Ankylosing Spondylitis, Orthopedic Perspective

Ankylosing spondylitis (AS) is a chronic inflammatory disorder of the spine and the connection of the spine to the pelvis (sacroiliac joints). Sacroiliac joint involvement is considered the hallmark of this disorder and is a requirement for diagnosis.

Ankylosing spondylitis is categorized as a seronegative spondyloarthropathy. The term seronegative means that a blood test result does not show the presence of rheumatoid arthritis, and the term spondyloarthropathy means a disease that affects the joints of the spine. These inflammatory disorders affect multiple systems of the body. Other disorders in this category include Reiter syndrome (reactive arthritis); arthritis associated with inflammatory bowel disease, such as Crohn disease and ulcerative colitis; psoriatic arthritis; undifferentiated spondyloarthropathies; juvenile chronic arthritis; and juvenile-onset ankylosing spondylitis.

Ankylosing spondylitis affects approximately 0.1-0.2% of the world population and is more prevalent in individuals of Northern European ancestry. People with ankylosing spondylitis often have a family member with the disease or one of the other spondyloarthropathy disorders listed above.

The exact cause of ankylosing spondylitis remains unknown. A possible genetic link exists, as the risk of developing ankylosing spondylitis or any other seronegative spondyloarthropathy increases when a family member has the condition. 
 
Ankylosing spondylitis and the other spondyloarthropathies have also been linked to a specific protein, HLA-B27, in a person’s blood. If this protein is present, the risk of developing ankylosing spondylitis is multiplied 10 times. The specific role this protein plays in the development of ankylosing spondylitis is unclear.

Generally, the initial symptoms of ankylosing spondylitis occur in the sacroiliac joints as low back pain, hip pain and stiffness, or both, followed by pain and stiffness in the back and rib cage. Symptoms most commonly begin in late adolescence, and males are 3 times more likely to develop ankylosing spondylitis than females. The onset of symptoms in people older than 45 years is uncommon. If symptoms begin in those younger than 16 years, the disease is termed juvenile-onset ankylosing spondylitis, which is more common in Native Americans and in people who live in developing countries.

People with ankylosing spondylitis generally complain of back pain of gradual onset that may not become apparent until the condition is well established. The pain progresses with a series of flare-ups and remissions. The back pain is dull and poorly localized to the hips and buttocks. The pain often begins as unilateral (1 sided) and intermittent, but as the disease progresses, it becomes more persistent and bilateral (2 sided). 

Key components of a person’s medical history that suggest ankylosing spondylitis include the following:

• Gradual onset of low back pain



• Onset of symptoms prior to age 40 years



• Presence of symptoms for more than 3 months



• Symptoms worse in the morning or with inactivity



• Improvement of symptoms (especially morning stiffness) with exercise

Involvement of the hips and shoulder joints is possible but is more common in juvenile-onset ankylosing spondylitis. 
 
Involvement of the temporomandibular joint (TMJ) can lead to decreased range of motion in the jaw and occurs in approximately 10% of people with ankylosing spondylitis. 
 
Involvement of the ribs can lead to decreased range of motion of the chest wall and difficulty expanding the lungs during breathing. 
   
Long-term involvement of the spine eventually leads to a progressive decrease in range of motion ending with fusion of the vertebral bodies (that is, the bones of the spine grow together and prevent motion). Involvement of the cervical (neck) and upper thoracic spine can lead to fusion of the neck in a forward flexed position (see Multimedia Files 1-2). The fusion of the neck in this position can significantly limit a person’s ability to walk because of an inability to look straight ahead or to drive a car without adaptive mirrors because of difficulty turning the head. 
 
Other symptoms include the following:

• Acute iritis (inflammation of the iris, the colored part of the eye [more accurate]): Acute iritis occurs in 25-30% of people with ankylosing spondylitis and generally only affects one eye. Symptoms include pain, lacrimation (increased tearing), photophobia (sensitivity to light), and blurred vision.

• Aortitis (inflammation of the aorta, the major blood vessel) and aortic fibrosis (stiffening of the blood vessels): Involvement of the heart is generally a late finding in ankylosing spondylitis. Severe cases can lead to complete heart block or aortic valve insufficiency (weakening of the aortic valve).

• Pulmonary fibrosis (stiffening of the lungs): Pulmonary involvement is caused by involvement of the rib joints, which limits range of motion of the chest wall. Pulmonary fibrosis generally produces no symptoms. If a chest x-ray film is obtained for another reason, pulmonary fibrosis is a finding that may also show up on the film.

• Neurologic deficit (decreased function of the brain, spinal cord, muscles, and nerves): Neurologic deficits are caused by spinal fracture or cauda equina syndrome due to spinal stenosis (narrowing of the spinal canal). Spinal fracture is most common in the cervical spine (neck).

