Overview of Ankylosing Spondylitis

Ankylosing spondylitis is a type of arthritis that causes inflammation in the joints and ligaments of the spine. Normally, the joints and ligaments in the spine help us move and bend. If you have ankylosing spondylitis, over time, the inflammation in the joints and tissues of the spine can cause stiffness. In severe cases, this may cause the vertebrae (bones in the spine) to fuse (grow together). When the vertebrae fuse, it can lead to a rigid and inflexible spine. (For more information about the anatomy of the spine, see our Back Pain Health Topic.)

Many people with ankylosing spondylitis have mild episodes of back pain and stiffness that come and go. But others have severe, ongoing pain with loss of flexibility in the spine. In addition, other symptoms may develop if other areas of the body—such as the hips, ribs, shoulders, knees, ankles, and feet—are affected by the disease.

There is no cure for ankylosing spondylitis. Doctors recommend treatments that may include exercise and medications to help manage pain, control inflammation, improve posture and body position, and slow the progression of the disease. With treatment, most people with ankylosing spondylitis can have productive lives.

Who Gets Ankylosing Spondylitis?

Anyone can get ankylosing spondylitis; however, certain factors may increase your risk for developing the disease. These factors include:

  • Family history and genetics. If you have a family history of ankylosing spondylitis, you are more likely to develop the disease.
  • Age. Most people develop symptoms of ankylosing spondylitis before age 45.   However, some people develop the disease when they are children or teens.
  • Other conditions. People who have Crohn’s disease, ulcerative colitis, or psoriasis may be more likely to develop the disease.

Symptoms of Ankylosing Spondylitis

The most common symptom of ankylosing spondylitis is lower back and/or hip pain and stiffness. Over time, the symptoms may progress to other areas of the spine. The pain typically worsens during periods of rest or inactivity, which may cause some people to experience more pain during the middle of the night or after prolonged sitting. Usually, moving and exercise can help improve pain. 

Symptoms of ankylosing spondylitis vary from person to person. Some people have mild episodes of pain that come and go, while others will have chronic, severe pain. The symptoms of ankylosing spondylitis, whether mild or severe, may worsen in “flares” and improve during periods of remission. 

Because the disease can affect other areas of the body, other symptoms may develop and may include:

  • Pain, stiffness, and inflammation in other joints, such as the ribs, shoulders, knees, or feet.
  • Difficulty taking deep breaths if the joints connecting the ribs are affected.
  • Vision changes and eye pain due to uveitis, which is inflammation of the eye.
  • Fatigue, or feeling very tired.
  • Loss of appetite and weight loss.
  • Skin rashes.
  • Abdominal pain and loose bowel movements.

Causes of Ankylosing Spondylitis

Researchers do not know the cause of ankylosing spondylitis. However, studies show that both genes and environment may lead to the development of the disease. Researchers know that the HLA-B27 gene increases the risk of developing ankylosing spondylitis, but this does not mean you will get the disease if you have the gene. Many people have the gene and never develop ankylosing spondylitis, which tells researchers that environmental factors also play a role.  

Researchers continue to discover many other gene variations that may cause the disease; however, HLA-B27 is the primary gene that increases your risk for developing ankylosing spondylitis.

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