Mechanical studies of the bone bioglass interfacial bond.

A series of squirrel monkeys received segmental femoral replacements in a study of the strength of the interface developed between the implant and bone. Implants were either made completely of bioglass-ceramic, or 316L stainless steel with a flame-sprayed coating of bioglass. Fracture torque, energy at fracture, and shear stress at failure were compared to values obtained from a control group of pairs of tibias. Femurs containing bulk bioglass-ceramic implants showed about a 25% difference in strength compared to the opposite bone, while femurs containing flame-sprayed implants exhibited extremely low structural strength. While the strength of the metal-glass bond was very low (less than 500 kgf/cm2), the bone-bioglass bond was found to be at least as strong as the bioglass-ceramic, and at least 3/4 as strong as the host bone.