Prosthetics and Orthotics International 1 –13© The International Society forProsthetics and Orthotics 2015Reprints and permissions: sagepub.co.uk/journalsPermissions.navDOI: 10.1177/0309364615588346poi.sagepub.com

INTERNATIONALSOCIETY FOR PROSTHETICSAND ORTHOTICS

Background

Knee–ankle–foot orthoses (KAFOs) are lower extrem-ity devices which extend over the knee, ankle, and foot. KAFOs are prescribed for people with lower limb mus-cle weakness; particularly in quadriceps muscles.1–3 KAFOs are prescribed for varying muscular weakness of the lower limb including poliomyelitis, post-polio syndrome, cerebrovascular accident (CVA), cerebral palsy (CP), spinal cord injury (SCI), and multiple scle-rosis (MS) to provide stability of the lower limb during locomotion.2 Lower limb weakness, especially knee extensor weakness, is a condition that alters normal gait

The gait and energy efficiency of stance control knee–ankle–foot orthoses: A literature review

Masoud Rafiaei1, Mahmood Bahramizadeh1, Mokhtar Arazpour1,2, Mohammad Samadian3, Stephen W Hutchins4 Farzam Farahmand5 and Mohammad A Mardani1

AbstractBackground: The use of knee–ankle–foot orthoses with drop locked knee joints produces some limitations for walking in subjects with quadriceps muscle weakness. The development of stance control orthoses can potentially improve their functionality.Objectives: The aim of this review was to compare the evidence of the effect of stance control orthoses to knee–ankle–foot orthoses with drop locked knee joints in improving kinematic variables and energy efficiency of walking by subjects with quadriceps muscle weakness caused by different pathologies.Study design: Literature review.Methods: Based on selected keywords and their composition, a search was performed in Google Scholar, PubMed, ScienceDirect, and ISI Web of Knowledge databases. In total, 18 articles were finally chosen for review.Results: The results of this study demonstrated that this type of orthosis can improve the walking parameters of subjects with quadriceps muscle weakness and spinal cord injury patients when compared to a locked knee–ankle–foot orthosis.Conclusion: There is evidence to show that stance control orthosis designs improve the gait kinematics but not energetic of knee–ankle–foot orthosis users. Development of new designs of stance control orthoses to provide a more normal pattern of walking is still required.

Clinical relevanceStance control orthoses are a new generation of orthotic intervention that could potentially be significant in assisting to improve the gait kinematics by knee–ankle–foot orthosis users.

KeywordsStance control knee joint, knee–ankle–foot orthoses, gait analysis, energy consumption

Date received: 29 October 2014; accepted: 19 April 2015

1 Department of Orthotics and Prosthetics, University of Social Welfare and Rehabilitation Sciences, Tehran, Islamic Republic of Iran

2 Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran

3 Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Islamic Republic of Iran

4 IHSCR, Faculty of Health & Social Care, University of Salford, Salford, UK

5Mechanical Engineering Department, Sharif University of Technology, Tehran, Islamic Republic of Iran

Corresponding author:Mokhtar Arazpour, Department of Orthotics and Prosthetics, University of Social Welfare and Rehabilitation Sciences, Kodakyar st., Daneshjo Blvd., Evin, Tehran 1985713834, Iran. Email: M.Arazpour@yahoo.com

588346 POI0010.1177/0309364615588346Prosthetics and Orthotics InternationalArazpour et al.research-article2015

Literature Review

2 Prosthetics and Orthotics International

patterns,4 and this condition may result in decreased sta-bility during daily tasks.5

Conventional KAFOs provide stability during walking by locking the knee joint in a fully extended position dur-ing both stance and swing phases. This requires excessive energy consumption and induces abnormal gait events such as circumduction, hip hiking, and vaulting during gait.6,7 Walking with conventional KAFOs can also lead to premature exhaustion during ambulation, as well as lim-ited mobility, pain, and a decreased range of motion (ROM) in lower limb joints.3,8 It has been reported that using a conventional KAFO reduces gait efficiency by 24%, increases vertical displacement of the center of mass (COM) by up to 65%, and also increases energy expendi-ture.9 Due to these factors, the rejection rate of using KAFOs in patients with muscular weakness of the lower limb due to conditions such as poliomyelitis, post-polio syndrome, CVA, CP, SCI, and MS has been reported as being between 60% and 100%.9

Stance control KAFOs (SCKAFOs) are a new genera-tion of KAFO which have been developed to prevent knee flexion during stance phase and permit free knee motion during swing phase of gait.10 Mechanical SCKAFOs are usually activated by ankle ROM mechanisms or limb incli-nation. The UTX, stance control orthosis (SCO) knee joint, swing phase lock (SPL), Horton, Otto Bock Free Walk, and the Otto Bock Sensor Walk are all examples of SCKAFOs.8,11

Using a SCKAFO produces an increased acceptance rate for wearing orthoses by patients with poliomyelitis, CP, CVA, and leg muscle weakness because of the ability to control knee flexion in stance and the provision of free knee flexion during swing phase of gait.3,8,12 Studies have demonstrated that velocity, cadence, stride length, and step length can increase when walking with a SCKAFO versus a locked knee KAFO.2,3,8,12 Irby et al.11 reported that KAFO users showed improvements in velocity, cadence, and stride length after 6 months of walking with the dynamic knee brace system (DKBS). SCKAFOs improve gait by encouraging more normal gait patterns, improving mobility, reducing the energy cost of walking, and reduc-ing compensatory strategies that may lead to chronic pain and loss of motion.2,12–14

Unfortunately, current commercial SCKAFOs are often noisy, bulky, heavy, and expensive and in some cases are not effective in improving kinematic variables and energy

expenditure. Davis et al.12 reported that there was no dif-ference in the energy cost of walking or physiological cost index (PCI) between a SCO and walking with the locked knee joint orthosis. Bernhardt et al.1 reported that it was slightly more difficult to sit down and stand up with the new SCKAFO. Zissimopoulos et al.8 showed that differ-ences in oxygen cost could not be detected between the auto and locked modes of a SCKAFO. Only one study ana-lyzed the engineering structure of this type of orthosis.15 The effects on all walking parameters while using this type of orthosis in comparison to a conventional KAFO are not clear. Therefore, the aim of this literature review was to summarize the research on walking parameters while using these orthoses in various patient groups.

Research questions

Energy expenditure and kinematic variables were used as a framework to define the following research questions:

•• With regard to energy expenditure: do subjects with quadriceps muscle weakness caused by different pathologies achieve reduced energy expenditure immediately and over time when using SCKAFOs compared with conventional KAFOs?

•• With regard to kinematic variables: do persons with quadriceps muscle weakness caused by different pathologies achieve a higher speed of walking, cadence, step length, knee ROM, reduced pelvic obliquity, and vertical and lateral displacement immediately and over time when using SCKAFOs compared with conventional KAFOs?

Method

Search strategy

An extensive electronic search was carried out through internationally published scholarly articles in Google Scholar, PubMed, ScienceDirect, and ISI Web of Knowledge (from 1950 to 2013) with the selected key-words (Table 1): stance control knee joint orthosis, stance control knee ankle foot orthosis, energy consumption, and temporal spatial parameters. The aforementioned key-words were also searched in combination with lower limb weakness, poliomyelitis, post-polio syndrome, spinal cord

Table 1. Keywords and combinations of keywords used in the study based on population intervention comparison outcome method.

