Comparison of 2-Year Postoperative Clinical Outcomes between Transforaminal and Lateral Transpsoas Lumbar Interbody Fusion in the Treatment of Degenerative Spondylolisthesis at L4-5

Background: Lumbar interbody fusion has been shown to be effective in the treatment of degenerative spondylolisthesis, though a variety of surgical techniques exist and there are few direct comparisons between homogenous patient samples in the literature to guide evidence-based decision making. This is a retrospective review of prospectively collected data from a multi-center, patient outcomes registry. The purpose of this study is to compare perioperative and two-year postoperative clinical outcomes between patients treated with either lateral Lumbar Interbody Fusion (LLIF) using real-time, directional neuromonitoring or Transforaminal Lumbar Interbody Fusion (TLIF) for isolated degenerative spondylolisthesis at L4-5. Methods: A total of 72 patients (47 LLIF, 25 TLIF) who underwent single-level interbody fusion at L4-5 for degenerative spondylolisthesis with a minimum of two year postoperative clinical outcomes were included in the analysis. Results: The baseline characteristics were similar across the groups (all, p>0.05). Postoperative length of hospital stay was similar between groups (p>0.05), however, operative time was lower in the LLIF group compared to the TLIF group (119.2 minutes vs. 149.7 minutes, respectively; p=0.053). Complications were more frequent in the TLIF group compared to the LLIF group (p=0.057), with a notable absence of neurological injuries in both groups. MCID thresholds were met in 74%, 84% and 72% of LLIF patients and 72%, 63% and 75% of TLIF patients for Oswestry Disability Index (ODI), lower back pain and worst-leg pain, respectively. Similarly, Substantial Clinical Benefit (SCB) was met in 76% to 84% of LLIF patients and 67% to 81% of TLIF patients (all p>0.05). Conclusion: In the treatment of degenerative spondylolisthesis at L4-5, both LLIF, with real-time neural monitoring and TLIF resulted in substantial clinical improvements that were maintained through two years postoperative, though with more complications and generally depressed clinical outcomes in the TLIF group compared to the LLIF group