Lateral interbody fusion for adjacent segment disease: a narrative review.

Background and Objective: Adjacent segment disease (ASD) is a late complication of lumbar fusion characterized by persistent symptoms correlating to radiographic changes in the levels immediately above or below the prior fusion. Lateral interbody fusion (LIF) through a direct lateral approach is a minimally invasive and effective surgical treatment for ASD. Biomechanically, LIF for ASD provides significantly decreased motion in multiple planes. While hardware failure and injury to the lumbar plexus are potential complications, these risks may be outweighed by decreased blood loss, shorter operating room (OR) times, and possibly superior patient reported visual analog scale (VAS) scores compared to traditional posterior spinal fusion (PSF) alone. The purpose of this review is to summarize the history, uses, outcomes, and future directions of LIF for ASD. Methods: A review of national databases (PubMed and SCOPUS) was performed using literature from 1900 to 2022. Keywords included terms "LATERAL" and "LUMBAR" and "INTERBODY" and "FUSION" and "ADJACENT" and "SEGMENT" and "DISEASE". Studies that aimed to describe the biomechanical, clinical course and complications, radiological outcomes, biomechanical aspects, need for revision surgery, and/or patient reported outcomes of the XLIF/LIF technique were included. Key Content and Findings: This review includes a brief overview of the natural history of ASD and current approaches to address it. It then summarizes the main indications and utilization of LIF to address ASD, summarizing reported outcomes in regard to biomechanical, clinical, and radiographic outcomes. Conclusions: LIF has emerged as a minimally invasive and effective surgical treatment for ASD. This mini-review suggests that LIF provides a solid foundational biomechanical construct that has been paired with good patient-reported, clinical, and radiographic outcomes. While further research is required, current literature suggests that LIF for ASD results in fewer complications, decreased morbidity, and decreased need for subsequent surgery compared to other commonly utilized techniques.