Insights into the complex relationship between pain and imaging-detected structural damage in knee osteoarthritis

Knee osteoarthritis (OA) is a leading cause of chronic pain and disability, yet the relationship between imaging-detected structural damage and clinical pain remains still unclear. This persistent pain-structure discordance limits the effectiveness of current treatments and poses major challenges for clinical trial design and the development of disease-modifying OA drugs. Advances in imaging particularly MRI-based scoring systems have improved characterization of cartilage, bone, synovial, and meniscal pathology, but morphologic imaging alone cannot capture the neurobiological processes that shape the pain experience. This review summarizes pathophysiological changes and pain mechanism related to OA, followed by a review of pain assessment tools, a summary of our current understanding of the association between structural damage and pain experience in knee OA. Finally, we discuss emerging imaging tools, including positron emission tomography, which may help visualize inflammatory and neurobiological processes in both the knee joint and the brain.