Clinical aspects of calcium pyrophosphate dihydrate crystal deposition.

CPPD deposition occurs in a wide variety of clinical settings, most commonly as an age-related phenomenon in the absence of other joint abnormality. Although our knowledge of CPPD and other intra-articular particles has increased in the last decade, the role of CPPD remains unclear. The paradox of asymptomatic deposition of phlogistic crystals, the wide spectrum of clinical presentation, and the lack of disease specificity, however, have challenged recognition of pyrophosphate arthropathy (PA) as a separate, distinct disease entity and led to reappraisal of earlier concepts of crystal deposition disease. In this article, clinical aspects of PA will first be presented; the validity of PA as a discrete arthropathy will then be discussed.