Acronyms of Arthritis 2: Types

Being diagnosed with arthritis can change a lot of things, but you’re not alone! Whether through organizations like the Arthritis Foundation, online forums like Reddit, or friends and family, there are so many options for finding support from others who understand what it’s like to live with arthritis. We deal with a lot of complicated medical terms, so we often shorten them to abbreviations and acronyms.

In my last Acronyms of Arthritis article, I covered treatments (MTX, SSZ, DMARDs, NSAIDs). Here, I’ll be covering all the different letters you might hear people use when talking about their type of arthritis.

Common arthritic conditions (alphabetical)

AS

Ankylosing spondylitis is the most well-known type of spondyloarthritis (see below for more about spondyloarthritis).

AS is a mixture of an autoimmune and autoinflammatory disaease. It causes inflammation and pain in the low back. If left untreated, it can cause the spine and pelvis joints to fuse together due to bone growth. AS can also spread to other joints, most commonly large joints like hips, knees, and shoulders.

JA / JIA / JRA

Juvenile arthritis is a general term to refer to any kind of arthritis that starts in childhood. It’s most often used by the Arthritis Foundation for their JA programs.

Juvenile idiopathic arthritis is a type of autoimmune inflammatory arthritis that begins in childhood. It’s called “idiopathic” because it has no known origin. There are 6 main subtypes of JIA, and each has different symptoms.

• Oligoarticular JIA affects only a few joints (less than 5).
• Polyarticular JIA affects a lot of joints (5 or more).
• Systemic JIA (sJIA) includes whole-body symptoms like fevers and rashes.
• Psoriatic JIA (PsA) is arthritis in kids who have psoriasis rashes.
• Enthesitis-related JIA (ERA) is arthritis in kids who also have pain where muscles, tendons, and ligaments meet bone (entheses). It usually affects large joints and the back, and it’s a type of spondyloarthritis.
• Undifferentiated JIA is diagnosed in kids who have inflammation in joints but no pattern that fits another type.

JIA used to be called juvenile rheumatoid arthritis; however, it was updated because kids with JIA don’t always go on to have RA in adulthood.

OA

Osteoarthritis is the kind of arthritis caused by wear-and-tear on joints. It is usually diagnosed in people who are older, but it can also be diagnosed in younger people due to injury or other health conditions (like EDS, discussed below).

OA happens when the cartilage that cushions joints wears away. This causes the bones to contact each other, which is painful.

PsA

Psoriatic arthritis is another type of spondyloarthritis. It occurs in people who also have the skin condition psoriasis. It can cause symptoms similar to AS: pain in the low back, tendonitis, and uveitis. It also more commonly causes finger pain and swelling.

Some people with psoriasis are diagnosed with AS due to the pattern of their arthritis, while others receive a PsA diagnosis.

SpA / axSpA / pSpA / JSpA

Spondyloarthritis is the general category of arthritis that affects the spine and sometimes other joints. SpA is associated with uveitis, inflammatory bowel disease, psoriasis, and tendonitis.

Due to some recent changes in classification, there are a lot more SpA acronyms floating around than there used to be. Buckle in; this one’s confusing.

New system:

• axSpA: Axial spondyloarthritis is a new label for SpA that affects the spine. AS is a type of axSpA, but not all axSpA is AS. This is because original definitions of AS are very restrictive and require joint damage to be visible on x-ray. axSpA allows the disease to be diagnosed before it gets that far. Yay!
• pSpA: Peripheral spondyloarthritis is arthritis and enthesitis in someone with a history of back pain or family history of SpA. This means you can be diagnosed with SpA without having current back pain.

Old system:

• AS: Ankylosing spondylitis. See above.
• EnA: Enteropathic arthritis, or arthritis with Crohn’s disease or ulcerative colitis.
• JSpA: Juvenile spondyloarthritis includes juvenile AS, enthesitis-related JIA, juvenile PsA, and more.
• PsA: Psoriatic arthritis. See above.
• ReA: Reactive arthritis. See below.
• USpA: Undifferentiated spondyloarthritis, or spondyloarthritis symptoms that don’t fit one of the other types.

RA

Rheumatoid arthritis is the most well-known autoimmune arthritis. It typically causes pain and swelling starting with small joints, like hands and feet. Effected joints may feel tender and warm, and they look swollen. It can also spread to larger joints, like knees, hips, and shoulders. If left untreated, RA can cause changes to the shape of your fingers.

Related and less common conditions (alphabetical)

DISH

Diffuse idiopathic skeletal hyperostosis causes the soft tissues around the spine to harden. This can cause pain and nerve compression. It usually appears in older people.

EDS

Ehlers-Danlos syndrome is a group of genetic conditions that affect connective tissue. There are a number of subtypes, but EDS is usually characterized by joints that extend more than normal (hypermobility), skin that stretches more than normal (hyperelasticity), and skin that is more fragile than normal.

EDS can cause early OA, and you can have EDS with other kinds of arthritis as well.

PMR

Polymyalgia rheumatica causes aching and stiffness but often no visible swelling. It can make it hard to move parts of the body, especially the shoulders, upper back, and hips. It often appears in older people.

PR

Palindromic rheumatism has symptoms like RA that come and go suddenly. Between attacks, you have no symptoms, and there isn’t lasting joint damage. However, about half of people with PR eventually develop RA.

ReA

Reactive arthritis is a reaction to an infection by your body. It usually comes on after gastrointestinal or genitourinary infections. It’s a type of spondyloarthritis that causes joint pain, eye problems, and genitourinary symptoms. Most people recover within 12 months, but it can sometimes become chronic.

SLE

Systemic lupus erythematosus is an autoimmune disease that causes inflammation in the joints, skin, and other organs. You may also hear SLE referred to as “lupus.” It affects many different parts of the body, so each case has different symptoms. Fatigue, joint pain, headaches, fevers, and light sensitivity are common.

This is just a short introduction, but it should be a great starting point to understanding when people talk about their arthritis. I’ll be continuing this series on the acronyms of arthritis with tests and anatomy in the near future. Did I miss something you’ve been wondering about? Let me know in the comments!

-Bri

I love creating resources like this, but each one takes a lot of time and research. If this post helped you, consider supporting the site with by donating a “coffee” on Ko-Fi! Thanks! <3