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Why do joints become damaged?

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There are three main things that keep your joints stable. These are:

  • the close fit of your bones
  • the capsule and ligaments, which are like strong elastic and keep your bones together
  • the muscles and tendons that make your joint move.

If you have arthritis, several parts of the joint can become damaged.

Joint instability and deformity

Your bones and cartilage may be damaged and your muscles may weaken, causing the joint to become unstable. This means that the joint may gradually change shape and deformities can develop. 

Joint damage in rheumatoid arthritis

If you have rheumatoid arthritis your ligaments may become stretched and slack because of repeated swelling of the joint. These changes may start quite early in the condition.

The way you use your joints can contribute to the development of deformities. Your hands are particularly at risk because of their many small joints and constant use. These deformities can cause problems with activities that need a good grip. Common deformities in people with rheumatoid arthritis include:

  • your wrist or knuckles slipping downwards so that they partially dislocate (subluxation) 
  • your fingers bending over towards your little finger (ulnar drift) 
  • your finger or thumb joints buckling (swan neck, boutonniere finger or z-shaped thumb deformities).

About half of all people who have rheumatoid arthritis will have developed some hand deformities after about five years, so have a look at your own hands carefully and see if any of them have started to happen.

 Hand deformities in rheumatoid arthritis

Joint damage in osteoarthritis

If you have osteoarthritis, which is a wear and repair process, knobbly fingers (Heberden’s nodes and Bouchard’s nodes) are common types of deformity. You may also notice reduced movement and pain at the base of your thumb. This is often associated with buckling of the main thumb joint.

Hand deformities in osteoarthritis

If you notice early that any of your joints are becoming deformed, whether you have rheumatoid arthritis or osteoarthritis, you can change the way you do things to reduce the strain on them.

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