U.S. patent application number 12/502654 was filed with the patent office on 2009-11-05 for two-layer external breast prosthesis with self-shaping feature and process for manufacture thereof.
Invention is credited to Roy Wade Bowman, Robert James Halley, Lisa Marie Hughey, Larry Dale Prosser, JR..
Application Number | 20090276043 12/502654 |
Document ID | / |
Family ID | 26765213 |
Filed Date | 2009-11-05 |
United States Patent
Application |
20090276043 |
Kind Code |
A1 |
Bowman; Roy Wade ; et
al. |
November 5, 2009 |
TWO-LAYER EXTERNAL BREAST PROSTHESIS WITH SELF-SHAPING FEATURE AND
PROCESS FOR MANUFACTURE THEREOF
Abstract
A two-layer external breast prosthesis comprising a first inner
layer comprised of a self-shaping dispersion and a second outer
layer comprised of an elastic material, wherein the second outer
layer is relatively stiffer than the first inner layer.
Inventors: |
Bowman; Roy Wade; (Cumming,
GA) ; Halley; Robert James; (Decatur, GA) ;
Hughey; Lisa Marie; (Marietta, GA) ; Prosser, JR.;
Larry Dale; (Douglasville, GA) |
Correspondence
Address: |
Ballard Spahr Andrews & Ingersoll, LLP
SUITE 1000, 999 PEACHTREE STREET
ATLANTA
GA
30309-3915
US
|
Family ID: |
26765213 |
Appl. No.: |
12/502654 |
Filed: |
July 14, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10081116 |
Feb 21, 2002 |
7575596 |
|
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12502654 |
|
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60270382 |
Feb 21, 2001 |
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Current U.S.
Class: |
623/7 |
Current CPC
Class: |
A61F 2002/526 20130101;
A61F 2/52 20130101; A61F 2002/503 20130101; A61F 2002/5032
20130101; A61F 2002/523 20130101 |
Class at
Publication: |
623/7 |
International
Class: |
A61F 2/52 20060101
A61F002/52 |
Claims
1. A two-layer external breast prosthesis, comprising: a) a first
inner layer comprised of a self-shaping dispersion, said dispersion
having a specific gravity of less than 1.0; and b) a second outer
layer comprised of an elastic material, wherein said second outer
layer is stiffer than said first inner layer.
2. The prosthesis of claim 1, wherein the elastic material of said
second outer layer comprises a silicon gel.
3. The prosthesis of claim 1, wherein the elastic material of said
second outer layer is heat cured.
4. The prosthesis of claim 1, wherein the self-shaping dispersion
of said first inner layer is uncured and comprised of a silicone
oil and a plurality of microspheres.
5. The prosthesis of claim 4, wherein the silicone oil has a
viscosity of approximately 500 CSt.
6. The prosthesis of claim 4, wherein the plurality of microspheres
are comprised of an acrylonitrile copolymer and have an average
particle size of from approximately 40 microns to approximately 125
microns.
7. The prosthesis of claim 1, further comprising a film wall
separating said inner layer and said outer layer.
8. The prosthesis of claim 1, wherein said inner layer is confined
within a first film envelope, and wherein said outer layer is
confined within a second film envelope.
9. The prosthesis of claim 8, wherein the said first and second
film envelopes share a common film wall therebetween.
10. The prosthesis of claim 8, wherein said first and said second
film envelopes each comprise a polyurethane film.
11. The prosthesis of claim 1, wherein said inner layer is confined
within a first film envelope and is sufficiently soft to yield to
the touch, and wherein said outer layer is sufficiently stiff to
substantially prevent wrinkling of a second film envelope confining
said outer layer.
12. The prosthesis of claim 1, wherein said outer layer is
sufficiently stiff to generally retain the shape of a human
breast.
