A low-cost volume adjustable lower limb prosthetic socket : design and evaluation



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An issue of great concern for amputees continues to be lack of proper fit and comfort in their sockets. This lack can often be attributed to changes in the shape of the residual limb that cannot be compensated for by existing prosthetic socket technology. In regions where cost is a prohibitive factor in the replacement of ill-fitting prosthetic sockets, the need for a volume adjustable, and potentially longer lasting, socket design is abundant. This research focuses on designing a volume adjustable lower limb prosthetic socket that accommodates the needs of amputees in underdeveloped countries using collaborative design techniques. Though advocated as a means of accurately identifying and satisfying their needs, including end-users in the design process often adds an additional layer of complexity because of differences in culture, language, or geography among the participants. This research therefore includes a study in which product design techniques were applied to the same volume adjustable socket design problem with a variety of users – typical users, lead users, and new Empathic Lead Users - from different countries, one developed and one developing. To overcome differences among participants, this research includes an alternative strategy to create Empathic Lead Users (ELU) from non-user product design engineers through the use of simulated lead user experiences. As a result of this study, customer needs analysis with ELU helps to identify 95% of traditional and lead user customer needs and 100% more latent needs, and possibly more avenues for product innovations, than interviewing lead or traditional users alone. The concepts generated by all users were also compared. Based on the resulting concepts’ novelty, variety, quality, and quantity, all users were able to satisfactorily complete the concept generation exercises and produced competitive design solutions. Using the concepts generated during this co-design study, a volume adjustable socket was developed. The final socket design, based on the analogous rotational movement of a camera aperture, is pursued through mechanical and subject testing. Early users of the socket liked the design and it has been demonstrated to provide the necessary volume adjustments, but future design iterations to improve its comfort are necessary.