类风关-Rheumatoid Arthritis

What is rheumatoid arthritis?

Arthritis means inflammation of the joints. Rheumatoid arthritis (RA) is a common form of arthritis. About 1 in 50 people develop RA at some stage in their life. It can happen to anyone, and it is not a hereditary disease. It can develop at any age, but most commonly starts in middle adult life (aged 40-60). It is three times more common in women than in men.

Understanding joints

A joint is where two bones meet. Joints allow movement and flexibility of various parts of the body. The movement of the bones is cased by muscles which pull on tendons that are attached to bone.

Cartilage covers the end of bones. Between the cartilage of two bones which form a joint there is a small amount of thick fluid called synovial fluid. This fluid 'lubricates' the joint which allows smooth movement between the bones.

The synovial fluid is made by the synovium. This is the tissue that surrounds the joint. The outer part of the synovium is called the capsule. This is tough, gives the joint stability, and stops the bones from moving 'out of joint'. Surrounding ligaments and muscles also help to give support and stability to joints.

What causes rheumatoid arthritis?

RA is thought to be an 'autoimmune disease'. The immune system normally makes antibodies to attack bacteria, viruses, and other 'germs'. In people with autoimmune diseases, the immune system makes antibodies against tissues of the body. It is not clear why this happens. Some people seem to have a tendency to develop autoimmune diseases. In such people, something might trigger the immune system to attack the body's own tissues. The 'trigger' is not known.

In people with RA, antibodies are formed against the synovium (the tissue that surrounds each joint). This causes inflammation in and around affected joints. Over time, the inflammation can cause damage to the joint, the cartilage, and parts of the bone near to the joint.

Which joints are affected in rheumatoid arthritis?

The most commonly affected joints are the small joints of the fingers, thumbs, wrists, feet, and ankles. However, any joint may be affected. The knees are quite commonly affected. Less commonly the hips, shoulders, elbows, and neck are involved. It is often symmetrical. So, for example, if a joint is affected in a right arm, the same joint in the left arm is also often affected.

In some people, just a few joints are affected. In others, many joints are involved.

What are the symptoms of rheumatoid arthritis?

Joint symptoms
The common main symptoms are pain and stiffness of affected joints. The stiffness is usually worse first thing in the morning, or after you have been resting. The inflammation causes swelling around the affected joints.

Other symptoms
These are known as 'extra-articular' symptoms of RA (meaning 'outside of the joints'). A variety of symptoms may occur. The cause of some of these is not fully understood.

• Small painless lumps or 'nodules' develop in about 1 in 4 cases. These commonly occur on the skin over the elbows and forearms, but usually do no harm.
• Inflammation around tendons may occur. This is because the tissue which covers tendons is similar to the synovium around the joints.
• Anaemia and tiredness are common.
• A fever, feeling unwell, weight loss, and muscle aches and pains sometimes occur.
• In a few cases inflammation develops in other parts of the body such as the lungs, heart, blood vessels, or eyes. This is uncommon but can cause various symptoms and problems which are sometimes serious.

How does rheumatoid arthritis develop and progress?

In most cases the symptoms develop gradually - over several weeks or so. Typically, you may first develop some stiffness in the hands, wrists, or soles of the feet in the morning which eases by mid-day. This may come and go for a while, but then becomes regular. You may then notice some pain and swelling in the same joints. More joints such as the knees may then become affected.

In a small number of cases, less common patterns are seen. For example:

• In some cases pain and swelling develops quickly in many joints - over a few days or so.
• Some people have bouts of symptoms which affect several joints. Each bout lasts a few days, and then goes away. Several bouts may occur before persistent symptoms develop.
• In some people, usually young women, the disease affects just one or two joints at first, often the knees.
• The non-joint symptoms such as muscle pains, anaemia, weight loss, and fever are sometimes more obvious at first before joint symptoms develop.

RA can vary greatly from person to person. It is usually a chronic relapsing condition. Chronic means that it is persistent. Relapsing means that at times the disease flares-up (relapses), and at other times it settles down. There is usually no apparent reason why the inflammation may flare-up for a while, and then settle down.

Most people with RA have this pattern of flare-ups followed by better spells. In some people, months or even years may go by between flare-ups. Some damage may be done to affected joints during each flare-up. The amount of disability which develops usually depends on how much damage is done over time to the affected joints. In a minority of cases the disease is constantly progressive, and severe joint damage and disability develop quite quickly.

Smoking seems to be a possible factor as, on average, the severity of RA tends to be worse in smokers than non-smokers.

Joint damage
Inflammation can damage the cartilage which may become eroded or worn. The bone underneath may become thinned. The joint capsule and nearby ligaments and tissues around the joint may also become damaged. Joint damage develops gradually. Over time it may lead to deformities. It may become difficult to use the affected joints. For example, the fingers and wrists are commonly affected, so a good grip and other tasks using the hands may become difficult.

Most people with RA develop some damage to affected joints. The amount of damage can range from mild to severe. At the outset of the disease it is difficult to predict for an individual how badly the disease will progress.

How is rheumatoid arthritis diagnosed?

There is no single test which clearly diagnoses early RA. When you first develop joint pains, it may be difficult for a doctor to say that you definitely have RA. This is because there are many other causes of joint pains.

Blood tests can detect inflammation, characteristic antibodies, and anaemia. These may suggest that you have RA, but do not prove that you definitely have it as these blood results can be caused by other conditions.

You may have a time of uncertainty when early symptoms 'could be' RA. In time, X-rays of joints may begin to show typical erosions (early damage) and other features of RA which makes the diagnosis more certain.

Some other associated diseases and possible complications

Associated conditions
The risk of developing certain other conditions is higher in people with RA. These include: heart disease, stroke, infections (joint infections and non-joint infections), gut problems, osteoporosis (thinning of the bones), and certain cancers.

It is not entirely clear why these conditions develop more commonly in people with RA. One reason is that, on average, people with RA tend to have more 'risk factors' for developing some of these conditions. For example:

• Lack of exercise and high blood pressure are 'risk factors' for developing heart disease and stroke. People with RA may not be able to exercise very easily, and some of the drugs used to treat RA may increase blood pressure.
• Some of the drugs used to treat RA suppress the immune system. This may be a factor for the increased risk of developing infections and certain cancers.
• Poor mobility and steroid drugs increase the risk of developing osteoporosis.
• Some of the drugs that are used to treat RA can upset the lining of the gut. This sometimes causes gut and stomach problems.

Other complications
Other complications which may develop include:

• Carpal tunnel syndrome. This is relatively common. It causes pressure on the main nerve going into the hand. This can cause pain, tingling and numbness in parts of the hand. (See separate leaflet called 'Carpal Tunnel Syndrome' for details.)
• Tendon rupture sometimes occurs (particularly the tendons on the back of the fingers).
• Cervical myelopathy. This is an uncommon but serious complication of severe, long-standing RA. It is caused by a 'dislocation' of joints at the top of the spine. This can cause pressure on the spinal cord.

What are the treatments for rheumatoid arthritis?

There is no cure for RA. However, much can be done to help. The aims of treatment are:

1. To reduce pain and stiffness in affected joints as much as possible.
2. To prevent joint damage as much as possible.
3. To minimise any disability caused by pain, joint damage, or deformity.
4. To reduce the risk of developing associated conditions such as heart disease.

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