29 Sep, 2016
Designing an adjustable prosthetic socket using ReMake and Fusion 360
Who I am and what I do
My name is Claudine Humure and I am a rising senior at Wheaton College in Norton, MA majoring in biology and minoring in business and management. I have a great passion for prosthetic limb research and design as well as working with amputees of all kinds. I got into prosthetic design during the summer of 2015 when I interned with the Biomechatronics group at MIT Media Lab under the supervision of professor Hugh Herr and three of his graduate students. Before I got into prosthetic design, I did a number of clinical internships at different locations including Next Step Bionics and Prosthetics and Spaulding Rehabilitation Hospital.
This past summer, I worked as an intern at Autodesk. My internship project was about creating a prosthetic socket for above the knee amputees using ReMake and Fusion 360 as a way to use these tools to solve a social impact challenge. Social impact design is a branch of design that seeks to find solutions for problems in low-income communities drawing ideas from cultural, environmental, and economic beliefs. It focuses on improving the lives of a wide group of individuals in a way that will contribute to the development of a country as a whole.
Using the five stages of design thinking, the project came into fruition but there is much work that still needs to be done. Design Thinking is the science of realizing and critically analyzing a certain issue and working towards creating a solution that is greater than already existing or attempted conclusions. This term is often broken down into five categories: Empathize, Define, Ideate, Prototype, and Test/Iterate. During my design process, I used these five categories to guide my project.
Inspiration and background
The inspiration to work on designing a prosthetic socket came from my experiences as an above the knee amputee living in Rwanda. Rwanda is a developing country with a population of approximately 11 million. Unfortunately, there are no known statistical data to indicate exactly how many amputees there are in Rwanda, but a large number of the population were left handicapped due to the 1994 genocide that took the lives of more than 800,000 innocent people. Like many handicapped people in developing countries, amputees in Rwanda are at the bottom of the poverty line and therefore do not bother thinking of buying a prosthetic limb due to their high prices.
The cost of a prosthetic limb in developing countries varies greatly depending on the materials used and the region in which they are made. However, according to an article published on the Orthotics and Prosthetics (OandP) website, the overall cost of a prosthetic limb in low income countries ranges between $125 and $1,875. This price range is still a challenge for many third world country amputees as the average annual income per family living in rural areas is close to or less than $300.
General Prosthetic leg structure
The most common types of lower extremity amputations are done above or below the knee. My research focused on designing a prosthetic socket for individuals who are missing a limb above the knee. A typical prosthetic socket for an above the knee amputee consists of four different compartments:
- A socket, which is the part that comes in direct contact with the amputee’s residual limb. It is considered the most important piece of a prosthesis because an amputee will not use their whole artificial limb if the socket does not feel comfortable.
- A pylon, the limb extension, sometimes it is part of the knee.
- A knee, the piece between the pylon and the prosthetic socket.
- A foot.
Traditional and CAD/CAM methods
Today, prosthetic limbs are commonly made using conventional methods. This is where a prosthetist takes a 3D shape of the residual limb by wrapping a plaster cast around it to get a negative mold. He/she then generates a positive mold from the negative on which anatomical points are identified for even load distribution. Throughout this process, the prosthetist uses little quantitative analysis to design the socket, and as a result, the comfort level of the prosthetic socket depends on how experienced the prosthetist is. Fortunately, some prosthetists have adopted the use of computer aided design and manufacturing methods for more comfortable prosthetic sockets. However, even with CAD/CAM processes in place, most prosthetic sockets created today cause discomfort because of the daily volume changes that an amputee’s residual limb experiences.
Getting my leg cast by my prosthetist.
Images indicating the tools used in my design process from picture taking to designing in Fusion 360.
Testing will be the next step of my design process. As of right now, the image you see above in Fusion 360 has not been 3D printed for testing yet. More designs will be made in the future to better improve the comfort level of the prosthetic socket. I also need to do some quantitative analysis to determine how much load the socket should be able to handle and where the pressure points should be according to my residual limb geometry. ReMake and Fusion 360 have the potential to change the standards of prosthetic limb design for the better. With these tools, great design can be achieved especially when designing for social impact. Once this prosthetic socket has successfully been designed and is ready for use, impact will be measured by keeping count of the number of users in the developing world who will be able to use it with great comfort and success.