Morphological and biochemical studies of the cartilage in the diabetic rat--a model for metabolism-induced arthritis

Abstract

Because of its general effects on connective tissue metabolism diabetes mellitus is becoming more and more important in the orthopaedic field. For investigation of morphologic changes in the cartilage a model of streptozotocin-induced diabetes was used in 80 rats. Studies were performed by light-, scanning- and transmission-electron microscopy and by biochemical analysis of proteoglycan and collagen metabolism. Three months after onset of diabetes the chondrocytes show increased metabolic activity and at the same time first stage regressive changes. The morphologic changes correlate with a significant decrease of hexosamine content in the cartilage. There is no evidence for any disturbance of collagen metabolism at that time. After seven months the cartilage is widely necrotic, the collagen fibers are swollen and show almost total loss of their microstructure. There is no sign for reparation of the necrotic zones at this time. It is most remarkable that in many specimen crystal deposits are found just below the cartilage surface which from the TEM-findings look very much like calciumpyrophosphate crystals. The morphologic and biochemical results show that in the rat diabetes leads to a special type of cartilage changes with crystallic arthropathy which seems to be a valuable model for the study of metabolic osteoarthrosis.