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TriaCII Scoliosis Orthosis Promotes Proactive Treatment
By Miki Fairley
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James |
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The TriaCII orthosis for treatment of adolescent
idiopathic scoliosis (AIS) from Boston Brace International, Avon,
Massachusetts, is a dynamic tension-based orthosis in which the
forces acting on the spine are able to move with the patient,
rather than being static, as with conventional bracing, explains
James "Jim" Wynne, CPO, Boston Brace director of Education and
Training. "The whole premise of tension-based dynamic bracing is
that you have a lower force that moves with the patient," Wynne
continues. "Thus those forces are in constant contact with the
patient, so we maximize the time over which the force acts. It is a
custom-fitted orthosis that consists of two parts: lumbar and
thoracic. The lumbar part does not restrict lumbar motion; it
maintains the motion segment. The thoracic part consists of tension
springs that are adjusted to patient tolerance. A unique coupling
mechanism allows the two parts to move with each other."
The TriaC was developed jointly by the University Hospital of
Groningen and the University of Twente in the Netherlands. An
article in Medical Engineering & Physics, April 2002,
with an abstract at PubMed ( www.pubmed.gov ), by A.G. Veldhuizen, J.
Cheung, G.J. Bulthuis, and G. Nijenbanning of the University
Hospital of Groningen describe the TriaC as follows: "A transverse
force system, consisting of an anterior progression force
counteracted by a posterior force and torque, acts on the vertebrae
of a scoliotic spine. The aim of the newly introduced TriaC brace
is to reverse this transverse force pattern by externally applied
and constantly present orthotic forces. In the frontal plane the
force system in the TriaC brace is in accordance with the force
system of the conventional braces. However, in the sagittal plane
the force system acts only in the thoracic region. As a result,
there is no pelvic tilt, and it provides flexibility without
affecting the correction forces during body motion. In the current
preliminary study it is demonstrated that the brace prevents
further progression of the Cobb angle and axial rotation in
idiopathic scoliosis. The new brace has the added advantage of
comfort for the wearer, and it offers a better cosmetic appearance,
as well as, potentially, a better compliance."
Stopping Progression, Achieving Stability
"The aim is not so much to maximally reduce the Cobb angle, but
rather to achieve a stable, well balanced spine into adulthood,"
Wynne says. "How we get to that point, and how much correction is
needed is somewhat variable."
Wynne continues, "What the TriaCII studies are showing is that a
minimum of 20-percent in brace reduction of the Cobb angle is
necessary for success." Although often patients, once they are no
longer being braced, often return to the curve degree they had
before orthotic treatment, without that treatment, the progression
of the curve might have gone much further. For instance, if a
35-degree curve is corrected to 20 degrees with bracing, and later
returns to around 35 degrees, without the orthotic treatment, the
curve might have progressed into the 45-50-degree range in which
surgery may be considered necessary. Thus the goal of avoiding
surgery has been achieved.
Studies are finding that in many cases, the correction obtained
with the TriaC is being maintained for four to six years after
patients are weaned from the brace, Wynne says. "With conventional
bracing, the general tendency has been for patients to go back to
where they were before bracing."
John Michael, MEd, CPO, FAAOP, in a "John Michael's Corner" article, comments on the
TriaC: "The TriaC is custom-fitted from a kit of prefabricated bars
and straps... [T]he TriaC is based on a series of three-point
pressure systems that correspond to those exerted by the
Boston/Milwaukee orthoses. This orthosis also seems easy to don and
doff and less constricting than most body jacket styles."
Indications for Use
Indications for using a TriaCII orthosis are, according to
Boston Brace:
- The patient has an idiopathic scoliosis with a Cobb angle of
between 15 and 35 degrees.
- The thoracic apex of the primary or secondary curve is between
TH7 and TH11.
- The patient is skeletally immature. According to international
guidelines this means Risser 0-2, pre-menarche or post-menarche
less than one year.
- The patient has a flexible spine.
- The patient's posture is "normal."
- The patient is motivated to wear the orthosis.
- As the patient is not an adult, the parent's consent to him/her
wearing the orthosis is needed.
Hypothesis on AIS Etiology
 The dynamic tension bracing action of the TriaC
aims to help direct the growth of the spine, rather than reacting
to the growth of the spine, as is the case of conventional bracing,
Wynne explains. The concept behind the TriaC is based on the
hypothesis that in progressive scoliosis, vertebral body wedging
during adolescent growth results from asymmetric muscular loading
in a "vicious cycle" (vicious cycle hypothesis of pathogenesis) by
affecting vertebral body growth plates (endplate physes).
An illuminating and interesting discussion on this theory can be
found online in an electronic focus group (EFG) conducted by the
International Federated Body on Scoliosis Etiology (IBSE) at www.scoliosisjournal.com/content/1/1/16
The text for the debate was written by Ian A.F. Stokes, PhD, who
has done research on the subject, and includes comments by various
experts as they weigh in on the debate.
 The site notes, "A frontal plane mathematical
simulation tested whether the calculated loading asymmetry created
by muscles in a scoliotic spine could explain the observed rate of
scoliosis increase by measuring the vertebral growth modulation by
altered compression. The model deals only with vertebral (not disc)
wedging. It assumes that a pre-existing scoliosis curve initiates
the mechanically modulated alteration of vertebral body growth that
in turn causes worsening of the scoliosis, while everything else is
anatomically and physiologically normal.' The results provide
quantitative data consistent with the vicious cycle' hypothesis.
Dr. Stokes' biomechanical research engenders controversy. A new
speculative concept is proposed of vertebral symphyseal dysplasia
with implications for Dr. Stokes' research and the etiology of
AIS.
"What is not controversial is the need to test this hypothesis
using additional factors in his current model and in
three-dimensional quantitative models that incorporate
intervertebral discs and simulate thoracic as well as lumbar
scoliosis. The growth modulation process in the vertebral body can
be viewed as one type of the biologic phenomenon of
mechanotransduction. In certain connective tissues this involves
the effects of mechanical strain on chondrocytic metabolism a
possible target for novel therapeutic intervention."
The TriaC has produced positive results for many patients, and,
according to Boston Brace, "With the open design, lightweight
construction, and the freedom of movement, patients will enjoy a
more comfortable quality of life throughout their treatment
process." 
Table Of Contents - May 2007
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