Evaluation of Diagnostic Accuracy of Magnetic Resonance Imaging in Posterior Ligamentum Complex Injury of Thoracolumbar Spine

Abstract

Study Design: Prospective diagnostic imaging study. Purpose: The stability of the thoracic and lumbar spine depends significantly on the posterior ligamentum complex (PLC). Therefore, it is essential to diagnose PLC injuries accurately before deciding on a treatment plan for thoracolumbar injury patients. However, the efficacy of magnetic resonance imaging (MRI) in diagnosing PLC remains undetermined. Overview of Literature: MRI has become the ultimate tool in diagnosing spine injury cases, as previous literature suggests that it has very high sensitivity and specificity. But this is still controversial and as many surgeons rely on just MRI for selecting the patient for surgery, it becomes important to know the diagnostic accuracy of it. Methods: Patients who sustained injuries from T1 to L3 and required posterior surgery were prospectively studied. The treating surgeon and musculoskeletal radiologist participating in the study reviewed preoperative MRI images to characterize the level(s) of injury and the integrity of the six components of the PLC. These were classified as intact, incompletely disrupted, or disrupted. During the surgical procedure, the surgeon also classified each component of the PLC, and the radiologist’s and surgeon’s findings were compared. Results: Out of 66 patients, 46 were males (69.7%) and 20 were females (30.3%), and the average age was 34.12 years. According to the kappa score, there was a moderate level of agreement between the radiologist’s interpretation and the intraoperative findings for all PLC components except for the thoracolumbar fascia and ligamentum flavum for which there was a slight agreement. The sensitivity for the intact PLC components ranged from 100% (supraspinous ligament) to 66.67% (ligamentum flavum). The specificity ranged from 100% (interspinous ligament) to 52% (thoracolumbar fascia). The Spearman’s rank correlation ranged from 0.061 for the thoracolumbar fascia to 0.918 for the interspinous ligament, and the percentage agreement ranged from 81.82% (interspinous ligament to 36.36% (thoracolumbar fascia). Conclusions: The sensitivity and specificity of MRI for diagnosing injury of the PLC in this study were lower than those previously reported in the literature. The integrity of the PLC as determined by MRI should not be used in isolation to determine treatment.