Mid-to-Long Term Radiological and Clinical Outcomes of Oblique Lateral Interbody Fusion versus Posterior Lumbar Interbody Fusion for Severe Lumbar Spinal Stenosis: A Retrospective Comparative Study

Purpose: To explore and compare the clinical efficacy and radiological changes of oblique lateral interbody fusion (OLIF) and posterior lumbar interbody fusion (PLIF) in patients with severe lumbar spinal stenosis (LSS). Patients and Methods: We retrospectively collected data from 34 patients with severe LSS (Schizas grade C or D) who underwent either OLIF or PLIF at our institution between June 2014 and June 2020. Imaging evaluation included the cross-sectional area (CSA) of the spinal canal and ligamentum flavum on MRI. Clinical evaluation included Visual Analogue Scale (VAS) scores and Oswestry Disability Index (ODI). Statistical analysis was performed using independent sample t -tests and analysis of variance for repeated measures. Results: The cross-sectional area of the spinal canal in the OLIF group was gradually expanded from 47.6 ± 16.5 mm 2 preoperatively to 67.0 ± 17.8 mm 2 at 3 weeks and further to 97.5 ± 22.3 mm 2 at 1 year (P < 0.05), while the area of ligamentum flavum was decreased from 119.9 ± 49.7 mm 2 to 107.0 ± 38.9 mm 2 and to 87.8 ± 25.3 mm 2 , respectively (P < 0.05). At 3 weeks after the operation, the improvement of VAS score (Low back: 1.3 vs 3.8; Leg: 1.6 vs 3.6) and ODI (12.24 vs 35.21) of low back and leg pain in the PLIF group was better than that in the OLIF group (P < 0.05). There was no significant difference in VAS score and ODI between the two groups 1 year after operation (P > 0.05). Conclusion: OLIF technology provides significant mid-term (1-year) spinal canal dilatation and clinical improvement in severe LSS, achieving outcomes comparable to PLIF. Therefore, OLIF can be considered a viable and effective surgical option for severe LSS. Keywords: oblique lateral interbody fusion, indirect decompression, lumbar spinal stenosis, MRI, clinical features