Spondyloarthropathies Flashcards
What is spondyloarthritis?
Seronegative Spondyloarthropathies -
Group of overlapping conditions that all share certain clinical features in their joint disease of the vertebral column.
Give 5 conditions that fall under the umbrella term spondyloarthritis.
- Ankylosing spondylitis.
- Reactive arthritis.
- Psoriatic arthritis.
- Enteropathic / Enteric arthritis.
- Juvenile idiopathic arthritis (JIA).
What clinical features do all spondyloarthropathies have in common?
- Axial inflammation - spine and sacroiliac joints
- Asymmetrical peripheral arthritis
- Absence of rheumatoid factor hence ‘seronegative’
- STRONG ASSOCIATION with HLA-B27 - but aetiological relevance is unclear
With what tissue type are all spondyloarthritis conditions associated?
They are all associated with tissue type HLAB27.
What is HLAB27? What is it encoded by?
Human Leucocyte Antigen (HLA) B27
- Class I surface antigen - present on all cells, except RBCs
- Encoded by Major Histocompatibility Complex (MHC) on chromosome 6
What is the function of HLAB27?
It is an antigen presenting cell.
Epidemiology: where is HLAB27 most commonly found?
Most common in the northern hemisphere - 9% in UK, very rare in subSaharan Africa
With which seronegative spondyloarthropathy is HLAB27 particularly associated with?
Prevalence of HLA-B27 affects prevalence of ankylosing spondylitis (AS).
Name 3 theories that can explain why HLAB27 is associated with spondyloarthritis.
- Molecular mimicry.
- Mis-folding theory.
- HLAB27 heavy chain hypothesis.
Describe the ‘molecular mimicry’ theory for explaining why HLAB27 is associated with spondyloarthritis.
Infectious agents have peptides very similar to HLAB27. An auto-immune response is triggered against HLAB27.
What joints tend to be affected in seronegative spondyloarthropathies?
Asymmetrical large joints.
What signs would make you think of spondyloarthropathy diagnosis?
HINT: Mnemonic!
Think seronegative spondyloarthropathies (SpA) if SPINEACHE:
- Sausage digit (dactylitis)
- Psoriasis
- Inflammatory back pain
- NSAID good response
- Enthesitis (particularly in heel - plantar fasciitis)
- Arthritis
- Crohn’s/Colitis/elevated CRP (can be normal in AS)
- HLA-B27
- Eye (uveitis)
Define Ankylosing spondylitis.
Chronic inflammatory disorder of the spine, ribs and sacroiliac joints, with unknown aetiology.
Describe the epidemiology of AS.
1, Males > Females (more common + more severe)
2. Young adults (<30 YO)
3. 88% are HLA-B27 positive
4. Women present later and are under-diagnosed
5. Low incidence in African and Japanese people
6. Native North Americans have high incidence
What antibody is NEVER seen with ankylosing spondylitis?
Rheumatoid factor
Give 2 risk factors for AS.
- HLA-B27
- Environment:
* Klebsiella
* Salmonella
* Shigella
Does ankylosing spondylitis more commonly affect men or women?
Men
Describe the pathophysiology of AS.
- Inflammation in the anterior corners of the spine
- Local erosion of the bone at the attachments of the intervertebral + other ligaments (I.E. enthesitis)
- Fat is laid down
- Fat is replaced with bone - healed with new bone formation = Syndesmophytes
- Irreversible fusion of spine = stiffness!!
What joints does ankylosing spondylitis affect?
- Sacroiliac joints
- Joints of the vertebral column of the spine
- 1-3 joints
- Asymmetrical
Give 5 symptoms of ankylosing spondylitis.
- Lower BACK PAIN!
- Sacroiliac pain in the buttock region.
- Morning stiffness (takes at least 30 mins to improve)
- Stiffness worsens with rest + improves with movement.
- Waking in the second half of the night.
- Insidious onset - Slow onset -> 3 months.
- Usually <40 YO at onset.
- Enthesitis - Achilles tendinitis, plantar fasciitis (under heel) and tenderness around the pelvis and chest wall
Describe the back pain experienced in ankylosing spondylitis.
Radiating from sacroiliac joints to hips/buttocks.
Worse at night, improves towards end of day.
What is the time course of ankylosing spondylitis?
At least 3 months
With flares/remitting
Describe the severe clinical features of ankylosing spondylitis.
Severe disease - kyphosis and neck hyperextension - question mark posture - Bamboo spine
Give 2 characteristic spinal abnormalities in ankylosing spondylitis.
2 characteristic spinal abnormalities:
- Loss of lumbar lordosis + Increased kyphosis
- Lordosis = Normal inward curve of spine)
- Kyphosis = curvature of spine that causes top of back to appear more rounded than normal - Limitation of lumbar spine mobility in both sagittal and frontal planes
→ Reduced spinal flexion is demonstrated by the SCHOBER TEST.
→ A mark is made at the 5th lumbar spinous process and 10cm above, with the patient in the erect position.
→ On bending forward, the distance should increase to more than 15cm in normal individuals.
What is the Schober’s test?
Explain how to do Schober’s test.
This is a test used as part of a general examination of the spine to assess how much mobility there is in the spine.
Have the patient stand
Locate L5 vertebrae
Mark a point 10 cm above and 5 cm below
Ask pt to bend over as far as they can
Measure the new distance
Less than 20 cm is positive for AS
What is the typical clinical presentation of ankylosing spondylitis?
Typical patient is a man < 30 yrs with gradual onset of low back pain, worse at night, with spinal morning stiffness that is relieved by exercise.
Give 3 non-articular features of AS.
Non-articular features:
1. Anterior uveitis - inflammation of middle layer of eye
2. Associated with osteoporosis
3. Rarely; aortic incompetence, cardiac conduction defects and apical lung fibrosis, amyloidosis and IgA nephropathy