Validation of Ankle Foot Orthosis Designs Using Finite Element Method

Abstract

Neuromuscular disorders such as multiple sclerosis, stroke, and cerebral palsy are becoming more common than they were in earlier decades. Drop foot is one of the lower limb impairments caused by these disorders. Weakened dorsiflexor muscles are the main cause of drop foot. It could be treated using traditional methods, but not in all cases. Ankle foot orthoses (AFOs) are types of lower limb orthoses which support ankle plantarflexor and dorsiflexor muscles and considered an effective solution for those disorders. AFOs are external supporting devices with a L form, originally made of plastic and leather materials. There is a need for revolutionary materials and designs to achieve optimal function and patient comfort without fracture of the AFO. The simulation study allows researchers to assess either materials or designs before human trials as it limits injuries and bone fracture. In this study, three distinct AFO designs are simulated using finite element analysis and various materials to ensure functionality and material resistivity before being used in clinical trials on patients. The proposed materials used in this study are polypropylene (PP), carbon fiber reinforced polymer (CFRP), and multi-walled carbon nanotubes mixed with resin (MWCNTs/Resin). All designs are evaluated utilizing equivalent stress, total deformation, and computational time with the material types. Design 1 resulted in minimum stress affected by the applied force. Design 2 MWCNTs/Resin could resist forces more than the CFRP. While Design 3 had the maximum deformation results. Design 1 with MWCNts/resin material resulted in an acceptable result compared to other types.