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