MSS04 Introduction To Inflammatory Joint Disorders

Question 1

Rheumatology

Answer 1

Disorders of ***CT, esp. joints and related structures, characterised by Inflammation, Degeneration or Metabolic derangement

Include:

1. Rheumatoid Arthritis
2. Spondyloarthritis
3. Gout
4. Systemic Lupus Erythematosus
5. Scleroderma
6. Dermatomyositis
7. Vasculitis
8. Others

Question 2

Rheumatoid arthritis

Answer 2

1. Systemic ***autoimmune disease
2. Characterised by inflammatory polyarthritis (Bilateral)
3. Painful joints —> pain and stiffness often ***worsen following rest
4. Swelling
5. Impaired daily function

Question 3

***Pattern of joint involvement in RA

Answer 3

1. Proximal interphalangeal joint (PIP) (Thumb無呢個joint)
2. Metacarpophalangeal joint (MCP)
3. Carpometacarpal joint (CMC)

***NO Distal interphalangeal joint (DIP)!!!

Question 4

***Clinical features in RA

Answer 4

Synovial proliferation and inflammation

• ***↑ Synovial thickness
• Swan neck deformity (DIP flexion with PIP hyperextension)
• Bouteonniere deformity (PIP flexion with DIP hyperextension)
• Mallet finger (inability to extend the finger tip)

Others ***extra-articular features:

• lung fibrosis
• haematological involvement (Felty’s syndrome)
• ocular involvement (episcleritis, scleritis)
• vasculitis
• rheumatoid nodule
• amyloidosis

Question 5

Treatment principle of RA

Answer 5

1. ***Suppress inflammation
2. Prevent joint damage
3. Prevent complications

Question 6

Treatment of RA

Answer 6

1. Drug treatment
   - ***Symptom-modifying anti-rheumatic drugs
   —> NSAIDs
   —> COX-II inhibitor

• ***Disease-modifying anti-rheumatic drugs (DMARDs)
  —> conventional (Methotrexate, Sulfasalazine, Azathioprine, Chloroquine, Cyclophosphamide, Cyclosporin, Mycophenolate)
  —> biological (Etanercept, Anakinra, Abatacept, Rituximab)
  —> target synthetic (JAK inhibitor: Tofacitinib)

2. Physiotherapy
3. Occupational therapy (splinting, daily function)
4. Patient support
5. Surgery

Question 7

Gout

Answer 7

• Inflammatory arthritis
• ***Urate acid crystal deposits in the joints (renal problem —> cannot excrete uric acid properly)
• Rapid onset
• usually affect ***MTP joint (雞眼)
• Could have systemic symptoms e.g. fever
• Mimic other conditions e.g. septic arthritis
• Investigation: ***Serum uric acid level
• Definitive diagnosis: ***Arthrocentesis: urate crystals in joint

Stages:

• Stage I: asymptomatic ***hyperuricaemia
• Stage II: acute intermittent arthritis
• Stage III: chronic arthritis with acute exacerbation

Treatment:

• Acute phase: stop gouty attack
• Chronic phase: prevent attack and joint damage (by ↓ serum uric acid level)

Question 8

Spondyloarthritis (Bamboo spine)

Answer 8

• Inflammation of spine and peripheral joint
• **Spinal bone formation and **Ankylosis (stiffening and immobility due to fusion of bones)
  —> Ankylosing Spondylitis
• Pain and functional impairment: too rigid cannot bend
• Final stage of AS: severe ***kyphosis of thoracic and cervical spine

Genetic predisposition:
- Peptide-binding groove of ***HLA-B27: disease predisposing

Radiography:

• X-ray: ***Bamboo spine (thin, curved, radiopaque spicules that completely bridge adjoining vertebral bodies)
• MRI: ***Hyper-intense area —> inflammation

Other signs and symptoms:

• Peripheral spondyloarthritis: usually affect big joint: swollen, red
• Psoriasis (scaly patches and plaques)
• Dactylitis (joint + tendon inflammation, whole digit swollen)
• Enthesitis (inflammation of entheses, site where tendons and ligaments insert into bone e.g. Achilles tendon at Calcaneus)
• Anterior uveitis
• Aortic regurgitation
• Apical lung fibrosis

Diagnosis:

• Non-radiographic: ***HLA-B27, MRI Sacroiliac joints
• Radiographic: X-ray ***Sacroiliac joint (sacroiliitis)

Treatment:

• NSAID
• Axial joint: biological DMARD
• Peripheral arthritis: conventional DMARD
• Physiotherapy
• Surgery

Question 9

Osteoarthritis

Answer 9

• commonest cause of ***non-inflammatory arthropathy
• predominantly affects elderly
• prevalence increases steeply with age —> affects 75% of women >= 65
• ***Weight bearing joints affected
• no effective treatment
• symptomatic relief
• replacement surgery

Imaging features:

• Preserved bone density
• ***Joint space narrowing (cartilage destruction / fibrillated cartilage)
• ***Subchondral sclerosis
• ***Subchondral cysts
• ***Marginal osteophytes (Synovial hypertrophy)
• Joint deformity

Question 10

Other causes of joint pain

Answer 10

1. Systemic Lupus Erythematosus
2. Infections (hepatitis, parvovirus)
3. Septic arthritis (medical emergency)
4. Fibromyalgia (chronic widespread pain and a heightened pain response to pressure)

Question 11

***Investigations of arthritis

Answer 11

1. Physical examination:
   - Polyarthritis / Oligoarthritis / Monoarthritis
   - Symmetrical / Asymmetrical
2. Plain radiographs (Kellgren Lawrence classification)
   - narrowing of joint space
   - osteophyte
   - subchondral sclerosis
   - subchondral cyst
   - body contour change / defect
3. MRI
   - Meniscal tear (cannot be seen on X-ray)
   —> traumatic
   —> degenerative
   - Loose bodies
   - Cysts
   —> Baker’s cyst / Popliteal cyst
4. Blood tests
   - normal white cell count
   - normal ESR (↑ ESR / CRP —> inflammatory rather than degenerative causes)
   - normal bone profiles (Ca, PO4, alkaline phosphatase)
5. Joint aspiration
   - clear straw colour
   - total cell count <1000 / mm3
   - gram smear -ve, culture -ve
   - crystals -ve —> urate crystal (Gouty arthritis)

Question 12

***Summary of all joint disorder

Answer 12

Inflammatory

1. Rheumatoid arthritis
2. Gout
3. Spondyloarthritis
4. Systemic Lupus Erythematosus
5. Fibromyalgia (chronic widespread pain and a heightened pain response to pressure)

Non-inflammatory
1. Osteoarthritis

Infection:

1. Infections (hepatitis, parvovirus)
2. Septic arthritis (medical emergency)

Question 13

***OA vs RA

Answer 13

OA:

• Weight bearing joints affected
• ***Triphasic pain
• ***Stiffness
• ***Crepitus
• ***Bony enlargement
• Deformity
• Limping
• **4 signs:
• Narrowing of joint space / Articular damage
• Osteophyte
• Subchondral sclerosis
• Subchondral cyst

RA:
- Inflammatory polyarthritis (Bilateral)
—> ***Multiple joints
—> Bilateral
—> No DIP joint
—> ***pain and stiffness often worsen following rest
—> Swelling
- ***Synovial inflammation
- ***Synovial proliferation
- ***Extra-articular features: Systemic autoimmune disease (lung fibrosis, vasculitis, amyloidosis)