Osteoarthritis is a chronic degenerative disease associated with joint pain and loss of joint function. It has an estimated incidence of 4 out of every 100 people and significantly reduces the quality of life in affected individuals. The major symptoms are chronic pain, swelling and stiffness; severe, chronic joint pain is often the central factor that causes patients to seek medical attention. Within the affected joint, there is focal degradation and remodelling of articular cartilage, new bone formation (osteophytes) and mild synovitis. Several mechanisms are thought to contribute to osteoarthritic joint pain. These include mild synovial inflammation, bone oedema, ligament stretching, osteophyte formation and cartilage-derived mediators. Changes in joint biomechanics and muscle strength also influence the severity and duration of joint pain in osteoarthritis. Within the nervous system, the relative contributions of peripheral afferent nociceptive fibres and central mechanisms remain to be defined, and there is limited information on the phenotype of sensory neurons in the OA joint. Importantly, there is no relation between clinical severity, as measured by radiographic changes, and the presence and severity of joint pain. Patients with severe joint pain may have normal joint architecture as determined by X-ray, whereas patients with considerable evidence of joint remodelling may not have significant joint pain. Treatments for osteoarthritic joint pain include non-steroidal anti-inflammatory compounds, exercise, corrective shoes and surgical intervention. There remains a critical need for improved control of joint pain in osteoarthritis. This book brings together contributions from key investigators in the area of osteoarthritic joint pain. It covers the clinical presentation of joint pain, the pathways involved in joint pain, osteoarthritis disease processes and pain, experimental models and pain control. The discussions provide insights into the nature of osteoarthritic joint pain, identify key studies needed to advance understanding of the problem, highlight possible intervention points and indicate future pathways towards a better treatment of osteoarthritic joint pain.
