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Gait Rehabilitation with Exoskeletons

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The exoskeleton is a robotics-assisted, powered device that enables paralyzed patients to stand up and walk. This chapter examines the state of art concerning the use of active, powered, and wearable lower limb exoskeletons for aiding and rehabilitating paraplegic patients’ gait disorders resulting from serious central nervous system lesions. A qualitative analysis of the literature review found that the rehabilitative use of an exoskeleton is safe and practical, not physically exhausting, and requires just a little cognitive effort. In addition, exoskeleton use is easy to learn, increases mobility and functional abilities, and decreases the risk of secondary injuries, restoring a gait pattern comparable to normal when walking over ground. Nevertheless, the rehabilitative use of an exoskeleton has some important limitations: the wearability criteria are too restrictive, the training to use it autonomously at home is very complex, and the device is still extremely expensive. A further limitation is the scarcity of experimental designs that demonstrate the effectiveness of the exoskeleton compared to other rehabilitative techniques and technologies.
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Gait Rehabilitation with Exoskeletons
Stefano Federici, Fabio Meloni, and Marco Bracalenti
Contents
State of the Art .................................................................................... 2
ExoskeletonsDevelopment and Technical Data ... . .. .. .. .. .. .. .. .............................. 3
Development .. . . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. 3
Technical Data ................................................................................. 5
The Effectiveness of Powered, Active Lower Limb Exoskeletons in Gait Rehabilitation ..... 8
Conclusions ....................................................................................... 32
Cross-References .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 33
References .. . .. .. .. .. .. .. .. .. .. .. .. .. .... . .. .. .. .. .. .. .. .. .. .... . .. .. .. .. .. .. .. .. .. .. .. .... . .. .. .. 34
Abstract
The exoskeleton is a robotics-assisted, powered device that enables paralyzed
patients to stand up and walk. This chapter examines the state of art concerning
the use of active, powered, and wearable lower limb exoskeletons for aiding and
rehabilitating paraplegic patientsgait disorders resulting from serious central
nervous system lesions. A qualitative analysis of the literature review found that
the rehabilitative use of an exoskeleton is safe and practical, not physically
exhausting, and requires just a little cognitive effort. In addition, exoskeleton
use is easy to learn, increases mobility and functional abilities, and decreases the
risk of secondary injuries, restoring a gait pattern comparable to normal when
walking over ground. Nevertheless, the rehabilitative use of an exoskeleton has
some important limitations: the wearability criteria are too restrictive, the training
to use it autonomously at home is very complex, and the device is still extremely
expensive. A further limitation is the scarcity of experimental designs that
S. Federici (*)F. Meloni M. Bracalenti
Department of Philosophy, Social & Human Sciences and Education, University of Perugia,
Perugia, Italy
e-mail: stefano.federici@unipg.it;stefano.federici@gmail.com;fa.meloni@gmail.com;marco.
bracalenti90@gmail.com
#Springer International Publishing AG 2016
B. Müller, S.I. Wolf (eds.), Handbook of Human Motion,
DOI 10.1007/978-3-319-30808-1_80-1
1
demonstrate the effectiveness of the exoskeleton compared to other rehabilitative
techniques and technologies.
Keywords
Powered active lower limb exoskeleton Paraplegic patients Gait disorders
Central nervous system lesions Gait rehabilitation
State of the Art
Gait disorders, classied in ICD-10 as abnormalities of gait and mobility(code
R26), involve a reduction in autonomy and in the ability to move independently. Gait
disorders can result from serious central nervous system (CNS) lesions due to, for
example, spinal cord injury (SCI), cerebrovascular accident (CVA), cerebral palsy,
and infectious diseases (Dickstein et al. 2014; Lee et al. 2014). Usually, the patient is
forced to rely on a wheelchair for mobility and often requires support from a
caregiver. Over time, patients may also develop secondary complications such as
hypertension, osteoporosis, and bedsores. These comorbidities severely limit the
individuals ability to carry out activities of daily living, restrict social participation,
and affect the quality of life and mood (Suzuki et al. 2005).
A new neurorehabilitation therapy has been developed, different from the classi-
cal therapeutic techniques and based on robotic devices; it is referred to as
neurorobotic or neuroprosthetic training and includes devices such as the exoskel-
eton (Moreno et al. 2011). Spungen et al. (2013) maintain that robotics-assisted
powered exoskeletons represent a relatively new technology that has been shown to
be safe and effective in helping individuals with motor complete paraplegia to stand
and walk. An exoskeleton allows a paralyzed person to overcome environmental
barriers that preclude wheelchair use, such as stairs.
Initially, exoskeletons were used in gait disorder rehabilitation to assist with the
recovery of upper limb movement (Chaigneau et al. 2008). Researchers observed
that motor patterns of the hip, pelvis, and legs remained unchanged when users wore
a robotic gait-assisting exoskeleton (Kao et al. 2010; Lee et al. 2014) that reduced the
muscular effort required (Mooney et al. 2014). The exoskeletons implemented to
assist paraplegic patients with lower limb movements were passive ones (Rahman
et al. 2006); that is, the exoskeleton moves the patients body on a predened
trajectory, regardless of what the patient is doing (Nef and Riener 2012). Subse-
quently, the rst active exoskeletons were built (Quintero et al. 2012) that enabled
patients to move together with the robot in the desired direction (Nef and Riener
2012). These allowed patients with gait motor disorders not only to stand bolt
upright but also to move autonomously in their surroundings.
The exoskeleton has been used to assist patients with SCI by restoring their
functional abilities (Spungen et al. 2013) and to adapt physical activity in sport as
in the Rome marathon of March 22, 2015, when two paraplegic patients ran 1 km
2 S. Federici et al.
wearing an exoskeleton (Fondazione Santa Lucia 2015)as well as to enhance
strength and muscular endurance in military operations (Herr 2009). Unlike the
human skeleton, an exoskeleton supports the body weight externally, allowing the
user to follow through and to strengthen and improve the coordination of the
voluntary movements of the lower limbs. This technology has greater ecological
validity than other types of neurorobotic techniques for example, robotic-assisted
gait training as patients wearing an exoskeleton can walk and move autonomously
for a long period of time and on a wide range of walking surfaces. The range of
environments in which the exoskeleton can be used is also more extensive; it can be
used in the workplace or at home, as well as in a rehabilitation space, supporting
patients when performing functions critical to the activities of daily living.
ExoskeletonsDevelopment and Technical Data
Not all exoskeletons used to evaluate their effectiveness in gait rehabilitation are
currently commercialized. At present, only six main multinational companies pro-
duce and commercialize active lower limb exoskeleton suits; they are Ekso Bion-
ics, Cyberdyne, ReWalk Robotics, Parker Hannin Corporation, Rex
Bionics, and Honda.
Below, we rst present the development of the commercial exoskeletons and then
the main technical data of each of them.
Development
Ekso BionicsPioneering the world of exoskeletons, Berkeley ExoWorkswas
founded in 2005 when Kazerooni, Angold, and Harding partnered with members of
the Berkeley Robotics and Human Engineering Laboratory at the University of
California, Berkeley. The exoskeleton allows users to carry and even run with
weights of up to 200 lbs, over a variety of terrains. In addition, Berkeley Exo-
Worksintroduced the ExoClimber. It was designed to rapidly ascend stairs and
steep slopes. In 2007, Berkeley ExoWorksbecame Berkeley Bionics. In 2008,
Berkeley Bionicsunveiled their third-generation exoskeleton, the Human Univer-
sal Load Carrier (HULC). In 2010, Berkeley Bionicsdebuted what was then
called the Exoskeleton Lower Extremity Gait System(eLEGS), an intelligent,
bionic exoskeleton that actually allows wheelchair users to stand and walk over
ground; this was developed by Strausser. In 2011, Berkeley Bionicsbecame Ekso
Bionics, and, a year later, it produced Ekso,the rst commercialized robotic
exoskeleton for use in rehabilitative and medical facilities.
CyberdyneThe rst Cyberdyne exoskeleton prototype, named Hybrid Assistive
Limb (HAL) was proposed in 1989 by Sankai, a professor at Tsukuba University
Gait Rehabilitation with Exoskeletons 3
(Japan). The third HAL prototype, developed in the early 2000s, was attached to a
computer. Its battery alone weighed nearly 22 kilograms (49 lb) and required two
helpers to put on, making it very impractical. By contrast, a later HAL-5model
weighed only 10 kilograms (22 lb); its battery and control computer were strapped
around the waist of the wearer. Cyberdynebegan renting out the HAL suit for
medical purposes in 2008. In 2012, Cyberdynewas certied as ISO 13485 by
Underwriters Laboratories. In 2013, the HAL suit received a global safety certicate,
becoming the rst powered exoskeleton to do so, as well as the European Confor-
mity Certicate that permitted its use for medical purposes in Europe as the rst
medical treatment robot of its kind.
