Technical Factors Contributing to Nonunion in Supracondylar Distal Femur Fractures Treated With Lateral Locked Plating: A Risk-Stratified Analysis

Abstract Objective: To identify technical factors associated with nonunion after operative treatment with lateral locked plating. Design: Retrospective cohort study. Setting: Ten Level 1 trauma centers. Participants: Six hundred fifteen adult patients with supracondylar distal femur fractures (OTA/AO Type 33A or C). Intervention: Lateral locked plating. Main Outcome Measurements: Surgery for nonunion. Results: We observed nonunion rates of 2% in a low-risk of nonunion group (n = 129), 4% in a medium-risk group (n = 333), and 14% in a high-risk group (n = 153). Varus malreduction with an anatomic lateral distal femoral angle (aLDFA) greater than 84 degrees, was associated with double the odds of nonunion (OR, 2.1; 95% CI, 1.1 to 4.2; P = 0.03). Malreduction by medial translation of the articular block increased the odds of nonunion, with 30% increased odds per 4 mm of medial translation (95% CI, 1.0 to 1.6; P = 0.03). Working length increased the odds of nonunion primarily in the medium risk group, with an 18% increase in nonunion per 10 mm increase in working length (95% CI, 1.0 to 1.4; P = 0.01). Proximal screw density was protective against nonunion (OR, 0.71; 95% CI, 0.53 to 0.92; P = 0.02). Lateral plate length and type of plate material were not associated with nonunion. Conclusions: Malreduction is a surgeon-controlled variable associated with nonunion after lateral locked plating of supracondylar distal femur fractures. Longer working lengths were associated with nonunion, suggesting that simple bridge plating may be less likely to succeed for longer fractures. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.