Joint inflammation caused by calcium pyrophosphate crystals

Demographics

• Common, >50y, increase with age. 60% by 85y.

Aetiology

• Many types
  • Sporadic/Idiopathic*, Hereditary & Secondary.
  • Secondary – trauma, hemochromatosis, hyperparathyroidism etc.
  • Crystals in cartilage, menisci → inflammation & damage.

Pathophysiology

• Deposition of calcium pyrophosphate dihydrate (CPP or CPPD) crystals in articular cartilage → paroxysmal joint inflammation and cartilage destruction → inflammatory arthritis

Risk Factors

• Joint trauma
• Metabolic disorders e.g. hyperparathyroidism, haemochromatosis
• Idiopathic most common

Clinical Features

• commonly asymptomatic, can be acute / subacute / chronic arthritis.
• presents similar to gout, except most commonly in knee