Overview of Spondyloarthritis

A person may have both axial and peripheral symptoms. The predominant symptoms (whether they are axial or peripheral) will determine the category, and the specific diagnosis.

A hallmark symptom of axial spondyloarthritis (axSpA) is inflammatory back pain, frequently characterized by a dull ache felt deep in the lower back, or buttocks. It is associated with inflammation of the sacroiliac (SI) joints, which are the joints linking the lowest part of the spine to the pelvis.

Inflammatory back pain usually begins before age 45, develops gradually, persists longer than three months, improves with physical activity but not rest, and can cause stiffness in the morning that lasts 30 minutes or longer. Though the lower back is usually impacted first, in some people inflammatory pain can start in the neck, or other areas. Other joints and organs can also become involved, including the hips, shoulders, eyes (iritis), gut (inflammatory bowel disease), and skin (psoriasis).

AxSpA is a broad category that includes people with and without characteristic bone changes or fusion in the spine. Doctors further classify adults as having one of two types of axSpA:

To learn more about the experiences of people living with axSpA, please visit our interactive map.

Not all people with axSpA will have bone changes that are visible on x-rays. When other signs and symptoms of axSpA are present, but spinal changes are not visible on x-ray, the diagnosis is non-radiographic axial spondyloarthritis (nr-axSpA). AS and nr-axSpA are thus part of the same axSpA disease spectrum and present with many of the same symptoms. The main difference is that those with nr-axSpA don’t show bone changes on x-rays, although inflammation can be spotted with the help of MRI. Some people with nr-axSpA progress to developing AS, although many do not.

Peripheral spondyloarthritis (pSpA) is characterized by inflammation and pain in joints and/or tendons primarily located outside the spine. Commonly involved sites include joints in the hands, wrists, elbows, shoulders, knees, ankles, and feet. Inflammation of the tendons can occur in the fingers or toes (dactylitis) or where tendons and ligaments attach to bone (enthesitis). Other organs can also become involved, including the eyes (iritis), gut (inflammatory bowel disease), and skin (psoriasis).

PSpA encompasses a number of distinct, though closely related conditions, including psoriatic arthritis, enteropathic arthritis, reactive arthritis, and undifferentiated arthritis.