Indirect Decompression Using the Keyhole Transfacet Full-Endoscopic Lumbar Interbody Fusion: Technical Note and Preliminary Clinical Application

BACKGROUND: Two widely used full-endoscopic lumbar interbody fusion (FE-LIF) techniques include the facet-preserving trans-Kambin approach, performed via a transforaminal corridor, and the facet-sacrificing endoscopic posterolateral transforaminal lumbar interbody fusion, which utilizes an interlaminar route. More recently, several authors have introduced an emerging transfacet endoscopic approach as an alternative, minimally invasive strategy for LIF. However, the majority of these studies have relied on direct decompression of neural elements, and the effectiveness of indirect decompression following transfacet endoscopic fusion has not yet been established. SURGICAL TECHNIQUE: This study describes a keyhole transfacet FE-LIF technique that employs indirect decompression to decompress neural elements. A limited facetectomy is performed using an endoscopic round burr to create a keyhole transfacet osseous corridor, allowing disc removal, endplate preparation, and interbody cage insertion without direct visualization or manipulation of the exiting or traversing nerve roots. When necessary, supplemental endoscopic direct decompression can be performed following cage placement in the same setting. CLINICAL APPLICATION: This study highlights the cases of 4 patients with diverse degenerative lumbar spine pathologies: low-grade degenerative spondylolisthesis, low-grade isthmic spondylolisthesis with severely collapsed disc space, segmental coronal lumbar deformity with severe spinal canal stenosis, and pseudarthrosis following prior lumbar interbody fusion surgery. All patients underwent keyhole transfacet FE-LIF with an indirect decompression technique and had a minimum follow-up of 1 year. CONCLUSION: This study describes the surgical technique for indirect decompression performed in a prone position using keyhole transfacet endoscopic fusion, presents early clinical application, and reports short-term radiographic observation associated with this technique. CLINICAL RELEVANCE: The keyhole transfacet endoscopic fusion offers a minimally invasive approach for achieving indirect decompression in the prone position in patients with various lumbar degenerative spinal conditions. In addition, adjunctive direct decompression can be performed in the same setting after cage insertion when indicated.