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Adolescent Idiopathic Scoliosis: Cobb Angle Relative to Overall Balance
By Andrew J. Mills, CO (UK) 1. The definition of a successful orthotic management outcome is
generally a stabilization or improvement of the pre-treatment Cobb
angle for a patient who had been considered to be at significant
risk of progression.
The Scoliosis Research Society (SRS) define stabilization as +/-
5 degrees and an improvement as - 6 degrees or more from the
pre-treatment Cobb angle.
These definitions of successful outcomes are well accepted and
used in orthopedics around the world.
It is important to define patients suitable for conservative
treatment:
- To prevent over-treatment of potentially minimally or
non-progressive curves.
- To prevent futile treatment of curves where surgery is
inevitable.
In 2005, the SRS published strict criteria for future brace
studies 1 .
The purpose of this paper is to allow meaningful comparison of
studies carried out with different conservative treatments and to
prevent inclusion of inappropriate patients giving false
results.
The SRS brace study guidelines restrict inclusion criteria to
only patients with high risk of progression, and define a minimum
two-year post-brace treatment follow-up as an acceptable outcome
measurement point.
Additionally all recruited patients, including those who are
noncompliant, must be counted in the overall percentage outcomes
for success or failure. This condition might seem harsh in that it
considers as failure any noncompliant patient regardless of outcome
as well as patients lost to follow-up, but it does ensure that
compliance with the treatment is part of the outcome. Previously,
brace studies have been flawed in that they have measured outcomes
either at the end of treatment or with very short follow-up. In
some studies, outcomes have even been judged in-treatment, which
has no validity whatsoever.
Defining In-Treatment Goals
Definition of in-treatment goals that may ultimately lead to
optimal outcomes (two years post brace weaning) must be brace and
even curve specific. Oversimplification of this task and the
imposition of general rules cannot give optimal outcomes for
patients.
Initial in-treatment goals by which we may judge potential brace
efficiency are not easy to define. The traditional goal of a
50-percent minimum reduction of the pre-treatment Cobb angle and
that a larger reduction would be better is now being challenged.
Clearly many other factors are involved in producing stabile
results post-bracing of which postural balance is only one.
 SpineCor Dynamic Corrective Bracing seeks to
address the neuromuscular as well as the skeletal factors involved
in the progression of an idiopathic scoliosis 2,8,9 .
The in-treatment objectives of Dynamic Corrective Bracing are very
different to those for rigid bracing; a slow progressive reduction
in Cobb angle is expected (not necessarily on the day of brace
fitting as with rigid braces). Maximum in-brace Cobb angle
reductions are normally achieved within six months and may be
anywhere between 10-100 percent (not a standard 50 percent as
required for rigid bracing). The important difference between
SpineCor Dynamic Corrective Bracing and other bracing systems is
that the curve reductions achieved in treatment are maintained
post-treatment even at five-year follow-up 3 .
Essentially the Cobb angles archived in treatment are those the
patient will end up with at the end of treatment. Comparisons,
therefore, of effectiveness in treatment between SpineCor and other
braces are not easy to make.
Acceptability of the initial dynamic corrective brace fitting
Cobb angle reduction is dependent on curve flexibility and
therefore potential reducibility.
The SpineCor Dynamic Corrective Brace treatment protocol advises
a specific radiological method of determining curve flexibility and
reducibility.
The ultimate treatment goal should be to avoid surgery; beyond
this, the measurement of outcomes for all treatments should take
into account Cobb angle reduction, postural balance, and
cosmesis.
2. The relationship of curve balance to Cobb angle reduction is
indeed important since both may impact adult progression and the
indication for surgery. There is absolutely no doubt in my mind
that we should strive to avoid surgery.
Long-term studies now question whether the long-term interests
of some patients are better served by surgical fusion or by doing
nothing.
