Authors (including presenting author) :
Wong SY (1), Chan KL (1), Ma WL (1)
Affiliation :
(1) Community Rehabilitation Service Support Centre, Queen Elizabeth Hospital
Keyword 1: :
Assistive Technology
Keyword 2: :
Motor Neuron Disease
Keyword 4: :
Reverse Engineering
Introduction :
Motor Neuron Disease (MND) is a progressive neurodegenerative condition characterized by muscle atrophy and a profound decline in motor coordination. For individuals living with MND, a power wheelchair (PWC) is an essential tool for maintaining mobility and facilitating participation in community living. However, the concurrent deterioration of hand function often creates a secondary barrier; standard joystick handles frequently fail to accommodate unique hand deformities or specific patterns of muscle weakness. This mismatch results in poor driving stability and increased physical fatigue, which ultimately limits the patient's independence and safety when navigating their environment.
Objectives :
This case study documents a personalized intervention for a 45-year-old female diagnosed with MND one year prior. The primary objective was to develop a bespoke joystick handle that is tailored specifically to the patient's residual hand anatomy in order to maximize remaining motor function and improve driving stability through a digital manufacturing workflow.
Methodology :
The development process integrated traditional clinical techniques with an advanced digital workflow: Ergonomic Capture: A personalized grip was established using low-temperature thermoplastic molded directly to the patient's hand to capture a functional, neutral posture that minimized joint strain. Digitization and Modeling: This physical mold was digitized via high-precision 3D scanning. The resulting mesh was processed in Autodesk Fusion 360 using reverse engineering techniques to convert the organic shape into a refined CAD model, incorporating an integrated mechanical mounting socket. Fabrication: The device was fabricated using Fused Deposition Modeling (FDM) with PETG (Polyethylene Terephthalate Glycol). PETG was selected for its high impact resistance and mechanical toughness, essential for withstanding the torque of PWC operation. Its chemical resistance allows for regular sanitization without material degradation. Evaluation: The Wheelchair Skills Test (WST) 5.4.3 (Tasks 8-13) was used to assess capacity. User feedback was measured via the device domain of the Chinese version of the Quebec User Evaluation of Satisfaction with Assistive Technology (C-QUEST).
Result & Outcome :
Prior to the intervention, the subject reported significant difficulty with directional accuracy. Baseline assessment using WST Tasks 8-13 (rolling forward/backward and maneuvering) yielded a capacity score of 22.2%. Post-intervention, the subject demonstrated a significant increase in the WST capacity score to 72%, showing vastly improved stability in turning and complex maneuvering. Furthermore, evaluation via the C-QUEST indicated high satisfaction, with an average score of 4.75 out of 5 across dimensions including comfort and effectiveness. This case demonstrates that the synergy of reverse engineering and FDM technology offers a rapid, durable, and highly effective solution for the complex mobility needs of MND patients.
