Testing an adjustable prosthetic socket in a simulated military environment

Introduction: The purpose of this study was to test the performance of an adjustable socket for transtibial prosthesis users during military relevant tasks. Methods: Investigational sockets with motor-driven adjustable panels were fabricated for each participant. Sensors to detect liner-to-socket distance were embedded in the socket wall during fabrication, and collected data were used to calculate a socket fit metric (SFM). Participants completed two military readiness assessments, the Readiness Evaluation during simulated Dismounted Operations and the Common Military Tasks, in each of three socket volume adjustment modes: static (non-adjustable), user-adjusted (using a phone app), and auto (adjusted by a controller). Socket and participant performance and self-reported outcome metrics were collected. Results: In 11 Service members or Veterans, the SFM distribution was significantly lower for the auto mode compared with the user-adjusted and static modes (P = 0.023, 0.010, respectively). The socket volume was adjusted more often (P = 0.003) and underwent a greater range of adjustment (P = 0.001) for auto versus user-adjusted. The change in pre- and post-activity socket comfort score (SCS) was not significantly different between modes. Conclusions: The results highlight the errors in socket fit in static and user-adjusted sockets and demonstrate how an automatically adjusting socket can minimize error without impeding task performance.