Predictors of Clinical Outcome After Endoscopic Partial Facetectomy for Degenerative Lumbar Foraminal Stenosis

Endoscopic partial facetectomy (EPF) is an effective option for decompressing the lumbar exiting root without causing spinal instabilities in the treatment of patients with degenerative lumbar foraminal stenosis. The aim of the present study was to identify the preoperative risk factors of poor clinical outcomes after EPF in patients with degenerative lumbar foraminal stenosis. A total of 51 consecutive patients who had undergone EPF from 2012 to 2015 were included in the present study. The clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry disability index (ODI), and Short-Form 36-item (SF-36) outcome questionnaires. The preoperative radiological risk factors were measured using the lumbar Cobb's angle, disc wedging angle, lumbar lordosis (LL), segmental lordosis, disc height index, presence of spondylolisthesis, and morphological changes (no change, horizontal collapse, vertical collapse) of the exiting root within the most stenotic level on preoperative magnetic resonance imaging. The VAS, ODI, and SF-36 scores had significantly improved at the 1-month follow-up visit compared with the baseline mean values and were maintained within the 2-year follow-up period. A correlation analysis revealed significant relationships between various preoperative factors and clinical outcomes. On multiple regression analysis, the morphological change of vertical collapse significantly predicted the VAS, ODI, and SF-36 scores, and LL significantly predicted the ODI and SF-36 scores. A morphological change in vertical collapse found on preoperative magnetic resonance imaging and decreased LL were significant predictors of poor clinical outcomes after EPF in the treatment of lumbar foraminal stenosis.