Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION:
This invention relates to orthopedic devices having
broad medical applications. These devices are used to
support, position, protect, immobilize andyor restrain
portions of the body.
Orthopedic devices is a broad term that is used to
describe medical structures such as casts, splints, supports,
braces and other means utilized to support, immobilize,
restrain, protect and postion body portions. They are used
im many fields, including the physical medicine and rehab-
ilitation field, general medicine, neurological field, and
the veterinary field. They are also used to prevent recur-
rance of previous disabilities, and to prevent discomfiture
and subsequent disability.
Different types of the known orthopedic devices have
specific uses and it has been necessary to select a specific
type of orthopedic device to meet the requirements of a
specific intended usa~e. The treatment of fractures usually
requires total immobilization. Casts made of Plaster of
Paris (plaster) are commonly used for this purpose. Plaster
casts have the disadvantage that it takes hours to harden,
the cast is excessively heavy, it has poor compression
strength and is readily crushed or broken, and it has poor
resistance to water and poor x-ray penetrability. Splints
have been made of wood and metal and even plastic~ Those
synthetic base orthopedic devices which have been proposed
and/or introduced commercially by others have had
disadvantages inherent in some or all uses.
Orthopedic devices should desirably be lightweight.
They should be capable of immobilizing a portion of the
body when that is the intended purpose. Similarly, they
should be capable of resilient support and/or cushloning
when that is required. The orthopedic device should be
capable of being formed in a practical manner and without
disco~fort to the patient. Additionally, the orthopedic
device should not have properties which irritate the
patient during the period in which it is in service.
Orthopedic devices fulfilling these requirements are disclosed
in my copending application, S. N. 465,404, filed April
29, 1974.
It is an object of this invention to provide orthoped-
ic devices having wide applicability and a unique combination
of desirable properties.
SUBJECT MATTER OF THE I~VENTION:
me orthopedic device of the present invention is a
plastic sheet member having at least one side covered with
a thermally insulating layer~ The plastic sheet member is
at least about 40 mils thick. The insulating layer is at
least about 10 mils thick~ It is capable of being molded
(formed) with application of normal finger pressure when
the plastic is at a
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temperature above about 120F. When the device is heated to
substantially above its molding temperature, e.g., 165-350~F,
and allowed to cool in air and ultimately on the patient as
it is being formed, the temperature at the outside of the
insulating layer is at least about 25~F cooler than the
plastic member and preferably at least ~0F cooler.
The orthopedic device has both sides of the plastic
sheet member covered. The side covered with the insulating
layer i5 the inside sur~ace of the device and is the side
intended to be placed against the body surface during service.
me other side (the outside of the device) is covered with a
fabric layer treferred to herein as the "outside" or `'other"
of ~protective" which is preEerably fabric and protects the
plastic. The insulating layer is bonded to the plastic and
the outside fabric layer is bonded to the plastic sheet
member. The outside fabric layer is preferably between about
and 22 mils thick.
~n accordance with one embodiment, an integral
formable orthopedic device comprises a plastic sheet member
and integral therewith an insulating layer on one side of
said plastic sheet member, and a protective layer on the
other side; said plastic sheet member being at least about
40 mils thick, and having a tensile strength at yield of at
least about 2,000 psi, a flexural strength of between 3,000
and 14,000 psi, a flaxural modulus of between about
0.5 x 105 and 7 x 105 psi, and a Vicat softening point of
between 60C. and 80C.: said insulating layer being at least
about 10 mils thick and having a coefficient of heat transfer
below about 2 cal/secfcm2/cm/CxlO~4.
In accordance with a further embodiment, a shaped
body consists o;E a plastic sheet member of a thickness of 50
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to 120 mils, a flexural strength of 3,000 to 14,000 psi, a
flexural modulus of 0.5 x 105 to 7 x 105 psi and a Vicat
softening point of 60C to 80C, an insulating layer having
a thickness of at least 10 mils and a coefficient of heat
transfer below 2 cal~sec/cm2~C x 10 4 on one side of said ,
sheet member, and a protective layer on the other side of
said sheet member, said sheet being shapable to its final
contours by heating to a temperature of 120F to ~00F at
said protective layer.
In accordance with a still further embodiment, an
integral orthopedic device comprises a central plastic sheet
member having one side covered with an insulating layer and
the other side covered with a fabric layer, both OL said layers
being bonded to said plastic sheet member; said plastic sheet
member being between 50 and 120 mils thick, and having a
tensile strength at yield of a~ove about 2,000 psi, and an
elongation at yield of between 3% and 30%, a flexural strength
of between 3,000 and 14,000 psi, and a flexural modulus of.
between about 0.5 x 105 and 7 x 105 psi, said insulating layer
being between about 10 and 250 mils thick, said other fabric
: layer being about 4 and 22 mils thick and functioning to protect
said plastic layer; and said orthopedic device being formable
at temperatures above about 120F.
In accordance with a still further ~mbodiment, an
orthopedic device comprises a central plastic sheet member .
having one side covered with an insulating plastic foam layer
and the other side covered with a high temperature fabric :
selected from the group consisting of stabilized nylon stabil-
ized polyester and blends thereof, said fabric layers being :~:
bonded to said plastic sheet member, said plastic sheet member :
being between 50 and 120 mils thick, and having a tensile :
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strength at yield of between about 2,000 and 10,000 psi, and
an elongation at yield of between 3% and 30%, a ~lexural
strength of between 3,000 and 14,000 psi, an~ a flexural
modulus of between about 0.5 ~ 105 and 7 x 105 psi, said in-
sulating foam layer being at least about 10 mils thick, said
fabric layer being at least about 4 mils thick and ~unction-
ing to protect said plastic sheet member: and when said device
is heated by the application of heat to the fabric side and
said plastic sheet member is heated to temperatures above
about 300F., said orthopedic device has thermal characteristics
such that it may be shaped and molded for a period of at least
about 4-1~2 minutes be~ore it solidifies.
In accordance with a still further embodiment, an
orthopedic device formable at elevated temperatures comprises
a central plastic sheet member having one side covered with an
insulating plastic foam layer and the other side covered with
a fabric which will not tend to distort the plastic sheet
member when said device is formed, said layers being bonded to
said plastic sheet member, said plastic sheet member being at
least 50 mils thick, and having a tensile strength at yield of
above about 2,000 psi, a flexural strength of between 3,000 and
14,000 psi, and a flexural modulus of between about 0.5 x 105
and 7 x 105 psi; said insulating layer being at least about
10 mils thick: and said fabric being at least about 4 mils
thick and functioning tc protect said plastic sheet member.
BRIEF DESCRIPTION OF ~HE DRAWINGS:
Fig. :L is a rectangular blank having a construction
in accordance w:ith the present invention.
Fig. ;2a is an enlarged cross section along the line
2-2 of Fig. 1 of one embodiment of the invention.
Fig. 2b is an enlarged cross section along the line
2-2 of Fig. 1 of another embodiment of the inventionO
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Fig. 3 is a perspective of a formed back support
having a construction in accordance with the embodiment of
Fig. 2a, and
Fig. 4 is a perspective of a formed arm splint havin~
a construction in accordance wi~h the embodiment of Fig. 2a.
