U.S. patent application number 13/570102 was filed with the patent office on 2012-11-29 for flush patch for elastomeric implant shell.
This patent application is currently assigned to ALLERGAN, INC.. Invention is credited to David J. Schuessler.
Application Number | 20120303120 13/570102 |
Document ID | / |
Family ID | 40756563 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120303120 |
Kind Code |
A1 |
Schuessler; David J. |
November 29, 2012 |
FLUSH PATCH FOR ELASTOMERIC IMPLANT SHELL
Abstract
An elastomeric prosthetic breast implant is provided having a
shell and a patch forming a flush interface with the shell and no
sudden surface steps on both interior and exterior surfaces of the
shell.
Inventors: |
Schuessler; David J.;
(Ventura, CA) |
Assignee: |
ALLERGAN, INC.
Irvine
CA
|
Family ID: |
40756563 |
Appl. No.: |
13/570102 |
Filed: |
August 8, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13288885 |
Nov 3, 2011 |
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13570102 |
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12431070 |
Apr 28, 2009 |
8070809 |
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13288885 |
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61038919 |
Apr 28, 2008 |
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Current U.S.
Class: |
623/8 ; 606/1;
606/191; 606/192 |
Current CPC
Class: |
A61F 5/0036 20130101;
A61F 2/12 20130101; A61F 5/003 20130101 |
Class at
Publication: |
623/8 ; 606/1;
606/192; 606/191 |
International
Class: |
A61M 29/00 20060101
A61M029/00; A61M 29/02 20060101 A61M029/02; A61F 2/12 20060101
A61F002/12; A61B 17/00 20060101 A61B017/00 |
Claims
1. A hollow medical implant, comprising: an elastomeric hollow
shell having a contiguous and consistent wall except in an access
region; and a patch extending across the access region of the shell
and securely bonded thereto, wherein a peripheral edge of the patch
and the shell cooperate to form a flush interface with no surface
steps on both interior and exterior surfaces of the implant;
wherein the patch is a substantially flat disk shape and the shell
wall covers and entire inner face of the patch and wherein the
patch increases in radial thickness for its periphery toward its
center such that the shell wall covering the inner face of the
patch is thickest adjacent the patch periphery; and the patch
including a self-sealing channel therein for the insertion of a
vent or fill tube.
2. The hollow medical implant of claim 1 wherein the implant is an
intragastric balloon.
3. The hollow medical implant of claim 1 wherein the implant is a
breast implant.
4. The hollow medical implant of claim 1 wherein the implant is a
tissue expander.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/288,885, filed Nov. 3, 2011, which is a
divisional of U.S. patent application Ser. No. 12/431,070, filed
Apr. 28, 2009, now issued as U.S. Pat. No. 8,070,809, which claims
the benefit of U.S. Provisional Patent Application No. 61/038,919,
filed on Apr. 28, 2008, the entire disclosures of which are
incorporated herein by this specific reference.
FIELD OF THE INVENTION
[0002] The present invention relates to patches for elastomeric
implants and, more particularly, to devices and methods for forming
a patch flush with an elastomeric implant shell.
BACKGROUND OF THE INVENTION
[0003] Implantable prostheses are commonly used to replace or
augment body tissue. In the case of breast cancer, it is sometimes
necessary to remove some or all of the mammary gland and
surrounding tissue that creates a void that can be filled with an
implantable prosthesis. The implant serves to support surrounding
tissue and to maintain the appearance of the body. The restoration
of the normal appearance of the body has an extremely beneficial
psychological effect on post-operative patients, eliminating much
of the shock and depression that often follows extensive surgical
procedures. Implantable prostheses are also used more generally for
restoring the normal appearance of soft tissue in various areas of
the body, such as the buttocks, chin, calf, etc.
[0004] Soft implantable prostheses typically include a relatively
thin and quite flexible envelope or shell made of vulcanized
(cured) silicone elastomer. The shell is filled either with a
silicone gel or with a normal saline solution. The filling of the
shell takes place before or after the shell is inserted through an
incision.
