Brace Yourself: Redesigning the Charleston Back Brace

Brace Yourself: Redesigning the Charleston Back Brace
Ingrid Marko
Massachusetts Academy of Math and Science
Abstract
A problem with the Charleston bending back brace is that it may be designed
incorrectly and therefore must be remade. This wastes time and effort and delays
the patient’s treatment for scoliosis. The goal of this project was to design an
adjustable brace that can function like the Charleston bending brace. This design
should be capable of immediate alteration without the need for reconstruction.
The Charleston and Boston braces, and the dynamic hip stabilizer inspired
the design of the researcher’s device. The first prototype was manufactured by
fitting copolymer plastic and Aliplast foam around a plaster mold that was made
using the casting method on a patient. The second prototype featured a proximal
band made from carbon-glass polypropylene composite along with the original
pelvic stabilizer. The results for both prototypes proved that the brace could be
adjusted so that it bends the person’s spine against the curve to a near 0° Cobb
angle. It was durable, efficient, and provided accurate results. The brace will insure
that the patient receives quality treatment quickly.
Introduction
A growing problem with the increase of people that develop scoliosis has led
to a renewed interest in studies of back brace design. Scoliosis is a musculoskeletal
disorder that affects 4 in every 1000 people in the United States. It affects primarily
females with an occurrence of 7:1 (girls: boys). This disease is rarely life threatening
and it is treatable; however, it is unfavorable among the public. Treatment includes
bracing or surgery, neither of which completely cures the person of this disorder. It
can still be passed down through generations as a gene that negatively alters a life
style. If left to its natural history, the spinal curve may progress to a point where
surgery is required for the patient. The treatment of bracing may have a negative
mental affect on a young patient, however it will help them in the future. The
importance of the Charleston braces, casting method, and any possible factors to
improve it will be discussed.
Literature Review
Spine Anatomy
The skeletal system is one of the most important parts of the human body. It
provides support, protection, and movement. The spine is found within this system
and is divided into two parts: the vertebrae and the spinal cord. The vertebrae are
irregularly shaped bones that are strong but can become weak because of bad
formation. The human spine comprises five parts: the cervical, thoracic, and lumbar
vertebrae and the sacrum and the coccyx. The primary function of the spine is to

support and protect the spinal cord. Each of the vertebrae include a neural arch
made from two pedicles and two arched laminae, that make up the body; a vertebral
foramen, that allows the spinal cord to pass through; spinous process, superior and
inferior articular processes, and an intervertebral foramen for the transit of spinal
nerves (Van De Graff, Kent, & Ward, 2002).
The main vertebrae of the spine are the thoracic and the lumbar, and the
curves in scoliosis are usually found in these regions. The thoracic vertebra connects
to the rib cage while the lumbar vertebrae connects to the surrounding muscle.
Intravertable disks connected through interlocked processes and ligaments support
each of the vertebrae. There is finite movement between the vertebrae alone, but a
wide range of movement from the spinal column itself (Van de Graff et al., 2002).
Figure 1. Lateral side of the spinal column. This side view depicts
the five parts of the spine showing the cervical, thoracic, lumbar,
sacral, and coccyx sections. This spine does not show the scoliosis
disorder (Bridwell, n.d.).

Figure 2. Vertebrae of the spinal column. This image shows all of
the vertebrae in the spine. The T’s referrer to the thoracic region
and the L’s to the lumbar (Galliani, n.d.)
In scoliosis, the vertebrae shift or do not form in the correct area, thus
leading to a defected spinal shape. In some cases, the curve can be large and prevent
important body functions. But, in most cases the curve can be fixed through certain
types of treatment.
Morphology of Adolescent Idiopathic Scoliosis (AIS)
Scoliosis is a condition in which a patient has a deformed spine. It occurs
frequently in growing children, but primarily in girls. Sometimes, a curve may be
small during childhood but can progress through time into adulthood. Treatment
becomes more difficult at this time. The curves in the spine can occur at any part of
the vertebrae, from the thoracic to the lumbar regions and there can be rotation in
the individual as well. There are several contributing factors that can account for
why this occurs, but there is not any known cause.
Scoliosis can form in children due to intervertebral motion coupling, spinal
buckling, and/or an imbalance in the muscles/bone growth (Stokes& Aubin, 2006).
Generally, a lack of nutrition in growing children can lead to scoliosis because the
rate of their skeletal growth is affected along with the strength of their bones.
Treatment for scoliosis includes bracing or surgery. There are different types
of braces used presently and each performs in a slightly different way. Sometimes,
doctors decide not to treat the patient if the curve is small and does not seem to be a
health risk. In other cases, patients may be taken directly into surgery.
Current Treatment for Patients with AIS
Knowledge of determining whether patients need surgery is essential in
figuring out what type of treatment is necessary for them. An orthopedic doctor has
the choice of providing a patient with treatment. They may recommend surgery if
the curve is large or some form of bracing. The common braces used are the Boston
brace, which uses pressure pads to correct the curve; and the Charleston bending

