Radiologic and Clinical Evaluation of Posterolateral Versus Transforaminal Interbody Fusion in Degenerative Lumbar Spondylolisthesis.

Abstract

Retrospective cohort study. The primary objective is to compare foraminal height (FH) and disk height (DH) differences in posterolateral (PLF) and transforaminal interbody fusions (TLIFs) and secondarily correlate these measurements with patient-reported outcomes. The impact FH has on patient outcomes in degenerative lumbar spinal fusion surgery is unknown. Postoperative FH change and how it relates to patient-reported outcomes in posteriorly based procedures has not been well evaluated. A retrospective review of a subset of patients from a prospective cohort from the Canadian Spine Outcomes and Research Network was undertaken. Radiographic assessment preoperatively, at 3 months and 1 year, with standing lumbar spine radiographs were completed. FH and DH were recorded at each time interval, differences between groups were compared, and correlations with patient-reported outcomes were assessed. One hundred nine patients were included (23 PLF and 86 TLIF). At 3-month follow-up, the change in FH was greater in the TLIF group (mean difference =2.3; 95% CI: 0.8-3.5, P=0.002). The change in FH remained significantly different at 12 months (mean difference=1.6, 95% CI: 0.2, 3.0mm, P=0.028). The change in DH was greater in the TLIF group, with a mean difference between groups of 4.1mm (95% CI: 2.5, 5.7, P<0.001) and 3.6mm (95% CI: 2.0, 5.3, P<0.001). A positive change in FH correlated with less back pain, less disability, and improved physical function in the TLIF group (P<0.05). Patients treated with PLF lost FH over time. An increased difference in FH at 1 year was associated with improved function and less back pain in the TLIF group.