271 Endoscopic Laminectomy Effectively Treats Grade 1 Spondylolisthesis Without Leading to Progression of Radiographic Instability

INTRODUCTION: Lumbar stenosis with grade 1 spondylolisthesis can be treated with decompression with or without fusion, while fusion providing better quality-of-life metrics and reduced re-operation rates. Patients with larger amounts of anterolisthesis are thought to be at higher risk of progression with decompression alone rather than decompression and fusion. Endoscopic interlaminar laminectomy is an ultra-minimally invasive approach that preserves the posterior tension band and has less muscle disruption than traditional minimally invasive tubular decompressions. METHODS: All patients who underwent endoscopic interlaminar lumbar stenosis with spondylolisthesis at a large tertiary academic center were reviewed. To exclude trivial spondylolistheses, inclusion criteria were a minimal of 5mm of slip and existing pre-operative and post-operative flexion/extension lumbar x-rays for review of stability. Clinical and radiographic measures were assessed. RESULTS: Twenty-four patients underwent endoscopic interlaminar laminectomy for spondylolisthesis during the study period. Of these, 4 patients met inclusion criteria. Three patients were elective for neurogenic claudication and discharged home from PACU, and 1 was emergent for worsening cauda equina symptoms who was discharged home after 3 days. All had clinical improvement. Average age was 77.3, BMI was 27.6, EBL of 8.7mL, and surgical length of 167min. The degree of anterolistheis did not change in extension (8.00 ± 0.82 pre-op vs 8.03 ± 0.92 post-op, p = 0.89) nor in flexion (8.55 pre-op ± 0.66 vs 8.9 ± 0.91, p = 0.26). All patients were treated at L4-5 and no patients underwent re-operation with an average follow up time of 8.1 ± 0.7 months. CONCLUSIONS: Endoscopic interlaminar laminectomy is an effective treatment for lumbar stenosis with grade 1 spondylolisthesis >5mm without notable risk of progression of radiographic instability.