Numerical and Experimental Study of a Lattice Structure for Orthopedic Applications

Nikita Kharin; Pavel Bolshakov; Alex G Kuchumov

doi:10.3390/ma16020744

Numerical and Experimental Study of a Lattice Structure for Orthopedic Applications

Materials (Basel). 2023 Jan 12;16(2):744. doi: 10.3390/ma16020744.

Authors

Nikita Kharin^{1

2}, Pavel Bolshakov³, Alex G Kuchumov^{4

5}

Affiliations

¹ Institute of Mathematics and Mechanics, Kazan Federal University, 420008 Kazan, Russia.
² Institute of Engineering, Kazan Federal University, 420008 Kazan, Russia.
³ Department Machines Science and Engineering Graphics, Tupolev Kazan National Research Technical University, 420111 Kazan, Russia.
⁴ Department of Computational Mathematics, Mechanics and Biomechanics, Perm National Research Polytechnic University, 614990 Perm, Russia.
⁵ Laboratory of Mechanics of Biocompatible Materials and Devices, Perm National Research Polytechnic University, 614990 Perm, Russia.

Abstract

Prosthetic reconstructions provide anatomical reconstruction to replace bones and joints. However, these operations have a high number of short- and long-term complications. One of the main problems in surgery is that the implant remains in the body after the operation. The solution to this problem is to use biomaterial for the implant, but biomaterial does not have the required strength characteristics. The implant must also have a mesh-like structure so that the bone can grow into the implant. The additive manufacturing process is ideal for the production of such a structure. The study deals with the correlation between different prosthetic structures, namely, the relationship between geometry, mechanical properties and biological additivity. The main challenge is to design an endoprosthesis that will mimic the geometric structure of bone and also meet the conditions of strength, hardness and stiffness. In order to match the above factors, it is necessary to develop appropriate algorithms. The main objective of this study is to augment the algorithm to ensure minimum structural weight without changing the strength characteristics of the lattice endoprosthesis of long bones. The iterative augmentation process of the algorithm was implemented by removing low-loaded ribs. A low-loaded rib is a rib with a maximum stress that is less than the threshold stress. Values within the range (10, 13, 15, 16, 17, 18, 19 and 20 MPa) were taken as the threshold stress. The supplement to the algorithm was applied to the initial structure and the designed structure at threshold stresses σ_f = 10, 13, 15, 16, 17, 18, 19 and 20 MPa. A Pareto diagram for maximum stress and the number of ribs is plotted for all cases of the design: original, engineered and lightened structures. The most optimal was the designed "lightweight" structure under the condition σ_f = 17 MPa. The maximum stress was 147.48 MPa, and the number of ribs was 741. Specimens were manufactured using additive manufacturing and then tested for four-point bending.

Keywords: additive manufacturing; bone endoprosthesis; lattice structure; porous constructions; structural design.

Grants and funding

075-15-2021-578/Megagrants