Redesign of a Volume Adjustable Transtibial Prosthetic Socket

Recent research and development in prosthetics have aimed at improving socket designs and components to mimic more efficiently the human body. One such innovation is the Aperture Socket, a low-cost volume adjustable prosthetic socket. During the validation stage of its development, the Aperture Socket successfully demonstrated that it could compensate for volume changes, but various improvements on use and comfort were identified. This project develops and tests a redesign of the Aperture Socket previously developed for amputees in developing countries and subsequently patented and licensed to LIMBS International, Inc. The first phase of this study was the creation of various prototypes to improve the existing mechanism for adjusting the prosthetic socket. The adjustment system was redesigned to improve ease of use and provide a more stable coupling between the socket and the remaining prosthetic components. The second phase consisted of creating a new socket wall design that implements struts with a flexible inner socket. The new socket system was designed to provide greater support to the residual limb, to improve user comfort, to simplify the manufacturing process, and to lengthen the lifecycle of the product. The third phase was experimentally testing the prototype with mechanical compression machines, following guidelines dictated by the ISO 10328:2006, and user feedback. One experienced transtibial amputee rated at the K3 activity level was selected to validate comfort, volume adjustability, and ease of adjustment of the redesigned Aperture Socket while performing the L-Test of functional mobility [7]. The results of the ISO 10328 ultimate strength test showed that the socket design struts are not capable of supporting the ultimate load applied during the late stages of the gait cycle (P5 level, condition II). However, the axial load test of the ultimate strength force was successfully passed, which shows that the socket system is capable of withstanding the ultimate strength force of 4025N. The results from the subject trial concluded that the socket redesign was successful in adjusting its volume in a friendly manner while providing a comfortable fit and natural gait