Ankylosing spondylitis is a type of arthritis of the spine. It causes swelling between your vertebrae, which are the disks that make up your spine, and in the joints between your spine and pelvis. Other conditions associated with AS include reactive arthritis, Reiter’s syndrome, psoriatic arthritis, spondylitis of inflammatory bowel disease, juvenile spondyloarthropathy and undifferentiated spondyarthropathy. Ankylosing spondylitis is an autoimmune disease. This means your immune system, which normally protects your body from infection, attacks your body's own tissues. It often runs in families.

Spondyloarthropathies include:

• Ankylosing spondylitis (AS): AS is a chronic, systemic, inflammatory disease of the joints and ligaments of the spine. Other joints may be involved. This typically results in pain and stiffness in the spine. The disease may be mild to severe. The bones of the spine may fuse (ankylosis) causing a rigid spine.

• Psoriatic arthritis: Psoriatic arthritis is a form of inflammatory arthritis that is associated with psoriasis of the skin. Psoriatic arthritis causes pain, stiffness, swelling and tenderness of the joints making movement of the joint(s) difficult. You can also get inflammation outside the joints such as at the tendon insertions called enthesitis, i.e. Achilles’ tendonitis. There is also a sausage like swelling of the fingers and toes known as dactylitis.

• Reactive arthritis (Reiter's syndrome): Reactive arthritis is a non-infectious inflammation of one or several joints. It may be self-limited, relapsing or chronic. The condition sometimes follows an infection of the gastrointestinal or genitourinary system. There may be other non-joint features such as eye, genital tract, bowel or skin inflammation.

• Enteropathic arthritis: Enteropathic arthritis is peripheral joint or spine disease associated with inflammatory bowel disease (IBD), such as Crohn's Disease or Ulcerative Colitis.  It is seen in up to 10 - 20% of those with IBD. It is more common in juveniles and young adults. The male to female ratio is equal.

• Juvenile spondyloarthropathy: Occurs in children with arthritis, more often in boys and almost always starts in the ankles, feet, knees, hips and other non-spinal joints.

• Undifferentiated spondyloarthropthy: Patients with features of more than one disease who do not fit in the defined categories above

General Features and Symptoms
Early symptoms include back pain and stiffness. These problems often start in late adolescence or early adulthood. Over time, ankylosing spondylitis can fuse your vertebrae together, limiting movement. Symptoms can worsen or improve or stop altogether. The disease currently has no cure, but medicines can relieve the pain, swelling and other symptoms to allow a normal and productive life. Exercise is very important in the management of ankylosing spondylitis.

The cause AS is unknown but genetics seems to play a role. A gene called HLA-B27 occurs in 90 percent of those with ankylosing spondylitis. Just because you have the gene, does not mean you will have ankylosing spondylitis. Other factors besides HLA-B27 are involved.

If your doctor suspects ankylosing spondylitis based on your history and symptoms, he or she can use a blood test for the HLA-B27 gene, an X-ray, or MRI of the sacroiliac joints to help make the diagnosis. The early signs of ankylosing spondylitis—dull low back and buttock pain and stiffness—are fairly common. If you have these symptoms for a period of time and they slowly increase, your doctor will ask about your pattern of symptoms and whether you have a family history of ankylosing spondylitis or similar joint disease. Some patients have eye inflammation (iritis).

Pain that moves around the low back area and changes in intensity, and morning stiffness that gets better once you start moving around or take a warm shower, are common symptoms of ankylosing spondylitis. (Pain occasionally starts in other areas, such as the hips or heels.) The clearest sign, however, is a change in the sacroiliac joints at the base of the low back. This change in the sacroiliac joints can take up to a few years to show on X-ray, which means doctors are often hesitant to give a diagnosis of ankylosing spondylitis until you have had symptoms for a long time.

Diagnosis
There is no direct test to diagnose AS. A drawback of X-ray diagnosis is that signs and symptoms of AS have usually been established as long as 8-10 years prior to X-ray evident changes occurring on a plain film X-ray, which can mean a long delay before adequate therapies can be introduced. The Schober's test is a useful clinical measure of flexion of the lumbar spine performed during examination.

