Ankylosing spondilytis

Question 1

Ankylosing spondylitis generalities

Answer 1

• Primarily affects the axial skeleton, and only secondarily the appendicular skeleton.
• Males between 15-35 years of age.
• Of all the inflammatory arthropathies is the least erosive and the **most ossifying.

Question 2

Ankylosing spondylitis common radiographic findings

Answer 2

• Normal mineralization before ankylosis, generalized osteoporosis after it.
• Subchondral bone formation present before ankylosis.
• Erosions are small and localized.
• Abscence of subluxations.
• Abscence of cysts.
• Ankylosis.
• Bilateral symmetrical.
• Sacroiliac joints and the spine, ascending from the lumbar to the cervical, then hips, shoulders, knees, hands and feet.

Question 3

Sacroiliac joints involvement of ankylosing spondylitis

Answer 3

• It is the first involvement of the disease.
• Bilateral and symmetrical.
• Small erosions seen first on the iliac side and then the sacral side (Perforated edge of a postage stamp).
• Erosions are surrounded by a small amount of bone repair (not extensive).
• The synovial aspect of the joint will ankylose relatively early.
• It is common to the entire SI joint to ankylose.
• Ossification of the ligaments in the posterosuperior portion of the SI joint is seen radiographically as a star.
• Enthesopathy of the iliac crest and ischial tuberosities.
• The pubic symphisis may be involved in 23% of patients.