What Is Psoriatic Arthritis?
Psoriatic arthritis (PsA) is a form of inflammatory arthritis that can affect some of the millions of people who have psoriasis. Psoriasis is a skin disease that causes a red, scaly rash, most often on your elbows, knees, ankles, feet, hands, and other areas.
Is Psoriatic Arthritis an Autoimmune Disease?
Yes. Psoriatic arthritis is an autoimmune condition, meaning it happens when your body’s immune system goes awry and attacks healthy tissue by mistake. PsA most often affects your skin and your joints, which can become swollen, stiff, and painful. Over time, if you don’t treat it, the inflammation that comes along with it can damage joints and tissues.
Are There Different Types of Psoriatic Arthritis?
Like other types of arthritis, psoriatic arthritis can be more or less severe. Your rheumatologist will take into account how many joints it affects and how severe it is when coming up with your treatment plan. PsA can be:
- Oligoarticular: Usually a milder type that affects four or fewer joints
- Polyarticular: A more severe type that affects four or more joints
Where Can Psoriatic Arthritis Affect Your Body?
This condition can involve different body parts:
- Spondylitis affects the spinal column and may cause inflammation and stiffness in your neck, lower back, spinal vertebrae, or sacroiliac region (pelvic area), which can make it hard to move. Spondylitis also can attack connective tissue, like ligaments, or cause arthritic disease in the joints of the arms, hips, legs, or feet.
- Enthesitis is inflammation of entheses, the place where ligaments or tendons insert into your bones. You’re likely to get it on the bottoms of the feet, the Achilles tendons, and the places where ligaments attach to the ribs, spine, and pelvis. It only affects people with PsA, and not other types of arthritis like rheumatoid arthritis or osteoarthritis. Over time, enthesitis can make tissues in the affected area become ropey (your doctor will call this fibrosis) or solid (the doctor might refer to this as ossification or calcification).
- Dactylitis, or “sausage digits,” is inflammation that affects an entire finger or toe. It happens when small joints and entheses of the surrounding tendons get inflamed. Dactylitis is another hallmark of psoriatic arthritis. It usually involves a few fingers and/or toes, but not in a symmetrical pattern. Unlike other types of arthritis, PsA can affect different toes and fingers on different sides of the body.
What Are the Symptoms of Psoriatic Arthritis?
The symptoms of psoriatic arthritis include:
- Swollen fingers and toes. Psoriatic arthritis can cause a painful, sausage-like swelling of your fingers and toes. Your doctor may call it dactylitis. You might notice swelling and deformities in your hands and feet before other major joint symptoms.
- Foot pain. Psoriatic arthritis can also cause pain at the points where tendons and ligaments attach to your bones. Your doctor might call it enthesitis. It often affects the back of your heel (Achilles tendinitis) or the sole of your foot (plantar fasciitis).
- Lower back pain. Psoriatic arthritis can lead to a condition called spondylitis, which causes inflammation of the joints between the vertebrae of your spine and in the joints between your spine and pelvis (sacroiliitis).
What Causes Psoriatic Arthritis?
Doctors aren’t sure what causes psoriatic arthritis, but they believe these things can play a role:
- Genetics. Your genes, along with the immune system, likely play a role in determining who will get the disorder. Having a parent with psoriasis triples the chance of getting psoriasis yourself and thus increases the chance of having psoriatic arthritis.
- Infection. An infection that triggers your immune system could be to blame. Psoriasis, for example, is often triggered by strep throat.
What Are the Risk Factors for Psoriatic Arthritis?
- You have psoriasis. About 10% to 30% of people with psoriasis get psoriatic arthritis. It affects men and women equally.
- Your age. You can get the condition at any age, but it usually affects people between the ages of 30 and 50.
- Family history. As many as 40% of people with psoriatic arthritis have a family history of skin or joint disease.
How Is Psoriatic Arthritis Treated?
Medical treatments for psoriatic arthritis include:
- Non-steroidal anti-inflammatory drugs (NSAIDs). These are over-the-counter medications like ibuprofen and naproxen.
- Disease-modifying antirheumatic drugs (DMARDs). These can slow or stop pain, swelling, and joint and tissue damage. If NSAIDs don’t work, your doctor will try DMARDs. They may take longer to have an effect.
- Immunosuppressants. If you can’t take a DMARD, you might get a type of drug called an immunosuppressant. As the name suggests, these drugs really rein in your immune system, which is what’s causing the problem in an autoimmune condition like PsA. But they can also make it more likely that you’ll get an infection.
- Biologics. If immune suppression doesn't work, your doctor may prescribe a biologic. These are a newer type of DMARD. Rather than tamp down your entire immune system, these medications block a protein that causes inflammation.
- Enzyme inhibitor. This works by blocking a specific enzyme, a kind of protein, called PDE-4. That helps to slow other reactions that lead to inflammation.
- Steroids. These can help control inflammation, but doctors don’t use them often for PsA because they can make your skin rash worse. Doctors prescribe steroids only when you really need them. If you use them for a long time, you could have serious side effects such as brittle bones, weight gain, hypertension, and diabetes.
- Surgery. A severely damaged joint can be replaced with a new one made from metal and plastic.
What Triggers a Psoriatic Arthritis Flare?
Certain things may trigger psoriasis, including:
- Not taking your medication
- Injury to the skin, like a scrape or sunburn
- Lack of sleep
- Extra weight
Is There a Cure for Psoriatic Arthritis?
There is no cure for psoriatic arthritis. But the use of biologic agents has made remission a real possibility.