• Feature

    A New Dimension to Physical Therapy

    PTs and PTAs are exploring the uses and potential of 3D printing in clinical practice.

    3D

    The advent of 3-dimensional (3D) printers in the 1990s led people to dream about what someday could be accomplished, especially in health care. Physical therapists (PTs) were among those with big ideas about what might be possible for their profession. In less than 30 years, many of those concepts are coming to fruition.

    Today, 3D printing is being used to customize assistive devices, modify special equipment, and create specific adaptations for equipment or exercises. In audiology, for example, hearing aids are manufactured almost exclusively using 3D printing.1 And many PTs are finding that using a 3D printer can move a clinic ahead in a competitive environment.

    At its most basic, 3D printing begins with a digital model—a type of computer program. The printer then turns that digital model into a physical object—often but not always mechanical parts—by adding materials layer by layer. (See "What is 3D Printing?" on page 29.)

    Karen Gordes, PT, DScPT, PhD, is an assistant professor in the Department of Physical Therapy and Rehabilitative Sciences at the University of Maryland-Baltimore. She says 3D printing is surging across the entire medical field, taking particularly significant strides in certain arenas. However, she adds, 3D printing in physical therapy is at an early stage. She cites barriers to broader implementation that include viable usage options, marketability, and issues surrounding liability, billing, and coding.

    Gordes has used 3D printing to develop adaptive equipment for underserved patients with complex medical conditions. She explains that items can be molded specifically to the patient for ideal fit and function. Examples include adjusting existing devices to account for contractures and strength limitations.

    "Once a basic mold is scanned, additional alterations can occur via software to further fine-tune the specifications of the product," she says. "Several prototypes of an adaptive piece can be printed at low cost until the fit is just right."

    She sees an especially strong market opportunity in generating adaptive equipment for pediatric patients. "Using 3D printing, one can produce modifications in line with developmental changes at less cost and faster turnaround time than by traditional methods," she says.

    Gordes was 1 of 4 PTs on this year’s APTA Combined Sections Meeting panel titled "Using 3D Printing in Physical Therapy: Competitive Advantage and Improved Care." Also on the panel was Robert Latz, PT, DPT, of Trinity Rehabilitation Services in St Clairsville, Ohio. Latz points out that many patients need individualized modifications to equipment, be it a brace or support, or even a tool that makes their daily life a little easier. PTs traditionally have used splinting materials that have been heated and shaped to the patient’s anatomy. 3D printing is, in essence, a refinement of this process.

    "As printers become faster, more accurate, and able to print with more materials, their use and function become even more important for us as clinicians," Latz says. "Separately, physicians are using 3D printing in several ways—from creating bone scaffolding, to printing skin cells, to printing other body tissues. Some of these practices are in research stages. Even so, in physical therapy, we are seeing patients come in for treatment in which 3D modeling or regenerative processes might have been used."

    For example, a few years ago Latz worked with a patient who’d had a total knee replacement. A 3D image of the patient’s knee had been taken prior to surgery. Sizing of the replacement was determined on the model, and then the surgical process completed. Today, this might be considered routine, but back then the process was just being developed, and Latz found the results impressive.

    He also sees extensive potential for 3D printing involving insoles or shoe orthotics. In the past, he explains, PTs molded the foot shape, then created a hard plastic orthotic before grinding and smoothing the final product. Today, PTs can use a device that produces 3D images of the foot. Those images are converted into a program that can be read by a 3D printer, which then can print an accurate orthotic with smooth edges.

    Outside the clinic, Latz has explored the capabilities of 3D printing with 2 printers he’s personally owned—both desktop varieties that cost him less than $300.

    Many PTs rely on non-PT specialists to deal with the technicalities of 3D design and printing. Drew Aufhammer, a California-based financial analyst, has turned his hobby of 3D printing into a business. He’s been constructing innovative tools for a nearby PT, primarily for use in myofascial release.

    "I worked with the PT to model up his instrument ideas in CAD [computer-aided design] software and then 3D print them so he could test them out. He was quickly able to assess the effectiveness of his designs, and, due to the low cost and quick turnaround of 3D printing, he could rapidly refine his designs to produce an instrument that was extremely effective," Aufhammer says. "The huge advantage of 3D printing here was the ability to quickly iterate designs in a cost-effective way."

