Quick Swap Device Helps Amputees Change Limbs Easily

A device created by engineering students at California Polytechnic State University is making it easier for amputees to quickly remove and replace their prosthetic legs.

Through the Quality of Life Plus (QL+) Club at Cal Poly, third-year mechanical engineering students Greg Orekhov and Zachary Hanze and third-year biomedical engineering student Andre Arguelles created the device, called the Quick Swap, about 2½ years ago for a transtibial amputee to complete an Ironman triathlon.

“She needed a way to switch out different limbs for different sections of the race — running, swimming and biking — easily and without taking the socket off,” Hanze said.

The three students worked on the device during their freshman and sophomore years and last year were approached by Jon Monett, the founder of the QL+ Program at Cal Poly, which sponsors the QL+ Club, to create a similar device for Taylor Morris, a Navy veteran who is a quadruple amputee.

“Essentially, he needed the exact same thing,” Orekhov said. “He has limited mobility and needed an extremely simple way to remove his lower limb prostheses and put a different set on.”

“We needed to change just some of the workings of the device a bit to fit his specific range of mobility,” Hanze said.

Andre Arguelles, Zachary Hanze and Greg Orekhov test the Quick Swap on Taylor Morris, a Navy veteran who wanted to change limbs quickly and increase his daily activity.
Andre Arguelles, Zachary Hanze and Greg Orekhov test the Quick Swap on Taylor Morris, a Navy veteran who wanted to change limbs quickly and increase his daily activity.

Image: Hanze Z.

Different prosthesis, same socket

The main constraint of the project was the Quick Swap device had to maintain the alignment of the prosthetic assembly. “Prosthetists spend a lot of time getting the assembly perfect for every single different individual with their unique needs,” Orekhov said. “We needed to ensure that even when the prosthetic leg is removed, the alignment would not be moved.”

Greg Orekhov
Greg Orekhov
Zachary Hanze
Zachary Hanze
Andre Arguelles
Andre Arguelles

In addition, the device had to be designed to ensure speed in the removal and replacement of the prosthetic legs — for example, replacing a walking leg with a running blade. With the Quick Swap device, “an individual who has use of their arms could probably remove the current prosthetic leg and replace it with a different type in less than 10 seconds,” Orekhov said. “It is a simple, quick single-motion device.”

Typically, it takes about 5 minutes for a multilimb amputee to change a prosthetic leg, including removing the socket and liner, without the Quick Swap mechanism, according to Hanze. “Our device is able to reduce that time to about a maximum of 30 seconds,” he said.

“And that is 30 seconds for a quadruple amputee who has limited mobility, essentially only grasping with his myoelectric arm,” Orekhov said.

The Quick Swap design also allows amputees to use the same socket for all different types of prostheses. “This mechanism permits them to have multiple sets of legs be compatible with the same socket, so it can save money in the long run,” Orekhov said.

Smaller, lighter, less expensive

He, Hanze, and Arguelles have conducted testing of the device in different conditions, including typical gait cycles, walking and running. Using information they gathered from gait testing with the Navy veteran using the device, they plan to test the mechanism to failure. “We are trying to figure out how well the device stands up to our estimates and what we can improve design-wise from here,” Orekhov said.

“Because we are undergraduate students, we are learning all of these topics as we go along; we are taking what we are learning and trying to apply it as best we can to the Quick Swap,” Hanze said.

The students continue to work on the Quick Swap to make the design as seamless and reliable as possible and ensure the prosthetic alignment can tolerate all levels of motion and vibration. They hope to use their testing results to optimize the design, making it smaller, lighter and less expensive. They will officially hand off the project to the QL+ Program at the end of the spring quarter at Cal Poly, and then it may evolve into a senior project.


Improved quality of life

In the end, the students’ goal is to help amputees return to their previous standard of life, which is the ultimate goal of the QL+ Program. The program was established in 2009 by Monett. One of his assignments was running a quick-reaction laboratory for the CIA. Upon retirement, he founded a company focused on cyber security and reverse engineering. He had suggested Cal Poly dedicate one of the labs in its new engineering building to improving the quality of life of those who are wounded in the line of duty. Since then, the program has supported 80 projects in prosthetics, system technology, wheelchairs, products for the blind and smart homes. The program initially involved senior projects for engineering students, but about 2 years ago, the students created the QL+ Club.

“Students get involved in the club and then by the time they reach their senior year, they know whether they want to make a career of this or not,” Monett said.

The club currently has 85 members, who include freshmen, sophomores, juniors and some master’s program students. “About a third came to Cal Poly because of our program,” Monett said.

The QL+ Club is based on the same mission as the program that Monett created, but the students have extended it to the local community. “Our two main goals are to provide the best possible prototypes for our challengers who submit the projects and then also to provide the best engineering experiences that we can within the medical device and tech industries for our members,” Hanze said.

“My initial idea and objective was to help the wounded,” Monett said. “It turned out that the main thrust of the program is changing the careers of students. We have a lot of students who came into Cal Poly thinking they were going down one path and then they did a project for us and decided this is what they want to do for a living.” – by Tina DiMarcantonio

Disclosure: Arguelles, Hanze, Monett and Orekhov report no relevant financial disclosures.

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