The clinical efficacy of unilateral biportal endoscopic treatment for lumbar spinal stenosis with preservation of the ligamentum flavum: a comparative retrospective study

As a minimally invasive surgical approach for treating lumbar spinal stenosis, Unilateral Biportal Endoscopy (UBE) is receiving significant attention from clinical practitioners. Conventional UBE surgery involves the removal of the ligamentum flavum, and to date, there is no research on UBE techniques that preserve the ligamentum flavum. A retrospective analysis was conducted on 100 patients with lumbar spinal stenosis (LSS) who underwent UBE treatment from January 2022 to March 2024. The surgical techniques of decompression of the lumbar canal while preserving the ligamentum flavum using UBE technology were summarized. Patients were divided into two groups based on whether the ligamentum flavum was preserved during surgery: the preservation group with 40 patients, and the removal group with 60 patients. The intraoperative surgical time and blood loss of the two groups were compared, as well as perioperative Visual Analogue Pain Scores (VAS), Oswestry Disability Index (ODI), and complications such as dural tears and epidural hematoma. The difference in radiological decompression between the two groups was assessed using the cross-sectional area of the dural sac on lumbar MRI. The ligamentum flavum preservation group had significantly shorter surgical time (mean difference: -16.34 min, P < 0.01) and less blood loss (mean difference: -28.13 ml, P < 0.01) compared to the ligamentum flavum removal group. There was no difference in the VAS scores and ODI scores between the two groups at 3 days and 6 months postoperatively. The postoperative dural sac cross-sectional area was 164.31 ± 26.35 mm² in the preservation group and 170.92 ± 27.68 mm² in the removal group, with no statistically significant difference between groups (mean difference: -6.61 mm², 95% CI: [-17.75 to 4.53], P = 0.24). Although this difference was not statistically significant, the similar absolute values suggest that both techniques achieved a comparable and substantial degree of radiological decompression. The incidence of postoperative complications was 1.92% in the ligamentum flavum preserved group and 5.77% in the ligamentum flavum removed group, which was not statistically significant (P = 0.61). In this retrospective study, UBE with ligamentum flavum preservation was associated with reduced operative time and blood loss, with comparable clinical outcomes. Further prospective studies are warranted to confirm these findings.