Unfortunately the origins of ankylosing spondylitis are not well understood, but genes and heredity play an important role. A gene called HLA-B27 is found in more than 90% of people with ankylosing spondylitis.

Some researchers have also proposed that certain types of bacterial infection may trigger the development of ankylosing spondylitis in individuals who are genetically predisposed. However, despite encouraging evidence, this theory has proven difficult to confirm.

This form of arthritis is much more prevalent in males, and generally is diagnosed before they reach the age of 30.

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Common Ankylosing Spondylitis Characteristics

  • Ankylosing spondylitis often occurs in the teens or early 20's
    This form of arthritis generally affects young adults, commonly beginning before patients are 35 years old. The average age for ankylosing spondylitis diagnosis is 24, although children - as well as older patients - have also been diagnosed with varying stages of the disease.
  • Ankylosing spondylitis occurs more often in males
    Ankylosing spondylitis is diagnosed more often in men, who also tend to have more severe symptoms. Some professionals believe that the disease may actually be equally prevalent in both genders, but diagnosis is often overlooked or missed in women because they tend to have pain in peripheral joints, such as the neck or hips, as well as the back.
  • Ankylosing spondylitis is a chronic disease that varies greatly in severity across both age and gender.
    Many cases are characterized by acute painful episodes known as “flares” that are followed by periods of relative relief. More serious cases can have a rapid onset of severe pain and stiffness all over the body that does not ease for long periods.
Ankylosing Spondylitis
Ankylosing Spondylitis. Enlarge

Severe Ankylosing Spondylitis Characteristics

Patients with crippling joint pain caused by severe cases of ankylosing spondylitis tend to have several distinctive characteristics:

  • A "curled forward" posture - the chin-to-chest stance - which results in a persistent downward gaze
  • Brittle bones in the spine that are prone to fractures
  • Significantly limited mobility and movement, such that the patient is permanently disabled.

As the disease progresses from the low back all the way up the spinal column, patients are at risk of developing significant complications that can increase the pain and disability already experienced. Potential complications include:

  • Cauda equina syndrome, which can cause pervasive extremity numbness, weakness and bowel or bladder dysfunction
  • Spondylodiscitis, an inflammation of the intervertebral disc caused by the hardening of the fibrous tissue that encompasses the disc
  • Limited chest expansion, which may impact the ability to breathe freely.

Learn more about the Development and Progression of Ankylosing Spondylitis.

These complications are quite rare and are generally only seen in the most severe cases of ankylosing spondylitis.

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Written by Judith Frank, MD
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