Ankylosing Spondylitis

Medically Reviewed By William C. Lloyd III, MD, FACS

What is ankylosing spondylitis?

Ankylosing spondylitis is a type of arthritis primarily affecting the spine. It is chronic inflammation of the joints between the vertebrae and between the spine and pelvis. Over time, the involved joints can become fused together. The term “ankylosing” refers to the formation of new bone leading to fusion.

There is some confusion about the name because of a change in the classification system for it. Ankylosing spondylitis is now a type of axial spondyloarthritis. Axial refers to the spine, chest and pelvis. There are several types of axial spondyloarthritis diseases. They all involve entheses—sites where ligaments and tendons attach to bones.

Ankylosing spondylitis is an autoimmune disorder. Affected individuals have a unique protein (HLA-B27) that mistakenly triggers the immune system to attack healthy joints. Researchers think the disease may have a genetic component. It generally develops between 20 and 40 years of age and is three times more common in males. Ankylosing spondylitis in women is less common.

Ankylosing spondylitis symptoms usually begin with pain and stiffness in the lower back and pelvis. Symptoms worsen with inactivity, particularly during sleep or in the morning. The disease can improve with exercise.

Over time, it may spread to involve other sections of the spine. It may also begin to limit your mobility, particularly in the lower spine and sometimes in the rib cage.

The course of ankylosing spondylitis is unpredictable. You may experience periods of remission. Unless your hips are severely involved, you have a good chance of retaining fairly good spinal function. Unrelated infections and stress can provoke new attacks.

There is no known prevention of the disorder; but in many cases, medications and exercise can improve both pain and functionality. Doctors recommend surgery only in rare cases of severe pain.

Ankylosing spondylitis is a life-long disorder. It can restrict your mobility, but it is not life-threatening on its own. In rare cases, it can contribute to aortic heart valve and heart rhythm problems, pulmonary fibrosis, or restrictive lung disease. A more common complication is fracture or injury due to spinal damage.

Seek immediate medical care (call 911) for serious symptoms of back injury, such as severe pain, numbness, weakness of the extremities, or urinary and fecal incontinence.

How does ankylosing spondylitis progress?

While there are no formal stages of the disease, ankylosing spondylitis can be progressive. It usually starts as inflammation of the sacroiliac (SI) joint. This joint consists of the sacrum, or bottom portion of the spine, and the iliac bones on either side, the large flared portion of the pelvis. This early inflammation does not show up on X-ray, but may be present on an MRI (magnetic resonance imaging) scan.

The inflammation, called sacroiliitis, causes persistent hip and low back pain and stiffness. In the early stages, the pain and stiffness may only occur on one side. These symptoms are typically worse when waking up and during sleep. Activity through the waking hours usually improves discomfort.

As the disease progresses, the inflammation can spread up the spine to affect the vertebrae. Over time, it triggers new bone growth that can fuse the joints and vertebrae together. When this damage shows up on X-rays, it is technically ankylosing spondylitis. In severe cases, the spine becomes rigid, making it hard to bend.

The disease does not progress in the same way for everyone. Some people have mild symptoms that come and go. Others have severe and persistent pain.

What are the symptoms of ankylosing spondylitis?

Ankylosing spondylitis symptoms commonly start with intermittent bouts of pain in your lower back. Pain and stiffness tend to worsen during sleep, on arising, or during periods of inactivity. Conversely, symptoms frequently improve with exercise.

Although pain is initially concentrated in the SI joints, over time pain may spread to other areas of the spine as well as to other areas of the body. For example, TMJ (temporomandibular joint) involvement is common with ankylosing spondylitis.

Common symptoms of ankylosing spondylitis

You may experience ankylosing spondylitis symptoms daily or sporadically. At times any of these symptoms can be severe:

  • Eventual loss of spinal flexibility

  • Eventual reduced mobility (range of motion in the joint)

  • Fatigue

  • Hip and buttock pain

  • Lower back or sacroiliac pain

  • Neck and shoulder pain

  • Stiffness in the spine

  • Worsening pain and stiffness with inactivity

Other symptoms of ankylosing spondylitis

Less common symptoms are possible, particularly if your disease progresses. These includes:

Serious symptoms that might indicate a life-threatening condition

While ankylosing spondylitis is not life-threatening on its own, the damage to the joints can predispose someone to fracture or injury to the spine. Seek immediate medical care (call 911) for life-threatening symptoms including:

What causes ankylosing spondylitis?

Doctors do not know the exact cause of ankylosing spondylitis. The disease likely has a genetic component. It appears to happen most prominently in young adults between the ages of 20 and 40, with some cases beginning as young as 10. Ankylosing spondylitis also occurs more frequently in males.

Ankylosing spondylitis also involves a variation in the gene HLA-B. This gene helps the immune system tell the difference between foreign invaders and the body’s own tissues. People with ankylosing spondylitis have a variation of this gene called HLA-B27.

However, not everyone with positive HLA-B27 serology will develop ankylosing spondylitis. So, it is not entirely clear how or if this gene variation causes the disease. But there appears to be an autoimmune component to the condition.

In ankylosing spondylitis, long-term inflammation of the SI joints and joints between the vertebrae leads to progressive pain and stiffness. Eventually, the affected joints become fused together.

What are the risk factors for ankylosing spondylitis?

A number of factors seem to increase the risk of developing ankylosing spondylitis. Not all people with risk factors will get ankylosing spondylitis. Risk factors for ankylosing spondylitis include:

  • Demonstration of HLA-B27 gene

  • Family history

  • Male gender assigned at birth (three times greater risk than females)

  • Young adult age (typically between 20 and 40 years)

How do you prevent ankylosing spondylitis?

