Challenges in computational fluid dynamics applications for bone tissue engineering

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.

Keywords: biomechanics; bone tissue engineering; computational fluid dynamics; optimization; scaffolds.

Figure 1.

Examples of possible scaffold geometries for bone tissue engineering (BTE): (a) lattice geometry (adapted from [5]) and (b) triply periodic minimum surfaces (TPMS) [6]. (Online version in colour.)

Figure 2.

Fluidic properties studied using CFD simulations: (a) wall shear stress (WSS) along the walls of the scaffold (adapted from [26]) and (b) tortuosity of the fluid flow through the scaffold (adapted from [27]). (Online version in colour.)

Figure 3.

Average WSS in scaffolds with different pore diameters and fluid inlet velocities (adapted from [32]). (Online version in colour.)

Figure 4.

Surface shear strain of: (a) a 0–90 scaffold with no flow; (b) a 0–90 scaffold with flow; (c) a 0–90 offset scaffold with no flow; and (d) a 0–90 offset scaffold with flow (adapted from [60]). (Online version in colour.)

Figure 5.

Maximum mechanical stress and maximum WSS in function of the scaffold porosity (adapted from [53]). (Online version in colour.)

Figure 6.

Types of possible scaffold optimization: (a) topology optimization and (b) shape optimization.