U.S. patent number 3,906,943 [Application Number 05/465,404] was granted by the patent office on 1975-09-23 for orthopedic device.
This patent grant is currently assigned to Yardney Company. Invention is credited to Elmer M. Arluck.
United States Patent |
3,906,943 |
Arluck |
September 23, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Orthopedic device
Abstract
An orthopedic device comprising a plastic sheet member having
one side covered with an insulating fabric layer which is
substantially thinner than said plastic sheet member. The plastic
sheet member has a tensile strength of at least 2,000 psi. The
orthopedic device preferably comprises a plastic sheet member
having one side covered with a thin insulating fabric and the other
side covered with a thin protective fabric. The orthopedic device
is formable at temperatures above 130.degree.F.
Inventors: |
Arluck; Elmer M. (New York,
NY) |
Assignee: |
Yardney Company (New York,
NY)
|
Family
ID: |
23847669 |
Appl.
No.: |
05/465,404 |
Filed: |
April 29, 1974 |
Current U.S.
Class: |
602/7; D24/190;
428/337; 442/288 |
Current CPC
Class: |
B32B
27/12 (20130101); A61L 15/07 (20130101); B32B
5/026 (20130101); A61F 5/0118 (20130101); B32B
7/12 (20130101); B32B 27/304 (20130101); B32B
5/26 (20130101); Y10T 428/266 (20150115); B32B
2262/0269 (20130101); Y10T 442/387 (20150401); B32B
2327/06 (20130101) |
Current International
Class: |
A61F
5/01 (20060101); A61L 15/00 (20060101); A61L
15/07 (20060101); A61F 005/04 () |
Field of
Search: |
;128/90,89,87
;161/88,89,227,257 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Yasko; J.
Attorney, Agent or Firm: Flynn & Frishauf
Claims
I claim:
1. A formable orthopedic device comprising a plastic sheet member
having one side covered with an insulating fabric layer which is
affixed to said plastic sheet member;
said plastic sheet member being at least about 50 mils thick, and
having a tensile strength at yield of between 2,000 and 10,000 psi,
an elongation at yield of between 3 and 30%, a flexural strength of
between 3,000 and 14,000 psi, a flexural modulus of between about
0.5 .times. 10.sup.5 and 7 .times. 10.sup.5 psi, a notched Izod of
between 0.3 and 30 foot pounds per inch, a Rockwell hardness of
between 15 on the R scale and 55 on the D scale, and a Vicat
softening point of between 60.degree. and 80.degree.C;
said insulating fabric layer being at least about 10 mils thick,
and is a fabric comprising fibers selected from the group
consisting of aramid fibers and high temperature cross-linked
phenolformaldehyde fibers, which has a coefficient of heat transfer
below about 2 cal/sec/cm.sup.2
/cm/.degree.C.times.10.sup..sup.-4.
2. The orthopedic device of claim 1, wherein said plastic sheet
member is between 50 and 120 mils thick and has the tensile
strength at yield of between 5,000 and 8,000 psi, an elongation at
yield of between about 4 and 8%, a flexural strength of between
about 8,000 and 12,000 psi, a flexural modulus of between about 2
.times. 10.sup.5 and 5 .times. 10.sup.5 psi, a notched Izod of
between 0.5 and 15 foot pounds per inch, and a Rockwell of between
90 and 100 R.
3. The orthopedic device of claim 2, wherein said insulating fabric
is between about 10 and 22 mils thick.
4. The orthopedic device of claim 3, wherein said plastic sheet
member is between about 65 and 80 mils thick, and wherein said
insulating fabric layer is a woven 50:50 blend of an aramid and a
high-temperature cross-linked phenolformaldehyde fiber.
5. The orthopedic device of claim 3, wherein said plastic sheet
member is an impact-modified polyvinyl chloride composition between
about 80 and 120 mils thick, and wherein said insulating fabric
layer is a woven 50:50 blend of an aramid and a high-temperature
cross-linked phenolformaldehyde fiber.
6. The orthopedic device of claim 1, wherein said plastic sheet
member is between about 65 and 80 mils thick, and wherein said
insulating fabric layer is a blend of an aramid and a
high-temperature cross-linked phenolformaldehyde fiber.
7. The orthopedic device of claim 1, wherein said plastic sheet
member is between about 80 and 120 mils thick, and wherein said
insulating fabric layer is a blend of an aramid and a
high-temperature cross-linked phenolformaldehyde fiber.
