Early Nontraumatic Periprosthetic Femoral Fracture After Total Hip Arthroplasty: A Case Report.

This report describes a rare case of early nontraumatic periprosthetic femoral fracture following total hip arthroplasty. The patient was a 74-year-old woman with osteoarthritis of the hip who underwent left total hip arthroplasty via a posterior approach using a tapered, rectangular, cementless femoral stem. The patient progressed well through early rehabilitation and was ambulating independently by postoperative Day 8. However, on postoperative Day 9, she experienced sudden-onset thigh pain and was unable to bear weight while ascending stairs. Radiographs demonstrated a short oblique fracture of the left femur that was located distal to the stem tip and classified as a Vancouver type C (postoperative) fracture. Open reduction and internal fixation were performed using a locking plate in conjunction with cables and screws. At the 2-year follow-up, the patient had regained her ability to ambulate independently, and radiographs confirmed successful bone union. Finite element analysis suggested that concentration of stress around the tip of the stem as a result of flexed stem alignment, together with stair climbing, may have contributed to the periprosthetic femoral fracture. Caution is warranted when inserting a femoral stem in a flexed position because of an increased risk of periprosthetic femoral fracture.