What is Ankylosing Spondylitis?

What you need to know about Spondyloarthritides

Spondyloarthritides are a group of arthritic diseases that share several common features. They can cause inflammation of the spine; however, other joints may be affected. The tendon and ligament tissue near the spine or joint is also involved. A high percentage of people with these diseases share a similar gene called HLA B27. Finally, many patients also have inflamed areas in the eye, bowel, genital tract or skin.

The spondyloarthropathies include:

  • Ankylosing spondylitis
  • Psoriatic arthritis
  • Reactive arthritis/Reiter's syndrome
  • Enteropathic arthritis
  • Undifferentiated: Patients with features of more than one disease who do not fit in the defined categories above

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 over time causing a rigid spine. Early diagnosis and treatment may help control the symptoms and reduce debility and deformity.

Who gets ankylosing spondylitis (AS)?

The onset is typically in late adolescence to early adulthood. It is rare for AS to begin after age 45. The disease is more common in men and in Caucasians. The incidence is 1 in 1000 persons. About 90% of people with AS have the HLA B27 gene.

What causes ankylosing spondylitis (AS)?

The cause of AS is unknown although there appears to be some genetic component. AS is associated with the HLA B27 gene but it is unclear why. The gene is seen in about 8% of normal Caucasians. There are no known infectious or environmental causes.

What are the signs and symptoms?

Early on, there is pain and stiffness in the buttocks and low back due to sacroiliac joint involvement. Over time, the symptoms can progress up the spine to involve the low back, chest and neck. Ultimately, the bones may fuse together causing limited range of motion of the spine and limiting one's mobility. Shoulders, hips and sometimes other joints may be involved. AS may affect tendons and ligaments. For example, the heel may be involved with Achilles tendonitis and plantar fasciitis. Since it is a systemic disease, patients can get fever and fatigue, eye or bowel inflammation, and rarely, there can be heart or lung involvement. AS is typically non life-threatening. Usually, it is a slowly progressive disease. Most people are able to work and function normally.

How is ankylosing spondylitis (AS) diagnosed?

The diagnosis is typically suspected by the doctor based on the signs and symptoms. The doctor will take a thorough history and do a physical examination. X-rays, especially those of the sacroiliac joints and spine can be confirmatory. The HLA B27 gene may be checked by a blood test, but its presence or absence does not ultimately confirm or reject the diagnosis.

How is ankylosing spondylitis (AS) treated?

At this time there is no known curative treatment. Goals of treatment are to reduce pain and stiffness, slow progression of disease, prevent deformity, maintain posture and preserve function.

Exercise programs are an essential part of the treatment. Patients may be referred for a formal physical therapy program. Patients with AS are given daily exercises for stretching and strengthening, deep breathing exercises and posture exercises to avoid stooping and slumping.

Medications are also used to treat AS. Non-steroidal anti-inflammatory drugs (NSAIDs) are traditionally used to control symptoms. Steroids, such as cortisone or prednisone, are rarely used, except for with injections to a tendon or joint. Sometimes, medications that are normally used for rheumatoid arthritis, such as sulfasalazine or methotrexate, may be used. These appear to be less helpful for the spine disease. More recently, the biologic anti-TNF-a agents etanercept (Enbrel®), adalimumab (Humira®), and infliximab (Remicade®) have been approved for use in AS. These drugs may not only help symptoms but also slow the progression of the disease. They are only given as IV's in the doctor's office or by self-administered shots at home.

Surgical options are limited. There are no specific surgical interventions for the spine. Sometimes, in severe cases, replacement of the shoulder or hip joint is beneficial.

Reactive arthritis (ReA)

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.

The term Reiter's Syndrome is an older term that most rheumatologists have now replaced with Reactive Arthritis. Reiter's Syndrome was a term originally used to refer to a syndrome of non-infectious eye, genital and joint inflammation following a previous bowel or genital bacterial infection. All of these features are rarely seen together.

Who gets reactive arthritis?

ReA may follow an infection of the genital tract or bowel, but this is not always identified. It is more common in men and Caucasians. ReA is rare after the age of 50. The disease is associated with the HLA B27 gene in 50 - 80% of patients.

What causes reactive arthritis?

