AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Spondyloarthritis or spondyloarthropathy refers to a group of chronic inflammatory conditions affecting the joints, tendon and ligament attachments, and sometimes nonskeletal structures. Ankylosing spondylitis (AS) is one of these inflammatory diseases. It primarily affects the axial joints, including the spine and sacroiliac joints. It causes eventual fusion of the spine. Peripheral joints may be involved.

Pathophysiology

Inflammation at the sites of insertion of ligaments and tendons in the bones is the primary pathological process. Reactive bone growth occurs that is cumulative with each new attack. The disorder is predominantly skeletal, with ankylosis of the spine; involvement of hips, knees, and occasionally small joints; and plantar fasciitis.

Nonskeletal problems associated with AS may include iritis, uveitis, aortitis, pulmonary fibrosis, amyloidosis, and inflammatory bowel disease. Neurological complications include C1-C2 subluxation, tendency to spinal fractures with minor trauma, spinal stenosis in the cervical or lumbar regions, chronic inflammatory cauda equina syndrome, and radiculopathy secondary to fracture or compression.

Frequency

United States

In the general population, 1.4% are affected.

Sex

Male-to-female ratio is approximately 3:1.

Age

Peak onset is in adolescents and adults aged 15-30 years. A juvenile form also exists.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Patients typically present in their late teens or twenties. Large joints of the lower extremities are involved more commonly in the juvenile form than in the adult form.

• Patients usually describe a gradual onset of low back pain over 3 or more months. The pain is described as follows:
• • Worse in the morning with improvement during the day
  • Better with activity and worse with rest (helps in distinguishing AS from mechanical low back pain)
  • Gradual ascending pattern from the lumbar region to the thoracic and then the cervical spine
• Approximately 25% of patients present with complaints of proximal joint involvement. Rarely, small joint involvement is a presenting feature.
• Patients may describe pain and stiffness of the rib cage, which may or may not be pleuritic in nature. Atypical chest pain may be present.
• Presentation may be atypical or as a forme fruste.

Physical

• Examine for tenderness over the sacroiliac joints. Look for loss of lumbar lordosis and limited range of lumbar motion. In early phases of the disease, range of motion limitations may be due to muscle spasm. However, later it is due to bony fusion.
• Measure for limitations in chest expansion.
• Range of motion of the entire spine may be limited. In chronic, untreated cases, thoracic kyphosis is increased. This results in a characteristic posture in which the patient cannot look to the horizon.
• Acutely involved joints may have overlying purplish discoloration.

Causes

• About 90-95% of patients have the HLA-B27 antigen.
• Onset and flare-ups may be due to poorly understood environmental factors.
• Presumably, a fairly benign bacterium or virus can be antigenically similar to human ligaments.
• In a susceptible individual, a mild infection might stimulate an abnormal immune response.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Amyloidosis
Cervical disk syndromes
Mechanical back pain
Rheumatoid arthritis
Lumbosacral disk syndromes
Lumbosacral spondylosis
Spinal injury
Back pain

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Low-grade anemia of chronic disease may be present.
• Antinuclear antibody (ANA) and rheumatoid factor (RF) are within reference ranges.
• Erythrocyte sedimentation rate (ESR) is normal or mildly elevated; it is more likely to be elevated with active inflammation.
• C-reactive protein may be elevated with increased disease activity but is not a better indicator of inflammation than ESR.
• Serum alkaline phosphatase may be elevated when active bone remodeling is occurring.
• HLA-B27 antigen is positive 90-95% of the time but, notably, is not always present. Furthermore, its presence is not sufficient to make the diagnosis. The test is most helpful when diagnosis is not clear.
• Cerebrospinal fluid (CSF) protein may be elevated mildly during acute exacerbations.

Imaging Studies

• Plain radiography of the pelvis shows sacroiliitis or fusion of sacroiliac joints.
• Lumbar spine radiography may show ossification of the anterior longitudinal ligament and fusion of facet joints. The appearance gives rise to the term bamboo spine. With extensive fusion of the spine, a patient may have a poker spine.
• CT scan will show bony fusions and eroded laminae and spinous processes.
• MRI may be needed to document atlantoaxial subluxation. MRI may be indicated after trauma to evaluate the spinal cord and to rule out cauda equina syndrome or epidural hematoma.
• • Cauda equina syndrome may be inflammatory or compressive.
  • In inflammatory cauda equina syndrome, the spinal canal is normal to large with CSF diverticula that are best seen on MRI.
• Plain films or CT scan of the spine may be indicated after trauma to evaluate for bony injury.

Other Tests

• Occasionally, joint aspiration may be needed to rule out septic arthritis. With ankylosing spondylitis, synovial fluid may reveal a neutrophilic leukocytosis.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

General principles of management include the following:

• Exercise and postural training
• Medications to decrease pain and inflammation, tumor necrosis factor-alpha antagonists are valuable recent additions to the medication options. When used, they rapidly reduce symptoms and slow disease progression.
• Diagnosis and treatment of potential complications

Surgical Care

Surgical treatment may be necessary for some complications of ankylosing spondylitis.

• Surgical fusion may be required for stabilizing atlantoaxial subluxation.
• Cervical spine fractures require rigid immobilization, usually with a halo. In the past, surgical fusion was usually not performed. With neurological deficit, early surgical intervention with fusion is often recommended. Neurological deficit often improves after surgery.
• Surgery rarely is indicated for correction of uncomplicated thoracic kyphosis. If functional impairments are present, correction of the spinal deformity may be necessary; however, postoperative mortality from various complications is substantial, 4%.
• Thoracolumbar fractures require reduction of displacement and stabilization, usually with rods. Laminectomy rarely is needed.
• Decompression of cervical or lumbar spinal stenosis is indicated when neurological structures are involved.
• If weight-bearing joints are involved, hip or knee replacement may be necessary. The most common surgical procedure in these patients is a total hip arthroplasty.