ace, which is used to bend against the curve. The Milwaukee brace is rarely used
anymore because the previous two braces are more modern and efficient. The main
difference between them is that the Boston brace is worn for 23 hours a day, while
the Charleston type is worn only during the night for about 8 hours. Some doctors
do not believe in the effectiveness of the Charleston brace because it is worn for
small lengths of time, but studies have proven that it is just as effective as the
former. Unlike the Boston brace, however, it does not take the rotation of the
vertebrae into consideration (personal communication).
Figure 3. Charleston bending back brace. The figure shows a person
wearing the brace in a sleeping position. The brace is bending their torso
against the curve of their scoliosis. It is typically worn for about 8 hours a
night (“Types of braces”, 2007).
Before having a brace made, the doctor will give the patient an x-ray to
measure his curve. The Cobb angles indicate the measurement and they are used to
find two curves in the spine, usually in the thoracic and lumbar regions. In each
measurement, the maximal inclination to the other maximal inclination, found at the
end plates of the vertebrae, is used to calculate the angle (Stokes & Aubin, 2006).
After the initial x-rays are taken, they will be sent to an orthotist who will
make the brace. Recently orthotic and prosthetic experts have expressed an interest
in developing new ways to design and manufacture back braces with quicker and
better results. However, the original casting method is mainly used. After the brace
is made, the doctor will tell the patient how it should be used and for how long it
should be worn. It is the patient’s responsibility to follow the orders. If worn
properly, the brace will be successful.
The Casting Method
The casting method is a procedure in which an orthotist makes the brace
using a casting of the patient’s torso. First an initial clinical exam should take place

in which the orthotist can take note of the patient’s flexibility and guide him on
planning out the appearance of the brace before the procedure is conducted.
Some flexibility tests include having a patient bend over and reaching his
toes, and standing up straight then bending laterally. Resistive force may be
necessary to see the stiffness of his spine.
Afterwards, a standing x-ray should be taken for the brace planning. The x-
ray becomes the blue print used in planning out the Charleston brace design for a
patient. Several angles are measured and the placements of the corrective forces are
determined. When making the blue print the orthotist should consider the sacrum
visible mark for the center line, the vertebral tilt angle which determines the limits
of each scoliotic curve, the pelvic tilt angle, the lumbar/pelvic relationship angle,
and the Cobb angle which is extremely important in locating the superior and
inferior bodies in the curvature (Ralph Hooper, Reed, & Price, 2003).
The x-ray of the spine should be studied carefully to determine where the
forces would be applied for unbending. The first main force is the lateral shift force.
This force should move the spine beyond the centerline and maintain that position
during unbending (Ralph Hooper et al., 2003). It must never be compromised or
ignored. The stabilizing force is applied near the bottom of the lumbar curve and the
pelvic area. The unbending force is the main curve reducing force in which pressure
is applied opposite the lateral shift force.
Figure 4. Applied forces for unbending. The figure shows a crooked spine with
the three main forces labeled. It accurately depicts how the placement of the
forces and how they work together to unbend a patients spine (Ralph Hooper
et al., 2003).
The classifications of the scoliotic curves are very important to an orthotist.
These are used in correction techniques and they help define curves and act as
reminders on how to treat specific ones. The Kings classification describes five types
of curves. Type one is S-shaped and both the thoracic and lumbar curves cross the
midline and the lumbar curve is longer than the thoracic one (Ralph Hooper et al.,
2003).

