Independent Risk Factors for Lag Screw Cut-Out: The Role of Open Reduction in Intertrochanteric Fracture Fixation With the Proximal Femoral Nail.

BACKGROUND Intertrochanteric femoral fractures are common in older adults, and proximal femoral nail (PFN) fixation is widely preferred due to its biomechanical advantages. Lag screw cut-out, defined as the progressive migration of the lag screw through the femoral head with loss of fixation, is one of the most serious mechanical complications after PFN fixation. This complication can result in mechanical failure and require revision surgery. Therefore, this study aimed to identify independent risk factors for lag screw cut-out and evaluate lag screw stability in patients without cut-out. MATERIAL AND METHODS We retrospectively reviewed 302 patients treated with PFN between January 2023 and December 2024; 190 met the inclusion criteria. Patients were grouped by fracture stability and surgical approach. Demographic, clinical, and radiographic parameters (tip-apex distance [TAD], calcar TAD, collodiaphyseal angle, Cleveland index, lag screw advancement) were analyzed. Logistic regression identified predictors of cut-out, while sequential radiographs evaluated positional changes in non-cut-out cases. RESULTS Cut-out occurred in 30 patients (15.8%). Unstable fractures and open reduction were independent risk factors for cut-out, while age, sex, TAD, calcar TAD, Cleveland index, and collodiaphyseal angle showed no significant association. In non-cut-out cases, TAD, calcar TAD, and collodiaphyseal angle remained stable, with a mean lag screw advancement of 0.4 cm. CONCLUSIONS Unstable fractures and open surgery independently increase the risk of lag screw cut-out after PFN fixation. In contrast, non-cut-out cases showed radiographic stability, supporting the importance of accurate reduction and proper implant positioning for long-term reliability.