Thoracolumbar braces for the treatment of A.I.S.Is there any difference?

Thoracolumbar braces forThoracolumbar braces for
the treatment of A.I.S.the treatment of A.I.S.
Is there any difference?Is there any difference?
GEORGE SAPKASGEORGE SAPKAS
11stst
Orthopaedic DepartmentOrthopaedic Department
Medical School Athens UniversityMedical School Athens University
Athens GreeceAthens Greece

Adolescent
idiopathic scoliosis,
as defined by the
Scoliosis Research
Society, is
diagnosed when a
lateral spinal curve
of at least 11o
is
observed in a
patient who is
between ten years
old and skeletal
maturity

Natural historyNatural history
Without intervention, the curve is likely to progress
between the time of detection and the time of
skeletal maturity; the risk of progression increases as
the degree of curvature increases
Montgomery et al, Act. Orth. Scan, 1989

The risk of progression
increases with the
magnitude of the curve at
the time of detection
decreases with
increased age at the time
of detection
Younger girls
(ten, eleven, or twelve
years old) who had a
curve of at least 30o
at the time of detection
had the highest
likelihood of
progression, ranging
from 90% to 100%.
Nachemson et al, 1982

Current Options for
Treatment
Curves that are 20o
or less before the
time of skeletal
maturity are
considered mild and
generally are
re-evaluated
every six months.

Curves that
progress 5o
to 10o
and
those that are more
than 30o
at the time
of diagnosis
(considered
moderate)
usually are treated
with a brace, as
early and intensive
bracing is believed
to preclude the need
for an operation in
most instances.

Curves
of less than 30o
rarely
progress after maturity
but larger curves may
continue to increase
throughout the life of
the patient
Weinstein et al, JBJS(am), 1994

Scoliosis’
correction with
spinal
instrumentation is
the treatment of
choice
for curves of more
than 45o
in children
who are still
growing,
for curves of more
than 60o
in patients
who have reached
skeletal maturity,
and for curves that
have continued to
progress even
after treatment
with bracing

Thoraco-lumbo-sacralThoraco-lumbo-sacral
orthosis (TSLO)orthosis (TSLO)
is the most commonis the most common
non-operativenon-operative
treatment intreatment in
progressiveprogressive
adolescent idiopathicadolescent idiopathic
scoliosisscoliosis
Ogilvie et al, Spine, 1994

By aBy a judiciousjudicious
combination ofcombination of
pressures applied topressures applied to
the torsothe torso
over a prolongedover a prolonged
period, braceperiod, brace
treatment attempts totreatment attempts to
modify mechanicallymodify mechanically
the scoliotic spinethe scoliotic spine
morphologymorphology
and to controland to control
progression of spinalprogression of spinal
curvaturecurvature
Peterson et al, JBJS, 1995

The degree of spinalThe degree of spinal
correction is related tocorrection is related to
many interconnectedmany interconnected
parameters such asparameters such as
the correct abilitythe correct ability
(or flexibility) of the spinal(or flexibility) of the spinal
curvescurves
The shape and stiffnessThe shape and stiffness
of the brace shellof the brace shell
The location, size andThe location, size and
thickness of brace partsthickness of brace parts
The strap tensionThe strap tension
adjustmentadjustment
The biomechanicalThe biomechanical
properties of truncalproperties of truncal
tissues to transmit thetissues to transmit the
brace forces to the spinebrace forces to the spine
The duration of braceThe duration of brace
forces applied on theforces applied on the
torsotorso

The effectivenessThe effectiveness
of bracingof bracing
with a TLSO in thewith a TLSO in the
treatment oftreatment of
idiopathic scoliosisidiopathic scoliosis
has always been ahas always been a
highly disputedhighly disputed
topictopic

Conflicting opinionsConflicting opinions
in the literaturein the literature
stem fromstem from
inconsistencyinconsistency
In the patientIn the patient
populationpopulation
The evaluationThe evaluation
methodsmethods
Selection criteria forSelection criteria for
treatment amongtreatment among
different studiesdifferent studies

