Inner design of artificial test bones for biomechanical investigations using topology optimization

Artificial or human test bones are used for the biomechanical testing of implants. Human test bones are rare and not always available. These must, therefore, be substituted with artificial test bones. However, current artificial test bones are only available with specific characteristics (e.g., age groups or disease characteristics). Additionally, their mechanical properties are only comparable to a limited extent to those of a human bone. This paper presents a methodology for designing additively manufactured artificial test bones for biomechanical testing that replicate the mechanical behavior of a human bone. Topology optimization methods are used to generate the artificial test bone's internal structure. The geometric model is based on a computed tomography dataset of a human bone. The input data can be manipulated in advance to reproduce defects or disease patterns. The bone was fixed at the distal diaphysis and loaded with different biomechanical forces for topology optimization. Boundary conditions due to possible additive manufacturing processes were incorporated into the optimization to ensure manufacturability. The optimization result is compared with experimental data from a human bone. A bone-like internal structure and increased compliance of the topology-optimized test bone model compared to the commercial model were observed.