Ankylosing spondylitis  (pronounced AN-kee-low-sing SPON-dil-eye-tiss) is a chronic (long-term) autoimmune disease, similar to rheumatoid arthritis, that primarily affects the lower spine of the more than two million Americans estimated to be afflicted.

According to the Centers for Disease Control (CDC), over two million Americans are estimated to have some form of ankylosing spondylitis (pronounced AN-kee-low-sing SPON-dil-eye-tiss), an autoimmune/inflammatory disease that primarily strikes the base of the spine.

Also called Bechterew's or Marie-Strumpell disease, ankylosing spondylitis (AS) is a chronic disease with no known cause and no known...