Design and Finite Element Analysis of a Custom Wrist Orthosis for 3D Printing Containing Ventilation Areas and Wrist Protection Zones Achieved by Topological Optimization

Currently, there are many different types of orthoses designed to be made using additive manufacturing methods (3D printing), in which numerous pattern structure are used. These structures are mainly intended to reduce the weight of the orthosis and consequently reduce the material needed for printing. Unfortunately, the arrangement of these structures is often random and does not result from strength analyses. This work presents the design of a customized wrist orthosis containing open areas whose shape and location were determined based on the results of topological optimization. For this purpose, a modified 3D scan of the upper limb was used, based on which a 3D model of a typical (full) wrist orthosis was created. This model was used to perform topological optimization for 4 different load cases corresponding to movements performed in the wrist joints. The results obtained in this way were used to design ventilation areas in the orthosis model, taking into account protective areas necessary from medical point of view. Then, 3D models of the full orthosis structure and the orthosis after optimization were subjected to Finite Element Analysis (FEA). The results of FEA provided information about the necessary corrective changes were made to the geometry of the orthosis in order to improve its strength – e.g. widening the material strip in critical areas. The final 3D model of the wrist brace obtained in this way was verified in terms of meeting the adopted design assumptions and strength requirements.