Ankylosing spondylitis is inflammation primarily of the joints of the spine, but it can also involve inflammation of the eye, other joints-especially those in the hips, chest wall, and around the heels-and, on occasion, the shoulders, wrists, hands, knees, ankles, and feet. Although it is unusual, ankylosing spondylitis can also cause changes such as thickening of the major artery (aorta) and the valve in the heart called the aortic valve. Scarring of the lungs also happens in rare cases.

If the inflammation continues over time, it will lead to scarring and permanent damage. In some people the disease is mild and progresses slowly, and symptoms may never become severe. Other people may have a more aggressive disease process.

Whether ankylosing spondylitis gets worse depends on a number of factors such as how old you were when the disease began, how early it was diagnosed, and what joints are involved. While it's too early to tell yet, experts hope that early treatment with newer medicines will slow or minimize the inflammation, prevent scarring, and limit the progression of the disease.

Mild or early ankylosing spondylitis

Ankylosing spondylitis usually starts with dull pain in the low back and back stiffness. Some people with ankylosing spondylitis have "flares" of increased pain and stiffness that may last for several weeks before decreasing again.

• Affected bones of the low back, middle back, hips, or neck may become painful, stiff, and limited in motion. Pain tends to increase slowly over a period of weeks or months, and it is often hard to point to exactly where the pain is. Stiffness is usually worse in the morning and usually lasts for more than one hour. Pain is often noticeable in the early morning hours of sleep, such as between 3 a.m. and 6 a.m. Physical activity often helps decrease pain and stiffness.
• Some people feel tired as the disease progresses. This tiredness comes from the body fighting the inflammatory process that is part of ankylosing spondylitis, and from ongoing stiffness and pain.
• The colored part of the eye (iris) may become inflamed. This inflammation, called iritis, occurs in about 25% to 30% of people with ankylosing spondylitis.¹ Symptoms of iritis include redness and pain in the eye and sensitivity to light.

Severe or advanced ankylosing spondylitis

If, over time, the inflammation continues, it will lead to scarring and permanent damage.

• Scarring in the spine causes the joints of the spine to grow together (fuse, or "ankylose"). As the bones fuse, back pain will gradually go away, but the spine will remain very stiff and unable to bend. The fused spine is more likely to break (fracture) if injured, especially the neck (cervical spine).
• Changes in the spine can cause problems with balance, safety, and mobility. The upper spine can curve forward until eventually the person has a hard time looking straight ahead. In addition, as the spine loses its natural curves it becomes hard to balance for standing and walking, especially if the hips are also affected.
• Breathing can become difficult as the upper body curves forward and the chest wall stiffens. Severe ankylosing spondylitis can also cause scarring of the lungs (pulmonary fibrosis) and an increased risk of lung infection. This can cause even greater problems in smokers because their lungs are already more prone to lung infection and scarring.
• Scarring in the eye can lead to permanent visual impairment and glaucoma.
• In rare cases, the heart muscle can become scarred and the heart valves may become inflamed. The heart may be unable to pump properly (heart failure). The main artery leading from the heart (aorta) can also be affected by becoming inflamed and enlarged near where it leaves the heart.