Exploring Orthosis Designs for 3D Printing Applying the Finite Element Approach: Study of Different Materials and Loading Conditions

Abstract

Three-dimensional (3D) printing, especially using fused deposition modeling, is becoming more and more popular in the medical sector because of its exceptional advantages. While it has been used for prototyping, 3D printing has not yet been completely explored to produce a functional product. The key causes are the abundance of 3D printing materials and the lack of a comprehensive study outlining the design process. Consequently, this paper describes a reverse engineering (RE) design approach based on data acquisition utilizing laser scanning and splint design from the acquired point cloud data. This study also focuses on the evaluation of various wrist orthosis/splint designs and materials using finite element (FE) analysis in order to improve upon the conventional approach. Sixty FE analysis simulations are undertaken in flexion–extension and radial–ulnar wrist movements to investigate the displacements and the stresses. The splint is then fabricated utilizing the material and thickness that have been specified by FE analysis. The major goals of this study are to examine the RE design methodology, explore various materials, and assess the viability of 3D printing. The polylactic acid (PLA) hand splint has proven to be the sturdiest in terms of average displacements when compared to the other materials, followed by polyethylene terephthalate glycol (PETG), acrylonitrile butadiene styrene (ABS), polypropylene, and thermoplastic polyurethanes. According to simulation data, the PLA splint has 38.6%, 38.8%, 38.5%, and 38.7% less displacement in the major loading direction in flexion, extension, radial, and ulnar, respectively, than the ABS splint. Moreover, the PLA-based hand splint has a peak stress value below the yield strength of PLA, rendering it reliable for patients to wear. Also, it turns out that PETG and ABS behave rather similarly. Furthermore, it has been shown that a balanced approach can reduce material use and building time. For instance, employing PLA and a thickness of 2 mm results in reduced material costs without compromising the effectiveness of the splint. As a result, choosing the right material and splint thickness can help the 3D-printed hand splint perform better.