U.S. patent number 3,663,973 [Application Number 05/098,816] was granted by the patent office on 1972-05-23 for cushion structure.
This patent grant is currently assigned to Stryker Corporation. Invention is credited to Wayman R. Spence.
United States Patent |
3,663,973 |
Spence |
May 23, 1972 |
CUSHION STRUCTURE
Abstract
A cushion structure constructed of a gel-like substance, such as
an organosiloxane gel comprising the reaction product of an
organosiloxane and a hydrogenosiloxane which is preferably a
copolymer of a particular combination of siloxanes combined with an
additive such as dimethylpolysiloxane. The gel is preferably
covered, at least on one side, by sheet material which may be
cloth, rubber, leather, foamed plastic or paper, depending upon the
particular use. A flexible mesh-like member, such as dacron net, is
preferably embedded within the cushion. The cushion structure is
used to at least minimize pressure necrosis.
Inventors: |
Spence; Wayman R. (Waco,
TX) |
Assignee: |
Stryker Corporation (Kalamazoo,
MI)
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Family
ID: |
22271039 |
Appl.
No.: |
05/098,816 |
Filed: |
December 16, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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621056 |
Mar 6, 1967 |
3548420 |
|
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515525 |
Dec 22, 1965 |
3308491 |
|
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Current U.S.
Class: |
528/15; 528/31;
623/37; 5/655.5; 5/909; 528/32 |
Current CPC
Class: |
A61G
7/05738 (20130101); A47C 27/14 (20130101); Y10S
5/909 (20130101) |
Current International
Class: |
A47C
27/14 (20060101); A61G 7/057 (20060101); A47c
027/08 (); A61f 005/04 () |
Field of
Search: |
;260/29.6B,91.3A ;3/20
;5/338,355,361 ;297/452,556 ;128/581,594,24,83 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gay; Bobby R.
Assistant Examiner: Calvert; Andrew M.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of my copending
application Ser. No. 621,056, filed Mar. 6, 1967 and entitled
"Cushion Structure," assigned U.S. Pat. No. 3,548,420, which in
turn was a continuation-in-part of application Ser. No. 515,525,
filed Dec. 22, 1965 and entitled "Cushion Structure," now U.S. Pat.
No. 3,308,491.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A cushion structure for protecting a mammal body against the
application on the body of injurious localized pressures,
comprising:
a cushion made of an elastic, nonfriable, nonporous, semisolid gel
of a synthetic organic material, said gel having a hydrostatic
property so that it is capable of easily flowing laterally under
pressure and is capable of returning toward its original shape as a
result of its internal restoring forces when the pressure is
removed:
said cushion having two substantially parallel major surfaces whose
dimensions are substantially larger than the dimensions of the
minor surfaces of said cushion, one of said major surfaces forming
a mammal-supporting surface so that when a mammal contacts the
mammal-supporting surface, the gel comprising the cushion will flow
laterally in order to avoid injurious concentrations of supporting
pressure in the area of support of said mammal by said cushion;
and
a thin, flexible and substantially flat sheet of porous mesh-like
material disposed within said cushion in substantially parallel
relation to said major surfaces whereby substantial quantities of
gel are disposed in layers on opposite sides of said sheet, said
sheet having sufficient porosity to permit the gel to penetrate
therethrough whereby the gel layers are integrally connected so as
to form a single mass of gel.
2. A cushion structure according to claim 1, including resiliently
flexible envelope means enclosing said cushion and closely engaging
same; and
a thin resiliently flexible and extensible casing loosely and
completely enclosing said envelope means and said cushion.
3. A cushion structure according to claim 1, in which the gel is a
reaction product of a methyl polysiloxane containing silicon-bonded
vinyl groups and a methyl polysiloxane containing SiH groups in
which said reaction is catalyzed by platinum.
4. A cushion structure according to claim 1, wherein said sheet of
material comprises a plastic, mesh-like fabric.
5. A cushion structure according to claim 4, wherein said sheet of
material comprises a dacron mesh.
6. A cushion structure according to claim 4, wherein said sheet of
fabric is disposed approximately midway between the major surfaces
and extends substantially coextensively with said major
surfaces.