 The question as to whether it is more important to
achieve balance or maximum curve reduction during brace treatment
is not simple to answer. Generally there should be a balance
between the two, and they are not necessarily in conflict with one
another, but in certain cases postural balance may be more
important than maximum Cobb angle reduction. It is not really
possible within the context of this text to detail each and every
case where the Cobb angle reduction may be compromised or a
compensatory curve created or increased to achieve a better, more
stabile postural balance. There are cases where this makes sense
within the context of SpineCor Dynamic Corrective Bracing and can
be equally true in the context of rigid bracing.
3. In the case of single major right thoracic curves apex T7-T10
with no lumbar compensation and which by definition exhibit a large
right lateral shift of the thorax in relation to the pelvis,
allowing some lumbar compensation can be beneficial. Such
alteration in postural balance could reduce the abnormal mechanical
loading of the vertebral growth plates thought to be largely
responsible for progression of scoliotic curves.
Research 4 by Ian A.F. Stokes, PhD (The Centre for
Spinal Studies and Surgery, Queens Medical Centre, Nottingham, NG7
2UH, UK), has produced a hypothesis relating to the etiology of
adolescent idiopathic scoliosis (AIS) that has significant
implications for future brace design and treatment protocols.
While there is no consensus, there is strong evidence to suggest
that the initiating factor in AIS is genetic, and several
hypotheses have been published on this subject, notably by Caroline
Goldberg, MD, 5 and Christine Coillard, MD 6
.
Stokes' hypothesis assumes the pre-existing (genetically created
10 ) scoliosis curve initiates mechanically modulated
alteration of vertebral body growth that in turn causes worsening
of the scoliosis. Stokes used mathematical simulations to test
whether the calculated loading asymmetry created by muscles in the
scoliotic spine could explain the observed rate of scoliosis
increase due to vertebral growth modulation and altered
compression. While still the subject of debate, if true, Stokes'
mechanical modulation hypothesis does challenge the pathogenesis of
progressive AIS generally attributed to the Hueter-Volkmann
7 or Delpech effect on which conventional brace
treatment is based.
The research of Stokes, Goldberg, and Coillard all points to the
need for bracing to have a dynamic effect on the growth plates and
to in some way reverse the abnormality of the neuromuscular system
created by the scoliosis and its progression.
In my past experience, creating compensatory curves in rigid
braces eventually leads to a structural deformity. While this
compromise might still be better than leaving the patient with very
unstable postural balance, this can be avoided using the SpineCor
Dynamic Corrective Brace. My experience to date has been the same
as the SpineCor research center at Sainte-Justine Hospital,
Montreal, Quebec, Canada, in that small compensatory curves created
in treatment do not persist as structural curves
post-treatment.
4. Research into postural balance versus Cobb angle reduction
might well be interesting, but I do not believe this is the
direction fundamental research on scoliosis etiology is suggesting
bracing should go.
I might suggest readers' look at what The International
Federation Body on Scoliosis Etiology (IBSE) and its recently
introduced Electronic Focus Group (EFG) are doing. The conclusion
of Stokes' article (Biomechanical spinal growth modulation and
progressive adolescent scoliosisa test of the vicious cycle'
pathogenic hypothesis) Scoliosis: 2006, 1:16 reads as
follows:
"The simulations indicate that a substantial component of
scoliosis progression during adolescent growth is biomechanically
mediated. It is possible that sustained muscle rehabilitation
programs could alter the prevailing spinal loading, since the
muscle force analyses [88] indicate that different neuromuscular
activation strategies are possible, with differing likelihood of
loading the asymmetrically. To avoid the unnecessary treatment of
non-progressive curves, a means of identifying progressive curves
at an early stage is needed."
 The SpineCor Dynamic Corrective Brace is such a
postural re-education device capable of sustainable (20 hours per
day) muscle rehabilitation to alter spinal loading.
