Ankylosing Spondylitis

Station 5: Ankylosing Spondylitis

You are asked to see a 23 year old man who has back pain.

HISTORY (3 mins)

  • SOCRATES and back pain RED FLAGS (bowel or bladder incontinence or retention, saddle anaesthesia, new leg weakness or sensory loss, any history of cancer or weight loss)
  • TIMING- since when, all the time/come and go, progression (is it getting worse), sudden/gradual onset, how often does it happen? When does it happen?
  • Ankylosing spondylitis specific questions
    • When is pain worst? Is it worst in the morning?
    • Does exercise help?
    • Stiff in morning? How long for?
    • Do you wake in the night with pain?
    • Pain in buttocks too?
    • Neck pain?
    • Plantar fasciitis, Achilles tendonitis, dactylitis (ever had a swollen finger/toe)
    • Any problems with other joints? Eg hips, knees
    • Skin eg. Psoriasis
    • Eye- ever had painful red eye?
    • Bowel- loose stools, weight loss ie. IBD
    • Urethral dc, sexual hx
    • CP, SOB, dry cough, palps, ankle swelling
  • PMH (psoriasis, IBD, heart murmur, lung fibrosis, kidney problems), Fx (psoriasis, IBD, joints/back problems), Dx (including treatments tried), Sx
  • IMPACT on life/work


EXAMINE (3 mins focussed examination with diagnosis in mind)

  • Gait
  • Inspect from front, side, behind. Observe stooped question mark posture (loss of lumbar lourdosis and fixed thoracic kyphosis with hyperextensions of cervical spine to maintain horizontal gaze). Observe for protuberant abdomen.
  • Palpate- spinous processes, muscles, sacroiliac joints
  • Range of movement neck
  • Range of movement back
  • Offer to perform Shobers test (dimples of venus, 5cm below, 10cm above, bend forward, positive if <5cm expansion)
  • Occiput-wall distance
  • Look for red eyes
  • Chest expansion, check for PPM, feel apex beat
  • Listen for AR murmer, listen for apical creps
  • Look at elbows- psoriasis
  • Hands- dactylitis, psoriatic plaques/nail changes,synovitis, feel pulse
  • Feet- tendonitis, dactylitis, psoriasis
  • Examine any joints that the patient has mentioned as problematic
  • Neuro- assess power, sensation, plantars.

ICE and EXPLANATION (2 mins)

A suggested explanation is as follows:

“There are many causes of back pain- such as muscle strains, disc problems, fractures. But from what you have told me it sounds like you may have a type of arthritis that mainly affects the back causing inflammation of the spine leading to pain and stiffness. It tends to occur in young men like yourself. I will arrange for you to have blood tests and Xrays of the spine and pelvis and refer you to see a rheumatologist as this is their area of expertise. In the mean time I will prescribe you an anti-inflammatory painkiller to reduce the inflammation. Physiotherapy and exercise are important to keep the spine mobile. Swimming is particularly good”


VIVA (2 mins)

Ankylosing spondylitis is a chronic inflammatory condition affecting the sacroiliac joints, the spine and sometimes the peripheral joints.  It can be associated with enthesitis, iritis, dactylitis, psoriasis and inflammatory bowel disease.


What are the complications/extraarticular manifestations of AS?

  1. Anterior uveitis 30%
  2. Aortitis 4% and aortic regurgitation
  3. Apical fibrosis is rare
  4. AVN block 10%
  5. Amyloidosis (secondary)
  6. Atlantoxial dislocation causing cord comp
  7. IgA nephropathy


Are you aware of any scoring systems?

BASDAI (Bath ankylosing spondylitis disease activity index)

BASFI (Bath Ankylosing Spondylitis Functional index)

BASMI (Bath ankylosing spondylitis metrology index)

BAS-G (Bath AS Patient Global Score)


What tests would you do?

  1. Inflamm markers- CRP, ESR (positive in 30%), also Hb, U+E (renal dysfunction due to NSAIDs, IgA nephropathy, amyloid)
  2. HLA B27 is positive in more than 90% with ankylosing spondylitis (8% of population carry the gene but only 1 in 15 get AS)
  3. Xray lumbar spine and SI joints and pelvis- can be normal in early disease
  4. MRI for early changes
  5. Urine dip for blood and protein
  6. ECG for conduction problems
  7. Echo- AR, Aortic root dilatation
  8. Sats, CXR, spirometry, HRCT to assess for fibrosis

What changes would you see on an Xray?

Bilateral symmetrical sacroiliac erosive changes with subchondral sclerosis, eventual obliteration and fusion of the SIJ.  Marginal syndesmophytes bridge multiple vertebrae causing a bamboo spine appearance.  Squaring of vertebral bodies can be seen on a lateral film.

Differential diagnosis of sacroilitis:

  • PsA
  • IBD arthritis
  • ReA


  1. Physiotherapy, occupational therapy, exercise
  2. Analgesia eg.paracetamol, NSAIDs+PPI
  3. Smoking cessation
  4. Bone protection
  5. Intraarticular/intralesional/im steroid for enthesitis/arthritis.
  6. Methotrexate for peripheral but not axial disease
  7. Anti-TNF agents for axial disease once failed 2 NSAIDs at max dose for 4 weeks and the BASDAI score is ≥4 on 2 occasions 3 months apart
  8. Surgery- joint replacements eg. hip, valve replacement
  9. Management of the complications/extraarticular features involves liaising with other specialties


Written by Dr Sarah Kennedy

Resources used to make this document include the references listed on the PACES webpage and also:

BSR and BHPR guideline for the treatment of axial spondyloarthritis (including ankylosing spondylitis) with biologics.

Rheumatology Secrets, by Sterling West