8. The orthopedic device of claim 1, wherein said device is heated
by application of heat to the side of the plastic sheet member not
covered with the insulating fabric layer and said plastic sheet
member is heated to temperatures of above about 160.degree.F, the
insulating fabric has insulating characteristics such that the
temperature of the outside surface of said insulating fabric layer
is at least 25.degree.F below the temperature of said plastic sheet
member.
9. An orthopedic device comprising a central plastic sheet member
having one side covered with a fabric insulating layer and the
other side covered with a fabric layer, both of 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 strength at yield of above 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 .times. 10.sup.5 and 7 .times. 10.sup.5 psi;
said insulating fabric layer being between about 10 and 22 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
130.degree.F.
10. The orthopedic device of claim 9, wherein said plastic sheet
member has a tensile strength at yield of between 2,000 and 10,000
psi, a notched Izod of between 0.3 and 30 foot pounds per inch, a
Rockwell hardness of between 15 on the R scale and 55 on the D
scale, and a Vicat softening point of between 60.degree. and
80.degree.C; and
said insulating fabric layer has a coefficient of heat transfer
below about 2 cal/sec/cm.sup.2
/cm/.degree.C.times.10.sup..sup.-4.
11. The orthopedic device of claim 10, wherein said plastic sheet
member has the tensile strength at yield of between 5,000 and 8,000
psi, an elongation at yield of between about 4 and 8%, a flexural
strength of between about 8,000 and 12,000 psi, a flexural modulus
of between about 2 .times. 10.sup.5 and 5 .times. 10.sup.5 psi, a
notched Izod of between 0.5 and 15 foot pounds per inch, and a
Rockwell of between 90 and 100 R; and
wherein said insulating fabric layer has a coefficient of heat
transfer below about 1.6 cal/sec/cm.sup.2
/cm/.degree.C.times.10.sup..sup.-4.
12. The orthopedic device of claim 11, wherein said other fabric
layer is a fabric selected from the group consisting of high
temperature stabilized nylons, high temperature stabilized
polyesters, and aramids.
13. The orthopedic device of claim 12 wherein when said device is
heated by application of heat to the side opposite that covered by
the insulating fabric layer and said plastic sheet member is heated
to temperatures above about 160.degree.F, the insulating fabric has
insulating characteristics such that the temperature of the outside
surface of said insulating fabric layer is at least 35.degree.F
below the temperature of said plastic sheet member.
14. The orthopedic device of claim 12 wherein said insulating
fabric layer is a fabric comprising fibers selected from the group
consisting of aramid fibers and high temperature cross-linked
phenol-formaldehyde fibers.
15. The orthopedic device of claim 10 wherein said device is heated
by application of heat to the side opposite that covered by the
insulating fabric layer and said plastic sheet member is heated to
temperatures above about 160.degree.F, the insulating fabric has
insulating characteristics such that the temperature of the outside
surface of said insulating fabric layer is at least 25.degree.F
below the temperature of said plastic sheet member.
16. An orthopedic device comprising a central plastic sheet member
having one side covered with an insulating fabric layer and the
other side covered with a high temperature knitted fabric
comprising fibers selected from stabilized nylon fibers and
stabilized polyester fibers, 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 strength at yield of between about 2,000 and
10,000 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 .times. 10.sup.5 and 7 .times.
10.sup.5 psi;
said insulating fabric layer being between about 10 and 22 mils
thick;
said knitted fabric layer being between about 4 and 22 mils thick
and functioning to protect said plastic sheet member; and
when said layer device is heated by the application of heat to the
knitted side and said plastic sheet member is heated to
temperatures above about 300.degree.F, said orthopedic device has
thermal characteristics such that it may be shaped and molded for a
period of at least about 41/2 minutes before it solidifies.
17. The orthopedic device of claim 16, wherein said plastic sheet
member is an impact-modified polyvinyl chloride composition and has
a tensile strength at yield of between 5,000 and 8,000 psi, an
elongation at yield of between about 4 and 8%, a flexural strength
of between about 8,000 and 12,000 psi, a flexural modulus of
between about 2 .times. 10.sup.5 and 5 .times. 10.sup.5 psi , and a
notched Izod of between 0.5 and 15 foot pounds per inch; and
wherein said insulating fabric layer has a coefficient of heat
transfer below about 1.6 cal/sec/cm.sup.2
/cm/.degree.C10.sup..sup.-4 ; and
wherein said orthopedic device has a shaping and molding time of at
least about 71/2 minutes.