ReWalk RoboticsReWalk Robotics (originally Argo Medical Technologies)is
an Israeli medical device company that designs, develops, and commercializes
exoskeletons, allowing wheelchair-bound individuals to stand and walk again. In
2001, ReWalk Robotics created the ReWalk powered exoskeleton, approved by the
US Food and Drug Administration (FDA) in 2011. Currently, ReWalk designs are
intended for people with paraplegia. The system uses patented motion-sensing
technology, along with battery-powered motorized legs powering knee and hip
movements. The system is controlled by proprietary onboard computers and soft-
ware. The ReWalk system allows the user to sit, stand, walk, turn, and climb and
descend stairs. ReWalk provides two different operative systems: personal,
designed for everyday and all day use by individuals at home and in their commu-
nities, and rehabilitation,designed for training exercises and therapy in clinical
rehabilitation settings.
Parker Hannin CorporationVanderbilt University began testing its exoskele-
ton with paraplegics at a rehabilitation center in Atlanta, in 2010. In 2012, Hannin
signed an exclusive licensing agreement with Vanderbilt University for the right to
develop and manufacture a commercial version of the exoskeleton, which it plans to
release under the name Indego. In 2014, Parker Hannin entered into clinical trial
agreements for the exoskeleton with several major medical rehabilitation centers.
Rex BionicsThe British engineers Richard Little and Robert Irving set about
designing Robotic Exoskeleton (REX) when Robert was diagnosed with multiple
sclerosis in 2003. In 2007, Rex Bionics completed the rst prototype REX Personal.
The REX Rehab is designed for use in rehabilitation settings and can be adjusted to
t any user in few minutes. REX Rehab allows users to experience the psychological
and physiological benets of standing and walking again, as a part of a regular
rehabilitation program.
HondaIn 1999, in the area of humanoid robot research, Honda developed their
rst exoskeleton, the Walking Assist Devic e.In 2013, Honda began leasing the
Walking Assist Device to hospitals in Japan that provide rehabilitation training and
4 S. Federici et al.
physical therapy in the area of walking, to monitor its use and verify the practicality
of the device. Finally, in 2015, this exoskeleton was ofcially commercialized in
Japan.
Technical Data
Ekso BionicsEkso GT, the latest generation of Ekso Bionicsexoskeletons{ XE
exoskeleton}, is a wearable bionic suit that enables individuals with any amount
of lower extremity weakness to stand up and walk over ground with a natural, full
weight bearing, reciprocal gait. Walking is achieved by shifting the users weight to
activate sensors in the device which initiate steps. Battery-powered motors drive the
legs, replacing decient neuromuscular function. It provides a means for people with
even complete paralysis and minimal forearm strength to stand and walk. Moreover,
it helps patients to relearn proper step patterns and weight shifts using a functional
based platform and facilitates intensive step dosage over ground. Ekso can be used
by patients with various levels of paralysis or hemiparesis due to neurological
conditions such as CVA, SCI or disease, traumatic brain injury, or other illnesses.
Designed for utility and ease of use in a clinical setting, Ekso accommodates an
unprecedented spectrum of patients in motor ability.
The Ekso latest release has been designed for the needs of busy therapists treating
a wide range of patients in a single day. The suit is strapped over the users clothing
with easy adjustments, enabling transition between patients in as little as 5 min. Step
Generator software helps patients walk in their rst session to quickly achieve work
on gait patterning or step dosage. Progressive step modes help patients to develop
their skills. It represents a tool to enforce proper biomechanical alignments and
symmetrical gait patterns over ground.
Functioning: the Ekso exoskeleton adopts a humancomputer interface based on
gesture, which exploits sensors, observes actions made to determine intentions,
and acts accordingly.
Weight: 23 kg.
Maximum Speed: 1.6 km/h.
Battery Life: over 6 h.
Movements: walking in a straight line, standing up from a sitting position,
remaining raised for a long period of time, and sitting down from a stand up
position.
Crutches: necessary for this exoskeleton.
Who Can Use: people who can move independently from a wheelchair to a chair
(height: 1.50 m/1.90 m; weight: not exceeding 100 kg).
CyberdyneHAL is able to read bioelectric signals by only attaching the origi-
nally developed detectors on the surface of the wearers skin. By consolidating
Gait Rehabilitation with Exoskeletons 5
various information, HAL recognizes the types of motions the wearer intends. In
accordance with the recognized motions, HAL controls its power units. This func-
tion enables HAL to assist the wearers movements as he or she intends and exerts
more power than he or she ordinarily exerts. Moreover, when HAL has appropriately
assisted the motions of walking,the feeling I could walk!is fed back to the
brain. By this means, the brain gradually becomes able to learn the way to emit the
necessary signals for walking.This leads to the important rst step in walking by
the physically challenged person, without being assisted by HAL.
Functioning: HAL is characterized by two control systems. For instance, when a
person attempts to walk, the brain sends electrical impulses to muscles. When
they arrive at the muscles, faint bioelectrical signals appear on the skin surface.
With the rst of the two control systems, the Bio-Cybernetic Control System,
HAL assists the wearer with an intended movement. In the event that no good
bioelectrical signals are detectable due to some problems in the CNS or in the
muscles, HAL can be of use through the second of the two control systems, the
Robotic Autonomous Control System.
Weight: 23 kg (whole body type) 15 kg (legs-only type)
Maximum speed: 1.6 km/h
Battery life: 2 hours and 40 minutes
Movements: standing up from a chair, walking, and going up- and downstairs
Crutches: necessary for this exoskeleton
Who can use: people with weakened muscles or people with disabilities caused by
stroke and/or SCI
ReWalk RoboticsThe ReWalk Personal System can be used at home, work, or
other locations. It functions outdoors and on different surfaces or terrains. The
ReWalk can facilitate patients in sitting, standing, turning and climbing, and
descending stairs. The key prerequisites for use include the ability to use hands
and shoulders, a healthy cardiovascular system, and a minimal bone density.
Functioning: ReWalk control is based on motion sensors. Using sophisticated
algorithms, movements of the upper limbs are analyzed and used to trigger and
maintain the patterns of gait and other modes, such as going upstairs and moving
from a sitting to a standing position. In other words, ReWalk exoskeleton detects
movements of the upper limbs. The buttons on a remote control allows the user to
select various program settings and to choose the correct mode of movement:
walking, climbing stairs, sitting, getting up, etc.
Weight: 18 kg.
Maximum speed: 3 km/h.
Battery life: 8 hours. It can be recharged during the night.
Movements: standing, sitting, walking, going upstairs, and climbing and
descending slopes.
Crutches: necessary for this exoskeleton.
6 S. Federici et al.
Who can use: the system can accommodate a range of heights (160190 cm) or
weights (up to 100 kg). The key prerequisites for use include the ability to use
hands and shoulders, a healthy cardiovascular system, and a minimal bone density.
Parker Hannin CorporationIndego is a powered exoskeleton worn around the
waist and legs which allows individuals with SCI to stand and walk. At just 26 lbs,
Indegos design has no exposed cables or upper body apparatus and does not require
bulky backpack-mounted components. Indego mirrors natural human movement,
leans forward to initiate standing or walking, and leans backward to stop and sit.
Moreover, Indego has a slim prole that is compatible with standard mobility aids
and can be worn while seated in a wheelchair. Furthermore, a single-hand strapping
and retention system allows Indego to be put on, taken off, and adjusted to t without
assistance. Designed from the beginning for personal use, the features of Indego
make it well suited for use in the clinical setting and for an easy transition to use at
home.
Functioning: with the Indego, patients with SCI or other motor problems strap
their lower bodies into a piece of equipment similar in appearance to leg braces.
Gyroscopes and accelerators anticipate a patients steps by subtle upper body
motion, similarly to how a Segway works. Then, the Indego moves in concert
with the patients leg to take a step. The wearer uses his or her muscles to do the
work; the Indego provides a little extra help. Sensors determine how much power
is needed, eventually decreasing as the patient grows stronger.
Weight: 12.3 kg.
Maximum speed: 3 km/h.
Battery life:4h.
Movements: standing, walking, and walking on hard surfaces (including ramps
and slopes).
Crutches: necessary for this exoskeleton.
Who can use: Indego comes in interchangeable sizes and can accommodate
people from 155 cm to 193 cm in height and up to 113.5 kg in weight.
