Analysis and Design of a Bypass Socket for Transradial Amputations

Abstract

The ability to measure functional performance of a prosthesis is hindered by the lack of an equalized mechanical platform to test from. Researchers and designers seeking to increase the pace of development have attempted novel mounts for prostheses so these can be used by able-bodied participants. Termed "bypass sockets", these can increase the sampling pool during prosthetic evaluations. Here, we present an open-source, 3D printable prosthetic bypass socket for below-elbow (transradial) amputations. Methods to quantify the effectiveness of bypass sockets are limited and therefore we propose the use of a validated and clinically relevant evaluation tool, the Assessment of Capacity for Myoelectric Control (ACMC). We performed the ACMC in six able-bodied subjects with limited experience with myoelectric prostheses and found the participants to be rated from "non-" to "somewhat capable" using the ACMC interpretation scale. In addition, we conducted a secondary evaluation consisting of a subset of tasks of the Cybathlon competition aimed at eliciting fatigue in the participants. All participants completed said tasks, suggesting that the bypass socket is suitable for extended use during prosthesis development.Clinical Relevance-The design and validation of the bypass socket presented here can facilitate the development of upper limb prosthetic systems.

How the CYBATHLON Competition Has Advanced Assistive Technologies

“…Some of the proposed tasks involve grasping and manipulation actions in different arm postures-for example, grasping and releasing objects on a bookshelf, or performing the wire loop task-to validate the coordination between multiple joints and the reliability of the control method. All of these characteristics make the tasks of the competition a valid alternative to standard assessments for a preliminary evaluation of novel approaches in the laboratory environment (e.g., 67,68).…”

Evaluating the effect of non-invasive force feedback on prosthetic grasp force modulation in participants with and without limb loss

“…While it is important not to translate findings from the able-bodied cohort into clinical applications for those with limb loss, able-bodied cohorts with simulated functional limitations are sometimes studied when sampling with proper power would be too time and resource intensive [ 32 , 33 ]. Findings from an able-bodied cohort can then help refine research questions for future clinical trials for persons with limb loss, such as the work done by Fu et al who demonstrated that inter-limb training improved participants’ ability to grasp a targeted force [ 33 ].…”

Knee Angle Generation with Walking Speed Adaptation Ability for a Powered Transfemoral Prosthetic Leg Prototype

“…To evaluate the validity of the algorithm, most current studies utilize bypass sockets to verify the result by healthy participants for the performance evaluation of the prosthetic legs. Some researchers have been working on the design of an open-source, low-cost bypass socket [26,27], allowing more convenient simulation. However, this tool lacks the simultaneous reference of the actual walking pattern, which may lead to inaccuracy of comparison between natural and prosthesis-assisted walking.…”