18. The orthopedic device of claim 17, wherein said insulating
fabric layer is a woven 50:50 blend of an aramid and a high
temperature cross-linked phenol-formaldehyde fiber.
19. The orthopedic device of claim 18 wherein when said device is
heated by application of heat to the knitted side, the insulating
fabric has insulating characteristics such that the temperature of
the outside surface of said insulating fabric layer is at least
25.degree.F below the temperature of said plastic sheet member.
20. The orthopedic device of claim 18 wherein when said device is
heated by application of heat to the knitted side, the insulating
fabric has insulating characteristics such that the temperature of
the outside surface of said insulating fabric layer is at least
40.degree.F below the temperature of said plastic sheet member.
21. An orthopedic device formable at elevated temperatures
comprising a central plastic sheet member having one side covered
with a fabric insulating layer and the other side covered with a
stretch fabric which will not tend to distort the plastic sheet
member when said device is formed, said fabric 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 .times. 10.sup.5 and 7 .times. 10.sup.5 psi;
said insulating fabric layer being at least about 10 mils thick and
being substantially thinner than said plastic sheet member;
said stretch fabric layer being at least 4 mils thick and
functioning to protect said plastic sheet member.
22. The orthopedic device of claim 21, wherein said plastic sheet
member has a tensile strength at yield of between 2,000 and 10,000
psi, an elongation at yield of between about 3 and 30%, a notched
Izod of between 0.3 and 30 foot pounds per inch, and a Rockwell
hardness of between 15 on the R scale and 55 on the D scale.
23. The orthopedic device of claim 22, wherein said plastic sheet
member has the tensile strength at yield of between 5,000 and 8,000
psi, an elongation at yield of between about 4 and 8%, a flexural
strength of between about 8,000 and 12,000 psi, a flexural modulus
of between about 2 .times. 10.sup.5 and 5 .times. 10.sup.5 psi, a
notched Izod of between 0.5 and 15 foot pounds per inch, and a
Rockwell of between 90 and 100 R; and
wherein said insulating fabric layer has a coefficient of heat
transfer below about 2 cal/sec/cm.sup.2
/cm/.degree.C.times.10.sup..sup.-4.
24. The orthopedic device of claim 23 wherein said other fabric
layer is a fabric comprising fibers selected from the group
consisting of high temperature stabilized nylon fibers, and high
temperature stabilized polyester fibers.
25. The orthopedic device of claim 24 wherein said insulated fabric
comprises fibers selected from the group consisting of aramid
fibers and high temperature cross-linked phenol-formaldehyde
fibers.
26. The orthopedic device of claim 25 wherein said plastic sheet
member is a thermoplastic.
27. An orthopedic device shapeable at elevated temperatures
comprising a central plastic sheet member having one side covered
with a fabric insulating layer and the other side covered with a
knit fabric which will not tend to distort the plastic sheet member
when said device is shaped, said fabric 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, 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 .times. 10.sup.5 and 7 .times. 10.sup.5 psi; said
insulating fabric layer being at least about 10 mils thick and is a
fabric composed of fibers selected from the group consisting of
aramid fibers and high temperature cross-linked phenol-formaldehyde
fibers;
said stretch fabric layer being at least about 4 mils thick and
functioning to protect said plastic sheet member.
28. The orthopedic device of claim 27 wherein said stretch fabric
which will not tend to distort the plastic sheet member is a
knitted fabric comprising fibers selected from the group consisting
of stabilized nylon fibers and stabilized polyester fibers.
29. The orthopedic device of claim 28, wherein said plastic sheet
member has the tensile strength at yield of between 5,000 and 8,000
psi, an elongation at yield of between about 4 and 8% a flexural
strength of between about 8,000 and 12,000 psi, a flexural modulus
of between about 2 .times. 10.sup.5 and 5 .times. 10.sup.5 psi, a
notched Izod of between 0.5 and 15 foot pounds per inch, and a
Rockwell of between 90 and 100 R.
30. The orthopedic device of claim 29, wherein when said device is
heated by application of heat to the side of the plastic sheet
member not covered with the insulating fabric layer and said
plastic sheet member is heated to temperatures of above about
160.degree.F, the insulating fabric has insulating characteristics
such that the temperature of the outside surface of said insulating
fabric layer is at least 25.degree.F below the temperature of said
plastic sheet member.
