A Patient's Guide to Ankylosing Spondylitis


Ankylosing Spondylitis (AS) is a type of progressive arthritis that leads to chronic inflammation of the spine and sacroiliac joints. It can also affect other joints and organs in the body, such as the eyes, lungs, kidneys, shoulders, knees, hips, heart, and ankles. However, AS primarily affects the axial skeleton, including the ligaments and joints.

This disease causes stiffness, aching, and pain around the spine and pelvis. The disease can eventually lead to a total fusion of the spine. This occurs when the vertebrae (spinal bones) actually grow together fusing the spine due to calcification of the ligaments and discs between each vertebrae. If the vertebrae fuse together, the spine is robbed of mobility, leaving the vertebrae brittle and vulnerable to fractures.

You may also see AS referred to as a seronegative spondyloarthropathy. What this means is that you may have all the symptoms of AS, but you do not have the positive blood test that usually goes along with this type of arthritis. The test that is negative is called the rheumatoid factor. This is simply a way for doctors to classify AS in relation to other forms of arthritis that affect the entire body.

An easy way to understand what AS does to the body is to look at the words ankylosing and spondylitis. Ankylosing means stiffening; it comes from the Greek word "angkylos", which means bent. Spondylitis means inflammation of the spine; it comes from the Greek word "spondylos", meaning spinal vertebrae. In essence, the disease causes your spine to stiffen because of inflammation of the joints. This can cause the vertebrae to fuse together. It may also cause a kyphosis of the spine, which gives your spine a forward curve.

AS affects primarily younger adult males. In fact, this disease is about nine times more common in males than females. This disease is also around three times more common in Caucasians than African Americans. Although AS can strike people of any age, race, or sex, the onset is most common in men between the ages of 17 and 35. In women, the symptoms of AS often first appear during pregnancy.

Another unique feature of AS is that it appears to be genetic. A specific gene, called the HLA-B27 gene, is present in many people who have the disease. Eighty to ninety-five percent of people who have AS also have the HLA-B27 gene. This does not mean that if you have the gene you will automatically get AS. In fact, even though around eight percent of Americans have this gene, only about one percent actually has ankylosing spondylitis. However, if you are suspected of having AS, a blood test to determine if you have the HLA-B27 is useful. In the early stages of AS, it is sometimes hard to make a definite diagnosis. If you have the symptoms of AS AND you have the HLA-B27 gene, it is likely that the diagnosis of AS is correct.

This website will offer you valuable information about the following:

  • Anatomy of AS
  • Causes of AS
  • Symptoms
  • Diagnosis
  • Treatment Options

Anatomy of AS

The first sign of AS, inflammation, is initially found in the sacroiliac joints. The sacroiliac joints are the two joints that connect the spine with the pelvis. You can feel these joints about three inches to the side of the spine in the area of the low back. The inflammation next moves to the spine. Long-term inflammation of the spinal joints (spondylitis) leads to calcium deposits forming in the ligaments around the invertebral discs (the cushions between your spinal vertebrae) and the ligaments that hold the vertebrae together. When the ligaments calcify, movement is restricted. Eventually there can be a complete fusing together of the vertebrae (ankylosis).

A healthy spine is able to move in many directions, which is why you can bend, turn, and twist. The spinal bones are joined together by flexible ligaments and are separated by cushiony discs, which allow for lots of movement. However, if the ligaments calcify, the bones can fuse together and make movement impossible. This is why AS can be disabling in its advanced stages.

AS inflammation can also affect other joints and organs in your body. It is a true "systemic disease", meaning the problem is not simply a problem with one joint or one organ. It involves changes throughout the body. We will be dealing mostly with the problems that affect the skeleton in this document.

Causes of AS

Though the origin of AS is still unknown, we do know a lot about how it progresses and why it causes spinal stiffening.

When AS first appears, an inflammation of the bones (called osteitis) occurs around the edges of the joints. In these areas, special cells that are called inflammatory cells begin to increase in number. These inflammatory cells produce chemicals that damage the bone causing it to begin to dissolve and weaken around the edge of each joint. The damage to the bone in this area starts a process where the body continuously tries to repair the damage with scar tissue and new bone tissue. As the process continues, the bone becomes weaker and weaker. When the inflammation finally "burns out" and begins to disappear, the body responds by producing calcium deposits around the area of the damage, attempting to heal the bone.

As the bone heals itself, the calcium deposits spread to the ligaments and discs between the vertebrae as well, for some unclear reason. This is what leads to a fusion of the spine (sometimes referred to as bony ankylosis).


Like other forms of arthritis, the symptoms of AS are from the effects of inflammation: pain, stiffness, and loss of mobility.

  • Usually the first sign of AS is sacroiliitis. The sacroiliac joints are the part of your low back where the bone above your tailbone (sacrum) meets the bones on both sides of your buttocks (iliac). When these joints are inflamed, it is called sacroiliitis. Sacroiliitis causes pain in the low back and buttock areas.
  • At the onset of AS, there is often severe low back pain, buttock, hip, and thigh pain on one or both sides. The onset is usually gradual, growing progressively worse with time.

  • Initially the symptoms may come and go for weeks or months at a time.

  • Another symptom of AS is stiffness and low back pain in the morning, which usually improves with activity as the day progresses.

  • With AS, prolonged rest worsens the symptoms, as opposed to some other forms of low back pain where rest is helpful.