Ideally, bracesIdeally, braces
should beshould be
prescribed toprescribed to
patients withpatients with
with curves betweenwith curves between
3030oo
and 40and 40oo
, or with, or with
curves less than 30curves less than 30oo
who have a historywho have a history
of curve progressionof curve progression
with a high risk forwith a high risk for
continuedcontinued
progressionprogression
Edgar et al, JBJS, 1985
Kehl et al , Clin Orth, 1988
Lonstien et al. JBJS(Am), 1994
Nachemson et all, JBKS(Am), 1995

By bracing scolioticBy bracing scoliotic
curves that are notcurves that are not
likely to progress, thelikely to progress, the
brace may bebrace may be
erroneously deemederroneously deemed
effectiveeffective

Regardless of the betterRegardless of the better
understanding of theunderstanding of the
prognosticatorsprognosticators
for progressionfor progression
of scoliotic curves,of scoliotic curves,
brace treatmentbrace treatment
still failsstill fails
and clinician disagreeand clinician disagree
about its usefulnessabout its usefulness
Aubin et al, Spine, 1997
Carr et al, Spine 1989
Edelman et al, Act Orthop Belg, 1992
Winter et al, Spine, 1986

In adolescent girlsIn adolescent girls
with right thoracicwith right thoracic
curves between 25curves between 25oo
and 35and 35oo
the treatment withthe treatment with
a brace wasa brace was
successfulsuccessful
in preventingin preventing
progressionprogression
of more than 6of more than 6oo
Nachemson et all, JBJS, 1995

Using computedUsing computed
tomography,tomography,
demonstrateddemonstrated
significantsignificant
vertebralvertebral
derotation ofderotation of
scoliotic curvesscoliotic curves
treated withtreated with
bracesbraces
Aaro et al, Spine, 1981

When looking in long termWhen looking in long term
effectseffects
of bracing found that theof bracing found that the
Boston brace did notBoston brace did not
improve,improve,
but prevented, progression ofbut prevented, progression of
Vertebral rotationVertebral rotation
TranslationTranslation
Rib humpRib hump
Cobb angleCobb angle
The immediate improvementsThe immediate improvements
of Cobb angle and vertebralof Cobb angle and vertebral
rotation were lost at follow uprotation were lost at follow up
Wilers et al., Spine 1993

PressurePressure
distribution anddistribution and
forces generatedforces generated
by braces on theby braces on the
scoliotic deformitiesscoliotic deformities
were measured towere measured to
characterizecharacterize
bracingbracing
biomechanicalbiomechanical
action on the torsoaction on the torso
Chase et al., Spine, 1989
Cote et al, Scol. Deform., 1995
Jiang et al, Scol. Deform, 1992

Measuring meanMeasuring mean
brace forces exertedbrace forces exerted
locally by the bracelocally by the brace
found that correctionfound that correction
of curves was notof curves was not
solely depended onsolely depended on
the level of forcethe level of force
applied by the braceapplied by the brace
The patients with theThe patients with the
greatest curvesgreatest curves
achieved littleachieved little
correction despitecorrection despite
significant levels ofsignificant levels of
applied forceapplied force
Chase et al, Spine 1989

For the purpose of the studyFor the purpose of the study
A flexible tissue matrixA flexible tissue matrix
was developed,was developed,
composed of thincomposed of thin
circular sensors thatcircular sensors that
measure themeasure the
pressures generatedpressures generated
at the entire skin-at the entire skin-
brace interface.brace interface.
It was suggested thatIt was suggested that
Boston brace action isBoston brace action is
limited mainly tolimited mainly to
specific regions ofspecific regions of
pressurepressure
Cote et al, Scol. Deform., 1992 - 1995

Measurement ofMeasurement of
magnitude,magnitude,
locationlocation
and direction of pressuresand direction of pressures
generated by the bracegenerated by the brace
and the forces present in theand the forces present in the
straps fastening the bracestraps fastening the brace
while the pts assumedwhile the pts assumed
different positions,different positions,
found thatfound that
posterior thoracic padsposterior thoracic pads
provided scoliotic correctionprovided scoliotic correction
and derotation and thatand derotation and that
brace interface pressurebrace interface pressure
were present in all positionswere present in all positions

