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: We retrospectively reviewed the records at two level 1 trauma centers for patients who presented with supracondylar femur fractures (AO/OTA 33A, C) and were treated with locking plate fixation between 1/1/2004 and 1/1/2011. 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 (AP) and lateral views. Images were analyzed independently by three 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 four months postoperatively), when compared to 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 four months postoperatively is an accurate and reliable predictor of final healing outcome following 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.
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