Comparing Efficacy and Outcomes Between ALIF and TLIF at the L5-S1 Level in Over 1,000 Patients Using the Michigan Spine Surgery Improvement Collaborative (MSSIC) Database

Introduction: With the development of different approaches to the spine, our ability to treat spine deformity with the use of interbody cages for fusion has revolutionized how we care for spine patients. While different approaches may suit specific indications and are dependent on surgeon expertise and familiarity, there is a paucity of studies investigating the head-to-head benefits of different approaches at specific levels of the spine. In this study we sought to compare the efficacy, safety, and outcomes of ALIF vs. TLIF at the L5-S1 level for treating various spinal pathologies.

Methods: We reviewed 4400 patients who underwent single level fusion surgery across the multi-institutional cohort of MSSIC participant sites from January 2017 to December 2022. Patient demographic information and surgical characteristics, including clinical presentation were tabulated. Patient reported outcomes (PROs) were reported using the QOL, PROMIS and EQ5D surveys to assess improvement in symptoms and function.

Results: A total of 423 single-level ALIF cases and 721 TLIF cases at the L5-S1 level were reviewed. Overall 57% of patients in the ALIF sub-group were female, compared to 50% in the TLIF sub-group (p < 0.001). ALIF patients had on average lower BMI (30.1 vs 32.0, p< 0.001). Patients who underwent TLIF had a higher proportion of neurogenic claudication at baseline (12.1% vs 7.3%, p=0.01). Across all PRO metrics assessed, there were no significant statistical differences in either baseline, 90-day post op, 1-year postop, or 2-year postop when comparing ALIF vs TLIF in this patient cohort. The largest improvement for both techniques was seen in PROMIS MCID, where both ALIF and TLIF sub-groups demonstrated a 10% increase in number of patients achieving MCID at both 1-year and 2-year postoperatively.

Conclusion : Different surgical approaches can be used for specific surgical indications, however ultimately ALIF and TLIF at L5-S1 yield similar results when assessing PROs at 1- and 2-years postoperatively.