P: Population I: Intervention C: Comparison O: Outcome measure

Lower limb weakness, poliomyelitis, post-polio syndrome, SCI, MS, and CP

Stance control knee joint orthosis, SCKAFO

Conventional KAFOs

Energy consumption, speed of walking, cadence, step length, knee ROM, pelvic obliquity, vertical and lateral displacement

Rafiaei et al. 3

injury, multiple sclerosis, and cerebral palsy. Search by selected keywords was organized following the population intervention comparison outcome (PICO) model. In order to provide a specific selection of previous studies, differ-ent combinations of the topics can be made with the use of AND, OR, and NOT. To prepare a more accurate and com-prehensive search, the references of primary resultant arti-cles were also included to find more suitable articles. The strategy includes medical subject headings (MeSH) and text words.

The title and abstract of each individual study were screened by authors. The first criterion to select appropri-ate articles was whether the title has addressed the research questions of interest. The second step in acquiring propor-tional articles was performed based on the following criteria:

1. Studies which were considered for inclusion were randomized controlled trials (RCTs), case–control trials, cohort studies, case series studies, and sin-gle-case studies.

2. The article was written in English.3. The study evaluated motorized (powered) or

mechanical SCO using over training time in polio-myelitis subjects.

4. The study investigated individuals with a lower limb weakness (poliomyelitis, post-polio, and SCI) and able-bodied subjects.

5. The main outcome measures of the article were balance, gait, energy consumption, kinetics, kine-matics, and tempo-spatial parameters.

The PICO was used to define the included studies. Figure 1 depicts the article selection procedure utilized. Ultimately, 18 studies were included in the review. All the subjects in these studies were persons with polio, post-polio, SCI patients, and able-bodied subjects.

Results

Table 2 summarizes the characteristics (participants, parameters, procedure, and results) of studies which evalu-ated SCOs compared to KAFO when worn during ambulation.

Research question 1: the energy efficiency of SCKAFOs

Interestingly, only three studies evaluated energy con-sumption in non-disabled subjects, subjects with lower limb pathology, and a patient with post-poliomyelitis when using a SCO.8,11,13 A trend to improved energy efficiency has been demonstrated in two studies (0.447 beats/min in using a SCO compared to 0.554 beats/min in locked KAFO, and 0.21 beats/min in using SCO compared to

0.25 beats/min in locked KAFO).8,13 However, one study reported an increased PCI when using a SCO compared to a locked KAFO (0.70 beats/min compared to 0.65 beats/min, respectively).11

Research question 2: the kinematic efficiency of SCKAFOs

Speed of walking. Typical walking speed has been reported as being 1.3 m/s during normal walking in healthy sub-jects.16 When using a powered SCO, this can reduce to only 0.57 m/s.16 The mean of this variable has been shown to be 1.18,8 0.82,2 0.8,13 0.59,11 0.63,20 1.04,3 and 0.6117 in various subjects when using a non-powered SCO for ambulation. Only three studies demonstrated an increase in walking speed compared to walking with a locked KAFO,8,11,12 while five studies reported a reduction in this parameter when wearing a SCO.3,16,17,19,20 An improve-ment in walking velocity has also been reported when

Google scholar =17ISI Web of Knowledge =12

Pub Med =18Science direct =14

Total= 61

Screening articles basedon inclusion criteria

32 articles acceptedin

quality assessment of papers

18 accepted articlescarefully considered to

fulfill the criteria

Figure 1. The article selection procedure utilized in this study.

4 Prosthetics and Orthotics International

Tab

le 2

. T

he c

hara

cter

istic

s (p

artic

ipan

ts, p

aram

eter

s, p

roce

dure

, and

res

ults

) of

stu

dies

tha

t ev

alua

ted

the

stan

ce c

ontr

ol o

rtho

sis

on k

nee–

ankl

e–fo

ot o

rtho

sis

user

s.

Ref

.M

etho

dR

esul

ts

Par

tici

pant

sP

aram

eter

sP

roce

dure

Ara

zpou

r

et a

l. (2

013)

16

Five

hea

lthy

subj

ects

of

mea

n ag

e of

26

± 5

.6 ye

ars,

w

eigh

t of

66

± 3

.8 k

g, a

nd

heig

ht o

f 176

± 4

.6 cm

pa

rtic

ipat

ed in

thi

s st

udy.

Gai

t an

alys

is: h

oriz

onta

l an

d ve

rtic

al e

xcur

sion

s of

th

e hi

ps, m

axim

um k

nee

flexi

on a

ngle

, spa

tio-

tem

pora

l gai

t pa

ram

eter

s.

Late

ral a

nd v

ertic

al

com

pens

ator

y m

otio

n

Gai

t da

ta w

ere

acqu

ired

in a

mot

ion

anal

ysis

labo

rato

ry u

sing

a c

alib

rate

d si

x-ca

mer

a vi

deo-

base

d m

otio

n an

alys

is.

Wal

king

tri

als

wer

e ra

ndom

ly p

erfo

rmed

in

thr

ee t

est

cond

ition

s: n

orm

al w

alki

ng

with

out

an o

rtho

sis,

wal

king

with

a

conv

entio

nal K

AFO

uni

late

rally

, and

als

o w

ith a

new

pow

ered

KA

FO a

pplie

d to

th

e sa

me

leg.

The

mea

ns o

f wal

king

spe

ed (

conv

entio

nal

KA

FO =

0.7

8 ±

0.0

29 m

/s, n

ew p

ower

ed

KA

FO =

0.5

7 ±

0.0

34 m

/s),

cade

nce

(con

vent

iona

l K

AFO

= 8

1 ±

5 s

teps

/min

, new

pow

ered

K

AFO

= 6

8 ±

3 s

teps

/min

), an

d kn

ee fl

exio

n du

ring

sw

ing

(con

vent

iona

l KA

FO =

6.6

° ± 0

.89°

, ne

w p

ower

ed K

AFO

= 4

0.2°

± 1

.30°

) an

d st

ep

leng

th (

conv

entio

nal K

AFO

= 0

.57

± 0

.019

cm,

new

pow

ered

KA

FO =

0.5

0 ±

0.0

40 cm

) w

ere

all d

ecre

ased

. Lat

eral

com

pens

ator

y m

otio

ns

(con

vent

iona

l KA

FO =

8.2

± 0

.63

cm, n

ew p

ower

ed

KA

FO =

5.8

± 0

.22

cm)

and

vert

ical

com

pens

ator

y m

otio

ns (

conv

entio

nal K

AFO

= 9

.8 ±

0.5

5 cm

, new

po

wer

ed K

AFO

= 7

.1 ±

0.2

3 cm

) w

ere

incr

ease

d by

bo

th o

rtho

ses

com

pare

d to

nor

mal

wal

king

. Mor

e kn

ee

flexi

on w

as o

bser

ved

in b

oth

swin

g an

d st

ance

pha

ses

whe

n w

alki

ng w

ith t

he p

ower

ed K

AFO

com

pare

d to

th

e co

nven

tiona

l KA

FO.

Ara

zpou

r

et a

l. (2

013)

17A

54-

year

-old

mal

e su

bjec

t su

fferi

ng fr

om

polio

mye

litis

.

Spee

d of

wal

king

, ste

p le

ngth

, tot

al r

ange

of

late

ral c

ompe

nsat

ory

mot

ion,

tot

al r

ange

of

vert

ical

com

pens

ator

y m

otio

n w

ere

all e

valu

ated

.

A m

otio

n an

alys

is s

yste

m w

as u

sed

to c

olle

ct lo

wer

lim

b ki

nem

atic

s. T

he

pers

on w

ith p

olio

mye

litis

use

d th

e K

AFO

with

pow

ered

kne

e jo

ints

for

wal

king

the

rapy

and

gai

t tr

aini

ng.

