Biomechanical Evaluation of Lumbar Decompression Adjacent to Instrumented Segments. Issue 6 (December 2016)

• Record Type: Journal Article
• Authors: Grunert, Peter; Reyes, Phillip M.; Newcomb, Anna G.U.S.; Towne, Sara B.; Kelly, Brian P.; Theodore, Nicholas; Härtl, Roger
• Is Part Of: Neurosurgery. Volume 79:Issue 6(2016)
• Publication Date: 2016-12
• Subjects: Biomechanics -- Lumbar fusion -- MIS decompression -- Spine -- Spine degeneration; Nervous system -- Surgery -- Periodicals; 617.48005
• DOI: 10.1227/NEU.0000000000001419
• Languages: English
• ISSNs: 0148-396X

Abstract

Abstract : BACKGROUND: Multilevel lumbar stenosis, in which 1 level requires stabilization due to spondylolisthesis, is routinely treated with multilevel open laminectomy and fusion. We hypothesized that a minimally invasive (MI) decompression is biomechanically superior to open laminectomy and may allow decompression of the level adjacent the spondylolisthesis without additional fusion. OBJECTIVE: To study the mechanical effect of various decompression procedures adjacent to instrumented segments in cadaver lumbar spines. METHODS: Conditions tested were (1) L4-L5 instrumentation, (2) L3-L4 MI decompression, (3) addition of partial facetectomy at L3-L4, and (4) addition of laminectomy at L3-L4. Flexibility tests were performed for range of motion (ROM) analysis by applying nonconstraining, pure moment loading during flexion-extension, lateral bending, and axial rotation. Compression flexion tests were performed for motion distribution analysis. RESULTS: After instrumentation, MI decompression increased flexion-extension ROM at L3-L4 by 13% ( P = .03) and axial rotation by 23% ( P = .003). Partial facetectomy further increased axial rotation by 15% ( P = .03). After laminectomy, flexion-extension ROM further increased by 12% ( P = .05), a 38% increase from baseline, and axial rotation by 17% ( P = .02), a 58% increase from baseline. MI decompression yielded no significant increase in segmental contribution of motion at L3-L4, in contrast to partial facetectomy and laminectomy (<.05). CONCLUSION: MI tubular decompression is biomechanically superior to open laminectomy adjacent to instrumented segments. These results lend support to the concept that in patients in whom a multilevel MI decompression is performed, the fusion might be limited to the segments with actual instability. ABBREVIATION: MI, minimally invasive Abstract : Supplemental Digital Content is Available in the Text.