Rex BionicsDesigned for people with mobility impairments, REX is completely
self-supporting and rapidly adjustable for each user. Rex Bionics is working with
physiotherapists to develop the practice of robot-assisted physiotherapy. In a session
of robot-assisted physiotherapy, REX lifts patients from a sitting position into a
robot-supported standing position, allowing them to take part in a set of supported
walking and stretching exercises designed by specialist physiotherapists.
Functioning: REX is controlled by means of a joystick, not through sensors;
consequently no movement or function of nerves is needed to drive the
exoskeleton.
Weight: 38 kg.
Maximum speed: 1.8 km/h.
Battery life:2h.
Gait Rehabilitation with Exoskeletons 7
Movements: standing, walking, moving sideway, turning around, going up- and
downstairs, and walking on hard surfaces (including ramps and slopes).
Crutches: not necessary for this exoskeleton.
Who can use: the system can accommodate a range of heights (142195 cm),
weights (up to 100 kg), and hip width (up to 380 mm). The key prerequisites for
use include the ability to move autonomously and use a joystick.
HondaThe Walking Assist Device features a function to inuence the user to
achieve efcient walking based on the inverted pendulum model, which is a theory
of bipedal walking, and is designed as a device to be used in walking training. Three
training modes are available: (i) following, the exoskeleton inuences the users
walking motion based on the walking pattern of the user; (ii) symmetric, based on
the walking pattern of the user, the device inuences the user to achieve bilaterally
symmetric motions such as bending and extending both legs, and (iii) step, the
device inuences the users steps repeatedly to recover the rocker functions which
enable the smooth shifting of weight.
Functioning: the control computer activates motors based on data obtained from
hip angle sensors during walking, to improve the symmetry of the timing of each
leg lifting from the ground and extending forward and to promote a longer stride
for an easier walk.
Weight: 2.7 kg, approximately.
Maximum speed: n/a.
Battery life:1h.
Movements: indoor or outdoor (except when raining) on at oor/ground.
Crutches: not necessary for this exoskeleton.
Who can use: the system can accommodate a range of size-adjustable frames,
making it possible for more people with various body sizes/types to use the
Walking Assist Device.
The Effectiveness of Powered, Active Lower Limb Exoskeletons
in Gait Rehabilitation
We conducted a systematic review aimed at examining the rehabilitative capacity of
current models of active, powered lower limb exoskeletons when used in paraplegic
patients with gait disorders resulting from CNS lesions caused by, for example, SCIs
or CVAs. Relevant publications were retrieved from searches of PubMed, EBSCO,
Web of Science, Google Scholar, Scopus, and ProQuest electronic databases. Table 1
summarizes the results of the reviewed 33 studies, published between 2001 and
2016, according to the nine data items (country, study design, exoskeleton, sample
inclusion criteria, sample size, sample type, measures, strengths, and weaknesses)
extracted from each reviewed study.
These studies, mainly in the area of medical and engineering research, were
designed to test the safety or effectiveness of a particular device in an experimental
8 S. Federici et al.
Table 1 Summary of the 33 reviewed studies
Studies in
alphabetic
order Country Study design Exoskeleton
Sample inclusion
criteria
a
Sample
size
Sample
type Measures
b
Strengths Weaknesses
Aach et al.
(2013)
Germany Uncontrolled
clinical trial
HAL NA 4 SCI Observation
measures: walking
distance, walking
speed, and
walking time on
treadmill
Outcome
measures:
10 MWT, TUG,
and WISCI II
The exoskeleton
increases mobility
and functional
abilities and
decreases the risk
of secondary
injuries
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Aach et al.
(2014)
Germany Uncontrolled
clinical trial
HAL 1. Traumatic SCI
with chronic
incomplete (ASIA
B/C/D) or
complete paraplegia
(ASIA A) after
lesions of the conus
medullaris/cauda
equine with zones of
partial preservation
2. Motor
functions of hip and
knee extensor and
exor muscle groups
to be able to trigger
the exoskeleton
8 SCI Clinical measures:
Lower extremity
circumferences
Outcome
measures:
10 MWT, TUG,
6 MWT, WISCI II,
LEMS, and
Ashworth scale
The exoskeleton
increases mobility
and functional
abilities and
decreases the risk
of secondary
injuries
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
(continued)
Gait Rehabilitation with Exoskeletons 9
Table 1 (continued)
Studies in
alphabetic
order Country Study design Exoskeleton
Sample inclusion
criteria
a
Sample
size
Sample
type Measures
b
Strengths Weaknesses
Asselin et al.
(2015)
USA Uncontrolled
clinical trial
ReWalk 1. 1865 years of
age;
2. Height
152193 cm
3. Weight <
100 kg
4. At least
6 months after injury
5. Be
nonambulatory
8 SCI Observation
measures: oxygen
uptake (VO2) and
heart rate (HR)
1. The
exoskeleton
increases mobility
and functional
abilities and
decreases the risk
of secondary
injuries
2. The
exoskeleton use is
not physically
exhausting and
requires only a
little energetic
effort
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Belforte et al.
(2001)
Italy Experimental
trial
Advanced
reciprocating gait
orthosis (ARGO)
NA 1 SCI Observation
measures:
rotations and
applied torques for
each joint;
kinematic
magnitudes and
exchanged forces
The device is
ideal for the
rehabilitation
stage, given the
structures
modularity and
the extremely
exible means
used to regulate
gait
characteristics
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
10 S. Federici et al.
Benson et al.
(2016)
UK Uncontrolled
clinical trial
ReWalk 1. 1855 years of
age
2. Height
160190 cm
3. Weight <
100 kg
4. Male or
nonpregnant,
nonlactating female
5. AIS (ASIA
impairment scale)
grade A, B or & C,
according to the
ISNCSCI
(International
Standards for
Neurological
Classication of
SCI)
6. Motor level of
injury from C7 to
T12, according to
the ISNCSCI
7. Onset spinal
cord injury/
dysfunction at least
1 before screening
8. Able to stand or
maintain upright
position with or
without using a
standing device and
able to sit with hips
and knees 90
exion
5 SCI Outcome
measures: 6 MWT,
TUG, 10 MWT,
VAS, ISNCSCI,
SCI-specic
ADAPSS, and
ATD-PA
/ 1. Absence
of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
2. User
experience
with an
exoskeleton in
daily life
activities did
not meet
subjects
expectations
in terms of
perceived
benets and
impact on
quality of life
3. Presence
of skin
aberration
(continued)
Gait Rehabilitation with Exoskeletons 11
Table 1 (continued)
Studies in
alphabetic
order Country Study design Exoskeleton
Sample inclusion
criteria
a
Sample
size
Sample
type Measures
b
Strengths Weaknesses
Bishop et al.
(2012)
USA Uncontrolled
clinical trial
Tibion bionic
technologies
NA 1 SCI Outcome
measures: 6 MWT,
BBS, TUG, and
10 MWT
The rehabilitative
use of the
exoskeleton to
restore gait
disorders is safe
and practical
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Bortole et al.
(2015)
Spain Experimental
trial
H2 NA 3 Stroke Outcome
measures: 6 MWT,
BBS, TUG,
Barthel index, and
FM-LE
Observation
measures: walking
angular
kinematics,
interaction torques
and motor torques
for left and right
hip, and knee and
ankle joints
The rehabilitative
use of the
exoskeleton to
restore gait
disorders is safe
and practical
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Esquenazi
et al. (2012)
USA Experimental
trial
ReWalk 1. 1855 years of
age
Motor-complete
cervical (C7-8) and
thoracic (T1-T12)
12 SCI Observation
measures: distance
walked in 6 min,
time spent to cover
10 m
The exoskeleton
allows restoration
of a gait pattern
comparable to
1. Absence
of a
randomized
clinical trial
design
12 S. Federici et al.
SCI
2. Male and
nonpregnant,
nonlactating woman
3. At least
6 months after injury
4. Regular use of a
Reciprocating Gait
Orthosis (RGO) or
KAFOs or able to
stand using a
standing device
Height 160190 cm
5. Weight <
100 kg
Outcome
measures: 6 MWT
and 10 MWT
normal over
ground walking
comparing
exoskeleton
use to
conventional
gait training
2. Wearability
criteria are too
restrictive
Farris et al.
(2014)
USA Experimental
trial
Vanderbilt lower
limb
exoskeleton,
kneeanklefoot
orthoses
(KAFOs)
NA 1 SCI Outcome
measures:
10 MWT, TUG,
and 6 MWT
The exoskeleton
assists paraplegic
patients to
perform gait
activities faster
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Farris et al.
