[Early effectiveness of posterior 180-degree decompression via unilateral biportal endoscopy in treatment of lumbar spinal stenosis combined with MSU-1 lumbar disc herniation].

Objective: To evaluate early effectiveness of posterior 180-degree decompression via unilateral biportal endoscopy (UBE) in the treatment of lumbar spinal stenosis (LSS) combined with Michigan State University (MSU)-1 lumbar disc herniation (LDH).

Methods: A retrospective analysis was conducted on clinical data from 33 patients with LSS combined with MSU-1 LDH, who met selection criteria and were treated between March 2022 and January 2024. All patients underwent UBE-assisted 180-degree spinal canal decompression. The cohort comprised 17 males and 16 females, aged 37-82 years (mean, 67.1 years). Preoperative presentations included bilateral lower limbs intermittent claudication and radiating pain, with disease duration ranging from 5 to 13 months (mean, 8.5 months). Affected segments included L _{3, 4} in 4 cases, L _{4, 5} in 28 cases, and L ₅, S ₁ in 1 case. LSS was rated as Schizas grade A in 4 cases, grade B in 5 cases, grade C in 13 cases, and grade D in 11 cases. LDH was categorized as MSU-1A in 24 cases, MSU-1B in 2 cases, and MSU-1AB in 7 cases. Intraoperative parameters (operation time, blood loss) and postoperative hospitalization length were recorded. The visual analogue scale (VAS) score and Oswestry Disability Index (ODI) were used to assess the lower limb pain and functional outcomes after operation. Clinical efficacy was evaluated at last follow-up via modified MacNab criteria. Quantitative radiological assessments included dural sac cross-sectional area (DSCA) measurements and spinal stenosis grading on lumbar MRI. Morphological classification of lumbar canal stenosis was determined according to the Schizas grading, categorized into four grades.

Results: The operation time was 60.4-90.8 minutes (mean, 80.3 minutes) and intraoperative blood loss was 13-47 mL (mean, 29.9 mL). The postoperative hospitalization length was 3-5 days (mean, 3.8 days). All patients were followed up 12-16 months (mean, 13.8 months). The VAS score and ODI improved at immediate and 3, 6, and 12 months after operation compared to before operation, and the differences between different time points were significant ( P<0.05). At last follow-up, the clinical efficacy assessed by the modified MacNab criteria were graded as excellent in 23 cases, good in 9 cases, and poor in 1 case, with an excellent and good rate of 96.97%. Postoperative lumbar MRI revealed the significant decompression of the dural sac in 32 cases, with 1 case showing inadequate dural expansion. DSCA measurements confirmed progressive enlargement and stenosis reduction over time. The differences were significant ( P<0.05) before operation, immediately after operation, and at 6 months after operation. At 6 months after operation, Schizas grading of spinal stenosis improved to grade A in 27 cases and grade B in 6 cases.

Conclusion: Posterior 180-degree decompression via UBE is a safe and feasible strategy for treating LSS combined with MSU-1 LDH, achieving effective neural decompression while preserving intervertebral disc integrity.