7. A cushion structure according to claim 4, in which the cushion
consists essentially of an organosiloxane gel which is the reaction
product of an intimate mixture consisting essentially of (1) an
organosiloxane having a viscosity of from 100 to 10,000 cs. at
25.degree. C. and being a copolymer consisting essentially of units
of the formula RViSiO, R.sub.2 SiO and CH.sub.3 R.sub.2 SiO.sub..5
where each R individually is selected from the group consisting of
methyl and phenyl radicals and Vi represents a vinyl radical, at
least 0.174 molar percent of the units in said copolymer being the
said RViSiO units, (2) a liquid hydrogenosiloxane of the average
formula HRCH.sub.3 SiO (R.sub.2 SiO).sub.n SiCH.sub.3 RH where each
R is as above defined and n has an average value such that the
viscosity of the hydrogenosiloxane is no more than 10,000 cs. at
25.degree. C., no more than 25 molar percent of the total R
radicals present in (1)and (2) being phenyl: the proportions of (1)
and (2) being such that prior to reaction there is an average of
from 1.4 to 1.8 gram atoms of the silicon-bonded H atoms in (2) per
gram molecular weight of (1) and there being at least one RViSiO
unit in (1) for every silicon-bonded H atom in (2), the molecular
weight of (1) being calculated by the equation:
log visc. = 1.00 + 0.0123M.sup..5
where M is the molecular weight and "visc." is the viscosity of (1)
in cs. at 25.degree. C., and (3) a dimethyl polysiloxane fluid
having a viscosity of about 1,000 cs. at 25.degree. C. and
comprising from approximately 10 percent to 50 percent by weight of
said cushion.
8. A cushion structure according to claim 4, wherein said gel is
hypoallergenic, stable over a selected temperature range and
incapable of supporting the growth of bacteria.
9. A cushion structure for protecting a mammal body against the
application on the body of injurious localized pressures,
comprising:
a one-piece cushion made of an elastic, nonfriable, nonporous,
semisolid gel of a synthetic organic material, the gel having a
hydrostatic property so that it is capable of easily flowing
laterally under pressure and is capable of returning toward its
original shape as a result of its internal restoring force when the
pressure is removed;
a thin, flexible sheet of mesh-like fabric securely bonded to the
gel of said cushion, said sheet of fabric being substantially
coextensive with one of the external surfaces of said cushion,
whereby said sheet of mesh-like fabric resists damage to the gel
cushion due to forces applied to said cushion in a direction
substantially parallel with said fabric; and
flexible cover means surrounding and totally enclosing said cushion
and said sheet of fabric.
10. A cushion structure according to claim 9, wherein said sheet of
fabric is disposed totally within the gel cushion so as to form gel
layers on opposite sides of the sheet of mesh-like fabric with the
porosity of the mesh-like fabric permitting the gel layers to be
integrally interconnected so that the gel of the cushion is
effectively a single monolithic mass.
Description
FIELD OF THE INVENTION
This invention relates to a cushion structure and, in particular,
to an improved cushion structure usable in patient treatment for
protecting the body of a human or animal against localized
pressures.
BACKGROUND OF THE INVENTION
In the course of developing and adapting the cushion structure of
my U.S. Pat. No. 3,308,491 to various uses related to patient
therapy and treatment, I found that many problems were greatly
reduced, but not completely eliminated, by the original design of
the cushion structure, which was directed primarily, but not
entirely, to the relief of necrosis due to concentrations of weight
on pressure points produced by bones located close to the surface
of the skin. However, it is well known in the medical profession
that necrosis producing substantially the same discomforts can
results from pressures produced by prosthetic devices, by
corrective appliances and by plaster casts, especially if the
patient is ambulatory. Other similar and related conditions develop
the same type of pressure necrosis problems.
In addition to the foregoing, there are special weight-producing
pressure necrosis conditions, such as those encountered by people
having particular foot gear problems which require special
adaptation of my cushion structure. Almost all of these special
problems have certain common factors which, when understood, render
these problems capable of solution by variations in my cushion
structure. A principal factor was the need for maintaining the gel
in a relatively thin layer so that the cushion could fit into a
relatively narrow space and, further, confining the gel against
migration under conditions of substantially continuous and
relatively high pressure. Yet, on the other hand, where shearing
forces tend to develop due to shifting in the position of the
patient's body with respect to the pressure creating device, the
material confining the gel must be capable of allowing the gel to
effect the lateral movement which avoid the necrosis which usually
occurs with conventional pads for substantially the same purpose.
In other words, the containing material must be capable of holding
the gel in a selected position to minimize necrosis and soreness
due to excessive pressure without creating necrosis due to the
creation of prohibitive shearing forces parallel with the engaged
surface of the patient.
It was found that even small amounts of lateral movement provided
by the cushion could greatly reduce necrosis due to shearing forces
so that the gel could be used in combination with layers of fabric
or foamed plastic, for example, which would serve to contain the
gel within a selected, desired region.
