What is psoriatic arthritis?

Psoriatic arthritis is an inflammatory arthritis associated with psoriasis, a chronic skin and nail disease. Psoriasis appears as red patches of skin covered with white, silvery, waxy scales. Psoriasis usually appears for the first time between the ages of 14 and 45 years. Males and females are affected in about equal numbers. You may have psoriasis and osteoarthritis or rheumatoid arthritis, without psoriatic arthritis.

Psoriatic arthritis affects about 10% of people who have psoriasis, often appearing years after the skin condition first appears. However, it can also occur before there is any skin involvement.

What causes psoriatic arthritis?

The exact cause is unknown, but an interplay of immune, genetic and environmental factors are suspected. Up to 40% of patients with psoriatic arthritis may have a family history of psoriasis or arthritis in family members.

What are the signs and symptoms?

• Psoriasis appears as red patches of skin covered with silvery scales. It may be just one small patch of skin, usually in the scalp at the hair margins, on the front of the shin just below the knee or on the front of the forearms just below the elbow. Or, it may be widely spread on the body, head and limbs. Often these patches (called plaques) are itchy and uncomfortable.
• pitting and/or discolouration of fingernails and/or toenails.
• pain and swelling in one or more joints, usually the last joints of the fingers or toes, the wrists, knees or ankles. Some people with psoriatic arthritis may have only one joint affected while in others it may resemble rheumatoid arthritis. The sacroiliac joints and the spine can also be involved. Because of this, psoriatic arthritis belongs to a group of disorders known as the spondyloarthropathies (spondylo = spine; arthropathy = joint disease).
• swelling of fingers and/or toes that gives them a 'sausage' appearance.

Psoriatic arthritis can develop over a long period of time, or it can appear quite suddenly.

How is it diagnosed?

The doctor will ask about symptoms and perform a physical examination. Since the symptoms of this type of arthritis are similar to other forms of arthritis, the doctor may also perform some, or all, of the following tests:

• x-rays to look for changes in bones and joints
• blood tests to rule out other conditions, such as rheumatoid arthritis
• joint fluid tests to rule out gout, another arthritis-related disease that may resemble psoriatic arthritis.

If the skin condition has appeared first, and nails and skin are affected along with the joints, a concrete diagnosis can be made almost immediately. Otherwise a firm diagnosis may have to wait until the development of the skin disease.

Management of psoriatic arthritis

Your doctor may involve other health professionals in developing a programme that will best manage your condition. Overall, good heath and balanced lifestyle will play an important part in your ongoing health.

The goals of treatment are to reduce joint pain and swelling, control the skin patches, and to slow down or prevent joint damage. Treatment may include one or a combination of skin care, medications and other treatments.

Treatment - skin

The skin must be well cared for - especially during the winter. The aim is to reduce the dryness and skin lesions caused by psoriasis.

• use a lotion or lanolin cream
• use non-irritant soaps
• put baby oil in the bathwater or rub it on the skin after showering
• use a humidifer in the winter
• avoid using strong soaps or chemicals.

Sitting in the sun for moderate periods of time is helpful because sunlight slows down cell mutiplication. Too much sunlight acts as a 'trigger factor', however, so avoid sunburn.

Treatment - joints

Depending on the severity of the pain, inflammation and swelling, the health professional will prescribe some or all of the following options:

• Exercise - maintains mobility of your joints and strengthens muscles to protect the joints. An Arthritis Educator or physiotherapist can give you a plan and advice on home exercises.
• Rest
• Heat and cold treatments
• Splints - if the joints in your hands are affected, wearing a splint at night, or a working splint during the day, will help keep your hands in a comfortable position.
• Medications - are used to control psoriasis and improve the appearance of your skin. As well, there will be times when you need to use medication for your arthritis. Pain, inflammation and stiffness caused by the arthritis are usually well controlled with non-steroidal, anti-inflammatory drugs (NSAIDs). These work quickly and are not addictive - they do not lose their beneficial effect. If your arthritis is more severe, a steroid injection into the infected joint will help relieve the pain and inflammation. See also: Medications for arthritis

Support

It is not uncommon to experience stress, depression and fatigue when you have psoriatic arthritis. Arthritis New Zealand and their Arthritis Educators can help you with support and advice. In particular, they can assist with:

• self management courses to help you learn new ways of living a full and satisfying life with arthritis
• advice on diet, exercise, support groups, aids and appliances which can assist you in daily living
• advice and counselling and referrals to other health professionals for further assistance.

Unproven remedies

The promises of quick 'cures' and 'miraculous relief' sound wonderful to a person with a chronic illness. Most of the products advertised in this way, whether drugs, dietary supplements or mechanical devices are not harmful, but worthless, and often expensive and have not been proven effective.

If you are considering using any of these treatments, it would be worthwhile discussing it with your doctor first.

Related topics

For more on arthritis, see Arthritis

Original material supplied by Arthritis New Zealand. Reviewed by everybody, July 2005.