[0005] One process for forming flexible implant shells for
implantable prostheses and tissue expanders involves dipping a
suitably shaped mandrel into a silicone elastomer dispersion. The
outer silicone elastomer shell may have an anatomical
configuration, in this case matching the breast, and comes off the
mandrel with a shell hole. A patch over the shell hole typically
includes an uncured portion directly over the hole and a cured
portion covering that and adhered to the inner surface of the
shell. The patch is cured and then the hollow interior of the shell
is filled with an appropriate gel via a needle hole in the patch.
The needle hole in the patch is then sealed with a silicone
adhesive and the implant oven cured to achieve cross-linking of the
gel.
[0006] Another process for forming implant shells is rotational
molding, such as the system and methods described in U.S. Patent
No. 6,602,452 to Schuessler. The process also results in a flexible
implant shell having a hole that requires a patch.
[0007] Patches for flexible implant shells are sized larger than
the manufacturing hole to provide some bonding area. The overlap of
the patch on the shell results in a slight surface step on the
inside or outside of the shell which may be noticeable in the
finished product, which is undesirable. Also, such a palpable step
or discontinuity may irritate tissue in contact with the exterior
of the implant.
[0008] Despite many advances in the construction of soft prosthetic
implant shells, there remains a need for a smoother joint between a
patch and a manufacturing hole in the implant shell.
SUMMARY OF THE INVENTION
[0009] In accordance with the present invention, a hollow medical
implant comprises an elastomeric hollow shell having a contiguous
and consistent wall except in an access region, and a patch
extending thereacross. The patch is securely bonded to the shell
and a peripheral edge of the patch and the shell cooperate to form
a flush interface with no surface steps on both interior and
exterior surfaces of the implant.
[0010] In another aspect, the invention includes a hollow medical
implant, comprising an elastomeric hollow shell having a contiguous
and consistent wall except in an access region. A patch extends
across the access region of the shell and securely affixes thereto.
The patch has an outer flange and the shell wall forms an exterior
butt joint against a peripheral edge of the flange and overlaps an
inner surface of the flange in a manner that results in no surface
steps.
[0011] Both the elastomeric hollow shell and patch may be made of
materials with similar elastic modulus, durometer and elongation,
and may even be made of the same material. Desirably, the
elastomeric hollow shell is made of a solvent-based solid elastomer
and the patch is made of a liquid silicone rubber without a
solvent. In one embodiment, the patch includes a stem projecting
radially inward into the interior of the hollow shell and an outer
flange extending circumferentially outward from the stem, wherein
the shell wall forms a flush butt joint against a peripheral edge
of the flange and overlaps an inner surface of the flange and
extends at least to the stem. In another embodiment, the patch is a
substantially flat disk shape and the shell wall covers an entire
inner face of the patch. The patch flange may increase in radial
thickness from its periphery toward its center such that the
portion of the shell wall that overlaps the inner surface of the
flange is thickest adjacent the flange periphery.
[0012] In one form, the implant is for implantation in the breast
and the elastomeric hollow shell is accordingly shaped. Other
implant applications include for the buttocks, testes, calf, etc.
In some embodiments, the implant is a tillable implant, for
example, a saline tillable breast implant or tissue expander. In
other embodiments, the implant is an intragastric balloon.
[0013] In some embodiments, the implant is a tillable or inflatable
implant such as a saline fillable breast implant or an inflatable
intragastric balloon and the patch includes a fill valve for
facilitating inflation of the implant.
[0014] The present invention also embodies a method of formation of
a medical implant, comprising:
[0015] providing a mold cavity having a sprue orifice;
[0016] covering the sprue orifice with a patch;
[0017] introducing a silicone elastomer into the mold cavity;
[0018] causing the silicone elastomer to distribute generally
evenly around the mold cavity and over at least a portion of the
patch;
[0019] curing the silicone elastomer to form a hollow implant shell
having the patch bonded thereto; and
[0020] removing the implant shell from the mold cavity.