Wal

king

spe

ed (

conv

entio

nal K

AFO

= 0

.85

± 0

.06

m/s

, ne

w p

ower

ed K

AFO

= 0

.61

± 0

.04

m/s

), st

ep

leng

th (

conv

entio

nal K

AFO

= 0

.66

± 0

.05

m, n

ew

pow

ered

KA

FO =

0.5

2 ±

0.0

3 m

), an

d ve

rtic

al

(con

vent

iona

l KA

FO =

9.8

± 0

.04

cm, n

ew p

ower

ed

KA

FO =

7.2

± 0

.02

cm)

and

hori

zont

al d

ispl

acem

ent

of t

he p

elvi

s (c

onve

ntio

nal K

AFO

= 8

.6 ±

0.0

6 cm

, ne

w p

ower

ed K

AFO

= 5

.8 ±

0.0

4 cm

) de

crea

sed

whe

n w

alki

ng w

ith t

he p

ower

ed S

CK

AFO

com

pare

d to

the

K

AFO

. Whe

n us

ing

the

pow

ered

SC

KA

FO, t

he k

nee

flexi

on a

chie

ved

duri

ng s

win

g an

d al

so t

he o

vera

ll pa

tter

n of

wal

king

mor

e cl

osel

y m

atch

ed w

ith t

hat

of

norm

al h

uman

wal

king

. The

red

uced

wal

king

spe

ed

may

hav

e ca

used

the

sm

alle

r co

mpe

nsat

ory

mot

ions

de

tect

ed w

hen

the

pow

ered

SC

KA

FO w

as u

sed

Rafiaei et al. 5

Ref

.M

etho

dR

esul

ts

Par

tici

pant

sP

aram

eter

sP

roce

dure

To

et a

l. (2

012)

18A

70-

kg m

an w

ith

T-9

, ASI

A A

cla

ss S

CI

cons

ente

d to

par

ticip

ate

in t

his

stud

y.

Spat

ial-t

empo

ral

and

kine

mat

ics

gait

para

met

ers.

A m

otio

n an

alys

is s

yste

m w

as u

sed.

T

he u

pper

lim

b lo

ads

appl

ied

to t

he

wal

ker

duri

ng g

ait

with

the

HN

P w

ere

com

pare

d w

ith t

hree

con

trol

cas

es:

wal

king

with

(a)

FN

S on

ly; (

b) IR

GO

on

ly, w

ith h

ips

reci

proc

ally

cou

pled

, kn

ees

lock

ed in

ext

ensi

on, a

nd a

nkle

s lo

cked

at

neut

ral;

and

(c)

IRG

O w

ith

hips

rec

ipro

cally

cou

pled

, kne

es fr

eed

(i.e.

, dro

p lo

cks

of t

he s

tand

ard

KA

FO

unla

tche

d), a

nkle

s lo

cked

at

neut

ral,

and

join

ts d

rive

n by

pre

prog

ram

med

mus

cle

stim

ulat

ion

patt

ern.

The

HN

P re

duce

d th

e av

erag

e ve

rtic

al u

pper

lim

b fo

rces

on

the

wal

king

aid

. The

HN

P w

as a

lso

capa

ble

of r

educ

ing

the

stim

ulat

ion

duty

cyc

le o

f the

kne

e ex

tens

or m

uscl

es. T

he a

dditi

onal

mas

s an

d in

tern

al

fric

tion

of t

he S

CK

M w

as s

how

n to

hav

e m

inim

al

effe

ct o

n kn

ee a

ngle

tra

ject

ory

duri

ng s

win

g. T

hese

re

sults

sho

w t

hat

the

HN

P ca

n si

gnifi

cant

ly r

educ

e th

e us

er’s

upp

er li

mb

load

ing

and

the

amou

nt o

f m

uscl

e st

imul

atio

n, p

oten

tially

ena

blin

g in

divi

dual

s w

ith

para

pleg

ia t

o w

alk

long

er d

ista

nces

and

with

less

effo

rt

than

with

eith

er b

raci

ng o

r FN

S al

one.

Bern

hard

t

et a

l. (2

011)

19N

ine

subj

ects

(7

mal

es,

2 fe

mal

es, a

vera

ge a

ge:

61 ±

9 ye

ars)

with

incl

usio

n bo

dy m

yosi

tis.

Kin

emat

ic p

aram

eter

s,

velo

city

, cad

ence

, and

st

ep w

idth

wer

e ev

alua

ted

in t

his

stud

y.

All

patie

nts

had

obje

ctiv

e te

stin

g of

th

eir

stre

ngth

and

gai

t an

d co

mpl

eted

a

ques

tionn

aire

at

base

line

in 6

mon

ths.

Su

bjec

ts w

ere

fitte

d w

ith a

Sen

sor

Wal

k (O

tto

Bock

Hea

lth C

are,

Min

neap

olis

, M

N)

SCO

by

a ce

rtifi

ed o

rtho

tist.

Gai

t w

as a

sses

sed

usin

g a

10-c

amer

a m

otio

n an

alys

is s

yste

m a

nd fo

ur fo

rce

plat

form

s.

Gai

t an

alys

is w

as p

erfo

rmed

bot

h w

ith

and

with

out

the

orth

osis

.

Vel

ocity

(p

= 0

.025

) an

d ca

denc

e (p

= 0

.007

) w

ere

low

er a

nd s

tep

wid

th w

as h

ighe

r (p

= 0

.035

) w

ith t

he

SCO

tha

n w

hen

usin

g an

alte

rnat

ive

orth

osis

. The

re

was

sig

nific

ant

diffe

renc

e (p

= 0

.021

) on

pea

k kn

ee

flexi

on b

etw

een

unbr

aced

con

ditio

n an

d w

alki

ng w

ith

SCO

(un

brac

ed =

74.

4°. S

CO

= 6

2.9°

), bu

t th

ere

was

no

sig

nific

ant

diffe

renc

e (p

= 0

.355

) be

twee

n un

brac

ed

cond

ition

and

wal

king

with

SC

O in

pea

k hi

p fle

xion

).

Dav

is e

t al

. (2

010)

12T

wen

ty-o

ne s

ubje

cts

(15

mal

es; 6

fem

ales

) w

ith w

eak

or a

bsen

t qu

adri

ceps

. The

ave

rage

ag

e w

as 5

3 +

15

year

s an

d bo

dy m

ass

indi

ces

(BM

Is)

rang

ed fr

om 1

9 to

40.

Spat

io-t

empo

ral,

kine

mat

ic, a

nd k

inet

ic

para

met

ers.

Com

pari

son

betw

een

novi

ce a

nd

expe

rien

ced

user

s th

at u

se D

KBS

, an

elec

trom

echa

nica

l rel

ease

, and

sen

sors

at

the

kne

e an

d fo

otpl

ate,

all

fit t

o a

conv

entio

nal K

AFO

. Obj

ectiv

e ga

it m

easu

rem

ents

wer

e ac

quir

ed w

ith

a m

otio

n an

alys

is s

yste

m u

tiliz

ing

10

infr

ared

cam

eras

.

Nov

ice

user

s de

mon

stra

ted

incr

ease

d ve

loci

ty (

from

55

.3 t

o 59

.0 m

/s)

and

cade

nce

(from

86.

3 to

99.

