Osteoarthritis pain masterclass: Moving beyond structure to mechanism-based clinical reasoning.

INTRODUCTION: Osteoarthritis (OA) is a leading cause of pain, disability, and reduced quality of life worldwide. Although OA is commonly interpreted through a structural lens, pain severity is often only weakly related to radiographic severity, suggesting that structure-based models are insufficient to explain many clinical presentations. PURPOSE: This masterclass aims to challenge persistent structural assumptions surrounding OA pain, summarizes the peripheral, central, behavioral, and systemic mechanisms that may shape pain presentation, and provide a mechanism-based clinical reasoning framework to guide assessment and conservative care. In particular, it emphasizes the mismatch between imaging findings and symptoms, the multidimensional nature of pain, and the need to move beyond a purely mechanical interpretation of OA. IMPLICATIONS: Clinicians should move beyond imaging-led reasoning and adopt multidimensional assessment, phenotype-informed interpretation, and individualized multimodal care. OA pain may reflect interacting peripheral nociceptive input, altered pain processing, sleep disturbance, behavioral adaptation, reduced physical reserve, and broader health factors. Exercise and education remain fundamental components of care, but their value depends on how well they are explained, individualized, and matched to the dominant pain presentation. Manual therapy, sleep-related strategies, load modification, pacing, and psychosocially informed interventions may also have a role when selected according to the clinical profile rather than justified by structural findings alone. A mechanism-informed approach may help clinicians improve treatment matching, reduce low-value imaging-based care, and support more coherent, person-centered management of OA pain.