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.