Of all the uses that 3D printing technology has provided the medical field with over the past few years, none show as much immediate impact as the production of assistive devices. From communities in Uganda to the veterans of the United States, 3D printed prosthetics have helped improve the lives of many children and adults around the world. Now, Emelie Strömshed, a Master’s student in product development at the Sweden-based Lund University School of Engineering, has developed a simplified process involving a trio of 3D technologies. The process has already helped to create a custom prosthetic arm socket for a young girl named Neya Pfannenstill.
Strömshed has developed a step-by-step process to create the perfect-fitting prosthetic limb, aimed to provide an easy-to follow guide to prosthetists who don’t have a full grasp on CAD. With her research, Strömshed set out to prove that a combination of CAD modeling, 3D scanning, and 3D printing could be used in a simplified process to create more efficient and better fitting prosthetic devices. The process begins with 3D Systems’ iSense 3D Scanner, a low-cost accessory that transforms an iPad or iPhone into a 3D scanner. First, Strömshed offset the limb surface at a distance that was equal to the desired thickness of the 3D printed socket, which was then subtracted from the original 3D scan to create an inner surface that fit Pfannenstill perfectly.
Strömshed’s step-by-step process
After the scan is repaired and offset to create the hollow socket, the prosthetic design is shaped and smoothed out, imported with electrode modules, and given a unique pattern to suit the preference of the wearer. These electrode modules are then subtracted after the pattern is developed, and are inserted back into the ready-to-use 3D printed socket at the end of the process. The final design is then 3D printed — in Strömshed’s case at least— with a selective sintering system in a strong nylon material, which can also be colored if desired.
Neya Pfannenstill with her new 3D printed prosthetic arm socket
Compared to the traditional methods of prosthetic manufacturing, which generally require skilled manual crafting and a costly amount of casting and molding, Strömshed’s method looks to be a major advancement. Strömshed’s simplified process is meant to give prosthetic technicians without advanced CAD skills the means to produce a perfectly fitting prosthetic socket with 3D printing. Not only did she manage to create a optimal fitting prosthetic for the young Neya Pfannenstill, a time and cost comparison also showed the potential to save around 400 hours and 261,000 Swedish Krona (approximately $32,576 USD) per year by using Strömshed’s process.
Strömshed’s comprehensive research was supervised by Christian Veraeus, a prosthetist from Aktiv Ortopedteknik, and Olaf Diegel, a professor of product development at Lund University. Professor Diegel is well-known in the maker community for his work with 3D printed instruments, and has created a number of 3D printed guitars—one of which was played by Steve Miller Band’s Kenny Lee Lewis— and even a 3D printed saxophone.
