Is 3D Printing a New Toy or a New Tool in Pediatric O&P?
April 2021 Issue
3D printing, an idea whose evolution has come a long way in a short while, is still regarded with ambivalence by some O&P clinicians. But its value in serving pediatric O&P patients is becoming evident in cases where practitioner input is a key and early element in the creative process. With the help of O&P leaders whose pediatric patients are benefiting from 3D printing's expanding cornucopia of gifts, we explore how this science's rapid growth is being harnessed to transform young lives with fresh potential.
3D Printing Myths, Rumors, and Misapprehensions
Such an abundant mixture of truth, fiction, exaggeration, and rumor has surrounded the discovery of 3D printing and its potential for development, that Samantha Payne, COO and cofounder of Open Bionics, headquartered in Bristol, United Kingdom, offered to clear up a few misconceptions concerning the role of 3D printing in pediatric O&P devices like the bionic Hero Arm her company created.
"The first myth is that really good long-term clinical outcomes and good adoption rates can come from a person at home with a fused deposition modeling, off-the-shelf family printer with no clinical information or clinical experience," she says. "Also, a lot of people associate 3D printing with a lack of standards, regulations, or testing, but the truth is that although it is created using a similar additive manufacturing methodology, a myoelectric prosthesis like the Hero Arm, with its multi-grip functionality, must meet international standards and undergo rigorous testing by independent agencies."
Eric Shoemaker, MS, CPO, regional director, Ability Prosthetics and Orthotics, headquartered in Exton, Pennsylvania, notes that while 3D printing for children has enabled prosthetists to design and create partial hands, each of which is specific to the individual child, there are shortcomings. "We're seeing a lot of open-source designs on the internet that anybody can print out, and then scale them to the size of the individual. There are a lot of great ideas out there, but in my experience, they tend not to be very functional or durable, and they break easily."
And although the open-source items are scaled to the individual's size, "it's not really a custom fit, and the fit of a device is really what gives a person control over the device," explains
Shoemaker, who advises university engineering students on similar projects and sees the same issues.
"We got one little girl a hot pink hand. She loves it, it increased her confidence, she was proud of it, she was showing it to people. Did she use it functionally?
Not really. She put it on like it was a bracelet or a handbag. Which does serve a purpose, but we're looking for more functional performance; and that's what I think we're going to start seeing now, as things progress.
"3D printing is still in its infancy—we still have a long way to go—but I think the potential is incredible, especially since so many people are interested. But there needs to be more of a merger between those folks that are on the 3D-printing side and the clinicians," Shoemaker says. "I've talked to multiple students and companies that are working on these sorts of things, and my message to them is ‘Don't bypass the prosthetist. Create something that you can market to the prosthetist that is a viable product that he will choose to use on his patients.'"
He also cites quality and cost as major concerns. "To really create something that is a quality product, you need an expensive 3D printer. Instead of purchasing their own printer of that caliber, some facilities are looking for companies that already have them and have unused capacity. Because everything is digital, they can email their design across the country to one of these printers, and have that device printed for them. Like central fabrication but using printers.
"This is new to me in the past year, that I'm seeing these higher quality devices. So I'm guessing we're going to start seeing this cross over into the orthotic realm, as well," adds Shoemaker. "We'll start seeing 3D-printed AFOs and foot orthoses that are really of high quality and good durability, which we haven't seen to this point."
Payne says that 3D printing's popularity grew in 2013, the same time Open Bionics was founded. "Engineers and designers saw the potential of these new materials and manufacturing methods, and there was a lot of experimentation with these new tools in attempts to deliver more cost-effective prosthetic devices that could really help people."
Then, she recalls, there was a divergence. While Open Bionics focused on pursuing research and development in conjunction with clinicians and pediatric patients with upper-limb amputations, others did not. Open Bionics interviewed hundreds of people with upper-limb amputations and identified problems with contemporary prostheses, including the high price of high function, disappointing device functionality and weight—plus complaints about how uncomfortable they were to wear, how hot they got, how materials like silicone were sticky and didn't breathe, and, importantly, how their bulky, heavy, expensive, and minimally functional upper-limb prostheses made people feel.
Many upper-limb prostheses were abandoned because they were not useful enough and made amputees (especially the young) ashamed to wear them.
