Advancements in unilateral biportal endoscopic lumbar interbody fusion: a narrative review

Lumbar fusion remains a cornerstone for managing degenerative lumbar disorders. Recently, Unilateral Biportal Endoscopic Lumbar Interbody Fusion (ULIF) has emerged as a key minimally invasive technique with promising clinical outcomes. This narrative review analyzes current applications, technical advancements, and the existing evidence base for ULIF. It also highlights the challenges, controversies, and research gaps that may affect its widespread adoption, offering insights to guide future clinical practice.

A structured literature search of the PubMed, Web of Science, Embase, and Cochrane Library databases was conducted for relevant articles published through August 2025. Search terms included "unilateral biportal endoscopic," "UBE," "biportal endoscopic spine surgery," "lumbar interbody fusion," "ULIF," and "BE-TLIF." This review critically synthesizes findings from clinical studies, technical reports, and systematic reviews focusing on surgical techniques, clinical efficacy, fusion outcomes, and complications associated with ULIF.

ULIF is increasingly utilized for a wide spectrum of lumbar degenerative diseases. Comparative studies indicate that while ULIF yields comparable long-term fusion rates and clinical improvements to minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), it offers distinct advantages, such as reduced intraoperative blood loss and shorter hospital stays. However, these benefits are often offset by longer operative times, particularly during the initial learning curve. Technical innovations, including novel cage designs and navigation systems, aim to enhance fusion and restore sagittal alignment. Despite its potential, the technique's adoption is challenged by this steep learning curve and a distinct complication profile, including concerns regarding dural tears, epidural hematomas, and nerve root injuries. Questions also remain regarding its cost-effectiveness and its ability to achieve superior radiological outcomes.

ULIF represents a safe and effective minimally invasive alternative for treating various lumbar spine disorders. However, its widespread adoption is constrained by its technical demands, a specific complication profile, and unresolved questions regarding its cost-effectiveness and long-term radiological benefits. Future high-quality research, particularly multicenter Randomized Controlled Trials (RCTs), is necessary to definitively establish its long-term efficacy, standardize surgical techniques, and optimize patient safety.