Preoperative Predictors of Intramedullary Increased Signal Intensity and Risk Factors for Poor Recovery in Thoracic Ossification of the Ligamentum Flavum: A Single-Center Retrospective Study

Study Design Retrospective cohort study. Objective To comprehensively evaluate the clinical and radiological characteristics across intramedullary increased signal intensity (ISI) grades (Grade 0, 1, and 2) on T2-weighted magnetic resonance imaging (MRI) and identify preoperative predictors of ISI severity as well as risk factors for poor postoperative recovery in patients with thoracic ossification of the ligamentum flavum (T-OLF). Methods A total of 148 patients who underwent posterior laminectomy surgery for T-OLF between January 2017 and August 2023 was retrospectively analyzed. Demographic, imaging, surgical, and clinical outcome data were collected. ISI grades were independently assessed by three blinded spinal surgeons. Univariate and multivariate logistic regression analyses were performed to identify independent predictors and risk factors. Results Higher ISI grades were associated with worse preoperative neurological status, greater spinal canal compression, more complex OLF morphology, and increased intraoperative blood loss. Multivariate analysis identified a high canal occupying ratio (COR) (Odds ratio [OR] = 3.20, P = .012) and beak-type configuration on sagittal MRI (OR = 4.24, P = .003) as independent predictors of higher ISI grades. Moreover, multi-segment OLF (OR = 2.23, P = .028) and ISI Grade 2 (OR = 3.67, P = .044) independently predicted poor postoperative recovery. Conclusion Preoperative ISI grade serves as a critical prognostic indicator in T-OLF. High COR and beak-type configuration on sagittal MRI predict severe ISI grades, whereas multi-segment OLF and ISI Grade 2 independently predict poor postoperative outcomes. Incorporating these parameters into preoperative assessment may improve risk stratification, patient counseling, and surgical planning.