Neurological and Functional Outcomes After Decompression With or Without Fusion for Thoracic Ossification of the Ligamentum Flavum: A Systematic Review and Evidence Synthesis

Abstract

Thoracic ossification of the ligamentum flavum (TOLF) is an important cause of thoracic myelopathy. This systematic review evaluated neurological and functional outcomes after posterior decompression with or without fusion for TOLF and assessed perioperative safety. An electronic search of PubMed/MEDLINE was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Studies published up to December 2024 that reported adult patients undergoing posterior decompression with or without fusion for TOLF were included. Neurological recovery was assessed using the modified Japanese Orthopaedic Association score and recovery rate. Perioperative outcomes included cerebrospinal fluid leakage, blood loss, infection, and operative time. Owing to clinical and methodological heterogeneity, a narrative synthesis was performed using the Synthesis Without Meta-analysis framework. Risk of bias was assessed using ROBINS-I, and the certainty of evidence was evaluated using the GRADE approach. Ten retrospective cohort studies including 846 patients were included. Regarding the primary neurological outcomes and perioperative safety, the use of an ultrasonic osteotome reduced operative time, blood loss, and dural tear rates compared with a high-speed burr, without significant differences in long-term neurological outcomes. Dural ossification was the strongest predictor of cerebrospinal fluid leakage. Regarding secondary prognostic factors, longer symptom duration, preoperative intramedullary T2 hyperintensity, and lower baseline modified Japanese Orthopaedic Association scores were associated with poorer neurological recovery. Furthermore, a signal change ratio ≥1.54 on quantitative magnetic resonance imaging and sagittal beak-type ossification were associated with unfavorable prognosis. Overall certainty of evidence was low to very low. Outcomes after surgery for TOLF are primarily determined by preoperative neurological status and magnetic resonance imaging features. These findings may help guide surgical timing and selective fusion, while operative technique appears to mainly influence perioperative safety.