Development of a shear test system for measuring the interfacial strength of osteochondral grafts from rabbits of different skeletal maturity

Abstract

Osteochondral interface is important in stabilising mechanically dissimilar tissues. Skeletal maturity has been found important in determining the shear failure characteristics in bovine patella but data for small animals such as rabbits are not available, making the engineering design for osteochondral interface lack of reference. In this study, a shear test system for rabbit osteochondral grafts is developed and the shear failure characteristics of samples from immature and mature rabbits are compared. In order to validate the system, the failure stress of growth plate in hip joints of immature rabbits is measured by using the same specifications available in the literature. It was noted that the failure mechanism of osteochondral grafts in the mature knee joints is different from that of the immature ones while the failure parameters were also significantly different between the immature and the mature groups. These results echoed with the only available data on bovine patella. The current study provides baseline data on rabbit osteochondral interfacial strength, serving as an important reference for engineering osteochondral interface, and provides evidence on the stabilising effect of the calcified cartilage interface zone in the mature osteochondral grafts, therefore suggesting the necessity to engineer a functional interface for future osteochondral tissue engineering.