Abstract
Dear Editor,
We revisited with great interest the “AOSpine Consensus Paper on Nomenclature for Working-Channel Endoscopic Spinal Procedures” by Hofstetter et al. 1 The rigorous and collaborative effort by global experts in developing this consensus has been pivotal in standardizing terminology in endoscopic spine surgery (ESS). Nonetheless, the classification of unilateral biportal endoscopy (UBE) as an endoscopy-assisted technique warrants re-evaluation in light of evolving surgical practices, growing clinical evidence, and the need for semantic precision.
The original definition of full-endoscopic spine surgery (FESS)—centered around working-channel endoscopes—was well suited to the technological context when first proposed. 2 However, it now appears overly restrictive, as it overlooks the evolution of ESS, procedural diversification, and the foundational principle of endoscopy: visualization. The term “endoscopy” derives from the Greek endoscópesis, meaning “to observe inside”, and historically refers to minimally invasive, visualization-based techniques using optical devices. 3 In its literal and conceptual sense, full-endoscopy encompasses procedures performed exclusively and continuously under endoscopic visualization—without reliance on direct vision, loupes, microscopes, or exoscopes—aligning with the diachronic principle of primum non nocere through a minimally invasive approach. 3 Despite its biportal configuration, UBE fulfills all these criteria within a saline-irrigated environment, comparable to working-channel techniques.2,4,5
The classification of FESS should prioritize the method and exclusivity of visualization over technical attributes such as endoscope design (with or without an integrated working-channel), instruments trajectory (through or outside the endoscope), or number of portals. This principle-based approach better aligns with the etymology of “full-endoscopy”, 3 the core tenets of ESS, and the imperative to incorporate evolving techniques like UBE, which conceptually and functionally meet the defining characteristics of FESS.
By contrast, the current consensus defines endoscopy-assisted spine surgery as procedures in which the endoscope is used solely for visualization, while instrumentation is performed through separate, non-endoscopic pathways. 1 The term “endoscopy-assisted” was already well established in medical nomenclature prior to this consensus, typically referring to procedures in which endoscopy complements other visualization modalities. 6 Such techniques involve larger incisions in air-based environments and often include steps—such as surgical access, decompression, or fusion—not performed endoscopically.6,7
UBE provides direct, continuous and exclusive endoscopic access to the spine—with high-resolution imaging, magnification, and off-axis viewing—via small incisions in a fluid medium, clearly distinguishing it from hybrid techniques.4-7 Analogous multiportal endoscopic procedures, such as arthroscopic joint surgery and transnasal pituitary surgery, are widely recognized as full-endoscopic, reinforcing that endoscope type, portal number, or spatial separation between instruments and endoscope, should not preclude UBE from the same classification.8,9
Given its expanding clinical application, favorable outcomes, ergonomic benefits, superior visualization, cost-efficiency, and shorter learning curve, UBE is well positioned to assume an increasingly prominent role in ESS.4,5 While nomenclature must arise from expert consensus, we offer this perspective as a scholarly contribution to ongoing discourse. Upon closer examination, UBE clearly fulfills all fundamental criteria of FESS and should be reclassified accordingly. Such reclassification would enhance terminological precision, scientific communication, evidence-based research, and broader adoption within contemporary spinal surgery.
