Changes in articular cartilage after intra-articular injections of methylprednisolone acetate in horses

• Published in: American journal of veterinary research Vol. 50; no. 10; p. 1733
• Main Authors: Chunekamrai, S. (Cornell University, Ithaca, NY), Krook, L.P, Lust, G, Maylin, G.A
• Format: Journal Article
• Language: English
• Published: United States 01.10.1989
• Subjects: ACETATE; ACETATES; ACETATOS; Animals; Anti-Inflammatory Agents - administration & dosage; Anti-Inflammatory Agents - pharmacology; ARTICULACIONES; ARTICULATION; CABALLOS; CARTILAGE; Cartilage, Articular - analysis; Cartilage, Articular - cytology; Cartilage, Articular - drug effects; Cartilage, Articular - metabolism; CARTILAGO; CHEVAL; Collagen - biosynthesis; EFECTOS SECUNDARIOS; EFFET SECONDAIRE; Fibronectins - analysis; GLUCOCORTICOIDE; GLUCOCORTICOIDES; GLUCOCORTICOIDS; HORSES; Horses - anatomy & histology; Hydroxyproline - analysis; INJECTION; Injections, Intra-Articular - veterinary; INYECCION; JOINTS; Methylprednisolone - administration & dosage; Methylprednisolone - analogs & derivatives; Methylprednisolone - pharmacology; Proteoglycans - biosynthesis; SIDE EFFECTS; Synovial Fluid - drug effects; Viscosity
• ISSN: 0002-9645; 1943-5681

Eight mature horses with no prior signs of joint disease or history of intra-articular therapy were treated with 8 weekly intra-articular injections of methylprednisolone acetate. Treatments were given at a dose of 120 mg/joint into the right radiocarpal and intercarpal joints, with the left joints as untreated controls. Articular cartilage samples were obtained at necropsy 1, 4, and 8 weeks after the last injection. Compared with controls, cartilage from injected joints had a loss of hematoxylin basophilia and decreased intensity of staining in safranin O fast green dye. Chondrocyte necrosis and hypocellularity were observed in all samples of cartilage from treated joints. Proteoglycan content and its rate of synthesis were reduced. There was a progressive loss of proteoglycan content, whereas proteoglycan synthesis increased somewhat 4 and 8 weeks after treatment. Collagen content was unchanged, but its rate of synthesis was markedly inhibited. Collagen synthesis did not recover, but remained decreased at 5 to 15% of the values from untreated cartilage. Water percentage was increased, but fibronectin content was not significantly different. A single injection of methylprednisolone acetate was also given into the right metacarpophalangeal joints of 3 of the 8 horses in this group, with the left joints serving as untreated controls. Sixteen weeks after the treatment, cartilage of the treated joints had a loss of histochemical staining and proteoglycan content was reduced to 50% of control values. The mean rate of proteoglycan synthesis and mean fibronectin content were increased, but the differences were not statistically significant (P greater than 0.05). Other variables were essentially unchanged.