Interfacial fracture toughness of tissue-biomaterial systems.

Tissue-biomaterial interfacial bonding strength plays a significant role in the success of the biomaterials used for load-bearing orthopedic prostheses. To assess the interfacial bonding strength, this study examined a fracture mechanics approach using a bilayer compact sandwich (BCS) specimen, in which a bilayer coupon comprising the interface between tissue and biomaterial was sandwiched between two holders. First, the theoretical basis for measuring interfacial fracture toughness using the BCS specimen was developed. Next, the effect of finite interlayer thickness on the measurements was addressed and a correction factor was determined using finite element analysis techniques. Accordingly, the theoretical solution was modified to account for the effect of the interlayer thickness. Finally, using a bone to bone-cement interface the BCS technique was empirically verified in terms of overall size, material combination, and interlayer thickness. It is expected that the BCS technique will provide an effective means for researchers to study and analyze tissue-biomaterial interfaces.