Inflammatory Arthritis

Question 1

What are the 3 main subgroups of inflammatory arthritis?

Answer 1

1) Rheumatoid arthritis (RA) –> a/w auto-ab (RF, anti-CCP)

2) Spondyloarthritis (SpA)  a/w HLA-B27
- P: Psoriatic arthritis (PsA)
- A: Ankylosing spondylitis (AS)
- I: IBD associated (enteropathic) arthritis
- R: Reactive arthritis (Reiter’s)
- S: Still’s disease (Juvenile Chronic arthritis)

3) Crystal arthritis: a/w intra-articular and soft tissue crystal deposition
- Gout
- Pseudogout (a.k.a. calcium pyrophosphate deposition disease; CPPD)

Other forms of inflammatory arthritis (I’ve added this section in myself)

• Septic Arthritis (including disseminated gonococcal)
• SLE

Question 2

What are the clinical features of inflammatory arthritis?

Answer 2

Symptoms: inflammatory pain

Signs: redness, swelling, loss of function – swelling and effusion is more severe than OA

Labs: raised CRP/ESR, NCNC anaemia (anemia of chronic disease)

Joint aspiration and synovial fluid analysis

• OA: usually <2000/uL
• Inflammatory: usually 2000/uL – 50000/uL
• Septic: usually >50,000/uL

Question 3

What does Axial Spondyloarthritis (spA) include?

What is ASAS classification for Axial Spondyloarthritis (spA)?

Answer 3

Includes

• Ankylosing Spondylitis (axSpA)
• Non-radiographic Axial SpA (nr-axSpA) – Sacro-Iliitis only on MRI; With time, will progress to AS

In patients with > 3 months back pain and age of onset <45 years

Sacroiliitis on imaging and >1 SpA feature

OR HLA B-27 positive and >2 other SpA features

Sacroiliitis on imaging

• active (acute) inflammation on MRI highly suggestive of sacroiliitis associated with SpA
• definite radiographic sacroiliitis according to modified New York criteria

SpA features

• inflammatory back pain
• arthritis
• enthesitis (heel)
• uveitis
• dactylitis
• psoriasis
• crohn’s/ colitis
• good response to NSAIDS
• family history of SpA
• HLA B27
• elevated CRP

Question 4

What does Peripheral Spondyloarthritis (spA) include?

What is ASAS classification for Peripheral Spondyloarthritis (spA)?

Answer 4

Includes

• Psoriatic Arthritis (PsA)
• Reactive Arthritis
• SpA related to IBD (Enteropathic)
• Undifferentiated SpA ie peripheral SpA that does not meet above Dx criteria, will eventually evolve into one of the above

Peripheral arthritis and/ or enthesitis and/ or dactylitis plus

> 1 SpA features:

• uveitis
• psoriasis
• crohn’s/ colitis
• preceding infection
• HLA- B27
• sacroiliitis on imaging

OR >2 other SpA features

• arthritis
• enthesitis
• dactylitis
• inflammatory back pain (ever)
• family history of spA

Question 5

What does SPINE ACHE (mnemonic of 11 features of SpA) stand for?

Answer 5

• S: sausage digit (dactylitis)
• P: Psoriasis (positive PMH) OR Positive FHx of SpA
• I: IBP - inflam back pain
• N: NSAIDs good response
• E: enthesis (plantar fasciitis, Achilles tendonitis)
• A: arthritis (axial or asym large jt)
• C: Crohn’s/ colitis ie IBD OR elevated CRP
• H: HLA-B27
• E: eye (uveitis) in all types of SpA

Question 6

What are the clinical features of inflammatory back pain?

Answer 6

• Age of onset <40 years
• Insidious (chronic, >3/12)
• Improvement with exercise
• No improvement with rest
• Pain at night (with improvement upon arising)

Question 7

What are the radiological tools to assess Sacroiliitis?

Answer 7

Anterior and Lateral Lumbar XR

X Ray Modified Ferguson view

• Helps to visualize the anterior and inferior most part of the SI joint.
• Which is most frequently affected in inflammatory arthritis

CT, MRI – for non-radiographical Sacro-Iliitis (to Dx nr-axSpA)

Question 8

What are the radiological findings of sacroiliitis?

Answer 8

• Width of the joint space: initially pseudo-widening –> eventual obliteration / ankylosis
• Bony Erosions
• Peri-articular Sclerosis (form of reactive sclerosis)
• Presence and types of bone bridging
• Distribution of changes (BL/ UL, Symmetrical/ Asymmetrical)

Question 9

What is the New York Classification of Sacroiliitis based on Xray findings?

Answer 9

• Grade 0: No changes / SI joint normal
• Grade 1: Suspected changes (blurry margins of SI joint gap)
• Grade 2: Minimal changes (minimal/ single erosion and small area of periarticular sclerosis)
• Grade 3: Advanced changes (distinct periarticular sclerosis, numerous erosions with widening of the articular gap
• Grade 4: Total ankylosis

Question 10

What are the red flags for back pain?

Answer 10

• Urinary / Bowel incontinence
• LL Weakness, Numbness, Paraesthesia
• Saddle Anaesthesia