Form of arthritis that results from deposits of calcium pyrophosphate crystals provoking an inflammatory response

Aetiology

• Most common in the elderly
  • Chondrocalcinosis increases with age
    • Chondrocalcinosis: calcium pyrophosphate deposition occurs in cartilage and other soft tissues in the absence of acute inflammation
    • Both pseudogout and chondrocalcinosis come under the umbrella of Calcium Pyrophosphate Deposition disease (CPPD)
  • Related to osteoarthritis - calcium deposition can occur in some cases of OA
• Affects fibrocartilage - knees, wrists, ankles

Other risk factors

• Injury or previous joint surgery
• Hyperparathyroidism
• Haemochromatosis
• Hypomagnesaemia
• Hypophosphataemia
• Acute attacks may be precipitated by intercurrent infection

Clinical presentation

• Patients typically present with an acute monoarthritis - swollen, painful, warm joint
• Knee most commonly affected
• Patients may display an acute systemic illness with fever and general malaise

Investigations

• Joint aspiration: the key investigation
  • Shows positively birefringent rhomboid-shaped crystals made of calcium pyrophosphate on polarised microscopy
• Bloods: marked rise in inflammatory markers
• Bloods: to rule out secondary causes of pseudogout (particularly important in younger patients)
  • Ferritin, iron-binding studies, bone profile, alkaline phosphatase

Management