Ankylosing Spondylitis
Ankylosing spondylitis (AS) is a progressive form of arthritis due to chronic inflammation of the joints of the spine and pelvis.
MusculoskeletalOverview
Ankylosing spondylitis (AS) is a progressive form of arthritis due to chronic inflammation of the joints of the spine and pelvis. With AS, the spaces between the vertebrae of the spine and between the spine and the pelvis remain swollen and inflamed. This swelling and inflammation causes back pain. AS is a progressive disease and the pain and stiffness associated with the inflammation will eventually limit movement.
AS is an autoimmune disease, but its exact cause is unknown. It is more common in men than in women and it often runs in families. The onset of symptoms of AS usually appear in the late teen or young adult years; most people are diagnosed before the age of 30.
AS cannot be cured, but treatments, including medications and lifestyle modifications, can improve the symptoms.
Symptoms
- The symptoms of AS and the disease course vary from person to person.
- The hallmark of AS is “sacroiliitis” or inflammation of the sacroiliac joints – the places where the spine meets the pelvis. In the early stages of AS, patients may also experience mild fever, loss of appetite, and general discomfort. Fatigue is also associated with AS. The chronic inflammation can cause anemia, which also contributes to an overall feeling of tiredness and weakness.
- In some people, AS can affect joints outside of the spine, such as the shoulders, ribs, hips, knees, and feet. It can also affect the sites where the tendons and ligaments attach to the bones. Rarely, AS affects other organs, such as the eyes, bowel, heart, and lungs.
- Almost all cases of AS are characterized by acute, painful episodes (also known as "flares") followed by temporary periods of remission where symptoms subside. Many people with AS have mild episodes of back pain that come and go, but others have severe, ongoing pain and a loss of flexibility of the spine. In severe cases, long-term inflammation leads to calcification that can cause bones of the spine to fuse. Fusion can also stiffen the rib cage, which results in restricted lung capacity and function.
Causes & risk factors
The cause of AS is unknown. Genetic and environmental factors probably contribute to the disease. AS tends to run in families, and the main gene that has been identified to be associated with susceptibility to AS is called HLA-B27. One theory states that AS starts when the defenses of the intestines start breaking down and bacteria from the intestines pass into the bloodstream directly into the region where the sacroiliac joints are located and cause inflammation.
You have an increased risk of AS if you:
- Test positive for the HLA-B27 genetic marker
- Have a family history of AS
- Have frequent gastrointestinal infections
When to get help
See a doctor for ongoing back pain and stiffness that is worse in the morning or after rest and eases with activity, especially if it began before age 40. Early treatment helps preserve mobility.
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All information on this site is provided “as-is” for informational purposes only and is not a substitute for medical advice or treatment. You should consult with a medical professional if you have any questions about your health.