    Aufhammer uses 3D printing as a rapid prototyping tool, according to an interview he gave for a YouTube program.2 In that program, the PT determines that the cost to produce 2 tools using injection molding could be $6,000. So, he provides Aufhammer with the information needed to design the tools on a computer. Aufhammer produces the tools using 3D printing, then uses the printed tools to make a silicone mold to produce small quantities of the tool. The PT tests the tools and makes appropriate tweaks.

    Aufhammer comments on the video: "To get injection molding tooling for his tools would be a pretty costly investment at this stage, especially as he’s continually changing and iterating these designs. It wouldn’t worth it at this point to do [injection molding right now]."

    Speaking of 3D printing in general, Aufhammer says its 2 major advantages for PTs over other manufacturing techniques are the ability to make items that are customized to the patient (such as prostheses, implants, assistive devices, braces, and splints) and the ability to more quickly develop specialized instruments by reducing research and development costs and time.

    Jessica Pepper, PTA, who works at Team Rehabilitation Physical Therapy in Livonia, Michigan, has a strong background in computer modeling and rapid prototyping. She believes that barriers to greater 3D printing use by PTs and physical therapist assistants (PTAs) include the cost of a 3D scanner, users’ knowledge and computer skills, and software needed to convert that scan to a printable 3D model.

    Still, she thinks it’s an investment worth making, in terms of both time and money.

    "Just about anything you can think of can be created using a 3D printer, as long as the part is thick enough to support its own weight," Pepper says. "It could be used for making a piece of an ankle-foot orthosis [AFO] that has broken off. Or, you could make the whole AFO based on the amount of pressure in the foot and a scan of the foot."

    Jon Mehlferber, PhD, MFA, a professor of visual arts at the University of North Georgia who heads the university’s 3D printing efforts, says a growing number of PTs are recognizing 3D printing as a valuable tool to help them practice more effectively.

    "In 2014, I began working with faculty and students in our PT department to develop 3D-printed assistive devices for children with severe disabilities," he says. "We came up with solutions that include what could be described as hand braces and foot braces. These were customized based on 3D scans of the children and were printed overnight. Using this technology, we were able to create devices similar to those made traditionally by an orthotist."

    Made in the traditional way, those 4 custom devices would have taken 6 weeks to produce, at a cost of $8,000, Mehlferber says. By using 3D scanning and printing, the department was able to produce them in 24 hours, at a material cost of $20.

    "When we started, we were more limited by what materials were available and by the scale of the objects we could make," Mehlferber says. "Now, many more materials are available, and larger-scale prints can be made at a reasonable cost."

    Andrew C. Dragunas, PT, DPT, who works in the department of biomedical engineering and physical therapy at Northwestern University, also is a mechanical engineer, and he has been using 3D printers for several years.

    "I would say the relationship between physical therapy and 3D printing is in its infancy," he says. "A 3D printer is certainly not a common tool that you’d see in every clinic, but I am sure a few are embedded in PT clinics around the country. For the most part, the skills and experience needed to operate a 3D printer fit more into the realm of engineers, fabricators, and prosthetists and orthotists than they do with your typically trained PT."

    Dragunas has been using 3D printing for custom assistive devices, prostheses, and orthoses. But he’s also produced anatomical models for use in patient education. And he’s helped PTs design their own instrument-assisted soft-tissue tools.

    "I’ve printed finger splints and flexible finger prostheses," he says. "I’ve printed anatomical models of the knee joint for potential use in teaching. I’ve used Microsoft Kinect to take 3D scans of my classmates and have printed out 3D busts for their desks."

    Challenges

    Like most technologies, 3D printing capabilities advance constantly. Also like most technologies, just because something can be done doesn’t mean it’s easy. There’s a learning curve associated with the technology.

    "Manufacturing a 3D-printed product that is safe, reliable, durable, and purposeful for a patient is an advanced skill that requires an investment in training and production time," Gordes says.

    Latz offers this scenario: "We might be able to 3D-print a brace or splint for an individual and give it to him today. However, if the patient does not return for us to check for future swelling or potential skin damage from the splint—or weakness in the materials—we might be better off choosing a more researched process for creating the splint."

