Osteoarthritis seems to develop when people are in their 50s; most people with it are over 65 years old. Women are more likely than men to have osteoarthritis - especially in their knees and hands.

If you've developed osteoarthritis there is a lot you can do to reduce the impact it has on your life. If you don't have it, you can take steps to avoid it.

What causes osteoarthritis?

Osteoarthritis is the result of a series of processes that happen to our joints over time. Movable joints are complicated pieces of engineering involving:

• bones
• cartilage
• a tough layer of tissue that forms a capsule to help hold the bones together
• lubrication from the 'synovial membrane' that lines the capsule
• strong elastic ligaments to keep the bones and capsule in place
• surrounding muscles that are connected to the bones by tendons

As we get older our cartilage can become brittle and rough. The bone beneath the cartilage tries to compensate and ends up creating knobbly growths known as osteophytes or 'bone spurs'. The synovial membrane can get thicker which reduces the space inside the joint and can lead to inflammation. Cartilage can break away from the bone leaving the ends of the bones to rub together. This is very painful and can lead to the joint changing shape.

Osteoarthritis doesn't develop according to a set pattern. Changes can be very gradual. Most people find that their joints become stiff and painful to move.

Preventing osteoarthritis

Clearly it pays to look after your joints, by:

• keeping your weight in check by exercising regularly and carefully
• keeping the muscles around your joints strong
• The more overweight you are the higher your chance of getting osteoarthritis, especially in the knees. The most obese people are six times more likely to develop osteoarthritis than those at their ideal weight.

Having weak muscles makes osteoarthritis more likely. Our joints don't 'wear out' with normal use - it is lack of use that puts them at risk. To avoid osteoarthritis, do exercise that strengthens muscles so that the joints are well-supported and working well. Always exercise in soft-soled footwear that acts as a good shock absorber for the joints. To find out more see our exercise section.

Exercise can be very helpful for people who have osteoarthritis - but it is important to get it right. Seek professional advice from a physiotherapist about the sort of exercise that will most suit you. See the Arthritis Care Campaign website for more information.

The question of whether or not what you eat can help to prevent osteoarthritis is controversial – there is no good scientific evidence either way. But while it's not yet possible to give advice about diet and osteoarthritis, remember that lots of fruit, vegetables and fish will help to keep your bones, muscles and cartilage in good health. Find out more in our healthy eating section.