594 - Bisphosphonates and Atypical Fractures: A Cautionary Case

Case Diagnosis: Atypical Femoral Shaft Fracture in Prolonged Bisphosphonates Use in a 94-year-old female with history of osteoporosis, unprovoked pulmonary embolism on anticoagulation who presented with left lower extremity pain.

Case Description: Patient states that while transferring from sit to stand position she twisted her leg experiencing pain and inability to bear weight with worsening pain over one week. X-ray imaging of left femur revealed an acute oblique displaced fracture of left proximal femoral diaphysis. Femur ORIF with intertrochanteric-subtrochanteric nailing was performed with no operative complications. Upon evaluation, patient disclosed more than twenty-year use of bisphosphonates for treatment of osteoporosis without cessation. Most recent DEXA scan revealed low bone mass (significant) in comparison to previous, with left femoral neck bone mineral density decreased by 12.3%. Due to significant functional decline from baseline of independent with ADLs and ambulation to moderate assistance, patient was admitted to an inpatient rehabilitation facility. At completion of her therapy program, pain had significantly decreased with minimal pain on exertion, and function improved to minimum to contact guard assist for ADLs, transfers, and ambulation.

Discussions: Bisphosphonates are used as first-line treatment option for osteoporosis in postmenopausal women due to its well-studied effects fragility fracture prevention. However, long term use defined as greater than three years of bisphosphonates is associated with an uncommon complication of atypical femoral fracture, accounting for 1.1% of all femoral fractures.

Conclusions: Bisphosphonates are effective in treating osteoporosis. However, prolonged use increases risk for development of atypical fractures. After three years of use, patients should undergo a drug holiday for wash-out and be reevaluated for restarting medication after risk benefit scrutinization.