Patent Publication Number: US-2013245758-A1

Title: Inflatable prostheses and methods of making same

Description:
INTRODUCTION 
     Related Applications 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/178,392, filed on Jul. 7, 2011, which is a continuation-in-part of U.S. patent application Ser. No. 13/105,715, filed on May 11, 2011, which is a continuation-in-part of U.S. patent application Ser. No. 13/021,523, filed on Feb. 4, 2011, which claims the benefit of U.S. Provisional Patent Application No. 61/301,910, filed on Feb. 5, 2010, and the benefit of U.S. Provisional Patent Application No. 61/409,440, filed on Nov. 2, 2010, the entire disclosure of each of these applications being incorporated herein in its entirely by this reference. 
    
    
     BACKGROUND INFORMATION 
     The present invention generally relates to medical implants and more specifically relates to inflatable prostheses, such as tissue expanders, suitable for implantation in a mammal. 
     Prostheses or implants for reconstruction and/or augmentation of the human body are well known. 
     Fluid filled prostheses, for example, mammary prostheses or breast implants, are widely used to replace excised tissue, for example after a radical mastectomy, or to augment the body to improve surface configurations. Although there are many applications where these are used, the most common is the mammary prosthesis, used to augment or otherwise change the size or shape of the female breast. 
     A conventional saline-filled breast implant includes an outer shell of several layers of silicone elastomer having a valve or fill port. The prosthesis is typically implanted into the breast cavity in an empty or only partially filled state. The implant is then inflated to its final size by means of the valve or fill port. This helps reduce the size of the needed incision, and enables a surgeon to adjust and even microadjust the volume of the implant. Unfortunately, the valve or fill port is sometimes noticeable to the touch. 
     Many or even most implants are manufactured to a given size and shape, and are implanted without means or expectation of changing their size after implantation or initial filling when first inserted into the breast. However, in many situations it is desirable to be able to adjust the size of the implant over a substantial period of time. If the volume can later be adjusted, an implant of lesser initial volume can be implanted, and as the post-surgical swelling goes down, the implant used as a prosthesis can be enlarged. Also, because often the procedure is for cosmetic purposes, it is useful to be able to make a later adjustment of size without having to replace the prosthesis with one of a different size, which would require a subsequent surgical procedure. 
     One problem with many conventional adjustable implants is that they require a valve to be part of the implant. It would be advantageous to provide an adjustable volume implant which does not require a valve or other access port for receiving fluid for adjustment. 
     Prior to implantation of a more permanent prosthesis, it is common practice to utilize a more temporary implant, for example, what is known as a “tissue expander” in order to gradually create the space necessary for the more permanent prosthesis. Keeping living tissues under tension by means of a tissue expander causes new cells to form and the amount of tissue to increase. Conventionally, a tissue expander comprises an inflatable body, having an inflation valve connected thereto. The valve may be formed into the inflatable body itself or may be remotely located and connected to the inflatable body by means of an elongated conduit. 
     The inflatable body of the tissue expander is placed subcutaneously in the patient, at the location of where tissue is to be expanded. The inflation valve, whether on the implant or remote thereto, is also subcutaneously positioned or implanted, and is configured to allow gradual introduction of fluid, typically saline, into the inflation body, by injection with a syringe. After gradual inflation at pre-determined intervals, the skin and subcutaneous tissues overlying the expander are consequently caused to expand in response to the pressure exerted upon such tissues by the inflatable body as solution is gradually introduced therein. 
     After gradual inflation at pre-determined intervals, which may extend over weeks or months, the skin and subcutaneous tissue will expand to the point where further medical procedures can be performed, such as the permanent implantation of a prosthesis, plastic and reconstructive surgery, or for use of the skin and subcutaneous tissue for use in some other part of the body. 
     During a mastectomy, a surgeon often removes skin as well as breast tissue, leaving the remaining chest tissues flat and tight. To create a breast-shaped space for a reconstructive implant, a tissue expander is sometimes used as described above. 
     In any event, it should be appreciated that locating the fill valve on a prosthesis such as a tissue expander or adjustable implant requires considerable practitioner skill. Attempts to make products which facilitate this include the development of various products having structure, for example, embedded magnets or a raised ring, for assisting physicians in locating the valve. 
     It has also proven difficult to develop a flexible protective material that is effective as a puncture resistant material while also being safe for implantation in the body. A puncture resistant material used as a component of a breast implant or tissue expander would ideally be sufficiently flexible such that the implant could still be folded or rolled and inserted through a small incision while also providing resistance to needle punctures aimed at inflating the implant/expander to its final size. 
