Journal of Spine Practice

Published date: Jul 31 2025

Journal Title: Journal of Spine Practice

Issue title: Journal of Spine Practice (JSP): Volume 4, Issue 3

Pages: 126 - 138

DOI: 10.18502/jsp.v4i3.18720

Robin M. Bouttelgierrobin.bouttelgier@uzgent.beDepartment of Neurosurgery, Gent University Hospital, Gent

Dimitri Vanhauwaertdimitri.vanhauwaert@azdelta.beDepartment of Neurosurgery, AZ Delta Hospital, Roeselare

Wim Maenhoudtwim.maenhoudt@azdelta.beDepartment of Neurosurgery, AZ Delta Hospital, Roeselare

Stephanie Du Fourstephanie.dufour@azdelta.beDepartment of Neurosurgery, AZ Delta Hospital, Roeselare

Olivier Van Dammeolivier.vandamme@azdelta.beDepartment of Neurosurgery, AZ Delta Hospital, Roeselare

Jeroen Van Lerbeirghejeroen.vanlerbeirghe@azdelta.beDepartment of Neurosurgery, AZ Delta Hospital, Roeselare

Introduction
Sagittal imbalance significantly impacts outcomes in adult degenerative spine conditions. Lumbar lordosis (LL) restoration is essential for spinopelvic alignment. Posterior or posterolateral fusions using hypo-lordotic implants can exacerbate spinopelvic imbalance by increasing the already existing hypo-lordosis. This study examines the impact of L5-S1 anterior lumbar interbody fusion (ALIF) on sagittal alignment in patients with adjacent segment disease following prior posterior or posterolateral lumbar fusions.

Methods
This retrospective study included 17 patients with a history of lumbar fusions, treated with L5-S1 ALIF at AZ Delta Hospital between 2019 and 2024. Pre-operative and post-operative radiographs were assessed for (proximal and distal) LL and sagittal balance parameters. Changes in alignment were analyzed with paired samples t-tests after verification of normal distribution.

Results
Pre-operative LL averaged at 43.7^∘ (95% CI [36.1–51.3]) and improved significantly to 50.1^∘ (95% CI [43.5–56.7] p < 0.05) post-operatively, primarily due to an increase of distal LL from 25.5^∘ to 35.2^∘ (p < 0.001). The pelvic incidence–lumbar lordosis (PI-LL) mismatch decreased significantly from 39.0^∘ to 18.9^∘ (p < 0.05), while the sagittal vertical axis (SVA) reduced non-significantly from 97.3 mm to 86.7 mm.

Discussion
L5-S1 ALIF has the potential to effectively restore LL and reduce PI-LL mismatch in patients with degenerative spine conditions and a history of lumbar hypo-lordotic fusions. Study limitations include a small sample size, missing full-spine radiographic data in a subset of patients and lack of long-term follow-up. These limitations underscore the need for validation through larger, prospective studies with standardized imaging and clinical follow-up.

Conclusion
This study highlights the efficacy of L5-S1 ALIF in restoring lumbar curvature, reducing PI-LL mismatch and improving sagittal alignment in patients with a history of lumbar fusions. Despite the challenges of fixed hypo-lordosis resulting from previous hypo-lordotic lumbar fusions, our findings demonstrate that L5-S1 ALIF can significantly increase LL and reduce forward trunk inclination. Future studies involving larger patient cohorts and extended follow-up are warranted to validate these findings and evaluate their long-term clinical implications.

Keywords: ALIF, sagittal balance, lumbar lordosis, adjacent segment disease, pelvic incidence, pelvic tilt, sacral slope

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