When the insulating layer is a fabric, it may be a
woven, felted, matted, batted or knitted fabric. When it
is a woven fabric, it is preferably between about 10 mils
and 22 mils thick. Some fabrics, e.g., felt, may be con-
siderably thicker and provide cushioning. The preferred in-
sulating fabric is a woven blend, preferably 50:50, of a
high-temperature aromatic polyamide, now generically class-
ified as an aramid, and a high-temperature cross-linked
phenol-formaldehyde fiber~ such as the no-burn fabrics
marketed by Collins & Aikman Corp~ ~,hich are blends of 50%
Kynol and 50/O Nomex. Nomex i5 a trademarked product of the
Du Pont Company and is the high-temperature aromatic polyamide.
Kynol is a trademarked product of the Carborundum Company
and is a cross-linked phenol-formaldehyde fiber, such as
that described in USP 3,650,102. An aramid fabric may also
be used~
me insulated fabrics may be used in weights of
about 4 oz. per square yard, up to about 16 oz. per square
yard. The preferred wei~ht is about S to ~ oz. per square yard.
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The insulating layer preferably should have a co-
efficient of heat transfer below about 2 Cal/sec/cm2/cm/CxlO 4,
and more preferably below about 1.~ cal/sec/cm2/cm/C~10 4.
~ en the insulating layer is a fabric layer, it is
preferably affixed to the central plastic member with an
adhesive, preferably a thermoplastic adhesive. Since
relatively high shaping and molding temperatures, e.g., 400F,
may be used to shape the orthopedic device 9 the thermoplastic
adhesive should be one which will remain bonded to the fabric
and to the central plastic member at the temperatures
used to heat and form the device. It is preferred that it
should retain said property at temperatures above 200F and
~or an added safety factor, it is preferred that it should
retain said property at above about 350F for devices which
~ill be shaped before services.
The outside adhesive may be a polyurethane; pre-
ferably a flexible thermoplastic polyester type polyurethane
adhesive. This material also has the advantages of good
resistance to perspiration, washing and dry cleaning. Al-
though the polyester type polyurethanes are preferred,
polyether types may also be used. mermosetting polyurethane -
adhesives may also be used, such as hydroxyl terminated
hexanediol adipate polyester cross-linked with about 4%
of 4,4'-diphenyl methane diisocyanate, which is preferably
halogenated to improve its flame retardancy.
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An e~truded polyester sheet about 2 1/~-3 mils
thick is also a preferred adhesive. It is positioned between
the central plastic sheet and the fabric layer and the
materials heated to about 350F at a pressure of 1-2 psi
to affix the fabric to the central plastic member.
Alternate but less preferred adhesives include the
acrylates, such as polyethyl acrylate, polybutyl acrylate,
and polyethylhexyl acrylate; and a polyvinyl acetate homo-
polymer and a copolymer of ethylene and vinyl acetate. me
adhesive may also be blends of the foregoing.
me adhesive may be coated as a thin layer on the
central plastic member and the fabric layer positioned on
the adhesive, usually with the application of pressure. This
will usually result in the adhesive penetrating into the
fabric layer. With a combination of a sufficiently thin
adhesive layer and sufficient pressure during application~
there may be some direct contact of some of the fabric with
the central plastic member.
me fabric, particularly when woven, may be par-
tially or wholly impregnated with a plastic adhesive beforebeing applied to the central plastic layer. The preferred
insulating fabric layers are partially impregnated, with the
impregnating plastic being applied from one surface to a depth
of between about ~.1 mil and 7 mils and preferably between
about 0.05 and 5 mils. This results in a thin coating on the
surface of the fabric, which is applied hot (or heated after
application) and affixes the impregnated fabric to the central -
plastic member.
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The fabric layer may also be bonded to the plastic
member by fusing, i.e., heating until the plastic is viscous,
at a temperature above about 325F, and then contacting the
fabric with pressure so that the surface of the plastic
partially impregnates the fabric and upon cooling is bonded
thereto.
The insulating layer may also be a plastic foam
layer. The foam layer provides sufficient insulation so that
the outer surface of the foam layer may contact the person
without severe discomfort while the plastic sheet member
is still soft and usually at a temperature substantially
in excess of about 120-130F. The insulating foam layer
may also function to cushion the portion of the person against
which the orthopedic device is applied.
Since foam layers may be produced having substantially '`
differing insulating characteristics and since the amount of
padding desired varies in different applications, the thickness
of the foam layer may vary from as little as about 10 mils
up to about 300 mils. For most service applications in
which some cushioning is desired and/or is not detrimental,
foam layers having a thickness of between about 125-250 mils
are preferred. Even thicker layers, e.g., up to about
500 mils, may be useful to pad a portion of an orthopedic
device which will contact a boney portion of the person,
particularly when pressure may be applied by this boney
; portion against the orthopedic device~ In some
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applications in which very precise positioning of the body
portion without the possibility of movement is desired,
relatively thin foam layers e~g., between about 25 and 75
mils thick are useful. In some applications, a thin foam
layer may be used lar~ely because there is no further advantage
to a thicker layer and the thin layer would be more economic.
It is preferred that the foam layer should be
relatively stiff so that it does not readily compress under
pressure. mis has the dual advantages that the insulating
characteristic of the foam is retained when the foam layer
is under pressure. This is particularly important since the
orthopedic device is usually "pressed" against the body
when it is formed. A relatively stiff foam layer is also an
advantage in that it provides more accurate positioning and
minimizes the amount of permissible movement of the body
portion against which the orthopedic device is applied. me
foam layer comprises a cellular structure having a great
many pores in the plastic material. The foam may be of a
closed pore construction or of an interconnected (open)
pore construction, or a combination of both as is the usual
instance. me relative stiffness of the foam is preferably
controlled by the selection of polymer constituents which
; produce a relatively stiff foam.
When the orthopedic device is heated su~ficiently
so that it will remain soft for several minutes during which
it is shaped and formed, the plastic sheet member is
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usually heated to a temperature well above 200F and is
often heated to temperatures of at least 300F and sometimes
up to as much as about 350-375F. The insulating foam layer
must remain stable at the temperature to which the orthopedic
device is heated. If the foam layer is not stable at these
temperatures, the cellular structure would collapse as a
consequence of viscous flow, particularly when pressure is
applied. Since destruction of the cellular structure would
impair the insulating characteristics of the foam and also
the cushioning characteristics of the foam, those foàms which
are stable at above 200F are preferred and those foams
~hich are stable at temperatures as high as at least 300F
are particularly preferred.
It is preferred that the foam layer should not
support combustion, i.e., not burn, or that it should
have at least as good flame-retardant characteristics as
the plastic sheet member which is preferably a polyvinyl
chloride composition. It is preferred that the foam layer
should not support a flame in the absence of an external
flame.
The preferred materials for use as the foamed layer
ara those which are (i) rire-retardant and (ii) stable
at temperatures up to about 200F, and preferably up to
about 325F. ~he foam materials that meet these char-
acteristics are thermosetting materials, or if they
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are thermoplastic, very high temperature thermoplastics.
