Biomedical Engineering Division, Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran.
Biomedical Engineering Division, Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran.
J Mech Behav Biomed Mater. 2021 Aug;120:104595. doi: 10.1016/j.jmbbm.2021.104595. Epub 2021 May 26.
Application of porous cells in orthopedic implants makes it possible to better approximation of elastic property of human bones. Although the mechanical and biological properties of orthopedic porous implants are studied in many researches, the interaction between different porous unit cells from geometrical compatibility and also, considering manufacturing conditions for the ultimate goal of bone ingrowth is not thoroughly investigated. In this study, a kelvin cell is designed with 530 to 810 μm pore sizes, which is the appropriate range for bone ingrowth. Due to anatomical position of implants in the human body and the limited range of the elastic modulus of kelvin cell with different geometrical parameters, this unit cell is combined with other cells to extend the range of its elastic modulus. After selecting the appropriate combination of cells to achieve desired properties, they are fabricated with Stainless Steel 316 L using radially gradient porosity in the range of 64% to 80%, and then finite element method (FEM) is performed to evaluate the elastic modulus, stress distribution, and strain energy of the proposed structures. Gradient and uniform structures are fabricated using selective laser melting (SLM) to validate FEM results. The simulation and experimental results are close to each other with an average error of about 4.5%. The elastic modulus derived from FEM for the designed gradient structures are in the range of 7.48 to 10.49 GPa, which can be modified, and present mechanical properties close to trabecular or compact bone based on the position and conditions of the bone defect.
多孔细胞在骨科植入物中的应用使得更好地接近人体骨骼的弹性特性成为可能。尽管许多研究都研究了骨科多孔植入物的机械和生物学特性，但不同多孔单元之间的相互作用，从几何兼容性考虑，以及考虑到最终目的是骨长入的制造条件，尚未得到彻底研究。在这项研究中，设计了一种 Kelvin 单元，其孔径为 530 至 810μm，这是适合骨长入的范围。由于植入物在人体中的解剖位置以及具有不同几何参数的 Kelvin 单元的弹性模量的有限范围，因此该单元与其他单元结合使用，以扩展其弹性模量范围。选择合适的单元组合以达到所需的性能后，使用不锈钢 316L 制造，其径向梯度孔隙率在 64%至 80%之间，然后使用有限元方法 (FEM) 评估所提出结构的弹性模量、应力分布和应变能。使用选择性激光熔化 (SLM) 制造梯度和均匀结构，以验证 FEM 结果。模拟和实验结果非常接近，平均误差约为 4.5%。通过 FEM 得出的设计梯度结构的弹性模量范围为 7.48 至 10.49GPa，可进行修改，并根据骨缺损的位置和条件呈现出接近小梁骨或密质骨的机械性能。
