Lower lumbar lordosis (LLL) plays a critical role in maintaining spinal balance, and degeneration at the L4-S1 segment frequently contributes to adjacent segment degeneration (ASD) after lumbar interbody fusion. Currently, the main surgical approaches for treating lumbar degenerative disease fall into two categories: posterior techniques represented by transforaminal lumbar interbody fusion (TLIF), and anterior techniques, represented by anterior lumbar interbody fusion (ALIF). Posterior approaches, such as TLIF, are more commonly used but are often constrained by their operative space, cage size, and orientation, which can result in kyphosis. In contrast, ALIF allows for the cutting of the anterior longitudinal ligament and the removal of nearly the entire intervertebral disc enabling the insertion of a larger and more lordotic cage. To date, no research has compared ALIF and TLIF in the treatment of L4-S1 degenerative disc disease and the impact on sagittal parameters as well as the occurrence of ASD during follow-up. This study aims to evaluate and compare the efficacy of anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF) in restoring L4-S1 lordosis and its impact on the development of ASD.
We conducted a retrospective case review for the patients who underwent L4-S1 fusion surgery for degenerative lumbar disease between January 2017 and January 2022 at a single institution. Patients were categorized into TLIF and ALIF groups. The preoperative, 1-month postoperative, and final follow-up radiographic images were collected and analyzed independently by 2 authors to assess pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), PI-LL, L4-S1 lordosis, L3/4 disc angle, and L1-L3 lordosis. Demographic data, perioperative complications, surgical data, and reoperation data were also reported in this study. Statistical analyses employed Pearson’s χ2 test, independent samples t-test, repeated measures ANOVA test with Bonferroni correction, and multivariate logistic regression to determine outcomes.
A total of 153 patients were analyzed (103 TLIF and 50 ALIF). Both groups exhibited significant changes in lordosis; however, ALIF resulted in a more pronounced increase in L4-S1 lordosis and reduced compensatory changes at L3/4 compared with TLIF. The TLIF group had a significantly higher reoperation rate (25.2% vs. 8.0%, p = 0.017) and greater intraoperative blood loss (423.6 mL vs. 249.4 mL, p = 0.002). Multivariate analysis identified post-operative L4-S1 lordosis and changes in L4-S1 lordosis (delta L4-S1) as protective factors against the incidence of ASD.
ALIF demonstrated superior effectiveness compared to TLIF in restoring and maintaining L4-S1 lordosis, mitigating compensatory curvature, and decreasing the incidence of ASD. Although TLIF offered a shorter operative time, it was associated with increased blood loss and higher reoperation rates. The enhanced preservation of spinal alignment with ALIF makes it the preferred surgical approach for treating L4-S1 degenerative disc disease.