Exploring the effects of increased socket-residual limb coupling integrity via vacuum assisted suspension on prosthetic control: a preliminary study in transtibial prosthesis users.

PURPOSE: The prosthetic socket provides the critical interface between prosthesis and residuum. The purpose of this pilot study was to explore the effect of altering socket-residuum coupling integrity on limb and body control, through the use of vacuum-assisted suspension. A secondary purpose was to explore the potential use of two measurement tools designed to assess mobility in a clinical context.

MATERIALS AND

METHODS

Individuals with unilateral transtibial amputation performed intentional sway (n = 7) and treadmill walking (n = 6) tasks at three vacuum levels. Sway deviation from a straight-line path to peripheral targets was measured using an instrumented balance platform. Step width variability and targeting accuracy were measured using an augmented reality treadmill.

RESULTS

There was a significant difference in intentional sway performance toward the target on the anterior diagonal toward the prosthetic side (p = 0.036); higher vacuum levels tended toward less deviation from a straight-line path. We found no group differences between total intentional sway deviation, step width variability or stepping accuracy across vacuum levels.

CONCLUSIONS

Improved socket-residuum coupling integrity via vacuum may have measurable effects on functional control that warrant further investigation. We highlight limitations of the clinical testing paradigms to inform future work.Implications for rehabilitationThe fit of the socket is a critical factor in the success of lower limb prosthesis use.Vacuum-assisted suspension modifies the coupling between the residuum and socket.Changes in socket-residuum coupling may lead to measurable differences in control; however, these may be activity and person-specific.Clinically intended instrumented tests of movement function derived for an intact anatomy should be used with caution when assessing prosthesis users.