Thirteen out of the sixteen contacted people participated in the study. Reasons for not participating were self-reported lack of sufficient community-based exoskeleton experience (n = 1), and limited time to participate (n = 2). A summary of the characteristics of the thirteen participants is given in Table 1. To ensure confidentiality, codes (P1gender(age), P2gender(age) etc) were used instead of the participant’s names when indicating from whom a quote originated. All participants were experienced exoskeleton users, who completed a clinical training period of approximately eight weeks (+/- 24 training sessions). They all used the ReWalk™ exoskeleton in the home and community setting, the amount of community use ranged from three to more than 100 days). Three participants had purchased their own ReWalk™ exoskeleton through crowdfunding and, thus, had much more community exoskeleton experience. In addition, six participants also had experience with another exoskeleton: the Indego® exoskeleton in a clinical setting (n = 4, +/- 3 years ago) and/or a research exoskeleton (i.e., March or Symbitron) in a lab setting (n = 4, +/- 1.5 years ago). The time between the last community-based exoskeleton use and the interview ranged between one day and four years (median of two years). The duration of the interviews varied between 30 and 90 minutes.
Table 1
Participant characteristics.
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Total (N = 13)
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Sex (male / female)
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7 / 6
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Age (years), median [min - max]
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33 [25–52]
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Time post injury (years), median [min - max]
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8 [2–28]
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Neurological level of SCI (thoracic), median [min - max]
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Th9 [Th4 – L1]
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Classification of SCI level (low (Th7–12) / high (Th1–6))
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7 / 6
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AIS* (A / B)
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12 / 1
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* AIS = American Spinal Injury Association Impairment Scale, Th = Thoracic, L = Lumbar |
Purpose of exoskeleton use
Three future purposes of exoskeleton use were mentioned in the interviews, namely for daily activities, exercise, and social interaction. Table 2 provides an overview of the purposes of use with exemplary citations. The use during daily activities and for exercise was addressed in the interviews of all participants. Most participants wanted to use the future exoskeleton during daily life activities in which they now used the wheelchair, such as grocery shopping or driving a car. One person even expressed that he wanted to do all activities that he was able to before the SCI, such as walking on the beach or running up the stairs. Participants also mentioned that they were interested in using the exoskeleton as an exercise device to stay fit and to stimulate health benefits. Furthermore, the use of the exoskeleton for social interaction (e.g., go to the pub or join in a group chat at a party with bar tables) was mentioned in almost all interviews. Some participants emphasized that for exercise and social interaction you do not need to purchase your own exoskeleton, but could share an exoskeleton with others as well.
Table 2
Purposes of exoskeleton use with exemplary citations.
Daily activities
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“As it is now, I would use the Rewalk for what I call physio sports. However, you would want to use it to do the things you used to be able to do, like getting up, driving a car, you’d put it on in the morning and keep it on all day. Possibly using it in combination with a wheelchair. It’d be nice though if you didn’t need your wheelchair at all.” P10female(52)
” Ultimately, I’d like to be able to, for example, go for a walk on the beach with my daughters, or take them to an amusement park, and go on rides you actually have to go up steps for. Or at least that you can do things that you can't do right now because of that [wheel]chair.” P3male(29)
“Well, what I envision is a kind of exoskeleton that I can put on like a pair of trousers and that I can wear sitting in my wheelchair. So that, whenever I want to, I can get up or climb a flight of stairs, or whatever. […] When I think of that, of what would be possible, a whole new world opens up.” P11male(37)
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Exercise
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“The purpose of walking? Well, for me it’s pushing back the boundaries. Each time, I try to walk further with it. That’s great. First just a short distance, and then each time go a bit farther. Yeah, the goal is to push back the boundaries and see how far you can walk with a suit [= exoskeleton] like this.” P9male(49)
“But I’d like to use it in a rehabilitation centre, for example, to be able to walk. Preferably together with others, so you can learn from each other. For the health benefits, you know. I wouldn’t use it so much for practical things, but more to improve my health, and not have to sit in my chair all day. That I can walk. That there’s pressure on my joints. So that you can keep walking. That’s why I think it’s useful… to improve your health. I’d really like to use it for that.” P2female(44)
“Also for health reasons, of course. Having walked for about three and a half months I felt even fitter. Just bladder and bowel goes easier and, when you walk and move your hips a few times a week, it [your body] feels more comfortable, that sounds a bit weird, but yes that's what happens." P4female(49)
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Social interaction
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” So that you can join in. For instance, I hate parties where they have standing tables. It’d be great to be able to just stand at a table like that. And with a bar stool nearby for support if necessary or to rest a bit, so that basically you don’t stand out from the crowd. Yes, I think that’s something that would make this kind of suit [= exoskeleton] very useful.” P7female(30)
“I didn’t want to think about that for a very long time. I told myself that it wasn’t really important to me. But it’s true that people really like to look at you at eye level. And they suddenly notice you again and say, hey, wow, I haven’t seen you standing up like this before.” P5female(49)
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Motives for exoskeleton use
In addition to the purposes of future exoskeleton use, three motives for exoskeleton use were clearly described in the interviews, namely societal importance, preserving autonomy, and fun. A few participants mentioned that for them, a motivation for exoskeleton use was the societal importance for further development.
