Chondrocalcinosis and other calcifications.

Less than 30 years ago, McCarty and others first described a syndrome which presented with gout-like attacks of arthritis but was due to CPPD crystals instead of urate crystals. They termed the condition "pseudogout." It was noted that this was often associated with chondrocalcinosis and it was commonly held that cartilage calcification had to be present if the diagnosis was to be suggested on the basis of the radiographic findings. Subsequently, a clinical and radiographic pattern has emerged in which the diagnosis of CPPD deposition disease can be suggested in the absence of chondrocalcinosis. This condition is termed pyrophosphate arthropathy and is differentiated from degenerative disease by the pattern and distribution of the joint disease. It is important to recognize CPPD deposition disease because of its association with other diseases, such as hemochromatosis and hyperparathyroidism. Although painful periarticular tendinous calcification (peritendinitis calcarea) resulting from the deposition of calcium HA crystals has long been recognized, it has only recently been discovered that intra-articular HA can be associated with an acute inflammatory synovitis. Additionally, patients are now being identified who have CPPD deposition at one anatomic location and HA deposition at another. Differentiation of these various types of crystal-induced arthropathies should lead to more effective therapy in the future.