31. An orthopedic device shapeable at elevated temperatures
comprising a central plastic sheet member having one side covered
with a fabric insulating layer and the other side covered with a
high temperature knitted fabric which will not tend to distort the
plastic sheet member when it is shaped, said fabric 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, 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 .times. 10.sup.5 and 7 .times. 10.sup.5 psi;
said insulating fabric layer being at least about 10 mils
thick;
said knitted fabric layer is a fabric composed of fibers selected
from the group consisting of stabilized nylon fibers and stabilized
polyester fibers and being at least about 4 mils thick and
functioning to protect said plastic sheet member; and
when said device is heated by the application of heat to the
knitted side and said plastic sheet member is heated to
temperatures above about 300.degree.F, said orthopedic device has
thermal properties such that it may be shaped and molded for a
period of at least about 41/2 minutes before it solidifies.
32. The orthopedic device of claim 31 wherein said plastic sheet
member has a tensile strength at yield of between 5,000 and 8,000
psi, an elongation at yield of between about 4 and 8%, a flexural
strength of between about 8,000 and 12,000 psi, a flexural modulus
of between about 2 .times. 10.sup.5 and 5 .times. 10.sup.5 psi, and
a notched Izod of between 0.5 and 15 foot pounds per inch.
33. The orthopedic device of claim 32 wherein said plastic sheet
member is an impact modified polyvinyl chloride plastic sheet
having a thickness between about 50 and 120 mils.
34. The orthopedic device of claim 33 wherein said insulating layer
is a fabric comprising fibers selected from the group consisting of
aramid fibers and high temperature cross-linked phenyl-formaldehyde
fibers.
35. The orthopedic device of claim 34 wherein said insulating
fabric layer is a blend of said aramid and said phenyl-formaldehyde
fibers.
Description
BACKGROUND OF THE INVENTION
This invention relates to orthopedic devices having broad medical
applications. These devices are used to support, position, protect,
immobilize and/or restrain portions of the body.
Orthopedic devices is a broad term that is used to described
medical structures such as casts, splints, supports, braces and
other means utilized to support, immobilize restrain, protect and
position body portions. They are used in many fields, including the
physical medicine and rehabilitation field, general medicine,
neurological field, and the veterinary field. They are also used to
prevent recurrance 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 usage. The
treatement 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 have had disadvantages inherent in some or all uses of
the material.
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 resiliant
support when that is required. The orthopedic device should be
capable of being formed in a practical manner and without
discomfort to the patient. Additionally, the orthopedic device
should not have properties which irritate the patient during the
period in which it is in service.
It is an object of this invention to provide an orthopedic device
having wide applicability and a unique combination of desirable
properties.
SUBJECT MATTER OF THE INVENTION
The orthopedic device of the present invention is a plastic sheet
member having at least one side covered with a thermally insulating
fabric layer. The plastic sheet member is between about 50 mils and
120 mils thick. The insulating fabric layer is between about 10
mils and 22 mils thick. It is capable of being molded (formed) with
application of normal finger pressure when the plastic is at a
temperature above 129.degree.-130.degree.F. When the device is
heated to substantially above 130.degree.F, e.g.,
165.degree.-350.degree.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 fabric is at least about 25.degree.F
cooler than the plastic member.
The orthopedic device preferably has both sides of the plastic
sheet member covered with fabric. The side covered with the
insulating fabric is the inside surface of the device and is the
side intended to be placed against the body surface during service.
The other side (the outside of the device) is covered with a fabric
layer (referred to herein as the "outside" or "other" fabric layer)
which protects the plastic. The insulating layer is bonded to the
plastic and preferably the outside fabric layer is bonded to the
plastic sheet member. The bonding is preferably accomplished by
bonding the plastic sheet member and the fabric layer with an
adhesive which may partially impregnate the fabric layer. The
outside fabric layer is between about 4 and 22 mils thick.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a rectangular blank having a construction in accordance
with 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 invention.
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 having a
construction in accordance with the embodiment of FIG. 2a.
The insulating layer of fabric is a woven, felted, matted, batted
or knitted fabric between about 10 mils and 22 mils thick. The
preferred insulating fabric is a woven blend, preferably 50:50, of
a high-temperature aromatic polyamide, now generically classified
as an aramid, and a high-temperature cross-linked
phenol-formaldehyde fiber such as the no-burn fabrics marketed by
Collins & Aikman Corp. which are blends of 50% Kynol and 50%
Nomex. Nomex is 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 U.S. Pat. No.
3,650,102. An aramid fabric may also be used.
The insulated fabrics may be used in weights of about 4 oz. per
square yard, up to about 16 oz. per square yard. The preferred
weight is about 5 to 8 oz. per square yard.
