Fracture Toughness Testing of In Vivo Aged Biomaterials

Abstract

ABSTRACTAlthough mechanical property characterization of materials for loadbearing implant applications is recognized as a necessary prerequisite to theirin vivouse, tests are usually restricted toin vitrosituations becaus-of specimen size and cost limitation. Thisstid7'Jescribes a fracture toughness test that uses small specimens that can be conveniently placed in intermuscular positions in laboratory rats. The method is illustrated for the evaluation of two orthopaedic biomaterials namely bone cement and a filled composite (hydroxyapatite-filled polyethylene). The results indicated little mechanical degradation of the bone cement after 120 daysin vivobut a significant change in the filled polyethylene composite after only 70 days in vivo.