Anterior Redisplacement After Intramedullary Nail Fixation for Trochanteric Femoral Fractures: Incidence and Risk Factors in 598 Older Patients.

Anterior redisplacement, defined as a postoperative anterior shift of the distal fragment despite intraoperative reduction, is occasionally observed after cephalomedullary nailing for trochanteric femoral fractures. However, its incidence and associated risk factors remain unclear. This study aimed to determine the incidence of anterior redisplacement following intramedullary nail fixation in geriatric trochanteric fractures, and to identify independent risk factors. This study retrospectively reviewed data from 598 consecutive hips in 577 patients (aged ≥65 years) who underwent intramedullary nail fixation for trochanteric fractures at a single center (2012-2023). Sagittal reduction on the lateral radiographic view was classified as posterior, anatomical, or anterior according to the position of the distal fragment, and was recorded preoperatively and postoperatively. Anterior redisplacement, the primary outcome, was defined as a change in alignment from a posterior or anatomical position postoperatively to an anterior position on any subsequent follow-up radiograph. Independent risk factors were identified by logistic regression. Among the 543 hips reduced posteriorly ( = 204) or anatomically ( = 339), anterior redisplacement occurred in 73 (13.4%). The incidence of anterior redisplacement was significantly higher following anatomical compared to posterior reduction (19.5% vs. 3.4%; < 0.001), and also higher in fractures that were anteriorly aligned preoperatively (18.0%) compared to anatomical (8.5%; < 0.01) and posterior (6.2%; < 0.01) alignment. Multivariate analysis revealed two independent predictors: preoperative anterior alignment (odds ratio [OR] 1.87, 95% confidence interval [CI] 1.24-2.81; = 0.003) and postoperative anatomical (vs. posterior) reduction (OR 6.49, 95% CI 2.92-14.44; < 0.001). Age, sex, Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association classification, Evans-Jensen classification, nail length, and canal-filling ratio were not associated with redisplacement. No lag-screw cutout occurred during the follow-up. Anterior redisplacement occurred in one of seven geriatric trochanteric fractures despite apparently satisfactory fixation. An anatomical sagittal reduction-traditionally considered "ideal"-increases the risk more than sixfold, whereas a deliberate posterior-buttress is protective. Unlike patient-related risk factors, sagittal reduction is under the surgeon's control. The study findings provide evidence that choosing a slight posterior bias can significantly improve stability.