Foam-reinforced elderly human tibia approximates young human tibia better than porcine tibia: a study of the structural properties of three soft tissue fixation devices

BACKGROUND: Because there is an insufficient supply of young human knees, an alternative is needed for evaluating anterior cruciate ligament reconstructions. The authors determined whether an elderly human tibia reinforced with foam is a better substitute for a young human tibia than a porcine tibia in this study of the tibialfixation of a soft tissue anterior cruciate ligament graft using 3 devices. HYPOTHESIS: A foam-reinforced elderly human tibia more closely approximates the performance of a young human tibia than porcine tibia. STUDY DESIGN: Biomechanical study. METHODS: Failure mode, stiffness, yield, and slippage were determined for a double-looped tendon graft fixed with either an interference screw, WasherLoc, or tandem washers in young human tibiae, foam-reinforced tibiae from elderly humans, and porcine tibiae. RESULTS: The stiffness and yield of interference screw and WasherLoc fixation in foam-reinforced tibiae more closely approximate those in young human tibiae than in porcine tibiae. Slippage of all combinations of tibiae and fixation devices was similar CONCLUSIONS: A foam-reinforced human tibia more closely approximates the performance of a young human tibia than that of porcine tibia in this study. CLINICAL RELEVANCE: Fixation devices should be tested in foam-reinforced tibiae from elderly humans rather than tibiae from large farm animals when the supply of young human knees is insufficient.