AS

Question 1

Briefly define the term ankylosing spondylitis.

Answer 1

An uncommon systemic inflammatory disorder characterised by:

a. pain and stiffness
b. stiffening and fusion of the spine and sacroiliac joints

Question 2

Discuss the pathology of ankylosing spondylitis.

Answer 2

Two basic lesions are seen:
a. Synovitis
• especially vertebral facet joints, sacroiliac joints and costovertebral joints
• synovitis results in the destruction of articular cartilage and periarticular bone

b. Inflammation at the fibro-osseous joints of syndesmoses, especially:
• I/V discs
• manubria sterni
• bony insertions of large tendons & ligaments
• sacroiliac ligaments
• symphysis pubi

Question 3

Discuss the 3 stages of pathology in AS.

Answer 3

Stage 1 (inflammation)

• Inflammation of fibrocartilage in cartilaginous joints, followed by changes in the fibrous tissue of the joint capsule, cartilage that surrounds the IV/discs, entheses (enthesitis) and periosteum.
o infiltration by inflammatory cells
o granulation tissue formation
o erosion of adjacent bone and fibrocartilage

Stage 2 (Repair):

• Replacement of granulation tissue by fibrous scar tissue (ie inflammation subsides; healing by fibrosis occurs).

Stage 3 (Ossification)

• Reactive new bone formation in:
o articular bone (results in sclerosis)
o adjacent ligaments
o other joint structures
• Ossification of the fibrous tissue of the joint cause ankylosis of the joint.

Question 4

Discuss the articular manifestations of ankylosing spondylitis.

Answer 4

• Pain
• Peripheral Arthritis
• Decr. ROM and deformity of spine

Question 5

Discuss the extra-articular manifestations of ankylosing spondylitis.

Answer 5

1. Extra articular manifestations
   a. anterior uveitis
   b. aortic valvular incompetence (1-2% of longstanding cases)
   c inflammatory bowel disease especially Crohn’s disease and ulcerative colitis.
2. Respiratory problems (fibrosis following inflammation)
3. Fever, fatigue, anorexia, weight loss, anaemia.
4. Neurological symptoms and signs from:
   a. compression radiculitis
   b. vertebral fracture
   c. vertebral subluxation
   d. cauda equina syndrome

Question 6

Briefly describe the radiological manifestations of ankylosing spondylitis.

Answer 6

1. Cardinal sign: erosion and fuzziness of SI joints and periarticular sclerosis (eventually bony ankylosis occurs).
2. Vertebral changes: flattening of vertebral body concavity (squaring).
3. Ossification across the I/V discs creates “syndesmophytes” which span the IVD gaps of vertebrae.
4. Bridging at several levels results in a “bamboo spine” appearance.
5. Spotty ligamentous ossification.

Question 7

List three laboratory investigations that could be used in the diagnosis of ankylosing spondylitis.

Answer 7

1. ESR is usually elevated in active phases.
2. HLA-B27 is positive in 90% of patients.
3. RF tests negative.