The Fatigue Design of a Bone Preserving Hip Implant With Functionally Graded Cellular Material

An orthopaedic hip implant is expected to support dynamic forces generated by human activities. To avoid progressive and localized damage caused by daily cyclic loading, the prosthesis is to be designed for fatigue under high cycle regime. Recently, a methodology has been developed to design a novel hip implant made of a cellular material with a periodic microarchitecture [1]. In contrast to current hip replacement implants typically made out of a fully solid material, which can be coated with a porous layer, this implant is completely porous. The microarchitecture of the material is a lattice displaying graded property distribution. The advantage of controlling the microarchitecture is twofold. First, the overall implant can be designed to be more compliant, which reduces stress shielding and bone resorption [2]. Second, the material porosity can be optimized to reduce bone-implant interface stresses, thereby lowering implant micromo-tion. Although encouraging, these results...