Figure 5. King type one curve. This curve is a type one and it depicts the
applications and location of the forces (Ralph Hooper et al., 2003).
King type two curves are very similar to the type one curves. They are both S-
shaped and both the thoracic and lumbar curves cross the midline. Here, however,
the thoracic curve is greater than the lumbar one (Ralph Hooper et al., 2003).
Figure 6. King type two curve. This shows the curve with the applied
forces correctly labeled. If unbending is successful, the curve should
appear nearly straight (Ralph Hooper et al., 2003).
Type three curves are the easiest to correct and they have an overhang
appearance. They are mainly thoracic curves and the lumbar segment does not cross
the midline in this case.

Figure 6. King type three curve. The curve is relatively simple to
correct. The applied forces are labeled and the curve lies in the
thoracic region (Ralph Hooper et al., 2003).
The type four curves are long and located in the thoracic region. The
vertebrae can be centered over the sacrum. Here the spine should be shifted to the
midline before being unbent (Ralph Hooper et al., 2003).
Figure 7. King type four curve. The curve in the thoracolumbar area is
bent over the sacrum and can align with the edge of the pelvis. Shifting
this curve to the midline is important (Ralph Hooper et al. 2003).
Type five curves are very similar to the type four curves in the way they are
treated. These types of curves are double thoracic instead of single. They are also
rarely treated with the Charleston bending back brace (Ralph Hooper et al., 2003).

Figure 8. King type five curve. There is a double thoracic curve that
passes over the sacrum. This is treated the same way as the type 4
(Ralph Hooper et al. 2003).
Once the patients x-ray has been closely examined and classified as one of
the King types, the patient will be called in for another appointment. The mold of
their torso will be made with stockinettes. Measurements of the patient will also be
taken and markings will be placed on the cast, which will be filled with plaster
afterwards. The plaster will be taken to the workshop and fixed (if needed) before
having the plastic heated and placed on it. Once the brace is completed, the patient
will come in for a fitting before taking the brace with them (Ralph Hooper et al.,
2003). An x-ray of the patient with the brace on is taken of them in the supine
position to make sure it functions correctly. If the brace is incorrect, a new one has
to be made. About 1 out of 20 braces have to be remade due to error and incorrect
function (personal communication). The main source of error is due to the use of
educated guessing of when and where the forces are applied and how much
pressure is used (personal communication).
X-Rays
Philips Digital Diagnost, V 2.0, is an x-ray machine used in medical offices. It
has a moveable vertical stand, height adjustable table that includes a ceiling
suspension system and uses a wireless portable detector. It can cover vertical,
horizontal, and cross lateral positions of a patient. The x-ray dose that is emitted
from the machine to digitally capture the image is low and does not greatly
endanger the patient’s health (“Digital diagnost”, n.d.).
The camera captures the image and wirelessly transports it through a
network system. The image can be accessed through IDX Imagecast, an online
program that allows the medical practitioners, or orthopedic doctors, to observe the
x-ray and calculate Cobb angles.

Figure 9. Philips digital diagnost, v 2.0. This is the x-ray
currently being used in medical facilities. It reduces x-
ray emission and is moveable to take a variety of images
(“Digital diagnost”, n.d.).
Patents
The Dynamic Hip Stabilizer is a device used to reduce any hip
dislocations after a surgery or prevent rotation and translation. The device consists
of a pelvic girdle, one thigh cuff, and one or more straps that connect to the girdle.
The design of the pelvic girdle goes around the patient’s hips and prevents and
controlls any movements (U.S. Patent No. 20040116260A1, 2009).
Figure 10. Dynamic hip stabilizer. The top portion of this device
is the pelvic girdle which was used as a model for the
experiment. It controls or prevents any unwanted hip
movements (U.S. Patent No. 20040116260A1, 2009).
The Charleston bending back brace was produced in 1989 and is worn while
the patient is asleep. It is designed for patients with scoliosis and it works by
bending their backs against the curve. The brace provides a lateral shift force,
unbending force, and a stabilizing force (U.S. Patent No. 2007/0010768A1, 2010).

