Biportal Endoscopic Techniques for Severe Dural Ossification in Thoracic Ossification of the Ligamentum Flavum: Insights From Preoperative Imaging

Objective: This study evaluates surgical strategies based on preoperative computed tomography (CT) findings during unilateral biportal endoscopic (UBE) surgery for thoracic ossification of the ligamentum flavum (OLF) with dural ossification.Methods: This retrospective study included patients undergoing posterior thoracic laminectomy via UBE surgery to treat symptomatic thoracic stenosis due to OLF. Clinical outcomes were assessed using visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) scores, alongside analyses of preoperative CT and intraoperative videos for dural ossification characteristics.Results: A total of 34 patients participated, showing significant improvements in VAS and JOA scores postoperatively. All focal dural ossifications exhibiting the tram-track sign were effectively excised without significant dural defects. The circumferential floating technique was employed for cases with the bridge sign, whereas wide excision was warranted for those with the comma sign.Conclusion: UBE surgery effectively manages progressive thoracic OLF associated with dural ossification. Preoperative CT imaging is essential for assessing dural involvement and guiding surgical techniques. Microscopic surgery is recommended for inexperienced surgeons requiring wide dural excision.