Engineering a healthier future for dogs

Biomedical engineering student uses 3D printing to create a full limb canine prosthesis

Rex, a Bernese Mountain Dog/Cavalier King Charles Spaniel mix.

Meet Rex, whose right front leg was amputated due to a birth deformity.

A 3D visual of the fiberglass cast that was designed to be used as a harness on the dog's torso, attaching the prosthetic. 

“We typically rely on animals as part of our quest to improve human health, but this project flips that model around and we use what we know about humans to help our pets. ”
Albert Titus, Professor and Chair
Department of Biomedical Engineering

By Nicole Capozziello

Biomedical engineering student Sibi Ramachandran is about to see his patient. He’s come prepared with plenty of treats and knows that Rex, an energetic four-year-old Bernese Mountain Dog/Cavalier King Charles Spaniel mix, will likely want a pet between the ears as well.

Ramachandran, a Buffalo-area native who graduated with his master’s degree in May of 2021, thrives on creating unique solutions to help others stand on their two feet—or in this case four. Inspired by his deep love and connection to animals, Ramachandran worked with Filip Stefanovic, a teaching assistant professor of biomedical engineering, on a project that focused on helping a small but distinct subset of dogs: tripods (also called tripawds), or dogs with one missing limb.

While there aren’t statistics on how many of America’s 63 million dog-owning households include a tripod, it is by no means unheard of.

“I’ve seen many tripod dogs over the years, but it wasn’t until my dog Nodin tore his cruciate ligament and needed surgery that I really started to be cognizant of dogs with disabilities, particularly those that are missing limbs,” says Ramachandran. “I started thinking of the idea as a concept from that point, around 10th grade onwards, but didn’t know how I’d go about actually making what was in my head. This project was a great opportunity to turn my dream into reality.”

Guided by his brother Uvun, who was in veterinary school at the time, Ramachandran conceived of a project that utilized 3D printing technology to create a prosthesis for a tripod that was durable, comfortable and reproducible.

Dogs may become tripods for a variety of reasons, from genetic deformities at birth to accidents to diseases like bone cancer. While Ramachandran says that most tripods, particularly ones with full limb amputations, function well without a prosthetic, even the most well-adjusted dog is likely to have issues down the road. The change to their gait and the cumulative effect of their other limbs compensating makes them more likely to develop spinal problems and arthritic joints than their four-legged counterparts. Ultimately, this leads to a decreased quality of life and shorter lifespan for an otherwise healthy dog.

Rex the dog being measured by his spine, torso, and legs and Rex the dog being measured by his legs and paw width.

Rex is measured to fit the harness and pylon.

Using 3D Printing to Help Our Pets

Ramachandran began by advertising his project at UB, Pine Woods Animal Hospital and online. He drew 51 respondents from across the country, and through a lengthy selection process, decided on Rex, of Depew, New York, owned by Michelle and Andrew Dudzinski. Rex was a tripod when the Dudzinskis rescued him; a congenital limb deformity at birth led to his front right limb being removed by surgery early in life.

“Rex is an amazing dog. He listens well, he’s up for anything, he loves people. So, knowing he could have issues down the road, we just want to give him as happy and healthy of a life as possible,” says Andrew Dudzinski. “And Rex was a champ through the whole process.”

Animal patients in need of a prosthetic device face many of the same challenges as humans. First, there’s cost: due in part to the high price of materials, prosthetics are expensive. And, an effective prosthetic must be highly customized. The process of casting, molding and manufacturing is time-consuming and there is no guarantee that the end product will be an excellent fit for the patient. Dog patients face additional challenges, such as a limited number of companies making devices and that the prosthesis needs to fit not only the dog’s body but also its temperament.

3D printing technology, however, provides a potential, underexplored solution. So, thought Ramachandran, why not apply this technology to the veterinary field?  “3D printed systems are much easier to manufacture than traditional prosthetics and as a result, they have the potential to be more affordable to more people,” says Stefanovic. “Typically, I develop these systems for humans, but when Sibi approached me and said he was looking to do this kind of work on animals, it presented a unique opportunity.”

“This is an excellent example of how our students and faculty make a real-world impact,” says Albert Titus, professor and chair of the Department of Biomedical Engineering. “What’s so interesting about Sibi’s work is that we typically rely on animals as part of our quest to improve human health, but this project flips that model around and we use what we know about humans to help our pets. And, we can even use this to learn how to create better prosthetics for humans.”

Creating the Prosthetic Device

First, Ramachandran met with Rex, getting the measurements necessary for the initial step: making a fiberglass cast that would be used as a harness on the dog’s torso, attaching to the prosthetic. Then, Ramachandran created a 3D scan of the cast, which he was able edit and improve digitally.

The second component of this kind of prosthesis is a pylon, which acts as the substitute shin, providing the weight bearing, shock-absorbing shaft for the prosthesis. In this case, Ramachandran designed the pylon and foot as one piece, with a rocking design for the “foot.”

Finally, he used 3D printing to bring his designs to life.

“I had minimal experience with 3D printing prior to this project so the learning curve was extreme, exacerbated by the pandemic,” says Ramachandran. “Although a prosthesis is easily reproducible when the sizing is correct, the iterations to get there can take a really long time due to print times—a day or two per iteration not including post-processing like sanding and adding the liner/cushion.”

However, with a lot of support and on the fly problem-solving, Ramachandran met the challenges that came his way. For instance, after several failed attempts to scan the fiberglass cast of Rex’s torso as one piece, he eventually scanned each half of the cast separately and combined them using Meshmixer software.

Dog wearing a prosthetic limb.

Rex learns to use the prototype.

Testing out the Prototype

Six months after they began working together, Ramachandran was finally able to test the design out on Rex. Fitting the prosthetic was one part while training Rex to use the prosthesis was another process.

Because he’d been a tripod for his whole adult life, Rex had to unlearn some habits, like placing his remaining front limb inwards to stabilize his gait. Training took place gradually over a period of six weeks, beginning with getting Rex used to the weight and feel of the harness before adding the pylon attachment.

Ramachandran used the SMART Motion Lab at UB’s North Campus to record and analyze the implementation phase using motion capture experiments over a period of four weeks.

“It was a long process but it went well, and Sibi was great throughout,” says Dudzinski. “It was fun for Michelle and I to visit UB and see the technology, which was honestly incredible.” And, he adds, Rex really enjoyed his visits to campus as well.

“I can’t praise Sibi enough for his passion and motivation on this project,” says Stefanovic. “He not only did a lot of great engineering work, but also contributed significantly to the community.”

Ramachandran learned a lot from the process and already has ideas for how to improve future designs. His main idea revolves around using thermoplastics for the foot portion, which soften when heated and harden when cooled, allowing them to be both flexible and durable. Because thermoplastics are not currently a 3D printable material, this part of the design would have to be manufactured separately and attached to the 3D printed pylon.

Unfortunately, regardless of material, a custom 3D printed prosthesis is not currently a reality for all animals or humans

in need. Barriers include cost and access to the technology—not everyone is lucky enough to have state-of-the-art labs at their disposal. And as Ramachandran found out, working with 3D printing technology, which is ever-evolving, presents its own challenges. However, propelled by his love of animals and commitment to partnering with others, Ramachandran hopes to keep fine-tuning his idea.

“I really like working with animals and, even though this was a first functional prototype, there were several instances where I saw the prosthesis working as it should and I could see the direction this project could take in the future if further iterations are explored,” says Ramachandran.