Figure 11. Charleston bending brace. This is used to treat AIS n
patients and works by bending their spine against the curve. It is
worn in the nighttime (Cowan, 2008).
The Boston brace is worn for 23 hours a day and it is not curved, but straight
and rigid. It uses pressure pads that push the spine into a straighter position. The
brace also exerts a force on the ribs and back and gives the patient a near perfect
upright posture. The only problem with using the brace is that it can lead to a loss of
flexibility in the patient’s spine due to the brace’s rigidness and the inability to move
while wearing it (U.S. Patent No. 2007/0010768A1, 2010).
Figure 12. Boston brace. This is the day brace worn by patients with
scoliosis. It is rigid and straight and it corrects the spine by using pressure
pads (“Types of braces for scoliosis”, 2007).
Material Science
Copolymer plastic sheets are a mix of polypropylene and low-density
polyethylene. When they are heated they become self-adhesive and have the ability
to be shaped when used with a vacuum. The sheets are usually heated between 163°
C to 191 ° C and the Copolymer is less brittle than polypropylene alone, however the
plastic can experience blanching, shrinking, or bubbling during high stress and
temperatures (“Polypropylene-co-polymer plastic sheets”, n.d.).
Polypropylene is a resin composed of the polymerization of propylene. These
plastics are tough, flexible, lightweight, and heat resistant. The propylene compound
is obtained by the thermal cracking of ethane, propane, butane, and the naphtha
fraction of petroleum. The chemical structure of this is CH2=CHCH3 and consists of
carbon atoms bonded to hydrogen atoms. The polypropylene is stiffer, stronger,
harder, and softens at much higher temperatures than polyethylene
(“Polypropylene”, 2012).
Polyethylene is a synthetic resin made from the polymerization of Ethylene.
The gaseous hydrocarbon is made from cracking ethane that can be retrieved from

natural gas or distilled petroleum. The chemical compound appears in the form of
C2H4, which is composed of two methylene units linked to carbon atoms by a double
bond. When the structure repeats itself many times, it becomes Polyethylene. The
low-density version of the plastic occurs when the structure becomes branched due
to high temperatures. The branches prevent the molecules form packing close
together, thus resulting in a soft and versatile material (“Polyethylene”, 2012).
Polyethylene is also used to make foams such as Aliplast, which are water,
bacteria, and odor resistant. Cellular foam is composed of plastic in gas bubbles,
which are thermoplastic and opened-celled. They can undergo a great deal of
compression and pressure (Kuncir, Wirta, & Golbranson, 1990).
Carbon-glass polypropylene composite is a combination of carbon fiber cloth
and two layers of polypropylene plastic. The carbon fiber cloth is placed in between
the polypropylene layers and after it is heated it becomes very rigid. The product, in
use, may cause skin and eye irritation if exposed to them.
Engineering Plan
Engineering problem being addressed:
A problem with the Charleston bending back brace is that it may be designed
incorrectly and therefore must be remade. This wastes time and effort and delays
the patient’s treatment for scoliosis.
Engineering Goals:
The goal of this project was to design an adjustable brace that can function like the
Charleston bending brace. This design should be capable of immediate alteration
without the need for reconstruction.
Description in detail of methods or procedures:
The engineering design process will be followed in order to make a
successful device. The design criteria for the project include: a working model that
can be fit on the researcher with scoliosis that can bend her as necessary, little to no
interference of the x-ray image, and reusability. An x-ray will be taken to test the
device on the author. If the torso can be bent in any way, while only pushing on the
desired pressure points, it will be considered a successful model. Power tools such
as a pneumatic cast saw, industrial sander, and plastic-cooking oven will be used.
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Acknowledgements
The author wishes to thank several mentors who assisted in various aspects of this
project. Ms. Julia Wildfong provided ongoing guidance and support in experiment
design and execution. Karen Lynch provided a great aid in the design of the device
and assisted in the making of the project. Dr. Errol Mortimer helped provide
knowledge regarding scoliosis, recommended Ms. Lynch as a mentor, and most
importantly aided the author in testing the device by allowing her to use x-rays.
Jamison Haugen and John Gannon also provided a great deal of help in the
construction of the device. Mr. William Ellis aided the author with the force testing
and data collection. Dr. Judith Sumner aided the author with editing her engineering
paper. Her parents also contributed by providing transportation and moral support.