Under some circumstances, particularly with ambulatory patients,
severe pressure conditions exist or occur on a periodic repetitive
basis. For example, particular problems may arise wherein the feet
may be sensitive in localized areas to the support of weight, such
as the metatarsal region, and are not sensitive when no weight is
placed upon such spots. Yet, due to the normal buildup of
protective calluses on the bottom of the foot, necrosis due to
shearing motions are not a problem. However, due to the excessive
weight concentrated on such sensitive spots, migration of the gel
becomes a far more serious problem. Thus, the containing material
must be capable of applying sufficient pressure in its uncompressed
condition (due to the weight of the human) to tend to move the gel
into a preselected position following each pressure application
produced by walking, for example. This type of problem also occurs
at the distal end of a stump where it is engaged by a prosthetic
device and in other similar circumstances.
During the further development of the cushion structure of my prior
U.S. Pat. No. 3,308,491, particularly when the structure was
provided in the form of a seat cushion, it was discovered that the
cushion was often moved from one place of use to another and, when
so moved, was mishandled and thereby damaged. That is, persons
without knowledge of the nature of the cushion would grasp it along
one edge and suspend it from such edge. Due to the substantial size
and weight of the cushion, support thereof in this manner sometimes
resulted in the breaking away of pieces of the gel core from the
remainder thereof.
Accordingly, it is a primary object of the present invention to
provide a cushion structure which overcomes the above-mentioned
disadvantages.
Particularly, it is an object of this invention to provide a
cushion structure for protecting the body of a human or animal
against localized pressures directed against the surface of the
body and usually capable of developing pressure necrosis of such
pressure concentrations are not eliminated.
A further object of this invention has been the provision of a
cushion structure, as aforesaid, which is hypoallergenic, stable
over a relatively wide temperature range, which will not support
the growth of algae and/or bacteria, which is relatively easy to
handle and maintain, which has good properties of moisture and
thermal resistance, and which includes a soft, nonfriable and
jelly-like material capable of absorbing relatively large shearing
forces without fracturing.
A further object of this invention has been the provision of a
cushion structure, as aforesaid, which can be used effectively in
zones where normal relatively thin padding has heretofore been used
while, at the same time, performing the aforesaid protection.
Still a further object of the present invention is the provision of
a cushion structure, as aforesaid, provided with a gel core having
a flexible mesh-like fabric disposed centrally within and
completely surrounded by the gel, the fabric being disposed
approximately midway between the upper and lower surfaces of the
core for providing the core with additional resistance against
damage while at the same time permitting the core to be effectively
formed as a single monolithic mass and without restricting
materially the capability of both sides of the gel core to absorb
pressures and minimize shearing forces.
Other objects and purposes of this invention will become apparent
to persons familiar with this type of structure upon reading the
following descriptive material and examining the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a cushion structure embodying the
invention.
FIG. 2 is an enlarged, broken, sectional view taken along the line
II--II in FIG. 1.
FIG. 3 is a plan view of a alternate cushion structure.
FIG. 4 is an enlarged, broken, sectional view taken along the line
IV--IV in FIG. 3.
FIG. 5 is an enlarged broken, sectional view similar to that
appearing in FIG. 4 and including protective cover sheets on the
opposite sides thereof.
FIG. 6 is a broken, cross-sectional view of the cushion structure
of FIG. 4 disposed between the outer surface of a human body and a
plaster cast.
FIG. 7 is a broken, partially sectioned view of another alternate
cushion structure.
FIG. 8 is a fragmentary sectional view taken along the line
VIII--VIII in FIG. 7.
FIG. 9 is a broken, partially sectioned view similar to FIG. 7 and
disclosing modified cushion structure.
For convenience in description, the terms "top," "bottom" and words
of similar import will have reference to the front and rear sides,
respectively, of the cushion structures appearing in FIGS. 1 and 3,
for example. The terms "inner," "outer" and derivatives thereof
will have reference to the geometric center of a said cushion
structure and parts thereof.
