Vets use 3D printing technology to help with double hip replacement surgery for a dog

A Labrador retriever named Ava is back to running and playing with her family after her second double hip replacement, thanks to Texas A&M University veterinarians, computed tomography (CT)-guided planning and 3D printing technology.

When the two replacement hips Ava received as a puppy wore out in 2020, Texas A&M vets were able to remove the old joints and replace them with new ones, using CT-guided planning, 3D-printed bone models and practice surgeries to ensure the procedures would be successful .

From foster family to family

Not many dogs go through four total hip replacements (THRs) in a lifetime, but Ava has always been special.

“Ava came to us at about 6 months old when we were foster parents living in Illinois,” said Ava’s owner, Janet Dieter. “After fostering more than 40 dogs, she was our first ‘foster failure’ that we ended up adopting. At the time, we had another black labrador named Roscoe, who was usually standoffish with the foster pups, but he fell in love with Ava immediately and we knew she had to stay.”

Janet and her husband, Ken, always take the dogs under their care to obedience school, and Ava was no exception. However, it was there that the couple began to notice something different about her.

“The subject of how to stop your dog from jumping on you came up and we realized that Ava never jumps on us,” Janet said. “We took her to our local vet and they took an x-ray which showed Ava’s hips were pretty much out of their sockets.”

Dieters was referred to a skilled total hip replacement surgeon who performed THRs on Ava’s hips in 2013 and 2014.

“She was incredibly resilient,” Janet said. “She walked out of the hospital as if nothing had happened.”

For many years since then, Ava has helped show the Dieters’ foster pups the ropes by giving them someone to play with. When Dieters moved from Illinois to Texas a few years ago, she took the change in stride.

In 2020, however, Ava faced new challenges when one of her replacement hips wore out.

“Over many years, the artificial ball had worn away the plastic lining that protected the metal wall of the artificial joint,” said Dr. Brian Saunders, Professor of Small Animal Orthopedics and Head of Small Animal Orthopedics at the Veterinary Teaching Hospital. “The artificial ball then wore through the metal backing, causing a complete dislocation.”

While worn THRs are not common in dogs, they can occur in joint replacements that have been in place for many years.

“When Ava’s original hips were placed, the lines in the replacement joints were not as advanced as they are today,” Saunders said. “Technology has now improved to where that problem is less likely to occur. Complications like Ava’s are not very common, but when they do occur, they require advanced techniques to achieve a successful outcome.”

In addition to the dislocation, the erosion of the metal wall in Ava’s hip had caused small metal particles to build up around the joint and in her pelvic canal, forming a granuloma.

“A granuloma is basically a sack of soft tissue that’s trying to contain metal debris,” Saunders said. “Ava had a large metal granuloma that was blocking access to the hip joint and affecting her internal organs. There was also a chance that it could cause her body to reject any THR revision implants.

“Metallosis – the erosion process that causes the metal debris to build up into a granuloma – can trigger cellular changes that lead to resorption or dissolution of bone around the new hip. It’s like putting the body into a defensive mode against outside objects,” he said.

Taking the operation to a new dimension

Because of the complexity of the surgery needed to remove the granuloma and fix Ava’s hip, the Dieters’ local veterinarian recommended they visit Texas A&M’s orthopedic specialists.

To ensure the complex surgery would be successful, Saunders used advanced CT-guided surgical planning and 3D printing technology.

“We used computer-aided 3D modeling to determine the size and position of the revision implant,” Saunders said. “Basically, we printed a replica of Ava’s dislocated hip and planned exactly how to perform the revision surgery using the 3D bone models. We actually sterilized the plastic models and used them in the OR to help guide the revision surgery.”

Having 3D printing technology right inside the VMTH is a huge advantage for surgical teams.

“If you don’t have your own 3D printing program, you have to send a CT scan to a third-party company using a fee-for-service process. This can be challenging in terms of turnaround time, and you often lose the ability to be involved in the planning process,” Saunders said.

Having a copy of Ava’s hip was especially helpful given that she had a granuloma that complicated things.

“To avoid a THR rejection, we used the CT scan and worked with the soft tissue surgery group to remove as much of the metal granuloma from the pelvic canal before we came back and did the revision THR. So, when we did the revision, we were in able to finish removing the rest of the granuloma from the other side,” Saunders said. “Planning using 3D models and working with the Soft Tissue team were two major contributing factors to our success.”

Although Ava’s first hip revision went well, her challenges weren’t over yet. A few weeks after the first surgery, Ava’s second THR liner also wore out and dislodged. She had to return to VMTH for a second hip revision.

“Fortunately, the second hip was not quite as affected as her first, and we already had her 3D bone models from the recent surgery, so the second hip revision surgery was more straightforward,” Saunders said.

Now 12 years old, Ava hasn’t let her hip history slow her down.

“She’s still zipping all over the backyard and through our practice field,” Janet said. “She’ll even jump over the couch.”

“When she started showing signs that her first hip was wearing out, we thought it might mean the end and we were devastated,” Ken said. “But the vets at Texas A&M were able to bring her back to life.”