Numerical and Experimental Study of a Lattice Structure for Orthopedic Applications

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 σf = 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 σf = 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.

Extension of the Voronoi Diagram Algorithm to Orthotropic Space for Material Structural Design

“…Each basic cell possesses some mechanical properties. Previously, we considered them as anisotropic media [ 32 , 33 ]. Assuming that the origin of anisotropy is provided by the microarchitecture, the parameter vector p was introduced.…”

Method of computational design for additive manufacturing of hip endoprosthesis based on basic‐cell concept

“…A commonly used method for designing AM products is based on topology optimization of their lattice structure. The optimal choice of the lattice‐cell size and shape was recently discussed in References 18–24. Changes in the shape and size of pores in a lattice cause variation in mechanical properties.…”

Experimental Evaluation of the Effects of Discrete-Grading-Induced Discontinuities on the Material Properties of Functionally Graded Ti-6Al-4V Lattices

“…Additively manufactured patient-specific medical devices have the benefit of matching individual patient's bone anatomy due to the high customizability of AM process [5][6][7]. Additionally, unlike subtractive manufacturing, where most products have solid internals [8], additive manufacturing can accommodate intricate micro-architected internal geometry [9]. This feature is particularly desirable for designing and manufacturing human bone implants because of the tunable material properties of the implants, made possible by functionally graded lattices (FGLs) [10].…”