A Structured Rehabilitation Protocol for Improved Multifunctional Prosthetic Control: A Case Study

Summary

As prosthetic development moves towards the goal of natural control, harnessing amputees’ inherent ability to learn new motor skills may enable proficiency. This manuscript describes a structured rehabilitation protocol, which includes imitation, repetition, and reinforcement learning strategies, for improved multifunctional prosthetic control.

Abstract

Advances in robotic systems have resulted in prostheses for the upper limb that can produce multifunctional movements. However, these sophisticated systems require upper limb amputees to learn complex control schemes. Humans have the ability to learn new movements through imitation and other learning strategies. This protocol describes a structured rehabilitation method, which includes imitation, repetition, and reinforcement learning, and aims to assess if this method can improve multifunctional prosthetic control. A left below elbow amputee, with 4 years of experience in prosthetic use, took part in this case study. The prosthesis used was a Michelangelo hand with wrist rotation, and the added features of wrist flexion and extension, which allowed more combinations of hand movements. The participant’s Southampton Hand Assessment Procedure score improved from 58 to 71 following structured training. This suggests that a structured training protocol of imitation, repetition and reinforcement may have a role in learning to control a new prosthetic hand. A larger clinical study is however required to support these findings.

Introduction

Replacing hand function in amputees is a difficult endeavor. Coordinating highly skilled hand movements is not an innate ability, and takes humans years of learning to develop.^1–5 After the traumatic loss of a hand, replicating this capability by prosthetic means is not a trivial task and may require a period of sustained learning.

Prosthetic design and interfacing methods for their control are subject to rapid technological innovations, with the goal of multifunctional control in a natural manner.⁶ The complexity of these control systems increases substantially to provide more functions for amputees. To ensure a....

Protocol

This study was carried out in accordance with the Declaration of Helsinki, as approved by the local research ethics committee. The study was explained in full detail to the participant prior to commencement, allowing the participant the time to weigh up the decision to voluntarily take part in the study and confirm his participation by informed, written consent.

Note: One man, aged 27 years, took part in the study. The participant had normal vision, was a left below-elbow amputee, and was an experienced user (4 years total prosthesis use). Prior to commencing this study the prosthesis he used on a daily basis was a 4 channel myoelectric pro....

Results

The baseline SHAP performance of the participant with his daily prosthesis was 81 when measured by the clinical staff 8 months prior to testing. A SHAP score of 100 represents able-bodied hand function.²⁴ The participant scored an overall SHAP score of 58 during the naïve session with the more advanced prosthesis control system. However, 3 months later and with no further interaction with the new system, aside from the structured training, the participant achieved a SHAP score of 71 with the same advanced syst.......

Discussion

Our findings suggest for the participant in this study that structured training helped improve control of a multifunctional prosthetic hand during one single session. The structured program used here was a combination of imitation, repetition and reinforcement of hand movements that the participant was not able to complete with his traditional prosthetic hand.

Although the participant scored higher with his traditional prosthesis in the SHAP test, it is worth noting that he typically wore that.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Michelangelo Hand	Otto Bock Healthcare Products GmbH, A	8E500=L-M
AxonRotation	Otto Bock Healthcare Products GmbH, A	9S503
Wrist Flexor	Otto Bock Healthcare Products GmbH, A		prototype unit
AxonMaster	Otto Bock Healthcare Products GmbH, A	13E500
Electrode	Otto Bock Healthcare Products GmbH, A	13E200=50AC
ScissorFenceElectrodeCarrier	Otto Bock Healthcare Products GmbH, A		prototype unit
Acquisition Software	Otto Bock Healthcare Products GmbH, A		prototype unit
Carbon shaft	Otto Bock Healthcare Products GmbH, A		prototype unit