13. A two-layer breast prosthesis, comprising: a) a first film
envelope configured to define a first interior volume; b) a second
film envelope joined to the first film envelope along a common side
edge to thereby define a second interior volume wherein said second
film envelope and first film envelope share a common film wall; c)
a first and a second sealed fill opening, respectively, extending
from the common side edge of the first film envelope and the second
film envelope to the respective first and second interior volumes;
d) a first material within said first film envelope forming an
interior body portion of the prosthesis, said first material
comprising a self-shaping material; and e) a second material within
said second film envelope forming an exterior body portion of the
prosthesis, said second material comprising an elastic
material.
14. The prosthesis of claim 13, wherein the self-shaping material
of d) is a self-shaping dispersion comprised of a silicone oil and
a plurality of microspheres.
15. The prosthesis of claim 13, wherein said self-shaping material
of d) is constructed and arranged to be yieldably shaped by a
patient's chest wall.
16. The prosthesis of claim 14, wherein the respective plurality of
microspheres have an average particle size of from 40 microns to
125 microns.
17. The prosthesis of claim 14, wherein said microspheres are
comprised of an acrylonitrile copolymer.
18. The prosthesis of claim 14, wherein said microspheres are
filled with isobutane.
19. The prosthesis of claim 13, wherein the first material of d)
has a specific gravity less than approximately 1.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of and claims
priority to co-pending U.S. patent application Ser. No. 10/081,116,
filed Feb. 21, 2002, which application claims priority to U.S.
Provisional Patent Application Ser. No. 60/270,382, filed Feb. 21,
2001. The aforementioned application(s) are hereby incorporated by
reference in their entirety for all purposes.
FIELD OF THE INVENTION
[0002] The invention relates generally to a breast prosthesis. More
particularly, the invention relates to a two-layer external breast
prosthesis having a first outer layer filled with a relatively firm
elastomeric material and an inner layer made of a flowable,
self-shaping material which is adapted to hold its shape against
the chest wall of a patient.
BACKGROUND OF THE INVENTION
[0003] A variety of breast prostheses are known. These devices have
been developed so that women who have undergone a surgical
procedure in which they have had one or possibly both breasts
removed, for example a mastectomy, may restore not only their
cosmetic appearance after surgery, but their self-confidence as
well. The use of breast prostheses has thus minimized the stigma
that may have otherwise been attached to a woman's appearance after
breast removal surgery.
[0004] One example of a prosthetic breast is disclosed in German
Patent No. DE-AS 26 05 148. This prosthesis has a shell shaped
component enclosed or enveloped by plastic films, and is made of a
two-component silicone rubber material. A cured two-component
silicone rubber material is used to form the shell of the
prosthesis, which material corresponds in its weight to the
approximate weight of natural breast tissue. The two-component
silicone rubber material also simulates the actual conditions of a
natural breast due to the soft, elastic responsiveness and mobility
of the material. Additional breast prostheses of this type, which
are intended for being placed in and supported by a brassiere, are
disclosed in U.S. Pat. Nos. 4,172,298 and 4,249,975,
respectively.
[0005] In order to assure the most natural appearance of the breast
prosthesis when inserted in the brassiere, a breast prostheses of
the type described above may be provided with a first body portion
forming the convex exterior side of the prosthesis, this portion
being made of a soft set material. In addition, a second and flat
shell shaped body portion forms the back or inner side of the
prosthesis, which second body portion is made of a slightly harder
set two-component silicone rubber material. The result of this
design is that the elastically soft material of the first body
portion, which due to its weight tends to sink slightly along the
convex external side thereof, is supported by the rear or flat
shell body portion made of the stiffer material. The disadvantage
of this type of prosthesis, however, is due to the fact that as the
inner shell is fabricated of a relatively harder or stiffer
two-component silicone rubber material, the inner shell will press
on the sensitive scar tissue area(s) of the patient's external
chest wall. Additionally, the inner shell also does not adjust,
i.e., it does not conform, about the scar tissue area(s) in order
to protect or cushion those tissues.
[0006] The problem persists in that many of the known types of
external breast prostheses have not been made adaptable to fit any
irregularities that may be present in the chest wall of the
mastectomy patient, particularly as modern surgical techniques
remove less tissue and leave more irregular chest wall contours.
