Seronegative Arthritis Flashcards
What are some characteristics of seronegative arthritic conditions?
- Negative rheumatoid factor
- May be associated with HLA-B27
- Usually asymmetric
- More common in axial skeleton (spine) and larger joints
- Enthesitis
- Extra articular conditions: uveitis & IBD
What is enthesitis?
Inflammation of the area (entheses) at which a tendon or ligament inserts onto bone
What are some of the common seronegative arthritic conditions?
- Ankylosing spondylitis
- Psoriatic arthritis
- Bowel related arthritis (Crohn’s / UC)
- Reactive arthritis
What is ankylosing spondylitis? Who tends to get it?
- inflammatory rheumatic disorder that primarily affects axial skeleton and entheses
- Onset is in the 2nd/3rd decade of life, it is more common in males and about 80-95% percent of people with the condition have a mutation in HLA-B27
Is an HLA - B27 mutation diagnostic of ankylosing spondylitis?
No, the prevalence of HLA-B27 in Europe is around 10%, but the prevalence of ankylosing spondylitis is only about 1%
- About 80-95% of AS patients have the mutation though
How is HLA - B27 mutation implicated in the pathophysiology of ankylosing spondylitis? Which interleukin pathways are also heavily involved in the inflammatory cascade?
The inflammation thought to be due to improper self tolerance due to improper presentation of the HLA - B27 antigen, due to improper protein folding or improper presentation of other foreign antigens by the complex - triggers inflammatory cascade
IL-23 & IL-17 are heavily implicated and often the target of drug therapies
What clinical examination test is done to assess spinal mobility when ankylosing spondylitis is suspected?
Schober test
- Mark two lines 10cm apart on the patients back whilst upright (vertical orientation)
- Get the patient to lean forward and then measure the gap between the two lines
- If the gap increases to 15+ cm mobility is fine, if not can be a sign of ankylosing spondylitis
What are some other clinical examinations done to assess mobility / bone structure for ankylosing spondylitis?
- Lateral spinal flexion: measure how far patient can lean sideways without bending knees / lifting heels
- Tragus to wall: measure distance of ear tragus to wall with patient standing w back against wall (kyphosis?)
- Cervical rotation: how far can the patient rotate their head
What are the common signs / symptoms of ankylosing spondylitis?
- Inflammatory back pain (worse in morning, better with exercise) & sometimes shoulder pain
- Limitation of movement of spine in lateral and planes
- Limited chest expansion
- Bilateral sarcoilitis (pain in hips and buttocks)
- Systemic: anterior uveitis, apical lung fibrosis, aortic regurgitation
What are some changes that can occur in the bones of a patient with ankylosing spondylitis?
- Fusion of joints in the pelvic and spinal region
- Excessive calcification and ossification of bones / joints
- Syndesmophyte formation (calcifications / ossifications inside a spinal ligament or of the annulus fibrosus)
Investigations for suspected ankylosing spondylitis?
- MRI (picks up early sacroiliitis)
- Bloods: RF negative, anaemia, raised ESR
- X-Ray (only picks up later changes)
If scaroiliitis is unilateral what can that indicate?
- perhaps very early detection of ankylosing spondylitis
- can indicate inflammatory bowel disease related sacroiliitis
Management of ankylosing spondylitis?
- Physiotherapy (maintain flexibility)
- NSAIDs
- DMARDs (sulfasalazine)
- Anti-TNF / Anti-IL-17
- Surgery: hip / joint replacements or fracture repair
Which joints are most commonly affected by psoriatic arthritis?
- Large joints most common
- Small joints not uncommon
- Base of spine
What is psoriatic arthritis? Who tends to get it?
Inflammatory arthritis associated with psoriasis
- mean onset 40-50 yrs, 10% of psoriasis patients develop arthritis
- Also associated with HLA-B27
