In this type of arthritis, the joints and ligaments of the spine become inflamed, producing joint pain and stiffness. The disease often presents first in the lower back and over time can progress to the upper back, chest, and neck. AS can also manifest in the joints of the shoulders, knees, hips, or ankles. In some cases the vertebrae grow together, causing the spine to become rigid.

As with other forms of arthritis, AS is a chronic disease that can exhibit a wide variety of symptoms. Genetics appears to play a large role in AS, since approximately one in five people that contract AS have a relative with AS. In addition, the gene HLA-B27 can be found in over ninety percent of people with AS. AS is more common in the male population and most often appears between the ages of 16 and 35. Even so, AS occurs in less than 1% of adults in the United States.

Treatment and disease management typically consists of maintaining good posture while standing, sitting, and sleeping; getting regular exercise to strengthen the back and neck and encourage flexibility of the chest and ribcage; and medications to reduce inflammation and relieve pain. Adherence to these disease management procedures allows most people with AS to lead normal, productive lives.