"There weren't many specialized upper-limb clinicians to help troubleshoot problems; and since the population of upper-limb amputees is very small," Payne points out, "a clinician's [upper-limb] experience might be limited to just a few cases in his or her professional career."
The Hero Arm's prototype design was based on features that emerged from these patient interviews.
England's National Health Service had concurrently identified upper-limb prosthetics as an area with high prosthetic abandonment that desperately needed innovation, so it funded the Hero Arm prototype for further development and testing on ten children, with feedback from clinicians, occupational therapists, and the children and their families.
The product was introduced in the United States in 2019, and hundreds of the devices have been fitted through selected O&P facilities, including Hanger Clinic, Shriners Hospitals, and Ability P&O.
The transradial robotic Hero Arm was designed to fit children and adults of all sizes, says Payne, who identifies one of the primary features that make it unique: "People love expressing themselves through their prosthesis; and the high level of adoption that we see comes from the many options available for the wearer to make a fashion statement or reveal their personality just as easily as they change their clothes or their hair color."
The dynamic graphics available on the swappable arm covers include the official Metal Gear Solid Arm, the official Iron Man Arm, plus designs from Deus Ex, Disney, and potentially James Cameron's Alita: Battle Angel. One young wearer in the United Kingdom has built an extensive collection, and changes her arm covers when she changes her outfit—two or three times per day, Payne reports.
The Hero Arm is also exceptionally lightweight, partially due to its ventilated parametric design, with strategic holes in the socket and the liner. For a pediatric patient, it does not need to be replaced as often as a traditional prosthesis because its design, with a flexible liner, includes built-in stretch and growing space so it can be expanded as the child grows.
Shoemaker notes that the Hero Arm's use of completely 3D-printed technology—not accessible two years ago—offers accessibility to high quality and lower cost for a larger portion of the population—children, in particular.
"It's not really an apples-to-apples comparison with the high-end i-Limb hands, but it's functional, it's inexpensive; we've fit a couple of these, and the kids love it."
Nevertheless, Payne still regards the Hero Arm as a work in progress. "We're continually developing the Hero Arm since we thrive on feedback from the community and continually implement changes that improve it," she says.
Education in 3D design and manufacture continues to be a challenge for the O&P profession, Payne says."3D-industry manufacturers, technicians, and engineers are further ahead in terms of technology adoption than clinicians. Many clinicians we train have never seen a 3D printer or used a 3D scanner before and weren't trained on CAD. So they don't know how to manipulate a prosthesis in the digital workflow and aren't familiar with the materials that we're using. There's a big knowledge gap that needs to be filled to move O&P forward to take advantage of what's available."
Hanger Clinic is also making waves with its own cutting-edge advancement— a proprietary 3D-printed passive pediatric upper-limb device currently being delivered to two patients who will be its first beneficiaries.
Development of the device began in mid-2020, reports Antonio Dias, director of engineering, Hanger Fabrication Network, headquartered in Tempe, Arizona.
"The device is designed with a tensioned thumb, which allows our patients to grasp, pinch, and pick up objects as they become more accustomed to wearing a prosthetic device," he says. "3D printing affords the ability to precisely and efficiently print the majority of hardware and components and do so in a way that they are manufactured fully assembled. This allows us to produce a lighter device that can be quickly manufactured and digitally scaled to perfectly fit our patients."
The engineers and designers overcame a number of challenges to achieve this pioneering advancement in prosthetic 3D technology. "Combining mechanical design with an anatomic shape requires a variety of software packages and care when blending the design together," Dias points out. "Additionally, we prioritize safety, which requires testing and engineering reviews to ensure that the device performs exceptionally and safely as expected."
"Hanger Clinic has fit a number of upper-limb patients using this 3D-printed technology, especially adults with partial hand prosthetic needs," says Bryan Lott, CP, Hanger Clinic patient care facility, Durango, Colorado. "The new pediatric-specific design is focused on children with below-elbow limb loss or limb difference who are interested in a passive functional device.