2 st

eps/

min

) w

hen

usin

g th

e D

KBS

ove

r th

e tr

aditi

onal

lock

ed

KA

FO. E

xper

ienc

ed K

AFO

use

rs t

ende

d to

hav

e re

duce

d ve

loci

ty a

nd c

aden

ce m

easu

res

whe

n us

ing

the

SCO

. Kne

e R

OM

was

sig

nific

antly

gre

ater

for

the

novi

ce g

roup

tha

n fo

r th

e ex

peri

ence

d gr

oup.

Pea

k kn

ee e

xten

sion

mom

ents

ten

ded

to b

e gr

eate

r fo

r th

e ex

peri

ence

d gr

oup.

Yak

imov

ich

et

al.

(200

6)20

Thr

ee m

ale

KA

FO u

sers

w

ith k

nee

exte

nsor

w

eakn

ess

(mea

n ag

e:

56.3

year

s).

Spat

io-t

empo

ral a

nd

kine

mat

ics.

Thr

ee w

alki

ng t

rial

s w

ere

perf

orm

ed

with

the

sub

ject

s’ c

urre

nt K

AFO

and

th

en t

he n

ew S

CK

AFO

(no

n-ra

ndom

ized

be

fore

-aft

er t

rial

). Su

bjec

ts c

ompl

eted

a

ques

tionn

aire

abo

ut t

he n

ew S

CK

AFO

an

d cu

rren

t K

AFO

.

Incr

ease

d kn

ee fl

exio

n du

ring

sw

ing

(KA

FO w

ith lo

cked

kn

ee jo

int =

7.9

° an

d SC

KA

FO =

29.

03°)

, a g

reat

er t

otal

kn

ee R

OM

in n

ew S

CK

AFO

use

rs a

nd im

prov

ed g

ait

kine

mat

ics

and

prov

ided

mor

e na

tura

l gai

t.

(Con

tinue

d)

Tab

le 2

. (C

ontin

ued)

6 Prosthetics and Orthotics International

Ref

.M

etho

dR

esul

ts

Par

tici

pant

sP

aram

eter

sP

roce

dure

Yak

imov

ich

et

al.

(200

6)14

Thr

ee h

ealth

y ad

ults

(m

ale;

age

, 35

.3 ±

19.

7 ye

ars)

and

th

ree

KA

FO u

sers

with

kn

ee e

xten

sor

wea

knes

s in

at

leas

t on

e lim

b (m

ale;

m

ean

age,

56.

3 ye

ars)

.

Kin

emat

ics:

kne

e fle

xion

an

d to

tal k

nee

RO

M,

pelv

ic o

bliq

uity

, and

hip

ab

duct

ion

angl

e.

Eval

uatio

n of

a n

ew e

lect

rom

echa

nica

l SC

KA

FO a

nd c

ompa

red

to t

heir

pr

escr

ibed

KA

FO d

urin

g ga

it.

KA

FO u

sers

had

a m

ean

incr

ease

in k

nee

flexi

on

of 2

1.1°

(SD

= 8

.2)

duri

ng s

win

g, a

nd a

gre

ater

tot

al

knee

RO

M w

hen

wal

king

with

the

new

SC

KA

FO

com

pare

d to

the

ir p

resc

ribe

d K

AFO

. Tw

o K

AFO

use

rs

expe

rien

ced

a re

duct

ion

in p

elvi

c ob

liqui

ty a

nd h

ip

abdu

ctio

n an

gle

abno

rmal

ities

whe

n w

alki

ng w

ith t

he

SCK

AFO

com

pare

d to

the

ir p

resc

ribe

d K

AFO

.

Hw

ang

et a

l. (2

008)

21

Four

fem

ale

polio

mye

litis

pa

tient

s w

ere

sele

cted

as

exp

erim

enta

l sub

ject

s.

The

ir m

ean

age,

hei

ght,

and

wei

ght

wer

e as

fo

llow

s: 3

7 ±

4.8

year

s,

159

± 6

.4 cm

, and

56

± 9

.7 k

g, r

espe

ctiv

ely

and

all s

ubje

cts

wer

e un

ilate

ral K

AFO

use

rs.

Spat

io-t

empo

ral

gait

para

met

ers

and

kine

mat

ics

incl

uded

: kn

ee fl

exio

n an

gles

. Tw

o fo

rce

plat

es w

ere

used

to

mea

sure

gro

und

reac

tion

forc

es.

A g

ait

anal

ysis

was

per

form

ed o

n ea

ch

subj

ect

usin

g a

thre

e-di

men

sion

al (

3-D

) m

otio

n an

alys

is s

yste

m w

ith s

ix in

frar

ed

cam

eras

and

tw

o fo

rce

plat

es in

ord

er

to c

ompa

re g

ait

patt

erns

in t

wo

orth

otic

co

nditi

ons:

an

elec

trom

echa

nica

l K

AFO

with

the

lock

ed k

nee

(wal

king

w

ith a

KA

FO w

ith t

he c

lutc

h lo

cked

ov

er t

he w

hole

per

iod

of t

he g

ait

cycl

e), a

nd c

ontr

olle

d kn

ee g

ait

(wal

king

with

a K

AFO

with

the

clu

tch

elec

trom

echa

nica

lly c

ontr

olle

d).

All

subj

ects

had

con

side

rabl

y hi

gher

max

imum

kne

e fle

xion

dur

ing

swin

g ph

ase

for

cont

rolle

d kn

ee g

ait

(lock

ed K

AFO

= 2

.9°

and

cont

rolle

d K

AFO

= 3

2.6°

). T

he

patt

ern

of p

elvi

c ob

liqui

ty d

urin

g co

ntro

lled

knee

gai

t w

as v

ery

sim

ilar

to n

orm

al g

ait,

but

ther

e w

ere

som

e de

viat

ions

. The

re w

ere

no s

igni

fican

t di

ffere

nces

in

hear

t ra

te a

nd m

inut

e ve

ntila

tion.

Thi

s re

sulte

d in

app

roxi

mat

ely

33%

less

ene

rgy

cons

umpt

ion

than

in lo

cked

kne

e ga

it. It

pro

vide

d bo

th

stab

ility

in t

he s

tanc

e an

d fr

ee s

win

ging

of t

he k

nee.

Ras

mus

sen

et

al.

(200

7)10

A

pat

ient

with

a T

10 S

CI

(30-

year

-old

man

)Sp

atio

-tem

pora

l gai

t pa

ram

eter

s.

Kin

emat

ic: t

runk

flex

ion/

exte

nsio

n, la

tera

l fle

xion

, an

d ro

tatio

n.

Excu

rsio

n, h

ip, a

nd k

nee

flexi

on/e

xten

sion

RO

M.

A 3

-D g

ait

anal

ysis

was

use

d.

The

aut

hors

rep

ort

the

use

of S

CK

AFO

s in

com

bina

tion

with

an

IRG

O. A

co

mpa

riso

n is

mad

e be

twee

n th

e sc

enar

ios

of h

avin

g th

e kn

ees

lock

ed

duri

ng t

he e

ntir

e ga

it cy

cle

to t

hat

of

allo

win

g th

e kn

ees

to fl

ex fr

eely

dur

ing

the

swin

g ph

ase,

yet

stil

l be

lock

ed fo

r st

abili

ty d

urin

g st

ance

.

The

add

ition

of s

tanc

e co

ntro

l to

an IR

GO

in t

his

subj

ect

doub

led

his

wal

king

spe

ed (

IRG

O w

ith lo

cked

kn

ee jo

ints

= 0

.11

± 0

.04

m/s

and

IRG

O w

ith S

C k

nee

join

ts =

0.2

3 ±

0.0

2 m

/s)

and

stri

de le

ngth

(IR

GO

with

lo

cked

kne

e jo

ints

= 0

.44

± 0

.27

m a

nd IR

GO

with

SC

kn

ee jo

ints

= 0

.92

± 0

.05

m)

with

a s

light

red

uctio

n in

ca

denc

e (IR

GO

with

lock

ed k

nee

join

ts =

38.

