Osteoarthritis
Osteoarthritis is a disease of cartilage and bone caused by wear and tear, or trauma to the joint. Since it is not associated (unlike rheumatoid arthritis) with the presence of inflammatory cells in the joints that are affected it is sometimes called osteoarthrosis. Initially the cartilage lining the joint cracks and splits - a process called fibrillation - and eventually falls away, exposing the underlying bone which over a period of time becomes thicker and may develop outgrowths at the edges of the joint called osteophytes. There may be cyst formation underneath the thickened bone. X-rays initially show narrowing of the space between the bones, and later bone-to-bone contact and bone thickening. Blood tests are characteristically normal.
This is by far the commonest condition affecting joints in the developed world, increasing with age so that over the age of 65 some 60-65 per cent of people suffer from it. While it can affect any joint those which bear the most weight (the hip and the knee) or make the most movements (finger joints) are more frequently affected. It is more likely to occur in any joint that has suffered damage, in women than in men, in those who have undergone long periods of hard exercise, and in those with a family history since it appears that there is a genetic component to this disease. The underlying mechanism is uncertain but it is thought possibly to involve an imbalance in the absorption and deposition of cartilage. There is initially stiffness and pain which characteristically worsens with usage and as the day goes on, though some patients find the pain worse at rest. The pain may be relieved by using painkillers and by injecting steroids into the joint, and weight loss together with physiotherapy and walking aids may also help. Many, however, come to require joint replacement - a highly successful operation.
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