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PSORIATIC ARTHRITIS

What is Psoriatic Arthritis ?

Psoriasis is a common skin disease of unknown cause. A small proportion of patients with psoriasis also have their joints affected. Arthritis is inflammation of a joint. The joint is made up of two bones covered with cartilage. They are surrounded by the joint capsule (or sheath). The lining of the capsule is called synovium. This becomes inflamed in psoriatic arthritis with thickening, swelling and fluid which collects in the joint. When severe, the inflammation in the synovium can spread into the cartilage and underlying bone and destroy it. The bone-ends can become exposed, grate on each other and become deformed. The symptoms are a red, hot joint which is painful for you to move or use. It is often stiff in the mornings or if rested for some time. The fluid in the joint can be seen as swelling. As the fluid pressure builds up it becomes more painful. The severity of the joint inflammation varies. On some days the symptoms are worse than on others. As the inflammation in a joint settles, it may leave scar tissue which makes the joint difficult to move, or even deformed. It often affects the small joints of the hands and feet. It can, however, merely stay in one joint, such as a knee, for many years. A rare kind of psoriatic arthritis affects the back, producing a very stiff and sometimes bent spine.

How does Psoriatic Arthritis occur ?

It is not known why people with psoriasis get an inflammatory arthritis nor why it affects different joints in different people at different ages. The cause is thought to be a change in the body's immune (defence) system. Instead of reacting only to foreign agents (like bacteria), it reacts against the body's own tissues producing an inflammation: in this case in the joints.

Why does Psoriatic Arthritis occur ?

Psoriasis and psoriatic arthritis tend to run in families. Those with inflammation of the spine have often inherited the gene HLA B27, which can be identified from a blood test. It is not known what triggers the arthritis in a patient with psoriasis. Some people may even get the arthritis before the skin problem develops. Certainly the skin problem and the arthritis are not always equally severe.

Treatment Involved for Psoriatic Arthritis

Psoriatic arthritis is a chronic disease with better and worse periods. As the disease behaves differently in each patient, the treatments used will vary. You will usually be given non-steroidal anti-inflammatory drugs (NSAIDs) first. These reduce inflammation, pain and stiffness. There are over 40 different types. Individual patients benefit from different drugs, so many drugs may need to be tried. You are likely to do well on NSAIDs. However, some patients have severe disability and need a drug that can halt the progress of the disease. There are a number of drugs that can do this: they are the so-called disease-modifying or immunosuppressant drugs. They have to be taken over at least 2 to 3 months before any effect can be seen. They all have some side-effects and need monitoring by a hospital or specialist. Methotrexate is currently the drug of choice as it can improve both the joints and skin. The tablets are taken as a once weekly dose. Sulphasalazine (Salazopyrine EC) may also be given to you. Steroids (cortisone-like drugs which suppress inflammation) are rarely used in psoriatic arthritis. However, in severe disease they may occasionally be helpful. The dose is reduced to the minimum as soon as the disease responds. A drug called anti-TNF alpha has recently become available in the UK (Etanercept or Infliximab). It is expensive, but causes impressive pain relief in some patients. Its use is not yet officially licensed for psoriatic arthritis. Physiotherapy will be suggested to you, to keep the joints moving freely and to prevent deformity. Exercise sometimes keeps muscles and ligaments strong. You will have to attend a physiotherapy department for courses of treatment, and do exercises at home as well. Hydrotherapy exercises in a warmed swimming pool are often very helpful to painful lower limb joints. Occupational therapy will demonstrate how to protect joints in normal daily life. An inflamed joint can also be put in a splint to prevent a deformity developing. An orthotist may supply you with special tailor-made shoes, splints or appliances to help support joints. When the inflammation is active, it is important not to get too tired. It is important for you to have a sensible amount of bed rest and a positive attitude to the disease. Try not to let your disability get you down.

During Treatment for Psoriatic Arthritis

Most people respond rapidly to NSAIDs. The disease-modifying drugs take 2 to 3 months to take effect. NSAIDs may cause indigestion, a rash and ankle swelling due to fluid retention. Patients on disease modifying drugs need to attend specialist clinics: blood tests must be done regularly to pick up a low white blood count which signifies that the dose is too high. Urine checks are needed in some cases. Rare side-effects are mouth ulcers, rashes and hair loss. Treatment may continue for months or years. If any unusual symptoms develop, be sure to let you doctor know immediately. It may be important not to get pregnant, or to father a baby during treatment. You should consult your doctor about this.

If Psoriatic Arthritis is Left Untreated

The disease is very variable. Some people need very little treatment. With severe untreated arthritis, less than 1 in 10 would end up severely incapacitated.

Effects on Family of Psoriatic Arthritis

Family should provide support and a positive approach for you. A chronic disorder such as this can be very disheartening.