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Ankylosing Spondylitis: An Overview


Ankylosing Spondylitis (AS) is an inflammatory condition which especially involves the spine, but which can also affect multiple other joints, such as the hips, knees, and chest. The severity and pattern of joint involvement varies from person to person.

Genetics play a large role in this condition; over 90% of those with ankylosing spondylitis have a particular marker that can be found on their white blood cells, called HLA-B27. This means that a number of people with AS will have a family history of the condition, although it may be much more painful and involve more areas of the body in one family member than another. Many people with AS will not be able to identify anyone else in their family with the condition, however, since only about 20% of those with HLA-B27 will experience inflammatory conditions such as AS.

Ankylosing spondylitis often begins at a young age (from the teens to the third decade of life) and is more common in men (about 2-3 times more common than in women). AS can also present as juvenile ankylosing spondylitis, more commonly in boys than girls.

The most common symptom of ankylosing spondylitis is low back and/or neck pain, morning stiffness, and limited motion, which is improved by exercise and unrelieved by periods of rest. Joint pain in the hips, shoulders, knees, chest wall, or other areas is the next most common symptom. Eye inflammation (uveitis) can occur in this condition, and regular ophthalmology checkups are important, since eye damage can occur even before a person feels any symptoms. Heart and lung problems can also be associated with AS, but are fortunately less common.

Ankylosing” refers to the tendency of the spine to fuse, due to inflammation of the ligaments that attach one vertebral body to another. (See Fig. 1)

An "ankylosed" spine seen from the front   An "ankylosed" spine seen from the side
CLICK to enlarge images
Fig. 1: An "ankylosed" spine seen from the front and side

Spondylitis” refers specifically to the inflammatory process (“itis”) of the spine. As a result of this inflammation, a person feels stiffness and pain in the back, a gradual loss of mobility, and in the more severe cases, essentially complete loss of motion of the lower back. The neck (cervical spine) often has a similar inflammatory process and can likewise progressively lose motion.

It is very important to have an early diagnosis for ankylosing spondylitis, since treatment is needed even for mild and early cases. All patients with AS need to get involved in a physical therapy regimen as soon as possible, and a significant number need strong medications to quiet the inflammation and keep them functional.


As discussed above, the HLA-B27 gene appears to play a role in over 90% of cases of ankylosing spondylitis. However, simply having the gene does not seem to be enough to determine who gets the disease, as evidenced by the 80% of people with this genetic marker who avoid developing inflammatory disease. Some environmental factor, as yet not determined (and likely there are more than one factor), clearly plays a role in determining which people with this genetic makeup end up with AS.

People with the HLA-B27 genetic marker can develop other types of inflammatory conditions other than ankylosing spondylitis, such as eye inflammation with no arthritis. Rheumatologists only order testing for this genetic marker occasionally, since just finding that you have the marker doesn't confirm any diagnosis. Diagnosing AS is really a matter of medical history, physical exam, and x-ray studies, more than any blood test.


Symptoms of ankylosing spondylitis vary from patient to patient, but they most commonly begin with the onset of low back pain and stiffness that is especially noticeable in the morning hours and after long periods of rest. This pain is usually relieved by physical activity and improves by the end of the day. Some patients experience similar pain in the buttocks, hips, chest, upper back, and neck. If left untreated, the ankylosing process can result in a "hunchback" appearance.

Patients are also prone to an onset of arthritis in the large joints and elsewhere, and can – in some cases - experience heel pain related to Achilles tendonitis, lung problems (as a result of lung scarring and spinal inflammation, limiting chest expansion), aortitis (inflammation of the aortic valve and the large artery - the aorta - coming from the left side of the heart), and iritis (a form of uveitis, or inflammation of the pigmented part of the eye), which can lead to visual loss and glaucoma.


The difficulty of diagnosing ankylosing spondylitis lies in differentiating its symptoms from those of other forms of low back pain. In order to make this distinction, a combination of diagnostic measures are required, including a physical exam, imaging studies, and laboratory tests.

Imaging studies include x-rays and, if necessary for more detailed evaluation, CT exams or MRI scanning. Lab tests are employed to detect signs of an inflammatory process (for example, the sedimentation rate may be elevated as a sign of inflammation in AS). On occasion, a blood test for the HLA-B27 gene marker will be ordered, but the diagnosis is more often made based on history and exam, since simply having the HLA-B27 gene marker does not diagnose AS or any other condition (and most people who have this gene marker are healthy and disease-free).