4 ±

17.

6 st

eps/

min

and

IRG

O w

ith S

C k

nee

join

ts =

30.

37 ±

1.3

2 st

eps/

min

) so

tha

t th

is is

mor

e in

line

with

the

leng

th o

f hi

s st

ride

s. T

he s

ubje

ct a

mbu

late

d w

ith a

fast

er, m

ore

effic

ient

gai

t pa

tter

n w

ith t

he s

tanc

e co

ntro

l fea

ture

ac

tivat

ed. T

his

orth

otic

opt

ion

affo

rded

him

the

abi

lity

to w

alk

safe

ly a

nd s

moo

thly

with

bot

h kn

ees

flexi

ng

duri

ng s

win

g an

d w

ith le

ss u

pper

bod

y co

mpe

nsat

ion.

Tab

le 2

. (C

ontin

ued)

Rafiaei et al. 7

Ref

.M

etho

dR

esul

ts

Par

tici

pant

sP

aram

eter

sP

roce

dure

Zis

sim

opou

los

et a

l. (2

007)

8

Nin

e ab

le-b

odie

d (fi

ve

fem

ales

and

four

mal

es).

Subj

ects

had

a m

ean

age

25 ±

2 ye

ars.

Spat

io-t

empo

ral d

ata.

Kin

emat

ic d

ata:

ank

le

dors

iflex

ion,

kne

e fle

xion

, an

d pe

lvic

obl

iqui

ty.

Ener

gy e

xpen

ditu

re

para

met

ers.

Subj

ects

wal

ked

with

KA

FOs

that

in

corp

orat

ed t

he H

orto

ns s

tanc

e co

ntro

l ort

hotic

kne

e jo

int

(SC

OK

J) in

th

e lo

cked

, unl

ocke

d, a

nd a

uto

mod

es

to in

vest

igat

e th

e bi

omec

hani

cal a

nd

ener

getic

effe

cts

of S

CO

s. T

he s

tudy

co

nsis

ted

of t

hree

sta

ges:

fabr

icat

ion,

dy

nam

ic a

djus

tmen

t an

d tr

aini

ng,

and

data

col

lect

ion.

For

the

ene

rgy

expe

nditu

re e

valu

atio

n, d

ata

wer

e co

llect

ed w

ith a

Cos

med

K4b

2 po

rtab

le

spir

omet

er o

n tr

eadm

ill. G

ait

anal

ysis

da

ta w

ere

proc

esse

d w

ith m

otio

n an

alys

is s

yste

m.

Gai

t ki

nem

atic

s fo

r th

e au

to a

nd u

nloc

ked

mod

es w

ere

mor

e si

mila

r th

an fo

r th

e au

to a

nd lo

cked

mod

es.

Oxy

gen

cost

was

not

diff

eren

t be

twee

n th

e au

to a

nd

lock

ed m

odes

(p

> 0

.99)

.

Irby

et

al.

(200

7)2

14 r

esea

rch

part

icip

ants

(1

1 m

ales

; 3 fe

mal

es).

Nin

e re

sear

ch p

artic

ipan

ts

had

polio

whi

le t

he

rem

aini

ng p

atie

nts

had

othe

r pa

thol

ogie

s or

tra

uma

incl

udin

g ne

urop

athi

es, i

ncom

plet

e SC

Is, s

pina

bifi

da, M

S,

and

mus

cula

r dy

stro

phy.

A

vera

ge a

ge w

as

51 +

17

year

s.

Spat

io-t

empo

ral

kine

mat

ics:

pel

vic

obliq

uity

, hip

flex

ion,

hi

p ex

tens

ion,

and

hip

ab

duct

ion.

Kin

etic

s: p

eak

cont

rala

tera

l hip

ab

duct

ion

in s

win

g an

d ip

sila

tera

l ext

ensi

on

mom

ents

dur

ing

stan

ce,

aver

age

knee

ext

enso

r m

omen

ts d

urin

g st

ance

, kn

ee m

omen

t at

foot

-off,

an

d pe

ak c

ontr

alat

eral

an

kle

plan

tarf

lexi

on

mom

ent

duri

ng s

tanc

e.

A m

otio

n an

alys

is s

yste

m (

DK

BS)

was

use

d du

ring

a p

rosp

ectiv

e op

en-

enro

llmen

t 6-

mon

th c

linic

al fi

eld

tria

l.

The

“ex

peri

ence

d” g

roup

rou

tinel

y us

ed

a lo

cked

KA

FO fo

r am

bula

tion.

The

“n

ovic

e” g

roup

had

bee

n pr

escr

ibed

but

di

d no

t re

gula

rly

use

a lo

cked

KA

FO fo

r am

bula

tion.

Wal

king

vel

ocity

(be

fore

= 7

9 ±

19

m/s

and

aft

er

6 m

onth

s = 8

2 ±

16

m/s

), ca

denc

e (b

efor

e =

78

± 1

3 st

eps/

min

and

aft

er 6

mon

ths =

83

± 8

ste

ps/m

in),

and

stri

de le

ngth

(be

fore

= 1

07 ±

18

cm a

nd a

fter

6

mon

ths =

117

± 1

5 cm

) in

crea

sed

at t

he in

itial

tes

t to

6

mon

ths.

Sing

le-li

mb

supp

ort

time

rem

aine

d un

chan

ged

thro

ugho

ut t

his

field

tri

al.

Res

ults

sho

wed

tha

t al

l sub

ject

s si

gnifi

cant

ly in

crea

sed

peak

kne

e fle

xion

bet

wee

n th

e in

itial

and

6-m

onth

tes

ts

(bef

ore

= 4

9.0

± 1

5.5°

and

aft

er 6

mon

ths =

55.

9° ±

11.

4°).

(Con

tinue

d)

Tab

le 2

. (C

ontin

ued)

8 Prosthetics and Orthotics International

Ref

.M

etho

dR

esul

ts

Par

tici

pant

sP

aram

eter

sP

roce

dure

Bern

hard

t et

al.

(200

6)1

20 s

ubje

cts

(14

mal

es; 6

fe

mal

es).

The

maj

ority

of

the

par

ticip

ants

w

ere

affe

cted

by

polio

(1

2/20

), bu

t di

agno

ses

also

incl

uded

inco

mpl

ete

SCI,

MS,

indu

stri

al o

r ot

her

inju

ry, s

pina

bifi

da,

mus

cula

r dy

stro

phy,

in

clus

ive

body

myo

sitis

, an

d w

eakn

ess

of u

nkno

wn

orig

in. T

he a

ge o

f the

re

sear

ch p

artic

ipan

ts

was

53.

2 +

14.

8 (r

ange

: 11

–76)

yea

rs, w

ith a

BM

I of 2

8.7

+ 6

.1 (

rang

e:

19.2

–40.

1.

Gai

t an

alys

is c

once

ntra

ted

on o

rtho

sis

activ

ities

suc

h as

don

ning

and

dof

fing

the

orth

osis

, ass

umin

g a

sitt

ing

or s

tand

ing

posi

tion,

us

e of

ass

istiv

e de

vice

s,

orth

osis

aes

thet

ics,

st

abili

ty d

urin

g w

alki

ng a

nd

stan

ding

, wal

king

abi

lity

over

dis

tanc

e an

d va

riou

s te

rrai

n, a

nd s

elf-r

epor

ted

daily

use

of t

he o

rtho

sis.