     Bark et al., U.S. Pat. No. 5,066,303 discloses a self-sealing tissue expander with a shell having a flowable sealing material. According to Bark et al., fluid infusion into the shell can be done directly through the shell, without the need for a fluid entry port. 
     Schuessler, U.S. patent application Ser. No. 12/543,795, filed on Aug. 19, 2009, the entire disclosure of which is incorporated herein by this specific reference, discloses a fluid filled implant including a self-sealing shell. 
     There is a need for improved temporary tissue expanders, more permanent adjustable implants, and other inflatable prostheses. The present invention addressed this need. 
     SUMMARY 
     The invention relates to expandable prostheses, for example, implants and tissue expanders, and in particularly to implantable temporary tissue expanders as well as more permanent mammary prostheses. 
     Accordingly, the present invention provides implants, for example but not limited to tissue expanders and more permanent prostheses, for example, those implantable in a breast, and methods of making same. The present invention provides inflatable prosthetic implants, components thereof and methods of making same. In one aspect of the invention, inflatable prosthetic implants are provided which include, as a component of such implants, flexible, puncture resistant materials. 
     In another broad aspect of the invention, inflatable implants or prostheses, for example, tissue expanders and adjustable implants are provided which generally comprise a puncturable, self-sealing anterior portion, or shell, a puncture resistant posterior portion substantially opposing the anterior portion, and a fillable cavity defined between the anterior portion and the posterior portion. 
     It is to be appreciated that the terms “implant” “prosthesis” and “tissue expander” as used herein are intended to encompass permanent implants, including adjustable implants, as well as relatively temporary tissue expanders, and components, for example, shells, of such implantable devices. 
     In one aspect of the invention, a method of making an inflatable device or prosthesis, suitable for implantation in a mammal, is provided wherein the method generally comprises the steps of providing a plurality of mesh segments, positioning the plurality of segments on a curved molding surface, applying a fluid elastomeric material to the molding surface with the segments positioned thereon, and allowing the elastomeric material to set to form a flexible shell having an open end, the shell including the fabric segments embedded within the set elastomer, and the shell being useful as a component of an inflatable prosthesis. The step of positioning may substantially entirely covering the molding surface with the mesh segments, for example, in a manner such that the mesh segments overlap one another. The method further comprises the step of sealing the open end of the elastomeric shell, for example, by providing a puncture resistant member and sealing the puncture resistant member to the open end of the elastomeric shell. 
     In one embodiment, the mesh segments comprise a non-stretchable mesh fabric, for example, a substantially non-expanding polyester fabric mesh. In another embodiment, the mesh segments comprise a stretchable mesh fabric. 
     The method may further comprise the step of applying a tacky material to the curved molding surface prior to the step of positioning the mesh. The tacky material may be a fluid elastomeric material, for example, a silicone dispersion. 
     In another embodiment, the method comprises pre-shaping, for example, thermoforming, a mesh element, from a two-dimensional sheet into a three dimensional “sock” having the general shape of the molding surface. The method includes positioning the pre-shaped mesh element onto the molding surface, applying a fluid elastomeric material to the molding surface with the pre-formed mesh positioned thereon, and allowing the elastomeric material to set to form a flexible shell having an open end, the shell including the preformed mesh embedded within the set elastomer, and the shell being useful as a component of an inflatable prosthesis. 
     In another aspect of the invention, an inflatable prosthesis made by the methods described herein is provided. 
     Further, in another aspect, an inflatable prosthesis in accordance the invention generally comprises an interior shell defining an inflatable chamber, an exterior shell comprising a silicone-based elastomer material having a mesh embedded therein, a gel separating the interior shell and the exterior shell, and a puncture resistant member forming a base of the prosthesis. 
     In yet another aspect of the invention, a method of making a needle guard for an inflatable prosthesis suitable for implantation in a mammal is provided. The method generally comprises the steps of providing a first layer of puncture resistant members, for example, elongated slates, providing a second layer of puncture resistant members such that the second layer of members overlies and is offset from the first layer of members, molding or otherwise applying a flexible material to the first layer of members and the second layer of slats to form a device useful as a needle guard for an inflatable prosthesis. The step of applying or molding includes coupling the members to, for example, encasing the members within, the flexible material. 
     In one embodiment, the members are elongated slats, and the slats of the first layer are substantially parallel to the slats of the second layer. The slats may be made of any suitable puncture resistant material, for example, a material selected from the group of materials consisting of acetal, nylon, and polycarbonate. In some embodiments, the slats are made of a metal, for example, stainless steel, aluminum or titanium. The slats may be individual, separate elements that are cut from a sheet of material using any suitable means such as laser cutting. In other embodiments, at least one of the first layer of slats and the second layer of slats comprises a single sheet, undivided sheet of material having grooves defining the adjacent slats. 