The foam should also be sufficiently flexible so that it
may be bent during forming, and is preferably resistant
to perspiration and washing, and even dry cleaning.
The following are the preferred materials for
forming the foam layer:
(1) Polyolefin foams such as prepared from poly-
ethylene, cross-linked polyetllylene and polypropylene.
Characteristics of polyethylene foams are disclosed in
the Journal of Cellular Plastics, January, 1969, at pages
46-S0, Particularly preferred are fire retardant poly-
olefin foams, such as fire retardant polyethlene. A
useful method for fire retarding polyethylene and other
polyolefins is to incorporate into the polymer fire
retardant additives such as the Diels-Alder adducts of a
hexahalocyclopentadiene, such as hexachlorocyclopenta-
diene. Particularly useful adducfs for this purpose are
disclosed in U. S. Patent 3,403,036 and British Patent
~o, 1,305,834. A metallic additive such as antimony
trioxide is also desirably incorporated in the polymer
together with the disclosed adducts,
(2) Polyurethane foams such as those prepared from
polyether polyols or polyester polyols and mixtures
thereof. me polyether urethanes are preferred and
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especially preferred as the fire retardant polyether
urethanes. The polyether urethanes can be rendered fire
retardant by the incorporation of non-reactive additives,
usually phosphorus-containing or halogenated compounds,
but fire-retardant concentrations are held at low levels
to prevent degradation of foam properties. `A typical
non-reactive additive is a chlorinated phosphorus-
containing ester produced by Monsanto Chemical Company
under the tradename Phosgard 2XC-20. Reactive compounds
can aiso be included in the polyether urethanes to pro-
vide fire retardance. This method is disclosed in U.S.
Patents 3,278,580 and 3,391,092. The latter method
involves utilization of chlorendic acid as the basic
componentin the formation of the polyether polyol.
Another approach is a system of post-treating flexible
foams with fire retardants. me system involves soaking -
the finished foam in aqueous suspensions of inorganic
flame retardants such as magnesium ammonium phosphate
and water-soluble binders that are water resistant after
drying. After the foam has dried, the flame-retardant
characteristic is permanent and there is no loss of
foam properties. Another approach to fire retarding the
polyether urethane foams involves the production of `'high
resilience" foams such as disclosed in Journal of Cellular
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Plastics, July/August, 1972, at pages 214-217. Addi~
tional use~ul fire retardant urethane foams utilizing
additives such as tris(dibromopropyl) phosphate and
tris(dichloropropyl) phosphate, are disclosed in
Journal of Cellular Plastics, November/December, 1970
at pages 262-266 and Journal of Cellular Plastics,
May/June, 1972 at pages 134-142. Fire retarded poly-
ester-urethane foams are also useful such as those
disclosed together with additional polyether urethane
foams in Ind. Eng. Chem. Prod. Res. Develop., Volume
11, No. 4, 1972 at pages 383-389. Additional fire
retardant urethane foams are disclosed in the Journal
of Cellular Plastics, September~October, 1971, at pages
256-263.
(3) Fire retardant ABS foams (acrylonitrile-
butadiene-styrene) are prepared in fire retardant
form by preparing the ABS compositions, for example,
composed of 30% acrylonitrile, 35% butadiene, and 35%
styrene, as is well known in the art. The fire retardant
materials and processes for incorporating them into the
ABS compositions are essentially the same materials and
processes as those described hereinbefore for incorpor-
ation into polyolefin foams.
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~4) Fire retardant polyester foams are also suit-
able. Polyester foams generally are formed by reacting
a polyol, generally a polyester polyol or polyether
polyol with a polycarboxylic (preferably a dicarboxylic)
acid such as adipic acid or sebacic acid. Typical
polyols include butanediol and polytetramethylene ether
glycol~ Fire retardant properties may be incorporated
into the polyester by preparing the polyester and then
soaking the finished foam in aqueous suspensions of
inorganic flame retardants as described hereinbefore
: in connection with the polyurethane foams. The fire
retardant properties also may be built into the foam
by incorporating chlorendic acid as a partial or total
replacement for the carboxylic acid, as disclosed in
USP 2,606,910. The polyester foams are generally
foamed by admixing a blowing agent utilizing similar
technology to that used in forming polyolefin foams.
(5) Although polyvinyl chloride foams generally
are not stable at temperatures above 160F, a polyvinyl
chloride composition alloyed with an acrylonitrile-
butadiene-styrene terpolymer may be used in applications
wherein stability above about 200F is not required.
Post-chlorinated polyvinyl chloride foams are stable
at elevated temperatures. mese are hi~hly stabilized
thermoplastic material~ and form stable foams.
(6) Suitable foams may also be formed from
fluorocarbon elastomers which at present are very
- expensive,
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(7) Additional foamed plastics include acrylic,
cellulose acetate and epoxy foams, such as disclosed
in 1974-1975 Modern Plastics Encyclopedia at page 720.
The foam layers are formed using the foam
producing production methods which are well known in
the foam material technology, e.g., Modern Plastics
Encyclopedia, 197~-1975, Vol. 51, ~o. lOA, (Oct. 1974)
pages 125-155. The precise foam constituents and pro-
duction techni~ue varies somewhat dependent upon the
specific polymer~s) which forms the basic foam material.
us, the polyurethanes may be foamed in the presence
of small amounts of water which react with the ico-
cyanate to produce carbon dioxide, without requiring
additional foaming agents. In some instances foaming
gases or gas-producing materials are used. Mechanical
frothing may also be used in the production of certain
foams, e.g., polyurethanes and polyesters. The polymer
is dispersed in water, e,g., 40-65% by weight o~ solids
and mechanically mixed by a high shear mixer to incor-
porate air and is then cast on sheet material and dried
by heating to remove water. -
The foam layer may be produced directly on
the plastic sheet member or on a fabric layer using
the direct coating process. The transfer coating
process also may be used in which the foam material
is kni~e coated on
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release paper (generally silicone treated paper) and then
transferred to a fabric or -the plastic sheet member or even
a metal substrate and cured. In the usual instance it is
contemplated that the foam layer will be formed on a fabric
or an inert high temperature substrate such as a polished
metal and cured. If a fabric is used, it should be a high
temperature stable fabric, such as the high temperature
stabili2ed polyesters and/or nylons. High temperature stab-
ilized polypropylene such as a needle punch polypropylene
fabric about 8-10 mils thick is also suitable. Alt~ough a
fabric may be used, it is not necessary in order to produce
a pleasing and even a decorative effect. These may be produced
directly on the surface of the foam using printing or emboss-
ing rolls.
