I-Corps: Cool Stride : Novel Technology to Improve Amputees Prosthetic Wearing

Johns Hopkins University, Baltimore MD

Investigators

Abstract

This project aims to develop technology from Johns Hopkins University (JHU) to address a common and serious problem for amputees: heat and sweat build-up under their prosthetic limb. Amputees typically wear a flexible liner made of silicone or similar material over the residual limb and under their prosthesis to provide padding and improve comfort and fit. The main drawback of the liner is that it insulates the limb, creating a very warm environment leading to excess sweating. Overheating and excessive sweat often results in rashes, blistering, and the prosthesis sliding off the limb. Active amputees must regularly remove their prosthesis and liner to remove the sweat that has accumulated. These factors can limit the motivation of amputees to exercise, thus negatively impacting rehabilitation. The JHU technology comprises a cooling liner which replaces the current liner worn under the prosthesis. The cooling liner has embedded tubing through which ice water is pumped to cool the limb and reduce sweat. If successfully developed this product has the potential to significantly improve the lives of amputees, making it easier for them to use their prosthesis and to exercise, while reducing the potential for skin damage and other problems that result from excess heat and sweat under the prosthesis. Walter Reed National Military Medical Center approached JHU to develop a solution for amputees' heat and sweat problems. This led students in JHU's Mechanical Engineering Department to create a manufacturing method to embed coolant tubes into a silicone liner, so that coolant fluid can be circulated around the limb, reducing skin temperature and sweat production. The coolant is ice water, which is stored in a reservoir (e.g. a waist pack) which also contains the circulating pump. This liner was found to be effective in preliminary tests on US Army Veteran amputees at Walter Reed. The initial product targets transtibial amputation, the most frequent form. There are approximately 350,000 transtibial amputees in the US who have prosthetic limbs and it is estimated that sales of the cooled prosthetic liner in this market have the potential to reach $25M/year or more at maximum penetration. Cool Stride was recently awarded $100,000 in funding from the Maryland Innovation Initiative to continue prototype development. This team believes that the I-Corps program will allow the team to generate feedback from amputees, prosthetists, reimbursement and regulatory consultants on these, as well as yet unknown issues, regarding the proposed product. The answers should help the team understand a) commercial potential; b) the need for minor or radical design changes; c) pricing structure; d) development and commercialization plan, and e) possible need to pivot towards a distinctly different product to solve amputee heat/sweat issues.