Novel methods for socket fabrication and evaluation in transtibial prosthetic applications

Abstract

Despite advancements in technologies and techniques the prosthetics sector remains heavily dependent on experienced clinicians and artisan skills, which are in decline. In turn this is leading to a reduction in quality of care and loss of independence for lower limb amputees. This thesis, therefore, presents a two stranded approach to designing and evaluating a novel method of fabricating transtibial prosthetics by retrofitting existing sockets. This makes use of modern digital technologies to reduce labour requirements, and quantitative measurement tools to assist in clinical decision making. The clinical suitability of smartphone photogrammetry is evaluated as a 3D scanning technique, finding it suitable for positive moulds (volumetric accuracy >98%) whilst unsuitable for sockets (volumetric accuracy ~60%). In addition, a method for assessing dynamic limb-socket coupling performance is identified, using motion analysis, capable of measuring fitment in five degree of freedom whilst walking. The method achieved an error of <0.7mm/degrees, and is compatible with all suspension types. Ultimately a 3D printed lining was produced, using smartphone photogrammetry that could be retrofitted to an obsolete socket, whilst replicating the fit of a comfortable socket. This retrofitted socket was then compared against its traditionally fabricated counterpart, and was scored with a socket comfort score of 8/10 compared to a score of 9/10 for the cloned socket. The performance of the retrofitted socket was reduced with an increased peak to peak pistoning (PD displacement) of 19.5mm, and increased weight of 1,451g compared to 986g. The retrofitting method shows promise and could be the link the sector needs to transition to digital production techniques, offering a host of time, cost, and waste reductions.