Challenges in computational fluid dynamics applications for bone tissue engineering.

Tiago Pires,John W C Dunlop,André P G Castro,Paulo Rui Fernandes

doi:10.1098/rspa.2021.0607

Abstract

Bone injuries or defects that require invasive surgical treatment are a serious clinical issue, particularly when it comes to treatment success and effectiveness. Accordingly, bone tissue engineering (BTE) has been researching the use of computational fluid dynamics (CFD) analysis tools to assist in designing optimal scaffolds that better promote bone growth and repair. This paper aims to offer a comprehensive review of recent studies that use CFD analysis in BTE. The mechanical and fluidic properties of a given scaffold are coupled to each other via the scaffold architecture, meaning an optimization of one may negatively affect the other. For example, designs that improve scaffold permeability normally result in a decreased average wall shear stress. Linked with these findings, it appears there are very few studies in this area that state a specific application for their scaffolds and those that do are focused on in vitro bioreactor environments. Finally, this review also demonstrates a scarcity of studies that combine CFD with optimization methods to improve scaffold design. This highlights an important direction of research for the development of the next generation of BTE scaffolds.

Highlights

Bones are some of the most important tissues in the human body, being responsible for providing structural support, protecting important internal organs and maintaining mineral homeostasis
The papers discussed in this review have demonstrated how changes to the material, manufacturing process or geometry of a given scaffold may significantly influence its properties
These studies have demonstrated how the porosity of a scaffold is fundamental in determining its fluidic properties: more porous scaffolds are more permeable but have overall lower wall shear stress (WSS)

Summary

Introduction

Bones are some of the most important tissues in the human body, being responsible for providing structural support, protecting important internal organs and maintaining mineral homeostasis. Scaffolds are porous support matrixes designed to allow cell growth, while maintaining the mechanical properties inherent to bone tissue. These factors, in turn, translate to more favourable conditions for cellular growth Another important parameter to study during a scaffold’s design is wall shear stress (WSS) that affects the cells inside the scaffold. One of the most important types of simulations in BTE is computational fluid dynamics (CFD), which allows the study of the fluid passing through the scaffold (the study of the permeability, fluid velocity and WSS), permitting a better understanding of how each scaffold geometry influences the cell growth process [15,16]. By Rouhollahi et al [38] who used this computational method to determine the average pore size and pore distribution in Freeze-Cast scaffolds and the paper by Chappard et al [37] who used CFD to determine the permeability of different granule biomaterials for mandible scaffolds

Current applications of CFD in BTE

Beyond CFD

Findings

Conclusion