Osteoarthritis occurs when there is damage in and around the joints which the body cannot repair. The exact causes are not known but there are several factors thought to increase your risk of developing the condition.
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.
The types of damage that can lead to osteoarthritis includes:
ligament or tendon problems
inflammation in the joint itself or within the bone
damage to the protective surface that allows your joints to move smoothly (cartilage)
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.
It is not known why the breakdown in the repair process that leads to osteoarthritis occurs. However, several factors are thought to contribute to the development of osteoarthritis. These are outlined below.
Joint injury – Osteoarthritis can develop in a joint 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.
Other conditions (secondary arthritis) – Sometimes, osteoarthritis can occur in joints severely damaged by a previous or existing condition, such as rheumatoid arthritis or gout. It is possible for secondary osteoarthritis to develop many years after the initial damage to your joint.
Age – The risk of osteoarthritis increases as you get older due to weaker muscles or joints that may have become worn out.
Family history – In some cases, osteoarthritis may run in families. Genetic studies have not identified a single gene responsible, 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 obese people.