INTRODUCTION: Minimally invasive techniques, such as percutaneous endoscopic discectomy, are increasingly utilized for treating focal thoracic ossification of the ligamentum flavum (TOLF), where their safety and efficacy needs to be further confirmed. The purpose of this study was to investigate the safety and efficacy of percutaneous posterolateral transforaminal endoscopic surgery under local anesthesia for treating focal TOLF. METHODS: This case series study reviewed medical records of 12 cases diagnosed with focal TOLF who underwent percutaneous posterolateral transforaminal endoscopic surgery under local anesthesia from December 2016 to July 2019 at Fuzhou Second Hospital. Outcomes were functional status and complications. Functional status was evaluated by Epstein criteria and the Japanese Orthopedic Association score 1 d after surgery. The median follow-up time was 58.5 (47, 62) mo. RESULTS: Patients' median age was 65 (47, 70) y and 58.3% were female. The median surgical duration was 156 min and intraoperative blood loss was 10-30 mL. The Japanese Orthopedic Association score improved significantly from preoperatively to postoperatively (6 [5, 6] to 12.5 [12, 13], P <
0.001). Based on Epstein's criteria, treatment outcomes were excellent in nine cases, good in two cases, and fair in one case. All included patients returned to free movement from the second day after surgery. No severe complications were reported during follow-up. CONCLUSIONS: Percutaneous posterolateral transforaminal endoscopic surgery under local anesthesia can achieve satisfactory safety and efficacy for treating TOLF. No severe complication was noticed during long-term follow-up.