RESEARCH TRIANGLE PARK, NC – It has been well documented that the insulating environment created by the socket of the prosthetic results in an increase in skin temperature in that region. One Department of Veteran Affairs commissioned study found that mean skin temperature of the residual limb of a patient with a transtibial amputation can increase by 0.8˚C just from donning the prosthetics and resting in the seated position for 15 minutes. After 10 minutes of walking the increase can exceed 1.7˚C. It is easy to envision that the temperature can increase substantially more as amputees are more active. These elevated skin temperatures can contribute to major skin irritation, dangerous blistering and subsequently a reduced quality of life.
Traditional water cooled solutions cannot be successfully implemented to address the heat buildup issue for several reasons. The tubing size required to allow water to be pumped at acceptable pressure levels exceeds the diameter that can be comfortably worn by the amputee. Furthermore the weight associated with water, ice, pump and battery source makes the solution impractical. Air cooled solutions are also impractical. Venting air within the liner would compromise the vacuum and make it impossible to secure the prosthetic limb satisfactorily. As a result, while major advances have occurred in the design, manufacture and performance of prosthetic limbs over the last two or three decades, very little has been done to address the heat buildup issues in the residual limb. Until now…
Porticos, Inc. has teamed up with the South Carolina based Advanced Technology International (ATI) dba SCRA Applied R&D to develop a cooling solution based on the Porticool liquid CO2 technology invented by Porticos. The prototype generated excitement and interest at the Annual Meeting and Scientific Symposium of the American Academy of Orthotists and Prosthetists where it was unveiled last December. According to Christopher Norfolk, PhD, SCRA R&D program manager, “We’ve found that the system can be effective, comfortable for patients, and that liner materials are not an impermeable barrier to the cooling effect based on this proof of concept prototype”.
Initial testing conducted by Georgia Institute of Technology Master of Science in Prosthetics and Orthotics program co-director and prosthetics coordinator Rob Kistenberg, MPH, CP, FAAOP has been very promising. “We are excited about this concept”, says Mr. Kistenberg. “Initial patient tests demonstrated that for mild exercise the cooling device eliminated almost 90% of the total temperature rise”. Testing continues to characterize the optimal cooling rates for the system and how the system interacts with various prosthetic suspension options.
Adapting the Porticool technology required Porticos engineers to ideate new solutions to reduce the cooling flow to a rate more compatible with the level of cooling required by the amputee cooling application. Extensive testing was conducted in the Porticos lab to characterize the solutions and confirm cooling targets and flow rates were being met. Due to the limitations in space, the engineers designed a new manifold with an integrated custom back pressure regulator along with a completely new custom enclosure. “It is exciting to have the opportunity to work on a project that can improve people’s lives”, reflects Porticos president Greg Patterson, “and it gives the team a sense of pride to realize that technology developed by Porticos will be an instrumental part in the success of the project”.
While encouraged by the progress to date everyone on the project acknowledges that there is still work to be done before the product can be brought to the market. The vision for the commercialized product is a much more integrated solution that resolves the heat issues currently experienced by amputees without impacting freedom of motion.
About Porticos — Porticos, Inc. is a mechanical engineering and product design development company located in Research Triangle Park, NC. Established in 2003, Porticos continues to produce innovative and effective solutions for its clients and the markets they serve. Porticos, Inc. provides mechanical design, analysis, research and development services to clients including Dell, Motorola, Raytheon, and many others. For more information on how Porticos “turns good ideas into great products,” please visit www.porticos.net
About SCRA — SCRA is an applied research corporation with over 30 years of experience delivering technology solutions with high returns on investment to federal and corporate clients. To fulfill our mission, SCRA has three sectors: Our Technology Ventures sector helps early-stage companies to commercialize innovations and create jobs, our Applied R&D sector manages over 100 national and international programs worth over $2 billion in contract value and our R&D Facilities sector builds and manages research facilities that include wet labs, secure rooms for sensitive work and advanced high-tech manufacturing shops. Multiple economic output studies show SCRA’s cumulative impact on South Carolina’s economy to be over $14 billion, and that the company has helped create approximately 15,000 technology-related jobs in SC, with wages averaging between $55,000 and $77,000.