(2011)
USA Experimental
trial
Vanderbilt lower
limb exoskeleton
NA 1 SCI Observation
measures: Hip and
knee joint angle
trajectories during
walking and
average walking
speed
The exoskeleton
allows restoration
of a gait pattern
comparable to
normal over
ground walking
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
(continued)
Gait Rehabilitation with Exoskeletons 13
Table 1 (continued)
Studies in
alphabetic
order Country Study design Exoskeleton
Sample inclusion
criteria
a
Sample
size
Sample
type Measures
b
Strengths Weaknesses
Farris et al.
(2012)
USA Experimental
trial
Vanderbilt lower
limb exoskeleton
NA 1 SCI Observation
measures: knee
joint torque
The exoskeleton
assists paraplegic
patients to
perform gait
activities faster
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Hartigan
et al. (2015)
USA Uncontrolled
clinical trial
Indego 1. 1855 years of
age;
2. Complete or
incomplete SCI,
with injury levels
ranging from L1 to
C5;
3. Height
155191 cm;
4. Weight <
113 kg;
5. AIS A, B, C, or
D
16 SCI Outcome
measures:
10 MWT and
6 MWT
The exoskeleton
increases mobility
and functional
abilities and
decreases the risk
of secondary
injuries
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Ikehara et al.
(2011)
Japan Experimental
trial
Walking assist
device
NA 2 NA Observation
measures: video
recording of
subjectswalking
The device
reproduces the
power of kicking
motions at the
ankle joints when
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
14 S. Federici et al.
controlled by the
hybrid system
use to
conventional
gait training
Kawamoto
et al. (2010)
Japan Experimental
trial
HAL NA 1 Stroke Observation
measures: knee
joint angle
A larger knee
angle is measured
during leg exion
while participants
wear the
exoskeleton
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Kolakowsky-
Hayner et al.
(2013)
USA Uncontrolled
clinical trial
Ekso NA 8 SCI Observation
measures: Skin
evaluation; blood
pressure; pain
level; spasticity,
time, and level of
assistance needed
to transfer into and
on device; time
ambulating;
assistive devices
used during
ambulation; step
length; and
distance walked
1. The
rehabilitative use
of the exoskeleton
to restore gait
disorders is safe
and practical
2. The
exoskeleton
increases mobility
and functional
abilities and
decreases the risk
of secondary
injuries
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
(continued)
Gait Rehabilitation with Exoskeletons 15
Table 1 (continued)
Studies in
alphabetic
order Country Study design Exoskeleton
Sample inclusion
criteria
a
Sample
size
Sample
type Measures
b
Strengths Weaknesses
Li et al.
(2015)
China Uncontrolled
clinical trial
Bionic leg 1. Patients could
actively move their
legs and walk more
than 10 m without a
walking aid
2. No neurologic
disorders,
uncontrolled
hypertension,
cognitive decits
(MMSE<23)
3 Stroke Outcome
measures: BBS,
FM-LE, and
electromyography
(EMG)
Observation
measures: video
recording of
subjectswalking
The use of the
exoskeleton
improves the
participantsgait
performance,
muscle activation,
and walking
speed
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Mori et al.
(2006)
Japan Experimental
trial
ABLE system NA 1 NA Observation
measures: time
response of the
angles and electric
currents of each
joint
The subject
succeeded in
standing up
wearing the
exoskeleton
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Neuhaus
et al. (2011)
USA Experimental
trial
MINA 1. Traumatic SCI
with chronic
incomplete (ASIA
B/C/D) or complete
paraplegia (ASIA A)
2. WISCI level
9 or higher
2 SCI Observation
measures:
conversation with
the user during
walking
The exoskeleton
use is not
physically
exhausting and
requires only a
little cognitive
effort
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
16 S. Federici et al.
Nilsson et al.
(2014)
Sweden Uncontrolled
clinical trial
HAL 1. Time since
stroke onset of <
7 weeks
2. Able to sit on a
bench with/without
supervision at least
ve minutes
3. Unable to walk
independently
4. Sufcient
postural control
5. Ability to
understanding
instruction
6. Body size
compatible with the
HAL suit
8 Stroke Observation
measures: walking
speed
Outcome
measures: NIHSS,
FM-LE, BBS,
TUG, 10 MWT,
S-COVS, FAC,
FES(S), I, FIM,
and VAS
The rehabilitative
use of the
exoskeleton
restoring gait
disorders is safe
and practical
1. Absence
of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
2. Wearability
criteria are too
restrictive
Quintero
et al. (2012)
USA Experimental
trial
Vanderbilt lower
limb exoskeleton
NA 1 SCI Outcome
measures: TUG
The exoskeleton
provides
appropriate user-
initiated control
of sitting,
standing, and
walking
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Raab et al.
(2016)
Germany Uncontrolled
clinical trial
ReWalk NA 1 SCI Outcome
measures: SF-36,
BBS, DGI
The exoskeleton
increases mobility
and functional
abilities and
decreases the risk
of secondary
injuries
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
(continued)
Gait Rehabilitation with Exoskeletons 17
Table 1 (continued)
Studies in
alphabetic
order Country Study design Exoskeleton
Sample inclusion
criteria
a
Sample
size
Sample
type Measures
b
Strengths Weaknesses
Sanz-
Merodio
et al. (2012)
Spain Experimental
trial
ATLAS NA 1 NA Observation
measures: joint
angles
Experiments
validated a good
controlled
performance in
following the gait
pattern given by
the parameterized
trajectory
generator
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Sczesny-
Kaiser et al.
(2013)
German Uncontrolled
clinical trial
HAL NA 4 SCI Outcome
measures: fMRI
and EMG
Reduced
somatosensory
rst area
(S1) activation of
the activated area
in both
hemispheres after
tactile stimulation
of the index nger
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Spungen
et al. (2013)
USA Uncontrolled
clinical trial
ReWalk 1. 1865 years of
age
2. Motor-
complete paraplegia
(T1T12)
3. Greater than
6 months elapsed
since the SCI
4. Height
160190 cm
5. Weigh <
100 kg
7 SCI Observation
measures: walking
speed
The exoskeleton
allows restoration
of gait pattern
comparable to
normal over
ground walking
1. Absence
of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
2. Wearability
criteria are too
restrictive
18 S. Federici et al.
Stein et al.
(2014)
USA Controlled
clinical trial
Bionic leg 1. Single stroke
(ischemic or
hemorrhagic)
causing signicant
leg weakness and
gait alterations at
least 6 months
before study entry
2. Stroke
conrmation
through CT or MRI
3. Independence
in household
ambulation with or
without facilitator
20 Stroke Outcome
measures:
10 MWT, TUG,
6 MWT, 5XSST,
Rombergs test,
EFAP, BBS, and
CAFE 40
/ Robotic
therapy for
ambulatory
stroke patients
with chronic
hemiparesis
and using a
robotic knee
brace resulted
in only modest
functional
benets, in
comparison
with a group
receiving only
exercise
intervention
Strausser and
Kazerooni
(2011)
USA Experimental
trial
eLEGS NA 5 SCI Observation
measures: knee
angle and time
practicing
The exoskeleton
is easy to learn
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Strausser
et al. (2010)
USA Experimental
trial
Human
Universal Load
Carrier (HULC)
NA 4 SCI Observation
measures: video
recording of
subjectswalking
The exoskeleton
increases mobility
and functional
abilities and
decreases the risk
of secondary
injuries
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
(continued)
Gait Rehabilitation with Exoskeletons 19
Table 1 (continued)
Studies in
alphabetic
order Country Study design Exoskeleton
Sample inclusion
criteria
a
Sample
size
Sample
type Measures
b
Strengths Weaknesses
Sylos-Labini
et al. (2014)
Italy Experimental
trial
MindWalker
exoskeleton
1. 1845 years of
age
2. Traumatic/non-
traumatic SCI
3. At least
5 months after injury
4. Complete
lesion below T7
5. Inability to
ambulate
26
10 SCI Observation
measures: joint
angles and torques
Outcome
measures: EMG
The exoskeleton
allows restoration
of gait pattern
comparable to
normal over
ground walking
1. Absence
of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
2. Wearability
criteria are too
restrictive
Talaty et al.
