As part of normal life, your joints are exposed to a constant low level of damage. In most cases, your body will repair the damage itself. Usually, the repair process will pass unnoticed and you will not experience any symptoms.
Osteoarthritis occurs when there is damage in and around the joint which the body cannot repair. This can include ligaments or tendon problems, inflammation in the joint itself or within the bone and damage to the protective surface (cartilage) that allows your joints to move smoothly.
Your joints may become knobbly where your bones begin to protrude, forming bony lumps called osteophytes. As your bones thicken and broaden, your joints will become stiff, painful and difficult to move. There may also be a build-up of fluid in your joints because of the inflammation, which can cause them to swell up.
Contributory factors
It is not known why the breakdown in the repair process that leads to osteoarthritis occurs. However, it is thought that several factors probably contribute to the development of osteoarthritis. These are outlined below.
Joint injury or disease
Osteoarthritis can develop in a joint that has been damaged by an injury or operation. Overusing your joint when it has not had enough time to heal after an injury or operation can also contribute to osteoarthritis in later life.
Sometimes, osteoarthritis can occur in joints that have been severely damaged by a previous or existing condition, such as rheumatoid arthritis. Rheumatoid arthritis is a form of arthritis that is caused by your body’s immune system.
Osteoarthritis that develops due to damage or another condition is known as secondary osteoarthritis. It is possible for secondary osteoarthritis to develop many years after the initial damage to your joint.
Family history
In some cases, osteoarthritis may run in families. Genetic studies have not identified a single gene responsible for any of the areas affected, so it seems likely that many genes make small contributions. This means it is unlikely that a genetic test for osteoarthritis will become available in the near future.
Being obese
Research into the causes of osteoarthritis has shown that being obese puts excess strain on your joints, particularly those that bear most of your weight, such as your knees and hips. As a result, osteoarthritis can often be worse in people who are obese.
