“One and a Half” Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF): A Single-Center Retrospective Case Series

Introduction: Spondylolisthesis with multilevel stenosis is traditionally treated with open decompression and multilevel fusion, which can lead to adjacent segment degeneration and postoperative complications. Our recent biomechanical study demonstrated that minimally invasive (MI) tubular decompression causes less instability than open laminectomy at the adjacent level of MI-TLIF. This prompted us to adopt the "One and a Half TLIF" approach, combining MIS fusion at the unstable segment with unilateral laminotomy for bilateral decompression of adjacent stenosis. This study evaluates reoperation rates, specifically fusion extension to adjacent levels, alongside clinical outcomes in pain and disability, radiological results, and complications, with a minimum follow-up of one year.

Methods: This retrospective case series examined patients who underwent "One and a Half TLIF" by a single surgeon from 2015 to January 2023. Radiological outcomes were assessed using X-rays and sagittal CT scans. Pseudarthrosis was defined as the absence of bony bridging lucency with ≥2 degrees angulation changes or ≥1 mm translation in flexion-extension X-rays and subsidence as >2 mm loss in intervertebral height from post-op to follow-up. Clinical outcomes were measured via NRS and ODI scores. Wilcoxon Signed Rank Test and paired t-test were computed in R Studio, with significance set at 0.05.

Results: Thirty-three patients underwent the procedure, with median clinical and radiological follow-ups of 26.88 and 12 months, respectively. The reoperation rate was 6.1%, with two patients requiring fusion extension. Median NRS-L improved from 5.5 preoperatively to 0 at follow-up (p = 0.022), and ODI improved from 38 to 13.5 (p = 0.008). Radiographically, anterior and posterior disc height and foraminal height increased significantly. The subsidence rate was 19.2%, and the fusion rate was 96.2%.

Conclusion : The "One and a Half TLIF" approach demonstrates promising results for managing spondylolisthesis with multilevel stenosis. It significantly improves pain and disability while reducing the risks associated with traditional multilevel fusion.