ABSTRACT: Introduction: There is increasing evidence to support the benefits of vacuum-assisted suspension (VAS) as a means of securing lower-limb prosthetic sockets to the residual limb. As use of VAS increases, there is need to assess comparative effectiveness of different vacuum pumps. This study conducted in vivo tests to evaluate the effectiveness of two commercial electric pumps, the Ohio Willow Wood LimbLogic and Otto Bock Harmony e-pulse, in transfemoral sockets.
Materials and Methods: Tests evaluated (1) the rate and time of evacuation for each pump to achieve a clinically recommended socket-liner interface pressure of 17 in-Hg below atmospheric pressure while 18 subjects stood quietly and (2) the number of times each pump reactivated during 10 minutes of treadmill walking by 9 subjects to reestablish 17 in-Hg below atmospheric pressure after initial evacuation.
Results: During quiet standing, each pump displayed an S-shape temporal profile of vacuum pressure until 17 in-Hg below atmospheric pressure was achieved. Across participants, the LimbLogic pulled vacuum at a faster rate than the e-pulse (62 vs. 39 in-Hg/min) and required less time to achieve the desired pressure (22 vs. 27 seconds). However, the LimbLogic reactivated once during walking to account for vacuum leakage, whereas the e-pulse did not reactivate.
Conclusions: The small differences in outcome metrics between pumps suggests that they were comparable in terms of effectiveness for creating and maintaining VAS of transfemoral sockets. This study describes simple methods that can be used in future studies when comparing electric vacuum pump performance.
MATTHEW J. MAJOR, PhD; RYAN CALDWELL, CP; and STEFANIA FATONE, PhD, BPO(Hons), are affiliated with Northwestern University Prosthetics-Orthotics Center, Northwestern University, Chicago, Illinois.
MATTHEW J. MAJOR, PhD, is affiliated with Jesse Brown VA Medical Center, Chicago, Illinois.
RYAN CALDWELL, CP, is affiliated with Scheck and Siress Prosthetics & Orthotics, Schaumburg, Illinois.
Funding: The US Army Medical Research and Materiel Command Acquisition Activity (Fort Detrick, MD) is the awarding and administering acquisition office (award number W81XWH-10-1-0744). The content of this presentation does not necessarily reflect the position or the policy of the government, and no official endorsement should be inferred.
Disclosure: The authors declare no conflict of interest.
Correspondence to: Matthew J. Major, PhD, Prosthetics-Orthotics Center, Northwestern University, 680 N Lake Shore Dr, Suite 1100, Chicago IL 60611; email: firstname.lastname@example.org