Prostheses can be suspended from the amputated limb using a variety of techniques, such as straps and suction. Suspending the prosthesis by creating a vacuum between the prosthetic socket and limb using a pump has benefits over other techniques including improved limb health and mobility. A new pump design will be tested by prosthesis users in the laboratory to verify its functionality during walking.

Human subject testing will involve a cross-sectional, repeated measures study consisting of a single 3 hour visit wherein participants will initially stand and then continuously walk at their self-selected speed for ten minutes on a level treadmill with the prototype under two randomly presented conditions of the mechanical system: 1) fully functional, and 2) locked to restrict axial displacement. After written informed consent is obtained, information on socket comfort and mobility capability will be collected. A load-cell will be installed proximal to the prototype and in-line with the prosthesis to measure instantaneous socket-reaction moments.

Inclusion Criteria:

• Ability to stand quietly and walk for 10 minutes continuously without an assistive device (e.g. cane or walker) and without undue fatigue or health risks
• Pre-classified clinically to be at least a limited community ambulator of Medicare Functional Classification Level (K)2
• Residual limb in good health
• At least six months experience with a definitive prosthesis that utilizes vacuum assisted suspension

Exclusion Criteria:

• Pathologies aside from amputation or taking medicine that would influence walking or balance
• Poor prosthetic fit or poor residual limb sensation