[0021] The patch may be shaped relative to and positioned within
the mold cavity so that after formation of the hollow implant shell
a peripheral edge of the patch and the shell cooperate to form a
flush interface with no sudden surface steps on both interior and
exterior surfaces of the implant. The step of introducing
preferably includes introducing the silicone elastomer into the
mold cavity through the patch. During the step of causing the
silicone elastomer to distribute generally evenly around the mold
cavity the method may include extending a vent tube through the
patch and venting gas from within the mold cavity though the vent
tube. Also, a tube may be inserted through the patch for filling
the mold cavity with a silicone gel through the tube, which is then
cured to form a solid prosthesis.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Features and advantages of the present invention will become
appreciated as the same become better understood with reference to
the specification, claims, and appended drawings wherein:
[0023] FIG. 1 is a plan view from above of a elastomeric implant
sealed by a patch construction in accordance with the prior
art;
[0024] FIG. 2 is a cross-section, to a slightly enlarged scale,
when viewed on section line 2-2 of the FIG. 1;
[0025] FIG. 3 shows, in cross-section, an alternative patch
construction in accordance with the prior art with a chamfered edge
of the aperture to be sealed by the patch;
[0026] FIG. 4 shows, in cross-section, an alternative patch
construction in accordance with the prior art;
[0027] FIG. 5 shows, in cross-section, a still further alternative
patch construction in accordance with the prior art;
[0028] FIG. 6 is a schematic cross-section of an exemplary
rotational molding system for use in forming the shell of a soft
prosthetic implant of the present invention;
[0029] FIGS. 7 and 8 are bottom and sectional views of one
embodiment of a mold for use in a rotational molding system such as
shown in FIG. 6 to form an elastomeric implant that receives a
flush patch of the present invention;
[0030] FIG. 9 is a cross-sectional view through an exemplary mold
of the present invention showing various elements of a process for
forming a flush patch;
[0031] FIG. 10 is a cross-sectional view through an exemplary
gel-filled breast implant prosthesis having a molded-in-place flush
patch formed in accordance with the present invention;
[0032] FIG. 11A is a detailed view of the interface between the
flush patch and the shell of the breast implant prosthesis of FIG.
10; and
[0033] FIG. 11B is a detailed view of the interface between an
alternative flush patch and the shell of the breast implant
prosthesis of FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] The present invention provides a gel-filled implant
prosthesis incorporating a shell composed partly or entirely of a
fluid barrier layer, preferably a silicone elastomer. The implant
shells of the present invention may have a single material layer of
homogeneous or uniform composition, or a laminated or layered
configuration. The primary application for gel-filled soft implants
is to reconstruct or augment the female breast. Other potential
applications are implants for the buttocks, testes, or calf, among
other areas. Moreover, though the present invention is particularly
advantageous for gel-filled implants, saline filled breast implants
or intragastric balloons may be modified to incorporate the
benefits herein. Further, tissue expanders which may not be viewed
as implants, per se, may also use the concepts disclosed herein.
For that matter, the term implant as used herein refers to long and
short-term implanted devices.
[0035] The implant shells of the present invention are desirably
formed using a rotational molding system, such as disclosed in U.S.
Pat. No. 6,602,452 to Schuessler, which is expressly incorporated
herein by reference. Schuessler discloses a rotational molding
machine for forming medical articles, in particular for molding
silicone elastomer shells for breast implants. Molding machines
other than those that rotate the mold, such as insert molding
machines in general (the insert being the patch), may conceivably
be used to mold in place the flush patch as described herein, and
the advantages of the present invention may even be incorporated
into traditional dip molding method, though modifications to the
typical dipping mandrel and rod are necessary and will not be
described herein.
[0036] The advantage of insert molding the patch in place within
the shell is that the patch integrates with the shell. That is, the
shell material flows over and around the patch and bonds tightly
thereto, if not actually melding together to blur any distinct
boundaries between the two items. How much of this integration
occurs depends on the similarity in the materials, and the mold
process parameters such as time and temperature. Preferably the
shell comprises a solvent-based solid elastomer (e.g., silicone)
and the patch is formed of a liquid silicone rubber (LSR) without a
solvent and with a similar elastic modulus, durometer and
elongation as the shell. Similar physical properties permits the
patch to deform and stretch with the shell which reduces stress
concentrators. Alternatively, the materials of the patch and shell
could be identical.
