Ankylosing Spondylitis

Question 1

Define ankylosing spondylitis.

Answer 1

seronegative inflammatory arthropathy affecting preferentially the axial skeleton and large proximal joints

Question 2

What is the aetiology of ankylosing spondylitis?

Answer 2

• Unknown
• Strong linkage with HLA-B27 gene (>90% HLA-B27 positive, general population frequency ~8%)
• Infective triggers and antigen cross-reactivity with self-peptides have been suggested

Question 3

Where does inflammation start in ankylosing spondylitis? Where does it spread to and what happens?

Answer 3

• Inflammation starts at the entheses (site of attachment of ligaments to vertebral bodies)
• Persistent inflammation is followed by reactive new bone formation
• Changes start in lumbar and progress to thoracic and cervical regions
  
  • Squaring of vertebral bodies
  • Formation of syndesmophytes (vertical ossifications bridging the pargins of the adjacent vertebrae)
  • Fusion of syndesmophytes and facets joints (ankylosis and spinal immobility)
  • Calcification of anterior and lateral spinal ligaments

Question 4

How common is ankylosing spondylitis?

Answer 4

• Common
• Affects ~0.25-1% of UK population
• Earlier presentation in men
• Male:female ration 6:1at 16 years old and 2:1 at 30 years

Question 5

How does ankylosing spondylitis present?

Answer 5

• Low back and sacroiliac pain
• Disrupted sleep (worse in morning, improves on activity, returning with rest)
• Progressive loss of spinal movement
• Symptoms of asymmetrical peripheral arthritis
• Pleuritic chest pain (caused by costovertebral joint involvement).
• Heel pain (plantar fasciitis)
• Non-specific symtoms malaise and fatigue)

Question 6

What are the signs of ankylosing spondylitis on examination?

Answer 6

• Decreased range of spinal movements
• Decreased lateral spinal flexion and occiput-wall distance (with the patient standing
• Schober’s test - mark is made on the skin of the back in the middle of a line drawn between the posterior iliac spine. A mark 10cm above this is made. The patient is asked to bend forward and the distance between the two marks should increase by >5cm on forward flexion. This is reduced in ankylosing spondylitis.
• Tenderness over SI joints

_In later stages - t_horacic kyphosis and spinal fusion, question-mark posture

Signs of extra-articular disease:

• anterior uveitis (red eye),
• apical lung fibrosis,
• reduced chect expansion (fusion of costovertebral joints);
• aortic regurgitation (cardiac diastolic murmur)

Question 7

What investigations would you do for ankylosing spondylitis?

Answer 7

Bloods:

• FBC - anaemia of chronic disease
• Rheumatic factor - negative
• Raised ERS/CRP

Radiographs

• Anteroposterior and lateral radiographs of spine

Lung function tests:

• Assesses mechanical ventilatory impairment from kyphosis

Question 8

How do you manage ankylosing spondylitis?

Answer 8

• NSAIDs
• Sulfasalazine
• Corticosteroid intra-articular joint injections
• TNA-alpha inhibitors - adalimumab
• Physiotherapy