Analysis of the Combined Computed Tomography Findings Improves the Accuracy of Computed Tomography for Detecting Posterior Ligamentous Complex Injury of the Thoracolumbar Spine as Defined by Magnetic Resonance Imaging

Abstract

Objective: To determine the diagnostic accuracy of combined computed tomography (CT) findings for detecting posterior ligamentous complex (PLC) injury in thoracolumbar fractures using magnetic resonance imaging as a reference. Methods: A retrospective review of 263 consecutive patients with thoracolumbar fractures who underwent CT and magnetic resonance imaging within 10 days of injury. Two reviewers evaluated CT for the following findings: facet joint malalignment, facet joint widening, horizontal laminar fracture, spinous process fracture, and interspinous widening. We examined the independent association of CT findings with PLC injury before combining the CT findings to calculate the diagnostic accuracy: sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), and positive and negative likelihood ratios. PLC injury was defined by black stripe discontinuity caused by supraspinous or ligamentum flavum rupture. Results: Facet joint malalignment, spinous process fracture, horizontal laminar fracture, and interspinous widening were independently associated with PLC injury (adjusted odds ratio range, 4.4e17.4). A single positive CT finding yielded a PPV of 31% and NPV of 66% for PLC injury. Two or more CT findings yielded a PPV of 91% for PLC injury. A negative CT for all the 4 CT sings had a 94% NPV for PLC injury. Conclusions: Two or more CT findings provided the best combination to confirm PLC injury; thus, this combination could be used as a criterion for injured PLC. A single CT finding lacks sufficient predictive value to confirm or rule out PLC injury. A negative CT for the 4 CT findings provided the highest sensitivity for PLC injuries.