The foam layer may be fixed to the plastic sheet
member by conventional methods such as the use of adhesives,
application of pressure, ~lame bonding, etc. me bonding
method selected depends upon the composition of the plastic
sheet member and the composition of the foam layer. When
the plastic sheet member is a polyvinyl chloride composition,
and the foam layer is a polyolefin foam or an ABS foam, the
preferred method of bonding utilizes ethylenevinylacetate
copolymer as an adhesive to form the bond. Polyether
polyurethane foams and polyester foams are also preferably
bonded to polyvinyl chloride sheet composition using an ad-
hesive, preferably a thermosetting polyurethane such as a
hydroxyl terminated hexanediol
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adapate polyester cross-linked with about four p~rcent of
4,4l-diphenol methane dioscyanate, The said thermosetting
polyester urethane adhesive is pre~erably halogenated to
further the ~lame-retardant characteristics of the ortho-
pedic device. The said thermosetting polyurethane adhesive
is also useful for bonding polyvinyl chloride foams to
pclyvinyl chloride sheet material.
Polyester polyurethane foams are preferably flame
bonded to polyvinyl chloride sh~2et material.
Foam layers, preferably those having a coarse
interconnected cellular structure tat least at and near
the skin) may be fixed to a thermoplastic sheet member by
haating the thermoplastic sheet member until it has softened
and contacting the sheet member and the foam layer under
pressure, e.g., by passing the heated thermoplastic sheet
member and the foam layer through rolls,
The strength and flexural properties of the ortho-
pedic device at ambient tQmperatures are largely contributed
by the plastic central member. This m~mber is strong and has -
the ability to be resili~nt in some configurations and sizes~
It has the ability to be substantially rigid in specific con-
figurations, i.e,, O-sections, L-sections, U-sections, etc.
A deYice may include several different configurations and be
substantially rigid in a specific area and quite resilient in
another area thereof.
The versatility of the orthopedic devices is illus
trated by the following properties of the plastic sheet.
Different conf:igurations were prepared from sheet t90-93 mils
thick~ having l,he composition illustrated hereinafter. T~e
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sheet was 6 3/8 inches long,
An "o" configuration was prepared with a radius of
tube of 13J16 inches. The tube was held with clamps at each
end, It was supported on two focal points 4 inches apart at
the bottom, and the load appliecl from the top to the center
of the tube, The deflection follows:
Machine Deflection(a)
in Inches Load in Pounds
0.1 49'5
0.2 51,2
0-3 80.5
0-4 104.0
0 5 125.0
0,6 142.0
(a) The machine deflection includes bending of the
tube over its entire length, and flattening of the tube at all
three focal points.
A "U'` configuration was prepared with a 2 3/8 inches
width of configuration and a 29/32 inch radius of bend. The
arms of the '`U'` were mounted parallel to the horizontal (held
in vice) and the load applied to the upper arm. A constant
load test provided the following~
Points at which Constant Load
(1 lb.) was Applied, Measured Deflection in Inches at
in Inches from Center of '`U'` Constant Load (logarithm)
1.15 0.050 '~
1.75 0.095 -
2.75 0.135
3.75 0.175
` 30 4.75 1.145
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A constant deflection test provided the following
data:
Points at which Constant Deflec-
tion (0.45 inches) was Obtained, Load in Pounds at
Measured in Inches from Center Constant Deflection
_ of "U" _ (loqarithm)
4.75 0,30
3.75 0.60
2,75 1.1~
1.75 8.60
1,15 10.73
T~o "L" shaped configurations were prepared by hold-
ing in a vice vertically and-bending~to form a right angle.
The load was applied vertically and placed on horizontal arm.
The results of a constant load test on a sample
having a 2 7/16 inches width of configuration and 1/4 inch
radius follows:
Points at which Constant Load D~flection in Inches
(2 lbs.) was ~pplied, Measured at Constant Load
in Inches from Center of Bend (lo~ar-ithm? -- -
0.5 0,010
1.0 0,025
1.5 0,070
2,5 0,280
3 5 0.680
4-5 1.150
The results of a constant deflection test on a sample
having a 2 3/8 inches width of configuration and a 29/32 inch
radius follows:
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Points at which Constant Deflec-
tion (0.35 inches) was Obtained, Load in Pounds at
Measured in Inches from Center Constant Deflection
of Bend (loqarlthm) _
4-5 0,50
3-5 1.00
2.5 2,27
1.5 12.00
1.0 40,00
The physical properties of the plastics vary some-
what with the thickness of section tested. Specific physical
properties such rigidity and/or resilience of the orthopedic
support vary with the thickness and overall size dimensions
o~ the plastic central layer. The central plastic layer is
usually between about 50 mils and about 120 mils, although
thicker layers, e.g., up to about 250 mils thick, may be
utilized for large sections, such as a major body cast, e.g.,
about 200 mils thick, where substantial rigidity is required
to support a large weight~ Thick sections, e.g., about 150-
170 mils, would also be used to provide orthopedic devices
used to precisely position the body portion for radiation
therapy, Devices (in blank form, i.e,, flat) used for pre-
paring back supports, are preferably about 65-80 mils thick.
Blanks for splints and braces are preferably about 80-120 mils
thick. m e preferred blanks for highly shaped casts may be
of a variety of widths dependent upon the final configuration
and service requirements. When thin devices, e.g., 40-50 mils
of plastic central member, are used, additional strips or
pieces of plastic sheet may be fixed to the outside surface
to reinforce the device.
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The plastic preferably has a tensile strength (at
yield) of between 2,000 and 10,000 psi and more preferably
hetween 5,000 and 8,000 psi (ASTM D-638). The central plas-
tic layer is relatively stiff as reflected by a percent
elongation at yield of between about 3 and 3~/0 and prefer-
ably between about 4 and 8%. The properties to yield are
more important than to rupture since the properties should
not exceed yield in service.
The flexural strength (ASTM-790) is between 3,000
and 14,000 psi and preferably between 8,000 and 12,000 psi.
The flexural modulus (ASTM-790) is between 0.5 x 105 and
7 x 105 psi and preferably between 2 x 105 and 5 x 105 psi.
me notched I~od ( ASTM D-256) in foot-pounds per inch is
between 0.3 and 30 and preferably between 0.5 and 15~
The Rockwell hardness is between 15 R scale and
55 D scale and preferably between 90 and 100 R scale. The
Vicat softening point (ASTM D-1525-70~ is between 60C and ~ .
80C.
A sample o the preferred impact modified poly-
vinyl chloride plastic member which is illustrated in the
Example has an average tensile (+ 100 psi) at yield of about
7,550 psi and at rupture of about 3,800 psi ~ASTM D-638),
m e average (+ 0.5% percent elongation at yield is 5% and
the average percent elongation at rupture is 14.2%, The
average flexural strength is 10.8 x 103 psi and the flexural
modulus is 4.1 x 105 psi (ASTM d-790),
,
: ,' '
.
- 20 ~
- : ~ . .. :: :, , . : ., -
- . . . : : . ., :
- .: ., . . . ~. . . . . , : . ~ :
~'7~
Another sample of the same composition had a ten-
sile strength at yield of 6,785 psi, an elongation at yield
o~ 5.6%, a flexural modulus of 3.94 x 105 psi, a flexural
strength of 11,612 psi; a Rockwell R of 94, a Vicat of 74C,
and a notched Izod of 0.91 foot pounds per inch.
