Any Cortical Bridging Predicts Healing of Supracondylar Femur Fractures After Treatment With Locked Plating.

OBJECTIVES:To determine the accuracy and reliability of radiographic cortical bridging criteria in predicting the final healing of supracondylar femur fractures after treatment with locked plating. DESIGN:Retrospective review. SETTING:Two Level 1 trauma centers. PATIENTS/PARTICIPANTS:Patients who presented with supracondylar femur fractures (OTA/AO 33A, C) and were treated with locking plate fixation between January 1, 2004, and January 1, 2011. The final study population included 82 fractures after excluding patients with open physes (n = 4), nondisplaced fractures (n = 4), early revision for technical failure (n = 4), or inadequate follow-up (n = 42). INTERVENTION:Distal femur locking plate fixation. MAIN OUTCOME MEASUREMENTS:Postoperative radiographs until final follow-up were assessed for cortical bridging at each cortex on anterior-posterior and lateral views. Images were analyzed independently by 3 orthopaedic traumatologists to allow for assessment of reliability. Final determination of union required both radiographic and clinical confirmation. RESULTS:Assessment for any cortical bridging was the earliest accurate predictor of final union (95.1% accuracy at 4 months postoperatively), compared with criteria requiring bicortical bridging (93.9% accuracy at 6 months) and tricortical bridging (78% accuracy at 21 months). Any cortical bridging demonstrated a higher interobserver reliability (kappa = 0.73) relative to bicortical (kappa = 0.27) or tricortical bridging (kappa = 0.5). CONCLUSIONS:Our results for plate fixation of supracondylar distal femur fractures mirror those previously described for intramedullary nailing of tibia shaft fractures. Any radiographic cortical bridging by 4 months postoperatively is an accurate and reliable predictor of final healing outcome after locking plate fixation of supracondylar femur fractures. Assessment for bicortical or tricortical bridging is less reliable and inaccurate during the first postoperative year. LEVEL OF EVIDENCE:Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.