Multicenter External Validation of the Accuracy of Computed Tomography Criteria for Detecting Thoracolumbar Posterior Ligamentous Complex Injury

Abstract

BACKGROUND AND OBJECTIVE: Recent studies have proposed computed tomography (CT) criteria for posterior ligamentous complex (PLC) injury: disrupted if ≥2 CT findings, indeterminate if single finding, and intact if 0 CT findings. The study aims to validate the CT criteria for PLC injury externally. METHODS: Three level 1 trauma centers enrolled 614 consecutive patients with acute thoracolumbar fractures (T1-L5) who received CT and MRI. Three reviewers from each center assessed CT for facet joint malalignment, horizontal laminar fracture, spinous process fracture, and interspinous widening and MRI for disrupted PLC, defined as black stripe discontinuity. The primary outcome is the diagnostic accuracy of CT criteria (0, 1, ≥2 findings) in detecting disrupted PLC on MRI using all CT readings. A subgroup analysis was performed for each participating center and reviewer. The inter-reader agreement on PLC status on MRI and CT criteria was assessed using Fleiss Kappa (k). RESULTS: The positive predictive value for PLC injury was 0 findings 3%, single positive CT 43%, and ≥2 CT findings in 94%. The accuracy measures were consistent across various centers and reviewers. The area under the curve for ≥1 CT finding in detecting PLC injury ranged from 90% to 97%, indicating excellent discrimination for all centers. The inter-reader k on PLC status by MRI and overall CT findings was substantial (k > 0.60). CONCLUSION: This study externally validates the previously proposed CT criteria for PLC injury. A total of ≥2 positive CT findings or 0 CT findings can be used as criteria for a disrupted PLC (B-type injury) or intact PLC (A-type injuries), respectively, without added MRI. A single CT finding implies indeterminate PLC status and the need for further MRI assessment. The CT criteria will potentially guide MRI indications and treatment decisions for neurologically intact thoracolumbar burst fractures.