[0037] FIGS. 1 and 2 of the drawings illustrate a flexible implant
construction of the prior art. A breast prosthesis 21 comprises a
textured envelope or shell 22 formed by a conventional molding
process on a mandrel. A patch 23 covers an aperture in the shell 22
formed during the mold process. As best seen in FIG. 2, the patch
23 comprises an external overlay 24 and an internal underlay 25,
with respective overlapping portions 26, 27, so as to form a
sandwich structure. The overlapping sections of the patch 23 and
shell 22 as well as those portions of the overlay 24 and underlay
25 which are in contact are bonded together.
[0038] The patch can be bonded to the shell by a variety of means
including chemical welding or bonding, ultrasonic welding, and
heat/pressure fusing. One disadvantage of this process is that a
ridge 28 is formed on the exterior as well as a concentric ring 29
formed by the bonding process, part or all of which may be smooth,
i.e. where the textured exterior surface area of the shell 22 may
be reduced by the overlap of the overlay 24. This is undesirable,
because the exterior textured surface area ought to be maximized
for surgical reasons. Moreover, the circular ring 29 and peripheral
ridge 28 form a ridge on the breast prosthesis 21 that is
discernible by feel after implantation. The peripheral portion 27
of the underlay 25 also presents a small internal ridge which is
palpable after implantation. These physical discontinuities not
only present unnatural tactile sensations, but may result in
undesirable chafing between the prosthesis 21 and the breast
cavity.
[0039] FIG. 3 illustrates an implant shell 33 of the prior art
having a chamfered edge 32 around the mold aperture and opening
toward the interior of the shell. A patch member 34 bonded to the
interior of the shell 33 includes a conical portion which fits
closely against the chamfered edge 32 and a peripheral skirt 35
that abuts the interior of the shell 33. This construction
eliminates an external ridge, such as at 28 in FIG. 2, but the
peripheral skirt 35 still presents an interior ridge.
[0040] Alternatively, as shown in FIG. 4, a patch applied from the
interior of the shell 33 in FIG. 3 may comprise two parts, a cap
plug portion 34a, slightly larger than the aperture, and an
underlay portion 34b, larger still, such that when bonded together,
the whole patch extends radially around the aperture in the same
manner illustrated in FIG. 3.
[0041] The configurations shown in FIGS. 3 and 4 have the advantage
that a stronger bond is formed between the edge of the aperture and
the patch, since the edge area is increased by virtue of the
chamfer 32, when compared to a squared edge, and that no ridge is
formed on the exterior at the joint between the patch and the
shell. However, as mentioned above, an interior ridge remains. It
will be appreciated that the presence of any detectable seam
between the patch and the shell represents a stress point which
could possibly fail giving rise to leakage of fluid from the
prosthesis, which must be avoided.
[0042] Finally, FIG. 5 illustrates another patch configuration of
the prior art in which a prosthesis 40 includes a patch 42 closing
a mold aperture of a shell 44. The patch 42 comprises an external
surface 46 visible through the aperture, and an internal surface
48. The aperture has a chamfered mouth 52 to which a peripheral
extent of the external surface 46 conforms. The internal surface 48
extends outward from the mouth 52 in a skirt 54 that terminates at
a peripheral edge 56. This patch configuration once again presents
a smooth external surface to the prosthesis 40, with no ridge, and
is somewhat more streamlined than earlier versions, but the
internal peripheral edge 56 remains. Again, the edge 56 presents a
relatively sudden surface step and stress point around the patch 42
that is discernible from outside the patient after implantation. In
this context, a surface step is a relatively sudden surface change
such as an increase or decrease in thickness at the shell
wall/patch boundary.
[0043] FIG. 6 is a schematic of an embodiment of a rotational
molding system similar to that disclosed in Schuessler, U.S. Pat.
