Radiographic analysis of neuroforaminal and central canal decompression following lateral lumbar interbody fusion.

Background: Lateral lumbar interbody fusion (LLIF) is a minimally invasive surgical option for treating symptomatic degenerative lumbar spinal stenosis (DLSS) in select patients. However, the efficacy of LLIF for indirectly decompressing the lumbar spine in DLSS, as well as the best radiographic metrics for evaluating such changes, are incompletely understood. Methods: A single-institutional cohort of patients who underwent LLIF for DLSS between 5/2015 - 12/2019 was retrospectively reviewed. Diameter, area, and stenosis grades were measured for the central canal (CC) and neural foramina (NF) at each LLIF level based on preoperative and postoperative T2-weighted MRI. Baseline facet joint (FJ) space, degree of FJ osteoarthritis, presence of spondylolisthesis, interbody graft position, and posterior disc height were analyzed as potential predictors of radiographic outcomes. Changes to all metrics after LLIF were analyzed and compared across lumbar levels. Preoperative and intraoperative predictors of decompression were then assessed using multivariate linear regression. Results: A total of 102 patients comprising 153 fused levels were analyzed. Pairwise linear regression of stenosis grade to diameter and area revealed significant correlations for both the CC and NF. All metrics except CC area were significantly improved after LLIF ( Conclusions: Radiographically, LLIF is effective at indirect compression of the CC and NF at all lumbar levels, though worse FJ osteoarthritis predicted higher degrees of post-operative stenosis.