DETAILED DESCRIPTION
As shown in FIGS. 1 and 2, which illustrate one embodiment of the
invention, the cushion structure 11 is comprised of a relatively
flat and thin, self-contained, semisolid core 12 and a pair of
resiliently flexible sheets 13 and 14 disposed on opposite sides of
said core. Although the cushion structure 11 (FIG. 1) is shown as
being substantially rectangular in outside shape, it could be
otherwise if so desired. The core 12 is preferably made from an
organosiloxane gel, substantially of the type disclosed and
described in U.S. Pat. No. 3,020,260. Thus, said core will have a
soft, slightly tacky, nonfriable and jelly-like consistency in its
cured condition. Specific reference is made herein to the use of a
gel and, more specifically, to those gels known as organosiloxane
gels, because this particular material has been found especially
suited to the purposes of the invention. However, it may be found
that other gels and/or colloids, including jelly-like substances
which, strictly speaking, are not colloids, can serve
satisfactorily in carrying out the purposes of the invention.
The elastic, flexible sheets 13 and 14 may be fabricated from a
foamed material such as polyurethane or from any other elastic,
flexible material. Although such material should be of a type that
is reasonably soft and resilient, it should also to a certain
degree resist stretching. Sheets 13 and 14 may be secured together
wherever they are in contact with each other, as distinguished from
contact with core 12, by an adhesive material 16 such as, for
example, zinc oxide. As shown in FIG. 1, the zone of engagement
occurs along the entire periphery 14 of the cushion structure
10.
The particular embodiment of the cushion structure 11 described in
especially suitable for use with corrective appliances, such as a
Milwaukee Brace. In such an application the cushion 11 may be
disposed between the appliance and the patient's body in all areas
where pressure is apt to exist.
The laminated cushion structure 31 (FIGS. 3 and 4) is well adapted
for use between a patient and a plaster cast 43 (FIG. 6). Cushion
structure 31 has a central member 32 which is comprised of a porous
material, such as a sheet of foamed polyurethane or a fibrous
fabric, which is impregnated with a gel, such as the gel 12 in
cushion 11. The gel is applied to the central member 32 so as to
form layers 33 and 34 of gel disposed on either side of the central
member 32. In some cases, the gel which impregnates fabric and the
gel layers 33 and 34 are integral parts of a single mass in which
the fabric is embedded. Although the cushion structure 31 is
illustrated in a rectangular shape, it may be provided in various
shapes including long strips which, for example, may be rolled up
on a spool.
A pair of protective sheets 37 and 38 (FIG. 5) of material such as
paper may be provided adjacent the layers 33 and 34, respectively,
thereby preventing damage to or contamination of said layers during
handling. Immediately prior to use, the paper sheets 37 and 38 are
removed from the cushion structure 31. It is known that casts are
often located in regions where the adjacent surface 39 of the
patient's body can move excessively with respect to the cast in a
direction parallel with the surface 39. However, under normal
conditions, the cast will often be urged strongly against such
surface. The gel layers 33 and 34 may have a slightly tacky texture
which would normally cause them to stick to the surface 39 and the
cast 43, which would be undesirable in regions where said excessive
movement occurs. Thus, to provide for pressure protection and
excessive lateral movement, a layer of lubricant 42, such as talc,
is placed between the surface 39 of the patient and cushion
structure 31 before the plaster cast 43 is applied to the patient
over the cushion structure 31.
FIGS. 7 and 8 illustrate a further cushion structure 51 which is
specifically desirable when the cushions are of rather larger size
since the cushion structure possesses the necessary strength and
durability to permit ease of handling without fear of tearing or
otherwise damaging the gel core. The cushion 51 includes a core 52
which is formed from a gel, such as the gel 12 used in the cushion
11. The core 52 includes a thin central member 53 which comprises a
flexible, mesh-like sheet or fabric, such as a dacron mesh or net.
The mesh-like member 53 is disposed within the core 52 so that the
gel effectively forms layers 56 and 57 of gel disposed on opposite
sides of the fabric 53. However, due to the porosity of the member
53, the gel forming the core 52 effectively impregnates and totally
surrounds the member 53 so that the gel layers 56 and 57 are in
fact integrally bonded together and the layers 56 and 57 thus
effectively form a single monolithic mass of gel.
The cushion structure 51 is normally provided in the form of a seat
cushion having substantially parallel major surfaces 54 and 55, and
the mesh 53 is preferably disposed substantially midway between and
substantially parallel to the surfaces 54 and 55. Although the gel
of the core 52 is normally of such shape and strength that it is
capable of maintaining its own continuity, nevertheless the type of
use to which it is exposed generally dictates the use of some form
of container. For this purpose, the core 52 is preferably placed in
a resiliently flexible envelope 58 which may be made from a
stockinette material. The combined core 52 and envelope 58 are then
preferably inserted into a waterproof casing, such as a pure latex
rubber cover 59.
