Kinetics of extraction of proteoglycans from human cartilage.

Fifty-one uniformly sliced human patellar cartilage specimens were extracted with physiologic buffer containing inhibitors. Galactosamine-rich proteoglycans were more easily extracted than glucosamine-rich proteoglycans. Extraction occurred in 2 phases. There was a large proteoglycan extraction during the first 30 minutes, followed by a steady loss proportional to the square root of time. The amount of proteoglycans extracted during phase 1 was approximately half that of phase 2. Extraction of proteoglycans varied with age, structural integrity, and cartilage thickness. Intact osteoarthritic cartilage had normal proteoglycan extraction.