Carrageenin-induced arthritis. I. The effect of intraarticular carrageenin on the chemical composition of articular cartilage.

A single intraarticular injection of carrageenin into rabbit knee joints initiated a localized synovial inflammatory response. This response was accompanied by a 20% loss of proteoglycan from the articular cartilage within 24 hours and by a further 30-60% loss within 5-7 days. The chondrocytes replaced the lost proteoglycan within 42 days. More than two injections caused only a further small decrease in proteoglycan content; the cartilage was then unable to replace the lost proteoglycan. The absence of recovery coincided with the appearance of erosion of the cartilage surface.