(2013)
USA Experimental
trial
ReWalk 1. Joint integrity/
absence of fractures
that prevent walking
2. Standing alone
also with facilitator
3. A complete
neurological
evaluation to assess
motor and
physiological
functioning
4. Absence of
osteoporosis (BMD
>2.5) at the right
limb femoral neck
and the L2 to L4
spine
12 SCI Clinical measures:
isometric muscle
strength
Observation
measures: video
recording of
subjectswalking
and walking speed
Outcome
measures:
EMG
The exoskeleton
provides
fundamentally
symmetric gait
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
20 S. Federici et al.
Tsukahara
et al. (2009)
Japan Experimental
trial
HAL NA 1 SCI Observation
measures: knee
joint angle
The exoskeleton
products a
standing-up and a
sitting motion
support systems
for completely
paraplegic
patients
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Tsukahara
et al. (2010)
Japan Experimental
Trial
HAL NA 1 SCI Observation
measures:
knee joint angle
The exoskeleton
products a
standing-up and a
sitting motion
support systems
for completely
paraplegic
patients
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
Watanabe
et al. (2014)
Japan Controlled
clinical trial
HAL 1. Hemiparesis
resulting from
unilateral ischemic
or hemorrhagic
stroke
2. Time since
stroke onset of <
6 months
22 Stroke Clinical measures:
isometric muscle
strength
Observation
measures:
maximum walking
speed
Outcome
measures: FAC,
TUG, 6 MWT,
SPPB, and FM-LE
Israel ReWalk 6 SCI
(continued)
Gait Rehabilitation with Exoskeletons 21
Table 1 (continued)
Studies in
alphabetic
order Country Study design Exoskeleton
Sample inclusion
criteria
a
Sample
size
Sample
type Measures
b
Strengths Weaknesses
Zeilig et al.
(2012))
Experimental
trial
1. 1670 years of
age
2. Weight <
100 kg
3. Height from
155200 cm
4. Complete
motor impairment
C7C8 or T1T12
5. At least
6 months since
injury
6. Regular user of
a RGO or
therapeutic standing
frame
Observation
measure: distance
walked in
6 minutes
Outcome
measures:
10 MWT and
TUG
The exoskeleton
increases
mobility and
functional
abilities and
decreases the risk
of secondary
injuries
Absence of a
randomized
clinical trial
design
comparing
exoskeleton
use to
conventional
gait training
NA not available: in the study inclusion criteria were not reported
a
All the measuresabbreviations are explained in the Table 2
b
See Table 2for the measure reference details
22 S. Federici et al.
trial or to evaluate its rehabilitative effectiveness in an uncontrolled or controlled
clinical trial.Participants enrolled in experimental groups comprised patients with
CVA, SCI, and gait disorders without etiological data. They were recruited in a wide
range of countries, such as the USA, Japan, Germany, Sweden, Israel, Italy, and
Spain.
In the 33 studies included, three types of measures were used:
Clinical measures,todene the subjects functional prole before treatment
such as isometric muscle strength (hip exion and extension, knee exion and
extension, trunk exion and extension, ankle dorsi-/plantar exion) and lower
extremity circumferences
Outcome measures (standardized tests, neurophysiological, or neuroimaging
techniques), to evaluate the effectiveness of a treatment
Observation measures, to observe the subjects functional performance while
wearing the exoskeleton such as knee joint angle or torque, a video recording
of a subject walking, hip and knee joint angle trajectories during walking, the time
practicing, and distance walked in a certain time period.
Table 2provides details of the indicators and the studies in which they were used.
In the following subsections, we discuss 16 brands of exoskeletons experimen-
tally tested in the scientic literature, of which ve have already been commercial-
ized (HAL, Ekso, ReWalk, Indego, and Walking Assist Device) and 11 are not yet
commercialized (Vanderbilt lower limb exoskeleton, Human Universal Load Carrier
(HULC), MindWalker exoskeleton, advanced reciprocating gait orthosis (ARGO),
eLEGS, X1 robotic exoskeleton (MINA), ATLAS, ABLE system, Tibion Bionic
Technologies, Bionic Leg, and H2 robotic exoskeleton).
Hybrid Assistive Limb (HAL)The HAL exoskeleton was tested with paraplegic
subjects with a SCI at the T10 level, complete or incomplete, or having hemiparesis
after a stroke (Aach et al. 2013,2014; Kawamoto et al. 2010; Nilsson et al. 2014;
Sczesny-Kaiser et al. 2013; Tsukahara et al. 2009,2010; Watanabe et al. 2014).
Clinical, observational, and outcome measures administered to investigate the
effectiveness of HAL varied. For example, Sczesny-Kaiser et al. (2013) used
functional magnetic resonance imaging and electromyography (EMG) to evaluate
cortical excitability and plastic changes after a three-month period of treadmill
training supported by HAL.
Taken together, the results of these studies guaranteed the systems safety (Nils-
son et al. 2014) and its effectiveness. Paraplegic patients gained signicant increases
in over ground walking functional abilities (Aach et al. 2013,2014), and a larger
knee angle was measured during leg exion (Kawamoto et al. 2010). In addition,
diagnostic imaging displayed an augmented paired pulse inhibition of somatosen-
sory evoked potentials in both hemispheres following median nerve stimulation at
the wrist. There was also a reduced somatosensory cortex activation of the activated
area in both hemispheres after tactile stimulation of the index nger (Sczesny-Kaiser
Gait Rehabilitation with Exoskeletons 23
et al. 2013). Finally, even a gait training program with the single-leg version of HAL
could facilitate independent walking more efciently than conventional gait training
(Watanabe et al. 2014).
ReWalk The ReWalk exoskeleton was tested with paraplegic patients with complete
SCIs, at the C7-T12 and the T1-T12 level.
By using the ReWalk, paraplegic patients were able to walk independently,
supervised by one person (Raab et al. 2016), and to achieve a level of walking
prociency that was close to that needed for limited community ambulation in an
urban setting (Asselin et al. 2015; Benson et al. 2016; Esquenazi et al. 2012;
Spungen et al. 2013), for example, for a distance of 100 m (Zeilig et al. 2012),
with a fundamentally symmetrical gait (Talaty et al. 2013). Daily use of the exo-
skeleton seemed to increase activity energy expenditure, but this would be expected
to have positive cardiopulmonary and metabolic benets. The level of effort required
to use the ReWalk exoskeleton system to ambulate appears to be acceptable and, as
such, could be envisioned as a device that people with SCI would use in their daily
lives (Asselin et al. 2015).
Moreover, quality of life, mobility, risk of falling, motor skills, and control
of bladder and bowel functions were improved after robot-assisted gait
training (Raab et al. 2016). Nonetheless, the presence of skin aberrations was
unexpectedly high, and the use of the exoskeleton generally did not meet subjects
expectations in terms of perceived benets and impact on quality of life (Benson
et al. 2016).
Vanderbilt Lower Limb Exoskeleton The Vanderbilt lower limb exoskeleton was
developed by a team of engineers of the Vanderbilt University, at Nashville in
Tennessee, chaired by H. A. Quintero (Farris et al. 2011,2012,2014; Quintero
et al. 2012). Their clinical trials involved paraplegic patients with motor and sensory
complete SCIs at the T10 level.
Findings showed the Vanderbilt lower limb exoskeleton system assisted paraple-
gic patients to perform gait activities faster (Farris et al. 2012,2014), with knee and
hip joint amplitudes similar to those observed in non-SCI walking (Farris et al.
2011).
Human Universal Load Carrier (HULC)The HULC was developed by
H. Kazerooni and his team at Ekso Bionics in the USA. Given that the HULC is
designed to assist able-bodied individuals by powering knee movements only in
extension, just one study on its effectiveness met our inclusion criteria (Strausser
et al. 2010). In this study, double-acting hydraulic cylinders replaced the single
acting ones of the HULC, providing powered exion and extension at the knee.
Likewise, bracing used in the exoskeleton was augmented to support a patient with
limited leg and torso muscle control. This clinical trial involved paraplegic patients
with a motor complete SCI at the T5-T10 level.
24 S. Federici et al.
The studys purpose was to discover whether the development of an exoskeleton
for medical use would facilitate an active life in paraplegic people, so reducing the
occurrence of secondary complications. The results conrmed that the HULC
exoskeleton, when readapted for medical use, is able to safely increase mobility
for those who are unable to walk unaided.
MindWalker Exoskeleton The MindWalker was developed by a European consor-
tium coordinated by M. Ilzkovitz and funded by the European Commission in 2009.
Only one study (Sylos-Labini et al. 2014) involved participants with an SCI at the
T7-L1 level.
The aim of this study was to quantify the level of muscle activity in a sample of
intact and injured patients while they walked with MindWalker. The measures used
were EMG activity, joint angles, and torques. The results showed that, in SCI
patients, EMG activity of the upper limb muscles was augmented, while activation
of the leg muscles was minimal. Contrary to expectations, however, in the neuro-
logically intact subjects, EMG activity of the leg muscles was similar, or even
greater, during exoskeleton-assisted walking compared to normal over ground
walking. In addition, signicant variations in the EMG waveforms were found in
different walking conditions; the most variable pattern was observed in the ham-
string muscles. Overall, the results are consistent with a nonlinear reorganization of
the locomotor output when using the robotic stepping devices.