It was found that patientsIt was found that patients
withwith low strap forceslow strap forces hadhad
scoliotic curves thatscoliotic curves that
progressed while in theprogressed while in the
bracebrace,, whereas thosewhereas those
with high strap forces hadwith high strap forces had
a reduction in curvaturea reduction in curvature
It was concluded thatIt was concluded that
although high strap forcesalthough high strap forces
are necessary to ensureare necessary to ensure
lateral and derotationallateral and derotational
forces on the spineforces on the spine theythey
also cause undesirablealso cause undesirable
forces that induceforces that induce
lordosislordosis

Clearly theClearly the
biomechanical actionsbiomechanical actions
of the TLSO are still notof the TLSO are still not
well understoodwell understood
Considering that bracesConsidering that braces
are prescribedare prescribed
empirically, relying n theempirically, relying n the
experience andexperience and
observations of theobservations of the
orthopedist andorthopedist and
orthotist, it is possibleorthotist, it is possible
that treatment fails inthat treatment fails in
some patients becausesome patients because
of the inadequate forcesof the inadequate forces
exerted by the braceexerted by the brace

AnAn increase inincrease in
strap tension bystrap tension by
50% resulted in50% resulted in
an increase ofan increase of
20% in the20% in the
mean forcemean force
exerted throughexerted through
thethe
compressioncompression
padspads
Chase et al, Spine 1989

Strap forces influenceStrap forces influence
progression of scolioticprogression of scoliotic
curvescurves
Therefore it would seemTherefore it would seem
that the effectiveness of thethat the effectiveness of the
brace depends to a certainbrace depends to a certain
extend onextend on how tightly it ishow tightly it is
adjusted and fastenedadjusted and fastened
Currently, there is noCurrently, there is no
standardized strap tensionstandardized strap tension
at which the brace shouldat which the brace should
be fastened to obtainbe fastened to obtain
optimal resultsoptimal results

Some patients wereSome patients were
wearing their braceswearing their braces
less tight thanless tight than
others wereothers were
A great deal ofA great deal of
variability in thevariability in the
strap tension alsostrap tension also
was found thewas found the
patients were takingpatients were taking
different positionsdifferent positions
regardless of howregardless of how
tightly the strapstightly the straps
were originallywere originally
fastenedfastened
Aubi et al, Spine 1999

Even when theEven when the
patients returned inpatients returned in
the standing positionthe standing position
after havingafter having
performed other tasksperformed other tasks
these were alsothese were also
significant decreasessignificant decreases
in strap tensionin strap tension
Aubi et al, Spine 1999

Several authorsSeveral authors
believe that thebelieve that the
Heuter-VolkmannHeuter-Volkmann
principle contributesprinciple contributes
to the developmentto the development
of adolescentof adolescent
(A.I.S.)(A.I.S.)
Machida et al, Spione, 1999
Dickson et al, JBJS, 1984
Stokes et al, Spine, 1996

Briefly stated,Briefly stated,
asymmetricasymmetric
loading orloading or
compression ofcompression of
the growth platesthe growth plates
on the concaveon the concave
side of the curvesside of the curves
inhibit growthinhibit growth
leading toleading to
wedging of thewedging of the
vertebral bodiesvertebral bodies

Bracing a scolioticBracing a scoliotic
curve should, incurve should, in
theory, unload thetheory, unload the
growth plates on thegrowth plates on the
concave side of theconcave side of the
vertebral bodiesvertebral bodies
near the curve’snear the curve’s
apexapex

Growth stimulationGrowth stimulation
leading to structuralleading to structural
remodelingremodeling
of the vertebral bodies,of the vertebral bodies,
on the curve’s concaveon the curve’s concave
side may explain theside may explain the
improvementimprovement
or lack of curveor lack of curve
progression,progression,
as measured by Cobbas measured by Cobb
angles, reported withangles, reported with
successful bracesuccessful brace
management of A.I.S.management of A.I.S.
Lonstein et al, JBJS, 1994
Korovesis et al, Spine 2000

