In the United States, about 129 out of 100,000 people have ankylosing spondylitis. Ankylosing spondylitis (previously referred to as rheumatoid spondylitis, Marie-Strumpell's spondylitis, and poker back) is a chronic inflammatory type of arthritis that primarily affects the sacroiliac joints and the spine. The lower back is most often affected, but the mid-portion of the back and neck can also be involved. Progressive stiffening of the spine is common, and ankylosis (fusion) of some or all of the spinal joints occurs in later years for many but not all patients. There is a concern about fusion occurring in a non-upright position. Good posture, as well as early treatment, is important.

Joints other than the spinal joints can also be involved. The hips, knees, and shoulders may be involved; however, it is uncommon for the small joints of the hands and feet, wrists, or ankles to be affected by ankylosing spondylitis.

Ankylosing spondylitis is classified as one of the spondyloar-thropathies because of shared characteristics with psoriatic arthritis and reactive arthritis. According to the Primer on Rheumatic Diseases (Arthritis Foundation), there is a strong inherited component associated with ankylosing spondylitis. About 90 percent of people with ankylosing spondylitis have the genetic marker HLA-B27. The test for the genetic marker is not definitive for ankylosing spondylitis, but suggests a predisposition to it. Many people with ankylosing spondylitis have family members with the disease. About 6 percent of the general population has the genetic marker as well, but will likely not develop ankylosing spondylitis.

Early diagnosis is important, but it is not uncommon for the diagnosis to come with some difficulty. X-ray evidence of ankylosing spondylitis may not appear for many years. Recognizing common symptoms so you can tell your doctor what you are experiencing is helpful. Common symptoms include:

• Back pain and stiffness that can result in bent posture

• Back pain that persists for more than three months

• Back pain which is dull as opposed to sharp

• Morning stiffness, especially of the back or spine

• Pain in areas other than the back (e.g., ribs, shoulder blades, hips, thighs, heels)

• Iritis (inflammation of the eye)

Both men and women can develop ankylosing spondylitis, but it is three times more prevalent in men. Onset of the disease is usually between fifteen and forty years old, though it can develop at any age. Treatment options are similar to those used to treat rheumatoid arthritis: medications to control inflammation; physical therapy to maintain mobility and joint flexibility; and surgery to repair joint damage. However, there is no surgery to repair the spine for this disease. Ankylosing spondylitis is usually a slow, progressive disease and symptoms range from mild to severe. Most people with ankylosing spondylitis continue to work and function relatively normally. Long duration of the disease can result in neurological, cardiac, and pulmonary complications, but such complications are very rare.