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 - Northwestern Memorial Hospital - Chicago

Ankylosing Spondylitis

Ankylosing spondylitis is a form of rheumatoid arthritis in the joints of the spine. It causes chronic inflammation of the spine and nearby structures.

Causes of Ankylosing Spondylitis

While the cause of ankylosing spondylitis is as yet unknown, there are genes that are associated with increased susceptibility to the disease, including HLA-B27. This gene is present in over 95 percent of Caucasians with ankylosing spondylitis.

About eight percent of Americans have this gene, but less than five percent with the HLA-B27 gene actually develop ankylosing spondylitis. Two additional genes:

  • ERAP1 (formerly known as ARTS1)
  • IL23R

Are also indicated as increasing the risk of developing ankylosing spondylitis. Environmental factors may trigger the disease in those with these genes.

Signs & Symptoms of Ankylosing Spondylitis

A key sign of ankylosing spondylitis is sacroiliitis (inflammation of the sacroiliac joints, where the spine joins the pelvis).

In some patients, it can affect joints outside of the spine, such as:

  • Shoulders
  • Ribs
  • Hips
  • Knees
  • Feet

It may also affect the entheses (where tendons and ligaments attach to the bones) it may also affect other organs, including:

  • Eyes
  • Bowel
  • Heart (rarely)
  • Lungs (rarely)

Diagnosis & Testing for Ankylosing Spondylitis

Your doctor will perform a physical examination and will ask about your medical history. Questions about your medical history may include:

  • How long you have had back pain
  • Location of the pain
  • Whether other joints are affected
  • If the back pain worsens or lessens with exercise or inactivity
  • Whether you have fatigue or other problems
  • If you have had an recent gastrointestinal illness
  • Whether anyone in your family has back problems or arthritis
  • If you have skin rashes such as psoriasis

Your doctor may have you move and bend in order to determine the flexibility of your spine.

A blood test may be performed to determine whether you have the HLA-B27 gene, although the blood test is not without limitations—just having the HLA-B27 gene does not mean one will always get ankylosing spondylitis.


Because heredity and genetics plays a role in the development of ankylosing spondylitis, prevention of it is not possible. But being aware of risk factors and lifestyle choices that can increase this risk can help.

If you are a smoker, you should quit—smoking can cause particular problems for people who have ankylosing spondylitis, since the disease can impact the mobility of your rib cage, and, therefore, your ability to breathe. Smoking further impairs your lung capacity, which can magnify the effect.

Treatment options for ankylosing spondylitis involve relief of pain and stiffness resulting from the condition, as well as avoiding complications and spinal deformity.

The ideal course of treatment occurs before the disease damages your joints permanently.


The most commonly prescribed medicines for treatment of ankylosing spondylitis are nonsteroidal anti-inflammatory drugs (NSAIDs), which offer relief from inflammation, pain and stiffness.

In some cases, NSAIDs may be insufficient, in which case your physician may recommend drugs like tumor necrosis factor (TNF) blockers, which are administered through an intravenous injection under the skin.

TNF is a cell protein that induces an inflammatory response in rheumatoid arthritis, and TNF blockers target this protein, thereby reducing inflammation. Some well-known TNF blockers are:

  • Adalimumab (Humira™)
  • Etanercept (Enbrel™)
  • Infliximab (Remicade™)

There can be side effects with long-term use of these medications, and you should discuss this with your physician.


Physical therapy offers a patient pain relief and overall improvement in physical condition with specially designed exercises that are tailored for your needs.

The physical therapist may give you stretching and range-of-motion exercises to maintain flexibility in your joints, as well as abdominal and back exercises to help your posture, which will be impacted as the condition worsens over time, if measures aren’t taken to ensure proper posture.

Breathing exercises may also help you maintain your lung capacity, which can be adversely impacted by the disease.


It is rare for people with ankylosing spondylitis to require surgery, although it may occur in instances where there has been severe damage to a joint or if the condition is causing severe pain.

Last UpdateAugust 2, 2012