Development of the SpineCor Dynamic Corrective Brace came out of
the fundamental research into the etiopathogenesis of AIS at
Sainte-Justine Hospital in the mid-'90s. Over 12 years of clinical
studies have shown this approach to be effective providing
treatment is initiated before the skeletal deformity is too
advanced. Clearly early treatment is important, but at the same
time this carries the risk of some unnecessary treatments of
non-progressive curves. C.H. Rivard, MD, and Christine Coillard,
MD, of Sainte-Justine Hospital have developed methods of evaluating
patients at high risk of progression, but these do rely on great
experience and high level of skill. Currently another research
group at Sainte-Justine is clinically trialing a new test, which
promises to clearly identify those patients at certain risk of
progression, thus allowing early treatment without risk of
unnecessary treatment. Early treatment of idiopathic scoliosis,
especially with SpineCor, should give the best possible outcome for
the individual patient. This has certainly has been the case in my
own clinical experience with SpineCor over the past seven
years.
5. Clearly patients could benefit and are crying out for better
brace designs. Orthotists are looking for better braces that are
more effective and research-based, consider all the progression
factors of AIS, are clinically proven, have no side effects, are
comfortable and unobtrusive to wear, and allow better compliance.
While some misconceptions still exist about SpineCor treatment, it
does work, patients prefer it, and it is available in the United
States.
For further information on the SpineCor Dynamic Corrective
Brace, contact Becker Orthopedic, 635 Executive Drive, Troy, MI
48083; 800.521.2192;www.beckerorthopedic.net
Andrew J. Mills, CO (UK), is managing director of the
SpineCorporation Limited, UK (www.spinecorporation.com)
Editor's note: This article is for reader information
only. The O&P EDGE does not endorse any particular
product or service.
References
- Richards, B. S., R. M. Bernstein, C. R. D'Amato, and G. H.
Thompson, 2005, Standardization of criteria for adolescent
idiopathic scoliosis brace studies: SRS Committee on Bracing and
Nonoperative Management: Spine, v. 30, no. 18, p.
2068-2075. Ref. Type: Journal. Ref ID: 78
- Coillard, C., M. A. Leroux, J. Badeaux, and C. H. Rivard, 2002,
SPINECOR: a new therapeutic approach for idiopathic scoliosis:
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- Coillard, C., M. A. Leroux, K. F. Zabjek, and C. H. Rivard,
2003, SpineCor--a non-rigid brace for the treatment of idiopathic
scoliosis: post-treatment results: Eur.Spine J, v. 12, no.
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- Stokes, I, A, F, Burwell, R, G and Dangerfield, P, H.
Biomechanical spinal growth modulation and progressive adolescent
scoliosis-a test of the vicious cycle' pathogenic hypothesis:
Summary of an electronic focus group debate of the IBSE.
Scoliosis 2006, 1:16 doi: 10.1186/1748-7161-1-16
- Goldberg, C, J, Fogarty, E, E, Moore, D, P, and Dowling, F, E.
1997 Scoliosis and Developmental Theory, Adolescent Idiopathic
Scoliosis. SPINE Volume 22, Number 19, pp 2228-2236
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- Castro, F. P., Jr., 2003, Adolescent idiopathic scoliosis,
bracing, and the Hueter-Volkmann principle: Spine J, v. 3,
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- Coillard, C., and C. H. Rivard, 1996, Vertebral deformities and
scoliosis: Eur.Spine J, v. 5, no. 2, p. 91-100. Ref. Type:
Journal. Ref ID: 23
- Coillard, C., M. A. Leroux, K. F. Zabjek, and C. H. Rivard,
1999, [Reductibility of idiopathic scoliosis during orthopedic
treatment]: Ann.Chir, v. 53, no. 8, p. 781-791. Ref. Type:
Journal. Ref ID: 21
- Bashiardes, S. et al., 2004, SNTG1, the gene encoding
gamma1-syntrophin: a candidate gene for idiopathic scoliosis:
Hum.Genet., v. 115, no. 1, p. 81-89. Ref. Type: Journal.
Ref ID: 6
Table Of Contents - May 2007
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