People should seek medical care if they feel they have the symptoms of ankylosing spondylitis. Those with progressive pain and stiffness in the hips and spine that is relieved with exercise may have ankylosing spondylitis.

A doctor can determine if a person’s symptoms are related to ankylosing spondylitis or another seronegative spondyloarthropathy disorder. Many of these symptoms are not specific to ankylosing spondylitis and can result from other causes or can be part of the normal aging process. A doctor can help determine the cause of the symptoms.

A doctor begins with a complete medical history and physical exam. The medical history of the person and his or her family members provides possible clues to help determine a diagnosis of ankylosing spondylitis. A strong family relationship for these disorders exists. Also, symptoms are typically worse in the morning and progressively improve throughout the day and with exercise. 

• The physical exam measures range of motion in the hips and spine. Specific areas of pain or tenderness are examined. A thorough exam should identify any of the associated disorders, including involvement of the eyes, heart, and lungs.



• Blood tests have a limited role in helping to diagnose ankylosing spondylitis. A blood test can determine if a person has the protein HLA-B27. A person with this protein has an increased risk of developing ankylosing spondylitis. However, this blood test is not necessary to help diagnose or treat the condition and is not commonly ordered by a doctor. Other blood tests may be ordered by a doctor to help rule out other possible causes of the person’s symptoms.
   
• Imaging studies (x-ray films) of the pelvis and the spine are commonly obtained to look at the sacroiliac (SI) joints (see Multimedia File 3). Involvement of the sacroiliac joints is a requirement for proper diagnosis of ankylosing spondylitis. X-ray film findings in the spine include squaring of the vertebral bodies and formation of bridging bone connecting the vertebrae (see Multimedia Files 4-7).



• X-ray films of other joints may show loss of the normal joint space or deformity (see Multimedia File 8).



• In people with neurologic findings, an MRI of the spine may be ordered to show the nerves and spinal cord (see Multimedia File 9).

The most important aspects of treatment include understanding the disease and incorporating a good exercise program at home. Ankylosing spondylitis is a progressive disease that leads to stiffness and pain in the joints. A good, regular stretching and exercise program can delay the progression of the disease.

Because of the potential for a rigid rib cage and lung involvement, people with ankylosing spondylitis who smoke should quit.

Currently, no definitive treatment of or cure for ankylosing spondylitis exists. 

• Nonsteroidal anti-inflammatory medications, such as ibuprofen (Advil or Motrin) or naproxen (Aleve or Naprosyn), are commonly used to decrease inflammation and pain.



• Aspirin has been shown to have limited benefit for people with ankylosing spondylitis.



• Oral corticosteroids, such as prednisone (Deltasone or Orasone), are not used for long-term treatment because of the high risk of side effects.



• Sulfasalazine (Azulfidine) and methotrexate (Rheumatrex) have been reported to be effective in some people with peripheral involvement of ankylosing spondylitis. Sulfasalazine is also useful in people with coexisting inflammatory bowel disease.



• The overproduction of the protein tumor necrosis factor (TNF) is thought to be the underlying cause of ankylosing spondylitis and other autoimmune disorders. Drugs that block TNF, such as infliximab (Remicade) and etanercept (Enbrel), are now approved to treat ankylosing spondylitis. These drugs target and may alter the disease process.

People with involvement of other systems should see the appropriate specialists (for example, for the eyes, an ophthalmologist; for the lungs, a pulmonologist; and for the heart, a cardiologist). Those with a painful red eye should see an ophthalmologist immediately.
 
Genetic counseling and support groups are useful in further educating people about the disease and in predicting those at increased risk.

For more information on support groups, see Web Links.

For more information on medications, see Understanding Ankylosing Spondylitis Medications.

In most cases, surgery is not indicated for people with ankylosing spondylitis. Surgical treatment is geared toward the resolution of complications related to the disorder. Surgical treatment of ankylosing spondylitis does not provide a curative benefit.

• People with significant involvement of the cervical (neck) or upper thoracic spine may have significant impairment in line of sight, eating, and psychological well-being. These people may benefit from extension osteotomy of the cervical spine (a realignment of the spine to allow the person to straighten the head and look forward). This procedure is difficult and hazardous, but if successful, it allows the person to return to a more functional life.



• People with autofusion of the spine due to the ankylosing spondylitis disease process who report a change in the position of the spine should be treated cautiously and should be considered to have sustained a spinal fracture. Surgical intervention may be necessary to reduce the risk of neurologic complications.



• People who develop bowel or bladder dysfunction should be evaluated immediately with an MRI to assess for possible cauda equina syndrome secondary to spinal stenosis (narrowing of the spinal canal). This is an emergency requiring surgery within 48 hours to prevent permanent loss of function.



