The influence of ossification morphology on surgery outcomes in patients with thoracic ossification of ligamentum flavum (TOLF)

BACKGROUND: To determine whether there is a correlation between the type of ossification and radiological parameters, modified thoracic JOA scores, and complications in patients with thoracic ossification of ligamentum flavum treated by posterior thoracic surgery. METHODS: This retrospective cohort study included 48 patients with thoracic myelopathy caused by single-level thoracic ossification of ligamentum flavum who underwent thoracic posterior approach surgery in our Hospital o between December 2013 to December 2018. Patients were divided into unilateral, bilateral, and bridged groups in axial position, and beak and round groups in sagittal position. The differences were analyzed according to the ossification morphology. RESULTS: In axial myelopathy, there was no significant difference in preop and postop JOA scores and RR among the three groups in axial position (P = 0.884). In sagittal view, there was no significant difference in preoperative JOA score between the two groups (P = 0.710), while the postop JOA score and the recovery rate in the beak group were significantly lower than that of the round group (P = 0.010, P = 0.034). Two-way ANOVA showed that sagittal morphology had a significant effect on postop JOA score (P = 0.028), but axial morphology don’t (P = 0.431); there was no interaction between them (P = 0.444). For the recovery rate, sagittal morphology also had a significant effect (P = 0.043), but axial ossification don’t (P = 0.998); there was no interaction between them (P = 0.479). CONCLUSION: Sagittal morphology had a significant adverse effect on postop JOA score and surgical outcome, while axial morphology had no effect on surgical outcome, and there was no interaction between sagittal morphology and axial morphology.