Enabling a paradigm shift in prosthesis design through measurement and modelling of functional properties
Although new technologies are continually being introduced, real improvements in the performance of lower-limb prostheses have often been slow to appear. We believe that this is a direct result of the research methodologies usually adopted. With a few notable exceptions, most attempts to assess lower-limb prostheses have been based on empirical studies that focus only on the quality of the amputee gait, but not the mechanical properties of the prosthetic components. Crucially, few studies consider the combined mechanical properties of both the prosthetic components and socket interface. Most studies have compared different commercially available prostheses, but without quantitatively characterising their mechanical properties (or the socket’s), so that they are often differentiated by their trade names only. Such studies only tell us which commercial device is better, but not why, and therefore do little to inform the design process. Hence, it is perhaps unsurprising that it remains almost impossible for researchers, designers or clinicians to predict amputee comfort and performance with a given prosthesis. All of these problems have meant that advances in lower-limb prosthetics have been primarily the result of trial and error based development, thereby progressing slowly. So a more holistic approach is needed, where the relevant properties of the socket interface and distal prosthesis are measured (and modelled) as well as the quality and efficiency of the corresponding amputee gait. The resulting correlations can then provide independent, objective and quantitative data to inform design and prescription. Therefore, it is vital that future studies objectively and quantitatively record the functional properties of the socket interface and distal prosthesis in a way that recognises their mechanical coupling. This is the key to a better understanding of how prostheses can be optimised and, in particular, personalised to suit the individual amputee. Ongoing work at Salford is addressing this difficult problem through a combination of experimental work and modelling
Salford team: Prof Laurence Kenney, Prof David Howard, Dr Martin Twiste, Dr Anna Pace, Dr Matty Major. External partners: Dr Matty Major (NUPOC, Northwestern University, Chicago), Prof Liudi Zhang (Southampton University), Dr David Moser (Blatchford Ltd).