Although matching a patient's chest wall contours has been
accomplished by the custom-molding of a prosthesis for each
patient, a need exists for a prosthesis that has desirable
appearance and touch characteristics, which can adapt to the chest
wall contours of a wide variety of women, and can also be made
available in a cost-effective manner.
[0007] One attempt to satisfy this need is disclosed in U.S. Pat.
No. 4,950,291 to Mulligan, the provisions of which are incorporated
herein by this reference. The '291 patent discloses a 2-layer
breast prosthesis comprised of an outer layer or shell filled with
a relatively firm elastomeric silicone gel, and an inner layer of
an extremely soft and flowable cross-linked silicone gel. The
softer, flowable gel will conform to the chest wall with a minimum
of applied force, but does not possess self-molding characteristics
such that, for example, the flowable gel does not hold its shape
when the prosthesis is removed. Also, due to the fact the inner gel
readily flows, the gel can "pool" at times in and along the bottom
of the prosthesis due to the influence of gravity, which in turn
may lead to patient discomfort and generally does not offer any
additional support to the fit and security of the prosthesis.
Furthermore, the soft gel-like material disclosed in the '291
patent is of the same density as the outer gel, and can therefore
result in a final product, which may be heavier than a comparable
single layer prosthesis.
[0008] What is needed, but seemingly unavailable in the art, is an
improved breast prosthesis that will have the desired outward
cosmetic appearance, shape, and feel of a woman's breast, yet will
be adaptable to the chest wall of the wearer by forming to the
profile thereof. What is also needed is such an improved breast
prosthesis which will be lighter than the known prosthetic devices
for greater patient comfort during prolonged wear, and which may
also be light enough that it will be self-supporting on the chest
wall of the wearer. Additionally, there is a need for an improved
two-layer breast prosthesis having a relatively firm outer shell
component with a relatively soft and compliant inner shell
component that will not settle as the prosthesis is worn by a
patient.
SUMMARY OF THE INVENTION
[0009] Among other aspects, this invention provides an improved and
lightweight breast prosthesis comprising two layers, each of which
is a shell shaped component. The breast prosthesis has an external
component or body portion which mimics the shape of the breast with
a hardness correlating to the soft, elastic responsiveness of
natural breast tissue, and has an inner component or body portion
comprised of a flowable, self-shaping material possessed with an
ability to hold its shape.
[0010] In contrast to popular belief that the frontal area of the
prosthesis must be supported by a rear shell-shaped component of a
greater hardness, the breast prosthesis of this invention
fabricates this rear component of a relatively softer material. The
inner shell shaped component thus is soft enough, due to its
consistency, that it is able to adjust to or fit about the scar
tissue area(s) of the patient's chest wall without exerting any
undue pressure thereon, and to maintain that shape/conformation in
the absence of internal shearing forces.
[0011] In a first aspect, the present invention provides a
two-layer external breast prosthesis comprising a first inner layer
comprised of a self-shaping dispersion, the dispersion having a
specific gravity of less than 1.0, a second outer layer comprised
of an elastic material, wherein the second outer layer is stiffer
than the first inner layer.
[0012] In a second aspect, the present invention provides a
two-layer breast prosthesis comprising a first film envelope
configured to define a first interior volume, and a second film
envelope joined to the first film envelope along a common side edge
to thereby define a second interior volume, wherein the second film
envelope and the first film envelope share a common film wall. A
first and a second sealed fill opening, respectively, extends from
the common side edge of the first film envelope and the second film
envelope to the respective first and second interior volumes. A
first material positioned within the first film envelope forms an
interior body portion of the prosthesis, the first material
comprising a self-shaping material. A second material is positioned
within the second film envelope for forming an exterior body
portion of the prosthesis. The second material comprises an elastic
material and/or curable elastic material precursor.