    He also raises a concern not directly related to patient management. A PT technically might be able to print 25 ski-shaped tips for walkers and offer them for sale to patients. However, Latz warns, in that scenario, the Centers for Medicare and Medicaid Services could question whether the practice now is acting as a durable medical equipment provider rather than as a PT. And that could lead to complications. As APTA explains: "There are many regulations governing the supply of DMEPOS [durable medical equipment, prosthetics, orthotics, and supplies] items for Medicare beneficiaries. Physical therapists should understand how supplier enrollment, accreditation, and competitive bidding impact their ability to provide these items to their patients."3

    Latz adds that 3D printers are a cutting-edge technology and, as such, may face legal challenges—or encounter liability issues related to items that are "printed." Therefore, he says, a clinic should have policies and processes in place related to using a 3D printer and to the distribution of any device or tool printed in a clinic.

    "We do not want to limit innovation, but we do want to encourage PTs and PTAs to protect themselves as much as possible," he says. "Learn, become aware, and prepare for success for yourself and the patients with whom you have the opportunity to work."

    Material Improvements

    New technologies are allowing—and will continue to allow—a greater variety of materials—a growing range of plastics and metals—to be printed.

    "The ability to produce 1-off parts is a huge advantage of 3D printing," Aufhammer says. "This was fairly cost-prohibitive with traditional manufacturing methods. Now parts can be easily customized to the end user and printed on demand."

    For example, a PT now can print a cane handle customized to an individual patient—though Latz notes that this is just an extension of what PTs have been doing. "PTs have been creating individualized cane handles for many, many years," he says. "Sometimes the handles are modified for the effects of rheumatoid arthritis. Sometimes they have incorporated a splint to support the joints. This same process can be replicated with a 3D printer instead of the thermoplastic sheet material we used in the past."

    He adds, "We need to learn and understand the development process a bit further so we know how to make them safer and more functional. This is true for any device we choose to print, whether it’s a brace, support, tool, or cane handle. So when we talk about learning and understanding the development process, PTs and PTAs can benefit from learning more about the types of printers, the types of materials that can be printed, and the process of 3D scanning—all of which can help maximize the individualization possible with 3D printers."

    Latz explains that a PT could use an inexpensive desktop printer to quickly make a prototype. However, this proto-type might or might not be as solid or safe as an actual, refined, finished product would be.

    "On the other hand," Latz adds, "we might choose to jump into the possibilities and purchase a $50,000 or $100,000 unit that can print multiple materials in very high resolution at very high speeds. In this scenario, maybe we choose to print a carbon fiber or metal-based splint. In this instance, we could print a safe splint or brace that’s very individualized and could be printed while patients wait."

    Gordes says there are many issues to consider, such as printer size, material selection, and the size of the product to be printed. All those factors influence how long it takes for something to print.

    "Some objects can take hours to days to print," she notes. "In those instances, it would be unrealistic for a patient to wait at a clinic for the product."

    Mehlferber emphasizes the value of 3D printing’s ability to make devices that are custom-fitted to an individ-ual patient.

    "The more customized the assistive device, the more comfortable it will be, and the more likely the patient will use it regularly," he says. "There definitely is a relationship between ergonomics and safety. For example, left-handed people are more likely to experience accidents and injuries because they live in a right-handed world—from the design of scissors to the location and orientation of doorknobs, and the direction in which doors swing open or closed."

    Including 3D Printing In Physical Therapy Education

    When Latz was enrolled in the University of Montana’s PT education program more than 30 years ago, he learned how to make individualized thermoplastic splints. He even had an extra class on the weekend, during which a thermoplastic supplier brought in sheets for the students to practice with. During that class, students talked about adding rubber bands, clips, and stabilizer loops to the splints that were created.

    He believes this same development process—centered on 3D printing—should be happening within doctor of physical therapy (DPT) programs.

    "We need to learn the technology and apply the development process to this new technology," he says. "If we do not do this, someone else will. I guarantee that the technology of 3D printing is only going to continue to improve and that the cost to create with this technology will continue to decrease. We need to educate our DPT students on how they might consider using these printers to improve care, based on critical evaluation of the needs and goals of the patient."

    Mehlferber, too, believes it is essential for DPT programs to introduce their students to this technology. "Every year that goes by without students learning about 3D scanning and printing will make them less able to be effective and competitive practitioners in their field," he says.

    Pepper, who is enrolled in a DPT program, agrees that she and other PT students should be educated about the possibilities and the technology underlying 3D printing.

    However, she adds that the DPT program isn’t a computer modeling or engineering program, and students aren’t programmers, so to be implemented in the clinic the process needs to be user friendly. "For example," she says, "you might develop a program that could apply patient measurements to premade models."