No. 6,602,452, which can be used to form implant shells of the
present invention. A two-piece case mold 120 affixes to a
multi-axis rotational mold machine 122 by clamps securing top mold
piece 124 and bottom mold piece 126 to clamp base 128 at top
locking groove 130 and bottom locking groove 132, respectively.
Vacuum connection 134 runs through one arm of the mold machine 122
to a vacuum opening 135. Material connection tube 136, through
which silicone elastomer, liner materials, and/or air are injected
into the mold cavity 140, may run through or along the same arm 142
as the vacuum connection 134 or by means of another arm 144. The
input fluid then continues through a circular sprue tube 145 fitted
in a circular opening (not numbered) of bottom mold piece 126. The
sprue tube 145 defines a hollow bore that allows materials to enter
an internal cavity of the two-piece case mold 120.
[0044] The hub 146 of the two arms rotates about axis A in the
horizontal direction, while the arms 142, 144 rotate about axis B,
which may be perpendicular to axis A. This allows a liner material
or silicone elastomer material to uniformly coat the surface of the
mold cavity 140. Two-piece case mold 120 may be manufactured from
copper, aluminum, or other materials. The top mold piece 124 and
bottom mold piece 126 fit together at their mating surfaces, seal
with an O-ring 150, and then lock into clamp base 128 of multi-axis
rotational molding machine 122.
[0045] Material reservoir 152 is fluidly coupled to connection tube
136 for providing silicone elastomer, liner material and/or air to
cavity 140. Vacuum source 154 and solvent condenser 156 are fluidly
coupled to vacuum connection 134. The hollow bore of the sprue tube
145 communicates with an inner vacuum tube (not shown) which in
turn is connected to vacuum opening 135 and vacuum connection
134.
[0046] The rotational molding system of FIG. 6 has two distinct
advantages over earlier methods for forming soft implant shells.
First, the system includes a vacuum vent to the mold via a rotating
arm of the equipment, which removes the solvent from silicones and
other solvent-based or gas-emitting materials. A second advantage
of the rotational molding system is that it enables the formation
of articles without seams at the mold parting lines by first
coating the inside of the mold with a thin layer of molding
material such as polyethylene, polypropylene, nylon, fluoropolymer,
polyester resin, polyurethane, epoxy or the like to create a mold
liner. After the liner is cast, then the raw material, e.g.
silicone elastomer, for the desired implant shell is injected into
the mold cavity and similarly rotationally cast inside the liner,
resulting in a temporary laminated construct. When the mold is
disassembled and the construct is removed from the mold, the liner
material and the implant are physically separated resulting in the
desired article having a seamless configuration.
[0047] FIGS. 7 and 8 illustrate an alternative mold 200 for a
rotational molding system, such as that described with reference to
FIG. 6, which can be used to form implant shells of the present
invention. As in the earlier embodiment, the mold 200 comprises a
top mold piece 202 and bottom mold piece 204 held together by bolts
206 across respective flanges 208. An inner liner 210 is
illustrated in cross-section in FIG. 8. Again, the presence of the
inner liner 210 is a significant advantage because the implant
shells may be formed without a seam that otherwise would result at
the intersection of the two mold pieces 202, 204. Desirably, the
mold pieces 202, 204 are formed of a metal such as aluminum, and
the inner liner 210 is formed of a non-adherent material such as
Teflon, for instance ETFE (ethylene-tetrafluoroethylene).
[0048] In contrast to the earlier-described embodiment, the inner
liner 210 is intended to be reused every time a prosthetic implant
shell is formed by the mold. The inner liner 210 remains within the
cavity formed by the mold pieces 202, 204, and thus defines the
inner surface of the mold 200, during the formation of a number of
implants. Preferably the inner liner 210 may remain within the mold
pieces 202, 204 for hundreds of uses. As with the earlier-described
embodiment, the inner liner 210 is initially formed by rotational
molding by injecting free-flowing liner material within the mold
pieces 202, 204. The mold 200 functions much like the
aforementioned two-piece case mold 120, in that it includes a
relatively large circular opening 212 within a lower flange 214
through or into which inserts a sprue tube (such as the sprue tube
145 of FIG. 6).