Ph

ysic

al e

xam

inat

ion

incl

udin

g bi

late

ral l

ower

lim

b st

reng

th a

nd R

OM

, an

d a

func

tiona

l 6-m

in

wal

k te

st.

Thi

s st

udy

was

a c

ompo

nent

of a

n ov

eral

l pro

ject

des

ign

incl

udin

g 6

mon

ths

at h

ome

field

tri

al o

f the

DK

BS, w

ith

labo

rato

ry t

estin

g at

tim

es 0

, 3, a

nd

6 m

onth

s. P

artic

ipan

ts w

ere

free

to

choo

se b

etw

een

the

DK

BS a

nd t

heir

pe

rson

al o

rtho

sis

duri

ng t

he t

rial

.

Stab

ility

whi

le s

tand

ing

and

wal

king

with

the

DK

BS w

as

rate

d as

acc

epta

ble

to e

xcel

lent

and

slig

htly

bet

ter

than

ot

her

brac

es. I

t w

as s

light

ly m

ore

diffi

cult

to s

it do

wn

and

stan

d up

with

the

DK

BS. T

his

stud

y sh

ows

that

w

eari

ng a

sta

nce

cont

rol k

nee

orth

osis

can

be

a po

sitiv

e ex

peri

ence

for

an o

rtho

sis

user

.

Ferr

is e

t al

. (2

006)

22A

71-

year

-old

pol

io

patie

nt.

Tem

pora

l and

spa

tial g

ait

char

acte

rist

ics

Thi

s ca

se s

tudy

out

lined

the

suc

cess

ful

pres

crip

tion

of a

KA

FO t

hat

inco

rpor

ated

a s

tanc

e co

ntro

l kne

e jo

int

(E-K

nee,

Bec

ker

Ort

hope

dic,

USA

).

Thi

s ca

se s

tudy

out

lined

the

suc

cess

ful p

resc

ript

ion

of

a K

AFO

tha

t in

corp

orat

ed a

sta

nce

cont

rol k

nee

join

t (E

-Kne

e, B

ecke

r O

rtho

pedi

c, U

SA).

It a

lso

outli

ned

how

th

e us

e of

ort

hotic

dia

gnos

tic t

ools

aid

pre

scri

ptio

n an

d de

mon

stra

te im

prov

emen

ts in

tem

pora

l and

spa

tial g

ait

char

acte

rist

ics

with

SC

KA

FO.

Irby

et

al.

(200

5)11

10 s

ubje

cts

(low

er li

mb

path

olog

y)En

ergy

exp

endi

ture

and

sp

atio

-tem

pora

l gai

t ch

arac

teri

stic

s w

ere

mea

sure

d in

thi

s st

udy.

A G

ait

Rite

wal

kway

was

use

d to

mea

sure

tem

poro

spat

ial g

ait

char

acte

rist

ics.

A C

osm

ed K

4b2

port

able

m

etab

olic

sys

tem

was

use

d to

mea

sure

en

ergy

exp

endi

ture

and

hea

rt r

ate

duri

ng w

alki

ng. T

wo

cond

ition

s w

ere

test

ed: w

alki

ng w

ith s

tanc

e co

ntro

l act

ive

(Hor

tons

SC

O)

and

wal

king

with

the

kn

ee jo

int

lock

ed.

Wal

king

vel

ocity

was

sig

nific

antly

incr

ease

d in

the

st

ance

con

trol

con

ditio

n (S

CK

AFO

= 7

2.9

± 2

5.7

cm/s

an

d lo

cked

KA

FO =

65.

0 ±

24.

5 cm

/s).

The

re

was

no

diffe

renc

e in

the

oxy

gen

cost

of w

alki

ng

(SC

KA

FO =

0.2

13 ±

0.0

81 m

L/kg

/min

and

lock

ed

KA

FO =

0.2

24 ±

0.0

69 m

L/kg

/min

) or

PC

I bet

wee

n co

nditi

ons

(SC

KA

FO =

0.6

5 ±

0.3

2 be

ats/

min

and

lock

ed

KA

FO =

0.7

0 ±

0.3

4 be

ats/

min

).

Yak

imov

ich

et

al.

(200

5)9

Thr

ee a

ble-

bodi

ed

subj

ects

and

thr

ee K

AFO

us

ers.

Kin

emat

ic g

ait

anal

ysis

.A

n ev

alua

tion

of a

n el

ectr

omec

hani

cal

SCK

AFO

con

duct

ed t

o de

term

ine

its

func

tiona

l and

clin

ical

effe

ctiv

enes

s du

ring

gai

t.

The

SC

KA

FO p

erm

itted

a m

ean

incr

ease

in s

agitt

al

knee

mot

ion

duri

ng s

win

g fo

r th

e th

ree

KA

FO u

sers

an

d a

redu

ctio

n in

pel

vic

obliq

uity

and

hip

abd

uctio

n an

gle

abno

rmal

ities

dur

ing

term

inal

sta

nce

and

swin

g fo

r tw

o K

AFO

use

rs.

Tab

le 2

. (C

ontin

ued)

Rafiaei et al. 9

Ref

.M

etho

dR

esul

ts

Par

tici

pant

sP

aram

eter

sP

roce

dure

Heb

ert

and

Ligg

ins

(200

5)13

A 6

1-ye

ar-o

ld m

ale

volu

ntee

r w

ith p

ost-

polio

mye

litis

Kin

emat

ic a

nd k

inet

ic

gait

anal

yses

and

PC

I in

the

lock

ed k

nee

and

stan

ce c

ontr

ol m

odes

. El

ectr

omyo

grap

hic

data

w

ere

reco

rded

from

the

no

n-br

aced

lim

b on

ly b

y us

ing

a su

rfac

e el

ectr

ode

syst

em.

The

sub

ject

was

fitt

ed w

ith a

rig

ht

KA

FO w

ith a

n au

tom

atic

Hor

tons

sta

nce

cont

rol k

nee

join

t th

at a

llow

ed fr

ee

flexi

on o

f the

kne

e in

the

sw

ing

phas

e,

with

aut

omat

ic lo

ckin

g of

the

kne

e at

the

in

itiat

ion

of s

tanc

e ph

ase.

Inst

rum

ente

d ga

it an

alys

is w

as c

ondu

cted

6 m

onth

s af

ter

the

patie

nt r

ecei

ved

the

new

K

AFO

. All

data

typ

es w

ere

reco

rded

si

mul

tane

ousl

y du

ring

eac

h of

tw

o am

bula

tory

con

ditio

ns: w

alki

ng w

ith t

he

brac

e in

lock

ed k

nee

mod

e an

d th

en in

au

tom

atic

sta

nce

cont

rol m

ode.

Impr

oved

gai

t bi

omec

hani

cs in

use

of s

tanc

e co

ntro

l m

ode

com

pare

d w

ith a

lock

ed m

ode.

The

re w

as a

tr

end

tow

ard

impr

oved

ene

rgy

effic

ienc

y in

the

sta

nce

cont

rol m

ode

vers

us t

he lo

cked

kne

e m

ode.

McM

illan

et

al.

(200

4)3

Thr

ee s

ubje

cts

with

lo

wer

lim

b w

eakn

ess.

