[Diagnosis and treatment of calcium pyrophosphate crystal-induced arthropathy]

Calcium pyrophosphate dihydrate deposition (CPPDD) disease is the term used to describe a group of common and potentially severe metabolic arthropathies. In these, CPPD crystals form and are deposited in the cartilage matrix (chondrocalcinosis) and induce inflammatory and/or destructive mechanisms. Most cases are idiopathic, but hyperparathyroidism, hemochromatosis, hypomagnesemia and hypophosphatemia can promote or cause chondrocalcinosis. Early disease (with onset before the age of 60 years) thus requires that the patient be examined for these metabolic conditions, particularly hemochromatosis. The prevalence of CPPDD disease in the general population increases with age, being 10-15% in the age group 65-75 years and more than 40% in the over-80s. Although frequently asymptomatic, chondrocalcinosis can involve severe acute attacks of inflammatory arthritis (pseudogout) and also various types of chronic arthropathy including pseudorheumatoid arthritis, pseudo-osteoarthritis, and pseudoneuropathic joint disease. CPPD crystals can also be deposited in the bursae, ligaments, and tendons and generate inflammation and/or ruptures. The diagnosis is based on synovial fluid analysis (positively birefringent CPPD crystals visualized by compensated polarized light microscopy) and X-rays (punctate and linear radiodense areas in fibrocartilage and hyaline cartilage). Treatment is primarily symptomatic, since there is no known drug that can prevent progression of the joint destruction). Nonsteroid anti-inflammatory drugs (NSAIDs) and intra-articular or systemic glucocorticoids (amounts must be only small if use is prolonged) are the most useful treatments. Colchicine can be effective in recurring pseudogout, and magnesium can be used prophylactically. In a small uncontrolled series methotrexate was effective and aroused interest; it can be used when other treatments fail.