The cause of ReA is unknown. It is associated with the HLA B27 gene, but it is unclear why. It is also unclear why ReA is sometimes associated with infection. (Bacterial infections of genital tract with Chlamydia or gastrointestinal tract with Shigella, Salmonella, or Campylobacter).

What are the signs and symptoms of reactive arthritis?

ReA may follow several weeks after a genital tract or bowel infection. The patient may have acute swelling, pain and redness in one or more joints. Typically, it is more common in the lower extremity joints. During the joint symptoms, one may also have non-infectious genital tract, skin or eye inflammation. ReA patients may have tendonitis, especially of the heel. There may be spine involvement (like ankylosing spondylitis). Traditionally, ReA is self-limited to 3 to 12 months, but up to 50% may have relapsing or chronic disease. The disease is not life threatening, and most people are able to work and function normally.

How is reactive arthritis diagnosed?

The diagnosis is typically made by a doctor taking a thorough history and physical examination. A swollen joint may be aspirated to rule out an infection or gout. There is no specific test for the diagnosis of ReA. The HLA B27 gene may be checked by blood test in selected cases, but it is not diagnostic.

How is reactive arthritis treated?

At this time, there is no curative treatment. Any existing infection, if discovered, should be treated. The role of routine antibiotics is controversial. Physical therapy, stretching and exercise are prescribed. Non-steroidal anti-inflammatory drugs (NSAIDs) are given for pain and stiffness. Steroid injections to involved tendons or joints can help relieve pain and inflammation. In chronic or relapsing cases, similar treatments to rheumatoid arthritis can be considered to include methotrexate, sulfasalazine and the biologic anti-TNF-a drugs (as listed for AS).

Enteropathic arthritis

Enteropathic arthritis is peripheral joint or spine disease associated with inflammatory bowel disease (IBD), such as Crohn's Disease or Ulcerative Colitis.

Who gets enteropathic arthritis?

Enteropathic arthritis 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.

What causes enteropathic arthritis?

The cause is unknown.

What are the signs and symptoms of enteropathic arthritis?

The arthritis typically occurs after the bowel disease is well established. Rarely, the arthritis can start before IBD is diagnosed. There is pain and swelling in one or more joints. Typically, the arthritis occurs in the lower extremity joints. The arthritis may mirror the activity of the bowel disease. There may also be spine involvement (like ankylosing spondylitis). The HLA B27 gene is seen in up to 50% with spine involvement. The spondylitis (spine involvement) is less likely to correlate with the bowel disease activity. Patients may have other systemic symptoms such as fever, skin or eye inflammation, and oral ulcers. Enteropathic arthritis rarely causes joint destruction, deformity or significant disability.

How is enteropathic arthritis treated?

Like the other spondyloarthropathies, the patient needs physical therapy and exercise. Treatment of the bowel disease may help the peripheral joints but not the spine. Removing the colon (colectomy) in ulcerative colitis may "cure" the arthritis. One can use non-steroidal anti-inflammatory drugs (NSAIDs), but there is a need to be aware of the bowel effects. Local injection of steroids into joint(s) can be very helpful. Oral steroids can be used in more severe cases. In resistant cases, medications normally used to treat rheumatoid arthritis, such as methotrexate, azathioprine (Imuran®) or sulfasalazine can be tried for the joints. Anti-TNF-a drugs, like adalimumab (Humira®) and infliximab (Remicade®) have shown benefit with joint and bowel disease.


  • Woods RP, Seamon J. Chapter 21. Arthritis & Back Pain. In: Stone C, Humphries RL. eds. CURRENT Diagnosis & Treatment Emergency Medicine, 7e. New York, NY: McGraw-Hill; 2011.
  • Burton JH. Chapter 281. Acute Disorders of the Joints and Bursae. In: Tintinalli JE, Stapczynski J, Ma O, Cline DM, Cydulka RK, Meckler GD, T. eds. Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e. New York, NY: McGraw-Hill; 2011.
  • American College of Rheumatology. Spondyloarthropathies. Accessed 11/4/2014.
  • Spondylitis Association of America. Enteropathic arthritis. Accessed 11/4/2014.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 11/4/2014...#13291