A Visual Feedback Tool for Quantitative Pressure Monitoring in Lower-Limb Prosthetic Sockets

Shruti Turner,Alison H Mcgregor,Akhil Patel,Shivali Jain,Matthew O Hopkins

doi:10.3390/prosthesis3040035

Abstract

Obtaining a good socket fit is an iterative process dependent on the skill and experience of the prosthetist creating it and requires individualisation based on the size and shape. There is no standard measurement system used to aid prosthetic socket creation despite the severe impacts on physical health and quality of life if one is ill fitting. Pressure sensors embedded in a prosthetic socket were used to collect data at the socket–residuum interface. To choose an interpolation method, the sensor array was simplified to a 2D grid with a border for extrapolation and tested using previously collected walking test pressure data. Four multivariable interpolation methods were evaluated to create a colour map of the pressure data. Radial basis function interpolation was chosen, as it produced a clear image with a graduated interpolation between data points, and was used to create a colour map across the surface of a 3D prosthetic socket model. For the model to be accessible to clinical audiences, a desktop application was created using PyQt to view the model. The application allowed for connection to the sensors via Bluetooth, with the pressure data updating on the 3D model in real time. Clinician feedback on the application showed the potential for a clinical product; however, further development informed by feedback from rehabilitation clinicians and prosthesis users is required.

Highlights

The prosthetic socket is the point of load transfer between the body and the prosthesis and is a complex interface [1,2]
For the sensor hardware to be useful in a clinical environment, the information relevant to clinicians and people with amputation(s) must be displayed in an easy-to-understand manner, requiring little interpretation or training and no additional technical knowledge
Visual feedback has been shown to have a positive effect on rehabilitation when it complements traditional methods

Summary

Introduction

The prosthetic socket is the point of load transfer between the body and the prosthesis and is a complex interface [1,2]. The socket is not an ideal environment for the residual limb due to the load distribution over anatomy and tissues that have not evolved for this purpose. The bony prominences and skin on the residual limb are subjected to a hot, moist environment with greater loading conditions compared with pre-amputation [5]. The residual limb is highly susceptible to complications— including skin tissue breakdown—that can lead to deep tissue injury and the formation of pressure ulcers [6,7,8,9]. A critical factor in the development of pressure sores is the presence of shear in the soft tissues, often present due to movement of the residual limb [10]. Pressure sores negatively affect the quality of life of 62% of prosthesis users, frequently prohibiting prosthetic use [6,8,11,12]

Methods

Findings

Discussion

Conclusion