"My patient, Ayden, is six years old, and one of the first children in the US to be fitted with our new 3D-printed prosthetic arm. Ayden was born without his right arm below the elbow, and his last prosthesis was provided to him about a year ago. Because he's six and growing rapidly, we thought he would be a great candidate for a 3D-printed device due to the quick and economical fabrication," Lott says. "The device's light weight and the potential of the finished product to look amazing were also attractive features: It will be completed with hydro dipping, an innovative method of applying designs to 3D-printed devices, painted with a thermochromatic paint that becomes transparent when warmed to 86 degrees Fahrenheit. Ayden got to choose his own design, which features flames."
Ayden's new prosthetic hand is also 3D-printed and is manually operated by his sound side hand. It is fabricated to allow any ½-20 threaded terminal device, so he can interchange other hands or activity-specific terminal devices easily.
Who Benefits from 3D-printed Devices? And How?
At what age can pediatric patients be safely fitted with 3D devices, and is that changing as the technology evolves?
"Generally," says Lott, "we recommend introducing a first upper-limb prosthetic device when a child reaches the developmental milestone of being able to sit, which can happen as early asaround five to six months. The suitable age range hasn't changed with the development of 3D-printed devices. However, the ability for clinicians to provide diagnostic devices, or make indicated adjustments to devices has improved due to benefits of 3D-printing technology.
"At Hanger Clinic," he adds, "we can make changes to upper-extremity socket fit, device length, hand size, or other characteristics on a laptop or iPad screen, with patient and family present. Then we can send the adjustments to our Hanger Fabrication Network team, who will use our HP Multi Jet Fusion 3D-printing technology to print the modified device and have it ready the next day. This timeline is difficult with a traditionally fabricated device."
Shoemaker notes that the age when Ability starts to fit a pediatric prosthesis varies and depends on the child's capabilities and function. "I think that anybody that we would fit with a conventional prosthesis could also be fit with a 3D prosthesis, regardless of their age."
Payne notes that the Hero Arm cannot fit anyone smaller than seven years old—and that the child's size and muscle mass would need to be considered, since the myoelectric device requires adequate electromyography muscle signal strength. "There's not really an upper limit on Hero Arm size. We make them for adults, too—even really, really tall adults," she clarifies.
"Most patients who have a medical necessity for a traditionally fabricated upper-limb prosthetic device could be considered for a 3D-printed device or 3D-printed parts within an overall prosthetic assembly," says Lott.
Like Payne and Shoemaker, he stresses that "much of this success is due to the collaboration between the patient, their clinician, and the design team to custom build a device that meets the patient's needs and helps them achieve their goals."
In conjunction with advances in the 3D-printing process, have materials strengths and durability also improved?
"Some 3D-printing machines can now fabricate 3D-printed devices or parts to easily replace components that break or fail," says Lott. "The materials we use are robust, with a strength-to-weight ratio that rivals traditionally fabricated designs."
Dias also points out that 3D-printing technology has evolved to a point where materials can be printed at similar strength as their injection-molded counterparts. "Hanger has invested in the HP Jet Fusion 4200 3D printer, which has the ability to print nylon-11 and nylon-12. Devices and their components printed with the HP Multi Jet Fusion technology have been strength tested and verified to withstand the functional needs of both pediatric and adult upper-extremity patients. In addition, the printed devices offer an increased level of customization and comfort achieved through design only possible with 3D printing."
Shoemaker agrees. "Kids break everything. So durability is a high priority. But usually durability comes at the expense of weight and bulk. What I think 3D printing can do for us is provide durability without necessarily increasing weight or bulk. They're 3D printing metals and carbon fiber layups, so the materials and the durability exist—but the cost of these high-end printers is going to need to come down before it's accessible to most of us."
It's that high cost that puts bionic technology out of reach for most upper-limb amputee children and families, and it's what motivated Payne to develop the 3D Hero Arm solution.
"The Hero Arm is roughly five times cheaper than other multi-grip bionic hands, and we deliberately designed the Hero Arm to be cost effective," Payne says. "One of the key findings from the community was that multi-grip arms were just too expensive, since most of them range from $30,000 to $50,000."
"As young companies like Open Bionics enter the industry and healthy competition brings the price down, we're going to start seeing some very interesting changes in the industry," she predicts.
Judith Philipps Otto is a freelance writer who has assisted with marketing and public relations for various clients in the O&P profession. She has been a newspaper writer and editor and has won national and international awards as a broadcast writer-producer.