Trans-radial Socket Coupling Problems And Solutions

Prince, Michael

Abstract

There has been relatively little research into the assessment of socket fit in upper-limb
prosthetics, in comparison to lower-limb prosthetics. Whilst this reflects the smaller
population of potential users, the global need for devices is nonetheless substantial. The
measurement of socket fit was explored through a literature review and suitable
quantifiable parameters identified, with a focus on the relative movement between socket
and residuum, governed by their mechanical coupling. To clarify the use of these variables
in socket evaluation, a good ‘fit’ was defined as the optimal balance between the coupling
of the socket, and a measure of tissue health. A novel system was then developed for the
quantification of coupling, based around the use of a 3D scanner. This used spherical
targets to define Templates for different objects in a scan, and was shown to be capable of
identifying and measuring the relative pose of those objects, specifically a socket relative
to an arm. This approach was used to demonstrate the measurement of coupling with an
anatomically intact subject. Evaluation of the apparatus required a test socket, and an
analysis of user needs was performed, resulting in the choice of an open-frame design. A
novel tool was then created to aid the design of those components (pads) interfacing
directly with the residuum. It was demonstrated that the tool can be used to apply a known
pressure distribution to a relatively large area of tissue, before capturing the shape of the
resultant tissue displacement. The specific importance of socket coupling for users of myo-
electric upper-limb prostheses was also addressed, as artefactual signals can be generated
when socket perturbations cause electrodes to lift or slip relative to the residuum. Further
novel measurement techniques were introduced to quantify this movement envelope, with
the results informing the development of a new electrode housing through several cycles
of prototyping. This device, which mechanically partially de-couples the electrode from the
socket within an appropriate working volume, was used to demonstrate reductions in
signal artefacts in comparison with a standard electrode housing.

Citation

Prince, M. (2024). Trans-radial Socket Coupling Problems And Solutions. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Apr 17, 2024
• Publicly Available Date: Apr 26, 2026
• Award Date: Apr 25, 2024