Clinical effect of UBE-ULBD en bloc resection of ligamentum flavum in the treatment of lumbar spinal stenosis

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Objective To evaluate the clinical efficacy, radiographic outcomes, and safety of unilateral biportal endoscopic unilateral laminotomy for bilateral decompression (UBE-ULBD) with en bloc ligamentum flavum resection for lumbar spinal stenosis (LSS), and to identify a safe, efficient surgical method that observed complications. Materials and methods This study included 178 patients who underwent UBE-ULBD across 263 spinal levels between January 2022 and December 2024. Inclusion criteria were radiographically confirmed LSS, failure of conservative treatment for at least three months, and Schizas grade B to D stenosis. Clinical outcomes were assessed using the Oswestry Disability Index (ODI) and the Visual Analog Scale (VAS) for back and leg pain. Radiological parameters, including dural sac cross-sectional area (CSDA) and facet joint preservation rate, were measured on MRI using ImageJ software. Statistical analyses were performed using the Wilcoxon signed-rank test and paired t -test. Results Postoperatively, VAS scores for back pain and leg pain decreased significantly from 6.36 ± 1.64 and 6.55 ± 1.71 to 1.96 ± 0.69 and 2.17 ± 0.87, respectively ( P < 0.001). The ODI improved from 65.50 ± 6.49 to 26.68 ± 4.99 ( P < 0.001). CSDA increased markedly from 54.41 ± 21.44 mm 2 to 164.23 ± 46.52 mm 2 ( P < 0.001). Postoperatively, the ipsilateral inferior articular process width decreased from 9.06 ± 2.09 mm to 5.57 ± 2.25 mm, whereas the contralateral width decreased from 9.12 ± 2.18 mm to 8.18 ± 2.23 mm. The ipsilateral and contralateral facet joint preservation rates were 60.03% ± 16.45% and 89.32% ± 9.16%, respectively. Complications included five cases (2.8%) of asymptomatic dural tears, all of which healed uneventfully without sequelae; no patient required revision surgery. Conclusions UBE-ULBD with en bloc ligamentum flavum resection significantly improved short-term clinical and radiographic outcomes in LSS patients, with favorable facet preservation and low complications. However, comparative studies with extended follow-up are needed. This technique appears a safe, effective minimally invasive option for selected patients.