Ankylosing spondylitis

Question 1

Define ankylosing spondylitis

Answer 1

Seronegative inflammatory arthropathy affecting preferentially the axial skeleton & large proximal joints

Question 2

Aetiology of ankylosing spondylitis

3

Answer 2

UNKNOWN
Strong association w/ HLA-B27 gene (90%)
Infective triggers & antigen cross reactivity w/ self peptides have been hypothesised

Question 3

Pathophysiology of ankylosing spondylitis

7

Answer 3

Inflammation starts at entheses
Persistent inflammation leads to new bone formation
Changes begin in lumbar vertebrae & progress superiorly
Vertebral bodies become more square
Syndesmophytes
Fusion of syndesmophytes & facet joints
Calcification of anterior & lateral spinal ligaments

Question 4

Define entheses

Answer 4

where ligaments attach to vertebral bodies

Question 5

Define syndesmophytes

Answer 5

vertical ossifications bridging margins between adjacent vertebrae

Question 6

Epidemiology of ankylosing spondylitis

prevalence, gender

Answer 6

COMMON

Earlier presentation in males

Question 7

Presenting symptoms of ankylosing spondylitis

10

Answer 7

Lower back & sacroiliac pain
Disturbed sleep
Pain pattern
- worse in the morning
- better w/ activity
- worse when resting
Progressive loss of spinal movement
Symptoms of asymmetrical peripheral arthritis
Pleuritic chest pain (due to costovertebral joint involvement)
Heel pain (due to plantar fasciitis)
Non specific symptoms (e.g. malaise, fatigue)

Question 8

Signs of ankylosing spondylitis on physical examination

4 + 3 later

Answer 8

Reduced range of spinal movement (particularly hip rotation)
Reduced lateral spinal flexion
Schober’s test
Tenderness over sacroiliac joints

Later stages
Thoracic kyphosis
Spinal fusion
Question mark posture

Question 9

Signs of ankylosing spondylitis on physical examination - extra articular disease
(5)

Answer 9

(5 As)
Anterior uveitis
Apical lung fibrosis
Achilles tendinitis
Amyloidosis
Aortic regurgitation

Question 10

Schober’s test

explain + result

Answer 10

2 fingers placed on patient’s back 10cm apart
Patient asked to bend over
Distance between fingers should increase by > 5cm on forward flexion
Reduced movement would suggest ankylosing spondylitis

Question 11

Investigations for ankylosing spondylitis

3 types

Answer 11

Bloods
Radiographs
Lung function tests

Question 12

Investigations for ankylosing spondylitis - bloods

3

Answer 12

FBC - anaemia of chronic disease
Rheumatoid factor - negative
ESR/CRP - high

Question 13

Investigations for ankylosing spondylitis - radiographs

3 + 3 late signs

Answer 13

Anteroposterior & lateral radiographs of spine
may show bamboo spine

Anteroposterior radiograph of sacroiliac joints
shows symmetrical blurring of joint margins

Later stages
Erosions
Sclerosis
Sacroiliac joint fusion

CXR - check for apical lung fibrosis

Question 14

Investigations for ankylosing spondylitis - lung function tests

Answer 14

Assess mechanical ventilatory impairment due to kyphosis