Multiscale modeling and optimization of additively manufactured composite bone implants using the boundary element method and molecular dynamics

Abstract

Bone implants are conventionally made of metallic materials, such as stainless steel and titanium alloys, due to their satisfactory mechanical strength and corrosion resistance. However, the mismatch of mechanical properties between bone and metallic implant may cause stress shielding at the surrounding tissue, which can lead to bone resorption, and eventual looseness or failure of the implant. Moreover, metallic implants may have problems such as the release of harmful metallic ions, inflammatory reactions, and incompatibility with magnetic resonance imaging. The use of composite materials is attractive because of their excellent strength-to-weight ratio, and the possibility to tailor their material properties to meet specific design requirements. Furthermore, Additive Manufacturing (AM) techniques can rapidly produce complex composite geometries. Nevertheless, the literature on AM of composite materials is still scarce, and AM of composite bone implants is an entirely new research field. This work will use a new multiscale approach to investigate the thermal-mechanical behavior of additively manufactured composite bone implants. The resulting models will cover the continuum and atomistic scales using, respectively, the boundary element method and molecular dynamics. Our main objective is to optimize composite bone implants to replicate the material properties of the host bone tissue, enhancing biocompatibility, reducing stress shielding, and minimizing the patient's discomfort. The 3D geometry and mechanical properties of the host bone will be acquired via computed tomography. (AU)