Comparison of Uniportal and Biportal Endoscopic Unilateral Laminotomy for Bilateral Decompression Based on Three Decompression Boundaries in Degenerative Lumbar Stenosis: A Retrospective Analysis of Clinical and Radiographic Outcomes

Background The decompression effects and facet joint preservation are inconsistent between uniportal endoscopic unilateral laminectomy for bilateral decompression (UE-ULBD) and biportal endoscopic unilateral laminectomy for bilateral decompression (BE-ULBD). Besides the methods themselves, are there other factors involved? This study evaluated the clinical and radiological outcomes of these two techniques in patients with degenerative lumbar spinal stenosis while strictly adhering to the established boundaries of endoscopic decompression. Methods This retrospective analysis involved 69 patients, with 34 undergoing UE-ULBD and 35 receiving BE-ULBD, all followed for a minimum of 6 months postoperatively. Three decompression boundaries were strictly adhered to during procedures. Patient outcomes were assessed using the Visual Analog Scale (VAS), the Oswestry Disability Index (ODI), and operative time, while radiological outcomes measured the dural sac cross-sectional area, multifidus muscle area, medial facet angles, and the diameters of facet joints/articular surfaces. Results Both groups experienced significant improvements in ODI and VAS. The BE-ULBD group had a shorter operative time (76.2 ± 12.1 vs 64.5 ± 10.1 min, P  < 0.0001), while the UE-ULBD group had less multifidus muscle swelling (15.41 ± 7.20 vs. 111.3 ± 26.08 mm², P  < 0.05). No statistically significant differences were found between the groups regarding dural sac expansion (90.29 ± 16.07 mm² vs. 92.83 ± 11.93 mm², P  = 0.459), increments in the bilateral facet joint medial angles (ipsilateral: 40.82 ± 4.41° vs. 41.47 ± 4.19°, P  = 0.529; contralateral: 16.96 ± 6.81° vs. 18.18 ± 5.05°, P  = 0.401), or the extent of facet joint width resection (ipsilateral: 1.98 ± 1.02 mm vs. 1.87 ± 1.01 mm, P  = 0.678; contralateral: 2.02 ± 1.07 mm vs. 2.07 ± 0.66 mm, P  = 0.833) and articular surface width (ipsilateral: 2.17 ± 1.06 mm vs. 2.64 ± 1.01 mm, P  = 0.061; contralateral: 1.38 ± 0.64 mm vs. 1.41 ± 0.77 mm, P  = 0.838) ( P  > 0.05). Conclusion Under strict adherence to the decompression boundaries, both techniques achieved equivalent radiological decompression effects in the spinal canal and similar facet resection rates, resulting in favorable clinical outcomes. BE-ULBD demonstrated superior surgical efficiency, while UE-ULBD minimized paraspinal tissue trauma.