Incidence and Risk Period of Periprosthetic Femoral Fracture After Cementless Bipolar Hemiarthroplasty in Elderly Patients

Background: The purpose of this study was to investigate the periprosthetic femoral fracture (PFF) after cementless bipolar hemiarthroplasty incidence, noting fracture types and the results of treatment in elderly patients. Methods: We retrospectively reviewed 1563 elderly patients (1177 women and 386 men) who underwent cementless bipolar hemiarthroplasty for femoral neck fracture (1061 patients) or intertrochanteric fracture (502 patients). The type of fracture was classified according to the Vancouver classification. The average age was 79.6 years (range, 65-103 years). Clinical and radiologic evaluations were performed and Kaplan-Meier survivorship was analyzed. Results: Thirty-seven PFFs (2.4%) occurred during a mean follow-up of 44.4 months. Two-thirds of PFFs (67%) occurred within 1 year. Most PFFs (22/27), which occurred within 2 years, were Vancouver type B fractures. After that, type A fractures were predominant (7/9). Based on Kaplan-Meier survivorship with PFF as the end point, the incidence rate was 1.7% (95% confidence interval [CI] = 1.6%-1.8%) at 12 months, 2.2% (95% CI = 2.1%-2.3%) at 36 months, and 3.8 % (95% CI = 3.6%-4.0%) at 144 months postoperatively. Conclusion: After cementless bipolar hemiarthroplasty in elderly patients, a caution should be paid to prevent PFF particularly during 1-year postoperatively.