[Identification of the crystals observed in the destructive arthropathies of chondrocalcinosis].

Study of the synovial membrane and cartilage demonstrating two destructive arthropathies of the knee diagnosed in subjects with articular pseudogout. Scanning electron microscopy reveals the presence of many crystals on the surface of the cartilage and the synovium and in the depth of the cartilage. These can be grouped into two families on the basis of dimensions and morphology. The first consists of those shaped like arrowheads and are large (80-100 microns long.) They were formally identified using Weissenberg's technique; dihydrated calcium hydrogenophosphate (CaHPO4.2H2O) is involved here. In the second family the crystallogenesis is different (prism or lozange-shaped) and the crystals themselves have not been identified with certainty because of their tiny size (20 microns). The hypothesis is proposed that the crystals of dihydrated calcium hydrogenophosphate properly belong to the destructive arthropathies of pseudogout; while not necessarily its cause, they may help explain its development.