Undergrads create custom orthotic for three-legged dog

 

Butch could still move around freely, but over time, the added stress from putting all of his weight on three legs instead of four could lead to injuries. 

 

That’s where a group of mechanical engineering and bioengineering students came in. 

 

A team of nine undergraduate students, formed out of the Biomedical Engineering Society, created a custom orthotic to take some of the pressure off of Butch’s legs.

 

“Dogs put a lot of weight on their front legs so over time that would manifest as injuries in joints,” said Varun Jain, a junior in mechanical engineering. “Our orthotic is a precaution that mitigates that risk of injury over time.”

 

The nature of Butch’s injury meant he had no residual limb that could be used for a prosthetic attachment, so the solution was a two-joint orthotic, added to his remaining front leg, that would take the pressure off of all his legs and prevent long-term injuries. The device looks like a brace, similar to that on a person with an ACL injury.

 

Mechanical engineering junior Alexandra Baumgart said they started by using an Xbox Kinect to scan the dog’s left leg, then 3D printed the scan. 

 

The traditional method of creating an orthotic like this involves putting the limb in a mold and building it based off of the mold. This requires the limb to stay completely still – a difficult task for a dog. 

 

“If you told me to put my arm out and keep it straight I would be able to, but for a dog it’s a lot harder,” said project leader Kevin Brenner, a senior in mechanical engineering. “We dealt with that for a while. We tried all these different orientations to scan his leg and even that was tough. So putting a mold around his leg would have been tough because it really needs to be precise to get an accurate mold.” 

 

From the 3D mesh scan, they segmented the model leg and joined the segments with rubber strips to act as ligaments and tendons. They made the shell of the brace out of carbon fiber sheets held together with epoxy. The team then put aluminum rods along the sides of the dog’s forelimb to support the brace while keeping it light. The orthotic hinges on the side of the elbow and wrist make the orthotic more comfortable. 

 

They also researched injuries common in dogs with three legs to make sure their orthotic focused on the correct joints.

 

The team formed after Brenner presented the idea to the Society in November. After meeting Butch through teammate Johnathan Chang, who volunteers at Vet Med, they started building the orthotic during the spring semester. 

 

When Butch first wore the orthotic, there were some small things that needed to be fixed; some parts were too loose and some were too tight. But since the modifications have been made, Butch has been moving around well. 

 

“We weren’t expecting his motion to be different. The idea was that this would just bear some of the weight but it wouldn’t negatively affect the way he walked,” Brenner said. He added that Butch doesn’t seem to have any interest in eating or licking his new limb, which could be dangerous, as carbon fiber should not be ingested. 

 

Butch and his owner received the orthotic for free, which cost only $150 to produce with the help of donations of different parts. The team also got help cutting the carbon fiber from local company Omni Prosthetics and Orthotics. Two PVC bags were provided by Friddle’s Orthopedic Applicances, orthotic hinges were provided by Higgins Supply Company, Inc., and nylon stockinettes were provided by JMS Plastics. 

 

Usually, prosthetic and orthotic devices can cost upwards of $1,000, but this custom product was unlike anything on the market. 

 

“We didn’t find any two-joint orthotics on the market, so in addition to making an orthotic that was  customized just for Butch, we made something that you couldn’t buy,” said Alexander Hasnain, a freshman in bioengineering. 

 

Despite their success, Brenner said they don’t have any intention of starting a company from the product.

 

“It was really service oriented. We just wanted to build something for someone who couldn’t go out and buy one,” Brenner said. “We did this because we wanted to help animals, and we were all interested in this idea.”

 

Other members of the team included Caroline Blassick, sophomore in bioengineering, Grace Deetjen, senior in bioengineering, Kyla Swain, freshman in bioengineering, Brett Volmert, general studies freshman, and Rachel Walker, senior in bioengineering.