Advanced Reciprocating Gait Orthosis (ARGO)Only one study tested the ARGO,
produced by RSLSteeper, with paraplegic patients (Belforte et al. 2001). This
clinical trial involved one participant with a motor complete SCI at the T3 level,
enrolled in Italy. The design and construction of the ARGO, and experimental testing
to assist locomotion in paraplegic subjects when using the ARGO, were described.
Findings showed the device is ideal for the rehabilitation stage, given the structures
modularity and the extremely exible means used to regulate gait characteristics.
Walking Assist Device The Walking Assist Device was tested by a team of engi-
neers led by T. Ikehara.
One of their studies (Ikehara et al. 2011) involved two participants with motor
paralysis, enrolled in Japan. The results of the experimental study showed that the
device could reproduce the power of kicking motions at the ankle joints when
controlled by the hybrid system.
Exoskeleton Lower Extremity Gait System (eLEGS)Only one clinical trial
(Strausser and Kazerooni 2011) was carried out on this system.
This study involved ve participants with no leg motion due to SCI or ataxia,
recruited in the USA. The authors tested whether the eLEGS was intuitive and easy
to learn and use. The measures used were knee angle and time practicing. The results
Gait Rehabilitation with Exoskeletons 25
Table 2 Summary of the measures adopted in the studies reviewed ordered by largest to smallest frequency in use
Measure Abbreviation Frequency
Measure
type
Study where the measure was
administered
Measures
references
Timed up and go test TUG 10 Outcome
measures
Aach et al. (2013,2014), Bishop et al.
(2012), Bortole et al. (2015), Farris et al.
(2014), Nilsson et al. (2014), Quintero
et al. (2012), Stein et al. (2014), Watanabe
et al. (2014), Zeilig et al. (2012)
Podsiadlo and
Richardson (1991)
10-meter walk test 10 MWT 9 Outcome
measures
Aach et al. (2013,2014), Bishop et al.
(2012), Esquenazi et al. (2012), Farris
et al. (2014), Hartigan et al. (2015),
Nilsson et al. (2014), Stein et al. (2014),
Zeilig et al. (2012)
Peters et al. (2014)
6-minute walking test 6 MWT 8 Outcome
measures
Aach et al. (2014), Bishop et al. (2012),
Bortole et al. (2015), Esquenazi et al.
(2012), Farris et al. (2014), Hartigan et al.
(2015), Stein et al. (2014), Watanabe et al.
(2014)
Reybrouck (2003)
Knee joint angle or torque / 7 Observation
measures
Bortole et al. (2015), Farris et al. (2011,
2012), Kawamoto et al. (2010), Strausser
and Kazerooni (2011), Tsukahara et al.
(2009,2010)
/
Berg balance scale BBS 6 Outcome
measures
Bishop et al. (2012), Bortole et al. (2015),
Nilsson et al. (2014), Stein et al. (2014)
Li et al. (2015), Raab et al. (2016)
Downs et al.
(2013)
Walking speed / 6 Observation
measures
Aach et al. (2013), Farris et al. (2011),
Nilsson et al. (2014), Spungen et al.
/
26 S. Federici et al.
(2013), Talaty et al. (2013), Watanabe
et al. (2014)
Distance walked in a certain time period / 4 Observation
measures
Aach et al. (2013), Esquenazi et al.
(2012), Kolakowsky-Hayner et al. (2013),
Zeilig et al. (2012)
/
Electromyography EMG 4 Outcome
measures
Li et al. (2015), Sczesny-Kaiser et al.
(2013), Sylos-Labini et al. (2014), Talaty
et al. (2013)
Mohseni Bandpei
et al. (2014)
Fugl-Meyer assessment for lower
extremity
FM-LE 4 Outcome
measures
Bortole et al. (2015), Li et al. (2015),
Nilsson et al. (2014), Watanabe et al.
(2014)
Park and Choi
(2014)
Video recording of subjects walking / 4 Observation
measures
Ikehara et al. (2011), Li et al. (2015),
Strausser et al. (2010), Talaty et al. (2013)
/
Barthel index BI 2 Outcome
measures
Bortole et al. (2015), Nilsson et al. (2014) Cuesta-Vargas and
Perez-Cruzado
(2014)
Functional ambulation category FAC 2 Outcome
measures
Nilsson et al. (2014), Watanabe et al.
(2014)
Mehrholz et al.
(2007)
Isometric muscle strength (hip/knee/
trunk exion and extension, ankle
dorsi/plantar exion)
/2 Clinical
measures
Talaty et al. (2013), Watanabe et al. (2014)/
Time practicing / 2 Observation
measures
Kolakowsky-Hayner et al. (2013),
Strausser and Kazerooni (2011)
/
Walking index for SCI II WISCI II 2 Outcome
measures
Aach et al. (2013,2014) Ditunno et al.
(2013)
Ashworth scale / 1 Outcome
measures
Aach et al. (2014) Pandyan et al.
(1999)
Assistive devices used during
ambulation
/ 1 Observation
measures
Kolakowsky-Hayner et al. (2013) /
Blood pressure / 1 Kolakowsky-Hayner et al. (2013) /
(continued)
Gait Rehabilitation with Exoskeletons 27
Table 2 (continued)
Measure Abbreviation Frequency
Measure
type
Study where the measure was
administered
Measures
references
Observation
measures
California functional evaluation 40 CAFE 40 1 Outcome
measures
Stein et al. (2014) Fung et al. (1997)
Clinical outcome variable scale, Swedish
version
S-COVS 1 Outcome
measures
Nilsson et al. (2014) Andersson and
Franzen (2015)
Conversation with the user during
walking
/ 1 Observation
measures
Neuhaus et al. (2011)/
Dynamic gait index DGI 1 Outcome
measures
Raab et al. (2016) Tinetti (1986)
Emory functional ambulation prole EFAP 1 Outcome
measures
Stein et al. (2014) Wolf et al. (1999)
Falls efcacy scale, Swedish version FES(S) 1 Outcome
measures
Nilsson et al. (2014) Hellstrom et al.
(2002)
Five times sit-to-stand test 5XSST 1 Outcome
measures
Stein et al. (2014) Whitney et al.
(2005)
Functional independence measure FIM 1 Outcome
measures
Nilsson et al. (2014) Saji et al. (2015)
Functional magnetic resonance imaging fMRI 1 Outcome
measures
Sczesny-Kaiser et al. (2013) Buxton (2013)
Heart rate HR 1 Observation
measures
Asselin et al. (2015)/
Kinematic magnitudes and exchanged
forces
/ 1 Observation
measures
Belforte et al. (2001)/
Lower extremity circumference / 1 Clinical
measures
Aach et al. (2014)/
28 S. Federici et al.
Lower extremity motor score LEMS 1 Outcome
measures
Aach et al. (2014) Shin et al. (2011)
National Institutes of Health Stroke scale NIHSS 1 Outcome
measures
Nilsson et al. (2014) Yang et al. (2014)
Oxygen uptake VO2 1 Observation
measures
Asselin et al. (2015)/
Pain level / 1 Observation
measures
Kolakowsky-Hayner et al. (2013) /
Rombergs test / 1 Outcome
measures
Stein et al. (2014) Agrawal et al.
(2011)
Rotations and applied torques for each
joint
/ 1 Observation
measures
Belforte et al. (2001)/
Short form health survey SF-36 1 Outcome
measures
Raab et al. (2016) McHorney et al.
(1993)
Short physical performance battery SPPB 1 Outcome
measures
Watanabe et al. (2014) Stookey et al.
(2014)
Skin evaluation / 1 Observation
measures
Kolakowsky-Hayner et al. (2013) /
Spasticity / 1 Observation
measures
Kolakowsky-Hayner et al. (2013) /
Step length / 1 Observation
measures
Kolakowsky-Hayner et al. (2013) /
Time and level of assistance needed to
transfer into and on device
/ 1 Observation
measures
Kolakowsky-Hayner et al. (2013) /
Time response of the angles and electric
currents of each joint
/ 1 Observation
measures
Mori et al. (2006)/
Visual analogue scale VAS 1 Outcome
measures
Nilsson et al. (2014) Reed and Van
Nostran (2014)
Gait Rehabilitation with Exoskeletons 29
showed that the eLEGShuman machine interface was easy to learn; all ve subjects
were able to quickly learn how to use it. Indeed, the walking performance of the ve
participants displayed an increased time between the heel off and the step, as
compared to the able-bodied user. However, this time was decreased in the experi-
enced user, while the user with no experience with the device had an average time of
0.859 sec, the experienced user was able to reduce the lag time to 0.590 s.
