Osteoarthritis of the knee (OA) is the most common form of arthritis and effects large numbers of elders, limiting their function and causing significant levels of pain. Historically seen as a disease of ‘wear and tear’, the modern diagnostic criteria for OA is a combination of clinical features, examination and radiological findings.
However, these broad criteria encompass a heterogeneous range of presentations and may overlook several clinically relevant variables which can affect patient management and outcome. Examples of this include poor correlation between radiological findings and symptom severity, as well as the reported inconsistent efficacy of several interventions within the literature. It has previously been hypothesized that several sub categories exist within OA, each with their own unique pain presentations, or pain phenotypes.