Performance evaluation and analysis of different materials used for orthotic devices to support an injured leg

Abstract

Injuries occurring worldwide, including in Rwanda, are often the result of incidents in various workplace sectors, with transportation being the leading cause. These injuries frequently lead to prolonged suffering during medical treatment due to the lack of appropriate medical support devices. This study aims to develop and evaluate the performance of a realistic three-dimensional Finite Element (FE) model of a foot-ankle orthotic device made from various materials. The footankle model was designed and analyzed using SolidWorks, and the obtained results were validated using ABAQUS software. The validation process incorporated a realistic patient model, assuming a standard person weighing 70 kg and measuring 176 cm in height. Three different materials, Polypropylene (PP), Carbon Fiber Reinforced Polymer (CFRP) and Poly Lactic Acid (PLA) were evaluated to determine the most suitable material for the orthotic device. The FE model was subjected to rigorous mesh reliability verification in each software. Von Mises stress and deformation displacement of the foot-ankle orthotic device were studied separately for each material. The simulation results indicate that CFRP demonstrates superior resistance to external forces under typical patient usage conditions, followed by PP. CFRP also exhibited the least deflection, measuring 7.603 mm in ABAQUS and 8.579 mm in SolidWorks. The corresponding Von Mises stresses of 1.981e+01 MPa in ABAQUS and 1.796e+01 MPa in SolidWorks. The contact area during the analysis was found to be 483.55 mm2 for the normal foot-ankle orthotic device. PLA showed the least resistance under the same conditions, as also indicated by previous experiences. Thus, CFRP emerges as the preferred material for foot-ankle orthotic device design due to its superior stability under contact pressure and lower von Mises stress compared to other materials. However, it is important to note that no formal analytical validation has been conducted for the preclinical analysis of the foot-ankle orthotic device in line with 3D simulation. The AFOs (Ankle-Foot Orthoses) designed and evaluated in this study are recommended for future implementation and use.