Pseudogout

Definition

  • CPPD deposition disease is calcium pyrophosphate crystal deposition in articular and periarticular tissues
  • Chondrocalcinosis is radiographic calcification of hyaline cartilage or fibrocartilage

Classification

  • Asymptomatic deposition
  • Osteoarthritis with CPPD
  • Acute CPP crystal arthritis (pseudogout)
  • Chronic CPP inflammatory arthritis

Epidemiology

  • Prevalence rises steeply with age, uncommon before 60 unless metabolic or familial
  • Onset before about 55 years prompts a metabolic screen

Aetiology

  • Excess chondrocyte pyrophosphate combines with calcium to form crystals
  • Familial forms involve ANKH, which regulates pyrophosphate transport
  • Shed crystals activate the NLRP3 inflammasome, releasing interleukin 1 beta
  • Haemochromatosis, with hook-like osteophytes on the second and third metacarpal heads
  • Hyperparathyroidism and hypomagnesaemia, including Gitelman syndrome
  • Hypophosphatasia, with low alkaline phosphatase
  • Osteoarthritis, previous joint trauma and meniscectomy

Clinical Features

  • Acute hot swollen joint, sometimes with fever, mimicking septic arthritis
  • Triggered by surgery (especially parathyroidectomy), illness, trauma and intra-articular hyaluronic acid
  • Chronic arthritis in atypical joints, radiocarpal, glenohumeral, patellofemoral and MCP
  • Crowned dens syndrome, acute neck pain and fever from odontoid calcification

Investigations

CPPD, radiograph showing chondrocalcinosis
Radiograph showing chondrocalcinosis. Image by Taokinesis (Pixabay profile), Wikimedia Commons, CC0.
  • Aspiration shows weakly positively birefringent rhomboid crystals, blue when parallel to the compensator
  • Gout crystals are strongly negatively birefringent needles
  • Always send Gram stain and culture, as infection can coexist
  • Metabolic screen of calcium, PTH, magnesium, phosphate, ALP, iron studies and thyroid function
  • Chondrocalcinosis in knee menisci, triangular fibrocartilage and pubic symphysis
  • Isolated patellofemoral arthritis, large subchondral cysts and SLAC wrist
  • Ultrasound shows a hyperechoic band within hyaline cartilage

Differential Diagnosis

  • Septic arthritis and gout
  • Rheumatoid arthritis and inflammatory osteoarthritis flare
  • Basic calcium phosphate (hydroxyapatite) arthropathy

Management

  • Acute attacks treated with aspiration, rest, ice and NSAIDs or colchicine
  • Intra-articular corticosteroid once infection is excluded
  • Systemic corticosteroid for polyarticular attacks or when other agents are contraindicated
  • Interleukin 1 inhibitors for refractory disease
  • Treat metabolic causes, although chondrocalcinosis does not regress
  • No equivalent of urate-lowering therapy
  • Low dose colchicine prophylaxis, magnesium for hypomagnesaemia
  • Arthroplasty for end-stage arthritis
  • Postoperative crystal flares mimic infection, so aspirate and culture

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.