Influence of trypsin on the regeneration of hyaline articular cartilage.

A purely chondral lesion was inflicted at the medial or lateral femoral condyle of the knee joints of 54 adult male rabbits in order to study hyaline cartilage regeneration. The experimental group was given a sequential intraarticular instillation of trypsin and autologous blood, the control groups were given trypsin or blood or nothing. Only the experimental group (trypsin and autologous blood) showed hyaline cartilage regeneration in 2/3 of the cases examined. Apparently neither the healthy cartilage nor the synovial membrane suffered damage from the trypsin injection. A possible mechanism of cartilage regrowth may be the inhibition of chalones by the fermentative effect of trypsin, which stimulates the aggregation of thrombocytes and fibrin from the injected blood on the chondral lesion, thus initiating the regeneration of hyaline cartilage.