The Experimental Study Of Articular Cartilage Damage Induced By Intra-articular Injection Of Glucocorticosteroid

Objective: To investigate the change of collagen II and biomechanics in articular cartilage after intra-articular injection of glucocorticosteroid and study articular cartilage damage induced by injection of glucocorticosteroid. Methods: Twenty-four healthy Japanese white rabbits (weighted 2.0 ± 0.5kg) were divided randomly and evenly into an experimental(n=12)and a control(n=12)groups. In experimental group prednisolone acetate was injected into knee joint at a dose of 7.5mg/kg per week; in control group normal saline was injected into the knee joint at a dose of 0.375ml/kg per week. Each group dose volume was equal. Three rabbits of each group were killed at the times of 3,4,5,and 6th week during the experimental process. Femoral condyle and trochlea was taken from three rabbits of each group. All the specimens were stained with hematoxylin and eosin, safranin 0 and alcian blue, to compare the difference of the articular cartilage. Extracellular deposition collagen II was analyzed immunohistochemically with multiclonal antibodies and compare the difference of the relative gray value of collagen type II in the articular cartilage. Optic microscopic examinations were conducted to observe the pathological changes of articular cartilage of the knee of these rabbits. All the articular cartilages were biomechanical examination, to compare the difference of the values of maximal tensile stress.Results :1.Macroscopic observation: Without infected, the face of the articular cartilage was smooth and no crack . The articular cartilage was bright white in control group. From 3 to 6 weeks, in experimental group, the articular cartilagebecome rough and the color fade from white to gray-yellow gradually. The softened articular cartilage was detected. The more liquid were found in the joint as more injections of glucocorticosteroid administered.2 .Hematoxylin and eosin stain showed: In control group: The articular cartilage was stained evenly light blue. The superficial of articular cartilage was smooth. The articular cartilage was divided into four morphologically distinct zones: the superficial zone, the middle zone, the deep zone and calcified cartilage. The tidemark was intact. The shape and arrangements of all zone chondrocyte appear in order.In experimental group: The articular cartilage was stained light blue. From 3 to 6 weeks, staining showed loss of normal chondrocyte arrangement, the lesion of the articular cartilage degeneration gradually, the structure feature of articular cartilage was unclear and the tidemark defect varied by different degree from vague to broken to disappeared. The shape and alignment of chondrocyte were in disorder. Some chondrocyte become by different degree from small to trophy to clustered. The chondrocyte vacuole degeneration was detected. The number of chondrocyte was not found statistic significance with the control group. (P> 0.05).3 .Safranin-0 staining showed: In control group: From 3 to 6 weeks, cartilage matrix red stained evenly. The red stained become light gradually and unevenly in the experimental group, especially in rabbits with more times injection. Some area losing of staining was found. The matrix staining became decreased by different degree and the matrix staining far from control group and the red around the chondrocyte lacuna decreased by different degree.4. Collagen type II immunohistochemically with multiclonal antibodies: In control group: the collagen type II detected through the four layers in articular cartilage and was stained evenly dark yellow-brown. While the articular cartilage was...