The insulating fabric preferably should have a coefficient of heat
transfer below about 2 cal/sec/cm.sup.2
/cm/.degree.Cx10.sup..sup.-4, and more preferably below about 1.6
cal/sec/cm.sup.2 /cm/.degree.Cx10.sup..sup.-4.
The insulating fabric layer is affixed to the central plastic
member with an adhesive, preferably a thermoplastic adhesive. Since
relatively high shaping and molding temperatures, e.g.,
400.degree.F, may be used to shape the orthopedic device, 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 200.degree.F and for an
added safety factor, it is preferred that it should retain said
property at above about 350.degree.F for devices which will be
shaped before service.
The outside adhesive may be a polyurethane; preferably a flexible
thermoplastic polyester type polyurethane adhesive. This material
also has the advantages of good resistance to perspiration, washing
and dry cleaning. Although the polyester type polyurethanes are
preferred, polyether types may also be used. Thermosetting
polyurethane adhesives may also be used, such as hydroxyl
terminated hexanediol adipate polyester cross linked with about 4%
of 4,4'-diphenyl methane diisocyanate.
An extruded polyester sheet about 21/2-3 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
350.degree.F 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 homopolymer and a copolymer of
ethylene and vinyl acetate. The adhesive may also be blends of the
foregoing.
The 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. The adhesive should not be a thick
foamed layer; it is preferably thin and not a foamed material.
The fabric, particularly when woven, may be partially or wholly
impregnated with a plastic adhesive before being applied to the
central plastic layer. The preferred insulating fabric layers are
partially impreganted, with the impregnating plastic being applied
from one surface to a depth of between about 0.1 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.
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 325.degree.F, 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 strength and flexural properties of the orthopedic device at
ambient temperatures are largely contributed by the plastic central
member. This member is strong and has the ability to be resilient
in some configurations and sizes. It has the ability to be
substantially rigid in specific configurations, i.e., O-sections,
L-sections, U-sections, etc. A device 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 illustrated by the
following properties of the plastic sheet. Different configurations
were prepared from sheet (90-93 mils thick) having the composition
illustrated hereinafter. The sheet was 63/8 inches long.
An O configuration was prepared with a radius of tube of
thirteen-sixteenths inches. The tube was held with clamps at each
end. The tube was supported at each end and on the bottom. The load
was supported on two focal points 4 inches apart at the bottom, and
the load applied from the top to the center of the tube. The
deflection follows:
Machine Deflection.sup.(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
______________________________________ .sup.(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 23/8 inches width of
configuration and a twenty-nine thirty-seconds 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 Deflection in (1 lb.) was Applied,
Measured Inches at Constant in Inches from Center of "U" Load
(logarithm) ______________________________________ 1.15 0.050 1.75
0.095 2.75 0.135 3.75 0.175 4.75 1.145
______________________________________
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" (logarithm)
______________________________________ 4.75 0.30 3.75 0.60 2.75
1.18 1.75 8.60 1.15 10.73
______________________________________
Two L-shaped configurations were prepared by holding 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 one-fourth inch radius
follows:
Points at which Constant Load Deflection in Inches (2 lbs.) was
Applied, Measured at Constant Load in Inches from Center of Bend
(logarithm) ______________________________________ 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 23/8
inches width of configuration and a twenty-nine thirty-seconds inch
radius follows:
Points at which Constant Deflec- tion (0.35 inches) was Obtained,
Load in Pounds at Measured in Inches from Center Constant
Deflection of Bend (logarithm)
______________________________________ 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 somewhat 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 of the plastic central layer.
The central plastic layer is usually between about 50 mils and
about 120 mils, although thicker layers may be utilized for large
sections, such as a major body cast where substantial rigidity is
required to support a large weight. Devices (in blank form, i.e.,
flat) used for preparing back supports, are preferably about 65-80
mils thick. Blanks for splints and braces are preferably about
80-120 mils thick. The preferred blanks for highly shaped casts may
be of a variety of widths dependent upon the final configuration
and service requirements.
The plastic preferably has a tensile strength (at yield) of between
2,000 and 10,000 psi and more preferably between 5,000 and 8,000
psi (ASTM D-638). The central plastic layer is relatively stiff as
reflected by a percent elongation at yield of between about 3 and
30% and preferably 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 .times. 10.sup. 5 and 7 .times. 10.sup. 5
psi and preferably between 2 .times. 10.sup.5 and 5 .times.