Disease prevention usually involves changing risk factors that are under your control, but the risk factors for ankylosing spondylitis are not controllable. In addition, doctors do not fully understand what causes the disease. At this time, there is no reliable way to prevent ankylosing spondylitis.

What are some conditions related to ankylosing spondylitis?

Ankylosing spondylitis is the most common form of spondyloarthritis (SpA) disease, or spondyloarthropathy. SpA is an umbrella term for a group of rheumatic inflammatory diseases that cause arthritis. SpA is different from other forms of arthritis because it involves entheses, which are the sites where ligaments and tendons attach to bones.

Other diseases under this umbrella include:

  • Enteropathic arthritis, which occurs with inflammatory bowel disease (IBD)

  • Peripheral spondyloarthritis, which affects joints outside the spine including the fingers, hands, wrists, elbows, knees, ankles, feet and toes

  • Psoriatic arthritis, which causes pain and swelling in the joints and is often connected to psoriasis

  • Reactive arthritis, or Reiter’s syndrome, which occurs in reaction to certain bacterial infections, such as chlamydia, Salmonella or Shigella

How do doctors diagnose ankylosing spondylitis?

To diagnose ankylosing spondylitis, your doctor will take a medical history, perform an exam, and possibly order testing. Questions your doctor may ask include:

  • Where exactly do you feel the pain? Is it only in your back?

  • When did the pain start?

  • Is the pain constant or does it come and go?

  • When is the pain worst?

  • On a scale of 1 to 10 with 10 being the worst pain ever, how severe is your pain?

  • What, if anything, seems to make your pain better or worse?

  • Are you having any other symptoms, such as fatigue or fever?

  • Do you have a family history of back pain?

During the exam, your doctor will evaluate the mobility of your spine and strength of your back. You may need to bend in different directions, walk, move your legs, or take deep breaths to expand your ribcage.

Depending on the results of your exam, your doctor may order testing. There is no specific ankylosing spondylitis test, but the following tests and exams can be useful:

  • Blood tests to check for markers of inflammation and for the HLA-B27 gene

  • Imaging exams, including X-rays and MRIs. X-rays will show damage that occurs later in the disease. MRIs can often find inflammation early in the disease before bone damage shows up on X-rays.

How is ankylosing spondylitis treated?

The most common ankylosing spondylitis treatment includes a nonsteroidal anti-inflammatory drug (NSAID) and exercise.

NSAIDs can often relieve the pain and inflammation of the disease. Regular exercise and physical activity are a vital part of treatment. Exercise can slow disease progression or stop it. Nearly half of all patients respond to NSAID therapy. Common NSAIDs include:

  • Celecoxib (Celebrex)

  • Diclofenac (Voltaren)

  • Ibuprofen (Advil, Motrin)

  • Indomethacin (Indocin, Indocin SR)

  • Meloxicam (Mobic)

  • Naproxen (Aleve, Naprosyn)

  • Oxaprozin (Daypro)

  • Sulindac (Clinoril)

Doctors may use a corticosteroid injection to temporarily relieve joint pain.

If NSAIDs fail to relieve symptoms, doctors may recommend a biologic. These medicines target inflammatory proteins. The two main types for ankylosing spondylitis are tumor necrosis factor (TNF) blockers and interleukin-17 (IL-17) inhibitors.

TNF blockers include:

  • Adalimumab (Humira)

  • Certolizumab pegol (Cimzia)

  • Etanercept (Enbrel)

  • Golimumab (Simponi)

  • Infliximab (Remicade)

IL-17 inhibitors include:

If you cannot take a TNF blocker or IL-17 inhibitor, your doctor may recommend tofacitinib (Xeljanz). It is another kind of biologic with approval for treating psoriatic arthritis and rheumatoid arthritis. Researchers are studying it in ankylosing spondylitis.

In some cases, doctors may use disease-modifying antirheumatic drugs (DMARDs). They help control the disease process of ankylosing spondylitis. The most common DMARD used for this disease is sulfasalazine (Azulfidine).

In addition to medical treatment, physical therapy can be helpful. Surgery may be a last resort in cases of severe pain or joint damage.

What you can do to improve your ankylosing spondylitis

In addition to medications, you can also maximize your mobility and minimize stiffness by:

  • Exercising and remaining physically active

  • Practicing exercises to improve breathing and posture

  • Quitting smoking

  • Sleeping flat on your back

Complementary treatments

Complementary treatments may help some people to better deal with ankylosing spondylitis and its treatments. These treatments, sometimes called alternative therapies, are for use in conjunction with traditional medical treatments. They should not replace traditional medical care.

Be sure to notify your doctor if you are using nutritional supplements or homeopathic remedies. They may interact with the prescribed medical therapy.

Possible complementary treatments may include:

  • Acupuncture
  • Massage therapy
  • Nutritional dietary supplements, herbal remedies, tea beverages, and similar products
  • Yoga

How does ankylosing spondylitis affect quality of life?

Ankylosing spondylitis does not usually cause disability and it rarely causes complications. However, it can still have a significant impact on daily life.

Pain and stiffness can stop you from doing things you enjoy. Research has shown that quality of life decreases for people with ankylosing spondylitis. It tends to have the largest effect on physical well-being. However, it can also affect your mental health.

Predictors of reduced quality of life include higher disease activity and decreased spinal mobility. Fatigue and long symptom duration may also be associated with poorer physical and mental well-being.

Social and community support can be an important part of treatment. Talk with your doctor about resources that may be available in your area.

What are the potential complications of ankylosing spondylitis?

In rare cases, complications of untreated ankylosing spondylitis can be serious. You can help minimize your risk of serious complications by following the treatment plan you and your healthcare professional design specifically for you. Complications of ankylosing spondylitis include:

Was this helpful?
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 19
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