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Ankylosing Spondylitis (AS)

(see also: Spondyloarthropathies)


  • affects young men (ages 15 to 25 years), but may also begin in middle-aged men;
    • disease is often more severe when it occurs early in life;
  • disease characterized by insidious onset of pain and stiffness in lower back associated w/ gradual loss of spinal mobility;
  • illness may cause inflammation in uveal tract (iritis in 25%) & in intima of aorta;
  • symptoms are typically worse in the morning and in the middle of the night;
  • note: that in women, the symptoms of ankylosing spondylitis often first present during pregnancy;
  • labs: HLA-B27 (may be present in up to 8% of unaffected white population);

Spine in Ankylosing Spondylitis »

  • disorder has a tendency to progress slowly, w/ diminished mobility of the spine and sacroiliac joints;
  • early diagnosis can often be made with a CT scan of the sacroiliac joints;
  • cervical spine in ankylosing spondylitis:
    • acute neck pain in pt w/ AS is usually caused by frx thru ankylosed spine;
    • frx involves all columns & may be assoc w/ dramatic change in neck alignment;

reference: Uncommon Complication After Revision Hip Surgery

Peripheral Arthritis

  • may involve hips, knees, ankles, toes, (rare upper extremities).
  • these may precede the back pain by several years;
  • arthritis is acutely painful but rarely chronic or destructive;

hip joint

  • is affected in up to 50 % of patients with AS, and when it occurs it is often bilateral;
  • protrusio and hip flexion contractures are common;
  • heterotopic ossification may follow THR;
  • total hip replacement:
    • hetertopic ossification of the hip;
      • occurs in 20-40 % of hip replacements and is more common w/ trochanteric osteotomy;
    • to avoid heterotopic ossification consider insertion of a cemented acetabular component followed by 750 rads around the component;

Childhood AS

  • AS may develop in children & resembles pauciarticular JRA;
  • usually boys over 8 years of age
  • asymmetric peripheral arthritis of lower extremities.
  • must be differentiated from DISH;