Early (<3 months) versus late (≥3 months) periprosthetic femoral fractures after hip arthroplasty: fracture characteristics and treatment patterns

Background To describe and compare injury context, fracture morphology, bone stock, and treatment patterns between periprosthetic femoral fractures (PFFs) occurring <3 months and ≥3 months after index hip arthroplasty using a prespecified operational timing threshold. Methods We retrospectively reviewed consecutive patients hospitalized for their first documented PFF episode after total hip arthroplasty or hemiarthroplasty at a tertiary orthopedic referral hospital from January 2021 through December 2025. Early PFF was defined as <3 months and late PFF as ≥3 months using a prespecified primary operational cutoff based on the month-level interval from index arthroplasty to PFF. Between-group comparisons used Wilcoxon rank-sum tests, Fisher exact tests, and standardized mean differences (SMDs). P values were interpreted descriptively, and absolute percentage-point differences with 95% confidence intervals (CIs) were reported for selected binary contrasts. A 6-month cutoff was examined post hoc as a sensitivity analysis. Results Among 132 patients, 126 had a usable month-based interval; 23 (18.3%) had early PFF and 103 (81.7%) had late PFF. Low-energy injury was recorded in 23/23 (100.0%) early PFFs and 86/102 (84.3%) late PFFs, corresponding to an absolute difference of 15.7 percentage points (95% CI, 0.2–24.0). Vancouver B2/B3 fractures occurred in 8/23 (34.8%) versus 22/102 (21.6%) patients (absolute difference, 13.2 percentage points; 95% CI, −5.1–34.7). Surgery was performed in 21/23 (91.3%) versus 88/103 (85.4%), and ORIF was the most frequent treatment in both groups. At the 6-month cutoff, multiple fracture categories and treatment strategies remained represented in both timing groups. Conclusions In this cohort, a 3-month operational grouping suggested a difference in recorded injury context, while both timing groups included multiple fracture morphologies, bone-stock categories, and treatment strategies. Timing may provide useful contextual information at presentation but should be interpreted together with Vancouver classification, implant stability, bone stock, and patient condition. These observations require validation in larger cohorts with finer timing resolution.