Gout

Epidemiology

  • Men > Women
  • More common in British Caucasians
  • Genetic link

Aetiology

  • Disease of abnormal purine metabolism
  • Results in deposition of monosodium urate crystals within synovial joints
  • Crystals are needle-shaped and cause florid synovitis

Inciting Factors

  • Alcohol
  • Purine-rich foods (e.g., oily fish)
  • Trauma
  • Post-surgical state
  • Certain medications
    • Chemotherapy agents
    • Certain anti-hypertensives
    • Certain diuretics

Clinical Features

  • Acute severe pain
  • 1st MTPJ most commonly affected (75% of first attacks)
  • 90% of chronic gout sufferers have MTPJ involvement at some stage
  • Ankle commonly affected
  • Lesser MTPJs, midtarsal, and subtalar joints usually spared

Chronic Gout

  • Large soft tissue deposition of monosodium urate (gouty tophi)
  • Severe joint destruction possible

Investigations

Blood Tests

  • May or may not show elevated uric acid levels

Joint Aspiration

  • Needle-shaped monosodium urate crystals
  • Strongly negatively birefringent under polarised light microscopy

X-Ray Findings

  • Erosions on both sides of the joint
  • Large soft tissue swelling around the joint
  • Erosions away from the joint

Management

Medical

  • NSAIDs for acute flare-ups
  • Allopurinol for prevention
    • Can precipitate gout if dose is too high

Surgical

  • Arthrodesis if MTPJ is destroyed and symptomatic

Pseudogout

Location

  • Knee most common
  • Any joint in the foot & ankle can be affected, unlike gout

X-Ray Findings

  • Chondrocalcinosis
  • Rare to get erosive joint destruction

Joint Aspiration

  • Calcium pyrophosphate crystals of varied shape
  • Weakly positive birefringence under polarised light microscopy

Management

  • Symptomatic treatment with NSAIDs, rest, and activity modification

Seronegative Spondyloarthropathies

General Features

  • Hallmark: Lack of rheumatoid factor
  • Affect enthuses more than articular joints

Main Presenting Symptoms

  • Achilles tendinopathy
  • Tibialis posterior tendinopathy
  • Plantar fasciitis

Psoriatic Arthritis

  • Can cause joint destruction
  • In foot, it typically affects lesser toe DIPJs
    • Pencil-in-cup erosions on X-ray
    • Nail pitting
    • Dactylitis (sausage digits)

Management

  • Symptomatic treatment
  • Joint fusion or excision if necessary
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