[0013] In still a third aspect, the present invention provides a
process for manufacturing a two-layer breast prosthesis comprising
the steps of providing a first film envelope configured to define a
first interior volume, and a second film envelope joined to the
first film envelope along a common side edge to thereby define a
second interior volume. The second film envelope and the first film
envelope share a common interstitial film wall, and both the first
and second film envelopes further comprise a respective first and a
second fill opening extending from the common side edge of the
respective first and second film envelopes to the respective first
and second interior volumes. The method also comprises at least
partially filling the second interior volume by passing an elastic
material and/or curable elastic material precursor through the
second fill opening; at least partially filling the first interior
volume by passing a self-shaping dispersion through the first fill
opening; and sealing the first and second fill openings.
[0014] Additional advantages and embodiments of the invention will
be obvious from the description, or may be learned by practice of
the invention. Further advantages of the invention will also be
realized and attained by means of the elements and combinations
particularly pointed out in the appended claims. Thus, it is to be
understood that both the foregoing general description and the
following detailed description are exemplary and explanatory of
certain embodiments of the invention and are not restrictive of the
invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a front or top plan view of a breast prosthesis
embodying the present invention, illustrating the first body
portion thereof.
[0016] FIG. 2 is a rear or bottom plan view, in partial
perspective, of the prosthesis of FIG. 1, illustrating the second
self-shaping body portion thereof.
[0017] FIG. 3 is a rear or bottom plan view, in partial
perspective, of the prosthesis of FIG. 1, illustrating an
impression made in and "held" by the self-shaping body portion
thereof.
[0018] FIG. 4 is a cross-sectional view of the prosthesis of FIG.
1, illustrating the first and second layers or body portions
thereof.
DETAILED DESCRIPTION
[0019] The present invention may be understood more readily by
reference to the following detailed description and any examples
provided herein. The terminology used herein is used only for the
purpose of describing particular embodiments of the present
invention and is not intended to be limiting in any way.
Furthermore, it must also be noted that, as used in the
specification and the appended claims, the singular form "a," "an,"
and "the" comprise plural referents unless the context clearly
indicates otherwise. For example, reference to a component in the
singular is intended to comprise a plurality of components.
[0020] Ranges may be expressed herein as from "about" or
"approximately" one particular value and/or to "about" or
"approximately" another particular value. When such a range is
expressed, another embodiment comprises from the one particular
value and/or to the other particular value. Similarly, when values
are expressed as approximations, by use of the antecedent "about"
or "approximately", it will be understood that the particular value
forms another embodiment. Moreover, it should be understood that
throughout this application, where publications are referenced, the
disclosures of these publications in their entireties are hereby
incorporated by reference into this application in order to more
fully describe the state of the art to which this invention
pertains.
[0021] As indicated above, in a first embodiment, the present
invention provides a two-layer external breast prosthesis
comprising a first inner layer comprised of a self-shaping
dispersion having a specific gravity of less than 1.0, and a second
outer layer comprised of an elastic material, wherein the second
outer layer is stiffer than the first inner layer. In accordance
with this and other embodiments disclosed herein, therefore, the
self-shaping dispersion of the first inner layer preferably
comprises a dispersion of silicone oil and a plurality of
microspheres formulated to provide the desired self-molding or
shaping characteristics. In one embodiment, the self-shaping
dispersion has a specific gravity of less than 1.0. In another
embodiment, the dispersion preferably has a reduced density of
0.4-0.5 (where water has a specific gravity of 1.0), compared to a
silicone gel containing no microspheres and having a specific
gravity of 1.0. Advantageously, the use of this self-shaping
dispersion is capable of providing the desired self-shaping
characteristics while reducing the overall weight of the
prosthesis.
[0022] In an alternate embodiment, it is contemplated that the
self-shaping dispersion will be comprised of non-crosslinked
material. As a result, the self-shaping material can advantageously
be redistributed within the breast prosthesis to accommodate
special considerations on the chest wall, such as mounds or voids.
