Biomechanical Analysis of Gait Kinetics Resulting From Use of a Vacuum Socket on a Transtibial Prosthesis

The technology and design of lower limb prosthetics have evolved greatly since their introduction. The current study proposed to compare the effects of a conventional pin socket attachment and a vacuum socket attachment for a transtibial amputee. Whereas traditional measurements of gait utilize force plates and camera systems, this study made use of a small tri-axial load cell located at the base of the socket to measure the forces and moments exerted during a regular gait cycle. The hypothesis tested stated that a vacuum pump socket attachment, when compared to a non-vacuum (pin) socket, will have a significant effect on the forces and moments developed during gait. The forces and moments load the residual limb and it is generally believed that a vacuum socket will produce a more favorable loading than a conventional pin attachment socket. If changes in forces or moments can be measured, this may provide clinical evidence supporting the use of vacuum pumps on prostheses. The hypothesis was tested using a Student-t -test which compared the maximum resultant force and moments during heel strike and toe-off between the vacuum and pin systems. Two subjects, S1 and S2, were tested with both vacuum and pin attachment sockets. S1 exhibited a statistically significant effect on toe-off when wearing the vacuum socket. The rest of the variables showed no statistical significance due to the vacuum socket. S2 did not exhibit a statistical significance due to the vacuum socket during heel-strike or toe-off. The beneficial effects were not established by the results alone, but the literature review and subject assessment of a vacuum pump prosthesis offered support for the general conclusion that vacuum pump sockets produce beneficial gait outcomes. Further analysis is needed to examine the effects on the forces and moments that occur on the sagittal, frontal, and transverse anatomical planes to determine whether use of a vacuum socket results in more or less force and moment when walking. Also needing further examination is whether a vacuum socket helps to stabilize the gait of a transtibial amputee