February 20, 2018

3-Dimensional Printing in Veterinary Medicine

Used in human medicine for years, this technology is now changing the way veterinarians work and holds great promise for better patient care.
By Don Vaughan
At UC Davis, Dr. Arzi and colleagues recently worked with the College of Engineering to create a protective 3-D printed resin mask, known as Exo-K9, for Loca, a 4-month-old Staffordshire bull terrier. A severe bite by another dog fractured her right zygomatic arch and mandible and extensively damaged her temporomandibular joint. The mask fit Loca’s head perfectly, offering an extra layer of protection as she healed from surgery.

The Auburn University Veterinary Teaching Hospital also has turned to 3-D printing for help with difficult cases. One involved a horse that had been kicked in the face, resulting in a complicated eye fracture. Faculty created a 3-D printed model of the horse’s head to determine which implants to use, among other critical decisions.

The holy grail of veterinary 3-D printing is the modeling of specific body parts for implantation. This is a fascinating area of research, especially on the human side, but high manufacturing costs, problems with rejection, and other issues must be resolved before veterinary surgeons can put it to practical use, experts say. “Custom-shaped implants will likely be part of the future, but we still need to refine [the process] from a biomechanical and biological perspective,” Dr. Arzi said. “It must be more biologically acceptable. Soft tissue is not going to be attached to metal, so we need to understand this much better.”

Evelyn Galban, DVM, DACVIM, clinical assistant professor of neurology and neurosurgery at PennVet, sees an especially bright future for 3-D printing in the treatment of spinal problems in dogs. “A lot of our patients have a spinal malformation in which the vertebrae did not form normally, resulting in instability,” she said. “Many different surgeries can be performed to try to correct that instability, but often we need to find some way to stabilize the spine. With 3-D printing, we should be able to print a stabilizing device that will fit exactly to the abnormal curvature, and pin it into place.”

Student Education
Student education is another area that has benefited greatly from the growing use of 3-D printing in veterinary medicine, instructors say. Rather than relying solely on
A red wolf skull being printed on a Zortrax M300 printer.
textbooks, simulations, and other 2-dimensional materials, students can physically hold and practice on modeled bones and other body parts.

“3-D printing allows me to teach people who are tactile learners or who need that tactile information to be better at their jobs,” said Dr. Galban said. “I can print out whatever piece I want them to understand, and they can hold it in their hands and look at it from every angle. If they break it, we can make a new one.” The result: better, more in-touch doctors. “I think that being able to understand things in a more realistic and 3-dimensional way improves [students’] performance,” she said.

Dr. Dyce agrees. “I think students much prefer having something that looks like a bone in their hands,” he said, as opposed to “plumber’s pipe” sawbones traditionally used for practice. In addition, 3-D models are extremely helpful in custom building surgical solutions for deformities. “For example, we can rehearse total hip replacement and see exactly what size and orientation of implant we may be placing into dogs that have a complex deformity around the pelvis, a spinal anomaly that causes pelvic torsion, or chronic dislocation of the hip,” he said.

According to Christopher Walker, PhD, assistant professor of anatomy at North Carolina State University (NCSU) College of Veterinary Medicine in Raleigh, 3-D models are especially useful from a teaching perspective because they are “durable, replaceable, recyclable, and customizable.”

“In the anatomy lab at NC State, we have a lot of fantastic teaching models, like plastinated organs and wire constructions showing nerves and blood vessels, many of which were made in the late 1980s,” Dr. Walker said. “They are fragile and not easily reproducible, so if something breaks, you have to remake the whole thing or spend a considerable amount of time repairing it. My lab has been 3-D scanning a lot of these older models to create a digital archive. Now, if something breaks, we can simply print it out again.”

Like most veterinary schools, the NCSU College of Veterinary Medicine has “bone boxes” containing complete dog and cat skeletons that students use as learning resources. Because of anatomic variations across breeds, however, the bones are not interchangeable. “If something breaks in one of the bone boxes, you can’t just substitute a bone from another breed, because it’s not going to match,” Dr. Walker said. “So, we just completed scanning a domestic dog skeleton, which can be found on the website morphosource.org, a repository for 3-D anatomic data that is free to access. Now our students can go to this website, download an entire dog skeleton as needed, and study it on their computer or print out specific bones in the library.”

Dr. Walker and colleagues have used 3-D prints for other applications, as well, including an inner ear model that he sectioned from a CT scan and then magnified. “Inner ears are so tiny that they are not something you can easily appreciate in the anatomy lab,” he said. “It’s very difficult to dissect out the inner ear structures; 3-D printing makes the anatomy much more accessible for our students.”

Client Education
Using 3-D models also helps veterinarians educate pet owners, advocates say, especially when explaining a complex case or potential treatment. “Now we can create a 3-D model of their pet and show them what needs to be done,” Dr. Arzi said. “It’s much easier for us to deliver the message and for them to understand what we are going to do or what the limitations are. In some cases, it may help them decide that [a procedure] is not what they want for their pet.”

Adds Dr. Galban: “We want every client with whom we speak to be fully on board with how we’re treating their pet. Most of the time we’re drawing sketches and trying to get them to understand anatomy, which very often they have never been exposed to. However, if we can physically show them via 3-D models what happened to their pet and what we’re going to do for it, it invites them to be part of the treatment discussion, which I think is really important.”

Looking to the Future
Most 3-D printing in veterinary medicine is being done primarily at medical schools, teaching hospitals, and specialty practices such as those with a focus on orthopedics. Few, if any, general practitioners rely on the technology to any significant extent because of its cost, required computer expertise, and limited scope in general practice. However, that could change as the cost of commercial 3-D printers comes down and the next generation of practitioners enters the profession with greater computer knowledge.

“When color flat-panel televisions started gaining traction with consumers in the 1990s, a 40-inch plasma screen display cost tens of thousands of dollars. Now, you can buy a 60-inch LED HDTV that is much higher quality for $500,” Dr. Walker noted. “I think that is what we’re going to see with 3-D printing. The quality is going to be better, the cost is going to go down, and perhaps the speed will also improve. I see all of those things leading to a greater use of the technology in multiple venues."

 
Reference:
  1. Winer JN, Verstraete FJM, Cissell DD, Lucero S, Athanasiou KA, Arzi B. The application of 3-dimensional printing for preoperative planning in oral and maxillofacial surgery in dogs and cats. Vet Surg. 2017;46(7)942-951. doi: 10.1111/vsu.12683


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