Bone Biopsy of Atypical Subtrochanteric Fracture in Patient with Prolonged Bisphosphonate Therapy: A Case Report

ABSTRACT

Although alendronate was considered generally safe and effective to osteoporosis in short-long term studies, it remains the potential risk of severely suppressed bone turnover that causes insufficient fracture of femur. In this report, we describe a patient of atypical subtrochanteric fracture who treated with prolonged alendronate. A 68-years old woman who had a history of medication of alendronate for 12 years was presented to the outpatient clinic with right thigh pain. The radiographs revealed thickening and fracture line of the lateral side of subtrochanteric area of the right femur. She discontinued taking the medicine and follow up closely. After 1 month later, she sustained atypical subtrochanteric femoral fracture after simple fall, and underwent an internal fixation with compression hip screw. After operation, bone biopsy was done with tetracycline staining for valuation of bone metabolism and severe osteoporosis was observed. Although long-term use of bisphosphonate could increase bone mineral density, this case showed that it could lead insufficient fracture by decreasing bone strength through severely suppressed bone turnover, inhibition of normal bone formation and decreased bone quality.