Transcript



Gait Training with a Robotic Leg Brace After Stroke

2015

Dr. Pablo Celnik: Hello, and welcome to the Association of Academic Physiatrists podcast, featuring the American Journal of PM&R article, “Gait Training with a Robotic Leg Brace After Stroke: a Randomized Controlled Pilot Study.”

Today’s podcast will include a question-and-answer with author Dr. Joel Stein, Professor and Chair of the Department of Rehabilitation and Regenerative Medicine at Columbia University, New York, and Chief of Rehabilitation Medicine at Cornell Medical College. I am Dr. Pablo Celnik, Professor and Interim Director of the Physical Medicine and Rehabilitation Department at Johns Hopkins University in Baltimore, Maryland, and I will be hosting this 15-minute podcast.

Welcome to the program, Dr. Stein. Let’s get started. So, in recent years, several studies have investigated the potential utilization of robotic therapy to ameliorate motor impairment following stroke. Can you describe the particular focus of this article and where it fits into the larger program of robotic research?

Dr. Joel Stein: This study was designed to examine the use of a unilateral wearable exoskeletal knee brace to see if gait training with that device would be useful. This is a device that had not been previously studied much in this population. And the goal was to gain some understanding of whether it was first of all feasible, and then a sense of the efficacy, understanding that it was a pilot study.

When you think about the broader context of lower limb devices for stroke rehabilitation, there are several strategies that have been employed. One of those is an exoskeletal workstation-type device such as Lokomat robot, in which the person is strapped in and does exercises over a treadmill, typically. And there are several such devices as well as other types of gait trainers.

The other is a wearable system, and there are several bilateral wearable systems that have been developed, some of which are being explored for possible use in the stroke population. We thought, however, since stroke generally causes unilateral weakness, that it would make the most sense to look at a unilateral device rather than a bilateral device. And thus, we selected this device to test.

Dr. Pablo Celnik: Your study looked at the effects of individualized physical therapy using the bionic leg, on gait speed and endurance. The goal was to confirm the ability of chronic stroke patients with hemiparetic gait to use the device, and test the efficacy in a preliminary study on affecting gait speed and endurance. Now, the control group was exposed to group therapy that did not emphasize gait training. So, it was just to control the exposure to physical therapy and the duration of the sessions.

Although the predictions were that bionic leg training was going to improve gait speed and endurance, the study found no clear benefits, or no clear differences, across the groups, or before and after the intervention within the groups. Are you surprised that robotic treatment did not result in clear gait benefits?

Dr. Joel Stein: So, we undertook this study with the expectation that it would provide benefit, although maintaining equipoise – and I think this study shows the importance of equipoise. We were perhaps surprised, but I think there are reasons why, in retrospect, maybe the results are not unexpected. One is a growing body of literature suggesting that more elaborate techniques or nontraditional techniques for gait training stroke survivors, may not have advantages over standard conventional therapy techniques such as over-ground walking.

A good example of this is the LEAPS trial, which was published while this project was underway, which compared partial body-weight-supported treadmill training with more standard physical therapy techniques, and found that the partial body-weight-supported training, or locomotor training as it’s been called, did not provide incremental benefits.

There have also been a series of studies looking at other robotic systems such as the Lokomat in patients with chronic stable stroke deficits, who are ambulatory but whose walking is slow, and those have also failed to show benefit in comparison to conventional physical therapy.

So, as I look at all this literature in the aggregate, while I think the question is not resolved definitively, there is an overall sense that perhaps the best training mechanism we have for ambulatory stroke patients is in fact walking—that the best therapy that we have to try and improve patients’ walking post-stroke may in fact to have them walk more, or perhaps more quickly. And over-ground may actually be the best way of doing that, rather than necessarily using a treadmill or other device. I think that question is not definitively answered, but I think that this study provides a little bit more evidence in that direction.

Dr. Pablo Celnik: So, in other words, what this study did was provide a similar intervention in terms of walking experience, perhaps to a higher – a degree of higher intensity, but that enough, by itself, is not going to make a difference. Is what you’re implying?

Dr. Joel Stein: Well, actually, that’s an interesting point. You know, one of the interesting aspects of robotic training in this context is that the number of steps taken was not as large as you might otherwise achieve simply by having the patient walk. And that’s maybe in contrast to what you usually think of when you think of robotic therapy, particularly for the upper limb, where the goal is to increase the number of repetitions.

In the walking realm, since walking is typically a rhythmic and representative task, anything that requires that you put it on, that you adjust it, that you alter your activity in some sense, actually has the potential to reduce the number of repetitions accomplished during a given period of time. Obviously, there are ways you could try and enhance that; for example, putting someone on a treadmill at a pace that’s faster than their natural walking speed. But I think that in this case, given the fact that the gait velocity was not predetermined by the system, the patients who use this probably walked less per-unit time than they would have walked without the use of the device.

Dr. Pablo Celnik: I see. Now, there’s another interesting finding in your study. Although both groups have some improvements in secondary outcome measures, like the balance and functional profile, the control group had minimal gait training. I mean, gait training was de-emphasized. So, what’s your interpretation of the beneficial effects observed? Are they minor in this control group?

