AccScience Publishing / IJB / Online First / DOI: 10.36922/ijb.3390
RESEARCH ARTICLE

Tuning the mechanical responses of 3D-printed ankle-foot orthoses: A numerical study

Chenxi Peng1,2 Phuong Tran3 Simon Lalor4 Oren Tirosh5 Erich Rutz1,2,6,7,8,9*
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1 Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
2 Murdoch Children’s Research Institute, Parkville, Victoria, Australia
3 RMIT Centre for Additive Manufacturing, School of Engineering, RMIT University, Melbourne, Victoria, Australia
4 Orthotic and Prosthetic Department, The Royal Children’s Hospital Melbourne, Parkville, Victoria, Australia
5 School of Health and Biomedical Sciences, STEM College, RMIT University, Bundoora, Victoria, Australia
6 Bob Dickens Chair Paediatric Orthopaedic Surgery, The University of Melbourne, Parkville, Victoria, Australia
7 Orthopaedics Department, The Royal Children’s Hospital Melbourne, Parkville, Victoria, Australia
8 The Hugh Williamson Gait Analysis Laboratory, The Royal Children’s Hospital Melbourne, Parkville, Victoria, Australia
9 Medical Faculty, The University of Basel, Basel, Switzerland
IJB 2024, 10(3), 3390 https://doi.org/10.36922/ijb.3390
Submitted: 9 April 2024 | Accepted: 8 May 2024 | Published: 7 June 2024
© 2024 by the 2024 Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
Abstract

Ankle-foot orthoses (AFOs) are frequently prescribed for children with cerebral palsy (CP) to correct specific features of abnormal gait. However, traditional AFO manufacturing and design involve labor-intensive processes and rely on subjective evaluations of clinicians. Recent advances in three-dimensional (3D) printing allow the rapid prototyping of AFOs, but the expanded design options complicate decision-making. This study aims to evaluate how AFO design affects the mechanical responses of 3D-printed AFOs. The lower limb geometry is established by a 3D-scanning system, and a prototypical AFO is designed, 3D printed, and tested under compression. A parametric study on the effect of base materials, thickness, and trimline location is conducted based on a validated numerical model. The results reveal that AFOs exhibit distinct behaviors under plantarflexion and dorsiflexion motions, with AFO stiffness correlating to thickness through a power function. AFO stiffness is more sensitive to posterior trim depth than inferior, while both trim depths significantly influence stress concentration around the ankle region. This investigation demonstrates the potential of combining 3D printing and computational modeling to improve the design and fabrication process of AFOs, providing insights into the development and customization of 3D-printed AFOs.

Keywords
Cerebral Palsy
Ankle-foot orthoses
3D printing
Computational modeling
Stiffness
Dorsiflexion
Plantarflexion
Funding
None.
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Conflict of interest
The authors declare no conflicts of interest.
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International Journal of Bioprinting, Electronic ISSN: 2424-8002 Print ISSN: 2424-7723, Published by AccScience Publishing