Amin lost his leg in a traffic accident in India when he was just six years old. His family struggled to find an appropriate prosthetic leg. Eventually Amin was fit by a prosthetist who charged so much money that Amin’s father went into debt. The family’s entire community pooled their funds to pay for the prosthetic limb.

Cost wasn’t the only problem. Amin traveled 15 hours to reach the clinic and the prosthetist spent only 15 minutes fitting him—not nearly enough time. A proper prosthetic fitting usually takes anywhere from a few days to a few weeks with a custom cast and socket made during a multistage process. Additionally, a patient should ideally receive receive at least a few days of training to acclimate to the new limb. Without this attention, Amin’s prosthetic socket was ill-fitting and the prosthetic knee noticeably misaligned—Amin’s gait was awkward and uncomfortable.

Amin’s case is not unusual. Remobilizing amputees with prosthetics in a resource-limited setting is a complex challenge. Nearly 3.3 million amputees need a new prosthetic knee each year, with vehicle-related accidents being the major cause of new amputations. We’ve seen that even where care is available, it can be difficult for people with little money to access such care—clinics tend to be far away from rural communities and are cost-prohibitive to reach.

But more than that, if care is accessible (through loans and days of travel like Amin and his father endured), the quality of care can be sorely lacking. We see a significant trade-off between affordability and performance.

The World Health Organization estimates that only 5 to 15 percent of amputees are able to access care in developing countries, and in many of those cases, the outcomes are often like Amin’s. This translates into about 9.5 million above-knee amputees living in developing countries without access to reliable prosthetics and the mobility they can provide.

At Design Revolution (D-Rev), a non-profit product development company headquartered in San Francisco, Calif., we are working to provide life-changing solutions for people like Amin by developing the ReMotion Knee. Our goal is to provide products that improve people’s health and/or increase their incomes, enabling them to lift themselves out of poverty.

The ReMotion Knee started as a student project at Stanford University in 2008. The JaipurFoot Organization (BMVSS), one of the world’s largest producers and fitters of low-cost prosthetics, sponsored the student team to design a higher-performing knee joint than their existing single-axis knee.

After the students developed prototypes of a low-cost, polycentric knee, BMVSS began fitting it and reported improved gait quality and patient satisfaction. Since then, the JaipurKnee—the first version of the ReMotion Knee—has been locally manufactured in India by BMVSS. Three students continued to work on the project independently and in 2011 merged their nascent company with D-Rev to globally scale production and distribution of the prosthetic knee.

While the polycentric prosthetic knee is not new—the concept has been around for at least 50 years—our goal is to make an affordable, high-quality knee, which can be reliably delivered to clinics that have not had easy access to mobility aids. The retail price for the knee is US$80; a comparable device in the western market ranges from $500 to $10,000. The International Committee of the Red Cross has a knee for about $150, but their device is a single-axis knee, which is less stable than the polycentric design of the ReMotion Knee.

Only 5 to 15 percent of amputees can access reliable prosthetics and care in developing countries.

In the fall of 2013, we launched field trials with the latest version of the ReMotion Knee to refine and finalize the design, and just as importantly, better understand the impact of the knee through data collection. We want to know how it affects an amputee’s life, not just to report to our funders or measure our effectiveness, but also to maintain the feedback loop critical for in- formed iteration and improvement. We see this feedback loop as not only allowing us to create a high-quality user-centric knee, but to best learn how to maximize our impact. For instance, Amin was fit with a JaipurKnee when he was eight years old, two years after being fit with his mis- aligned knee. In terms of impact, we know that the knee is relatively affordable, stable, and fits Amin’s needs, but also that his family remains in significant debt from his first knee.

Creating a survey to assess a person’s quality of life can be challenging. How do we put a number to the struggles and triumphs of people wearing a prosthetic knee?

In tracking amputees and their use of the ReMotion Knee, it became clear getting a fuller representation of people’s lives called for a blend of quantitative and qualitative feedback. We collect quantitative data to objectively assess the efficacy of the medical device using standard mobility tests such as the 10 Meter Walk Test and the Timed Up and Go Test. This data allows us to compare the ReMotion Knee with a patient’s previous device and see if a patient’s mobility is improving over time.

Beyond mobility, amputees have told us that they want independence, respect, and self-reliance—critical components to maximizing impact that mobility metrics alone cannot capture. So we also seek qualitative data, particularly empathetic user feedback. User stories and modifications also provide us with critical contextual data on the product, so that we can better address barriers to its adoption.

