Better, Faster, Smarter: Why More Clinicians Are Trying 3D Printing for Lower-limb Prostheses

Debate and discussion continue among O&P professionals about the feasibility of applying additive manufacturing methods to the creation of lower-limb prosthetic sockets, but proponents point to welcome economies and efficiencies associated with the process. Waste Reduction Tony Gutierrez, CP, national clinical specialist for Bionic Prosthetics and Orthotics, headquartered in Indiana, led Bionic’s early adoption of additive technology, prompted in part by economic concerns. “When we fabricated a traditional socket, we saw waste in many applications: We had to buy a $50 sheet of plastic, though half the material was wasted—we just threw it away. Whereas printing with the FDM filament, we have only 8-10 percent waste.” Zach Brown, digital technician, Bionic, points out that with traditional prostheses, there’s always a chance of human error during the fabrication process. In addition to the loss of materials, there is the redundant cost of time spent on making up for those mistakes. A lack of consistency also contributes to waste. “We know that our machine’s output is consistent, and we’ve shown it over time.” Gutierrez explains. “That consistency enables us to prevent the mistakes that we see in standard fabrication, where sometimes the vacuum form is uneven: too thick in one area, and too thin in another area. “That leads to costly waste, especially as the costs of materials are going up. The cost could be anywhere from $25 to $200 for a traditionally fabricated [socket made from] plastic material, depending on the size of the limb, compared to $10 to $40 for the equivalent printed materials.” “When you talk about additive, we are recycling and reusing 80 percent of the powder that we start with,” says Joe Johnson, CP, owner of Quorum Prosthetics, Colorado. “When we build a socket, we have a cube of powder, and from it, we can build five sockets overnight. Whereas typically one technician can make maybe two sockets a day using traditional fabrication methods. So we save that one person (of manpower) by having the printing done overnight.” He points to another money-saving efficiency achieved by using Materialise Magics optimization software to nest multiple parts, strategically positioned and spaced to print as many as possible from the same cube of powder at the same time. “So not only are you recycling,” Johnson notes, “you are also conserving on energy and manpower. The future looks really good when you’re thinking that way.” Time and material economies are evident in other aspects of 3D printing, as well. The flexible inner liner of a transfemoral or transtibial socket is typically paired with a rigid outer shell. As the residual limb continues its natural shrinkage over time, the user adds thicker socks until a new socket is needed, Johnson explains. “When I need a new socket now, however, we have the option of remaking only that flexible inner liner, printing it from thermal plastic urethane (TPU). I can make that inner liner 3 percent thicker if I know the patient is in a six-ply sock or a nine-ply sock, since I can equate those thicknesses to a percentage. Now I can reprint only the inner liner and not have to reproduce the entire socket. “I could never do that before, because I could never really duplicate that inner liner to fit inside the definitive socket before.” Sean McClure, BME, ME, research and development engineer and director, Quorum Prosthetics, agrees. “When a patient loses a lot of volume and needs a fit change, we have digital records of their molds and their shapes; so, we can modify them and reprint the corrected socket—or just thicken the inner socket to the inside and print that without having to replace the entire socket.” “ Once the payers understand this,” Johnson says, “this will be kind of a new revolution that’s happening in lower-limb prosthetic care. And because I keep that digital file forever, I don’t have to keep and store casts anywhere. I just go back to that digital file and retrieve it and reprint. The many benefits of 3D are just amazing.” Technical Efficiency, Clinician Effectiveness “A recent article in O&P EDGE compared a clinician’s time from this year to time spent professionally in the mid-1990s,” Gutierrez recalls. “In order for today’s clinician to be as effective and efficient from a financial perspective as they were in the late 90s, they’d have to see three times as many patients a day. This just illustrates how the cost of business and the reimbursement climate are affecting profitability. “So if you’re stuck in the lab playing with plaster instead of interacting with your patients and your medical community, your practice is going to have a hard time growing.” McClure adds that 3D printing seems to be increasing Quorum’s economics by complementing the digital workflow that has already demonstrated significant business increases. “Using this digital workflow and additive does open up the practitioners’ time to see more patients. They spend less time on fabrication themselves, and sometimes can do modifications digitally, so the practitioner doesn’t need to be in a plaster room, spending time modifying, redoing sockets, or having to pull extra check sockets. “If somebody comes in for a socket replacement, they have a bit of a head start, so they can see the patient for 15 to 30 minutes, go over all the adjustments that need to be made, and then hand off those modifications to the designer while the practitioner sees other patients,” he says. “And as far as