Dr. Thomas Wilkinson points to the computed tomography (CT) images of a small dog’s severely deformed leg on his computer’s monitor.
“If you just look at the CT images of this leg, I don’t think you can really appreciate how crooked the bone is,” Wilkinson comments.
He shifts his attention to a 3D model on his desk in the Diagnostic Imaging service at Washington State University’s Veterinary Teaching Hospital. It is an exact replica of the bones in the dog’s leg that he created by feeding CT imaging data into a 3D printer. The technology has been used as a tool in human health care since the 1980s, but it has only recently become more prevalent in veterinary medicine and at the teaching hospital, where Wilkinson is the de-facto 3D printing expert.
“With this model,” he said, “our orthopedic surgeons can plan and even test where they are going to make their cuts and other details of the procedure to repair this leg. This can shorten procedure time and even improve outcomes.”
While he has created models for orthopedic and neurological procedures, he is now working with surgeons at WSU to determine if 3D printing technology can be used to simplify a complicated procedure performed at only a handful of facilities in the country.
Cushing’s disease, also known as pituitary dependent hyperadrenocorticism, is caused by a non-cancerous pituitary tumor that triggers excessive levels of the stress hormone cortisol to be released from the adrenal glands. Left untreated, a pituitary tumor can grow large enough to press on the brain and cause neurological symptoms, such as difficulty walking or seeing, seizures or other conditions.
Dr. Tina Owen, a small animal surgeon at WSU, was one of the first veterinarians in the United States to perform the procedure to remove the tumors, and she and her team are among the few capable of performing the surgery. Despite the expertise and experience at WSU, the procedure, called transsphenoidal surgery, is costly and risky, as it involves accessing and removing the tumor through the palate of a dog or cat’s mouth.
The procedure takes place over two days. First, a localization procedure is needed to pinpoint the exact location of the pituitary tumor. This is done by incising the soft palate of the patient’s mouth to expose the base of the animal’s skull, where a pair of small holes are drilled. The soft palate is closed and then a CT scan of the skull is taken. The scan will show the surgeon where the pituitary gland is in relation to the holes drilled.
Based on that information, the team reopens the palate and removes the pituitary tumor the following day.
It is an intensive procedure that is difficult on the patients, with 8-20% of dogs undergoing the operation dying during surgery or shortly after surgery from complications.
Wilkinson approached Owen about using the 3D printer to create a drill guide using a CT scan of the patient’s skull, removing the need for a localization procedure. That means less stress and time under anesthesia for the animal, as well as possibly reducing the cost.
“I proposed to them why don’t we 3D print a device – or a guide – that will literally show them where the hole needs to be,” Wilkinson said.
Owen was intrigued by the potential.
“Ideally this 3D model will slip right in and kind of hook on landmarks in the skull and there will be a hole right in the middle that will match where we want to drill,” Owen said.
Wilkinson and Owen are working to test the idea, and if successful, the guides could become a powerful tool for use on future patients.
In addition to his work with Owen, Wilkinson has assisted WSU’s neurologic and orthopedic surgeons, who can use the models to get a better visualization of the condition of a limb or skull, determine placement of screws, angles of surgical cuts and even practice procedures ahead of time. They also serve as a teaching tool for students, interns and residents, and in helping explain procedures to clients.
“3D printing holds a lot of promise in veterinary medicine,” WSU veterinary neurologist Dr. Annie Chen-Allen said. “If you are able to plan a surgical procedure ahead of time rather than struggle with a live patient under anesthesia, that is really great and so much better for the animals.”