During acute inflammatory periods, AS patients will usually show an increase in the blood concentration of C-reactive protein (CRP) and an increase in the erythrocyte sedimentation rate (ESR). Variations of the HLA-B gene increase the risk of developing ankylosing spondylitis, although it is not a diagnostic test. HLA-B27, demonstrated in a blood test, is occasionally used as a diagnostic, but does not distinguish AS from other diseases and is therefore not of real diagnostic value. Test  for rheumatoid factor (RhF) are typically negative.

The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), developed in Bath (UK), is an index designed to detect the inflammatory burden of active disease. The Bath Ankylosing Spondylitis Functional Index (BASFI) is a functional index which can accurately assess a patient's functional impairment due to the disease, as well as improvements following therapy. The BASFI is not used as a diagnostic tool, but as a tool to establish a patient's current baseline and subsequent response to therapy.

Scanning:

• X-ray film: Although radiographs are the single most important imaging technique for detection, diagnosis, and follow-up monitoring of patients with ankylosing spondylitis they are limited in detecting early sacroiliitis and showing subtle changes in the posterior elements of the vertebrae.

• Computerized tomography (CT or CAT): Useful in selected situations (eg, equivocal sacroiliitis and subtle radiographic changes) and in the evaluation of complications. Normal variations of the sacroiliac joints may simulate the findings of inflammation. CT is not ideal for imaging long segments of the spine because of its high radiation dose.

• Magnetic resonance imaging (MRI): Useful in assessing early cartilage abnormalities and bone marrow edema. However it has relatively poor ability to detect calcification, ossification, and cortical bony changes.

Pharmacotherapy options
Like many forms of arthritis, physical therapy and recreational exercise at least 30 minutes per day can significantly improve pain and stiffness. Additional back exercises at least five days per week will also improve pain and function in patients with ankylosing spondylitis.

There is also a vast array of drug treatment options for spondyloarthropathy, starting with nonsteroidal anti-inflammatory drugs (NSAIDs), such as indomethacin, naproxen, ibuprofen, diclofenac or the COX-2 inhibitor, celebrex can cause relief of disease  symptoms. Although no one specific NSAID is considered superior to another for spondyloarthritis patients, indomethacin may have superior activity.

Disease modifying anti-rheumatic drugs (DMARDs) such as sulfasalazine (effective in peripheral and axial symptoms) and methotrexate (has been proven to be more effective in treating accompanying arthritis in the arms or legs, but not for arthritis of the spine or sacroiliac joints).

Corticosteroids taken by mouth also can be effective. However, given their side effects, particularly osteoporosis and infections, and new agents now available (see below), these medications are not recommended unless the more effective treatments cannot be used. Injections of depo-steroid medications into joints or tendon sheaths are frequently used by clinicians for symptomatic relief of local flares.

Antibiotics such as ciprofloxacin, given over a three-month course soon after disease onset, may have a beneficial effect on the prognosis of reactive arthritis, especially when triggered by Chlamydia trachomatis, but not in other types of spondyloarthritis.

TNF alpha blockers (also known as biologics) have been shown to be quite effective in treating both the spinal and peripheral joint symptoms of spondyloarthritis, as well as other problems such as psoriasis and intestinal inflammation. There are three types currently available:

• Infliximab (Remicade), which is used at a dose of 5 mg/kg given intravenously every six to eight weeks

• Etanercept (Enbrel), given 25 mg under the skin twice weekly

• Adalimumab (Humira), injected at a done of 40 mg. every other week under the skin

However, anti-TNF treatment is expensive and not without complications, including an increased risk for infections, especially tuberculosis. Therefore, NSAID and DMARD therapy are tried first.

Non-Pharmacotherapy options
Physical therapy includes exercises to maintion flexibility and prevent a stooped posture and breathing problems if the spine starts to fuse and ribs are affected. Back braces may be used to prevent continued deformity of the spine and ribs.

Only in severe cases of deformity is surgery performed to straighten and realign the spine, or to replace knee, shoulder, or hip joints. Patients with spondylitis are at increased risk for vertebral fracture, they may experience often spinal cord damage. Typically, these patients must wear a kind of brace called a “halo vest.” Surgical spinal fusion may be necessary when spinal cord or nerve function is compromised.

Some patients seek surgical correction of the spinal deformities that can occur with ankylosing spondylitis, called osteotomy. Given the extensive complication rates, patients considering this procedure should consult surgeons experienced with this type of operation.