Early diagnosis is very important with ankylosing spondylitis. As with most other inflammatory types of arthritis, there is no cure at present for AS. Fortunately, however, medication and physical therapy treatment can usually make a dramatic difference in a person’s symptoms and function. In addition to these options, local steroid injections can help, and patients with especially severe disease can at times be helped greatly with surgical procedures.

Physical Therapy & Exercise

It’s essential for all ankylosing spondylitis patients to engage in physical therapy and home exercise program, and to strive for proper maintenance of posture to help maintain maximum possible flexibility. AS stiffens the spine and tends to position the head to be held forward and the lower back to remain in a flexed position. Stretching and exercise regimens aim to oppose these tendencies and to increase flexibility.

Since the lungs can be affected in AS - both by scarring due to inflammation and by decreased chest expansion due to chest wall inflammation - breathing exercises are important. This can help patients with AS maintain their exercise tolerance. It is also important for this reason for AS patients to stay away from smoking tobacco.


While medications can’t turn back time and make the disease regress, they can be tremendously helpful in relieving pain, restoring mobility, and - as appears to be the case with newer medications called anti-TNF agents - slowing and/or stopping the progression of the disease in its tracks.

There has been excellent evidence that anti-TNF agents can provide marked functional improvement, and these are used in many patients with more serious disease. These anti-TNF agents - including infliximab, etanercept, adalimumab, golimumab and certolizumab – improve mobility while alleviating pain. Ongoing study is needed to determine the long-term ability of these agents to prevent fusion of the spine.

While nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin, naproxen, celecoxib, piroxicam, sulindac, and tolmetin haven’t been shown to affect the tendency of the spine to fuse, they work similarly to reduce inflammation, stiffness, and the resulting pain in many patients with AS. There is also a role for pain killers, such as acetaminophen or codeine, when needed.

For patients with AS and arthritis of the hip or knee, for example, local steroid injections can help with pain and stiffness.

Patients with AS, due to decreased mobility and inflammation, are at increased risk of osteoporosis. They should have their bone density evaluated and treated if it is low.


Surgery is usually considered when AS has progressed to a point at which the patient’s mobility is severely impaired due to chronic, debilitating pain or a painful deformity. The great majority of patients with AS never need surgery. For those who do, several procedures are available.

The nature of the surgery will depend on the degree of deformity, whether or not the bony changes are causing any pressure on nerves, and the stability of the spine. The procedures will generally involve an osteotomy, which refers to the removal of some of the bone and realignment of the spine; instrumentation and fusion are generally used to allow the bone to heal in a stable position.

The type of surgery will depend upon the specific case and the judgment of the surgeon.


As is true for all types of inflammatory arthritis, ankylosing spondylitis progresses differently on a patient-by-patient basis, and symptoms will vary accordingly. In some patients, the hardening of the spine occurs at a faster rate, while others will experience only slight inflammation and pain, and little loss of function.

Again, in common with other types of inflammatory arthritis, ankylosing spondylitis is not presently curable, but very effective treatments exist. Non-steroidal anti-inflammatory agents (such as indomethacin or naproxen) can be extremely helpful, and pain killers without anti-inflammatory properties (e.g. acetaminophen) can also help. The anti-TNF medications clearly often provide dramatic improvements in function and may prove effective in halting the disease in the long term. Surgery is an option for those with advanced, debilitating forms of the disease.

Regardless of the medications used in the individual case, the importance of exercise and physical therapy cannot be overstated.

The outlook for patients with ankylosing spondylitis is much better today than it was 15 years ago. It is very important for AS to be diagnosed as early as possible, before the spine has a chance to fuse. If a person with AS is faithful to their exercise and physical therapy program, and works with their rheumatologist to develop a medication regimen that is right for them, their chances of a highly-functional long-term outcome are excellent.


Headshot of Theodore R. Fields, MD, FACP
Theodore R. Fields, MD, FACP
Attending Physician, Hospital for Special Surgery
Professor of Clinical Medicine, Weill Cornell Medical College

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