[0049] FIG. 9 schematically illustrates an alternative single-piece
mold 220 mounted on a rotational molding machine, such as described
above, in the process of forming a soft implant 240 comprising an
implant shell 244 having a molded-in patch 242, seen finished in
FIG. 10. A single-piece mold 220 obviously eliminates any seam
between mold parts, and thus a mold liner is unnecessary. After the
implant shell 244 with the molded in-patch 242 is formed, the mold
220 is disengaged from the rotational molding machine leaving the
patch visible through a mold neck 222. The resiliency of the
material used for the patch and the shell enables them to be folded
or otherwise compressed then removed from the mold neck 222.
[0050] The molding process involves introducing a silicone
dispersion within the mold cavity, rotating the mold 220, and
permitting a solvent within the silicone dispersion, such as xylene
gas, to be evacuated through a vent tube that extends centrally
through the patch 242. The silicone dispersion may be introduced
straight into the mold through the patch while holding the patch
242 in place, such as with a spring (not shown), or another channel
may be used for inserting the silicone. A mold plug contacts an
external surface of the patch 242 and seals within the mold neck
222. The vent tube passes through a bore in the mold plug, and from
there to a vacuum and solvent collection system.
[0051] FIG. 10 is a cross-sectional view through the exemplary
gel-filled breast implant prosthesis 240 comprising the shell 244
and molded-in-place patch 242. The prosthesis 240 may be filled
with a gel 246, such as silicone gel.
[0052] The patch 242 provides a reinforced access region on the
surface of the prosthesis 240 for passage of one or more implements
from the exterior to the interior. For instance, the mold process
described above desirably utilizes the patch 242 as a reinforced
conduit through which both the silicone dispersion tube inserts, as
well as the vent tube as shown in FIG. 9. Subsequent to the shell
molding process, a third tube may be inserted through the patch to
fill the interior of the shell with a silicone gel. And of course a
primary function of the patch 242, as detailed herein, is to enable
formation of a totally seamless implant with no surface steps
inside or out.
[0053] FIG. 11A is a detailed view of the interface between the
patch 242 and the shell 244. The patch 242 includes a stern 250
projecting directly radially into the interior of the shell 244 and
an outward flange 252 generally conforming to and forming a
continuation of the exterior shape of the shell 244. The material
of the shell 244 extends over the internal surface of the flange
252 at ring 260, extending at least to the stern 250, and
preferably continues in a tube 262 around the stern 250. Because
the patch flange 252 increases in radial thickness from its
periphery toward its center, the wall thickness of the ring 260
tapers thinner from the main part of the shell 244 to the tube 262,
and preferably has a uniform thickness along the stern 250. By
virtue of the implant material extending therearound, the patch 242
is securely held in place.
[0054] By introducing the patch 242 during the process of molding
the shell 244, rather than applying the patch to the shell aperture
afterwards, the patch integrates with the casting material flowing
over and around, thus producing a flush surface both inside and
out. In particular, an external surface of the prosthesis including
a circular interface line 270 at a flush butt joint between the
patch 242 and shell 244 has no ridges or other surface
irregularities. A butt joint means the juxtaposition of two edges,
in this case an inner-facing edge of the shell 244 and the
peripheral edge of the patch 242. The absence of surface
interruptions is a great advantage in reducing irritation to tissue
surrounding the implanted prosthesis, which has been traumatized
and is susceptible to inflammation. Likewise, an internal surface
of the prosthesis in the area of the patch 242 has no surface
irregularities, and in particular the boundary between the patch
242 and shell 244 is relocated to the radially inner end 272 of the
stem 250. Furthermore, molding the patch 242 into the shell 244
eliminates a secondary manufacturing step of adhering a patch to
the shell.
[0055] It is important to note that while prior implants utilized a
patch to cover an aperture left over as an artifact of the mold
process, the shell 244 actually has no such aperture. More
accurately, the shell 244 has a contiguous and consistent wall
except in an access region across which the patch 242 extends. That
is, the access region interrupts the generally constant thickness
shell wall. The patch 242 provides an access medium or port through
which tubes or other instruments may be inserted into the inner
cavity of the shell 244. In the access region, the material of the
shell thins to form the ring 260 over the internal surface of the
flange 252 and the tube 262 around the stem 250. Because the
material of the shell 244 does not cover the open top of the stem
250, an aperture through the shell technically exists, though not
the same type of aperture as previously seen with prior art shells.