10.sup.5 psi. The notched Izod (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 60.degree.C and 80.degree.C.
A sample of the preferred impact modified polyvinyl 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). The 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 .times.
10.sup.3 psi and the Flexural Modulus is 4.1 .times. 10.sup.5 psi
(ASTM D-790).
Another sample of the same composition had a tensile strength at
yield of 6,785 psi; an elongation at yield of 5.6%; a flexural
modulus of 3.94 .times. 10.sup.5 psi; a flexural strength of 11,612
psi; a Rockwell R of 94; a Vicat of 74.degree.C; and a notched Izod
of 0.91 foot pounds per inch.
Another sample of the same composition which had been 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 .times. 10.sup.5 ; a flexural strength of
3,724 psi; a Rockwell R of 19; a Vicat of 63.degree.C; and a
notched Izod of 12.5 foot pounds per inch.
The central plastic member may be formulated from various polymer
systems, such vinyl-chloride-propylene copolymers,
vinyl-chloride-ethylene copolymers, or the corresponding
interpolymer containing diallyl maleate. It is preferred to utilize
an impact modified polyvinyl chloride (PVC) composition utilizing a
PVC resin having a number average molecular weight of
20,000-23,000. The composition contains between about 10 and 14
parts of an impact modifier, between 11/4 and 2 parts of lubricant,
and between 71/2 and 81/2 parts of a plasticizer, per 100 parts of
polyvinyl chloride homopolymer resin. The composition will also
contain stabilizers (6-9) parts and various processing aids
(1.5-2.1 parts) and usually pigments (up to 5 parts).
A preferred PVC composition and exemplified composition follow:
Preferred Preferred Range Composition COMPONENTS (parts) (parts)
______________________________________ PVC homopolymer resin
(20,000- 100 100 23,000) impact modifier (methylmeth- acrylate
butadiene-styrene 10-14 12.0 polymer processing aid (acrylic type)*
1.5-2.1 1.8 lubricant blend of olefinic monoglyceride and
hydrogenated olein 1-1.5 1.25 tri-stearyl citrate 0.25-0.35 0.3
plasticizer (di-2-ethylhexyl 7.5-8.5 8.0 phthalate) stabilizer
boosters epoxidized soybean oil 4-6 5.0 mixed di- and
tri-nonylphenyl 1.25-1.75 1.5 phosphite 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 TiO.sub.2 3.25 Hosterperm Red 0.0054 Indofast
Orange 0.0135 ______________________________________ *Rohm &
Haas K-120 N
A sheet of the polyvinyl chloride having a thickness of about 80-90
mils was prepared from small pellets about one-eighth .times.
three-sixteenth in diameter. The pellets were heated in an extruder
and the resin composition extruded in the form of a rope-shaped
material of a diameter of about one-half inch 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 producing them are disclosed in copending application,
Ser. No. 465,403 filed Apr. 29, 1974, entitled "POLYVINYL CHLORIDE
COMPOSITION" and naming AXEL W. TYBUS and LEONARD A. FABRIZIO as
the inventors. The disclosure of said compending application is
incorporated herein by reference.
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 procedure is to mill and calendar rope-shape material of
a diameter from about 1/2 to 4 inch. Sheet material taken from such
processes and particularly direct extrusion is stressed and is
preferably stress relieved by annealing at temperatures of about
320.degree.F. It is possible to anneal simultaneously with the
application of an adhesive or an adhesive and fabric.
The outside fabric 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. It also protects the plastic layer during heating. If a
heating element is used, for example, a hot iron, directly in
contact with the orthopedic support, the outside fabric layer
serves to prevent adherence of the plastic to the heating
element.
This outside fabric layer also functions together with the
insulating fabric layer to maintain the coherency of the orthopedic
device when it is heated to elevated temperatures. Since the
outside fabric layer is bonded to the plastic, it will be in
tension when the orthopedic device is shaped into a curve with the
outer fabric layer on the outside of the curve. It is therefore
preferably of a resiliant or stretch material which will not apply
pressure on and tend to distort the plastic layer at ambient and
particularly at elevated shaping and/or forming temperatures.
During heating, the outside fabric layer may be subjected to very
high temperatures. The preferred fabrics are those resistant to
prolonged heating at 250.degree.F and short term heating to
substantially higher temperatures. These high temperature resistant
fabrics include the high temperature stabilized nylons: the high
temperature stabilized polyesters; the Spandexs (polyurethanes);
the armids; such as Nomex; high temperature acrylics; the
aforedescribed Collins & Aikman blends of 50% Kynol and 50%
Nomex 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 elevated 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.
