One-Level versus Two-Level Anterior Lumbar Interbody Fusion (ALIF) from L4-S1: Comparison of Complications, Alignment, and Patient Outcomes.

ABSTRACT

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Compare outcomes in patients undergoing one-level or two-level anterior lumbar interbody fusion (ALIF) at L4-S1. BACKGROUND: Although ALIF may deliver restoration of lumbar lordosis and improvement in clinical outcomes, it also carries risk of complications including major vascular injury. Whether one-level and two-level ALIF offers similar outcomes is not known. METHODS: Adults who underwent one-level L4-L5 or L5-S1 ALIF and two-level L4-S1 ALIF at a single academic institution were identified. Patient demographics, procedural characteristics, improvement in spinopelvic alignment, and one-year postoperative patient-reported outcome measures (PROMs) and complications were compared. Multivariate regression analyses, accounting for age, gender, and Charlson Comorbidity Index (CCI), were also performed. RESULTS: In total, 158 ALIF patients (111 one-level and 47 two-level) were included, with mean age of 51.4 years, 57.0% female, mean CCI of 1.2, and mean follow-up of 27.0 months. Surgical time (147.3 min vs. 124.6 min, P=0.002) and hospital length of stay (3.5 d vs. 2.9 d, P=0.036) were higher for two-level ALIF. One-year postoperatively, two-level ALIF patients had more caudal apex of lordosis (P=0.016) and 4.1 mm (P=0.002) and 2.0 mm (P=0.019) higher L4-L5 anterior and posterior disc heights, respectively. PROMs were not statistically different across groups (P>0.05). Finally, two-level ALIF patients were 10.9 times more likely to have in-hospital complications (P=0.040), such as intraoperative vascular injury (11.1% vs. 1.5%, P=0.040) or postoperative ileus (7.4% vs. 0.0%, P=0.027), than one-level ALIF patients. CONCLUSION: In this investigation with greater than one-year follow-up, two-level ALIF in the L4-S1 spine had higher procedural time, length of stay, and approach-related complications than one-level ALIF. Although there were minor improvements in alignment with two-level ALIF, PROMs were comparable with improvements from baseline to last follow-up. These findings may help surgeons carefully weigh the risks and benefits of one- versus two-level ALIF when determining surgical plans for patients. LEVEL OF EVIDENCE IV.