What is Ankylosing Spondylitis, Radiologic Perspective?

Ankylosing spondylitis is a type of arthritis that is due to inflammation of multiple joints, characteristically the spinal facet joints and the sacroiliac joints at the base of the spine. While it tends to affect these joints and the soft tissues around the spine, other joints may also be affected as well as tissues around the joints (entheses, where tendons and ligaments attach to bone). This disorder frequently results in bony ankylosis (or fusion). The term ankylosing is derived from the Greek word ankylos, which means stiffening of a joint. Spondylos means vertebra (or spine). Spondylitis refers to inflammation of one or more vertebrae. Ankylosing spondylitis is usually a chronic and progressive form of arthritis. Ankylosing spondylitis may also involve areas of the body other than the joints, such the eyes, heart, and lungs. Ankylosing spondylitis is very rare. The frequency in the United States is similar to that of the rest of the world. Ankylosing spondylitis primarily affects young males. Males are more likely to have ankylosing spondylitis than females. Most people with the disease develop it at age 15-35 years, with an average age of 26 years at onset.

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