Three-dimensional-printed femoral diaphysis for biomechanical testing-Optimization and validation

Polylactic acid (PLA) models of normal human femoral diaphyses were designed using three-dimensional (3D) printing technology to create inexpensive, accessible, and reproducible specimens for flexural biomechanical studies. These models were subjected to three-point bending and their response to loading was characterized. The anisotropic mechanical behavior of the 3D-printed femurs and the influence of printing orientations, infill density, wall layers, resolution, and other printing parameters were explored to develop a design space. The objective of the design space was set to emulate the flexural biomechanical response of the normal human femur bones. Results show the 3D-printed PLA diaphyseal femurs with 5% infill density, two-four wall layers, and a resolution of 200 µm resulted in a flexural strength of 184.8 ± 8.18 MPa. Models with 20% infill density and six wall layers resulted in a flexural modulus of 18.54 ± 0.543 GPa. These results emulate the biomechanical response of the normal human femur, as determined by historical target values derived from prior cadaveric and 3D printing data. With further research, inclusive of modeling the proximal and distal femur and more comprehensive biomechanical testing, 3D-printed femurs may ultimately serve as a cheap, accessible biomechanical resource for surgeons and researchers.