Three Generations of ReMotion

For example, early work on the original JaipurKnee showed that social stigma is an overarching issue for many amputees. We saw users customizing their JaipurKnee to reduce any noise it might make and to make the device look more like a natural knee under clothing.

Part of the design challenge for the ReMotion Knee is taking into account everyone in the customer value chain who will interact with and could potentially benefit from the product. That goes beyond the amputee to include the prosthetist who fits and aligns the leg system, the technicians who build and repair the components, community rehabilitation workers who reach out to patients, hospital administrators who are making purchasing decisions, family members who may accompany the amputee to the clinic, and everyone with a stake in the success or failure of remobilizing the amputee and using the device.

The needs of the prosthetist are particularly important. The prosthetists we meet are often overburdened, with more patients needing care than their clinics can provide. Prosthetists have little time to experiment with new products or processes. Ultimately, for the product to get traction and create impact, the knee must work within existing systems for prosthetic fitting and have features that prosthetists are accustomed to. To meet this need, we’ve created a knee with a standard “pyramid adapter” connection, along with adjustable friction, thus giving the prosthetist the ability to dynamically align the knee.

Beyond the fitting process, the knee and other components must reliably reach each prosthetics clinic, no matter where the clinic is located. Some clinics we’ve visited have waited up to eight months to receive orders of pros- thetic components. Scheduling the fitting of a patient can become a waiting game, as clinics wait for missing components to arrive. Some clinics rely on donations of used knee joints from the U.S. and other western markets. The supply of donated parts is unreliable, erratic, and can be costly to an organization’s limited resources, because it requires significant effort to manage and refurbish a wide range of inventory.

Field Trials

In the fall of 2013, we launched field trials to test the latest version of the ReMotion Knee with patients at four clinical sites in India, Indonesia, and Guatemala. (These trials were on-going at press time.) Our assessment tool—the survey that drives these trials—went through a product design process just like the knee itself. We treated our partner clinics as the end-users of this product, mapped process flows, and considered their voice and needs during the survey design process. The steps we took in designing the survey have broad applicability in creating survey instruments for resource-limited settings.

We began by conducting an extensive literature review of existing surveys evaluating prosthetic performance. We had hoped to adopt standard metrics that would allow us to compare the ReMotion Knee to other prosthetic knees on the market. We found, however, that almost all studies of prosthetic performance took place in high-income areas, and those surveys do not address the needs and concerns of patients living in our target markets—those living on less than $4 per day. The majority of prosthetics patients in high-income areas were older diabetic patients, whereas our target end-users are younger and active (the average age of the subjects enrolled so far is 35). Also, the questions and measures were inappropriate contextually. For example, one question asked an amputee about the ease of stepping up onto curbs, which doesn’t make sense in our target regions because curb height can be variable or, in some cases, curbs don’t exist at all.

When asked to rate her satisfaction with her current device, she shook her head and said, “I’m devastated.” The smiling and frowning faces on our Likert scale just did not adequately capture the real life they were designed to represent.

Variability in the capacity across the clinics we partner with is also a challenge. The number of skilled prosthetists and technicians, as well as the administrative capabilities, differs from clinic to clinic. Some clinics are permanent and some temporary. While field trials require rigor and strict control, actual data collection from people requires adaptability and flexibility, so that we can quickly pivot on the ground to efficiently manage a quality process and respond to hurdles.

The survey we developed requires that prosthetists spend at least an extra 30 minutes interviewing each patient, that the clinic set up an area for timed gait-testing, and that clinic administrators add on an additional filing system to maintain patient confidentiality. Our experience is that any product, including user surveys, that doesn’t fit with users’ existing behavior and expectations, will not be adopted. We’ve learned through experience that the quality of the data collected may suffer if we ask the subjects and clinicians to do too much beyond their typical operations.

We worked closely with clinics to translate the survey into local languages. Language, in itself, is an interesting design challenge—there aren’t always lingua franca equivalents for technical medical terms. Our translators worked to interpret appropriate colloquial- isms, and we iterated with individual clinics to best update the material to local norms and phrasing. Most clinics asked that technical and medical jargon remain in English, even if English was not the prosthetists’ first language, resulting in a series of hybrid translations—a lesson consistent with previous experiences we’ve had with technical language across a wide range of geographies. We also adapted some of the contexts of the questions to better fit our patient profile. For example, we eliminated questions about swinging a golf club, hitting a puck with a hockey stick, and throwing a bowling ball.

