ATLANTIC CITY, N.J. — Practitioners interested in incorporating 3-D printing into fabrication should consider the process for sockets and liners, according to Brad Poziembo, CP/LP, prosthetist for Dayton Artificial Limb in Dayton, Ohio, and researcher for Prosthetic Design Inc.
Poziembo, who has printed more than 100 sockets, liner molds and immediate postoperative prostheses (IPOPs) during the past 5 years, shared his experiences and passed around some of his 3-D printed products at the New Jersey Chapter of the American Academy of Orthotists and Prosthetists Annual Meeting.
Poziembo said the earliest known use of 3-D printing to create a socket took place in 1992, when the Department of Veterans Affairs awarded a grant to Joshua Rolock (née Rovick), PhD, and colleagues at Northwestern University to create 3-D printed prosthetic sockets. Rolock used an injection molding printer to create a socket in a one-step fabrication process.
According to Poziembo, Prosthetic Design Inc. and Dayton Artificial Limb — both owned by Tracy Slemker, CPO, FAAOP, who was interested in using 3-D printing in his practice —began using the machine in 2007. Poziembo said the goal at Prosthetic Design Inc. was to solve two main issues associated with the 3-D printing fabrication process.
“By far, the top two problems are speed and strength,” he said.
With a standard, desktop 3-D printer, a socket takes 28 hours to 36 hours to print. With the original Squirt Shape machine created by Rolock, it took about 8 hours, Poziembo said. Now, after modifications made in-house, Poziembo can print a socket in 1 hour or 2 hours depending on its size. This method of fabrication also cuts out a number of steps used in traditional fabrication.
For the problem of durability, the company tried a few different methods.
“We had added new tooling, we had changed the fabrication process and we had worked with the University of Dayton Research Institute to develop a plastic material that would be conducive in terms of prosthetics and printing,” Poziembo said.
Poziembo said he can now print structurally sound, weight-bearing sockets. In addition, he can print multiple socket designs and let a patient try them all at once.
3-D printing offers similar benefits to the fabrication of liners. Poziembo noted he does not create the entire liner in the 3-D printer; rather, he 3-D prints molds of the inner core and outer cavity and places silicon between the molds to create a silicon liner. Poziembo said a custom ordered liner can take 6 weeks to 8 weeks to arrive, but he can print his own in about a day. In addition, he said patients have reported less perspiration and sliding within the liner.
There are challenges to successful 3-D fabrication. Mishaps can occur that clog up the printing process; fortunately, Poziembo said, problems with a product can be identified easily through the computer code. He also still has to cut off trim lines, a process he would like to see eliminated. Poziembo also noted some patients do not want white sockets, but raw plastic is white. Fortunately, he can now laminate sockets and make them different colors, although this adds time to the production process.
Ultimately, Poziembo said access to the technology is “making me a better prosthetist and providing better care for my patients.” Poziembo said he likes the control 3-D printing allows him to have over the fabrication process — from the height and width of the device, to the thickness and the cooling temperature. This “allows me to produce a more repeatable, reliable product,” he said. -by Amanda Alexander
Poziembo B. 3-D printing prosthetics: More than a 4th grade science project. Presented at: New Jersey Chapter of the American Academy of Orthotists and Prosthetists Annual Meeting; Nov. 4-6, 2015; Atlantic City, N.J.
Disclosure: Poziembo reports no relevant financial disclosures.