  • In the mid-portion of the spine (called the thoracic spine), AS will only affect the joints where the ribs connect to the vertebrae (these are called the costotransverse and costovertebral joints). The pain from inflammation in these joints can be felt in the chest wall and into the abdomen.

  • AS causes a reduction in the flexibility of the spine. This can affect your ability to bend forward and backward.

  • Symptoms in the neck (the cervical spine) include: stiffness, pain, and limited motion.

  • Because AS attacks the joints of the body, synovitis is often another sign of AS. Synovitis is a term used to describe inflammation of the synovial membrane. The synovial membrane is the material that forms the inside of each joint in the body. All joints can be affected. This may show up as pain, stiffness, and swelling of any joint in the body.

  • AS can affect your breathing as it progresses. The forward curve of the thoracic spine can become greater and greater. This deformity is called a kyphosis. When this occurs, it becomes increasingly difficult to take a full breath in; the chest simply cannot expand enough to breath deeply. AS can also lead to actual inflammation of the lungs, which makes breathing even more difficult.

  • AS can affect the eyes. Iritis is a condition that is caused by inflammation of the iris in your eye. The iris is the colored part of your eye around the pupil. This condition will cause pain and redness in the eye, however vision is usually not impaired. This disorder is found in 25 percent of AS patients.

  • When AS progresses, the spine pain may disappear. However, this does not signal a remission of the disease. When the spine becomes completely fused together, the pain in the spinal area usually goes away, but you are left with no spinal mobility and brittle bones that are more likely to fracture. If pain suddenly reappears in the back after a long period of no pain, you may have fractured a vertebra.


There are several things that your health care provider will do to try to make the diagnosis of AS. These include: a history and physical examination, X-rays, and laboratory tests.


Certain things may make your health care provider consider AS a possible diagnosis, including:

  • Onset of back pain before age 35-40
  • Gradual onset; not caused by a trauma
  • Pain that has lasted more than three to six months
  • Improvement with exercise and motion
  • Spinal stiffness in the mornings
  • Family history of AS


If AS is suspected, your doctor may order X-rays to look for signs in the pelvis and spine. One common sign visible on X-rays is vertebral bodies that have become deformed into an abnormal square shape. Doctors refer to this finding as a "bamboo spine" appearance. It gives the spine a very symmetrical and segmented appearance on the X-ray.

Most of the early X-ray findings will be seen around your sacroiliac joint (SI joint) and they are usually seen on both sides. These signs include: patchy osteoporosis (loss of bone mass), poorly defined joint margins, a widening of the SI joint space, and erosions of the joint. In advanced cases of AS, the X-rays will show many changes including: calcium deposits in the ligaments and discs, complete spinal fusion, and perhaps old spinal fractures.

Laboratory tests

There is not a blood test to determine if you have AS. However, the presence of the HLA-B27 gene in your blood does make the likelihood of the diagnosis more probable. Remember, eighty to ninety-five percent of AS patients have this gene.

Your blood can also be tested for evidence of increased inflammation in the body. The test normally used for this is the Erythrocyte Sedimentation Rate (ESR). This test is a simple gauge of inflammation in the blood from any cause. Even a common cold will increase this test significantly.

Your kidneys may also be tested through a urinalysis. This is done to look for possible kidney abnormalities that could be causing problems with similar AS symptoms.

Treatment Options

There is not yet a cure for AS. However, there are effective treatment options that can relieve pain and improve your condition.

The general approach is a conservative treatment plan that includes: medication, physical therapy, and exercise. Surgery may be necessary at some point to treat problems caused by AS in the spine and other joints of the body.


Your doctor will suggest medications that are used to reduce inflammation and pain. The most common are NSAIDs (non-steroidal anti-inflammatory drugs), particularly indomethacin. It is best to take such medications as prescribed by your doctor, and to take them with food to ward off side effects. Possible side effects include nausea, stomach upset, diarrhea, and abdominal pain.

If the NSAIDs are not reducing the inflammation sufficiently, the medication, sulfasalazine, may also be suggested. Corticosteroids, such as prednisone, are very effective at reducing inflammation, but their side effects can be serious if taken on a long-term basis.

If anti-inflammatory medications do not control the pain and inflammation sufficiently, there are medications available that block the immune system of the body and can reduce inflammation. These medications have many side effects and must be monitored closely.

Overall, NSAIDS are the preferred treatment choice if they are effective for the patient.

Physical Therapy

Physical therapy is an important part of treating AS. Movement will help return mobility to the spine and may improve your posture. A well-designed exercise program can also provide pain relief in most AS patients. A physical therapist will develop an appropriate exercise routine for your case. It is essential that you stick to the plan.

Typical advice includes:

  • Learning correct body mechanics to maintain erect posture that counteracts the affects of kyphosis (the forward curve of the spine)
  • Not using a pillow when you sleep, again to help prevent kyphosis
  • Doing regular non-jarring exercises, such as swimming
  • Maintaining high levels of activity
  • Doing daily stretching exercises and deep breathing (for lung expansion)
  • Avoiding prolonged bed rest and sitting


Surgical intervention is uncommon with AS. It is only necessary if the disease has led to severe deformity, such as extreme kyphosis that prevents standing and looking forward. In this case, a spinal osteotomy might be considered. This operation involves cutting through the spinal bones and realigning them into a position that allows the patient to stand and look forward. The spinal cord is not cut, only the vertebrae.

Surgery may also be recommended if the hip joints have been affected by the arthritis associated with AS. If the hips become severely damaged by arthritis, an artificial hip replacement may be required. This is a fairly common surgical procedure for patients with AS.

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