Clinical effectiveness and safety of powered exoskeleton-assisted walking in patients with spinal cord injury: systematic review with meta-analysis

Figures & data

Table 1 MEDLINE search strategy

Diagnostic search terms

1. Paralysis

2. Paraplegi*

3. Spinal cord injury

4. SCI

5. Tetraplegi*

Therapeutic search terms

6. Argo

7. Bionic

8. Ekso

9. eLegs

10. Exoskeleton

11. H2

12. Indego

13. Mina

14. Mindwalker

15. Powered

16. ReWalk

17. REX

18. Robot*

19. WPAL

Combination terms

20. or/1–5

21. or/6–19

22. and/20–21

Note:

* Represents a wildcard symbol used in a search query to represent end truncation.

Figure 1 PRISMA flow diagram.

Abbreviation: PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Table 2 Baseline patient characteristics

Study	N	Male (n)	Age (years)	Height (cm)	Weight (kg)	BMI (kg/m^2)	LOI*	AIS			Time post-injury (years)
								A	B	C
Arazpour et al^Citation21	5	3	27	167	58	21	T6-T12	1	4	0	2.0
Asselin et al^Citation22	8	7	46	–	78	–	T1-T11	7	1	0	5.9
Benson et al^Citation23	10	10	32	–	–	–	C7-L1	7	0	3	4.8
Esquenazi et al^Citation24	12	8	38	177	74	23	T3-T12	–	–	–	7.4
Evans et al^Citation25	5	4	42	180	70	21	T6-T12	5	0	0	11.0
Fineberg et al^Citation26	6	5	45	174	71	23	T1-T11	5	1	0	6.3
Hartigan et al^Citation27	16	13	36	177	75	24	C5-L1	–	–	–	–
Kolakowsky-Hayner et al^Citation28	7	5	30	–	–	–	T4-T11	7	0	0	0.9
Kozlowski et al^Citation29	7	7	36	178	82	24	C4-L1	3	1	3	0.5
Kressler et al^Citation30	3	2	30	177	75	24	T1-T9	3	0	0	–
Spungen et al^Citation31	7	6	44	175	73	24	T1-T11	5	2	0	5.6
Talaty et al^Citation32	12	–	–	–	–	–	C7–T12	–	–	–	–
Yang et al^Citation33	12	10	46	173	75	25	C8-T11	9	2	1	6.8
Zeilig et al^Citation34	6	6	33	–	–	–	T5-T12	–	–	–	5.0

Notes:

* Represents the cephalad to caudal range. Dash indicates unspecified.

Abbreviations: AIS, American Spinal Injury Association Impairment Scale; BMI, body mass index; LOI, level of injury.

Table 3 Powered exoskeleton training protocols

Study	Study design	Exoskeleton	Training environment					Training volume
			Indoor walking	Outdoor walking	Obstacles	Stairs	ADLs	No of sessions	Session Length (min)	Sessions per week	Program duration (weeks)
Arazpour et al^Citation21	RCT	–	X					24	120	3	8
Asselin et al^Citation22	PCS	ReWalk	X					37	[75]	3	12
Benson et al^Citation23	PCS	ReWalk	X	X	X	Xa	Xb	20	120	2	10
Esquenazi et al^Citation24	PCS	ReWalk	X					24	[83]	3	8
Evans et al^Citation25	PCS	Indego	X					6	–	–	–
Fineberg et al^Citation26	PCS	ReWalk	X					[72]	[90]	3	24
Hartigan et al^Citation27	PCS	Indego	X	Xc	Xd		Xe	5	90	5	1
Kolakowsky-Hayner et al^Citation28	PCS	Ekso	Xf					6	58	1	6
Kozlowski et al^Citation29	PCS	Ekso	X		Xg		Xh	19	120	[1.5]	[13]
Kressler et al^Citation30	PCS	Ekso	Xf					18	60	3	6
Spungen et al^Citation31	PCS	ReWalk	X	Xi	Xj	Xb	Xk	45	[90]	3	[15]
Talaty et al^Citation32	PCS	ReWalk	X					24	[75]	3	8
Yang et al^Citation33	PCS	ReWalk	X					55	90	–	–
Zeilig et al^Citation34	PCS	ReWalk	X					14	50	–	–

