Nearly one-third of strokes occur in people over the age of 65, and most stroke survivors have associated ambulation problems [1, 2].
In this population, the reduction in muscle mass and muscle strength
frequently reduces their daily activities, confines them to bed, and
reduces the ability to move, thus accelerating the degradation of the
neuromuscular system. Stroke can lead to major impairments related to
functional mobility [3,4,5]
that consequently impacts independence and reduces the quality of life.
Conventional gait therapy for stroke survivors, that is provided by
therapists, can improve gait speed and endurance [6], especially when performed in the sub-acute stage [7].
However, it is demanding and exhausting for therapists and outcomes
depend on the skill of the therapist which may vary a lot depending on
experience and expertise. Devices that reduce this burden like the body
weight support system or robot-assisted gait training devices like the
Lokomat have other issues such as being too expensive and bulky, and may
require superior technical skills to operate and therefore may not
suitable for wide usage [8].
Therefore, in recent years, light and easy-to-operate exoskeletons have
become popular which can help stroke survivors who are unable to stand
independently to regain their ability to stand and walk [9].
Exoskeletons have been in development since at least the 1890′s [10].
In the past several decades, many universities, research institutions
and companies have made great progress in developing
exoskeleton-assisted rehabilitation devices [11, 12].
Based on power source types, exoskeletons can be categorized as active
(powered by the external sources) or passive (self-powered through
elastic components) [13,14,15].
Currently, several lower extremity exoskeletons are in the market that
can assist with gait training in stroke survivors, including
treadmill-based Lokomat [16], LokoHelp [17] and ReoAmbulator [18], and wearable systems such as Ekso GT [19], HAL-5 [20] and ReWalk [21].
They are mainly used for elderly people or patients who have lost
walking ability due to stroke or spinal cord injury, so that they can
walk, sit up, and climb stairs, thus reducing the burden on the
caregiver and improving the quality of life of the patients [22].
Exoskeletal
devices target characteristic deficiencies observed after a
stroke—insufficient forward propulsion, reduced range of motion,
hyper-reflexia which lead to compensatory strategies such as hip hiking,
circumductory gait and elevated metabolic cost [23,24,25,26,27].
Compared with traditional physical therapy, lower extremity
exoskeletons can provide patients with more repeatable and controllable
training, which can reduce the treatment burden of the therapist, so
that the therapist can pay attention to other aspects of the patient’s
treatment [28].
Based on a Cochrane review of electromechanical and robotic-assisted training for walking after stroke [29],
an analysis of 36 different research studies that involved over 1400
participants, it was shown that the use of such devices in combination
with physical therapy can improve walking after stroke. These devices
were shown to be safe and acceptable to most participants. It was noted
that the improvement was greatest for those who were not ambulatory.
Additionally, best results were obtained for treatment in the
acute/sub-acute phase within 3 months of the stroke episode. It is
important to note that a reason for the Cochrane review of this field
was to determine the justification for large equipment and human
resource costs that are needed to implement electromechanical-assisted
gait devices.
Although in the past 20 years, research and
development of robotic exoskeletons has grown rapidly, and many
robotic-assisted systems have been successfully used in scientific
research and clinical applications, the adoption rate remains very low.
According to a survey of 1326 rehabilitation therapists in the US, about
2% of them used some robot-assisted devices for upper and lower
movement rehabilitation [30].
Primary barriers to adoption include the lack of scientific evidence of
effectiveness, high economic costs and low user-friendliness, which
greatly limit clinical usage of robotic exoskeletons [31, 32].
While active devices, like Lokomat, provide several functional benefits
to a variety of patient populations, these are only available to
well-funded clinical facilities and research settings. Moreover, it is
unrealistic for patients to use an active device by themselves because
of its size, weight, cost, and complexity of use. Therefore, there is a
significant need for lighter-weight, easy to wear, user-friendly, and
low-cost technologies for walking training in stroke survivors.
The Kickstart®
Walk Assist system is such a rehabilitation device that consists of a
belt, an external support structure and an Exotendon (Fig. 1).
The effect of the Exotendon is similar to an artificial tendon, which
stores energy during the stance phase and releases it during the swing
phase of the gait cycle. The Exotendon mechanism is inspired by the
anatomical features of the hind limbs of the horse: in the hind limbs of
the horse, several long tendons span multiple joints, and during the
stance phase, the tendons stretch and store energy, and this stored
energy is then used to initiate gait swing and consequently, reduce
muscle exertion [33, 34].
Compared to other robotic lower extremity exoskeleton systems, the
Kickstart walking system is lighter in weight, easier to wear and take
off, and is inexpensive. In a series of case studies (2 stroke survivors
and one spinal cord injury patient), it was shown that the Kickstart
walking system could increase wearers' walking speed and endurance [35].
Unlike more tightly controlled exoskeletal systems like the Lokomat,
the lightweight, spring-loaded Kickstart walking system could allow
easier interaction with the environment that would be more explorative.
The
purpose of this study was to determine the feasibility of using the
Kickstart walking system in a sample of stroke survivors who were in the
subacute and chronic stages of the disease and attending an inpatient
rehabilitation center. Study participants were tested for several
measures with/without the device after experiencing walking with the
exoskeleton over a period of 5 days. Outcome measures included: (a) gait
measures, (b) balance measures and (c) exoskeleton-use feedback
questionnaire. Results from this study will help us to explore if the
technology can offer a new option for encouraging the recovery of
walking ability of stroke patients, optimizing the rehabilitation
treatment strategy, and providing some reference for subsequent related
research.