Another sample of the same composition which had
b~en severely worked during processing, but found operative
had a tensile strength at yield of 3,620 psi, an elongation
at yield of 4.5%, a flexural modulus of 1.06 x 105, a flex-
ural strength of 3,724 psi, a Rockwell R of 19, a Vicat of
63C; and a notched Izod of 12,5 foot pounds per inch.
m e central plastic member may be formulated from
various polymer systems, such vinyl-chloride-propylene co-
polymers, vinyl-chloride-ethylene copolymers, or the corres-
ponding interpolymer containing diallyl maleate, It is
preferred to utilize an impact modified polyvinyl chloride
~VC) composition utilizing a PVC resin having a number
average molecular weight of 20,000-23,000. m e composition
contains between about 10 and 14 parts of an impact modifier,
between 1 1/4 and 2 parts of lubricant, and between 7 lJ2
and 8 1/2 parts of a plasticizer, per 100 parts of polyvinyl
chloride homopolymer resin, The composition will also con-
tain stabilizers ~6-9) parts and various processin~ aids
(1,5-2,1 ~arts) and usually pigments (up to 5 parts),
- 21 -
'- ' ''.:'' , ' :' ,
~o~z~
A pre~erred PVC composition and exemplified compo-
sition follow:
Preferred Preferred
Range Composition
COMPO~E~TS (parts) (~arts)
PVC homopolymer resin (20,000-23,000) 100 100
impact modifiex (methylmethacrylate-
butadiene-styrene polymer10 - 14 12.0
processing aid (acrylic type)* 1.5- 2,1 1.8
lubricant
blend of olefinic mono(~lyceride
and hydrogenated olein 1 - 1.5 1.25
tri-stearyl citrate 0.25- 0.35 0,3
plasticizer (di-2-ethylhexyl phthalate) 7.5- 8.5 8.0
stabilizer boosters
epoxidized soybean oil 4 - 6 5,0
mixed di- and tri-nonylphenyl
phosphite 1.25- 1.7S 1.5
polyvinyl alcohol 0.05- 0.08 0.0675
stabilizers
calcium stearate 0,24- 0,30 0.27
stannous stearate 0.37 - 0.43 0.40
zinc stearate 0~28- 0.34 0.31
pigments 2.5 - 3,5
rutile grade TiO2 3.2S
Hosterperm Red 0.0054
Indofast Orange 0.0135
* Rohm & Haas K-120 N
':
., -: , ~
- 22 -
.. .. . .. .. .. . . . . . . .
A sheet of the polyvinyl chloride having a
thickness of about 80-90 mils was prepared from small
pellets about 1/8" x 3~16" in diameter. ~he pellets
were heated in an extruder and the resin composition
extruded in the form of a rope-shaped material of a
diameter of about 1~2" which is then milled in rollers
and calendered into sheet about 15-20 mils thick. Four
sections of such sheet were laminated together in a
press with a heated die to form sheets about 80-90 mils
thick. The physical properties of this test sheet were
reported hereinbefore. Additional details concerning
the said plastic compositions and the manner of produc-
ing them are disclosed in U. S. Patent 3,906,943, issued
September 23, 1975, entitled "ORTHOPEDIC DEVICE" and
; naming Elmer M, Arluck as the inventor,
The polyvinyl chloride sheet material may be
formed in production by heating the small PVC composition
pellets in an extruder and directly extruding in sheet
form having the desired thickness. An alternate pro-
cedure is to mill and calender rope-shape material of a
diameter frQ~ about 1~2" to 4". Sheet material taken
from such processes and particularly direct extrusion
is stressed and is preferably stress relieved by anneal-
ing at temperatures of about 320F, It is possible to
anneal simultaneously with the application of an adhesive
or an adhesive and fabric.
- 23 -
,
.~ 1.
.
~ 3~99
The outside layer which is preferably fabric (but
could also be another material such as a metallic layer)
protects the plastic surface from damage during shipment,
storage and handling of the flat orthopedic device before
it is molded and also to protect it after it has been
shaped. If a heating element is used, for example, a hot
iron, directly in contact with the orthopedic device, the
outside fabric layer serves to prevent adherence of the
plastic to the heating element,
This outside layer also functions together with
the insulating fabric layer to maintain the coherency of
the orthopedic device when it is heated to elevated tem-
peratures. Since the outside fabric layer is bonded to the
plastic, it will be in tension when the orthopedic device
is shaped into a curved with the outer fabric layer on the
outside of the curve. It is, therefore preferably of a
resilient or stretch material which will not apply pressure
on and tend to distort the plastic layer at ambient and
particularly at elevated shaping andJor forming temper-
atures,
During heating, the outside fabric layer may be
subjected to very high temperatures. The preferred fabrics
are those resiStant to prolonged heating at 250F and short
term heating to substantially higher temperatures, These
high temperature resistant fabrics include the high temper-
ature stabilized nylons, the high temperature stabilized
polyesters, the Spandexs (polyurethanes), the aramids; such
~ 329~
as Nomex, high temperature acrylics, the aforedescribed
Collins and Aikman blends of 50% Kynol and 50% Nome~ and
particularly the lighter weight fabrics; and linen, The
said nylons, polyesters, and aramids, are preferred.
For devices which are not to be heated to ele-
vated temperatures, i,e., they are available in blanks
generally conforming to the desired end shape, and which
are only heated for forming, lower temperature fabrics,
such as cotton and wool may be used.
me outside fabric layer is at least about ~ mils
thick, and preferably between about 4 and 22 mils thick and
most preferably between about 10 and 15 mils thick. It is
preferably affixed to the plastic central member by an ad-
hesive such as a thermoplastic polyurethane resin, Even
thinner outside layers may be used, e.g., only 1-2 mils of
metal plated or laminated on the plastic sheet member, The
protective layer need not cover the entire surface of the
one side of the plastic sheet, e.g., portions of the plastic
may be covered by reinforcing plastic sheet strips.
; 20 The outside fabric layer may be fixed to the cen-
tral plastic layer. Orthopedic devices have been prepared
by first affixing an insulating fabric layer to the central
plastic member by passing a three-layered material comprising
the central plastic member and extruded polyester film of
about 2 1/2 - 3 mil thickness and the 7 oz. Collins & Aikman
fabric described hereinbefore through a Reliant roll press
'.
- 25 -
~ 9q~
which was at 350F and applying 1-2 psi for 18 seconds.
The extruded polyester film was a thermoplastic. The
other fabric film, the 4 oz. Collins & Aikman fabric des-
cribed hereinbefore, was then affixed to the other side of
the central plastic member by passing the aforedescribed
insulated fabric coated centra:L plastic member together
with said fabric and an interposed 2 1/2 - 3 mil sheet of
the polyester film through the Reliant roll press under
the aforesaid conditions. It is preferred to produce the
orthopedic device by passing the two outer layers and the
central plastic member and the respective adhesive layers,
which may be preapplied to the fabric or plastic foam,
through the roll press simultaneously to produce the inte-
gral orthopedic device in a single pass. The blank ortho-
pedic device may also be prepared by extruding the plastic
sheet member onto a coated fabric or even coextruding the
fabric layers and the plastic sheet together with the
intervening adhesives,
At the shaping and forming temperatures the ortho-
pedic device is readily cut. The cutting may be carried out
` by shears, for example, a scissors or other sharp edge,
Those orthopedic devices having both sides of the plastic
member covered by fabric layers retain integrity even at
elevated temperatures, When it is desirable to carry out ex-
tensive shaping and forming of the orthopedic device such as
forming a coil by wrapping various layers of the orthopedic
.' ~ .
