# Anterior Versus Posterior Lumbar Interbody Fusion at L5-S1 in Hybrid Surgery for Adult Spinal Deformity: A Propensity Score Matching Analysis of Radiographic Results, Mechanical Complications, and Clinical Outcomes

## TL;DR

This study compares anterior and posterior spinal fusion surgeries for adult spinal deformity, finding minor benefits in one approach for specific spinal alignment outcomes.

## Contribution

The study provides a propensity score-matched comparison of anterior and posterior fusion at L5–S1 in adult spinal deformity surgery.

## Key findings

- Anterior fusion (ALIF51) showed greater L5–S1 segmental lordosis compared to posterior fusion (PLIF51).
- ALIF51 resulted in a smaller C7–sagittal vertical axis (SVA) compared to PLIF51.
- Mechanical complication rates and clinical outcomes were similar between the two surgical approaches.

## Abstract

Objectives: The aim of this study was to compare the radiographic results, mechanical complications, and clinical outcomes between anterior and posterior lumbar interbody fusion at L5–S1 (ALIF51 and PLIF51 groups, respectively) using a matched cohort of patients undergoing long fusion for adult spinal deformity (ASD). Methods: Patients who underwent hybrid surgery of ≥5-level fusion to the pelvis with a minimum follow-up duration of 2 years were included. The baseline characteristics of the groups were controlled using a propensity score matching analysis. The radiographic results, mechanical complications such as proximal junctional kyphosis/failure and metal failure, and clinical outcomes were compared between the groups. Results: In total, 79 patients were assigned to each group with comparable baseline data, except for a higher frequency of anterior column realignment procedures in the PLIF51 group than in the ALIF51 group (49.4% vs. 31.6%). At the last follow-up, L5–S1 segmental lordosis (SL) was significantly greater in the ALIF51 group than in the PLIF51 group (12.1° vs. 7.3°, p < 0.001). The final C7–sagittal vertical axis (SVA) was significantly smaller in the ALIF51 group than in the PLIF51 group (25.4 mm vs. 35.5 mm, p = 0.032). However, other global sagittal parameters were comparable between the groups. The mechanical complication rates, including metal failure at L5–S1, and the final clinical outcomes were comparable between the groups. Conclusions: ALIF51 has modest advantages over PLIF51 in terms of better restoring L5–S1 SL and C7–SVA with avoiding more invasive procedures above the L5–S1 levels. Other sagittal parameters, mechanical complication rates, and clinical outcomes did not differ between the groups.