Su

bjec

t 1

was

a 5

6-ye

ar-

old

man

with

pos

t-po

lio

synd

rom

e w

ho h

ad w

orn

a K

AFO

with

the

SC

OK

J fo

r 2

year

s. S

ubje

ct 2

was

a

59-y

ear-

old

man

with

po

st-p

olio

syn

drom

e w

ho

had

wor

n th

e SC

OK

J K

AFO

for

6 w

eeks

and

Su

bjec

t 3

was

a 3

0-ye

ar-

old

mal

e w

ith a

ner

ve

root

inju

ry (

L4 le

vel)

seco

ndar

y to

tra

uma.

Spat

io-t

empo

ral

para

met

ers:

wal

king

sp

eed,

cad

ence

str

ide,

and

st

ep le

ngth

.

Kin

emat

ics:

kne

e fle

xion

/ex

tens

ion,

hip

, pel

vic,

and

tr

unk

mov

emen

t.

Hea

rt r

ate

All

thre

e su

bjec

ts c

ompl

eted

gai

t an

alys

is, t

hen

obst

acle

cou

rse

tria

ls, t

hen

trea

dmill

tri

als

with

in 1

day

, tak

ing

a br

eak

befo

re t

read

mill

tri

als

to r

est

and

eat

to d

eter

min

e w

heth

er in

divi

dual

s w

ith lo

wer

lim

b w

eakn

ess

wal

k m

ore

effic

ient

ly w

hen

usin

g th

e SC

OK

J tha

n w

hen

usin

g a

conv

entio

nal K

AFO

with

th

e kn

ee lo

cked

in e

xten

sion

.

Impr

oved

tem

poro

spat

ial p

aram

eter

s w

hen

wal

king

w

ith S

CO

KJ w

as n

oted

. Inc

reas

ed s

peed

and

ca

denc

e, in

crea

sed

stri

de a

nd s

tep

leng

ths,

and

few

er

com

pens

ator

y m

ovem

ents

at

the

hip,

pel

vis,

and

tru

nk

whe

n w

alki

ng w

ith t

he S

CO

KJ t

han

whe

n w

alki

ng

with

the

con

vent

iona

l KA

FO w

as n

oted

. Tw

o su

bjec

ts

show

ed lo

wer

ene

rgy

expe

nditu

re w

hen

wal

king

with

th

e SC

OK

J.

Tok

uhar

a

et a

l. (2

000)

23T

wo

post

-pol

io s

yndr

ome

patie

nts.

Sub

ject

1 (

S1)

was

a w

oman

(42

year

s ol

d). S

ubje

ct 2

(S2

) w

as a

m

ale

(46

year

s ol

d).

Kin

emat

ics:

ank

le a

nd

knee

join

t an

gles

, sha

nk

rate

vel

ocity

, foo

t ta

ngen

tial a

ccel

erat

ion,

an

d ac

tivat

ion

peri

od.

Each

KA

FO c

ould

be

adap

ted

to t

est

two

diffe

rent

con

ditio

ns: (

a) c

ontr

ol

by d

orsi

flexi

on (

CD

) an

d (2

) cy

clic

al

cont

rolle

r (C

C).

Five

wal

king

tri

als

(ass

iste

d by

cru

tche

s) t

hrou

gh a

10

m

path

wer

e pe

rfor

med

.

The

res

ults

from

imm

edia

te in

spec

tion

indi

cate

an

impo

rtan

t im

prov

emen

t of

the

gai

t pa

tter

ns (

knee

fle

xion

in s

win

g in

sub

ject

1 =

50°

± 3

° an

d in

sub

ject

2

= 6

1° ±

3°)

in t

wo

patie

nts

with

pro

xim

al le

g w

eakn

ess

by m

eans

of c

ompe

nsat

ions

app

lied

by t

he w

eara

ble

orth

osis

.

SCK

M: s

tanc

e co

ntro

l kne

e m

echa

nism

; FN

S: fu

nctio

nal n

euro

mus

cula

r st

imul

atio

n; H

NP:

hyb

rid

neur

opro

sthe

sis;

IRG

O: i

soce

ntri

c re

cipr

ocat

ing

gait

orth

osis

.

Tab

le 2

. (C

ontin

ued)

10 Prosthetics and Orthotics International

using a stance control knee joint compared to drop locked knee joint in wearing an RGO in SCI patients (0.12 and 0.23 m/s).10,18

Cadence. Six studies noted an increase in cadence during walking with a SCO compared to walking with locked KAFO.2,3,8,11,12,21 However, Hebert et al. when using an automatic SCO and Arazpour et al. when using a powered KAFO both detected a reduction in this parameter com-pared to walking with locked KAFOs.13,16 Using a SCO associated with an RGO caused a reduction in this param-eter in SCI patients.10 The mean cadence in these studies was between 53 and 102 steps/min.

Step length. Nine studies analyzed step length in various subjects (poliomyelitis subjects, SCI patients, other pathol-ogies, and able bodied) while walking with a SCO. An increase in this parameter was reported in three stud-ies.2,3,12 However, three studies reported reduction in this parameter when using a SCO compared to a locked KAFO.16,17,20 One study reported similar results when ‘using a joint that can be switched between locked knee and stance control modes’ (mean: 0.6 m),8 but a second study demonstrated a reduction in step length compared to a locked KAFO.13 The mean of step length reported in these studies was between 50 and 70 cm. Two studies using a SCO in combination with an RGO by SCI patients dem-onstrated the mean of this parameter to be 0.46 and 0.36 m.10,18

Knee ROM. The knee joint needs 67° of flexion during swing phase in healthy subjects during normal walk-ing.16 Using a SCO reduces this mean to 40° in healthy subjects.16 The reported mean of this parameter was 62.9°,1 47°,24 50°, 61°,21 and 43°25 when SCOs are used compared to KAFO with drop locked knee joints (2°–5°). The mean knee joint ROM during swing phase was 50° when walking with a SCO associated with an RGO in SCI subjects compared to RGO with drop locked knee joints.10

Pelvic obliquity. Pelvic obliquity was analyzed in three stud-ies when SCO was compared to KAFO with drop locked knee joint in able-bodied, poliomyelitis, and various sub-jects.2,8,14 Irby et al.2 in gait evaluation of SCOs by 14 SCO users during a 6-month clinical field trial announced that all subjects had significantly lower pelvic obliquity, 2.8 mm (p = 0.04) compared to baseline. Zissimopoulos et al.8 studied the biomechanical and energetic effects of a SCO knee joint on the gait of nine non-disabled persons and reported significant differences between the locked mode and unlocked mode (p = 0.003) and auto mode and locked mode (p = 0.01). Yakimovich et al. evaluated the kinematics of a new SCKAFO on three male KAFO users with knee extensor weakness. The new SCKAFO improved

pelvic obliquity and provided a more natural gait for ortho-sis users compared to conventional KAFOs.14

Vertical and lateral displacement. Reduction in the mean of lateral displacement has been reported when using SCO compared to locked KAFO. Arazpour et al.,16 in using a SCO in healthy subjects, demonstrated the decreased rate of this parameter from 8.2 to 5.8 mm. In other study, Arazpour et al.17 in evaluation of powered SCO on one poliomyelitis subject reported a reduction in lateral dis-placement from 8.6 to 5.8 mm. Hwang et al.21 in an evalu-ation of electromechanical SCOs worn by four poliomyelitis subjects demonstrated a reduction in this parameter from 292.8 to 196.7 mm.