P5female(49): “I think it’s something that’s still in its infancy, that needs to be developed further. […]. I think we should all do our bit to make that happen […] it may actually be something that will be covered by health insurance in the future. Mainly for people who’ve recently suffered a spinal cord injury, I should think.”
The use of the exoskeleton was frequently compared to wheelchair use, which is something this population uses on a daily basis. For example, some participants stressed that they are completely autonomous with their wheelchair, and that this level of independence is something they also wanted to pursue with the future exoskeleton, especially during daily activities.
P2female(44): “Independence. I think that's the biggest one. I’m now too dependent on someone else or on devices, for safety, weight, all the things I can’t do myself, over which I’ve no control now. Yes, independence. Not needing help with anything. That’s it basically.”
Contrary to wheelchair use, the motive for exoskeleton use was sometimes referred to as ‘for fun’, in which fun was an end in itself.
P7female(30): “Well.. it has to be fun. That it becomes less therapeutic. Sure, it will never be exactly the walking you were used to [before the injury], but I do think that it’s very close, that you can just go for a nice stroll around the block.”
Improvements of exoskeleton
To optimize the future exoskeleton, different improvements were suggested. Experienced exoskeleton users mentioned that their future exoskeleton is easy to use, small and lightweight, tailor made, safe, comfortable, less distinctive, durable, and affordable (figure 2). The most inner circle (i.e., easy to use) of figure 2 represents the desired improvement that was relevant for all purposes of use, for all participants. The circles further to the edge, represent improvements that are more person-dependent or dependent on the purpose of use. In the next sections, the different suggestions for improvement will be discussed.
First circle: Easy to use
Regardless for which purpose the future exoskeleton will be used, all participants mentioned that the future exoskeleton should be easier to use. Therefore, participants advised to improve the remote-control watch, balance, step and speed adjustments, and donning and doffing of the exoskeleton. Improvements to the remote-control watch were mentioned most frequently, for instance improving readability in sunlight and/or changing control options. Suggested control options were via speech or via touch (e.g., touching the thigh to walk and touching the bottom to sit down). Some participants suggested to relocate the control to the crutches, as long as the crutches are needed for balance support. This crutch-control would preferably include a small screen on which different speeds, step heights and step frequencies could be selected. In addition, participants mentioned that keeping balance with the exoskeleton (especially in stance) required much physical and mental effort. To be able to focus on other things, such as a conversation or use of kitchen utensils, balance improvements in the future exoskeleton were desired.
P11male(37): “What’s essential in that suit [= exoskeleton]? What can still be improved? Well, first of all, the balance. Not having to use crutches anymore is the most important thing. […] That you don’t constantly need to keep your balance; the suit should do that for you. That’s what I think is crucial. Suppose I could walk the way I am doing now, but could keep my balance without needing crutches. That would immediately be a real functional improvement.”
Step and speed adjustments were desired so that the exoskeleton could be used more broadly.
P9male(49): “It should have gears, like in a car. Or let’s take a bike as an example. Let’s say you have one, two, three positions and that the third position is the highest gear. This gear allows you to, for example, take a big step, or increase your pace. That works perfectly for outdoors. Position two would then be something just in between. And position one would reduce the length of your steps and their frequency. Then I think it could be used functionally in a home situation indoors.”