Accordingly, the wearability characteristics of the breast
prosthesis are substantially improved, and despite the use of a
softer, flowable, and formable material and design of the inner
shell, the appearance of the breast prosthesis when inserted in the
brassiere does not suffer so that the prosthesis retains its
natural look.
[0023] To this end, in a preferred embodiment, the self-shaping
material will comprise a dispersion of microspheres suspended, or
dispersed, within a fluid media. It is anticipated that the fluid
media will comprise a silicone oil having a viscosity in the range
of from approximately 100 CSt to approximately 5000 CSt, including
such values as 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000,
3000, and 4000. In one embodiment, the silicone oil preferably has
a viscosity of approximately 500 CSt. To minimize the separation of
the dispersed components, i.e., the microspheres, optional
additives such as thixotropic agents and stabilizers may also be
added to the fluid/dispersion mixture. The fluid media acts as a
lubricant which allows the microspheres to shear and flow within
the inner layer of the prosthesis when it is received against the
patient's chest wall while being worn. After application, in the
absence of shearing forces, the weak mechanical interactions of the
microspheres create a weak structure which allows the material to
maintain its conformation, i.e., its shape. It should be understood
that since the self-shaping dispersion is an uncured dispersion, it
may separate over time, but can be regenerated by gently kneading
the backside of the inner layer of the prosthesis for a few
seconds.
[0024] In accordance with this and other embodiments that will be
described below, it should also be understood that the plurality of
microspheres can be comprised of a variety of polymeric substances
known to one of ordinary skill in the art, including without
limitation, such substances as glass or acrylonitrile copolymers.
Examples of available microspheres that may be used in the
self-shaping material include the Expancel 091-DE-50; 091-DET-50;
091-DE-80; 091-DET-80 (Akzo-Nobel) and Scotchlite microspheres
available from the 3M Company. In one embodiment, the microspheres
are preferably comprised of an acrylonitrile copolymer.
[0025] In yet another embodiment, it should also be understood that
suitable microspheres according to the invention will preferably
have an average particle size of between 40 and 125 microns,
including such values as 45, 50, 55, 60, 65, 70, 75, 80, 85, 90,
95, 100, 105, 110, 115, and 120 microns. To this end, it is
understood that the plurality of microspheres can be hollow and/or
gas filled. Such gases include, without limitation, organic gases
such as methane, ethane, propane, butane, isobutane and the like,
as well as inert gases such as nitrogen and the like. As such, in
an alternate embodiment of the present invention, at least a
portion of the plurality of microspheres are preferably filled with
an isobutane gas.
[0026] In view of the foregoing and in accordance with the present
invention, a typical formulation of the self-shaping material may
thus be comprised of a silicone oil (500 CSt) of 100 pbw, blended
with hollow microspheres of 4.5-5.5 pbw. Due to variances in
specific gravity and size gradients between microsphere batches,
one of ordinary skill in the art will appreciate that the actual
blend ratio may vary. The self-shaping dispersion is formulated so
that it stands on its own, with a consistency like whipped cream or
well beaten egg whites.
[0027] As previously indicated, in several alternate embodiments,
the self-shaping dispersion may be formulated with the addition of
one or more optional rheological additives and/or thixotropes. The
addition of the thixotrope increases the time required for the
components within the dispersion to separate, which improves
processing and therefore reduces the need for the end user to
frequently knead the product to re-disperse the components.
Non-limiting examples of suitable thixotropes can include Aerosil,
available from Degussa; Cab-o-sil, available from the Cabot
Corporation; and Wacker HDK, available from Wacker Silicones.
Therefore, a typical, non-limiting example in accordance with this
embodiment will comprise silicone oil (500 CSt) in the amount of
100 pbw; suitable microspheres in the amount of 2-4 pbw; and
Aerosil 200 in the amount of 1-4 pbw (thixotrope).
