Single-Skin-Incision Dual-level Unilateral Biportal Endoscopy Decompression for Lumbar Canal Stenosis Using Independent Fascial Corridors: A Technical Note

Unilateral biportal endoscopy (UBE) has become an established minimally invasive technique for lumbar canal stenosis, offering excellent visualization and bilateral decompression while minimizing soft-tissue disruption. Adjacent two-level decompression, however, conventionally requires multiple portal pairs or portal redirection techniques that may increase surgical access or compromise ergonomics. We describe a novel single-skin-incision dual-level UBE decompression using independent fascial corridors, which preserves optimal working trajectories while eliminating the need for an additional cranial portal. A 46-year-old woman presented with a 12-year history of progressive neurogenic claudication and severe back and leg pain refractory to conservative treatment. Magnetic resonance imaging demonstrated severe L4–L5 and L5–S1 central canal, lateral recess, and foraminal stenosis without dynamic instability. Right-sided UBE decompression was performed using two skin incisions. Following standard decompression at L4–L5, the endoscope and instruments were withdrawn, and new fascial openings were created through the same skin incisions to establish independent working and viewing corridors for L5–S1 decompression. This allowed target-specific docking and conventional decompression at both levels without additional portals or specialized instrumentation. The patient was mobilized on the day of surgery with immediate improvement in neurogenic claudication. At 36 h postoperatively, the Visual Analog Scale improved from 7 to 4 for back pain and from 8 to 2 for leg pain, with no new neurological deficits. This technical modification demonstrates the feasibility of decoupling the skin incision from the fascial trajectory to achieve adjacent two-level lumbar decompression through common cutaneous portals while maintaining independent working corridors. The technique exploits favorable geometric planning and lumbar lordosis to preserve instrument triangulation and ergonomic access without prolonged subfascial tunnelling or additional portals. Although larger studies are required to establish its clinical advantages, this simple modification may further reduce the surgical footprint of multilevel UBE decompression while preserving standard operative principles.