Numerical Evaluation and Prediction of Porous Implant Design and Flow Performance.

Jian Li,Yubo Fan,Yingying Zhang,Diansheng Chen,Huiqin Luan

doi:10.1155/2018/1215021

Abstract

Porous structure has been widely acknowledged as important factor for mass transfer and tissue regeneration. This study investigates effect of aimed-control design on mass transfer and tissue regeneration of porous implant with regular unit cell. Two shapes of unit cells (Octet truss, and Rhombic dodecahedron) were selected, which have similar symmetrical structure and are commonly used in practice. Through parametric design, porous scaffolds with the strut sizes of φ 0.5, 0.7, 0.9, and 1.1mm were created, respectively. Then using fluid flow simulation method, flow velocity, permeability, and shear stress which could reflect the properties of mass transfer and tissue regeneration were compared and evaluated, and the relationships between porous structure's physical parameters and flow performance were studied. Results demonstrated that unit cell shape and strut size greatly determine and influence other physical parameters and flow performances of porous implant. With the increasing of strut size, pore size and porosity linearly decrease, but the volume, surface area, and specific surface area increased. Importantly, implant with smaller strut size resulted in smaller flow velocity directly but greater permeability and more appropriate shear stress, which should be beneficial to cell attachment and proliferation. This study confirmed that porous implant with different unit cell shows different performances of mass transfer and tissue regeneration, and unit cell shape and strut size play vital roles in the control design. These findings could facilitate the quantitative assessment and optimization of the porous implant.

Highlights

Porous structure has been widely acknowledged as important factor to avoid stress shielding and promote mass transfer, cell adhesion, and differentiation for bone tissue engineering (BTE), which could be manufactured by conventional fabrication techniques [1], such as gas foaming, solvent casting, particle leaching, fiber meshes, and freeze drying [2]
RD scaffolds displayed bigger pore size and porosity than Octet truss (OT) scaffolds on the same strut size, but for the volume, surface area, and specific surface area, OT scaffolds seemed to be bigger than RD
This study confirmed that different unit cells and strut size result in different physical parameters [4], unequal flow performance of porous scaffolds for nutrient delivery and tissue regeneration [34]

Summary

Introduction

Porous structure has been widely acknowledged as important factor to avoid stress shielding and promote mass transfer, cell adhesion, and differentiation for bone tissue engineering (BTE), which could be manufactured by conventional fabrication techniques [1], such as gas foaming, solvent casting, particle leaching, fiber meshes, and freeze drying [2]. These methods should lead to irregular porous structure and uncontrollable interconnectivity, which have many flaws and potential risks for mechanical properties and biological properties, such as stress concentration and fatigue damage. It has been reported in the literatures that physical parameters of porous structure, such as pore size, porosity, volume, surface area, and specific

Methods

Results

Discussion

Conclusion