Notes: Brackets represent an estimate. Dash indicates unspecified, blank spaces indicate not utilized.

a Includes walking up and down stairs;

b includes visiting a café, upright cooking, shopping;

c includes concrete walkway, city sidewalks, and grass;

d includes ramps with slope ≤5°;

e includes entering an elevator, riding to another floor, and exit without requiring the elevator door to be held open;

f includes tethered indoor walking;

g includes walking on carpet, rough concrete surfaces, and ramps with slope ≤8°;

h includes opening doors, pushing button to summon, enter, and exit elevators, and standing at counter and retrieve an item from high cupboard;

i includes walking on concrete and uneven ground surfaces;

j includes walking on carpet, up and down a slight slope, and up and down a curb;

k includes navigating a push button electric door, an elevator, and a revolving door.

Abbreviations: ADLs, activities of daily living; PCS, prospective case series; RCT, randomized controlled trial; min, minutes.

Figure 2 Ability to ambulate using a powered exoskeleton without physical assistance.

Notes: Data represent the proportion of subjects who were able to ambulate using an exoskeleton without physical assistance at the end of the training period. Fixed effects estimates: 76.2% (95% CI: 66.7%–84.1%); random effects estimates: 76.2% (95% CI: 58.6%–90.1%); I²=73%, P<0.001.
Abbreviation: CI, confidence interval.

Figure 3 Outcomes of randomized controlled trial comparing powered exoskeleton, reciprocating gait orthosis, and hip-knee-ankle-foot orthosis.

Notes: A is PCI, B is 6-min walk distance, and C is walking velocity. *Exoskeleton outcomes superior to RGO and HKAFO for walking velocity (both P<0.001), 6-minute walk distance (P=0.03 vs RGO; P<0.01 vs HKAFO), and PCI (both P<0.001).

Abbreviations: HKAFO, hip-knee-ankle-foot orthosis; PCI, physiological cost index; RGO, reciprocating gait orthosis.

Figure 4 Six-minute walk test results with a powered exoskeleton.

Notes: Data represent the number of meters walked with exoskeleton at the end of the training period. Fixed effects estimates: 99 m (95% CI: 92–106 m); random effects estimates: 98 m (95% CI: 80–117 m); I²=85%, P<0.001.
Abbreviation: CI, confidence interval.

Figure 5 Metabolic equivalents with powered exoskeleton walking.

Notes: Data represent the number of metabolic equivalents (METs) required for exoskeleton walking at the end of the training period. METs were calculated as 1 MET per 2.7 mL O₂/kg based on the estimated or measured maximal aerobic capacity values, unless otherwise specified. Fixed effects estimates: 3.9 METs (95% CI: 3.8, 4.0 METs); random effects estimates: 3.3 METs (95% CI: 2.2, 4.4 METs); I²=98%, P<0.001.
Abbreviation: CI, confidence interval.

Figure 6 Rating of perceived exertion with powered exoskeleton walking.

Notes: Data represent subjective rating of perceived exertion (RPE; Borg 6–20 scale) required for exoskeleton walking at the end of the training period. Fixed and random effects estimates: 10.1 (95% CI: 9.0, 11.3); I²=0%, P=0.97.
Abbreviations: CI, confidence interval; RPE, rating of perceived exertion.

Figure 7 Spasticity decreases with powered exoskeleton training.

Notes: Data represent the proportion of subjects who reported decreases in spasticity with exoskeleton training. Fixed effects estimates: 36.7% (95% CI: 21.9%, 53.6%); random effects estimates: 37.7% (95% CI: 18.5%, 59.2%); I²=46%, P=0.12.
Abbreviation: CI, confidence interval.

Figure 8 Improvements in bowel movement regularity with powered exoskeleton training.

Notes: Data represent the proportion of subjects who reported improvements in bowel movement regularity with exoskeleton training. Fixed effects estimates: 57.7% (95% CI: 37.3%, 76.3%); random effects estimates: 60.9% (95% CI: 19.5%, 94.5%); I²=81%, P<0.01.
Abbreviation: CI, confidence interval.