,:
- 26 -
:10~
device about each other in a spiral, the temperatures may
be elevated, e.g., up to about 250-400F, At these temper-
atures the device maintains its integrity but becomes highly
pliable. The orthopedic device may be cut and the plastic
does not run out from between the outer layers. When the
orthopedic device is heated to such high temperatures and
removed from the source of heat, it may be shaped and molded
and formed over a period up to about 6-10 minutes, m e rough
shaping is carried out as the orthopedic device begins to
cool from this elevated temperature. When the outer surface
of the insulating layer is cooled sufficiently, it may be
pressed against the body portion to be formed into its final
shape, generally under finger pressure. After the ortho-
pedic device is applied against the body, there is still
sufficient time during which final molding to conform to the
desired body and/or device shape may be carried out.
The orthopedic device may be heated in a constant
temperature fluid bath, such as a water bath or a hot oven
or radiant energy. It is preferred that heat be applied
only to the side of the orthopedic device which will not be
applied a~ainst the patient. This may be accomplished by
radiant heat, a hot air gun or hairdryer and preferably
because of their ready availability, a hot plate or tray
and an iron in the form of the familiar hot tray, home iron
or even a special round or curved iron. Surprisingly, it
has been found that the hot surface of an iron which may
' be as hot as 300-500~F, may be applied to the fabric layer
- 27
- . ' ' ~-,: ' ,
~3~9~
of the orthopedic device and heat it to temperatures at
which it becomes extremely pliable so that it may be cut
and shaped to extremely complex shapes. The heat source
is removed and/or intermittently applied and the ortho-
pedic device applied against the body portion and molded to
the desired shape, The molding or forming may be carried
out by finger pressure, The person applying and forming
the orthopedic device may wear gloves, When a hot tray is
used and the device covered by a protective dome, a temper-
ature of 200F will over a period of time furnish sufficient
heat so that the device will remain formable for the desired
working time,
The upper temperature limit which may be applied
against a portion of the human body varies dependent upon
the area of skin in contact with the heat, the time of con-
tact, and the individual tolerance to high temperature, For
; the purpose of applying orthopedic devices, the temperature
should not be above about 120-125F for short term contact
and preferably below 120F for contact of several minutes,
When the orthopedic device in blank form is pre-
cut and requires only forming, it may be heated to a temper-
ature between about 165-225F from one side, and when the
outside of the insulating fabric layer is sufficiently cool,
applied to the patient's body and formed into the desired
contoured shape,
- 28 -
7;~'~99
The central plastic member of -the orthopedic
device exempli~ied herewith solidifies at a temperature
of about 129-130F, As a consequence, it is necessary
that the t~mperature of the plastic central member should
be above about 130F during forming. Since application
of this temperature to the pat:ient's skin for more than a
very short time is uncomfortable and possibly dangerous,
the outer temperature of the insulating fabric layer
should be at least 25F cooler than the temperature of the
plastic central member during forming, and is preferably
at least 30F cooler. It is even more preferred that the
- outar temperature be at least 35~F or 40F cooler than the
plastic. The foregoing particularly applies during the
plastic forming range of 130F up to about 160F. The
temperature at which the plastic sheet members softens per-
mitting the orthopedic device to be formed may be varied
from about 120-123F, up to about 1~5-155F by varying the
composition of the polyvinyl composition comprising the
central plastic sheet. The aforenoted temperature differ-
ence may be larger, e.g., at least 50 or 60~F when the
device softens at a higher minimum temperature, e.g., above
about 145-155~F. A foam insulating layer is particularly
suitable.
In a preferred embodiment of the invention, the
heat is applied against the side of the orthopedic device
covered by the outside fabric layer. For some service condi-
tions it is contemplated that both sides of the plastic
central member may be covered by insulating material. This
- 29 -
,, . . ~ .
-' ' :, :' ' .' ' ' - . ' . . .~ .~ , . ,
~ 3~9~
would permit the entire member to be heated to an elevated
temperature and retain the heat for a longer period of time.
me molded orthopedic device may be in many forms
dependent upon the intended serv:ice and particularly the
portion of the body to which it is applied. The orthopedic
device when manufactured will be in the form of sheet
material. For most purposes, these sheet blanks will be in
a variety of sizes such as squares from about 4 inches on
a side up to about 2 feet on a side and even larger sizes,
e g. 2'x4'. Rectangular and even oval or round blanks may be
prepared. These blanks will have the central plastic member
in sheet form with the insulating layer bonded on one side and
the other layer bonded on the other side~ Such blanks may have
a total overall thickness somewhat less than the sum of the
thickness of the plastic central member plus the two outer
layers as a result of the manufacturing process which involves
the application of pressure either in the form of a press or
more usually in the form of pressure rolls.
The invention is further illustrated by the following
Example and drawings:
Fig. 1 of the drawing illustrates a rectangular-
shaped blank (flat orthopedic device) 10 having a protective
fabric layer 13 on one side of the plastic sheet 12 and the
insulating layer 11, 20 on the other side.
Figs. 2a and 2b illustrate two embodiments of the
invention along line 2-2 of Fig. 1.
30 -
- ~ ...
'`, ,, : . . ,, . , ~. ,. ,...... . .~ , .... .
~Q~3Z99
Fig. 2a illustrates a preferred embodiment of
the invention in which the insulating layer 11 is on one
side of the plastic sheet 12 and the other side of the
plastic sheet 12 is covered by the protective fabric
layer 13. The relative thickness of the layers in all the
drawings is for illustrative purposes only,
Fig. 2b depicts a preferred embodiment of the
invention in which one side of the plastic sheet 12 is
covered by the protective layer 13 and the other side is
covered by the insulating layer 20,
Fig, 3 illustrates a shaped and formed back sup-
port 14 with formed contours such as those illustrated at
15 and 15'. The central portion 19 is relatively fixed and
supports the spinal area and portions 15 and 15' are more
resilient and support the back and related lower body
portions,
Fig. 4 illustrates an arm splint 16 having hand
section 17, wrist section 18, and forearm section 19, with
the insulating foam layer 20 ~not depicted in the edges)
on the inside surface and a protective layer 13 on the out-
side surface.