Consultations

• If patients have complaints of eye pain, visual changes, or increased lacrimation, an ophthalmologist should be consulted to evaluate and treat for iritis or uveitis and rule out other causes of these conditions.
• Chest pain may require evaluation by a cardiologist or pulmonologist. Aortic regurgitation, sometimes associated with heart block, may need further treatment. Because apical pulmonary fibrosis may allow for opportunistic infection, pulmonary care may be necessary.
• Consultation with an orthopedist or neurosurgeon is indicated when spinal trauma occurs or in the setting of persistent pain or neurological deficit.
• Orthopedic care may be needed if weightbearing or shoulder joints are involved. Plantar fasciitis may require orthopedic or podiatry consultation.
• If associated inflammatory bowel disease is present, evaluation and treatment by a gastroenterologist may be necessary.

Activity

• Daily bending, twisting, and gentle range of motion exercises help prevent postural deformities and restriction of joint range of motion.
• Breathing exercises are recommended to prevent chest wall immobility.
• Encourage good sleeping posture with a small pillow on a firm mattress in either the supine or prone position.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The goal of pharmacotherapy is to control pain and decrease inflammation. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used medications. Sulfasalazine has been shown to be effective for peripheral joint involvement. Steroids and immunosuppressive agents are used sometimes. Injections of local steroids may offer symptomatic relief for local inflammation.

Drug Category: Nonsteroidal anti-inflammatory drugs

These agents reduce pain and inflammation. No particular NSAID has been shown to be clearly superior for treating ankylosing spondylitis.

Drug Category: Tumor necrosis factor antagonists

These agents inhibit the activity of cytokine TNF-alpha. Indications are a definitive diagnosis, active and refractory disease, with failure of conservative treatment. Treatment should be discontinued for patients who do not respond within after 6-12 weeks. Before use, refer to current practice guidelines for more complete discussions.

Drug Category: Antirheumatic agents

This agent relieves pain and joint swelling and treats GI lesions associated with inflammatory bowel disease.

Drug Category: Corticosteroids

These agents relieve inflammation and joint pain associated with ankylosing spondylitis.

Drug Category: Antimetabolites

These agents are second-line therapy to control symptoms of joint pain and inflammation in ankylosing spondylitis.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Complications

• Atlantoaxial subluxation may occur spontaneously and can be associated with a severe myelopathy. It is found in about 20% of patients who have a mean disease duration of 10 years. Clinically significant myelopathy requiring fusion is found in only 2%.
• Cervical spinal fractures are uncommon and usually are seen in patients with advanced disease.
• • Fracture usually results from minor trauma. Typically, the fracture is through the intervertebral space at level C5-C6 or C6-C7. Neurological deficits associated with spinal fracture may be delayed for 2-30 days.
  • Approximately 57% have severe neurological sequelae. Overall mortality rate is 35%, about twice that of a similar fracture in healthy individuals.
• Cervical myelopathy may result from cervical spinal stenosis.
• Thoracic and lumbar spinal fractures are less common than cervical spinal fractures. They usually result from minor trauma and may be multiple. Severe neurological deficits are frequent.
• Lumbar spinal stenosis may result in a cauda equina syndrome.
• • Chronic inflammatory cauda equina syndrome occurs only in long-standing AS and may occur when other aspects of the disease are seemingly inactive.
  • Patient described a gradual onset of buttock and leg pain. Sensory symptoms are often mild and symmetrical, often not noticed by the patient.
  • Motor involvement and bowel or bladder dysfunction are variable.
  • This condition is slowly progressive to stable for years to decades.
  • Neither surgery nor steroid therapy is beneficial.
• Radiculopathies may occur as a result of foraminal stenosis, disc disease, or fracture at the level of a nerve root.

Prognosis

• Symptoms of pain and stiffness are common and may be moderately severe to severe. Patients have few problems with social interactions, although depression is common.
• Most patients remain employed and relatively few develop severe functional disability. Disability correlates with duration of disease, disease activity, and spinal mobility. Peripheral joint involvement also results in greater impairment.
• The medical cost of treating AS can be relatively low compared with the costs of other rheumatologic diseases. The use of tumor necrosis factor antagonist agents is very expensive.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Angular kyphosis may result from a spinal fracture. Evaluation often requires imaging techniques, since neurological deficits may be delayed.
• Nocturnal pain in a weight-bearing joint is atypical and should be evaluated.
• Persistent neck or back pain after a seemingly minor trauma requires evaluation to rule out a fracture. Multiple fractures are a possibility, which may be difficult to see on a plain x-ray. Obtain CT or MRI scans and image the spine liberally to avoid missing an occult fracture.
• With preexisting kyphosis, a suspected thoracolumbar fracture may be a contraindication to immobilization in the supine position. Severe neurological deficit may result.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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• Trent G, Armstrong GW, O'Neil J. Thoracolumbar fractures in ankylosing spondylitis. High-risk injuries. Clin Orthop Relat Res. Feb 1988;227:61-6. [Medline].
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• Zochling J, van der Heijde D, Burgos-Vargas R, et al. ASAS/EULAR recommendations for the management of ankylosing spondylitis. Ann Rheum Dis. Apr 2006;65(4):442-52.
• van der Linden S, van der Heijde D. Ankylosing spondylitis. Clinical features. Rheum Dis Clin North Am. Nov 1998;24(4):663-76, vii. [Medline].

Article Last Updated: Jan 8, 2007