Unilateral biportal endoscopy versus percutaneous endoscopic lumbar discectomy for far lateral disc herniation: a comparative study of clinical efficacy and learning curves

PURPOSE: To compare the clinical outcomes and learning curves of unilateral biportal endoscopy (UBE) and percutaneous endoscopic lumbar discectomy (PELD) in the treatment of far lateral lumbar disc herniation (FLLDH). METHODS: A retrospective analysis was conducted on 122 patients with FLLDH who underwent spinal endoscopic surgery between January 2022 and July 2024, including 62 cases in the PELD group and 60 cases in the UBE group. All procedures were performed by the same minimally invasive spine surgery team. Perioperative parameters (operative time, intraoperative blood loss, foraminal area, postoperative hospital stay, total cost), visual analogue scale (VAS) scores, Oswestry Disability Index (ODI), and modified Macnab criteria were compared. Learning curves were analyzed using cumulative sum (CUSUM) with operative time as the core variable. All patients were followed for at least 12 months. RESULTS: Both groups achieved significant improvement in pain and functional outcomes after surgery. Operative time was significantly longer in the UBE group than in the PELD group (132.77 ± 27.55 min vs. 86.61 ± 24.52 min), and total blood loss was also higher (270.43 ± 119.44 ml vs. 37.32 ± 13.69 ml). The PELD group showed lower postoperative day-1 back pain scores, whereas long-term VAS, ODI, and modified Macnab outcomes were comparable between groups. The excellent/good rates were 91.9% in the PELD group and 93.3% in the UBE group. CUSUM analysis demonstrated learning curve inflection points at 24 cases for UBE and 38 cases for PELD. CONCLUSION: Both UBE and PELD are safe and effective for treating FLLDH. PELD offers advantages in perioperative minimally invasive characteristics and cost-efficacy, whereas UBE features a shorter learning curve, facilitating more rapid surgical mastery.