Time-Dependent Revision Risk and Failure Modes After Total Hip Arthroplasty and Hemiarthroplasty for Displaced Femoral Neck Fracture in Patients Younger Than 70 Years: A Multicenter Analysis of 1,176 Consecutive Cases.

Abstract

Although total hip arthroplasty (THA) and hemiarthroplasty (HA) are widely used for femoral neck fractures (FNFs) in younger adults, outcome data in this population are limited. We analyzed revision risks, failure patterns, and clinical outcomes of THA or HA in FNF patients younger than 70 years across eight institutions. We analyzed 1,176 patients (645 THAs; 531 HAs; mean follow-up, 6.1 years). The primary outcome was the cumulative incidence of revision and the time point at which the cumulative incidence diverged. The secondary outcomes included revision incidence by age subgroup, risk factors for revision, modes of failure, mortality, surgical complications, 30-day readmissions, and emergency department visits. In overall and subgroup analyses, the cumulative incidence of revision did not differ between THA and HA, but from 5.5 years, the curves diverged in favor of THA. Comorbidity was independently associated with revision, whereas age and procedure were not associated. In THA, dislocation was the most common mode of failure (66.7%), predominantly within one year. In HA, periprosthetic joint infection (PJI; 44.4%) predominated within one year, whereas periprosthetic femoral fracture (PFF; 27.8%) and acetabular erosion (16.7%) were the leading failure modes after five years. The THA group showed lower mortality (P < 0.001), PJI (P = 0.002), and postoperative PFF (P = 0.006) rates and higher dislocation rates (P = 0.001). The 30-day readmission and emergency department visits were similar. The revision rates did not differ between THA and HA at a mean follow-up of 6.1 years. However, from 5.5 years postoperatively, cumulative revision incidence diverged in favor of THA, reflecting late HA revisions due to PFF and acetabular erosion. Revision risk was associated with patient comorbidity. Preventing early dislocation (THA) and PJI (HA) may improve outcomes; HA warrants closer surveillance after five years owing to a late rise in revision risk.