; The invention is further illustrated in the follow-
ing Examples. All parts and percentages are by weight un-
less specified otherwise,
EXAMPLE 1
;
A flat blank orthopedic device was formed from a
plastic sheet member of a thickness of 91-93 mils and having
...... - .. ,
:~V~
the composition set forth in the righthand column of the
table hereinbefore was coated on one side with the woven
insulating ~abric which is the non-burning blend of 50%
~ynol and 50% Nomex described hereinbefore. This insulat-
ing fabric had a weight of about 7 ounces per square yard
and was about 1~ mils thick. It was impregnated from one
side with a polyester flexible polyurethane thermoplastic
adhesive to a depth of about 3 mils on one side. A thin
coating remained on the side to which the impregnant was
applied. It was bonded to the plastic member by heating
the impregnated insulating fabric to a temperature of about
325F and then covering the plastic sheet and applying
light pressure. The other side of the plastic sheet was
covered by a knit stabilized nylon ~abric of a thickness
of about 14 mils similarly impregnated with the same ad-
hesive. It was similarly bonded to the plastic member.
EXAMPLE 2
One-hundred parts of a fine powder, e.g., 40-50
microns, of a partially cross-linked polyethylene which will
produce a generally stiff but flexible foam is mixed with
6-10 parts of titanium dioxide pigment and about four parts
of bisazodicarbonamide, and mixed until homo~enous, It then
~as spread in a thin sheet on silicone coated paper and passed
into an oven and heated to 170-190C over a period of up to about
.:
. ~.
. .
lt)~73~9~
ten minutes. The bisazodicarbonamide decomposes liberating
nitrogen and causing formation of foam. The resultant foam
layer is about 125 mils. Another thicker layer was formed to
about 250 mils. The newly formed foam is then cooled
quickly by passage through a cold water trough. The
resultant foam was sufficiently flexi~le to be bent back -
up on itself. Its density is 4.1 pounds per cubic foot.
The p~res are~prèdominantly of the closed type in the area
of the skin.
Samples of sheet of the above foam about 125 mils
thick, and also of 250 mils thick, are adhered to a
sheet of said central plastic member formed from PVC with
the thermosetting polyurethane adhesive described hereinbefore.
The other side of the PVC was coated with the tricot as
descri~ed in Example 1. The resultant device had desirable
orthopedic device characteristics. The disadvantage
was that the polyethylene was not fire re-tardant.
EXAMPLE 3
Example 2 is repeated using a fire retardant composition
comprising 75 parts of polyethylene, ~5 parts of the Diels-Adler
diadduct of hexachlorocyclopentadiene and 1,5-cyclooctadiene, ~i
10 parts of antimony trioxide, 6-10 parts of titanium dioxide, ~-
and about 4 parts of bisazodicarbonamide. A third foam layer
about 50 mils thick is used in place of the thicker layers
of insulating f Dam in Example 2
1~
-- 33
.... , , ' ~'.
: ` . . :
., : . . . , . . : ,
. . . ,, . ~. .
~O~Z99
EXAMPLE 4
Example 2 is repeated substituting for the polyethylene
foam of Example 1, a polyethylene foam having a density of 4.0
- pounds per cubic foot, a thermal conductivity of 0.40 Btu/S~.
ft./hr. degrees F/inch as measured by ASTM D2326, a water vapor
transmission as measured by ASTM C355 of < 0.40 perm-inch'and
a water a~sor ~ ion of < p.50 percent by volume (96 hours)
as measured by ASTM D2842.
EXAMPLE 5
Example 2 is repeated using a cross-linked polyethylene
foam having a density of about 4 pounds per cubic foot, a
thermal conductivity of 0.40 Btu/sq. ft./hr. degrees F/inch
as measured by ASTM D2326, a water vapor transmission of
<0>40 perm-inch as measured by ASTM C355 and a water a
absorption of <0.50 percent by volume (96 hours) as measured
by ASTM D2842.
EXAMPLE 6
Example 2 is repeated using a commercially available
fire retardant polyurethane foam having an ASTM D1692-68
classification of SE (self-ext~nguishing) and a density of
4.18 pounds per cubic foot (67 kg/m ). A foam layer about
25 mils thick is used in place of the thicker foam layer
of Example 2.
EX~PLE 7
:
Example 2 is repeated using a fire retardant
composition comprising 60 parts by ~eight of polypropylene,
:
3~ _
.~ . ~
~ 3~g~
27 parts by weight of the Diels-Alder diadduct of hexachloro-
cyclopentadiene, 1,5-cyclooctadiene, 13 parts by weight of
antimony trioxide, 6-10 parts of titanium dioxide and about
4 parts of disazodiacarbonamide.
EXAMPLE 8
Example 2 is repeated using a flexible polyurethane
foam having a density of two pounds per cubic foot and a
thermal conductivity of 0.3 Btu/sq. ft./hr. degrees F/inch
as measured by ASTM D2326.
EXAMPLE 9
Example 2 is repeated using a high resilience poly-
urethane foam having a density of 2.7 pounds per cubic foot
and a flame resistance characteristic of SE (self-extinguishing)
as measured by ASTM D1692.
EXAMPLE 10
Example 2 is repeated using a flexible polyurethane
foam as prepared in Example 4 of U.S.P~ 3,391,092O
The thermocooling characteristics of the various
components of the orthopedic device when heated to high
temperatures, for example, about 300F. are illustrated in
the following time-temperature profile of a flat (blank) about
6 1/2" x 6 1~2". The central plastic member was about 69
; mils thick. The insulating fabric was the aforedescribed
Collins & Aikman no-burn fabric (7 oz. weight) about
15-18 mils thick. The other fabric was a knit (tricot)
- 35 -
"' '~
~ ~ .
.5
3~
stabilized nylon and polyes-ter blend about 12 mils thick.
Both of the fabrics were applied to the plastic member by
spreading an adhesive on one side of the plastic member and
then applying the fabric and applying a heated iron to heat
the fabric and adhesive to the temperature range to about
350-380F. The adhesive was spread to a thickness of about
3 mils. The insulating fabric was applied using the ther-
moplastic polyurethane adhesive clescribed hereinbefore.
The tricot adhesive was the thermosetting polyurethane des-
cribed hereinbefore containing about ~% of the cross-linking
diisocyanate.
The thermal properties were determined by first
heating the device and then allowing it to cool in air (room
temperature 69-71F) and measuring the rates thereof. The
device was positioned with the tricot fabric face about 3/8
of an inch away from the hot plate and parallel thereto. The
hot plate was measured to have a surface temperature of about -
409F. The device was heated to the temperatures noted in
the following table and then permitted to cool. A
thermocouple T3 was positioned on the central plastic member
face which is bonded to the tricot and a thermocouple T4
was on the side of the plastic member which is bonded to the
insulating fabric. The time-temperature profile follows:
- 36
- -, . ~
: , . - ,. .. . .
~ 3Z~
Time Temperature OF
(minutes) T4 3
Heating 0 82 82
192 209
17 224 234
Heat Source ~emoved 21,5 268 323
Cooling 0.5 263 284
1.0 252 267
1.5 242 251
2.0 227 237
2.5 219 225
3,0 2~6 213
3.5 195 201
4.0 186 192
4.5 177 182
5.0 168 173
5.5 161 166
5.8 157 161
8.0 131 134
10.0 115 118
11.5 106 108
Ph~sical manipulation of the.device established
: that the forming period ended, i.e., the plastic had solid-
ified, when the plastic temperature was about 130F. In
some cases this appeared closer to 129~F which is within
the range of accuracy of measurement, The same device was
reheated several times and each time it solidifies at about
130~F. Other samples softened at somewhat lower temperatures,
e.g., 124F-127F,
This data is consistent with the developmental
experience that the same device may be completely or partially
reformed, and even reshaped, in whole or in part, many times.
