Ankylosing spondylitis (AS) is a chronic form of arthritis. It mostly affects the bones and joints at the base of the spine where it connects with the pelvis. These joints can become swollen and inflamed. Over time, the affected spinal bones may join together.
AS is the main member of a family of similar forms of arthritis called spondyloarthritis. Other members include psoriatic arthritis, arthritis of inflammatory bowel disease and reactive arthritis. The family of arthritis appears to be quite common and affects up to 1 in 100 people.
The cause of AS is unknown. Genes seem to play a role. Most people with AS are positive for the HLA-B27 gene.
The disease often begins between ages 20 and 40, but it may begin before age 10. It affects more males than females.
AS starts with low back pain that comes and goes. Low back pain becomes present most of the time as the condition progresses.
Other parts of your body that may be stiff and painful include:
Fatigue is also a common symptom.
Less common symptoms include:
AS may occur with other conditions, such as:
Tests may include:
Your health care provider may prescribe drugs such as NSAIDs to reduce swelling and pain.
You may also need stronger medicines to control pain and swelling, such as:
Surgery, such as hip replacement, may be done if pain or joint damage is severe.
Exercises can help improve posture and breathing. Lying flat on your back at night can help you keep a normal posture.
The course of the disease is hard to predict. Over time, signs and symptoms of AS flareup (relapse) and quiet down (remission). Most people are able to function well unless they have a lot of damage to the hips. Joining a support group of others with the same problem may often help.
Treatment with NSAIDS often reduces the pain and swelling. Treatment with TNF inhibitors appears to slow progression of the spine arthritis.
Rarely, people with ankylosing spondylitis may have problems with:
Call your provider if:
Reviewed By: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.