X1 Robotic Exoskeleton (MINA)The team of the Institute for Human and Machine
Cognition led by P. Neuhaus and the NASA Johnson Space Center jointly developed
MINA (Neuhaus et al. 2011).
The team carried out a clinical trial involving two participants with motor
complete SCIs at the T10 level, recruited in the USA. The recruitment inclusion
criteria stipulated an American Spinal Injury Association Impairment Scale of either
an A (complete) or B (incomplete) and a Walking Index for Spinal Cord Injury
(WISCI) of level 9 (ambulates with a walker, with braces, and no physical
assistance, 10 m). The paper presents a clinical and rehabilitative evaluation of the
MINA exoskeleton. The measures used qualitatively evaluated the cognitive effort
required to use MINA: researchers could talk with the subjects while they walked
with MINA. In addition, static standing balance stability was tested by having the
subjects catch and throw a ball while standing on both legs and using one crutch for
balance. Findings provided evidence that MINA currently facilitates paraplegics
walking mobility at speeds of up to 0.20 m/sec. In addition, MINA is not physically
taxing and requires little cognitive effort, allowing the user to converse and maintain
eye contact while walking.
ATLAS The Center for Automation and Robotics in Spain developed the prototype
of the ATLAS exoskeleton to help a quadriplegic child to walk. Its development and
main features were tested by D. Sanz-Merodio and colleagues (Sanz-Merodio et al.
2012).
This clinical trial involved one participant, a Spanish girl aged 8 years, affected by
quadriplegia. Experiments validated a good controlled performance in following the
gait pattern given by the parameterized trajectory generator.
ABLE The ABLE system was designed and tested in Japan by Y. Mori and
collaborators at Ibaraki University, in the Department of Intelligent Systems Engi-
neering (Mori et al. 2006).
This clinical trial involved one participant with motor paralysis, recruited in
Japan. Mori and his team developed a standing style transfer system for a person
with disabled legs. They proposed a new motion technique and compared it to their
previous system (Mori et al. 2004). The measures used were the time response of the
angles of the joints and electric currents, corresponding with the torque of each joint.
30 S. Federici et al.
The subject succeeded in standing up; a large arm force was needed in the beginning,
but was not needed afterward.
Tibion Bionic Technologies In 2013, Tibion Bionic Technologies was acquired by
AlterG that now produces the exoskeleton tested by L. Bishop of Columbia Univer-
sity in 2012 (Bishop et al. 2012). This clinical trial involved one participant with a
motor incomplete SCI at the C5-C6 level, enrolled in USA. Study outcomes
suggested that the use of this device, during a physical therapy program for an
individual with incomplete SCI, is practical and useful when used in addition to the
standard training.
Bionic Leg The Bionic Leg, produced by the Californian AlterG, is a powered knee
orthosis for patients with unilateral neurologic or orthopedic conditions, tested by
the team of the Department of Rehabilitation and Regenerative Medicine, Columbia
University College of Physicians and Surgeons, led by J. Stein (Li et al. 2015; Stein
et al. 2014).
These clinical trials involved hemiparesis patients after a CVA. Subjects were
required to be independent in household ambulation (with or without the use of
unilateral assistive devices and with or without the use of anklefoot orthoses). The
study of Stein et al. (Li et al. 2015, Stein et al. 2014) was designed to test how the
Bionic leg restores mobility in stroke survivors in their living environments, while Li
et al. (2015) aimed to demonstrate the training effects of a 3-week robotic leg
orthosis and to investigate possible mechanisms of the sensorimotor alterations
and improvements by using gait analysis and EMG.
Outcomes suggested that robotic therapy for ambulatory stroke patients with
chronic hemiparesis and using a robotic knee brace resulted in only modest func-
tional benets, in comparison with a group receiving only exercise intervention, for
example, without using the Bionic Leg (Stein et al. 2014). The 3-week training
period, using the wearable orthoses, improved the participantsgait performance and
improved muscle activation and walking speed (Li et al. 2015).
Ekso One study tested the Ekso exoskeleton (Kolakowsky-Hayner et al. 2013). The
study involved participants with a motor complete SCI. The main inclusion criteria
for participants stipulated a body size compatible with the Ekso suit.
The main goal of the study was to evaluate the feasibility and safety of using Ekso
to aid ambulation in a group of individuals with SCI who had completed their initial
SCI rehabilitation. Secondarily, training effects with the progressive use of Ekso
were evaluated in terms of time tolerated, distance traveled, and assistance needed.
Outcomes suggest that Ekso is safe for those with a complete thoracic SCI in a
controlled environment, in the presence of experts. Ekso may eventually enhance
mobility in those without volitional lower extremity function. There appears to be a
training effect in the device.
Gait Rehabilitation with Exoskeletons 31
Indego The Indego exoskeleton was tested by the team of Virginia C. Crawford
Research Institute, Shepherd Center, Atlanta, Georgia (Hartigan et al. 2015).
This study was conducted to evaluate mobility outcomes for 16 SCI subjects with
injury levels (ranging from C5 complete to L1 incomplete) after ve gait training
sessions with a powered exoskeleton. The primary goal was to characterize the ease
of learning and usability of the system. Outcome measures of the study included the
10-meter walk test (10 MWT) and the 6-minute walk test (6 MWT). Results
highlighted that the average walking speed was 0.22 m/sec for persons with C56
motor complete tetraplegia, 0.26 m/sec for T1T8 motor complete paraplegia, and
0.45 m/sec for T9L1 paraplegia. Distances covered in 6 min averaged 64 m for
those with C5C6, 74 m for T1T8, and 121 m for T9L1. Tetraplegic and
paraplegic patients learned to use the Indego exoskeleton quickly and could manage
a variety of surfaces. The walking speeds and distances achieved also indicated that
some individuals with paraplegia could quickly become limited community
ambulators using this system.
H2 Robotic Exoskeleton The Exo-H2 has been the result of many years of research
in the Grupo de Bioingeniería of the Spanish National Research Council (CSIC),
who has conceded an exclusive license to Technaid S.L. for the design, manufactur-
ing, and commercial exploitation of the system.
Bortole et al. (2015) evaluated the safety and usability of the H2 robotic exoskel-
eton for gait rehabilitation in three hemiparetic stroke patients across 4 weeks of
training per individual (approximately 12 sessions). Results showed that the training
was well tolerated and that H2 appears to be safe and easy to use. The system is
robust and safe when applied to assist a stroke patient performing an over ground
walking task.
Conclusions
In this chapter, we have reviewed the clinical effectiveness in rehabilitation of
various types of active, powered, and wearable lower limb exoskeletons used to
facilitate and rehabilitate paraplegic patientsgait disorders resulting from serious
CNS lesions due to, for example, SCIs or CVAs.
The literature review revealed that the exoskeletons subjected to the highest
number of studies were the HAL (Aach et al. 2013,2014; Kawamoto et al. 2010;
Nilsson et al. 2014; Sczesny-Kaiser et al. 2013; Tsukahara et al. 2009,2010;
Watanabe et al. 2014), the ReWalk (Asselin et al. 2015; Benson et al. 2016;
Esquenazi et al. 2012; Raab et al. 2016; Spungen et al. 2013; Talaty et al. 2013;
Zeilig et al. 2012), and the Vanderbilt lower limb exoskeleton (Farris et al. 2011,
2012,2014; Quintero et al. 2012).
By qualitatively analyzing the results for each type of exoskeleton, it was found
that the rehabilitative use of an exoskeleton to restore gait disorders is safe and
32 S. Federici et al.
practical (Bishop et al. 2012; Bortole et al. 2015; Kolakowsky-Hayner et al. 2013;
Nilsson et al. 2014), is not physically exhausting, and requires only a little cognitive
(Neuhaus et al. 2011) or energetic (Asselin et al. 2015) effort. In addition, it is easy to
learn (Strausser and Kazerooni 2011), can increase mobility and functional abilities,
and decreases the risk of secondary injuries (Aach et al. 2013,2014; Asselin et al.
