Is Biportal Endoscopic Laminectomy Equivalent to Microscopic Laminectomy in Patients With Lumbar Spinal Stenosis? A Multicenter, Assessor-blind, Randomized Clinical Trial

Abstract

Background: Lumbar spinal stenosis (LSS) impairs quality of life and is commonly treated with microscopic laminectomy. Some have suggested that biportal endoscopic laminectomy may offer advantages through smaller incisions and reduced tissue trauma. However, it remains unclear whether these theoretical advantages translate into meaningful differences in patient-reported outcomes that patients would actually perceive.

Questions/purposes: We performed an RCT in which we asked: (1) Does biportal endoscopic laminectomy result in equivalent functional outcomes as measured by the Oswestry Disability Index (ODI) at 1 year compared with microscopic laminectomy? (2) Are pain relief, quality of life measures, and surgery-related outcomes similar between biportal endoscopic laminectomy and microscopic laminectomy? (3) Are adverse event rates comparable between the two surgical techniques?

Methods: We conducted an assessor-blind RCT at six centers in South Korea. Between July 19, 2021, and April 6, 2023, a total of 120 patients with LSS were randomized to undergo biportal endoscopic laminectomy (n = 60) or microscopic laminectomy (n = 60). At 1 year, 90% (54 of 60) of patients in the biportal endoscopic laminectomy group and 86.7% (52 of 60) of patients in the microscopic laminectomy group were accounted for and fully analyzed. No crossover occurred between treatment groups, and the primary analysis followed a modified intention-to-treat approach. The baseline characteristics were well balanced between the two groups. The primary outcome was the ODI score at 12 months postoperatively. Secondary outcomes included VAS pain scores, quality of life, perioperative parameters, and adverse events, assessed at baseline, 2 weeks, and at 3, 6, and 12 months. This was an equivalence trial using the ODI as the primary outcome for sample size calculation, with an equivalence margin of ± 12.8 points, which represents the minimum clinically important difference for the ODI.

Results: In the modified intention-to-treat analysis, we found no difference between the biportal endoscopic laminectomy and microscopic laminectomy groups in terms of ODI scores at 12 months (13 ± 12 versus 18 ± 18, mean difference -5 points [95% confidence interval -10 to 1]; p = 0.12), demonstrating equivalence between the techniques. Secondary outcomes including VAS pain scores, quality of life measures, functional recovery, satisfaction, surgical variables, and radiographic parameters were also similar between groups, with no clinically important differences observed. Adverse events were similar between biportal endoscopic laminectomy and microscopic laminectomy.

Conclusion: This study found biportal endoscopic laminectomy to be equivalent to microscopic laminectomy in functional outcomes at 12 months. However, the observed differences do not represent clinically meaningful benefits that patients would perceive. Until high-quality evidence demonstrates patient-important advantages, we recommend against the wide adoption of this technique in clinical practice.

Level of evidence: Level I, therapeutic study.