Veterinary Surgery Planning and Training in 3D

Oscar the French bulldog was so agile when he was a puppy that his owners joked that he was part cat. “He’d leap up on the couch and walk across the back,” Julie Van der Feen said.

But when Oscar was four, he started having difficulty jumping. Van der Feen said her veterinarian took x-rays, which revealed that Oscar “had lost the genetic lottery.” The Frenchie had been born with a malformed spine, an inherited problem in pugs, English bulldogs, and other breeds with flat faces and corkscrew tails. The veterinarian warned that the spine’s S-shape could start to squash Oscar’s spinal cord, leading to worsening pain, loss of the use of his hind legs, and incontinence.

To relieve that pressure and prolong his mobility, Oscar needed a complicated and rarely performed surgery. Fortunately, his surgical team was able to practice the tricky operation and make customized implants in advance of Oscar’s operation by using a 3D model of his spine—an approach that Cummings School veterinarians are embracing to improve outcomes for complex procedures.

A short course of anti-inflammatory medication along with daily pain medication relieved Oscar’s symptoms last fall, and he was able to jump again. However, his veterinarian warned that if he started wobbling in his rear limbs, he would need surgery immediately.

When Oscar became unsteady on his feet eight months later, Van der Feen heeded her veterinarian’s advice and rushed him to Cummings Veterinary Medical Center. There, an MRI showed veterinary neurologist Ane Uriarte just how severely Oscar’s vertebrae were affecting his spinal cord.

It is not possible to transform a crooked spine back into a straight one and make things “normal,” according to Uriarte. But she said that surgeons could remove the bones damaging Oscar’s spinal cord. Because removing bone would increase the instability of Oscar’s already-shaky spine, the surgical team also would need to create custom titanium plates to shore up the remaining vertebrae. “We needed to do the surgery straight away because if you wait until a dog cannot walk to treat this condition you cannot reverse that,” Uriarte said. “The surgery stops that progression so the dog doesn’t get any worse.”

The day before Oscar’s surgery, veterinary orthopedic surgeon Mike Karlin cradled a resin replica of Oscar’s tiny spine in his hands. Karlin closely studied the model—which he had created from a CT scan of Oscar’s back using a 3D printer—to decide exactly where he needed to remove bone.

At Cummings School, Karlin is leading the charge to use 3D models printed from patients’ CT scan and MRIs to improve outcomes for complicated procedures, such as Oscar’s. Karlin’s lab at Cummings School acquired six 3D printers with the help of a donation from Stan Kovak, the father of Cummings School Advisor Janet Kovak McClaran, V98.

Depending on the complexity of cases being seen in a given week at the Henry and Lois Foster Hospital for Small Animals, “we may use 3D-printing multiple times in a week or go a few weeks without needing to use it," Karlin said.

“With 3D printing, a lot of your decision making takes place preoperatively,” Karlin said. “You make a plan, execute it on the printed bone, and then check to see if the plan worked. If you are happy, you’re good to go. If not, you adjust the plan and print a second set of bones to test how that works. It saves you time in surgery, and pets spend a lot less time under anesthesia.”

Karlin sawed the harmful pieces of “bone” off the model of Oscar’ spine. He then started shaping a pair of metal plates to align tightly alongside the remaining bones’ twists and turns. Forty-five minutes later—after much measuring, clamping, cutting, more measuring, and strenuous bending—the orthopedist had two tailor-made implants. These were sterilized and ready to stabilize Oscar’s backbone when Karlin headed into surgery with Uriarte the following morning.

Today, four months post-surgery, Van der Feen said Oscar is still walking—and getting stronger through physical therapy at Paws in Motion, a veterinary rehabilitation center run by Cummings School alum Suzanne Starr, V96.

Uriarte said 3D printing is valuable for planning surgeries for complex spinal diseases, as well as for reconstructing the skulls of pets that suffer major head injuries or require surgery on their brains.

3D printing also is a great aid in teaching, Uriarte said. “It helps veterinary students and residents better visualize the anatomy when they can play with a 3D-printed body part in real time while we discuss our approach. Surgeons, of course, know what’s going on from the MRI or CT. But it’s simpler for learners of all types to understand when the problem is right there in their hands.”

Karlin said “the potential applications for 3D printing are endless” when it comes to providing veterinary students with ways to gain surgical and other clinical skills before working with actual patients.

Because different resins can be used to create many different textures, he said it’s possible to print a host of inexpensive teaching models. Students can palpate a resin abdomen to find a “tumor” in an organ, for example, or do a blood draw that feels realistic on a leg mold with an artery in it. Over the 2018-19 school year, Karlin worked with students at Tufts’ School of Engineering to develop a more realistic 3D-printable model for Cummings School students to practice spay surgery on. That teaching tool is now being used at Cummings School in a slightly modified form, Karlin said.

The 3D-printed spay/neuter model does not look as realistic as some intensely lifelike animal models used for medical simulation on the veterinary campus. But that’s fine with Karlin, who said the low cost of creating the model allows more students to get time using one to practice the common surgical procedure. Teaching tools “don’t always have to be fancy looking,” Karlin said. “They just need to reproduce the skill students need to learn.”

Genevieve Rajewski can be reached at genevieve.rajewski@tufts.edu.