Ligamentum flavum preservation via unilateral biportal endoscopy in lumbar discectomy: a "Door-Opening" technique and its clinical outcomes.

Abstract

To describe a novel "ligamentum flavum (LF) door-opening" technique under unilateral biportal endoscopy (UBE) and evaluate its clinical efficacy, particularly in preserving LF integrity and reducing postoperative epidural fibrosis, compared to conventional partial LF resection in lumbar disc herniation (LDH). A retrospective analysis was conducted on 102 patients with single-level LDH who underwent UBE surgery (Jan 2022-Jun 2024). Patients were divided into the Complete Ligamentum Flavum Preservation (C-LFP) group (n = 50) using the new technique and the Partial Ligamentum Flavum Resection (P-LFR) group (n = 52). Perioperative parameters, Visual Analog Scale (VAS) for back/leg pain, Oswestry Disability Index (ODI), and epidural fibrosis were compared. All surgeries were successful, with no significant differences in operative time, blood loss, or hospital stay. Both groups showed comparable improvements in leg pain and ODI at all follow-ups. The C-LFP group showed statistically lower back pain VAS scores at 6-month and final follow-up (P < 0.05), although this difference did not reach the minimal clinically important difference. At 6-month MRI, the C-LFP group had significantly lower epidural fibrosis grade and incidence: 62.0% (31/50) had Grade 0 fibrosis versus 26.9% (14/52) in the P-LFR group (p < 0.05), with no high-grade (III/IV) fibrosis in the C-LFP group. The UBE-assisted "LF door-opening" technique is safe and effective for lumbar disc herniation. It preserves the anatomical barrier function of the ligamentum flavum and significantly reduces postoperative epidural fibrosis compared with conventional partial resection.