Replicating and redesigning ankle-foot orthoses with 3D printing for children with Charcot-Marie-Tooth disease

Elizabeth A Wojciechowski; Tegan L Cheng; Sean M Hogan; Anita J Mudge; Daniel Balassone; Manoj P Menezes; David G Little; Leanne N Dwan; Joshua Burns

doi:10.1016/j.gaitpost.2022.05.006

Replicating and redesigning ankle-foot orthoses with 3D printing for children with Charcot-Marie-Tooth disease

Gait Posture. 2022 Jul:96:73-80. doi: 10.1016/j.gaitpost.2022.05.006. Epub 2022 May 11.

Authors

Elizabeth A Wojciechowski¹, Tegan L Cheng², Sean M Hogan³, Anita J Mudge³, Daniel Balassone³, Manoj P Menezes², David G Little², Leanne N Dwan², Joshua Burns²

Affiliations

¹ University of Sydney School of Health Sciences, Faculty of Medicine and Health & Children's Hospital at Westmead, Sydney, Australia; The Children's Hospital at Westmead, Westmead, Australia. Electronic address: elizabeth.wojciechowski@sydney.edu.au.
² University of Sydney School of Health Sciences, Faculty of Medicine and Health & Children's Hospital at Westmead, Sydney, Australia; The Children's Hospital at Westmead, Westmead, Australia.
³ The Children's Hospital at Westmead, Westmead, Australia.

PMID: 35597049
DOI: 10.1016/j.gaitpost.2022.05.006

Abstract

Background: Children with the most common inherited neuropathy, Charcot-Marie-Tooth disease (CMT), are often prescribed ankle-foot orthoses (AFOs) to improve walking ability and prevent falls by reducing foot drop, postural instability, and other gait impairments. These externally worn assistive devices are traditionally custom-made using thermoplastic vacuum forming. This labour-intensive manufacturing process often results in AFOs which are cumbersome due to limited design options, and are associated with low acceptability, discomfort, and suboptimal impact on gait. The aim of this study was to determine how 3D printing can be used to replicate and redesign AFOs in children with CMT.

Methods: Traditional AFOs, 3D printed replica AFOs (same design as traditional AFOs), 3D printed redesigned AFOs and a shoes only control condition were compared in 12 children with CMT. 3D printed AFOs were manufactured using material extrusion in Nylon-12. 3D gait analysis (temporal-spatial, kinematic, kinetic), in-shoe pedobarography and self-reported satisfaction were used to compare conditions. The primary kinematic and kinetic outcome measures were maximum ankle dorsiflexion in swing and maximum ankle dorsiflexor moment in loading response, to capture foot drop and an absent of heel rocker.

Results: The 3D printed replica AFOs were comparable to traditional AFOs for all outcomes. The 3D printed replica AFOs improved foot position at initial contact and during loading response and significantly reduced pressure beneath the whole foot, rearfoot and forefoot compared to the shoes only. The 3D printed redesigned AFOs produced a device that was significantly lighter (mean -35.2, SD 13.3%), and normalised maximum ankle dorsiflexor moment in loading response compared to shoes only and traditional AFOs.

Significance: 3D printing can be used to replicate traditional handmade AFOs and to redesign AFOs to produce a lighter device with improved biomechanics by incorporating novel design features.

Keywords: Additive manufacturing; Assistive devices; Gait analysis, 3D printing; Inherited neuropathy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Ankle
Biomechanical Phenomena
Charcot-Marie-Tooth Disease*
Child
Foot Orthoses*
Gait / physiology
Humans
Peroneal Neuropathies*
Printing, Three-Dimensional