Objective  To approach the expression and significance of connection tissue growth factor (CTGF) in articular cartilage after full-thickness osteochondral defect on the medial femoral condyle in young and adult rabbits model.   Methods  Totally 25 young (at an age from 10 to 12 weeks) and 25 adult New Zealand white rabbits (at an age from 34 to 39 weeks) were randomly divided into 5 groups (n=5)

control group

24-hour

1-week

4-week and 8-week after full-thickness cartilage injury groups. A rabbit model of spontaneous healing of full-thickness cartilage defect in the medial femoral condyle in both knees was reproduced. Macroscopic and histological morphous of repairs were observed in each age group during repair. mRNA and protein expression of CTGF were detected with RT-PCR and immunohistochemistry

respectively.   Results  The morphologically good repairs with hyaline-like cartilage appearance were observed in young rabbit

but formation of fibrous tissue in adult rabbit. The expression of CTGF mRNA was detected in all groups. Expression of CTGF mRNA was significantly higher in young rabbit than in adult rabbits (P0.05). The immunohistochemical results showed that the expression of CTGF was positive in all groups

and located in the middle and deep zones.   Conclusion  Young rabbits show better specialization of the repair tissue than adult animals accompanied with high expression of CTGF mRNA. CTGF may play a role in the repair of articular cartilage injury.