Similar to lateral displacement, reduction in vertical displacement has been demonstrated when walking with a SCO compared to a locked KAFO in poliomyelitis sub-jects. Both Arazpour et al.17 and Hwang et al.21 reported a reduction in this parameter from 64.7 to 54.2 and from 9.8 to 7.2 mm, respectively. This reduction, in another study by Arazpour et al.,16 was confirmed on healthy subjects when using a SCO compared to locked KAFO (from 9.8 to 7.1 mm). The optimal level of this parameter was reported as being 4.7° for lateral displacement and 5° for vertical displacement.16

Discussion

The aim of this study was to evaluate the effect of SCO use on walking efficacy in users of this type of orthosis. Recommended indications are different for SCKAFOs compared to KAFOs. Subjects with lower limb weakness can use a KAFO with drop locked knee joints. Users who have sufficient hip strength can benefit from a SCKAFO, and the criterion for using a SCKAFO is the presence of hip strength of at least Grade 3. Impaired cognition, knee-flexion contracture >10°, moderate to severe spasticity of the hamstrings, lack of hip abductors in bilateral patients, uncorrectable genu varum/valgum >10°, lack of motiva-tion or inappropriate expectations, and body weight >300 lbs are all contraindications for using SCKAFOs.25

The provision of reduced energy consumption has been quoted as one of the main aims and reasons for subjects with lower limb weakness to walk with a SCO. Due to paralysis of the lower limb muscles, KAFO users are forced to walk with the knee in a locked position, hip hiking strat-egy, leg circumduction, or a vaulting gait.6,7 This can cause soft tissue injury, an increased effort to walk, and a high rate of energy consumption in KAFO users.3,8 Only three studies evaluated this parameter in poliomyelitis subjects when wearing SCO compared to a locked KAFO.8,12,13 Despite the advantages of walking with a SCO, this type of orthosis has not demonstrated a significant improvement by producing decreased energy consumption.8,13 It would be expected that based on the free swing in the knee joint

Rafiaei et al. 11

during swing phase made available by this device, the users effort would be decreased and therefore this would cause less energy consumption during ambulation. However, the number of participants was small, as few subjects partici-pated in these studies, so the results cannot be generalized for the larger population. More studies are therefore needed to further analyze this effect.

Increased knee joint flexion and extension during swing when walking with a SCO compared to a KAFO in sub-jects with lower limb paralysis is a positive function for such individuals. In using SCO, walking with the knee locked provides stance phase stability, but provides free flexion in swing phase during ambulation, and the devel-opment of the SCO was based on this concept. The knee joint must have approximately 70° of flexion available in normal walking, but SCOs have not demonstrated that they can provide this amount of flexion. Future designs of SCOs must consider this limitation by providing more knee joint flexion. In addition, stance phase flexion must be developed in new designs of SCO to provide flexion during loading response and late stance. This is because flexion of the knee joint in stance phase plays a shock-absorbing role and smoothes the COM trajectory during normal walking. SCOs therefore also need to provide a near-normal walking pattern for subjects with less lower limb muscle strength than healthy subjects. Using a pow-ered SCO may provide this, but the slow walking speed provided by these orthoses needs to be improved,16,17 and therefore, more research is needed in this field to provide more advanced powered SCO designs.

Using SCOs has been shown to provide improvement in frontal plane pelvic motions. Pelvic obliquity and verti-cal and lateral displacement have all improved with less abnormal gait deviations being noted (such as circumduc-tion, hip hiking, and vaulting gait) during walking, but the number of participants in these studies has been low. Improvements in hip and pelvic motions were small and did not occur consistently among all studies, making it dif-ficult to generalize this point of using SCOs compared to a locked KAFO. Future longitudinal studies involving more subjects and with longer training times with this type of orthosis may demonstrate whether the SCOs improve hip and pelvic kinematics.

The mean speed of walking when using SCOs has dem-onstrated lower walking speeds compared to a locked KAFO. Gait training with SCOs is also needed to produce a successful outcome in improving temporal spatial and kinematics during walking in KAFO users. Using a SCO needs a small knee extension moment to disengage knee joint locking in late stance. Experience of users during walking with the SCOs must be increased over time to pro-vide more ability in controlling the orthosis. The concen-tration required for SCKAFO control may be the cause of the shorter stride lengths demonstrated, associated with longer stride times, and therefore slower walking speeds

compared to walking with a locked KAFO. Another reason why SCO use does not improve walking speed is that stud-ies have compared experienced KAFOs users with sub-jects who only had a short time to acclimatize to walking with the SCOs. Consequently, gait training with SCOs should be performed for several days or weeks to become experienced in walking to increase ability and confidence of users to control the SCOs and improve gait function before being compared to other devices.

Production of SCKAFOs started in the early 1970s, and since then there have been continuous improvements and modifications in their design, including the use of hydrau-lic24 friction,26 elastic27 or impingement28,29 clutches,30,31 and brake mechanisms23 to provide the stance control con-cept. In commercially available SCKAFOs such as the E-Knee from Becker Orthopedics, the Horton stance con-trol knee joint, and the Sensor Walk from Otto Bock, weight-activated control is used. In the E-MAG Active from Otto Bock and SPL, the control of knee joint is posi-tion sensor activated. The Free Walk, UTX, and Full Stride/Safety Stride are ankle activated. According to cost, size, weight, or poor functionality, some of these designs have not led to clinical and commercial production, and develop-ment was based on mechanical and electromechanical mechanisms. New technologies can, however, be used to improve function of SCKAFOs; for instance, the use of actuators and sensors in lower limb orthoses have intro-duced new capabilities for adaptive control in SCOs.22,32,33

The selected studies are not analyzed according to the PEDro scale. This point was the main limitation of this study. The studies’ flaws included lack of randomization procedures, lack of control group, no masking of examin-ers and patients, and also there was lack of similarity among groups. These more recent studies have not sub-stantially improved the quality of the research. There is a continuing need for high-quality experimental studies in this area.

Future studies should therefore include the following:

•• A study includes meta-analyses to produce improved and more reliable conclusions according to speed, cadence, pelvic obliquity, and step length;

•• A comparison between the different types of SCKAFOs;

•• A comparison of SCOs and locked KAFOs in their effect on energy consumption and endurance of walking in KAFO users to add more clarification on the effect of this type of orthosis in the rehabilita-tion of walking;

•• The design and construction of more advanced SCOs to further improve structural characteristics of orthosis in KAFO users is recommended;

•• The design and construction of more advanced powered SCOs as future designs of orthosis for use in rehabilitation of walking in KAFO users;

12 Prosthetics and Orthotics International

•• An investigation into the effect of gait training with SCOs on walking parameters in future designs of studies;

•• An investigation into the effect of SCOs on COM displacement and stability in quiet standing;

•• Although cosmesis was not evaluated in using SCOs on KAFO users, consideration should be given to improve cosmesis of walking when KAFO users wear this type of orthoses;

•• The effect of SCOs on quality-of-life measures and social participation compared to KAFOs.

Conclusion

SCKAFOs have been shown to support the knee joint dur-ing stance phase and provide free knee movement during swing phase successfully in all the walking studies ana-lyzed.15 SCKAFO designs have provided improved gait kinematics for KAFO users. Using SCOs has been shown to provide improvement in pelvic obliquity and vertical and lateral displacement during walking. Despite the advantages of wearing a SCO, this type of orthosis has not demonstrated a significant improvement in producing decreased energy consumption.8,13 Lower walking speeds have been reported when using SCOs compared to a locked KAFO. Development of new design of SCO that provides more normal patterns of walking is required in this field. To improve walking, additional gait training and accommodation periods are needed before walking with SCOs by KAFO users.

Author contribution

All authors contributed equally in the preparation of this manuscript.

Declaration of conflicting interests

The authors did not have any conflicts of interest with regard to the study presented in this article.

Funding

We thank the Iran National Science Foundation for financial sup-port (grant number 92001422) for this research.

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