Ankle-Foot Orthosis (AFO) Design

Abstract

The team was assigned to work with Anderson Orthopedics (AO), a private company specializing in the ability to provide patients with a customized ankle-foot orthosis (AFO). The main objective of the project was to optimize the posterior strut geometry of the AFO for individuals suffering from dorsiflexor and plantarflexor weaknesses, and be able to 3D print the brace in order to receive patient feedback.After identifying the needs and constraints of the project, the team was able to begin concept development for the AFO and brainstormed 17 preliminary concepts, which were narrowed down to four concepts using qualitative screening analyses. The top four designs chosen were: the Basic (#1), Wishbone (#5), Posterior Lattice (#10), and Layered Strut (#11) concepts. Finally, a preliminary qualitative FEA scoring analyses was performed in order to choose the final concept design to further optimize based on the performances under the constrained settings of the gait cycle, on a modifying software SolidWorks®. As a result, the Basic concept was selected.In order to optimize the design of the Basic concept, the team considered three main variables: material selection, inclination angle, and material thickness. The final model chosen to 3D print was made out of PC-ISO and an inclination angle of 90°, which we name the Basic(PC-ISO, 90°). Using this model, further optimization and customization of the brace was performed, which resulted inthe final model: BIA.The BIA was 3D printed using PC-ISO at an inclination angle of 90°, sole thickness of 3 mm, and varying posterior strut thickness from 4-7 mm,which resulted ina spring-back force of approximately 168 N, and an estimated increase in energy return of 38%. The total cost of manufacturing the BIA at North Forge was roughly $264.The last phase of the project consisted of3D printing the Basic (PC-ISO, 90°) model and presenting our final model, BIA, to the client and patient for feedback. After receiving feedback from both the client and patient, recommendations for any future development in the projectwere made.