Characterization and Design of Bone Tissue Scaffolds

Abstract

Biological and mechanical functions are sometimes two conflicting characteristics of bone tissue scaffolds, thus a trade-off between these two properties is critical. An ideal scaffold not only should be strong but also must possess adequate permeability to allow efficient transport of oxygen and nutrients. Mechanical stimulation is another important parameter known to control bone tissue formation in the scaffolds. Therefore, effective tools capable of reliably characterising and optimising different material properties of bone scaffolds are necessary in order to enhance bone regeneration outcome. In this thesis, the extended finite element method (XFEM) was implemented to accurately predict fracture strength of ceramic scaffolds. The yielding behaviours of polymeric scaffolds were also studied by means of finite element method (FEM). The comparison between numerical results and in-house experimental data confirmed the effectiveness of these techniques. Moreover, numerical simulations were implemented to optimise the strength and permeability of ceramic scaffolds fabricated by direct ink writing method. Furthermore, the effect of scaffolds’ architectural design on the volume and functionality of newly formed bone was demonstrated in-vivo. To reduce computational cost for characterization of strain distribution in scaffolds, a simple homogenization modelling approach was developed. The proposed homogenization approach was applied to characterize strain energy distribution within scaffolds implanted in segmental defects in sheep tibia in-vivo. A direct relationship between the pattern of the strain energy distribution in each scaffold and resulted bone formation pattern was observed in-vivo. In conclusion, the outcomes generated in this thesis are expected to establish robust numerical frameworks for characterisation of different structural properties related to bone tissue scaffolds.