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Physiology of osteoarthritis?

Osteoarthritis (OA) is a synovial joint disorder involving cartilage, bone and the synovial membrane. It can affect small and large joints
OA can be diagnosed from a persistent history of pain, stiffness and loss of function. X-ray is the gold standard
Risk factors include: age, being female; obesity; metabolic syndrome; repeated kneeling or twisting; or handling heavy weights
OA pain is caused by inflammatory mediators, which lead to central sensitisation of the pain processing cells in the dorsal horn of the spinal cord
Hip OA affects between 0.9% and 27% of the population, and the rates of knee OA are between 17% and 47%

Osteoarthritis (OA) is a synovial joint disorder involving cartilage, bone and synovial membrane. Onset and progress of the condition is usually slow; symptoms of pain, stiffness and restricted function usually emerge in people aged over 40, and prevalence rises with increasing age.

It is difficult to specify prevalence of OA because of the different joints involved. It can affect both small joints, such as those in the thumb, toes and fingers, and the large load-bearing joints of the hip and knee.

Prevalence varies between populations due to factors such as genetics and environment. Dagenais et al (2009), who carried out a review of studies providing data about the prevalence of hip OA, found it affects between 0.9% and 27% of the population. Evidence suggests the rates of knee OA are between 17% and 47% (Horvath et al, 2010; Salve et al, 2010)

OA is often classed as a degenerative disease because the affected joints deteriorate over time. It is also commonly known as a non-inflammatory condition where pain is generated by movement of the diseased joint even though inflammation is a symptom (see below).