It is a disease which affects the joints and surrounding tissues

Below are some simple explanations, of how joints work and what joints are effected in arthritis.

What are joints? The body has hundreds of bones. Joints are for movement. Joints are structures where bones meet. Joints that are healthy allow the bones to move easily together. This picture shows some of the body's joints

The body has Large and Small Joints The red circles show some of the small joints in the hands and feet. Most of the small joints in a foot, are situated around the toes. Most of the small joints in a hand, are situated in the fingers.

Joints can move in different ways Joints move in different ways including in circles or from side to side (for example the hip joint) or some joints move very little (for example the pelvis). The knee is a large joint, which moves backwards and forwards

What are the surrounding tissues? There are lots of tissues or materials surrounding the joints. They all help the joint to move more easily or hold it in place or cushion the joints to stop the bones from rubbing together. There are different names for the different materials and the things that they do: Muscles move our joints. If we have weak muscles the joints don't move so well. It is important we keep using our muscles even if we have arthritis. Ligaments hold the bones together at the joints and look like thick white bands of tissue. Tendons attach the muscles to the bones so that the bones can be moved. Cartilage coats the end of the bones to stop the bones rubbing together.

The onset of Arthritis This image shows a Knee joint, first in its perfect form and then showing what happens to it when affected with arthritis. Arthritis damages the cartilage and the bone, therefore making it painful to walk. The joint becomes bigger than normal, which can lead to pain, stiffness and sometimes deformity. Different joints and surrounding tissues can be affected so there are lots of different types of arthritis. The two most common types are osteoarthritis and rheumatoid arthritis.