[0028] The second outer layer of the prosthesis is comprised of a
relatively stiff elastic material. To this end, the relatively
stiffer outer layer of the prosthesis maintains the shape of the
breast form and prevents outermost films from wrinkling while at
the same time remaining sufficiently soft to yield to the touch. In
a preferred embodiment, the elastic material is comprised of a heat
cured silicone gel. It is also understood that in an alternate
embodiment the outer layer silicone gel can likewise comprise a
material of reduced density, and hence a reduced weight through the
addition of microspheres.
[0029] It will be appreciated that the preparation of the
relatively stiff silicone gel based elastic material forming the
outer layer of the prosthesis is generally within the expertise of
those skilled in the art. An appropriate silicone rubber is
described in detail by Patzke and Wohlfarth in their article
entitled "Venetzungssysteme beim Siliconkautschuk," published in
the CHEMIKER-ZEITUNG 97.sup.th year (1973) No. 4, pages 176-180.
Furthermore, the relative stiffness of the silicone gel material
may be selected as desired to attain the advantages described
hereinabove. Preferably, the silicone rubber material forming the
outer layer will have a penetration measured in a range from 20.0
to 24.0 mm. Such values represent measurements with a "precision"
penetrometer using a 15 gram cone having an aluminum tip with a
height of 0.6 inches, a base diameter of 0.33 inches, and a plastic
cone body extending 1.13 inches from the tip base and having a base
diameter of 2.56 inches.
[0030] In accordance with this and other embodiments of the present
invention, the first inner layer and second outer layer of the
two-layer breast prosthesis are each confined within a first film
envelope and a second film envelope, respectively. In a preferred
embodiment, the first and the second film envelopes share a common,
interstitial film wall therebetween. Therefore, in one embodiment,
the inner and outer layers of the two-layer prosthesis are
separated by this interstitial film wall. To this end, any suitable
film composition known to one of ordinary skill in the art can be
used with the present invention. However, in a preferred
embodiment, the films used to form the respective film envelopes
are polyurethane films.
[0031] As previously set forth above, in a second aspect, the
present invention further provides a two-layer breast prosthesis
comprising a first film envelope configured to define a first
interior volume, and a second film envelope joined to the first
film envelope along a common side edge to thereby define a second
interior volume, wherein the second film envelope and the first
film envelope share a common film wall. A first and a second sealed
fill opening, respectively, which in each embodiment of the
invention may comprise a bifurcated fill valve or opening having
separate channels passing to each respective body portion of the
prosthesis, each extend from the common side edge of the first film
envelope and the second film envelope to the respective first and
second interior volumes. A first material is placed within the
first film envelope forming an interior body portion of the
prosthesis, the first material comprising a self-shaping material.
A second material is placed within the second film envelope to form
an exterior body portion of the prosthesis, the second material
comprising an elastic material and/or curable elastic material
precursor.
[0032] In a third aspect, the present invention provides a process
for manufacturing a two-layer breast prosthesis comprising the
steps of providing a first film envelope configured to define a
first interior volume and a second film envelope joined to the
first film envelope along a common side edge to thereby define a
second interior volume. The second film envelope and the first film
envelope share a common interstitial film wall, and the first and
the second film envelopes further comprise a respective first and a
second fill opening extending from the common side edge of the
respective first and second film envelopes to the respective first
and second interior volumes. The process further comprises at least
partially filling the second interior volume by passing an elastic
material and or curable elastic material precursor through the
second fill opening, at least partially filling the first interior
volume by passing a self-shaping dispersion through the first fill
opening, and thereafter sealing the first and second fill
openings.
[0033] Referring now to the drawings, in which like reference
characters indicate like parts throughout the several views, a
breast prosthesis 5 is illustrated. The breast prosthesis is made
of a first layer, envelope, chamber, or body portion 7 and a
separate second layer, envelope, chamber, or body portion 8. The
prosthesis can be manufactured by providing a first plastic film 9
and a second plastic film 12, which are used to form the film
envelopes of the prosthesis. A third film 11, an interstitial film
is sealably affixed by heat welding or any other means know to one
of ordinary skill, between the exterior films 9, 12 and along their
respective and common side edges to provide a first and a second
film envelope and leaving only a bifurcated fill opening 16 for
each respective envelope or chamber and extending from the common
side edge of the two film envelopes into the interior volume of the
envelopes so fabricated, and which envelopes will become the two
body portions of the prosthesis. In accordance with the embodiments
described herein, the films 9, 11, and 12 are preferably
polyurethane films.
