Ankylosing spondylitis (AS) primarily affects the spine and is more common in men.
Ankylosing spondylitis (AS) is a type of inflammatory arthritis. It mostly causes pain and swelling in the spine or the joint that connects the bottom of the spine to the pelvic bone. Other joints can be affected as well. It is a systemic disease, which means it may affect other body parts and organs. The disease tends to run in families. It is more common and more severe in men.
Ankylosing spondylitis can occur at any age, but typically begins between ages 17 and 45. About 10 percent of people with the disease develop symptoms before age 18. AS is much less common among African Americans than people of other racial backgrounds.
The exact cause of ankylosing spondylitis is not clear. Researchers believe that people with certain genes develop AS when they are exposed to a virus, bacteria or another outside factor. The HLA-B27 gene is found in about 90 percent of Caucasians with AS and only 8 percent of Caucasians without AS. But, having the gene doesn’t mean someone will get AS.
AS typically causes lower back, buttocks and hip pain first. Children, however, usually have pain in the hips, knees or heels before the back. Other symptoms of AS may include:
- Pain, swelling, redness and warmth in the toes, heels, ankles, knees, rib cage, upper spine, shoulders and neck (usually develops slowly over several weeks or months).
- Morning stiffness or after long periods of inactivity.
- Back pain during the night or early morning.
- Mild fever.
- Appetite loss.
Over time, the joints and bones of the spine (vertebrae), including the sacrum (the triangle shaped bone at the bottom of the spine), may grow together (fuse). This causes the back to become stiff and hard to move. The rib cage may fuse, making it harder to breath.
Here are other ways AS can affect the body:
- Eyes. Chronic eye inflammation (uveitis or iritis) causes dryness, pain, redness, sensitivity to light and vision problems. Uveitis affects more than one-fourth of people with AS.
- Digestive Tract. Inflammation may lead to Crohn’s disease or ulcerative colitis, causing abdominal pain and diarrhea.
- Heart. Though uncommon, inflammation may affect the largest artery that leads to the heart (aorta). People with AS also have an increased risk for heart attack and stroke.
- Lungs. Complications affecting the lungs are rare, but inflammation may cause shortness of breath and impaired lung function.
It’s important to see a doctor early to get an accurate diagnosis. A primary care doctor may be the first person to treat the joint pain, but a referral to doctor that specializes in treating inflammatory arthritis (rheumatologist) is likely if AS is suspected.
There is no single test to diagnose AS. The doctor will ask about medical history, perform a physical exam and order laboratory tests to rule out other causes of back and hip pain.
- Medical history. The doctor will ask about symptoms, when they started, if they come and go, current medical conditions, medication use and whether family members have arthritis.
- Physical examination. The doctor will look for signs of tenderness, swelling and pain in your spine, hips and sacrum. He will observe how joints move and may check the eyes.
- Blood tests. The doctor may order a test for the HLA-B27 gene. Having this gene doesn’t mean someone has AS, but it can help with diagnosis. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR or sed rate) tests will check for inflammation.
- Imaging tests. The doctor may order X-rays, ultrasound, MRI or CT scans of the pelvis and spine to look for signs of damage.
There is no cure for AS, but treatment goals focus on:
- Relieving pain and stiffness in the back and affected areas.
- Preventing spinal deformity.
- Preventing joint and organ damage.
- Preserving joint function and mobility.
- Improving quality of life.
Early, aggressive treatment is the key to preventing long-term complications and joint damage. A well-rounded treatment plan includes medication, nondrug therapies, healthy lifestyle habits and rarely, surgery.
Learn more about the medications used to treat ankylosing spondylitis at the arthritis drug guide.
Nonsteroidal anti-inflammatory drugs
Disease-modifying antirheumatic drugs
Most people with AS will never need surgery, but joint replacement can help people with severe pain or joint damage. The affected joint is replaced with a metal or ceramic prosthetic.
Regular physical activity is a critical part of managing AS. It helps prevent stiffness and preserves range of motion in the neck and back.
Low-impact exercises that require deep breathing and help with flexibility and posture include walking, swimming, yoga and tai chi. It’s also important to strengthen the trunk (core and back) and legs. Talk to a certified fitness instructor or physical therapist before starting a weight training program or discuss ways to modify moves if you are already physically active.
Physical Therapy and Assistive Devices
A physical therapist teaches strengthening and stretching exercises to help preserve joint function, maintain spinal flexibility and reduce pain. Occupational therapists can prescribe assistive devices and provide tips for protecting joints and making daily tasks easier.
Eat a healthy diet. There’s no special diet for AS. But, eating anti-inflammatory foods, like the ones in the Mediterranean diet (fatty fish, fruits, vegetables, whole grains and extra virgin olive oil), and limiting sugary and processed foods, may help.
Avoid smoking. Smoking worsens overall health, and studies show it can speed up disease activity and spinal and/or joint damage. It can also make it harder to breathe. Your doctor can help you to quit.
Practice good posture. Good posture can ease pain and stiffness. Adjust the height of a computer monitor or desk or use a cushion for neck or back pain. Minimize stooping or remaining in bent positions. Avoid “texting neck”.
Stretch. Stretching exercises, especially after a warm bath or shower, can help ease pain and relieve stiffness.
Pace yourself. Managing AS can cause fatigue. On tough days, pace your activities and take short breaks throughout the day to help reduce inflammation and fatigue.
Americans with ankylosing spondylitis
Men are more likely than women to develop ankylosing spondylitis.
Symptoms usually appear bewteen ages 17 and 45.
People with ankylosing spondylitis develop uveitis, an inflammatory.
Stay in the Know. Live in the Yes.
Join the Live Yes! Arthritis Network. Tell us a little about yourself and you will receive emails packed with the latest information and resources to live your best life and connect with others.