Ankylosing spondylitis (AS) is a chronic inflammatory form of arthritis that affects the spinal joints. The hallmark feature of AS is the involvement of the joints at the base of the spine where the spine joins the pelvis - the sacroiliac (SI) joints.

The disease course is highly variable, and while some individuals have episodes of transient back pain only, others have more chronic severe back pain that leads to differing degrees of spinal stiffness over time. In almost all cases the disease is characterized by acute painful episodes and remissions (periods where the problem settles).

Over the years AS has been known by many different names including poker back, rheumatoid spondylitis, and Marie-Strumpells spondylitis. Since the early 70s with increasing knowledge about the disease, there is almost universal use of the term ankylosing spondylitis (AS).

AS is a member of the family of diseases that attack the spine. These are named spondylarthropathies. In addition to AS, these diseases include Reiter’s syndrome, some cases of psoriatic arthritis and the arthritis of inflammatory bowel disease.

AS is three times more common in men than in women. It typically affects young people, beginning between the ages of 15 and 30. It may affect younger people also, although in very young people it may take a slightly different form, causing pain around the heels, knees, and hips rather than beginning with the spine. Onset after age 40 is uncommon.

The most universal symptom of AS is chronic low back pain that seems to just come on for no apparent reason. The pain is typically worse in the morning. On rising from bed, people with AS may feel stiff and sore and this may take anywhere from 30 minutes to several hours to pass off.

The back pain is usually dull and diffuse rather than sharp and localised. The most common site of pain is deep within the buttock, on one side, or on both sides. In addition to the buttock, there could be pain further up the back, perhaps between the shoulder blades or in the neck.

In a lesser number of individuals, pain does not begin in the spine but starts in a hip, knee or shoulder joint. This can be confusing when there is no back pain present and may initially look like some other form of arthritis.

The pain of AS results from inflammation of the joints. When inflammation is present, the involved area hurts. To avoid the pain there is a natural tendency to stoop forward as extending backwards is more uncomfortable. This reflex can lead to bad posture. Also in bed there is a tendency to curl up, as this may feel more comfortable.

If the inflammation associated with AS continues unchecked, it can produce changes within the spinal column. Small bony outgrowths extend from the edges of the vertebrae and can eventually bridge across from one vertebra to the next. Should this occur, over time it can result in stiffness and immobility between the vertebrae. While there are 24 different spinal vertebrae in the back, stiffness of any two can limit function. Stiffness of more can lead to progressive disability.

While spinal stiffness is to be avoided, even greater potential disability can occur if AS affects the hips, knees or shoulders. The hip joints are quite often involved and can progress to where the joint is damaged, becoming limited in mobility, and painful. The end stage of this hip damage is frequently total hip joint replacement.

Joints Affected
Most commonly the joints in the buttocks, called the sacroiliac joints, are affected. The low back is commonly involved, as is the mid-back (the thoracic spine) and the neck (the cervical spine).

Of the non-spinal joints, the hips are the most commonly involved and to a lesser extent the knees and shoulders. Involvement of the small joints of the hands and feet, wrists and ankles is unusual.

The joints between the ribs and the spine and between the ribs and the breast bone (sternum) can also become painful and stiff. Stiffness of these joints can result in decreased chest expansion.

Iritis (Inflammation of the Iris of the Eye)
Individuals with AS have a much greater likelihood of having episodes of iritis (inflammation of the iris of the eye). This results in the eye being painful and irritated. It is often described as a feeling of having had a handful of sand thrown in the eye. The individual may also be sensitive to bright light. This is usually treated with eye drops.

Aortitis
Although it is relatively uncommon, there is a possibility of inflammation involving the aorta near the heart. If you have AS, your physician may therefore listen to your heart from time to time.

AS tends to run in families. Just as we inherit our hair colour and blood type from our parents, we also inherit our tissue type. The tissue typing system is the Human Lymphocyte Antigen (HLA) system. One of the tissue types, HLA-B27, is found in only 6% of the broad population but occurs in approximately 93% of individuals with AS.

The HLA-B27 tissue type, while not causing AS, does predispose individuals with the B27 tissue type to developing AS. Thus we see AS tending to occur in families. Having the tissue type itself does not mean you will get AS, it simply increases the possibility. Identifying the activating agent that later triggers AS is the focus of much current research. There is discussion among researchers that other genes in the immune system may also lead to the development of AS, perhaps by interacting with some environmental factor.