[0034] The films are placed in a lower mold half (not illustrated)
of one of the known types of molds having a surface design similar
to the desired shape of a breast. A two-component soft set silicone
gel or other curable elastic material precursor 13 is passed
through one conduit of the bifurcated fill opening 16 in the welded
films 9 and 11 to thereby at least partially fill the interior
volume of the first film envelope, and to also form the convex
breast-shaped exterior first body portion of the prosthesis. A
self-shaping dispersion or material 15 is passed through a second
conduit of the bifurcated fill opening 16 between the films 11 and
12 to thereby at least partially fill the interior volume forming
the second layer or body portion of the prosthesis as well as the
concave interior side thereof. The aforementioned conduits of the
bifurcated fill opening 16, otherwise referred to as the first and
the second fill openings in the film envelopes, are then sealed
shut, simultaneously or individually, by heat welding or any other
means known to one of ordinary skill in the art. The mold is then
closed about the formed prosthesis by an upper mold component (not
illustrated) whose shape corresponds with the rear or back side of
the prosthesis, and heat is applied to the mold which causes the
film to form to the desired breast form shape, and cures the
silicone gel in the first or exterior body portion of the
prosthesis.
[0035] Therefore, in one embodiment, the present invention thus
provides a breast form having two chambers or shells 7,8 defined by
the three polyurethane films 9, 11, 12 joined together along and at
their outer peripheries, as illustrated in FIG. 4. The self-shaping
material 15 within the second chamber 8 closest to the patient's
chest wall is comprised of a dispersion of a silicone fluid and
expanded microspheres formulated to give the desired self-molding
characteristics. This dispersion has a reduced density of 0.4-0.5
(where water has a specific gravity of 1.0), compared to the
specific gravity of an unfilled (no microspheres added) silicone
gel of 1.0. The use of this material/dispersion therefore provides
the desired self-shaping characteristics while reducing the overall
weight of the prosthesis.
[0036] So formed, the self-shaping material 15 of the soft inner
dispersion can flow into cavities of the patient's chest wall when
being worn thereby in order to conform to the contours left in the
chest wall after surgery. The "feel" of the breast form is
realistic because the outer layer can move to the touch by
displacing some part of the soft inner silicone dispersion. The
stiffness of the outer gel layer 13 can be varied to the desired
parameters by controlling the composition curable elastic material
precursor, so that the thickness of the outer layer is decreased as
the stiffness thereof is increased. Therefore, the stiffness and
thickness of the gel layer 13 can be adjusted to produce the
desired "feel" of the prosthesis.
[0037] The self-shaping material 15 is preferably blended in a
double planetary mixer, a ribbon mixer, or similar mixer types and
under a vacuum to remove any dissolved air from the material. The
pumping of the material 15 into the second body portion, chamber or
envelope 8 of the breast prosthesis should be carried out with a
positive displacement pump in a closed configuration that does not
allow the material to be otherwise aerated.
[0038] Although several embodiments of the invention have been
disclosed in the foregoing specification, it is to be understood by
those skilled in the art that many modifications and other
embodiments of the invention will come to mind to which the
invention pertains, having the benefit of the teaching presented in
the foregoing description and associated drawings. It is thus
understood that the invention is not limited to the specific
embodiments disclosed hereinabove, but rather is intended to cover
such alternatives, modifications, and equivalents as may be
included within the spirit and scope of the invention as defined by
the appended claims. To this end, one skilled in the art will
appreciate that in practicing the present invention, only
reasonable and routine experimentation will be required to optimize
such variables and conditions as set forth herein.
* * * * *