Calcium crystal-associated arthritides.

Articular calcium-containing crystals cause calcium pyrophosphate dihydrate (CPPD) deposition disease, basic calcium phosphate (BCP)-associated syndromes, and calcium oxalate arthritis. During the past year, important contributions have been made to our understanding of CPPD- and BCP-related syndromes. Clinical studies of CPPD deposition disease underscore the importance of extra-articular and spinal CPPD deposits, and question the association between hypothyroidism and chondrocalcinosis. Laboratory reports add key information to our current paradigms of CPPD crystal formation and CPPD-induced inflammation. Several interesting new therapeutic interventions may arise from this work. A case collection of BCP-related syndromes emphasizes the need for considering this diagnosis in young healthy patients with acute arthritis or periarthritis.