Diagnosis is made from several different features. The history of the onset of pain, the areas of involvement, and the times of the day when pain is worst, are key. In young people the presence of tender points at specific locations around the feet, heels, knees and hips can be indicative of AS. Since AS often affects young, active males, it is sometimes misdiagnosed as mechanical low back strain.

The most classic site of involvement is the sacroiliac (SI) joints on the right and/or left sides in the buttock area. Unfortunately, X-ray evidence of changes in the SI joints may take some time to occur, thus an X-ray taken in the early years of the problem may be negative. Over time the SI joints will usually show changes that can be seen on X-ray. In addition to the SI joint x-ray changes, changes at the edges of some vertebrae may be observed.

There is no blood test that diagnoses AS specifically, but blood tests may be done that could contribute to the picture. Your doctor may choose to perform a blood test called ESR (erythrocyte sedimentation rate) which shows whether or not inflammation is present in the body. This test can help determine if your pain is caused by inflammation or by something else.

Your doctor might also test for the HLA-B27 blood group to help diagnose the disease early, however the presence of HLA-B27 does not directly indicate that you have AS. X-rays may be taken to determine if there is evidence of change to the joints at the bottom of the spine (sacroiliac joints). However, changes in these joints occur slowly over time and may not be present in early stages of the disease.

Often, precise measurements are made of the mobility of the spine and this can also contribute to the diagnosis. By the time spinal joints become markedly stiff, however, the disease has usually been present for some time.

A variety of treatments can help to lessen pain and stiffness and make movement easier. Your active involvement in developing your prescribed treatment plan is essential.

Medications

Nonsteroidal anti-inflammatory drugs (NSAIDs)
NSAIDs reduce pain when taken at a low dose, and relieve inflammation when taken at a higher dose. NSAIDs such as ASA (Aspirin, Anacin, etc.) and ibuprofen (Motrin IB, Advil, etc.) can be purchased without a prescription. Examples of other NSAIDs that require a prescription include Naprosyn, Relafen, Indocid, Voltaren, Feldene, and Clinoril. The various NSAIDs and Aspirin®, if taken in full doses, usually have the same levels of anti-inflammatory effect. However, different individuals may experience greater relief from one medication than another. Taking more than one NSAID at a time increases the possibility of side effects, particularly stomach problems such as heartburn, ulcers and bleeding. People taking these medications should consider taking something to protect the stomach, such as misoprostol (Cytotec).

Disease-modifying anti-rheumatic drugs (DMARDs)
Disease modifying anti-rheumatic drugs (DMARDs) are often prescribed to relieve severe symptoms of ankylosing spondylitis. These medications are designed to prevent AS from getting worse, but do not reverse permanent joint damage. It will usually take several months for DMARDs to make a noticeable improvement in the inflammation.

The Cochrane Musculoskeletal Review Group (CMSG) is a specialized group of researchers and consumer representatives that belong to the Cochrane Collaboration, an international not-for-profit organization that encourages informed decisions about health care by preparing, maintaining and promoting reviews of the effects of various health care treatments.

CMSG members review the best available literature to determine the best evidence to support specific arthritis treatments. They explore the evidence for and against the effectiveness and appropriateness of treatments (medications, surgery, education, etc) in specific circumstances. The results are medical reviews that are then included in The Cochrane Library and made available to health professionals around the world.

For members of the public who also want to be informed about the evidence concerning health care practices and decisions in their lives, the Cochrane Musculosketal Review Group have summarized their reviews into consumer fact sheets. For the Cochrane consumer reviews related to ankylosing spondylitis, visit www.arthritis.ca/cochrane.

While the course of AS varies, most people do well and continue to live normal but sometime modified lives.

Those with very heavy jobs requiring a lot of bending and lifting may have to consider an alternative.

Along with the physical symptoms of arthritis, many people experience feelings of helplessness and depression. Learning daily living strategies to manage your arthritis gives you a greater feeling of control and a more positive outlook. To get the best results, people affected by arthritis need to form close ties with their doctors and therapists, and become full partners in their treatment. From our perspective, it's all part of 'living well with arthritis.' There are several resources you can use in finding out how best to manage your own arthritis. Here are a few:

• The Arthritis Self-Management Program (ASMP) is a unique self-help program offered by The Arthritis Society to help you better control and manage your arthritis.
• The Open Forum within this Web site is an opportunity to discuss and share information with other visitors - people who, through their own experiences, may be able to offer some useful insights.

Of course, there are many other valuable resources for people with arthritis. If you're unclear about where to look for help, be sure to call The Arthritis Society at 1.800.321.1433.