Cai Shengyong, Xi Juntong, Chua Chee Kai
School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China.
Methods Mol Biol. 2012;868:45-55. doi: 10.1007/978-1-61779-764-4_3.
Tissue engineering is the application of interdisciplinary knowledge in the building and repairing of tissues. Generally, an engineered tissue is a combination of living cells and a support structure called a scaffold. The scaffold provides support for bone-producing cells and can be used to heal or replace a defective bone. In this chapter, a novel bone scaffold design approach based on shape function and an all-hexahedral mesh refinement method is presented. Based on the shape function in the finite element method, an all-hexahedral mesh is used to design a porous bone scaffold. First, the individual pore based on the subdivided individual element is modeled; then, the Boolean operation union among the pores is used to generate the whole pore model of TE bone scaffold; finally, the bone scaffold which contains various irregular pores can be modeled by the Boolean operation difference between the solid model and the whole pore model. From the SEM images, the pore size distribution in the native bone is not randomly distributed and there are gradients for pore size distribution. Therefore, a control approach for pore size distribution in the bone scaffold based on the hexahedral mesh refinement is also proposed in this chapter. A well-defined pore size distribution can be achieved based on the fact that a hexahedral element size distribution can be obtained through an all-hexahedral mesh refinement and the pore morphology and size are under the control of the hexahedral element. The designed bone scaffold can be converted to a universal 3D file format (such as STL or STEP) which could be used for rapid prototyping (RP). Finally, 3D printing (Spectrum Z510), a type of RP system, is adopted to fabricate these bone scaffolds. The successfully fabricated scaffolds validate the novel computer-aided design approach in this research.
组织工程是跨学科知识在组织构建和修复中的应用。一般来说，工程化组织是活细胞与一种称为支架的支撑结构的组合。支架为成骨细胞提供支撑，可用于愈合或替代有缺陷的骨骼。在本章中，提出了一种基于形状函数和全六面体网格细化方法的新型骨支架设计方法。基于有限元法中的形状函数，使用全六面体网格来设计多孔骨支架。首先，基于细分的单个单元对单个孔隙进行建模；然后，利用孔隙之间的布尔运算并集生成组织工程骨支架的整体孔隙模型；最后，通过实体模型与整体孔隙模型之间的布尔运算差来构建包含各种不规则孔隙的骨支架。从扫描电子显微镜图像来看，天然骨中的孔径分布并非随机分布，存在孔径分布梯度。因此，本章还提出了一种基于六面体网格细化的骨支架孔径分布控制方法。基于通过全六面体网格细化可获得六面体单元尺寸分布且孔隙形态和尺寸受六面体单元控制这一事实，能够实现明确的孔径分布。所设计的骨支架可转换为通用的三维文件格式（如STL或STEP），用于快速成型（RP）。最后，采用一种快速成型系统——3D打印（Spectrum Z510）来制造这些骨支架。成功制造的支架验证了本研究中新颖的计算机辅助设计方法。
