Design and 3D printing of a customised wrist-hand orthosis

This study outlines a comprehensive methodology for the design and 3D printing of personalized wrist-hand orthoses. The novelty of this work consists in using a comprehensive methodology that combines 3D scanning, CAD modelling, FEM simulation, and FDM 3D printing to create a personalized wrist-hand orthosis (RO) that fits the patient's hand geometry and biomechanical requirements with an increased breathability and ventilation. It starts with a precise 3D scanning process capturing complex hand details, followed by an accurate post-processing for data refinement. Subsequently, the imported mesh model is employed in CAD software to facilitate complex modelling of the orthosis. Using a reverse engineering approach, a 3D model of the orthosis is generated, accommodating its intricate and unique shape. Fused Deposition Modeling (FDM) technology is utilized to ensure cost-effectiveness, employing PLA material, known for its biomechanical attributes. Mechanical anisotropy inherent to 3D-printed objects due to layering is assessed through tensile tests, which are conducted with specimens printed at various orientations (0 degrees, 45 degrees/- 45 degrees, 90 degrees). Following established standards, mechanical properties are derived and added into a numerical simulation employing ANSYS Workbench software. This simulation aims to optimize the orthosis's design, considering approximate wrist-level loading conditions. The resultant structure is then realized through FDM 3D printing technology. The orthosis's mechanical performance is evaluated via a 3-point bending test, consistent with prior literature standards, revealing high rigidity and load-bearing capabilities compared to existing orthotic devices. In the pursuit of ease of use, assembly and disassembly options are explored, culminating in a two-part orthosis design with a user-friendly Snap-Fit mechanism for simple use, durability, and resistance. Additionally, comfort and fitting tests validate the practicality of the design, while patients have the freedom to choose their preferred colour, enhancing the overall aesthetics and user satisfaction.