..
- 37 -
~ 3~99
This provides means for correcting "fitting" errors, and
also means for adjusting the shape of the device during
its service life. It also provides the possibility of
reusing the device which is particularly important in
the poorer countries. Orthopedic devices having the
insulated foam layer in place of the fabric layer provide
even more forming time with at least as much protection to
the patient.
The aforesaid time-temperature profile establishes
that there was more than eight minutes of shaping and form-
` ing time, i.e., the time starting with the removal of the
heat source, until so~idification oCcurs. Practical testing
of numerous samples having the nylon-polyester fabric on one
side and the no-burn Collins & Aikman insulating fabric on
the other side has established that when the device has been
heated to over 300F and preferably to 325F, there is at
least 7 1/2 minutes of shaping and forming time. Tests with
other experimental devices in which the other fabric is not
nylon-polyester, for example, cotton, have established that
the cooling time tosolidification may be different and
in some cases appreciably shorter, for example, as little
as 4 1/2 minutes.
- 38 ~
. :
~ 3Z~
The actual cooling time for a ~iven device may
vary with the overall thickness and other dimensions of the
device as well as the amount of heating time and ultimate
temperature and the cooling conditions. 1`he devices having
the insulating plastic foam layer, particularly thick layers,
e,g,, 125-250 mils thick, cooled more slowly and provided a
larger temperature differential, e.g., at least 55-60F,
between the outside of the foam layer, and the plastic sheet
member.
Temperature determinations were also made on the
outside of the insulated fabric layer during the time-
temperature profile, and during other hea-ting and cooling
tests. It was found that when using the aforesaid 7 oz.
Collins & Aikman no-burn fabric, the temperature differen-
tial between the outside of the fabric and the plastic was
about 40F, The temperature measurements sometimes indi-
cated a variation of + 10F, but were usually within +5F.
When the "blank" orthopedic device is severely
shaped at temperatures above about 325~F, e.g,, some
portions bent around one axis and other portions bent around
a perpendicular or other intersecting axis, there may be
some displacement of plastic within the outer layers so
that the resultant shaped (and usually formed) device may
no longer be of a consistent uniform thickness.
Some practitioners who apply the orthopedic devices
may wi~sh to outline the shape, particularly when the shape
_ 3~ _
.: . .~: . . , ::.
~ 3~9~
is relatively intricate, in a pattern on the blan]c (flat)
orthopedic device before cutting it into the rough shape
and forming. This may be accornplished in several methods
depending upon the fabrics involved, Certain fabrics,
e.g., the woven blend of Kynol and Nomex described herein-
before, may be marked with a marker, e.g., pen, pencil,
crayon, etc. Alternately, a paper layer may be affixed to
one of the surface layers by a pressure-sensitive adhesive,
me surface of the paper may be marked and used as a pattern
and the orthopedic device cut and shaped. The paper may be
removed immediately after cutting or in some cases desirably
retained until rough shaping is completed. It would then be
stripped from the outer layer.
The orthopedic devices of the present invention
have many advantages. When used as a relatively large sup-
port without severe bending, such as a back support, the
orthopedic device supplies resilient support. When used as
a cast it will immobilize. When used to keep a body part
in bent position such as a knee cage, restraint in only one
direction is required. The orthopedic devices have special
utility for service where adjustment in the shape of the
device is desirable during a protracted period of time.
Thus, as the patient responds to treatment, change in posi-
tion may be desirable. In the past with plaster casts, the
old cast had to be removed and a new cast formed. The ortho-
; pedic devices of the present invention may be partiall~
reshaped even when attached to the body by localized appli-
cation of heat and molding.
~73~
One of the most important uses of orthopedic
devices is support of the lumbo-sacral region of the back.
Immobilization of the lower body area risks a number of ill
effects including shrinkage of tendons, and elasticity loss
and weakening of muscles. The orthopedic devices of the
present invention provide effective support and permit
stabilization and immobilization of the lower spine with-
out the foregoing adverse effects. This results from the
unique combination of physical properties which provide sub-
stantial immobilization by those portions of the device
which are highly contoured and at the same time provide
resilient support by other less contoured portions of the
back support and thereby permit body movement. Because of
the ability to be formed and molded directly upon the patient,
it is possible to provide back supports (which have been
impossible or very difficult to make using prior materials)
which cover relatively diverse and~or large portions of the
back and, in some cases, may overlap around the sides of the
body or over the shoulder.
me orthopedic devices may be used in the veter-
inary field in a manner parallel to their use with humans.
The orthopedic devices may be placed in a pocket or
pouch of a garment which encircles a part of the body and
thereby positions the orthopedic device. For many applica-
tions it will be desirable that the orthopedic device should be
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-- . .. . . .
,, . . . ~
~ 3~
placed directly against the body portion and encircle
it, and therefore it is self attaching, For other appli-
cations, the orthopedic device should have loops or other
means of attachment for belts and other types of bind-
ings such as fasteners identified by the Trade Mark
i'Velcro", etc. These may be affixed to or even incor-
porated into one or both of the fabric layers~ In such
instances they will be affixed to the fabric layer which
is on the side of the orthopedic device away from the
patient's skin, i.e., in most instances the outside fabric
layer. Orthopedic devices may be formed in self-closing
and fastening configurations or may be fastened in any
and all ways known in the art today.
The orthopedic devices may be provided as flat
- blanks for molding and shaping by the ultimate user.
They may also be provided in preformed shapes, such as
a series of preformed back supports which will generally
conorm to the body portions of the appropriate size.
These orthopedic devices would have the advantage over
other preformed devices in that final adjustment to
individual variations may be made. mey will also have
the advantages over prior orthopedic devices in their
combination of rigidity and resilience in different
directions.
:~:
- 4~ -
:~ : :
.. . . . :- . . ..
.
~ 3Z9~
The orthopedic devices are also useful when utilized
to position the body (or a portion thereof) very accurately
for radiation treatment.
The orthopedic devices having a foam outer surface
may be used as per se, or as part of another orthopedic device
to cushion or otherwise protect a portion (usually a boney
portion) of the body~
Although the orthopedic devices will generally be
conformed to the shape of the body, they may sometimes be
shaped differently so as to make the body conform to the shape
of the orthopedic device during service, e.g., a correctly
formed arch support for use by a person having a fallen arch.
The discussion hereinbefore is primarily in con-
nection with orthopedic devices which will be attached to the
body. m ey may also be used in equipment which is not attached
to the body but comes into contact with the body such as the
seat of a chair, particularly an orthopedic chair, foot
supports such as arch supports, and other portions of shoes
and boots~ They may be used in ski boots wherein relative
rigidity in certain directions is desired in combination with
resilience in other directions of movement.
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