Análise fotocolorimétrica computadorizada dos efeitos da betametasona intraAnálise fotocolorimétrica computadorizada dos efeitos da betametasona intraAnálise fotocolorimétrica computadorizada dos efeitos da betametasona intraAnálise fotocolorimétrica computadorizada dos efeitos da betametasona intraAnálise fotocolorimétrica computadorizada dos efeitos da betametasona intraarticular sobre a concentração de proteoglicanos da matriz cartilaginosa de articular sobre a concentração de proteoglicanos da matriz cartilaginosa de articular sobre a concentração de proteoglicanos da matriz cartilaginosa de articular sobre a concentração de proteoglicanos da matriz cartilaginosa de articular sobre a concentração de proteoglicanos da matriz cartilaginosa de joelhos leporinos: influência do número de injeções intra-articulares joelhos leporinos: influência do número de injeções intra-articulares joelhos leporinos: influência do número de injeções intra-articulares joelhos leporinos: influência do número de injeções intra-articulares joelhos leporinos: influência do número de injeções intra-articulares To study the effects of repeated injections of betamethasone on proteoglycan concentration in the articular cartilage of normal knees of Californian rabbits of both sexes. Methods Methods Methods Methods Methods: Eighty animals were randomly divided into eight groups of ten animals each. Three control groups (saline solution injected or not) and five study groups -therapeutical doses, repeated or not, of betamethasone injected into the right knee of each animal at weekly intervals. After eight days from the last injection, sections of articular cartilage from tibial plateaus collected from weight-bearing surfaces were stained with hematoxylin and eosin for light microscopy analysis and with safranin O for the proteoglycan content assay. The staining intensity of safranin O was quantified by histomorphometry using an Olympus BX 50 microscope and a microcomputer with the Image Pro-plus 4.5Ò software. Results Results ResultsResults Results: Animals receiving one, two and four betamethasone injections showed no differences when compared to normal controls. Animals receiving six and eight injections had a significant decrease in safranin O staining intensity (p < 0.05) as compared to the control groups and the other study groups. Conclusion Conclusion Conclusion Conclusion Conclusion: A decrease in the concentration of articular cartilage proteoglycans dependent on repeated betamethasone injection was effectively demonstrated.