MIS-TLIF Versus Open TLIF in Combined Lumbar Stenosis and Low-Grade Spondylolisthesis

STUDY DESIGN: An open-label, randomized, noninferiority 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 noninferior to the open approach. MATERIALS AND METHODS: We conducted an open-label, noninferiority 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 three months postsurgery, with a noninferiority margin of 12 points. Secondary outcomes included three-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% CI of -5.7 to 6.5, having a lower bound below the noninferiority 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 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