Classification of Psoriatic Arthritis

Presentations of Psoriatic Arthritis

Psoriatic arthritis (PsA) causes swelling, pain and stiffness in your joints and in areas where your tendons and ligaments connect to bone.

Just like psoriasis, PsA can range from mild to severe. Mild PsA is sometimes referred to as oligoarticular, meaning it affects four or fewer joints in the body. More severe PsA is often called polyarticular, meaning it affects five or more joints. But regardless of the severity, psoriatic arthritis can have a profound impact on pain, the ability to do daily tasks and move comfortably.

PsA can involve the peripheral joints (found in your arms and legs, including the elbows, wrists, hands and feet) or less commonly, the axial skeleton (spine, hips and shoulders).

Spondylitis [spon-dil-I-tis]

Spondylitis is inflammation of the spinal column which affects 7 to 32 percent of people living with psoriatic arthritis. It is common in people living with psoriatic arthritis and can occur with other forms of PsA at the same time. Symptoms include inflammation with stiffness of the neck, lower back and sacroiliac joints. Spinal arthritis makes joint motion in these areas painful and difficult.

Enthesitis [en-thi-SAI-tis]

Roughly 50 percent of people living with PsA experience enthesitis. Enthesitis refers to inflammation of entheses, the site where ligaments or tendons connect to the bones. Common locations for enthesitis include the bottoms of the feet, the Achilles' tendons, and where ligaments attach to the ribs, spine, and pelvis. This type is unique to PsA and does not occur with other forms of arthritis like rheumatoid arthritis or osteoarthritis. Enthesitis can make the tissues in the affected area become ropey (known as fibrosis) or solid (known as ossification or calcification).

Dactylitis [dak-til-AI-tis]

Dactylitis, or "sausage digits," refers to inflammation or swelling of an entire finger or toe. About 40 percent of people living with PsA experience dactylitis. It occurs due to inflammation of the small joints and enthesitis of the surrounding tendons. Dactylitis is another sign of PsA. Usually dactylitis involves a few fingers and/or toes, but not in a symmetric pattern meaning different toes and fingers are affected on different sides of the body.

Early Clues to PsA

Read more

When PsA Invades the Jaw

Read more
Illustrated graphic of people around a rocket ship and computer.

Advance Online

Read more

Request Your PsA E-Kit

Get more information about managing symptoms of psoriatic arthritis and living well.

Order your free kit

Stay in the Know.

Expert tips, can’t-miss events and the latest news, straight to your inbox.

National Health Council Standards of ExcellenceCharity NavigatorCommunity Health Charities logoTwill Care logo

Copyright © 1996-2023 National Psoriasis Foundation/USA


Duplication, rebroadcast, republication, or other use of content appearing on this website is prohibited without written permission of the National Psoriasis Foundation (NPF).


NPF does not endorse or accept any responsibility for the content of external websites.


NPF does not endorse any specific treatments or medications for psoriasis and psoriatic arthritis.

We use cookies to offer you a better experience and analyze our site traffic. By continuing to use this website, you consent to the use of cookies in accordance with our Privacy Policy.