Psoriatic Arthritis

Psoriatic arthritis is a type of arthritis. It usually affects people who have psoriasis or a biological family history of psoriasis.

Arthritis is a common disorder that affects your joints. It causes pain and inflammation in and around your joints. Psoriasis causes inflammation in your skin. Psoriasis rashes are patches of discolored skin covered with scales. These thick, scaly areas are called plaques. It can also make your fingernails and toenails thicken and look flaky or pitted (covered in tiny indentations).

Both arthritis and psoriasis are autoimmune diseases. An autoimmune disease is the result of your immune system accidentally attacking your body instead of protecting it. Psoriatic arthritis happens when you develop psoriasis symptoms on your skin and inflammation in your joints.

Psoriatic arthritis symptoms on your skin and in your joints usually come and go in periods called flares. A healthcare provider will suggest treatments to relieve your symptoms during a flare.

Visit a healthcare provider if you notice new symptoms on your skin or pain, swelling or stiffness in your joints.

How common is it?

Less than 1% of all people experience psoriatic arthritis. But it’s much more common in people who have psoriasis. Around 30% of people with psoriasis develop psoriatic arthritis at some point in their life.

What are the five forms of psoriatic arthritis?

A healthcare provider might classify psoriatic arthritis based on which joints it affects or on which side of your body you experience symptoms. The five forms of psoriatic arthritis include:

• Distal interphalangeal predominant psoriatic arthritis: This affects the joints near the end of your fingers and toes (phalanges). It’s the most common type of psoriatic arthritis that affects your fingernails and toenails. Your nails might look discolored, flaky or pitted.
• Symmetric polyarthritis: Polyarthritis affects five or more joints at the same time. Symmetric polyarthritis affects the same joints on both sides of your body. For example, both of your knees and both elbows. It’s one of the most common types of psoriatic arthritis.
• Asymmetric oligoarticular psoriatic arthritis: This affects two to four joints on both sides of your body — one knee and one elbow, for example. It’s the other most common form of psoriatic arthritis (along with symmetric polyarthritis).
• Spondylitis: Your spine is made of 33 bones called vertebrae (the plural form of vertebra). Spondylitis causes inflammation and other symptoms in the joints between your vertebrae. It can also cause pain in your hips and shoulders.
• Arthritis mutilans: This causes severe symptoms in your hands and feet. The inflammation is usually severe enough to cause bone loss (osteolysis). It’s the rarest form of psoriatic arthritis. Less than 5% of all people with psoriatic arthritis have arthritis mutilans.