Figure 9 Incidence of falls with a powered exoskeleton.

Notes: Data represent the proportion of subjects who experienced a fall at any point during the training period. Fixed effects estimates: 4.3% (95% CI: 1.1%, 10.8%); random effects estimates: 4.4% (95% CI: 1.0%, 10.0%); I²=11%, P=0.34.
Abbreviation: CI, confidence interval.

Figure 10 Incidence of fractures with a powered exoskeleton.

Notes: Data represent the proportion of subjects who experienced a bone fracture at any point during the training period. Fixed effects estimates: 3.4% (95% CI: 0.7%, 9.5%); random effects estimates: 3.4% (95% CI: 0.7%, 8.1%); I²=0%, P=0.98.
Abbreviation: CI, confidence interval.

HigginsJPThompsonSGDeeksJJAltmanDGMeasuring inconsistency in meta-analysesBMJ2003327741455756012958120

 PubMed Web of Science ®Google Scholar

ArazpourMBaniMAHutchinsSWJonesRKThe physiological cost index of walking with mechanical and powered gait orthosis in patients with spinal cord injurySpinal Cord201351535635923247013

 PubMed Web of Science ®Google Scholar

AsselinPKnezevicSKornfeldSHeart rate and oxygen demand of powered exoskeleton-assisted walking in persons with paraplegiaJ Rehabil Res Dev201552214715826230182

 PubMedGoogle Scholar

BensonIHartKTusslerDvan MiddendorpJJLower-limb exoskeletons for individuals with chronic spinal cord injury: findings from a feasibility studyClin Rehabil2016301738425761635

 PubMed Web of Science ®Google Scholar

EsquenaziATalatyMPackelASaulinoMThe ReWalk powered exoskeleton to restore ambulatory function to individuals with thoracic-level motor-complete spinal cord injuryAm J Phys Med Rehabil2012911191192123085703

 PubMed Web of Science ®Google Scholar

EvansNHartiganCKandilakisCPharoEClessonIAcute cardiorespiratory and metabolic responses during exoskeleton-assisted walking overground among persons with chronic spinal cord injuryTop Spinal Cord Inj Rehabil201521212213226364281

 PubMedGoogle Scholar

FinebergDBAsselinPHarelNYVertical ground reaction force-based analysis of powered exoskeleton-assisted walking in persons with motor-complete paraplegiaJ Spinal Cord Med201336431332123820147

 PubMed Web of Science ®Google Scholar

HartiganCKandilakisCDalleySMobility outcomes following five training sessions with a powered exoskeletonTop Spinal Cord Inj Rehabil2015212939926364278

 PubMedGoogle Scholar

Kolakowsky-HaynerSACrewJMoranSShahASafety and feasibility of using the Ekso bionic exosksleton to aid ambulation after spinal cord injuryJ Spine2013S4003

 Google Scholar

KozlowskiAJBryceTNDijkersMPTime and effort required by persons with spinal cord injury to learn to use a powered exoskeleton for assisted walkingTop Spinal Cord Inj Rehabil201521211012126364280

 PubMedGoogle Scholar

KresslerJThomasCKField-FoteECUnderstanding therapeutic benefits of overground bionic ambulation: exploratory case series in persons with chronic, complete spinal cord injuryArch Phys Med Rehabil201495101878.e41887.e424845221

 PubMed Web of Science ®Google Scholar

SpungenAMAsselinPKFinebergDBKornfeldSDHarelNYExoskeletal-assisted walking for persons with motor-complete paraplegiaPaper presented at: NATO Science and Technology OrganizationMilan, ItalyApril 15–17, 2013

 Google Scholar

TalatyMEsquenaziABricenoJEDifferentiating ability in users of the ReWalk(TM) powered exoskeleton: an analysis of walking kinematicsIEEE Int Conf Rehabil Robot20132013665046924187286

 PubMedGoogle Scholar

YangAAsselinPKnezevicSKornfeldSSpungenAMAssessment of in-hospital walking velocity and level of assistance in a powered exoskeleton in persons with spinal cord injuryTop Spinal Cord Inj Rehabil201521210010926364279

 PubMedGoogle Scholar