Variables Associated With Lag Screw Sliding After Single-Screw Cephalomedullary Nail Fixation of Intertrochanteric Fractures

OBJECTIVES: To evaluate variables associated with lag screw sliding after single-screw cephalomedullary nail (CMN) fixation of intertrochanteric femur fractures. DESIGN: Retrospective cohort study. SETTING: Level-one trauma center. PATIENTS/PARTICIPANTS: 158 intertrochanteric fractures in patients older than 65 years with an average follow-up of 22 months. INTERVENTION: Single-screw CMN fixation. MAIN OUTCOME MEASUREMENTS: Lag screw sliding and revision surgeries. RESULTS: The average amount of lag screw sliding was 5+/-5 mm (range, 0 to 21 mm). Lag screw sliding was greater with unstable fracture patterns (mean difference (MD) 2 mm, 95% confidence interval (CI) 0.4 to 3.5 mm, p=0.01) and calcar gapping > 4 mm (MD 3.7 mm, 95% CI 2 to 5 mm, p 0.05). Revision surgeries were performed in 6 (4%) patients. Indications included symptomatic lag screw removal (n=2), avascular necrosis (n=1), cutout (n=1), loss of reduction (n=1), and perimplant fracture (n=1). CONCLUSIONS: Unstable fracture patterns are unavoidable, however, careful attention to calcar reduction and selection of dual-screw CMN implants may minimize lag screw sliding and its detrimental effects on outcomes. LEVEL OF EVIDENCE: Level III, Retrospective cohort study.