Analysis of the combined CT findings improves the accuracy of CT for detecting posterior ligamentous complex injury of the thoracolumbar spine as defined by MRI

To determine the diagnostic accuracy of combined CT findings for detecting posterior ligamentous complex (PLC) injury in thoracolumbar fractures (TLFs) using MRI as a reference. A retrospective review of 263 consecutive patients with TLFs who underwent CT and MRI within ten days of injury. Two reviewers evaluated CT for the following findings: Facet joint malalignment (FJM), facet joint widening (FJW), horizontal laminar fracture (HLF), spinous process fracture (SPF), and interspinous widening (ISW). We examined the independent association of CT findings with PLC injury. Diagnostic accuracy of before combining CT findings to calculate the diagnostic accuracy [sensitivity, specificity, positive and negative predictive value (PPV, NPV), positive and negative likelihood ratio (+LR, -LR)]. PLC injury was defined by black stripe discontinuity due to supraspinous or ligamentum flavum rupture. FJM, SPF, HLF, and ISW were independently associated with PLC injury (aOR range 4.4-17.4). A single positive CT finding yielded a PPV of 31% and NPV of 66% for PLC injury. A negative CT for all the four findings had an NPV of 94% for PLC injury. ≥2 CT findings yielded a PPV of 91% for PLC injury. ≥2 CT findings provided the best combination to confirm PLC injury; thus, they can 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 four CT findings provided the highest sensitivity for PLC injuries.