Long-term Bisphosphonate Therapy-induced Periprosthetic Femoral Stress Fracture in a Sliding Hip Screw Implant: A Unique Case Report

INTRODUCTION Long-term bisphosphonate therapy for osteoporosis is associated with an increased risk of low-to-no energy atypical subtrochanteric and femoral shaft fractures with characteristic radiologic findings. There are few reports of patients with long-term bisphosphonate-induced periprosthetic fractures, all of them had a hip arthroplasty prosthesis. In this report, we present a unique case of a 90-year-old Caucasian female on long-term bisphosphonate therapy with a sliding hip screw implant who sustained a periprosthetic fracture of the femoral shaft at the distal aspect of the plate. CASE REPORT In April 2014, a 90-year-old female presented with left thigh pain after a fall from standing height. She had a previous fixation of a left intertrochanteric hip fracture with a sliding hip screw in 1999 and a 9-year history of bisphosphonate therapy. Radiographs obtained in the emergency department revealed a left-sided femoral shaft fracture at the distal aspect of the previously applied five-hole side plate. Of note, the periprosthetic fracture demonstrated cortical thickening at the fracture site of the lateral femoral cortex, lack of comminution as well as a transverse appearance. The patient was taken to the operating room the next day for retrograde placement of an intramedullary nail of the left femur with revision of left intertrochanteric femur fracture fixation. By 3 months postoperatively, she had obtained full radiographic union. CONCLUSION This case report highlights the possibility of an atypical fracture distal to the sliding hip screw implant after open reduction internal fixation of an intertrochanteric hip fracture in patients on long-term bisphosphonates.