. Treatment: cephalomedullary nail. Bisphosphonate should be withheld. Contralateral femur should be X-rayed as bilateral occurrence is common.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.