Standalone Anterior Lumbar Interbody Fusion for Spondylolisthesis

Abstract

Introduction Debate continues over the optimal approach for fusion of isthmic and degenerative spondylolisthesis. We favor anterior lumbar interbody fusion (ALIF) as it permits liberal discectomy and placement of a large, lordotic device which restores disc height and sagittal balance, reduces listhesis, and indirectly decompresses exiting nerve roots. There are only a few articles in the literature looking at the degree of reduction and the durability over time in patients undergoing ALIF with spondylolisthesis. Material and Methods We studied the initial degree of reduction achieved, and the durability of this reduction over time when ALIF was used for patients with isthmic and degenerative spondylolisthesis. Analysis of prospectively collected radiographic data was conducted. All patients with lumbar spondylolisthesis who underwent standalone ALIF between 2009 and 2013 by a single surgeon (R. J. M.) were included. Radiological analysis of slip percentage and disc height on preoperative, postoperative, and latest follow-up imaging was performed with Surgimap Spine software. Demographic factors, surgical data and radiological results were compared. Results Average patient age was 64.5 years (range, 37–84) with 16 females, 15 males. There were 36 levels treated with 20 at L4/5, 15 at L5/S1, and one at L3/4. Mean listhesis was 16% which immediately postoperatively reduced to 2.3%, but at latest follow-up had recurred to 58% of the original value. An average disc height increase of 184% was observed postoperatively. Analysis of these measurements showed a high degree of inter- and intraclass correlation. Mean follow-up was 17 months. BMI correlated with immediate postoperative reduction ( p = 0.004), as did posterior disc height ( p = 0.04). The overall radiological fusion rate was 91%. Three patients required subsequent posterior instrumentation, which will be discussed. Conclusion ALIF achieves disc height restoration and indirect listhesis reduction in isthmic and degenerative spondylolisthesis. Although this reduction may regress over time, we found it remained reduced by approximately 50% at latest follow-up. Around 10% of patients required further strengthening by posterior pedicle screw fixation. Standalone ALIF without posterior pedicle screw fixation is successful in the majority of patients with spondylolisthesis.