Hybrid Prosthetic Vacuum Pumps for Lower Limb Amputees

NU 2011-089B

Primary Inventors

Stefania Fatone*

Matthew Major*

Ryan Caldwell

Andrew Hansen

Short Description

Unique prosthetic solutions that include multiple designs of hybrid (mechanical and electrical) vacuum pumps

Background

There are approximately 700,000 amputations annually, generating a $1Bn prosthetics market. The current market includes either mechanical or electrical pumps, but hybrid pumps that combine electrical and mechanical aspects have not yet entered the market. Further, there are limited in-line pumps for transfemoral amputees outside of the OWW LimbLogic and Otto Bock E2 pumps. Persons with amputation prefer prostheses that provide maximum functional restoration and comfort. Vacuum assisted suspensionreduces relative motion between the prosthetic socket and residual limb, improving force transfer, function, comfort and soft tissue health. However, current prosthetic vacuum pumps, being either mechanical or electrical, can be noisy, have a tall build height, and/or take time to generate vacuum. There is need for a vacuum pump of low build height that can work quietly, and quickly generate vacuum when desired while conserving battery life throughout the day.

Abstract

Northwestern scientists have developed a unique suspension system for prosthetic devices that include mechanical and electrical pumps. The mechanical aspect of these designs use either a bladder or a diaphragm to create negative pressure. Both designs have a lower build height than commercially available mechanical pumps, making them suitable for use in-line with sockets, especially in transfemoral (above-knee) prostheses. Working in concert with an electrical pump, both hybrid pump designs offer the quietness of mechanical actuation, with the speed of electrical actuation. Various suspension systems have been developed for coupling a prosthetic limb to a residual limb. Our earlier bladder-based hybrid pump design generated a clinically acceptable level of vacuum but was less robust to out-of-plane movements during compression than the subsequent diaphragm-based design. While both designs provide for a lower build height than existing mechanical pumps, the space savings are greater with the diaphragm-based design.

Stage of Development

A prototype has been built and tested (Publication). View testing video.

Stage of Commercialization

The technology was presented at OTWorld 2016, an international tradeshow in Leipzig, Germany.

Applications

• A mechanism to hold the prosthetic socket onto the residual limb for lower-limb amputees

Advantages

• Hybrid function: Unobtrusive, quiet operation and minimal need for battery recharging
• Small build height for transfemoral amputees (suitable for placement between the prosthetic knee and socket)
• Improvement upon the size and function of existing prosthetic vacuum pumps
• Minimal displacement/excursion required by diaphragm to function and hence minimizes range-of-motion added to prosthesis
• Optimization of the size and function of existing prosthetic vacuum pumps

Publications

Major M, Calldwell R, Fatone S (2015). Evaluation of a Prototype Hybrid Vacuum Pump to Provide Vacuum-Assisted Suspension for Above-Knee Prostheses. Journal of Medical Devices. 9(4): 0445041-445044

IP Status

Issued US Patent Nos. 9,066,822 and 9,757,255. An international application has been filed.