It is difficult for amputees in developing countries to obtain prostheses due to the high cost of materials, and just as difficult to maintain them, given the demanding environment. But students from Stanford University, Calif., in partnership with D-Rev — a nonprofit firm that develops medical devices to improve the health of lower income patients in international markets — are improving the ReMotion Knee and providing it to low income countries around the world.

“The problem right now in many developing countries is twofold. Most patients have no access to any prosthesis, and even those that do can typically only find unstable, single-axis devices,” Vinesh Narayan, product manager for the ReMotion Knee at D-Rev, told O&P Business News. “Our goal is to develop higher quality devices that are accessible to both clinicians and patients in the developing world. An unstable knee is bad for amputees anywhere, but is even worse for patients walking on uneven roads that aren’t paved. Stability is critical for patients in these environments.”

Development of the knee

Originally called the JaipurKnee, the knee joint was originally developed by a group of Stanford students in 2008. Their goal was to design a stable knee joint that was affordable to clinics that could not afford what was currently on the market. Partnered with the JaipurFoot Organization, the group began fitting patients in India with the knee and then realized that their product could also be beneficial to patients outside of India.

“Our goal in starting the ReMotion project was to expand the availability of high quality and affordable prostheses to clinics around the world,” Narayan said.

Version 3 of the ReMotion Knee features
rounded corners to make it less noticeable
under clothes.

Image: Narayan V

That is when they came into contact with D-Rev and began their new partnership. Now on the third version of the knee joint, the kinematics and polymers used for the ReMotion Knee is still largely based on the four-bar linkage mechanism developed at Stanford. However, guided by feedback provided from amputees fitted with the ReMotion Knee, Narayan and colleagues changed the shape of the joint from a blocky shape to a more rounded shape. The team also switched from machining the knee joint, which was a long, expensive process, to an injection moldable design that provides stability and high quality controls.

“We went out into the field expecting to hear feedback related to the way the knee performed, but nearly all of the feedback was related to making the knee less conspicuous,” Narayan said. “You could see sharp corners sticking out under the patient’s clothing, and it did not look natural. In the newer version we developed rounded, flowing corners to make it less noticeable under clothing.”

Working between D-Rev and JaipurFoot, Narayan said they have fitted more than 4,900 amputees with the ReMotion Knee to date.

“I enjoy the work. It is an accessible way to make a big difference in other people’s lives,” he said. “It takes time for a prosthetist to fit a patient and for the patient to learn to use the device properly, but you can see such a transformative effect when you work with a patient and they take their first few steps. That is empowering.”

Next steps

While the field trial for the third version of the ReMotion Knee is being held at clinics in Indonesia, Guatemala and India, Narayan is also preparing for the market launch, which will be held late next year.

“Improving access to quality prostheses means going beyond the design of the knee and thinking about how to make it affordable, consistent and easily acquired. Our model following market launch next year will include central production with manufacturing in one location, which will let us control quality while keeping costs low through higher volumes and pass those savings on to clinics,” Narayan said. “We’re also working on ways to make it easy for our clinics to order [the ReMotion Knee] without having to deal with complex hurdles or having to manufacture the knees themselves. That takes away from what they do best, which is fitting the patients.” — by Casey Murphy