• People with significant involvement of the hips or knees may need hip or knee replacement surgery as the disease progresses. Excess new bone formation may occur after surgery and gradually decrease joint function so that another surgery is required.

People with ankylosing spondylitis should have regular follow-up visits with their doctor to identify any new symptoms related to the disease and to determine if additional treatment is needed.

Currently, no method of preventing ankylosing spondylitis exists. However, a good stretching and exercise program can delay the normal disease progression.

Spondylitis Association of America
PO Box 5872
Sherman Oaks, CA 91413
(800) 777-8189
info@spondylitis.org

American College of Rheumatology
1800 Century Place, Suite 250
Atlanta, GA 30345-4300
(404) 633-3777

American Academy of Orthopaedic Surgeons
6300 North River Road
Rosemont, Illinois 60018-4262
(847) 823-7186

American Academy of Neurological and Orthopaedic Surgeons
10 Cascade Creek Lane
Las Vegas, NV 89113
(702) 388-7390
aanos@aanos.org

|Web Links|

Spondylitis Association of America, About Spondylitis

National Ankylosing Spondylitis Society (UK), Spondyloarthropathy Family

Arthritis Society, Ankylosing Spondylitis

Ankylosing Spondylitis International Federation

Arthritis Foundation, Ankylosing Spondylitis

KickAS.org

RISG.org, Reiter's Information & Support Group Inc.

Media file 1: Person with ankylosing spondylitis affecting the cervical (neck) and upper thoracic spine. The person's spine has been fused in a flexed position.

Media type:  Photo

Media file 2: Back view of a person with ankylosing spondylitis affecting the cervical (neck) and upper thoracic spine. The person's spine has been fused spontaneously in a flexed position.

Media type:  Photo

Media file 3: X-ray film of the sacroiliac joint of a person with ankylosing spondylitis.

Media type:  X-RAY

Media file 4: X-ray film of the spine of a person with ankylosing spondylitis. Ossification (bone formation) of the annulus fibrosis (outer ring of the intervertebral disk) has led to fusion of the spine with abnormal curvature.

Media type:  X-RAY

Media file 5: X-ray film of the spine of a person with ankylosing spondylitis. Ossification (bone formation) of the annulus fibrosis (outer ring of the intervertebral disk) and squaring of the vertebral bodies have occurred.

Media type:  X-RAY

Media file 6: X-ray film of the spine of a person with ankylosing spondylitis.

Media type:  X-RAY

Media file 7: X-ray films of a person with ankylosing spondylitis.

Media type:  X-RAY

Media file 8: X-ray films of a hand and an arm of a person with ankylosing spondylitis. Fusion of the joint spaces and deformity have occurred.

Media type:  X-RAY

Media file 9: MRI of the spine of a person with ankylosing spondylitis. Degenerative disk disease and bridging osteophytes (bone spurs) have occurred.

Media type:  MRI

Media file 10: X-ray film showing a vertebral fracture in a person with ankylosing spondylitis.

Media type:  X-RAY

ankylosing spondylitis, AS, sacroiliac joints, SI joints, seronegative spondyloarthropathy, HLA-B27, hip pain, juvenile-onset ankylosing spondylitis, TMJ, temporomandibular joint, acute iritis, aortitis, aortic fibrosis, pulmonary fibrosis, neurologic deficit, stiffness and pain in joints, sulfasalazine, methotrexate, infliximab, etanercept, extension osteotomy of the cervical spine, cauda equina syndrome, spinal stenosis, Reiter syndrome, arthritis, inflammatory bowel disease, psoriatic arthritis, undifferentiated spondyloarthropathies, juvenile chronic arthritis, back pain, tumor necrosis factor, TNF, hip replacement surgery, knee replacement surgery 

Author: S Craig Humphreys, MD, Orthopaedic Spine Surgeon, Department of Orthopedic Surgery, Center for Sports Medicine and Orthopedics.

Coauthor(s): Jason C Eck, DO, MS, Staff Physician, Department of Orthopaedic Surgery, Memorial Hospital; Scott D Hodges, DO, Consulting Surgeon, Department of Orthopedic Surgery, Center for Sports Medicine and Orthopedics.

Editors: Kristine M Lohr, MD, Associate Chief, Program Director, Professor, Department of Internal Medicine, Division of Rheumatology, University of Tennessee School of Medicine; Mary L Windle, Pharm D, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Pharmacy Editor, .com, Inc; Rick Kulkarni, MD, Assistant Professor of Medicine, David Geffen UCLA School of Medicine; Director of Informatics, Department of Emergency Medicine, UCLA/Olive View-UCLA Medical Center.