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

Background: Although adequate intraoperative imaging is routinely performed during cephalomedullary nailing for trochanteric femoral fractures, an anterior shift of the distal fragment—referred to as anterior redisplacement—is occasionally observed postoperatively. However, the incidence of this dynamic malalignment and its underlying mechanisms remain unclear. Methods: 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 both 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. Results: Among the 543 hips reduced posteriorly (n = 204) or anatomically (n = 339), anterior redisplacement occurred in 73 (13.4%). The incidence of anterior redisplacement was significantly higher following anatomical than posterior reduction (19.5% vs 3.4%; p <0.001) and also higher in fractures that were anteriorly aligned preoperatively (18.0%) than in anatomical (8.5%; p <0.01) and posterior (6.2%; p <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; p = 0.003) and postoperative anatomical (vs posterior) reduction (OR 6.49, 95% CI 2.92–14.44; p <0.001). Age, sex, Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association classification, Jensen classification, nail length, and canal-filling ratio were not associated with redisplacement. No lag-screw cutout occurred during the follow-up. Conclusions: 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.