The provision of the intermediate fabric 53 impregnated and bonded
within the central portion of the core 52 is highly desirable since
it substantially strengthens the core 52 and thus reduces the
possibility of damage to the core 52 without restricting materially
the capability of the cushion 51 to absorb pressures and minimizing
shearing forces. Particularly, cushions of the type illustrated in
FIGS. 7 and 8, when used as a seat cushion, are generally of
substantial size and weight. Further, when the cushions are being
handled, there is a tendency to grasp the cushion by a corner
thereof, which can cause a piece of the gel to separate from the
remainder of the gel core. This type of damage is virtually
eliminated in the present invention since the fabric 53 provides
substantial strength to the overall cushion 51, particularly when
the cushion is being suspended vertically, as by being grasped
adjacent one edge thereof.
FIG. 9 illustrates a further cushion structure 61 which is similar
to the cushion structure illustrated in FIGS. 7 and 8.
Particularly, the cushion structure 61 is also provided in the form
of a seat cushion and includes a core 62 consisting of a gel which
may be of the same type used in the core 12. While the gel of core
62 is normally of such thickness that it is capable of maintaining
its own continuity, nevertheless the type of use to which the
cushion 61 is exposed also dictates the use of some form of
container. Thus, the core 62 is also preferably placed within a
resiliently flexible envelope 66, which may be of a stockinette
material, with the combined core 62 and envelope 66 then preferably
being inserted into a waterproof casing, such as a pure latex
rubber cover 67. The rubber cover 67 tends to strengthen the seat
cushion 61 and further reduce the possibility of damage to the gel
core 62 without restricting materially the capability of the pad to
absorb pressures and minimize the shearing force. The gel core 62
is also preferably provided with a thin, flexible, mesh-like sheet
or fabric 63 securely bonded to and impregnated with the gel of the
core 62. The fabric 63 is disposed adjacent one of the surfaces of
the core (the bottom surface in FIG. 9) so as to provide the core
with additional resistance against damage.
The gel portions or cores 12, 33, 34, 56, 57 and 62 are preferably
made from the reaction product of an intimate mixture consisting
essentially of (1) an organosiloxane having a viscosity of from 100
to 10,000 centistokes at 25.degree. C. and being a copolymer
consisting essentially of units of the formula RViSiO, R.sub.2 SiO
and CH.sub.3 R.sub.2 SiO.sub..5 where each R individually is
selected from the group consisting of methyl and phenyl radicals
and Vi represents a vinyl radical, at least 0.174 molar percent of
the units in said copolymer being the said RViSiO units, (2) a
liquid hydrogenosiloxane of the average general formula HRCH.sub.3
SiO (R.sub.2 SiO).sub.n SiCH.sub.3 RH where each R is as above
defined and n has an average value such that the viscosity of the
hydrogenosiloxane is no more than 10,000 cs. at 25.degree. C., no
more than 25 molar percent of the total R radicals present in (1)
and (2) being phenyl and (3) a platinum catalyst in an amount
sufficient to furnish at least 0.1 part per million of Pt based on
the combined weight of (1) and (2); the proportions of (1) and (2)
being such that prior to reaction there is an average of from 1.4
to 1.8 grams atoms of the silicon-bonded H atoms in (2) per gram
molecular weight of (1) and there being at least one RViSIO unit in
(1) for every silicon-bonded H atom in (2), the molecular weight of
(1) being calculated by the equation:
log visc. = 1.00 + 0.0123M.sup..5
where M is the molecular weight and "visc." is the viscosity of (1)
in cs. at 25.degree. C.
The above-described gel possesses very desirable hydrostatic
properties in that the gel is capable of easily flowing laterally
under pressure, the gel being capable of returning toward its
original shape as a result of its internal restoring force when the
external pressure is removed.
While the gel portions 12, 33, 34, 56, 57 and 62 may be made of a
pure reaction product as described in the preceding paragraph, it
may be found desirable in some cases to incorporate a quantity of a
filler or extender material in the reaction product in order to
minimize cost. It has been found satisfactory to use a filler
consisting essentially of dimethyl polysiloxane fluid which can be
uniformly mixed in the reaction mixture before the reaction begins.
The dimethyl polysiloxane fluid may be of viscosity of about 1,000
cs. at 25.degree. C. It has been found quite desirable to use about
25 percent by weight of the filler material, but approximately 10
percent up to 50 percent by weight can be used for some
applications.
Although a particular preferred embodiment of the invention has
been described above in detail for illustrative purposes, it will
be recognized that variations or modifications of such disclosure,
which lie within the scope of the appended claims, are fully
contemplated.
* * * * *