Simon Fraser University
Engaging the World

Faculty of Applied Sciences

Team FlexTech; back row, left to right: Nicolas Klaassen, Andrea Manjarres. Front row, left to right: Jack Guo, Lauren Fridman, Jason Fevang.

SFU engineering students devise smart solutions for ACL injuries

October 07, 2019
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By Ariane Madden

When Simon Fraser University engineering student Andrea Manjarres tore the anterior cruciate ligament (ACL) in her knee, the pain was more than physical—it was emotionally devastating. What started as a soccer game with friends forced her to prematurely end a semester of classes to get reconstructive surgery followed by months of physiotherapy. 

And Manjarres is not alone. It’s estimated that 250,000 ACL injuries happen every year in Canada and the U.S.A., and their incidence can be career-ending for collegiate and professional athletes.

That’s why, when tasked to devise a capstone project in the School of Engineering Science two student teams, including Manjarres' own, developed prototypes of technology-based solutions to assist athletes and others who are recovering from an ACL injury.

Team FlexTech (Manjarres with Jason Fevang, Jack Guo, Nicolas Klaassen and former SFU volleyball and javelin athlete Lauren Fridman) developed an electronic knee brace and accompanying app to assist athletes as they recover from the injury. 

“We learned that physiotherapy takes sustained effort and if the patient isn’t doing it right they could risk re-injuring the knee or making an injury worse,” says Fridman. “We wanted to make a device that would give the athlete real-time feedback throughout their recovery process.”

The team’s device detects when the wearer’s knee has landed on a dangerous angle (called valgus collapse) during regular walking or exercise and warns them with a pulsing red light. Then, the brace delivers gentle electronic pulses through a neuromuscular electrical stimulation (NMES) system to initiate a corrective movement. The NMES also helps to prevent muscle atrophy and rebuild the athlete’s subconscious neuro-muscular pathways as they recover. 

Each instance of valgus collapse and NMES is recorded in the phone app for the wearer to track their recovery progress and report to their physiotherapist.

Meanwhile, classmates on the Embrace Technologies team (Nathan Batke, Maria Celkova, Angus Chen, Gary Chung, Harry Draaisma and Peter Xu) were devising their solution. 

Inspired by Celkova’s experience in bouldering and gymnastics, the team sought to create a device that could help encourage an injured athlete to strengthen the muscles surrounding their ACL during recovery. They learned that improving overall leg strength could help the athlete get back to their sport faster.

“The human body is a very complicated machine,” says Draaisma. “We wanted to design a device that could help athletes quantify their recovery process as a sort of motivational tool during physiotherapy.”

Their project compares measurements of the electrical signals in each of the wearer’s limbs using surface electromyography (sEMG). As the athlete recovers, the sEMG readings from the braces are recorded in an app, allowing the wearer to track the strength of their injured limb compared to the healthy limb (known as limb symmetry). Once the strength of their legs is at least 80 per cent symmetrical, the athlete could be cleared to play. 

As part of the project requirements, both teams were challenged to adhere to international engineering standards to ensure the safety of their prototypes and to develop a mock business case for how they might manufacture the product and sell it to a commercial market.  

Although neither team has plans to commercialize their devices, they all agree that they learned valuable lessons about engineering, design and teamwork.

“We learned to use the strengths of our team members to do a great project,” says Fridman. “We were proud of the prototypes we made and each other.”

For five of the teammates—Batke, Chen, Fevang, Klaassen and Xu—the project was their last before graduating this fall, each with a bachelor of applied science. Manjarres has fully recovered from her ACL reconstruction and is looking forward to graduating with her peers next spring.