Biportal Endoscopic Spinal Surgery for Posterior Decompression of Thoracic Myelopathy Caused by Single-level Thoracic Ossification of the Ligamentum Flavum.

Introduction: Thoracic ossification of the ligamentum flavum (T-OLF), which leads to neurological impairment, is a rare pathologic entity. Open posterior laminectomy is the gold standard treatment for T-OLF. However, the high rates of postoperative complications and perioperative morbidity have raised many concerns among surgeons. This study presented a series of patients with symptomatic single-level T-OLF who underwent posterior decompression using biportal endoscopic spinal surgery (BESS). The objective of this study was to demonstrate our procedure using BESS for T-OLF resection and to evaluate its safety and efficacy. Methods: We retrospectively reviewed patients who previously underwent thoracic posterior decompression with BESS between February 2021 and March 2023. Neurological status was assessed using the revised Japanese Orthopedic Association (JOA) score for thoracic myelopathy before surgery and at the final follow-up, along with the recovery rate (RR) at the final follow-up. The radiological outcome was evaluated by measuring the cross-sectional area (CSA) of the spinal canal from the T2 axial images at the most stenotic level, before and after surgery. Results: Twenty patients (8 male and 12 female; aged between 38 and 79 years) were enrolled in this study. The mean operation time was 89.7±21.8 min. The average JOA score was 5.6±1.1 before surgery and 9.1±1.0 at the final follow-up. The average RR at the final follow-up was 65.6%. Outcomes were classified as excellent in six patients (30.0%), good in nine patients (45.0%), and moderate in five patients (25.0%), with no cases categorized as fair or worsened (0%). The mean preoperative and postoperative CSA were 0.92±0.14 cm Conclusions: BESS is a safe, effective, and minimally invasive alternative to conventional open surgery for single-level T-OLF.