A reasonable approach to determine structural dimension of FDM fabricated orthopedic orthosis using finite element simulation and simple additive weighting method

Introducing Additive Manufacturing (AM) techniques for orthopedic orthosis fabrication is a significant help in treating of patients with fractured wrists. In particular, customized orthosis fabricated by Fused Deposition Modeling (FDM) can provide best patient comfort with reduced incidence of various complications due to air permeability. The research objective of this paper is to determine reasonable structural dimension for reducing unnecessary material consumption while ensuring strength and safety when fabricating the customized orthopedic orthosis by the FDM technique. This paper presents a reasonable approach to determine structural dimension of the FDM fabricated orthopedic orthosis using Uniform Design (UD), finite element simulation, Simple Additive Weighting (SAW) method, multiple regression analysis, and grid search optimization method. Three-dimensional (3D) models of wrist were reconstructed from computer tomography image data for wrist fracture sites. Nine Computer-Aided Design (CAD) 3D models of the wrist orthosis with different shell thickness, lattice thickness and number of vents were designed using the UD method. The stress analyzes with load conditions in different directions were carried out using the finite element simulation and overall performance scores (simple weighted sums) were calculated using the SAW method at each experimental trial. The reasonable structural dimension of the wrist orthosis was determined using multiple regression model and grid search optimization method. The reasonable structural dimension was shell thickness of 2.2 mm, lattice thickness of 6.4 mm, and number of ventilation holes of 15. The fabricated orthosis with the reasonable structural dimension may improve the treatment effect, satisfaction and comfort for patients with fractured wrists. The proposed approach could be actively applied to optimize not only the structural dimension of FDM fabricated orthosis but also FDM process parameters.