Case study: Hybrid model for the customized wrist orthosis using 3D printing

Abstract

The currently used plaster cast for wrist orthotic treatment is relatively heavy, non-removable, and unventilated. Because of this, wearing this cast can generate problems including a variety of skin diseases, pilosis, and joint and ligament injuries. This case study describes a hybrid manufacturing methodology that utilizes three-dimensional printing (3D printing) and injection molding technology to create a wrist orthosis that solves the problems of the plaster casts. Compared with the previously presented wrist orthosis using 3D printing and three-dimensional scanning (3D scanning) technology, the proposed hybrid model significantly reduces the manufacturing time and cost. The core concept of the hybrid model is to separate the plastic cast into two parts: an inner structure produced by 3D printing that surrounds the skin and an outer cover that is fastened to the inner structure that protects the injured part from external forces. The outer cover is produced in advance using an injection molding method with three sizes based on the sizes of the wrist. From the result of wearing the prototype, it was confirmed that the new wrist orthosis has proper strength, good ventilation, and light weight. The time cost for manufacturing also was estimated as 1/3 of that of other methods. We anticipate that the hybrid method for customized 3D printed plastic orthosis can become a balanced solution that can be applied in the current additive manufacturing field in terms of manufacturing time and cost.