Dr. Joel Stein: So, this is a bit speculative, but one of my observations is that the patients who participated in this study had to get here to participate. Participation in a clinical trial which was based in our medical facility, required that they walk the fairly lengthy halls here, that they negotiate transportation, and that they get out of their apartments. And I believe that that activity—the process of going to and from the visits that we set up for them—may have actually had the greatest therapeutic value.

I think we tend to think of our studies as occurring simply in the clinic—the time spent between when they walk in the door and when they leave. But there are other aspects, particularly when you’re dealing with mobility, that are inherent in study participation, that may have therapeutic benefits. Many stroke survivors are largely housebound and are not as active in the community as they were prior to the stroke, or compared to non-stroke-affected individuals of similar age. So, I think that perhaps if they just come to visit, say hi and go home, they might have also seen a therapeutic benefit simply from the effort of getting here and traveling themselves.

Dr. Pablo Celnik: That’s right. And so, in other words, the – if the physical effect of the robotic intervention is not beyond what it is, just engaging the patient and bringing them to the clinic and having them walk, and so on.

Dr. Joel Stein: Quite possibly, yes.

Dr. Pablo Celnik: Now, based on this study, would you recommend using this device or other robotic therapy interventions for patients with stroke in the chronic phase?

Dr. Joel Stein: I don’t think that our study supports the use of this device in a comparable population of chronic stroke survivors who are already ambulatory. What that leaves unanswered is whether there are other populations who might benefit from this therapy. In particular, are there patients who are non-ambulatory in the chronic phase who might benefit? And that’s something that that we didn’t examine. Or patients who are very marginally ambulatory, who can take a few steps—we didn’t examine that.

And the other very important population that needs to be looked at, are the patients very early after stroke, who are in the process of regaining ambulation. And the question of whether this type of therapy might accelerate that process, remains unknown. So, I think for the patient population that we studied—the ambulatory chronic stroke survivor—I would say that our results do not support use of this device, but there may be other populations where it can be shown to be useful.

Dr. Pablo Celnik: And so, future studies will have to address that.

Dr. Joel Stein: Exactly.

Dr. Pablo Celnik: Those populations. Now, in a similar note – so, from this study and others, showing relatively modest to no clear advantages of robotic therapy over dose-matched regular exercises, what do you think is the current role of robotic therapy in the rehabilitation setting, and where do you see the future of robotic therapy?

Dr. Joel Stein: First of all, one of the distinction here is probably to differentiate between upper limb training and lower limb training. Because the nature of the robotic devices, the nature of the training paradigms, and frankly the nature of the outcomes for most stroke patients, are very different. The majority of stroke patients are able to regain walking ability, perhaps in modified way and at a slower pace. But many stroke survivors fail to restore sufficient upper limb use to actually incorporate it into daily activities. Also, the nature of walking, which is rhythmic and repetitive, is very different than the use of the upper limb.

So, I think the answers to this question really are twofold. I think there’s a lower limb question and an upper limb question. With regard to the lower limb, which is what we studied in this particular study, I think that the evidence base currently doesn’t support routine use of robotic devices, and I’m uncertain whether it will be proven to be useful. I think that’s unknown. We do need to spend some more time and effort defining the target population and determining how we can improve outcomes.

For the upper limb, I think it’s a different story. I think that there is certainly evidence that robots are able to provide greater numbers of repetitions for stroke survivors than might be achieved in a conventional therapy session. So, there is an argument in favor of robots. That said, there are relatively few studies that suggest that robots have greater efficacy than conventional therapy. There was one recently published in Lancet Neurology, looking at the ARMin robot, which has now been commercially developed as the ArmeoPower robot from Hocoma. And I think that that study did suggest some modest benefit of robotic therapy over conventional therapy, and perhaps so will the others over time.

Exceeding the benefits of standard therapy is a high bar, and perhaps we should be looking to robotic therapy as a way of supplementing a portion of conventional therapy in a way that is ultimately more labor-efficient. We haven’t quite achieved that yet. But I think as devices become simpler to use; perhaps more wearable devices are developed, this may be a way of delivering a larger dose of therapy to patients without requiring them to spend more time working one-on-one with a physical therapist or occupational therapist, which is quite costly and labor-intensive.

In terms of the current state of the art, I think an argument can be made for incorporating upper limb robotic therapy as a supplement to conventional therapy. But I don’t think it’s necessarily standard of care yet. And as I said, for the lower limb, I think that we’re not yet at that stage yet.

Dr. Pablo Celnik: Right. Thank you for all these comments, Dr. Stein. I really agree with your appreciation of the state of the art of robotic therapy in terms of, there may be a role; it may not really be beyond and above of what the standard therapy can do. Perhaps it can help with delivering high intensity, like you mention. Perhaps, therefore, it can be used as a supplement to standard therapy.

But there is nothing beyond the ability to deliver high number of repetition for the upper extremity, or perhaps the engagement of a person playing with a sophisticated machine – there’s nothing else beyond those two assets, apparently, that robotic therapy can contribute beyond a standard therapy delivered by a person.

So, on behalf of the Association of Academic Physiatrists, we would like to thank you for listening to this podcast. More information on podcast and the American Journal of PM&R, including the Journal iPad app, can be found on the AAP website at . This concludes today’s program. Thank you.

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