The other fabric layer is between about 4 and 22 mils thick and
preferably between about 10 and 15 mils thick. It is preferably
affixed to the plastic central member by an adhesive such as a
thermoplastic polyurethane resin.
The other fabric layer may be fixed to the central plastic member
by fusing with an adhesive in the same manner as that described
hereinbefore for affixing the insulating fabric layer to the
central plastic member. The same adhesive may be used in both
instances, or different adhesives particularly when the two fabric
layers comprise different types of fabric.
The orthopedic device may be made by sequentially affixing each of
the fabric layers to the central plastic layer. Orthopedic devices
have been prepared by first affixing a 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 21/2-3 mil thickness and the 7 oz. Collins & Aikman
fabric described hereinbefore through a Reliant roll press which
was at 350.degree.F 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 described hereinbefore, was
then affixed to the other side of the central plastic member by
passing the aforedescribed insulated fabric coated central plastic
member together with said fabric and an interposed 21/2-3 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 fabrics and the central plastic member
and the respective adhesive layers, which may be preapplied to the
fabric, through the roll press simultaneously to produce the
integral orthopedic device in a single pass. The blank orthopedic
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 orthopedic 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 extensive shaping and forming of the orthopedic device
such as forming a coil by wrapping various layers of the orthopedic
device about each other in a spiral, the temperatures may be
elevated, e.g., up to about 250.degree.-400.degree.F. At these
temperatures 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 fabric 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. The rough shaping is carried out as the
orthopedic device begins to cool from this elevated temperature.
When the outer surface of the insulating fiber is cooled
sufficiently, it may be pressed against the body portion to be
formed into its final shape, generally under finger pressure. After
the orthopedic 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 against 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 familar 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.degree.-500.degree.F, may be applied to the fabric layer 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 orthopedic 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.
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 contact, and the individual tolerance to
high temperature. For the purpose of applying orthopedic devices,
the temperature should not be above about 120.degree.-125.degree.F
for short term contact and preferably below 120.degree.F 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 temperature between about
165.degree.-185.degree.F 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.
The central plastic member of the orthopedic device solidifies at a
temperature of about 120.degree.-130.degree.F. As a consequence, it
is necessary that the temperature of the plastic central member
should be above about 130.degree.F during forming. Since
application of this temperature to the patient's skin for more than
a very short time is uncomfortable and possibly dangerous, the
outer temperture of the insulating fabric layer should be at least
25.degree.F cooler than the temperature of the plastic central
member during forming, and is preferably at least 30.degree.F
cooler. It is even more preferred that the outer temperature be at
least 350.degree.F or 40.degree.F cooler than the plastic. The
foregoing particularly applies during the plastic forming range of
130.degree.F up to about 160.degree.F.
In a preferred embodiment of the invention, the heat is applied
against the side of the orthopedic device covered by the other
fabric layer. For some service conditions it is contemplated that
both sides of the plastic central member may be covered by
insulating fabric. This would permit the entire member to be heated
to an elevated temperature and retain the heat for a longer period
of time.
The molded orthopedic device may be in many forms dependent upon
the intended service and particularly the portion of the body to
which 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. Rectangular and even oval or round blanks may be prepared.
These blanks will have the central plastic member in sheet form
with the insulating fabric bonded on one side and preferably the
other fabric 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 fabric coatings 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 rectangularshaped blank (flat
orthopedic device) 10 having the insulating fabric layer 11 on one
side of the plastic sheet.
FIGS. 2a and 2b illustrate two embodiments of the invention along
line 2--2 of FIG. 1.
FIG. 2a illustrates the 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
other fabric layer 13. The relative thickness of the layers in the
drawing is for illustrative purposes only.
FIG. 2b depicts the embodiment of the invention in which one side
of the plastic sheet 12 is not covered by a fabric layer. Such an
orthopedic device may be used by positioning the insulated fabric
side 11 against the body portion and then covering the exposed
plastic with a loose sheet material and applying a hot iron against
the sheet until the plastic is sufficiently soft so that it may be
molded to the desired body shape. It may also be preheated.
FIG. 3 illustrates a shaped and formed back support 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.
