Risk Factors for Poor Outcomes of Thoracic Ossification of Ligamentum Flavum After Laminectomy

BACKGROUND: Thoracic ossification of ligamentum flavum (TOLF) is a common pathological change of the thoracic ligamentum flavum. Identifying the risk factors for poor prognosis is critical for choosing suitable surgical methods. MATERIAL/METHODS: A total of 64 patients with TOLF after laminectomy were reviewed between January 2010 and April 2018 at the Department of Spine Surgery of the Third Hospital of Hebei Medical University. The Japanese Orthopaedic Association (JOA) scale was used to evaluate the neurological function of patients. According to the average JOA improvement rate, the patients were divided into the good prognosis group (Group GP) and the poor prognosis group (Group PP). Multivariate logistic regression analysis was used to identify the risk factors for poor outcomes. RESULTS: The average JOA improvement rate was 53.04±24.29%. Group GP comprised 33 patients, while Group PP comprised 31 patients. Duration of preoperative symptoms (P=0.005), intramedullary high signal intensity (P=0.001), dural ossification rate (P=0.002), and sagittal configuration of ossification (P=0.012) were significantly higher in Group PP than in Group GP. Multivariate logistic analysis showed that duration of preoperative symptoms (P=0.022), intramedullary high signal intensity (P=0.010), dural ossification (P=0.007) and sagittal configuration of ossification (P=0.029) were risk factors for poor outcomes of TOLF after laminectomy. CONCLUSIONS: After surgical treatment of TOLF, the symptoms of some patients either recovered slowly or did not recover. Longer than 17 months of preoperative symptoms, intramedullary high signal intensity, dural ossification, and sagittal configuration of ossification were the risk factors for poor outcomes of TOLF after laminectomy.