    Based on the experiences Gordes has had with 2 classes that participated in a 3D-printing pilot program, she says students should be exposed to 3D printing technology but should not be required to demonstrate competence. "There is a significant learning curve to using 3D printing resources for health care needs," she admits. "This may be an area for specialty practice and less of a requirement for graduating generalists."

    Setting a Clinic Apart

    For a PT or PTA who has an interest in the technology and learns how to use the device, a 3D printer can distinguish a clinic from its competitors. Gordes sees a marketing opportunity for clinics to set themselves apart using 3D printing. However, she cautions the practice first to thoroughly assess how the new technology will be incorporated.

    The printers could be used for more than building devices used for treatments. For instance, Latz has discussed the possibility of setting up a 3D printer in the reception area of a clinic and printing appointment chips as a visit reminder for the patient.

    "One side would have our logo and the other their name. Then we could use a marker to write the date and time on a second chip, which previously had been printed," he says. "The idea would be to use this as a way to let patients know we are ready to individualize their treatment as needed—even to the extent of making a special tool for them. This might be a tangible way to remind folks that we provide individualized care and that we balance technology and hands-on care."

    Initially, the ability to produce economical assistive devices could offer a practice a significant competitive advantage. But as time passes, those interviewed for this article predict that the technology will become common practice, and the competitive edge will fade. In fact, patients could in time expect such technology, and facilities that don’t offer it will be at a disadvantage.

    Looking Ahead

    Pepper says incorporating 3D printing into physical therapy initially would be helpful for quick fixes and perhaps for splinting. But she doesn’t think PTs and PTAs understand the technology well enough yet. Still, she believes its adoption will happen quickly.

    Latz says, "There will come a day, I believe, when every office and every PT clinic will have a very good 3D printer available and in constant use." He notes that the first laser printer was sold in 1969, and the first iPhone was sold in 2007—the same year the market first saw a 3D printer system available for under $10,000. Latz’s point: Given where the iPhone is today, it can happen quickly.

    Keith Loria is a freelance writer.

    References

    1. What is 3D printing? The definitive guide. 3D Hubs. https://www.3dhubs.com/guides/3d-printing/. Accessed June 25, 2019.
    2. MatterHackers Minute: 3D Printing Physical Therapy Tools. https://youtu.be/nxqDoEih83c. Accessed June 23, 2019.
    3. Durable Medical Equipment, Prosthetic, Orthotic, & Supplies (DMEPOS). American Physical Therapy Association. http://www.apta.org/Payment/Medicare/DMEPOS/. Accessed June 29, 2019.

    What Is 3D Printing?

    3D printing takes a digital model—a computerized blueprint of the physical object—and turns it into a physical 3-dimensional object by adding material a layer at a time.

    The digital model is created using CAD (computer-aided design) software. Someone using a printer can design a 3D-printable model using CAD software or, frequently, find a model in a rapidly growing online repository.

    As a guide from the company 3D Hubs describes the actual function, "The way a 3D printer works varies by process. For example, desktop FDM (fused deposition modeling) printers melt plastic filaments and lay it down onto the print platform through a nozzle (like a high-precision, computer-controlled glue gun)." That’s the most common 3D printing process; other techniques spray material on a surface, use lasers to melt and fuse powder particles, or bond and laminate sheets of material.

    Depending on the size of the item and the type of printer, printing usually takes about 4 to 18 hours.

    3D printing materials described in this article consist of either plastics—more common—or metals. Among the plastics are polylactic acid (low-cost and good for nonfunctional prototyping), acrylonitrile butadiene styrene, resin, nylon, polyetherimide (an engineering thermoplastic), and thermoplastic polyurethane (which has a rubber-like feel).

    Among the metals used in 3D printing are stainless steel, aluminum, and titanium.

    References

    1. 3D Printed Physical Therapy Tools. MatterHackers. https://www.matterhackers.com/articles/3d-printing-and-mold-making-in-physical-therapy.
    2. Empowering Physical Therapist to Create 3D Printed Assistive Technology. https://www.academia.edu/26564194/Empowering_Physical_Therapist_to_Create_3D_Printed_Assistive_Technology.
    3. Using 3D Printing in Physical Therapy: Competitive Advantage and Improved Care. Handout. 2019 APTA Combined Sections Meeting.
    4. What is 3D printing? The definitive guide. 3D Hubs. https://www.3dhubs.com/guides/3d-printing/.

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