EvidenceEvidence
demonstratingdemonstrating
the biomechanicalthe biomechanical
effects of theeffects of the
Hueter-VolkmannHueter-Volkmann
on the vertebralon the vertebral
body growthbody growth inin
spinal deformitiesspinal deformities
is lackingis lacking

To our knowledge,To our knowledge,
no longitudinalno longitudinal
study of thestudy of the
principle andprinciple and
vertebral bodyvertebral body
growth rate ingrowth rate in
patients with A.I.S.patients with A.I.S.
has beenhas been
publishedpublished

The threshold andThe threshold and
limit of the forcelimit of the force
magnitudesmagnitudes
necessary for thenecessary for the
principle to applyprinciple to apply
in A.I.S. have notin A.I.S. have not
been delineatedbeen delineated

Because the spineBecause the spine
simultaneouslysimultaneously
experiencesexperiences
compressive andcompressive and
tensile forces,tensile forces,
it is unlikely that allit is unlikely that all
compressive forcescompressive forces
inhibit growthinhibit growth
and all tensile forcesand all tensile forces
stimulate growthstimulate growth

Adolescent idiopathic scoliosisAdolescent idiopathic scoliosis
bracing and thebracing and the
Hueter – VolkmannHueter – Volkmann
principleprinciple
Frank et al Spine Journal, 2003
The purpose of thisThe purpose of this
investigation was toinvestigation was to
determine whetherdetermine whether
long-term bracelong-term brace
treatment stimulatedtreatment stimulated
asymmetricasymmetric
chondrogenesis in thechondrogenesis in the
apical three vertebraeapical three vertebrae

Successful brace
treatment has been
positively correlated
with the total number
of brace-wear hours
per day
Successful brace
treatment may now
also be positively
correlated with the
ability of the brace to
initiate significant
positional changes
Rowe et al, JBJS, 1986
Howard et al, Spine 1998

Measurement error,
as well as the lack of
documented brace
wear, may represent
weaknesses of the
study.
Vertebral body
rotation is
notoriously
inaccurate on
unidimensional
radiographs.
A measuring error of
1 mm may
significantly change
a concave-to-convex
height ratio.

Similarly, the
radiographs on
which the results
were based
ignore the three
dimensional
deformity of
scoliotic curves.

In conclusion, the
retrospective
analysis of the data,
compared with the
prospective
analysis,
was more insightful
in determining the
importance of curve
flexibility as a
predictor of
successful brace
outcome.

Brace application
was a successful
treatment when
the initial
vertebral body
derotations were
maintained until
skeletal maturity

The efficacy of
brace treatment
in patients with
rigid curves was
questioned

A side-bending
radiograph to
assess curve
flexibility may be
cost effective in
preventing TLSO
application to
patients, with rigid
curves, unlikely to
benefit from its
use

Larger cohorts with
spiral computed
tomographs may
someday elucidate
whether the
Hueter-Volkmann
principle and
vertebral body
remodeling (if any)
occur in brace-
treated patients
with AIS.

A Meta-Analysis ofA Meta-Analysis of
the Efficacythe Efficacy
of Non-Operativeof Non-Operative
Treatments forTreatments for
Idiopathic ScoliosisIdiopathic Scoliosis
Dale et al, JBJS(Am), 1997

Graph showing the unadjusted mean proportions of success, with 95
per cent confidence intervals, for the twenty studies. LESS = lateral
electrical surface stimulation.

