Ankylosing spondylitis (AS) is a form of arthritis that mostly affects the spine.

In this particular type of arthritis, the joints and ligaments of your spine become inflamed and can ultimately become calcified. This can cause back pain and stiffness.

In time, the bones may fuse together, making it difficult to bend and move. AS can affect other joints, and in some cases, it can damage your eyes, heart, or lungs.

AS occurs about twice as often in men as in women, and it is typically diagnosed in the teen years or young adulthood. The cause isn’t entirely understood, but some may have a genetic predisposition toward developing AS.

Read on to learn more about how AS can effect various body systems.

The main area of inflammation is your spine, particularly your lower spine. Pain and stiffness are generally greater in the morning or after a long period of sitting. Moving around usually alleviates the symptoms. Over many years, AS can lead to curvature of your spine, resulting in a stooped posture.

Pain may also occur in your upper spine, neck, and even in your chest. Unlike some other forms of arthritis, AS usually doesn’t affect the fingers. According to the Spondylitis Association of America, about 15 percent of people with AS have jaw inflammation due to involvement of the temporomandibular joint, which can get in the way of chewing.

Chronic inflammation can cause bones to fuse together, restricting your ability to move. If bones in your chest fuse, it could affect your breathing. In some cases, inflammation also occurs in other joints, such as your shoulders, hips, knees, or ankles. This can cause pain and reduced mobility.

Imaging tests, like X-rays and MRI scans, can clearly show areas of inflammation and are useful diagnostic tools. Treatment revolves around reducing inflammation and easing pain. Early treatment may help prevent permanent damage to joints.

Maintaining a straight posture is key, even when you sleep. Choose a hard mattress and avoid thick pillows. Sleeping with your legs straight rather than curled is a good idea. Avoid stooping or slouching when standing or sitting.

In addition to medications, performing low-impact exercises regularly can help you maintain flexibility and reduce pain and stiffness. Swimming and other water exercises are often recommended for people with AS. Your doctor can advise you about what exercises may help, or refer you to a qualified physical therapist. A hot shower or bath can also help relieve soreness.

In severe cases, reconstructive surgery might be considered. But because this surgery may stimulate extra bone growth, its risks need to be carefully weighed against its benefits.

Over many years, severe cases of AS can result in the formation of scars in the bundle of nerves at the spine’s base. This can lead to problems such as incontinence, lack of bowel control, and sexual dysfunction.

AS is more likely to affect your eye than any other organ in your body. Eye inflammation is a problem for about 1 in 3 people with AS.

The result of this inflammation is pain and redness in the eye. The diagnosis is iritis, which intensifies in bright light and can cause vision problems. You should report eye pain or vision problems to your doctor immediately. Blindness is a rare complication, but early treatment is required to help prevent permanent damage to your eye.

In a rare number of cases, people with AS may also develop psoriasis. Psoriasis is an autoimmune skin condition that causes red, scaly patches of skin.

These patches can appear anywhere on your body but are more common on the scalp, elbows, and knees. Sometimes, skin can blister or form lesions. Symptoms include itchiness, tenderness, burning, and stinging. Topical medications can ease discomfort.

Psoriasis arthritis (PsA) occurs in approximately 30 percent of patients with psoriasis and this can affect peripheral joints (hands, knees, elbows, shoulders, feet) as well as the spine. The spinal involvement occurs in 25 to 70 percent of patients with PsA, and in many instances can’t be differentiated from ankylosing spondylitis.

Some people with AS may develop anemia, or general fatigue, caused by a deficiency of red blood cells. Rarely, inflammation caused by AS can affect the area where your aorta and heart connect. This can cause your aorta to enlarge. People with AS are also at increased risk of cardiovascular disease, which can lead to angina, stroke, or heart attack.

You can manage your risk by seeing your doctor regularly if you have high cholesterol, high blood pressure, or diabetes. Try to maintain a healthy weight through a healthy diet and regular exercise. Avoid use of tobacco products.

Only rarely does AS affect the lungs. Inflammation or fusing in joints where your ribs meet your spine can result in poor chest wall movement. You may have difficulty taking deep breaths.

A small number of people develop scarring or fibrosis at the top of their lungs. This can make it difficult to fight off respiratory infections and colds. People with AS shouldn’t smoke.

During a physical examination, your doctor can listen to your breathing to check for problems. Damage to the upper portion of your lungs can be seen on a chest X-ray.

Fatigue is a common problem reported by people with AS. This may be due to the efforts of fighting chronic inflammation. Sleep disrupted by pain may also be a contributing factor of fatigue.

Healthy lifestyle choices — such as eating a nutritious, well-balanced diet and not using tobacco — will help keep you in overall good health.

AS is a chronic disease, but most who have it continue to lead active lives. People with AS should pay special attention to posture and perform daily stretching and breathing exercises. Long-term treatment generally revolves around symptom management.