Indeed, in an alternative version in FIG. 11B the shell may not
even have an aperture, and the patch in that case does not cover
anything but rather parallels, supports, or is juxtaposed against
the thinned access region to provide the access port. In this
sense, therefore, the term "patch" is sort of a misnomer, but will
be retained for the sake of familiarity.
[0056] The stem 250 of the patch 242 may be utilized to help
prevent clogging of tubes inserted into the cavity of the mold. For
example, as seen in FIG. 9, a vent tube extends through a channel
274 (FIG. 11A) in the patch 242 and extends into the mold cavity
through the inner end 272 of the stem 250. The silicone dispersion
that may at times aggregate near the patch 242 is prevented from
entering and potentially clogging the vent tube by virtue of
imposition of the upstanding stem 250. The channel 274 also
provides an avenue through which a gel-filling tube (not shown) may
be introduced after the shell 244 and patch 242 are molded
together. For instance, a gel, such as silicone gel 246 shown in
FIG. 10, may be injected through a tube inserted through the
channel 274. Therefore, the channel 274 may be used for introducing
silicone to the mold to form the shell, for venting the mold cavity
during the mold process, and/or for introducing the silicone gel
into the hollow prosthesis. Instead of providing a pre-formed
channel 274, the patch 242 may be made of a material or be
configured to be self-sealing. However, given the relatively large
bore tubes that may pass through the patch, a channel that is
subsequently sealed is more practical. A small well at the opening
of the channel 274 that helps guide the vent and gel fill tubes
into the channel may be filled with a silicone plug 276, such as a
silicone adhesive, to form a completely even outer prosthesis
surface.
[0057] FIG. 11B illustrates a portion of a soft implant prosthesis
240' that incorporates a low-profile flush patch 242'. The patch
242' includes an outwardly extending flange 252' but differs from
the above-described patch 242 by eliminating the radially extending
stem, and instead has a substantially flat disk shape. The patch
242' molds in place so that the surrounding shell 244' again meets
flush in a butt joint with the outward flange 252' to form a smooth
exterior surface interface 270'. The material of the shell 244'
also flows over the inner face of the patch 242' to form a cap 260'
that completely eliminates any internal boundary between the patch
and shell. The region 272' of the shell 244' adjacent and inward
with respect to the outer edge of the patch flange 252' is smooth,
and the thickness of the shell 244' at that point entirely covers
and cushions any potential tactile discontinuity presented by the
edge of the flange. There are certainly no sudden surface steps
inside and outside the patch periphery, as in the prior art. A
self-closing channel 274' through the patch 242' again provides
passage for insertion of a vent or gel fill tube, and a small plug
276' fills a small well at the outlet of the channel after
formation of the implant 240'.
[0058] It is contemplated by the inventors that a fill valve can be
provided in the patch for facilitating inflation and deflation of
the implant shell. For example, the implant may be an intragastric
balloon and the patch may include a valve useful for both inflating
and deflating the balloon. In other embodiments of the invention,
the implant may be a saline fillable breast implant or a tissue
expander and the patch may include a suitable valve for enabling
filling and or draining of the implant. All of these are considered
to fall within the scope of the present invention.
[0059] For breast implants, the formed shell is ready for further
assembly or processing consistent with the usual manner in creating
a final breast implant product. For example, the implant shell is
filled with a filler material of silicone gel or other
biocompatible gel material well known to those of skill in the art,
such as gel 246 shown in FIG. 10.
[0060] Although the invention has been described and illustrated
with a certain degree of particularity, it is understood that the
present disclosure has been made only by way of example, and that
numerous changes in the combination and arrangement of parts can be
resorted to by those skilled in the art without departing from the
scope of the invention, as hereinafter claimed.
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