In order to better understand what is going on when a person suffers from some form of arthritis, let us look at how a joint works.

Basically, a joint is where one bone moves on another bone. Ligaments hold the two bones together. The ligaments are like elastic bands, while they keep the bones in place your muscles relax or contract to make the joint move.

Cartilage covers the bone surface to stop the two bones from rubbing directly against each other. The covering of cartilage allows the joint to work smoothly and painlessly.

A capsule surrounds the joint. The space within the joint - the joint cavity - has synovial fluid. Synovial fluid nourishes the joint and the cartilage. The synovial fluid is produced by the synovium (synovial membrane) which lines the joint cavity.

If you have arthritis something goes wrong with the joint(s). What goes wrong depends on what type of arthritis you have. It could be that the cartilage is wearing away, a lack of fluid, autoimmunity (your body attacking itself), infection, or a combination of many factors.

There are over 100 types of arthritis. Here is a description of some common ones, together with the causes:

• Osteoarthritis - cartilage loses its elasticity. If the cartilage is stiff it becomes damaged more easily. The cartilage, which acts as a shock absorber, will gradually wear away in some areas. As the cartilage becomes damaged tendons and ligaments become stretched, causing pain. Eventually the bones may rub against each other causing very severe pain.



• Infectious arthritis (septic arthritic) - an infection in the synovial fluid and tissues of a joint. It is usually caused by bacteria, but could also be caused by fungi or viruses. Bacteria, fungi or viruses may spread through the bloodstream from infected tissue nearby, and infect a joint. Most susceptible people are those who already have some form of arthritis and develop an infection that travels in the bloodstream.


• Juvenile rheumatoid arthritis (JRA) - means arthritis that affects a person aged 16 or less. JRA can be various forms of arthritis; it basically means that a child has it. There are three main types:
  1. Pauciarticular JRA, the most common and mildest. The child experiences pain in up to 4 joints.
  2. Polyarticular JRA affects more joints and is more severe. As time goes by it tends to get worse.
  3. Systemic JRA is the least common. Pain is experienced in many joints. It can spread to organs. This can be the most serious JRA.

The symptoms of arthritis depend on the type of arthritis, for example:

• Osteoarthritis - The symptoms develop slowly and get worse as time goes by. There is pain in a joint, either during or after use, or after a period of inactivity. There will be tenderness when pressure is applied to the joint. The joint will be stiff, especially first thing in the morning. The patient may find it harder to use the joint - it loses its flexibility. Some patients experience a grating sensation when they use the joint. Hard lumps, or bone spurs may appear around the joint. In some cases the joint might swell. The most common affected joints are in the hips, hands, knees and spine.

• Rheumatoid arthritis - The patient often finds the same joints in each side of the body are painfully swollen, inflamed, and stiff. The fingers, arms, legs and wrists are most commonly affected. Symptoms are usually worst on waking up in the morning and the stiffness can last for 30 minutes at this time. The joint is tender when touched. Hands may be red and puffy. There may be rheumatoid nodules (bumps of tissue under the skin of the patient's arms). Many patients with rheumatoid arthritis feel tired most of the time. Weight loss is common.
  
  The smaller joints are usually noticeably affected first. Experts say patients with rheumatoid arthritis have problems with several joints at the same time. As the arthritis progresses it spreads from the smaller joints in your hands, wrists, ankles and feet to your elbows, knees, hips, neck, shoulders and jaw.