Beyond stabilization: barriers and opportunities for sagittal alignment correction with transforaminal lumbar interbody fusion - a single tertiary center retrospective study.

BACKGROUND

Transforaminal lumbar interbody fusion (TLIF) is primarily performed for neural decompression and stabilization in degenerative lumbar disease. Although not intended as a deformity procedure, its biomechanical configuration permits incidental lordosis restoration. The extent of sagittal correction achievable through TLIF and the factors influencing it remain uncertain.

METHODS

We retrospectively analyzed 106 adult patients who underwent single- or multi-level TLIF between 2021 and 2024 at a tertiary academic center. Segmental and global lordosis corrections were measured using standing radiographs. Patient demographics, surgical approach (minimally invasive vs. open), cage type (fixed vs. expandable), cage angle, and cage subsidence were evaluated. Statistical analyses included Pearson's correlation, analysis of variance (ANOVA), t-tests, and effect size estimation.

RESULTS

Mean age was 63.1 ± 12.3 years; 49% were male. TLIF achieved consistent segmental correction across levels. Greater correction was observed in patients with worse baseline lordosis, particularly at L4-L5 (ρ = -0.524, p < 0.001) and L5-S1 (ρ = -0.510, p = 0.002). Segmental changes at L5-S1 (ρ = 0.575, p < 0.001) and L4-L5 (ρ = 0.263, p = 0.023) contributed most to global lordosis. Open TLIF achieved superior correction compared with minimally invasive surgery (MIS) (4.67° vs. 0.38°, p = 0.001). Fixed cages outperformed expandable cages, especially at L4-L5 (5.07° vs. 0.66°, p = 0.002), while cage angle did not correlate with alignment. Cage subsidence reduced correction at L3-L4 (p = 0.048) but had minimal global effect. Higher weight was associated with reduced global correction (ρ = -0.225, p = 0.027).

CONCLUSIONS

TLIF can meaningfully contribute to sagittal alignment, especially in patients with poor baseline lordosis. Open procedures and fixed cages provide superior correction, while MIS, expandable cages, subsidence, and higher patient weight limit outcomes. These findings highlight TLIF's underrecognized corrective potential and underscore the importance of tailoring surgical strategy to both patient and alignment goals.