2015; Hartigan et al. 2015; Kolakowsky-Hayner et al. 2013; Raab et al. 2016;
Strausser et al. 2010; Zeilig et al. 2012), as well as allowing restoration of a gait
pattern comparable to normal over ground walking (Esquenazi et al. 2012; Farris
et al. 2011; Spungen et al. 2013; Sylos-Labini et al. 2014). Among these positive
attributes, Benson et al. (2016) stressed a negative one, claiming that the use of
exoskeleton is characterized by the presence of a high rate of skin aberrations
In addition to the advantages pointed out by the literature review, we found that
the exoskeleton can be considered as an ecological device, replacing wheelchairs for
many hours at a time; it enables patients who cannot walk to regain a degree of
walking mobility and to retard the onset of a wide range of secondary disabilities
associated with the long-term use of wheelchairs. The exoskeleton can improve the
autonomy of the patient, who is enabled to walk independently, simply by wearing
it. No other rehabilitative or therapeutic techniques and technologies provide such an
extraordinary potential for autonomy.
Nevertheless, there are still some limitations in the rehabilitative use of an
exoskeleton. First, the wearability criteria are too restrictive; its use is limited to
people with specic values of height and weight (Esquenazi et al. 2012; Nilsson et al.
2014; Spungen et al. 2013; Sylos-Labini et al. 2014). Second, it requires very
complex and specialized training to use the exoskeleton autonomously at home.
Third, it is still an extremely expensive device, hardly covered by private or public
healthcare systems. For instance, the National Health Services in Europe generally
support the use of the exoskeleton for a rehabilitation program in specialized medical
centers, but never for a private individuals use at home or in the workplace. A nal
limitation is the scarcity of experimental designs based on evidence that demon-
strates the effectiveness of the exoskeleton compared to other rehabilitative tech-
niques and technologies. Only two studies that adopted a randomized clinical trial
design compared exoskeleton use to conventional gait training (Stein et al. 2014;
Watanabe et al. 2014); furthermore, the results of these two studies are contradictory.
Finally, user experience with an exoskeleton in daily life activities generally did not
meet subjectsexpectations in terms of perceived benets and impact on quality of
life (Benson et al. 2016).
Cross-References
Brain Computer Interface Assisted Gait
Gait Initiation, Turning, and Slopes
Gait Retraining for Balance Improvement
Measures to Determine Dynamic Balance
Slip and Fall Risk Assessment
Gait Rehabilitation with Exoskeletons 33
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Chapter
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Training leads to increased neuronal excitability, decreased inhibition and different types of neuronal plasticity. Most studies focus on cortical plastic changes after cerebral lesions or in healthy humans. In this study, we investigate cortical excitability and plastic changes after a three month period of HAL® exoskeleton supported treadmill training in patients with chronic incomplete spinal cord injury by means of electrophysiological measurements and functional magnetic resonance imaging. Here we report preliminary results of four patients.
Article
Full-text available
Stroke significantly affects thousands of individuals annually, leading to considerable physical impairment and functional disability. Gait is one of the most important activities of daily living affected in stroke survivors. Recent technological developments in powered robotics exoskeletons can create powerful adjunctive tools for rehabilitation and potentially accelerate functional recovery. Here, we present the development and evaluation of a novel lower limb robotic exoskeleton, namely H2 (Technaid S.L., Spain), for gait rehabilitation in stroke survivors. H2 has six actuated joints and is designed to allow intensive overground gait training. An assistive gait control algorithm was developed to create a force field along a desired trajectory, only applying torque when patients deviate from the prescribed movement pattern. The device was evaluated in 3 hemiparetic stroke patients across 4 weeks of training per individual (approximately 12 sessions). The study was approved by the Institutional Review Board at the University of Houston. The main objective of this initial pre-clinical study was to evaluate the safety and usability of the exoskeleton. A Likert scale was used to measure patient's perception about the easy of use of the device. Three stroke patients completed the study. The training was well tolerated and no adverse events occurred. Early findings demonstrate that H2 appears to be safe and easy to use in the participants of this study. The overground training environment employed as a means to enhance active patient engagement proved to be challenging and exciting for patients. These results are promising and encourage future rehabilitation training with a larger cohort of patients. The developed exoskeleton enables longitudinal overground training of walking in hemiparetic patients after stroke. The system is robust and safe when applied to assist a stroke patient performing an overground walking task. Such device opens the opportunity to study means to optimize a rehabilitation treatment that can be customized for individuals. This study was registered at ClinicalTrials.gov ( https://clinicaltrials.gov/show/NCT02114450 ).
Chapter
Rehabilitation robots have become an important tool in stroke rehabilitation. Compared to manual arm therapy, robot-supported arm therapy can be more intensive, with more frequent, more numerous, and longer repetitions. Therefore, robots have the potential to improve the rehabilitation process in stroke patients. In this chapter, the three-dimensional, multi-degree-of-freedom ARMin arm robot is presented. The device has an exoskeleton structure that enables the training of activities of daily living. Patient-responsive control strategies assist the patient only as much as needed and stimulate patient activity. This chapter covers the mechanical setup, the therapy modes, and the clinical evaluation of the ARMin robot. It concludes with an outlook on technical developments and about the technology transfer to industry.
Chapter
Treadmill training after traumatic spinal cord injury is established as a therapy to improve walking capabilities in incomplete injured patients. In this study we investigate walking capabilities after a three month period of HAL® exoskeleton supported treadmill training in patients with chronic (>6 month) complete/incomplete (ASIA A – ASIA C) spinal cord injury. We monitored walking distance, walking speed and walking time with additional analysis of functional improvement by using the 10-m-walk test, the timed-up-and-go test and the WISCI II score in combination with the ASIA classification.
Article
It is a single case study. An investigation to what extent the quality of life (QoL) of patients with spinal cord injury can be influenced by the training with an exoskeleton. The study was carried out at a Hospital for neurological rehabilitation, Germany. One patient (male, 22 years), initially unable to walk independently after traumatic spinal cord injury with neurological level Th11 (ASIA Impairment Scale C) was recruited for this study 1 year after injury. The progress of the first 6 months of ReWalk training was documented and as primary outcome measure the QoL was measured with SF-36 questionnaire. Secondary outcome measures were ASIA scale, Berg-Balance-Scale and Dynamic Gait Index. At the end of the studyperiod the patient was able to walk independently supervised by one person. QoL, mobility, risk of falling, motor skills and control of bladder and bowel functions were improved. A positive effect of robot-assisted gait training on various areas of the QoL was shown. Subsequent studies should aim to verify this effect through a higher number of patients and to different injury levels.
Article
The purpose of this methodological study was to evaluate the reliability, internal consistency, and sensitivity of a new self-report functional outcomes profile, the California Functional Evaluation 40 (CAFE 40). The CAFE 40 contains 3 sections: 1. Section 1 General health and activity level rated on an ordinal scale; 2. Section II: Independence- assistance needed rated on an ordinal scale; and 3. Section III: Endurance (specific listing of the patient reported amount of time that can be spent at a specific task such as walking, sitting, writing). In this study, Sections I and II were evaluated. Section III was rarely completed by the patients or normal subjects. 38 patients from 5 physical therapy outpatient clinics and 64 healthy adults participated in the reliability study by completing the functional profile twice within a 2 day interval. Test-retest reliability for the total profile score was high (r(lc) = 0.971). Internal consistency (the correlation between each item and the total section score reaching 0.5 or better) was acceptable for all but one item each in Section I and II (with the Spearman Rank Correlation Coefficient ranging from 0.408 to 0.82 in Section I and 0.463 to 0.748 in Section II). 45 patients participated in tile sensitivity study where the subjects completed the CAFE 40 at each physical therapy visit. A significant positive linear trend of improvement was noted (p < 0.001, Page Test). The last score was significantly higher than the first score for both Section I and II (p < 0.001 respectively as measured by Paired Wilcoxon Test). The results indicate that Sections I and II of the CAFE 40, have acceptable reliability, internal consistency, and sensitivity for measuring functional outcomes in healthy adults and patients receiving outpatient physical therapy. A revised profile is currently available for continued test development and broader application. Professionals in rehabilitation are encouraged to use this functional outcomes tool in their outpatient practices and send comments to the California Research Special Interest Group for continued improvement in the questionnaire.
Chapter
Rehabilitation robots have become an important tool in stroke rehabilitation. Compared to manual arm therapy, robot-supported arm therapy can be more intensive, of longer duration, and more repetitive. Therefore, robots have the potential to improve the rehabilitation process in stroke patients. In this chapter, the three-dimensional, multi-degree-of-freedom ARMin arm robot is presented. The device has an exoskeleton structure that enables the training of activities of daily living. Patient-responsive control strategies assist the patient only as much as needed and stimulate patient activity. This chapter covers the mechanical setup, the therapy modes, and the clinical evaluation of the ARMin robot. It concludes with an outlook on technical developments and about the technology transfer to industry.