Skip to Main Content

Condition/Disorder Synonyms

  • Bekhterev's disease

  • Bekhterev's syndrome

  • Marie-Strümpell disease

  • Rheumatoid spondylitis

  • Spondylitis

  • Spondyloarthropathy

ICD-9-CM Code

  • 720.0 Ankylosing spondylitis (AS)

ICD-10-CM Code

  • M45.9 Ankylosing spondylitis (AS) of unspecified sites in spine

Preferred Practice Patterns

Key Features


  • Progressive inflammation of the spinal joints that leads to bone formation, natural fusion, and often increased kyphosis of the thoracic spine

  • Ankylosing means fusion; spondylitis means inflammation of the spine

Essentials of Diagnosis

  • Characterized by SI joint pain and dysfunction2

  • Etiology unknown

  • Pain for > 3 months

  • Relief with NSAIDs

  • Morning stiffness

  • Inflammation of the entheses3

    • - Healing and repair following inflammation of the enthuses leads to scarring that leads to extra bone formation3

General Considerations

  • Begins with intermittent low-back pain

  • Pain and stiffness at rest or sleep

  • Improvement with low levels of activity

  • May have rapid and severe onset

  • Does not follow the same course even in family members3

  • Secondary problems include

    • - Pulmonary fibrosis

    • - Restrictive lung disease

    • - Aortic heart valve (aortic insufficiency)

    • - Heart rhythm problems


  • Disease onset between ages 20 and 40 years

  • Male-to-female ratio 10:1

  • Caucasians afflicted more frequently than African-Americans

Clinical Findings

Signs and Symptoms

  • Kyphosis

  • Fatigue

  • Decreased range of motion and joint play

  • Intermittent back pain

  • Eye inflammation, iritis3

  • Heel pain/Achilles tendon3

  • Hip pain and stiffness, about 1/3 of the people with AS3

  • Shoulder pain, about 1/3 of the people with AS3

  • Jaw pain, about 10% of the people with AS3

  • Joint pain and swelling in the shoulders, knees, and ankles

  • Chest pain, costochondritis

  • Slight fever

  • Weight loss

  • Morning stiffness

  • Acute painful flare-ups and chronic, persistent pain

  • Thoracic and Pulmonary involvement

  • Neurologic symptoms are rare3

Functional Implications

  • Limited mobility

  • Aerobic endurance limitation

  • May impede ability to perform ADLs/IADLs

  • May impede participation in sports and other social activities

Possible Contributing Causes

  • Family history of ankylosing spondylitis

  • GI infections

Differential Diagnosis

  • Spinal stenosis

  • Disc herniation

  • Crohn's disease

  • Forestier disease

  • Reiter's syndrome (Reactive arthritis)

  • Whipple's disease

  • Yersinia arthritis

  • Facet joint arthritis

  • Psoriatic arthritis

  • Rheumatoid arthritis

Means of Confirmation or Diagnosis


  • MRI helpful in diagnosis to visualize structure of ligament, compressed or inflamed nerve root, disc pathology

  • X-ray/plain-film radiograph helps ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.