Mechanical anisotropy of titanium scaffolds

Abstract

Abstract:The clinical performance of an implant, e.g. for the treatment of large bone defects, depends on the implant material, anchorage, surface topography and chemistry, but also on the mechanical properties, like the stiffness. The latter can be adapted by the porosity. Whereas foams show isotropic mechanical properties, digitally modelled scaffolds can be designed with anisotropic behaviour. In this study, we designed and produced 3D scaffolds based on an orthogonal architecture and studied its angle-dependent stiffness. The aim was to produce scaffolds with different orientations of the microarchitecture by selective laser melting and compare the angle-specific mechanical behaviour with an in-silico simulation. The anisotropic characteristics of open-porous implants and technical limitations of the production process were studied.

A flexible design framework to design graded porous bone scaffolds with adjustable anisotropic properties

“…By developing a flexible design framework to design scaffolds, the long-term objective of the present approach is to provide better support for tissue growth and repair, or more closely mimic the form and function of a missing or damaged body part. The identification of the most suitable porous structure for a given clinical application still remains a challenge, since the key requirements involve both morphological considerations such as porosity and mechanical effective properties such as compressive modulus or anisotropy (Rüegg et al, 2017). These two parameters are obviously strongly related for cellular structures (Gibson, 2005), and the influence of scaffold porosity on its effective mechanical properties has been widely reported (Bandyopadhyay et al, 2010;Karageorgiou and Kaplan, 2005;Poh et al, 2019).…”

“…It is worthy to emphasize that the computed apparent properties for the different configurations are far lower than initial bone properties, due to the low elastic properties of the constitutive resin of the scaffold considered in the present study. This has led different authors to prefer scaffold based on metallic powders (Liao et al, 2021a;Rüegg et al, 2017), while the present approach concerns regenerative medicine which requires biodegradable polymeric materials (Peltola et al, 2008;Wang et al, 2020;Weisgrab et al, 2020).…”

“…The emergence of additive manufacturing has permitted to design various scaffold architectures, essentially based on the 3D periodic repetition of a unit cell (UC) to form porous 3D structures (Afshar et al, 2016;Bahraminasab, 2020;Bobbert and Zadpoor, 2017;Deng et al, 2021;Dias et al, 2012;Donate et al, 2020;Fernandes et al, 2020;Kolken et al, 2020;Liu et al, 2018;Su et al, 2021;Wang et al, 2020;Yoo, 2011). As a consequence of this periodic design framework, the resulting 3D porous scaffolds generally exhibit isotropic properties, while native bone tissue is far from being isotropic (Li et al, 2013) and anisotropic behavior may be suited for specific applications (Rüegg et al, 2017). In opposition to these perfectly periodic structures, it has been reported that scaffolds with pore size gradients offer better seeding efficiency than homogeneous scaffolds (Sobral et al, 2011) and enhance the diffusion of nutrients from the core to the periphery of scaffolds (Ahn et al, 2010).…”

Structural and Material Determinants Influencing the Behavior of Porous Ti and Its Alloys Made by Additive Manufacturing Techniques for Biomedical Applications

“…Therefore, increasing the laser spot size allows using high power lasers without overheating, but this may compromise the precision and surface roughness of the parts [28]. The strength of additively manufactured Ti parts is also dependent on the build orientation [17,152,153]. In [71], the static compressive properties and fatigue lives of the octahedron scaffolds were superior to those of tetrahedron ones.…”