Understanding the Complexity of Pain in Osteoarthritis Through the Use of Pain Phenotyping: Current Evidence

Purpose of reviewThis narrative review highlights recent literature pertaining to pain phenotyping in osteoarthritis (OA) by summarizing recent novel approaches and promising future directions.Recent findingsWe report on four studies in knee OA that have added knowledge regarding longitudinal validation of pain phenotypes constructed with phenotypic domains other than pain that are highly stable over time; the existence of a pain susceptibility phenotype, defined by the presence of sensitivity to pressure pain thresholds and a lack of presence of psychosocial factors; the novelty and importance of movement-evoked pain supporting the association of positive quantitative sensory testing (QST) findings with greater intensity and frequency of spontaneous pain; and the external validation of a chronic pain phenotype in an independent data set that was previously identified by a systematic review. One study of people with hip OA subgrouped participants using daily pain ratings over 6 weeks demonstrating that both intermittent and constant pain are highly present in early stages of the disease, and those with higher pain intensity experience greater variability of pain.SummaryCollectively these studies have contributed new and important knowledge to our understanding of OA pain phenotypes through longitudinal or external validation, which has been a missing element in the literature. The novel examination of a movement-evoked pain phenotype may provide an avenue to greater understanding of pain variability and its correlates, and with their definitive associations with QST, further supports the importance of a mechanism-based approach to pain assessment.