Despite extensive research, scientists still do not know what causes OA. It is theorized that some type of cartilage damage starts a destructive process that, in genetically susceptible people, results in OA.
While the cause of OA is unknown, many factors are often associated with its development.
Aging
A person's risk for OA increases as he or she gets older, although OA can occur in younger patients, especially those with joint injuries or a history of joint disease (such as hip dysplasia).
Conversely, not every person in their seventies and eighties has OA. OA is not a normal part of the aging process.
Joint Injuries/Wear and Tear
OA occurs early in people who have experienced serious joint trauma, such as football players and ballet dancers. This condition is also encountered more frequently in people who perform heavy labor for a living, as compared to people who work in an office.
Inactivity
The joint cartilage requires frequent compression and relaxation to remain healthy. This activity is believed to help circulate nutrients in the cartilage, which has no vascular supply of its own. People who perform little or no exercise may note that their joints become stiff and painful. This tendency is thought to predispose them to OA.
Obesity
Excess weight puts undue stress on the weight-bearing joints of the body, adding to the wear and tear experienced by the joints. Surprisingly, obese people have an increased incidence of OA in non-weight-bearing joints, such as the fingers and shoulders. Scientists suggest that their fat tissue may release some chemical that predisposes these patients to OA, though this idea is just a theory at this point. Doctors recommend that people with OA try to reach their ideal weight by careful diet and exercise.
Genetics
There appears to be a genetic component to OA. For example, OA of the fingers occurs commonly in families and is most common in women.
While the cause of OA remains obscure, people who are at risk for OA, whether because of genetics or occupation, should take care to minimize their chance of developing this condition. To do so, they can participate in regular exercise (preferably low-impact exercise) and pay careful attention to their diet as a means of sustaining an ideal body weight.