ABSTRACT: In this study, an artificial neural network (ANN) was deployed as a tool to determine the internal loads between the residual limb and prosthetic socket for below-knee amputees. This was achieved by using simulated load data to validate the ANN and captured clinical load data to predict the internal loads at the residual limb–socket interface. Load/pressure was applied to 16 regions of the socket, using loading pads in conjunction with a load applicator, and surface strains were collected using 15 strain gauge rosettes. A super-position program was utilised to generate training and testing patterns from the original load/strain data collected. Using this data, a back-propagation ANN, developed at the University of the West of England, was trained. The input to the trained network was the surface strains and the output the internal loads/pressure. The system was validated and the mean square error (MSE) of the system was found to be 8.8% for 1000 training patterns and 8.9% for 50 testing patterns, which was deemed an acceptable error. Finally, the validated system was used to predict pressure-sensitive/-tolerant regions at the limb–socket interface with great success.
Strain 01/2006; 42(1):3 - 10. · 1.10 Impact Factor
ABSTRACT: It is recognized that the assessment of prosthetic socket fit is based largely on the subjective clinical judgement of the prosthetist. This study assesses a novel technique, photoelasticity, for use as a tool for the qualitative and quantitative assessment of socket fit. Photoelasticity is a visual technique that produces contours of principal stress or strain differences. The colour and/or distance between the contours can be qualitatively or quantitatively assessed, using a polariscope, to give a full-field analysis of the stresses on the sockets's surface. This paper presents qualitative photoelastic socket surface contour data gathered during several prosthesis fitting sessions for two male trans-tibial amputees. Results are compared with the actual known contact regions at the stump/socket interface to determine if a relationship exists. This comparison of results has then been used to conclude the suitability of photoelasticity as a tool for the assessment of socket fit and recommendations are made as to the future developments of the technique. A direct relationship between the stump/socket contact regions and the qualitative photoelastic contours was demonstrated. Given further development this photoelastic technique may therefore be suitable for qualitative analysis of the interactions between the stump and prosthetic socket.
Prosthetics and Orthotics International 01/2006; 29(3):291-302. · 0.95 Impact Factor
ABSTRACT: So far the study of interfacial pressures between residual limb
and the prosthetic socket has not led to the design of any useful tool
that can assist the prosthetist to fit a prosthesis. Researchers at the
UWE Bristol have found a novel methodology that can revolutionise this
process. It is based on the combined application of a hybrid numerical
method and experimental finite element analysis for stress analysis.
This paper represents part of the development process of this tool and
discusses the step forward from a two-dimensional analysis, discussed
previously (2000), into a 3D symmetrical shell analysis which is
intended to simulate a structured and ideal socket. The authors feel
this is a logical step, which is necessary for understanding the
relationship between surface stress/strain, and internal load, which
causes those surface stresses. This paper emphasises the significance of
this statement because it requires no knowledge of tissue properties
Neural Networks, 2001. Proceedings. IJCNN '01. International Joint Conference on; 02/2001
ABSTRACT: A revolution in trans-tibial prosthetic design began at the end of World War II with the development of new materials and a dramatic improvement in the understanding of biomechanics. Early research was based mainly on the improvement of existing prosthetic design practice. Today, research has been focused on providing a better understanding of stump/socket interface biomechanics and improving socket fit by attempting to quantify the normal/direct stresses at the interface. The purpose of this review paper is to question whether research and prosthetic education/training to date has significantly improved our understanding of what makes a good socket. Although there is no doubt that advances in socket fitting techniques have been made what is not clear is the actual extent to which these advances have improved the quality of sockets fitted. It is suggested that a new approach is needed which can overcome some of the inherent problems of designing and manufacturing a comfortable high quality socket. It is also suggested that current research and education/training in the fields of pressure/interfacial interaction measurement and Finite Element Analysis techniques have limited potential to address many of these problems. There is also little evidence that current computer aided design systems offer any significant advantages over more conventional techniques.
Prosthetics and Orthotics International 09/2000; 24(2):97-107. · 0.95 Impact Factor