In addition, some participants expressed the wish don and doff the exoskeleton, without needing several preparations: P10female(52): “You also have to bring something [a stool] on which you put it [the exoskeleton], to be able to don it there.” and P6female(29). “I don’t want to spend more time putting it on than that I’m actually using it.”
Second circle: Small, lightweight and tailor made
The improvements in the second circle were mostly related to transporting the exoskeleton and adjusting the hardware to the body of the user. Participants agreed that they could not lift and transport the exoskeleton (in a convenient way) by themselves, due to the weight and the physical dimensions.
P8male(28): “But maybe it will make a difference when carrying it to and from the car. If I can move it myself, for example, in three sections instead of one big awkward lump for which I would need someone else to help me. […] It wouldn’t be so heavy then. Maybe it’ll save some space. That would make me independent. I’d be very happy, even if it did take me five minutes longer to put it on.”
In addition, participants mentioned that, especially due to the crutches, you need a lot of space. Therefore, some participants noted that their (wheelchair friendly) house was too cramped for exoskeleton use. A minority of the participants expressed the desire for an exoskeleton that is exactly tailored to their body, but can also be adjusted to different people, in case you want to share an exoskeleton.
P7female(30): “Normally you have enough space but now it feels mega small, because with that suit [= exoskeleton] and those crutches you’re a bit like a big robot stomping around the house. It’s not very pleasant. I hope that in the future they’ll be able to develop suits that are as compact as possible, so that you can easily use [them] at home. It would be really great if I could do more things standing or walking.”
Third circle: Safe, comfortable and less distinctive
Opinions on improving safety were diverse. Some participants considered the safety of the exoskeleton as very important and even something that – if not guaranteed – would lead to disuse, while others felt that using the exoskeleton was safe and the risks were similar to other activities.
P5female(49) “Improvements that would make me use it regularly to move about? Well, most certainly an emergency stop. […] Suppose getting up doesn’t go well… if you could just press something in your crutches if things start to go wrong, and you’d be able to get back in the right position and slowly lower it, so that you go back to base [the sitting position], if I had had those options I think it would have been less scary for me.”
P4female(49) “In the end there is one thing you don't want and that is falling.”
P9male(49): “Yes, you can fall, but you can also fall over in your wheelchair, you know. There’s no danger of that. Zero, nil, nothing! It may happen that your crutch slips when you’re walking somewhere and that it bounces a bit, but so what? If I go handcycling, another road users may not see me and I may get hit by a car, but that’s a risk I’m willing to take.”
Participants who desired an exoskeleton that could be worn all day, mentioned that it should be comfortable to wear and that, for example, a battery on your back would be inconvenient in order to sit comfortably (anywhere).
P11male(37): “It’s just a hassle with that thing. You’re completely constricted, even when sitting. You can’t really move well in it. So I could sit in the pub in it, but I wouldn’t feel very relaxed.”
Although most participants focused more on the functionality of the exoskeleton, some participants expressed the wish to make the exoskeleton’s appearance as close to normal as possible, so that they don’t attract (extra) attention in public situations (e.g., less visible and less noisy).
P1male(27): “That it [the walking pattern] looks natural. So that people don’t think you’re some kind of robot. I think you could easily do this with the latest software.”
Fourth circle: Affordable and durable
Most participants indicated that the current exoskeletons are too expensive, especially with respect to what it is currently capable of. Therefore, almost all participants focused on improvements to its functionality. However, a minority mentioned that not all improvements were necessary and one participant pointed out that the exoskeleton should have fewer functionalities, so that it could be marketed cheaper and become accessible to a larger group.
P1male(27): “I think you first need to focus on affordability and, of course, functionality, particularly if you want to stimulate further development. After all, it’s a very specific target group.”
In addition, only a few participants mentioned improvements about the durability of the exoskeleton.
P13male(25) “Then [to be able to walk in the rain] you need to make it waterproof. So, for example, the bearings need to be well sealed, and you need to use corrosion-resistant material. Like mobile phones. All mobile phones are water resistant nowadays… So that means a backpack... but that will all drive up the price.”