Oblique Lateral Interbody Fusion With Lateral Vertebral Screw Fixation Versus Transforaminal Lumbar Interbody Fusion for Severe Lumbar Stenosis: Results of a Multicenter Randomized Controlled Trial

BACKGROUND AND OBJECTIVES: The benefits of oblique lateral interbody fusion (OLIF) vs transforaminal lumbar interbody fusion (TLIF) in severe lumbar stenosis (Schizas C/D) remain uncertain. This randomized trial compared clinical, radiographic, and safety outcomes of OLIF and TLIF. METHODS: From November 2018 to December 2021, a prospective, multicenter, randomized controlled trial enrolled 260 adults with single-level severe stenosis and instability. In total, 224 patients were randomized to OLIF or TLIF. Prespecified outcomes followed consolidated standards of reporting trials. Primary outcomes were visual analog scale back/leg pain and Oswestry Disability Index (ODI), with minimal clinically important difference thresholds of ODI ≥12-13 points or ≥30% improvement, and visual analog scale ≥1.5-2.0 points. Radiographic measures included disc height, lumbar and segmental lordosis, and canal cross-sectional area (CSA). Complications were recorded. Ethics approval was obtained from the institutional review board, the trial was registered with ISRCTN.com , and all patients provided written informed consent. RESULTS: In total, 224 patients were randomized, 5 were lost to follow-up (TLIF n = 2, OLIF n = 3). Baseline features were comparable. OLIF was associated with shorter operative time, less blood loss, earlier ambulation, and shorter hospital stay (all P < .05). Both groups achieved significant, clinically meaningful improvements. OLIF showed greater back pain reduction at 3-6 months and 2 years ( P < .05) and superior ODI improvement at 3 and 6 months ( P < .001), although long-term ODI scores were similar. Radiographically, OLIF provided greater restoration of disc height and segmental lordosis (all P < .001) and demonstrated progressive CSA increase (dynamic decompression), whereas TLIF achieved immediate, sustained CSA enlargement. Fusion rates were comparable at 1-2 years. Complication rates were low and similar (7.3% TLIF vs 5.5% OLIF), with most OLIF-specific events transient. CONCLUSION: Both OLIF and TLIF yield improvements in severe lumbar stenosis. OLIF offers perioperative advantages, earlier functional recovery, radiographic restoration, and dynamic canal remodeling, supporting its role as an equivalent alternative for lumbar spinal stenosis with some secondary advantages.