Failed Back Surgery Syndrome Reframed: A Patient-centered Clinical Taxonomy

Abstract Background: Failed back surgery syndrome (FBSS) is a complex clinical entity characterized by persistent or recurrent pain following spinal surgery. Traditional terminology and classification systems are inadequate for guiding clinical management and research. Objective: To provide a comprehensive review of FBSS incorporating a practical clinical classification system based on pain characteristics and temporal patterns and synthesizing current evidence on epidemiology, pathophysiology, diagnostic approaches, and treatment modalities. Materials and Methods: We conducted a systematic literature search across multiple databases (PubMed, SciSpace, and Google Scholar), focusing on publications from 2019 to 2025. We integrated our findings with a novel clinical classification framework that stratifies patients based on post-operative pain patterns relative to pre-operative symptoms. Results: FBSS affects 10%–40% of patients undergoing spinal surgery. A three-group clinical classification system emerges as most practical: Group 1 (“Same Pain”)—persistent pre-operative pain patterns suggesting target–generator mismatch; Group 2 (“Modified Pain”)—altered pain characteristics post-surgery; and Group 3 (“New Pain”)—completely novel pain phenotypes. Each group had distinct etiologies, diagnostic approaches, and treatment strategies. Conclusions: FBSS requires reconceptualization as a heterogeneous syndrome rather than as a single diagnostic entity. The proposed clinical classification system provides a framework for systematic evaluation and targeted interventions, moving beyond purely anatomical considerations to patient-centered pain phenotyping.