MIS-TLIF vs Open TLIF in Combined Lumbar Stenosis and Low-grade Spondylolisthesis

Study Design. An open-label, randomized, non-inferiority clinical trial Objective. To determine the effectiveness of the MIS-TLIF over the O-TLIF in patients with symptomatic lumbar stenosis combined with low-grade spondylolisthesis by comparing the clinical efficacy and safety. Summary of Background Data. In patients with combined lumbar spinal stenosis and spondylolisthesis, it remains uncertain whether minimally invasive fusion surgery is non-inferior to the open approach. Methods. We conducted an open-label, non-inferiority trial involving patients with symptomatic lumbar stenosis combined with low-grade spondylolisthesis. Patients were randomly assigned in a 1:1 ratio to undergo either MIS-TLIF or open TLIF surgery. The primary endpoint was the reduction in the Oswestry Disability Index (ODI) score from baseline to 3 months post-surgery, with a non-inferiority margin of 12 points. Secondary outcomes included 3-month changes from baseline in back and leg pain, neuropathic pain, satisfaction with treatment, intraoperative data, and cost-effectiveness. Results. In the modified intention-to-treat population, the mean difference was 0.4, with the corresponding 90% confidence interval of (−5.7 to 6..5) having a lower bound below the non-inferiority margin of 12. Similar results were obtained by analysis of the per-protocol population. 82.8% of patients achieved the MCID for the ODI. Results for secondary outcomes (clinical scales, complications) showed no significant differences between the treatment groups (all P >0.05). Although the open TLIF group had a hospital stay that was 1.5 day days longer ( P =0.005) and required additional analgesia more frequently ( P =0.026), direct costs were 10.5% higher in the MIS-TLIF group ( P <0.001). Conclusions. This is the first high-quality study comparing open TLIF and MIS-TLIF with a validated primary endpoint. Among patients with combined lumbar degenerative stenosis and degenerative spondylolisthesis, MIS-TLIF resulted in clinical outcomes at 3 months that were non-inferior to those with open TLIF.