Although bracing
has long been the
mainstay of
conservative
treatment of
scoliosis,
its efficacy has not
been demonstrated
definitively in
prospective or
randomized clinical
studies in which it
has been compared
with other forms of
non-operative
treatment

The United States
Preventive Services
Task Force, in 1993,
stated: “There is
inadequate evidence
to determine
whether brace
therapy limits the
natural progression
of the disease
in a significant
proportion of cases”

In a 1994 study of the
long-term results of
scoliosis screening in
Dublin, noted: “Since
the incidence of
significant scoliosis
and of surgery is
independent of
changes in bracing
policy, the efficacy of
bracing in causing
significant change in
natural history must
be challenged.”
Goldberg et al, Orth. Trans. 1995-1996

In 1993, the
Prevalence and Natural
History Committee of
the Scoliosis Research
Society decided to
compare, with use of
meta-analysis, the
results of non-
operative treatment of
idiopathic scoliosis

The selected three important variables
for which sufficient information was
available across studies:
the type of treatment,
the level of maturity,
the criterion used to determine
progression of the curve (or failure of
treatment)

The type of
treatment was the
most straightforward
variable, as all of the
patients
had been managed
with bracing,
lateral electrical
surface stimulation,
observation

For the purpose of
analysis, the braces
were subdivided into
Milwaukee braces,
Charleston braces,
and all other types of
braces (primarily
thoracolumbosacral
orthoses),
and the bracing
regimens were
classified on the basis
of whether the brace
was worn for
eight,
sixteen,
or twenty-three hours
per day

On the basis of the
variables just cited,
the studies were
grouped into four
categories
according to the
predominant level
of maturity of the
patients

Juvenile (composed of
children who were nine
years old or less),
immature adolescent
(composed mostly of
children who were ten
to thirteen years old and
had a Risser sign of 2
or less),
mature adolescent
(composed mostly of
children who were more
than thirteen years old
and had a Risser sign of
3 or 4),
mixed (composed of a
mixture of immature
and mature adolescent
patients, with no clear
majority).

The criterion for
failure
ranged from 3 to 10 o
of progression; the five
studies in which no
criterion was specified
were classified as
unspecified in the
analysis. Progression
of the curve was
measured with use of
the Cobb method in all
studies
Bradford et al, Spine, 1983

The type of brace
had a significant
effect on the
outcome (QB = 58, p
< 0.0001; QW = 262,
p < 0.0001),
although this effect
was small compared
with the effects of
other variables

The daily duration for which
the brace was worn also had
a significant effect on the
outcome

The outcome was
significantly influenced
by the level of maturity
as well (QB = 160, p <
0.0001; QW = 161, p
< 0.0001).
The weighted mean
proportions of success
were 0.99, 0.88, 0.71,
and 0.60 for the
studies of mature
adolescent, mixed,
immature adolescent,
and juvenile groups,
respectively
Graph showing the weighted mean
proportions of success according to the level
of maturity. Curves generally were less likely to
progress as the level of maturity increased.

The criterion for
failure also
significantly affected
the outcome
Criterion for failure
was 6o
of
progression;
studies in which the
criterion was 5o
or
10o
had higher
proportions of
success

This additional
analysis also
demonstrated that
the type of brace
had a significant
effect on the
outcome
The weighted mean
proportions of
success were 0.99
for the Milwaukee
brace
Graph showing the weighted mean proportions of
success for the control condition and various bracing
regimens. Braces that were worn for twenty three
hours per day were significantly more effective than
all other treatments (p < 0.0001). TLSO =
thoracolumbosacral orthosis.

ConclusionsConclusions
The results of this
meta-analysis
support the
efficacy of bracing
compared with
lateral electrical
surface stimulation
and observation
only
Graph showing the weighted mean proportions of
success for the control group and for the groups
treated with lateral electrical surface stimulation
(LESS) and bracing

Bracing for twenty-
three hours per day
was associated with
the highest rates of
success

The age of the patient at
the start of treatment,
the criterion for failure,
and the bracing regimen
all had effects on
the statistical model

In practice, the
type of brace and
the daily duration
for which it is
worn cannot be
separated
completely

These data were not
adjusted to account for
compliance of the
patient with the
prescribed period of
brace wear.
We can only state that
when patients are told
to wear the brace
longer each day, they
have a better chance of
preventing progression
of the curve

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