When Alberto Rosales’ uncle Ramiro suffered a stroke two years ago, it cost him the movement of the left side of his body.

The ensuing months were brutal with rehabilitation sessions with a physical therapist, weekly trips to the doctor’s office, and the cost and time associated with both. Ramiro’s family has supported him, but it has been undeniably tough. Though Ramiro made some progress, he still is unable to move his left arm or bend his left knee, and therapy sessions remain difficult to even attend, let alone work through.

For Alberto, a junior mechatronics engineering major, the feeling of seeing his uncle in that condition, and the knowledge of the toll it takes on his family to care for Ramiro, inspired him to contribute to research that could help others going through similar rehabilitation struggles.

Rosales and fellow engineering major Juan Ruiz are researching and developing a robotic rehabilitation system under the guidance of Department of Electrical and Computer Engineering Chair Kathleen Meehan. The students have focused their studies exclusively on this project during an intensive three-month research program, part of the Chico STEM Connections Collaborative (CSC2). CSC2 is a campus initiative offering support, resources, and opportunities to the University’s underrepresented students majoring in engineering, computer science, construction management, natural sciences, and agriculture.

Rosales and Ruiz, narrowing their focus to the knee’s anterior cruciate ligament (ACL), aim to design and fabricate a mobile brace that would aid in rehabilitation, both through passive motion (supporting the knee to help recover range of motion) and, more innovative still, through active motion—providing adjustable resistance to help strengthen the area. It would also be able to provide real-time electronic data for a physician to analyze remotely, such as the patient’s pain tolerance at various ranges of flexion, creating an at-home scenario that would remove the need for excess office visits.

Two students sit on a stair, smiling and together holding the robotic knee brace prototype they built.
Mechatronic engineering students Juan Ruiz (right) and Alberto Rosales (left) present their robotic knee brace, the project they’ve been developing during the summer’s CSC2 research.

“Physical therapy is really expensive to do, and most people only do the exercises correctly under supervision,” Meehan said. “A lot of people can’t afford therapy. You have to do your copay every time you go, it’s time out of your day from work, and in order to move more freely, you really do need to exercise every day. This is an idea that gives people independence and lets them take ownership of their rehabilitation and freedom.”

Rosales and Ruiz quickly realized, however, that a solution—one in the form of a portable brace that could replace the current in-bed, continuous passive motion machines—must consider the anatomical intricacies of the knee. No engineering solution they could conceive would be complete, Ruiz said, until they understood the ACL’s mechanics and its reconstruction process.

“In the beginning, we thought it’d be simple: The knee is a hinge, so we make a robotic brace with a hinge,” he said. “But we learned about what people go through when they tear an ACL, and we had to think about the anatomy of the structure, how it’s supposed to move, and what steps it would have to follow when it’s recuperating. We had to think about the biomechanics of it.”

Their first resource for that knowledge was Chico State’s head athletic trainer Scott Barker, who explained the fragile balances in play during an ACL reconstruction and recovery, which typically takes a year to complete.

“One of the primary goals is to restore range of motion—but most of us think about that motion as just the one axis of rotation,” Barker explained. “In actuality, there are three axes in play, and it changes with every degree you move through flexion [knee bent] and extension [leg straight]. There’s rolling, sliding, and spinning occurring on each of those axes, and it occurs in a synchronized, controlled fashion.”

In short: The knee is deceptively complicated, and that’s the main reason a perfect brace doesn’t yet exist. Ruiz and Rosales hope they can get close to creating one, first by understanding the ACL and then by engineering a system that accounts for the ligament’s unique nature. The real area of pioneering in the project, Rosales said, will be the implementation of active motion—resistance to strengthen the knee at various points of flexion and extension that can be adjusted in real-time.

A student-designed prototype of a motorized knee brace lays on the ground.
With a mounted motor powering the support of the lower leg, the students’ robotic prototype re-imagines the role of a brace in knee rehabilitation.

The students will continue refining their project throughout the fall semester, having already fashioned an early prototype using a modified athletic brace with a mounted mechanism, designed to support the knee in various stages of flexion and extension. Because the device must be able to support the full weight of the lower leg, the motor attached to the gear on the brace requires significant power. The primary challenge is in constructing a system powerful enough to support the leg while remaining as compact as possible. A likely model to house that motor, which would power the brace through a cable, would be similar to a backpack or an upper-body harness.

“The scope of what they’re trying to do is huge,” Barker said. “The challenge has always been: How do we build a brace with a hinge design that can simulate how the knee needs to move externally, when the controlling structure is internal? That might be where their robotics knowledge and research makes a big difference.”

Facing the potential to improve physical therapy for everyone with an ACL injury, from athletes to those like Rosales’ uncle Ramiro, the students said their ambitions are to pioneer a new way to think about the rehabilitation process—not just in how a mechanism can help the joint, but also how it can work with the patient’s life during recovery.

“Our hope is that it really helps people at home, and hopefully at a lower cost,” Ruiz said. “We want to innovate in physical therapy and help them recuperate faster. Instead of just using robots and technology for fun, we want to lead the way in getting it to benefit people.”