AbstractAnin vivostudy of cartilage breakdown in mice was carried out by implanting living and dead, intact or finely minced autologous cartilage back into newly elicited inflammatory tissue of the original donor. At various time intervals, the implants were removed and their loss of proteoglycan and collagen analysed both histologically and biochemically. The results show that only a modest loss of proteoglycan and collagen occurs in the living intact cartilage. Severe loss of proteoglycan was detected in the minced living and dead intact cartilage. The present findings clearly demonstrate that mechanical damage during the mincing of cartilage predisposes this tissue to attack by various types of mediators known to degrade cartilage.