A flat blank orthopedic device was formed from a plastic sheet
member of a thickness of 91-93 mils and having the composition set
forth in the righthand column of the table hereinbefore was coated
on one side with the woven insulating fabric which is the
non-burning blend of 50% Nomex and 50% Nomax described
hereinbefore. This insulating fabric had a weight of about 7 ounces
per square yard and was about 14 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 325.degree.F and then covering the
plastic sheet and applying light pressure. The other side of the
plastic sheet was covered by a knit stabilized nylon fabric of a
thickness of about 14 mils similarly impregnated with the same
adhesive. It was similarly bonded to the plastic member.
The thermocooling characteristics of the various components of the
orthopedic device when heated to high temperatures, for example,
about 300.degree.F are illustrated in the following
time-temperature profile of a flat (blank) about 61/2 .times. 61/2
inches. 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) stabilized nylon 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.degree.-380.degree.F. The
adhesive was spread to a thickness of about 3 mils. The insulating
fabric was applied using the thermoplastic polyurethane adhesive
described hereinbefore. The nylon adhesive was the thermosetting
polyurethane described hereinbefore containing about 4% 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.degree.-71.degree.F) and measuring the rates thereof. The device
was positioned with the nylon fabric face about three-eighths of an
inch away from the hot plate and parallel thereto. The hot plate
was measured to have a surface temperature of about 409.degree.F.
The device was heated to the temperatures noted in the following
table and then permitted to cool. A thermocouple T.sub.3 was
positioned on the central plastic member face which is bonded to
the nylon, and a thermocouple T.sub.4 was on the side of the
plastic member which is bonded to the insulating fabric. The
time-temperature profile follows:
Time Temperature .degree.F (minutes) T.sub.4 T.sub.3
______________________________________ Heating 0 82 82 10 192 209
17 224 234 Heat Source Removed 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 3.0 206 213 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
______________________________________
Physical manipulation of the device established that the forming
period ended, i.e., the plastic had solidified when the plastic
temperature was about 130.degree.F. In some cases this appeard
closer to 129.degree.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.degree.F. Similar results were
obtained with other samples. 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. 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.
The aforesaid time-temperature profile establishes that there was
more than eight minutes of shaping and forming time, i.e., the time
starting with the removal of the heat source, until solidification
occurs. Pratical testing of numerous samples having the nylon
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 300.degree.F and preferably to 325.degree.F,
there is at least 71/2 minutes of shaping and forming time. Tests
with other experimental devices in which the other fabric is not
nylon, for example, cotton, have established that the cooling time
to solidification may be different and in some cases appreciably
shorter, for example, as little as 41/2 minutes.
The actual cooling time for a given 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 and the cooling
conditions.
Temperature determinations were also made on the outside of the
insulated fabric layer during the time-temperature profile, and
during other heating and cooling tests. It was found that when
using the aforesaid 7 oz. Collins & Aikman no-burn fabric, the
temperature differential between the outside of the fabric and the
plastic was about 40.degree.F. The temperature measurements
sometimes indicated a variation of .+-.10.degree.F, but were
usually within .+-.5.degree.F.
When the "blank" orthopedic device is severely shaped at
temperatures above about 325.degree.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 fabric 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 wish to
outline the shape, particularly when the shape is relatively
intricate, in a pattern on the blank (flat) orthopedic device
before cutting it into the rough shape and forming. This may be
accomplished in several methods depending upon the fabrics
involved. Certain fabrics, e.g., the woven blend of Kynol and Nomex
described hereinbefore, may be marked with a marker, e.g., pen,
pencil, crayon, etc. Alternately, a paper layer may be affixed to
one of the fabric layers by a pressure-sensitive adhesive. The
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
fabric layer.
The orthopedic devices of the present invention have many
advantages. When used as a relatively large support 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 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 position may be
desirable. In the past with plaster casts, the old cast had to be
removed and a new cast formed. The orthopedic devices of the
present invention may be partially reshaped even when attached to
the body by localized application of heat and molding.
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 without the foregoing adverse effects. This results from the
unique combination of physical properties which provide substantial
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.
The orthopedic devices may be used in the veterinary 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 applications it will be desirable
that the orthopedic device should be placed directly against the
body portion and encircle it, and therefore it is self attaching.
For other applications, the orthopedic device should have loops or
other means of attachment for belts and other types of bindings
such as Velcro fasteners, etc. These may be affixed to or even
incorporated 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 conform 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. They will also have the advantages over prior
orthopedic devices in their combination of rigidity and resilience
in different directions.
Although 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 connection with
orthopedic devices which will be attached to the body. They 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 resiliance in other directions of
movement.
* * * * *