Proteoglycan aggregation in injured articular cartilage. A comparison of healing lacerated cartilage with osteoarthritic cartilage.

Canine knee cartilage which had been damaged by laceration with a scalpel down to subchondral bone (Model A) and knee cartilage from dogs in whom osteoarthritis had been induced by transection of the anterior cruciate ligament by arthrotomy (Model B) were compared 7 weeks after the surgical procedures. Cartilage from the operated knees in Model A was hypocellular and showed extensive fibrosis, while samples from Model B showed moderate fibrillation and osteophyte formation. (In both cases water content was increased and uronic acid content decreased in cartilage from the operated knees.) Despite the much greater pathomorphologic changes in Model A, aggregation of 35S proteoglycans synthesized in culture was unchanged by the operation, while in Model B the proportion of proteoglycans existing as aggregates was diminished.