fabrication, we can actually deliver replacement sockets faster since we have that head start, with the digital socket design conveniently accessible. If no modifications are necessary, it can be printed and ready by the next day, leaving the practitioner with extra time to focus on patient interaction.” Such instances of faster delivery and improved efficiency are economies in themselves. Gutierrez points to the rapid strides 3D workflow has made since Bionic got its first 3D printer five years ago, when it took about 48 hours to print a transtibial check socket. “It really wasn’t practical, the quality was very low, and one of the issues that we discovered was that the PLA material those early printers used is not typically used in prosthetics. It’s very brittle, very thin, and not very strong. It was just not a material that O&P clinicians were accustomed to working with, and that led to difficult adoption. But it was an important first step, and we’ve come a long way since then.” Now, he reports, they’re utilizing high-flow FDM printers from Filament Innovations, which are considerably faster than their original standard-flow machines, which required eight to ten hours to print a transtibial socket. “As we transitioned to high-flow printing, we were able to print in layers that were 4mm thick. By doing that, we weren’t printing honeycombed structures anymore, we were actually printing a solid piece of plastic, which was consistent with industry standard plastics used in 3D printing of prosthetics.” Gutierrez reports that their workflow has probably transitioned on the diagnostic side to probably 95 percent digital/printing, now utilizing PETG, the industry standard previously used for traditionally fabricated diagnostic sockets. Until recently, Brown was able to singlehandedly print 90-100 diagnostic sockets per month, supplying all Bionic’s clinics. To accomplish this in a lab, with traditional fabrication, would require three or four full-time technicians, Gutierrez estimates. “What really made me a true believer in the process of additive workflow,” says Gutierrez, “was the day I had taken casts of seven amputee patients I expected to see for their check socket fittings in two days, and I had a family waiting at home.” Instead of making two one-hour round trips between his home and the lab, then working in the shop till 2 or 3 a.m., he was able to take digital scans of all seven casts and send them to his home where he created digital modifications and sent them to the printers. “When I came in the next day, half of the projects were already done.” From a technical perspective, Brown points to the manpower-intensive investment in producing definitive sockets for patients, and the difference the printers make in reducing that investment. “If we have the machines running say, an hour and a half per print, that frees up so much time for our technicians to focus on not only the projects we have going, but fabricating complex definitive sockets designed so our clinical team can deliver them to our patients in a timely fashion. The traditional time investment would be two to three hours to complete a diagnostic socket workflow manually, where with a digital workflow and 3D printing, I can knock out five sockets in an hour and a half, depending on the printers and how we utilize them. So that’s one efficiency from a purely technical standpoint.” Better Patient Care Beyond freeing up clinicians to spend more time with patients, additive still has more to offer in the arena of quality patient care. “I don’t have a printer here,” admits Shane Grubbs, MPO, CPO/L, ProCare Ottobock.care. “But I’ve been working with software experts and exploring printing possibilities for the last three or four years. What attracted my interest was the potential for creating more dynamic sockets for patients out of new materials. I really started to see some benefits from the new polymers and the different physical properties of the physical compounds they’re using and the different style of printers that are evolving.” He began hearing from other experimenters and trying to help develop some of their ideas for his own patients “just to get better outcomes.” He’s pleased with his own experimental results, and committed to making use of additive advantages, but cautious. “We’ve done a lot of printing for covers and test sockets and things like that, but as far as adopting it for everything that we do, I don’t think we’re there yet. We’re still in the recognition phase, trying to get everybody to the uptake phase of it is very challenging. The aspects of 3D printing technology that make us more efficient are very appealing to businesses, and I think the part where we can improve the devices that we provide to patients is what will get care providers more on board with it.” Grubbs cites several patients who have benefited from new device designs that would have been impossible using traditional fabrication, like the flexible prosthesis printed for a marathon runner, and the fully printed arm that allowed a US Marine to do pushups and rowing. “We were able to print the arm including the hinges, which allowed for a reduction in weight and eliminated some of the traditional fabrication challenges.” Derick Schmidt, MPO, CPO, Limb and Lattice, Shore P&O, and Presque Isle Medical Technologies, US Virgin Islands, also refers to aspects of additive manufacturing that enable fresh patient care solutions, like “print in place” parts that have multiple segments interfacing and articulating with each other, which are printed as a single piece. “Since some