Once a survey is designed with intention, fit to local context, tested, translated into the appropriate language (or mix of languages), it is a product, but it is still an unused one. In any ethnographic study there is an acute tension between drawing out truth and paying respect to the user. How do we understand a user’s very personal and emotional experience and translate that through a survey into a line on a spreadsheet without diminishing his or her reality? This question gets to a central tension in product development; as personal stories can convey what a gait test cannot.

One of the more emotionally challenging amputees that we met during field trials lost her leg about a year ago in Guatemala. Her immobility made it impossible for her to continue her job as a cook, and she has been struggling with her inability to work ever since. Like many patients, she was emotional throughout the interview process, but when we began to talk about her work history she broke down into tears. One of the Guatemalan clinicians we were working with immediately put the paperwork aside and wrapped her in a hug.

When asked to rate her satisfaction with her current device on a scale of 1 to 10, she just shook her head and said, “I’m devastated.” The smiling and frowning faces on our Likert scale just did not adequately capture the real life they were designed to represent. The story reminds us to acknowledge this tension and ultimately prioritize patient care and respect.

Future Steps

Product integration is a key challenge to achieving scale. Almost all of the clinics D-Rev staff visited have reported problems with consistent delivery of components. Issues range from an inconsistent supply of donated devices to a dizzying array of barriers for importation and customs. In order to achieve scale, we realize that we must remove as many of these barriers as we can to make the ordering and delivery of prosthetic components seamless. Devices need to work with a variety of different prosthetic systems, as different clinics around the world have adopted different systems to fit amputees.

We must also be aware of the different profiles of clinics operating in low-income regions, from “parachute prosthetists” that visit a clinic a few times a year, to large government- run facilities ensnared in red tape. We have seen hospitals that will only order all of their components, tools, and materials from a single company because the approval process for ordering new equipment is so complex. Even if a new device provides better performance at a lower cost, these large institutions will be reluctant to change their entire systems.

Finally, it’s crucial that we realize that every country is different. The same rules, regulations, and hurdles that we face in one country may be completely different in each new country we enter. Thoughtful due diligence, including customer and market research, is required for us to navigate that process.

After we complete field trials for the latest version and incorporate the knowledge gained into the design of the prosthesis, we will begin centrally manufacturing the ReMotion Knee and distributing it to clinics globally. We aim to be on the market by the end of 2014.

As we scale production, we’ll also roll out a large-scale system of impact data collection incorporating the lessons we’ve learned from our field trials. We aim to distill the data to the key aspects of patients and clinics that are most critical for increasing adoptability and improving mobility. We hope this will instigate a new era of impact assessment that includes new methods of data collection, analysis, and learning.

Throughout each phase of designing, delivering, and evaluating the ReMotion Knee, we have been user-obsessed—every person that interacts with the product is critical to remobilizing an amputee. Like links in a chain, if one link breaks, the entire chain comes apart, and the product won’t reach the patients who need it.

This user-obsessed mindset requires us to clearly identify and understand each critical aspect to reliably deliver an effective medical device from importation to impact assessment. Without understanding how the product will reach customers and how to evaluate its effectiveness, the best technology alone can- not provide mobility for amputees in need.


This case study was written by Krista Donaldson, Samuel Hamner, Vinesh Narayan and Nicole Rappin.

Krista, D-Rev’s CEO, has been a Silicon Valley “40 Under 40” winner, and a TEDx and Clinton Global Initiative speaker. She is listed in Fast Company’s Co.Design 50 Designers Shaping the Future, and the Public Interest Design 100. She is a Rainer Arnhold Fellow and a Pop!Tech Social Innovation Fellow.

Samuel is a design engineer at D-Rev and motivated by designing solutions that reduce poverty and improve access to healthcare and education in the developing world. Hamner earned his PhD in mechanical engineering at Stanford University.

Vinesh joined D-Rev's ReMotion as product manager after codesigning a low-cost elbow prosthetic in a Stanford University course on medical device design. Narayan holds a Master's degree in Management Science & Engineering from Stanford University with a concentration in Entrepreneurial Design.

Nicole is the operations manager at D-Rev, focusing on organizational efficiency, and an Impact Associate for the ReMotion Knee. Nicole holds a dual-degree from Carnegie Mellon University in Cross Cultural Communication and Music History & Culture.