Mechanically and Physiologically Optimizing Prosthetic Elevated Vacuum Systems in People with Transtibial Amputation: A Pilot Study

Introduction The most suitable elevated vacuum (EV) pressure may differ for each individual prosthesis user depending on suspension needs, socket fit, prosthetic components, and health. The mechanical and physiological effects of EV were evaluated in an effort to determine the optimal vacuum pressure for three individuals. Methods Instrumented EV sockets were created based on the participants’ regular EV sockets. Inductive distance sensors were embedded into the wall of the socket at select locations to measure limb movement relative to the socket. Each participant conducted an activity protocol while limb movement, limb fluid volume, and user-reported comfort were measured at various socket vacuum pressure settings. Results Increased socket vacuum pressure resulted in reduced limb-socket displacement for each participant; however, 81% to 93% of limb movement was eliminated by a vacuum pressure setting of 12 (approximately −9 inHg). Relative limb-socket displacement by sensor location varied for each participant, suggesting distinct differences related to socket fit or residual limb tissue content. The rate of limb fluid volume change and the change in socket comfort did not consistently differ with socket vacuum pressure, suggesting a more complex relationship unique to each individual. Conclusions Practitioners may use individual responses to optimize socket vacuum pressure settings, balancing the mechanical and physiological effects of EV for improved clinical outcomes. Clinical Relevance Understanding the effects of various socket vacuum pressure settings on individuals’ outcomes may improve clinical implementation of EV. In this study, the highest available vacuum setting did not always produce maximum comfort and limb fluid volume benefit, and similar levels of suspension were achieved with lower vacuum settings.