The first task was to complete the business model canvas which consisted of a hypothesis until validated. This program focused on the first two things that a business must identify: customer segments and the value propositions that the product can provide them.

The next step was to identify people to interview. Potential customers include direct users of the product, payers who pay for the product, and influencers who recommend the product and are involved in making purchase decisions.

We then prepared to deliver an elevator pitch, which is a 30-second speech to convince people to let us interview them. As strangers, we wanted to establish credibility by introducing our affiliation and clearly state our aim to conduct market research rather than to sell a product. We then asked for a small amount of time (10–15 minutes) and told them we would greatly appreciate their responses. Meanwhile, we wanted to appeal to them that we could potentially help solve their problems. If they were contacted by email, we provided similar information in a written format.

Next, we prepared the interview questions. We started by asking how they were injured and the treatment they received. To know their pain points, we asked questions such as “How helpful is the current treatment,” “What has been the most painful time since you got injured,” “What do you dislike the most about being injured,” and “What are the challenges you encounter because of the injury?”. We also asked them to suggest solutions by asking questions like, “If there is anything that could help you, what would it be?”

We needed different sets of interview questions depending on the interviewees. When interviewing professionals, we asked questions like “Where in patient care are you involved?” Similar to our questions for patients, we asked “How could patient care be improved?” Shifting the focus to the flaws of the health system and not to the person himself/herself was useful to avoid professionals becoming defensive about their work.

There are two approaches to recruit interviewees: cold calling and warm calling. Cold calling involves contacting strangers with whom we have no social connection by either telephone, email, or drop-in visit [14]. Warm calling involves contacting someone we know or someone we have been referred to [15]. We were introduced to potential interviewees by mentors and preceding interviewees.

Here, we did not want to talk about our product or technology but instead listen to the interviewees with the assumption that they are experts in their own field and therefore know the problems best. It was also helpful to show interest through body language by maintaining good eye contact. Thus, if there were two interviewers, one would be the main interviewer and the other would take notes. If there was only one interviewer, the interviewee was asked politely if the conversation could be recorded on a cell phone.

The goal is to identify related customer segments and their needs. We transcribed audio recordings or completed the written notes as much as possible. We organized the content into “What we thought,” “What we learned,” and “What we are doing next” and highlighted key findings. Then, we grouped similar interviewees together and tried to generalize their characteristics and needs.

We came up with a few possible business models, and we decided which customer segment to proceed with. Here, we considered not only customer needs but also whether our ability or technology that we have was enough to provide a solution, whether the market size was attractive enough, or whether the model could generate sustainable revenue. Although the selection process could sometimes be subjective, it was still supported with evidence.

Our hypothesis was the weight-bearing function of a knee brace could potentially relieve knee pain. We learned that using a device is believed to be safer than pharmaceuticals and more preferable for pain relief from a doctor's point of view. However, interview results with orthopedic doctors showed that the weight-bearing feature of a knee brace is useful for protecting injured body parts but not particularly for relieving pain. Although the knee brace that corrects faulty alignment and decreases mechanical load on patients' knees can help treat osteoarthritis, the use of knee braces is controversial because they may further weaken the knee muscles. Doctors and chiropractors sometimes prescribe knee braces, but physical therapists do not. Doctors also expressed that patients are concerned about the convenience and aesthetic aspects of wearing a knee brace which corresponds with the finding that patients had concerns using an assistive device outdoor because they did not want to appear like a disabled person.

Both orthopedic doctors and physical therapists agree that strengthening muscles through rehab exercises is the key to relieve chronic pain and to a speedy recovery for certain types of musculoskeletal injuries. We learned that the job of physical therapists is to manage patients' pain and adjust the difficulty of the exercises accordingly. They try to motivate patients during the sessions; however, they have no control over patients at home. The major challenge of physical therapists is that patients miss appointments and do not perform home exercises resulting in a less effective treatment. A chiropractor also faces similar challenges with patients not following instructions at home. From a personal trainer, we learned that exercise can be an alternative to medicine for alleviating pain; however, people do not seek help from a personal trainer because they are not aware that a personal trainer can help them.

Through the interviews, we identified customer segments I and II, formed a new customer segment III, and determined new value propositions (Table 3).

Customer segment I consists of patients with chronic pain from demanding jobs which involve standing or climbing for a long period; patients who engage in high-impact sports such as running, skiing, or mountain climbing and patients with osteoarthritis including war veterans. We found that there is a need for pain relief and rehab exercises in this customer segment.

We learned that customer segment II needs a weight-bearing feature for protection and wants a speedy recovery to return to work or sports, which can be achieved by physical therapy, and wants convenience when using mobility aid devices.

Customer segment III is patients with rheumatoid arthritis and cerebral palsy. We identified that they need a mobility aid device to help them walk naturally and to make walking easier and need regular physical rehabilitation treatment.

For now, we assume that aesthetic is common among all the segments, and we did not find enough information about the needs for customization. Further research is needed to clarify these two value propositions.