of these really unique projects may have to be remade more than once,” Grubbs notes, “it’s convenient to have the design stored and ready to print, so you can just make alterations. That’s a lot easier than going back to laminate it a second time.” The act of mixing methodologies—old with new fabrication techniques—offers additional potential for better patient care solutions, he says. “I still like doing soft tissue manipulation under vacuum for creating a mold and test socket because I get really good results. Then I scan that mold and do my printing. So you can mix it together, and maybe that’s where you get more adoption, too, when people realize that you don’t have to get rid of all your experience and all your knowledge when you jump into something brand new,” Grubbs says. “You have to remember how O&P professionals got into this—what our values and our passion is. It’s helping people—it’s blending science and art to help people.” “As a tech,” Brown agrees, “additive allows me to open up the clinician’s day to go see more patients, deliver more prostheses, connect with doctors, and expand our reach within the medical community—while I’m able to work on cast modifications, digital modifications, or future patients. “I think 3D is the way to go from both an efficiency and an improved patient care standpoint.” Schmidt disagrees. “I could only list maybe five clinics that I know of who are regularly using 3D-printed definitive lower-limb sockets. I still don’t do it because I can’t justify the cost. Use of printed test sockets and other types of devices are spreading far more quickly than definitive lower-limb sockets. At the end of the day, we run businesses, and products that make good financial sense and improve profit margins will find a market much easier than products offering unclear benefits at higher price points. “We only have to look as far as orthotics to see what that looks like. There are 3D-printed lower-limb orthoses offering improved comfort and functionality and they are competitively priced with traditionally fabricated orthoses. I use those regularly with good outcomes for both adults and pediatrics. The potential is there for definitive prostheses, but there is still work to be done before that segment is market ready.” Experience Makes True Believers Clinicians beginning the 3D printing experiment often lack faith that the process can work, that it can be faster and more accurate, says Gutierrez. “But once they learn the recipe, about six to nine months into their digital journey, the conversation changes to ‘There’s no way I could see ever going back. The work of casting a patient to creating a socket design ready for fabrication used to take me an hour and a half—now the process is done in seven minutes!’ “The amount of time that we’ve given people back into their day is a huge benefit. When I started practicing in 2010, I felt that I spent 90 percent of my time with the patient, and 10 percent dealing with administrative issues. In the past ten years I feel like it’s completely flipped to where maybe 10 percent of my time is spent with the patient, and 90 percent of my time is spent trying to make sure that our practice gets reimbursed for our services. What additive manufacture has done for me is given me time—time that I can spend with my patients—time that I can spend with my family. I don’t have to be in the lab overnight trying to get projects done on a consistent basis, because I have some tools that I can utilize—and they don’t complain. They work like a crockpot—you turn them on and go; then dinner’s ready when you get home.” To those willing to take the leap of faith that has rewarded others, Gutierrez recommends placing trust in the machines that have delivered results for Bionic: “I would definitely credit a lot of our success to Filament Innovations, the company that built a printer that is focused on expediting care in prosthetics and prosthetic applications.” The groundswell of interest and support for the 3D printing movement is already well underway. Five or six years ago was the first time you might have seen a printer at one of the large O&P trade shows; now, a third of the show is digital technology—an indicator of people’s interest in starting to utilize it in different aspects of their practice. Grubbs agrees that the time is right to seriously consider the benefits of additive manufacture in your own environment. He feels that it’s worthwhile to absorb the costs in the short term, while expanding one’s knowledge base and becoming more comfortable with additive’s potential. “I don’t think 3D printing is one of the innovations in our manufacturing that’s going to go away. It’s developed rapidly over the past five years, while so many other industries are very committed to printing. “One of the difficulties for us in O&P is always the scalability of the technology, because everything we do is custom. But even considering that, some of the larger printers are printing plastic at the rate of seven sockets at once. Such a capability should make additive more economical and attractive to payers, too. “My interest has been in making things more dynamic and functional for patient outcomes,” Grubbs stresses. “From what I’ve seen and been involved with, that’s happening with 3D printing technology. That’s what excites me about it. I’m fine with things becoming faster—and economical makes it more interesting, but I don’t necessarily want things to be easy. I just want them to produce better results for our patients.”

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