Voxel Printing of a Multi-Material 3D Printed Prosthetic Socket Based on FEM Simulations

Prosthetic socket for lower limb amputation needs to be customized based on the residual limb characteristics to satisfy functional and comfort requirements. One of the main causes for ill-fitting socket is the lack of appropriate application of material properties that match the characteristics of the amputee’s biological tissue. Additive manufacturing has the ability to confer inhomogeneous properties to the printed object. This paper presents a digital workflow for the design and fabrication of a prosthetic socket based on the results of numerical simulations and the use of multi-material voxel printing. A voxel model of the socket is generated and the contact pressure between the residual limb and the socket derived from FEA is mapped to the voxels, which were correspondingly assigned a material. This allow to define a material distribution at the voxel level and to generate printing instructions as a stack of bitmap images for voxel printing. The goal is to obtain a socket characterized by a spatial variation of material stiffness, according to the pressure map extracted from simulation, in order to adapt the socket to the patient’s anatomy and, consequently, to reduce contact pressure and discomfort.