     In some embodiments, the step of applying a flexible material comprises applying an elastomeric sheet between the first layer of slats and the second layer of slats, for example, applying an uncured elastomeric sheet between the first layer of slats and the second layer of slats, and subsequently curing the sheets. 
     Alternative to the first and second layers of slats, it is contemplated that a puncture-resistant fabric may be used, for example, in conjunction with an elastomeric layer, to form a suitable needle guard. 
     In one aspect of the invention, a method for making an inflatable prosthesis suitable for implantation in a mammal is provided, wherein the method comprises providing a needle guard made by a method of the invention as described elsewhere herein and securing a flexible, inflatable shell to the needle guard. 
     In another aspect of the invention, an inflatable prosthesis is provided generally comprising a flexible shell forming an anterior surface of the prosthesis, wherein the needle guard forms at least a portion of a posterior surface of the prosthesis, and comprises a elastomer portion and a first layer of puncture resistant slats embedded in the elastomer portion. The needle guard may further comprise a second layer of puncture resistant slats. In some embodiments, the second layer of slats is offset from the first layer of slats. 
     In yet another aspect of the invention, flexible, resilient puncture resistant assemblies are provided, the assemblies being, useful as components of surgical implants, for example, but not limited to, needle guards as components of inflatable implants that are accessed with a needle and syringe. Such implants for which the present materials are useful include inflatable tissue expanders. Other implants that can benefit from the present invention include fluid access ports which include a fluid reservoir and needle penetratable septum. In these and other implantable devices, puncture resistant or puncture proof assemblies of the invention can be highly beneficial, for example, as a means for preventing a needle tip from penetrating other areas of the device that are not intended to be punctured. Other beneficial uses for the present assemblies will become more apparent upon reading the present specification, and are considered to be included within the scope of the invention. 
     For example, puncture resistant assemblies are provided which are flexible and/or formable into desired configurations. 
     In some embodiments, puncture resistant assemblies are provided which are both flexible and resilient. Some of the present assemblies have the characteristic of shape memory, such that after being rolled or folded, they can resume an original shape or configuration. This aspect of the invention is particularly, but certainly not exclusively, useful for application in a surgical environment, in which the assembly may be in the form of a puncture proof material is rolled or folded into a narrow configuration, thereby enabling insertion thereof through a relatively small incision. Advantageously, some of the assemblies of the invention are structured to be able to automatically resume an original, pre-deformed shape, for example, automatically, once the material is at the desired implantation site. 
     In one embodiment of the invention, a puncture resistant assembly is provided which generally comprises a first composite guard, a second composite guard, and a intermediate layer securing the first and second composite guards together and/or containing the first and second composite guards. 
     Each of the first and second composite guards generally comprises an arrangement of puncture resistant elements or members, and a flexible substrate on which the members are secured and positioned, generally in a spaced-apart relationship. 
     The members may be in the form of domes or plates. The members have a hardness effective to resist penetration, puncture or breakage upon forceful contact with a sharp surface, for example, a tip of a needle, an edge of a cutting implement such as a scalpel or knife, or the like. The members may be made of any suitable material, such as a hard moldable substance, for example, a high durometer elastomer, polymer or rubber. Other suitable materials include metals, ceramics, and alloys thereof. 
     The flexible substrate on which the members are disposed may comprise a fabric, mesh, film, elastomer, or other material. 
     Notably, the first composite guard and the second composite guard are disposed with respect to one another such that the arrangement of members of the first composite guard is offset or misaligned with respect to the arrangement of members of the second composite guard. In some embodiments, a third composite guard is provided. The third composite guard may be positioned with respect to the first and second composite guards such that the members of the third composite guard are misaligned with the members of at least one of the first and second composite guards. 
     Advantageously, the misaligned or overlapping members of the adjacent composite guards provide a puncture resistant, or puncture proof, area while not significantly sacrificing flexibility of the assembly as a whole. That is, the composite guards may be arranged such that there are no significant gaps between individual puncture resistant members. It can be appreciated that depending upon the use of the final assembly, there may be some gaps between members so long as the gaps are sufficiently narrow to resist or prevent penetration by the type of instrument that the assembly is intended to be protected against puncture from. 
     In any event, in some embodiments of the invention, the puncture resistant members of the composite guards may provide a area of protection that substantially entirely covers a first side of the needle guard assembly. 
     The assembly may further comprise a intermediate layer, for example, an elastomer, securing together the first and second composite guards such that the members maintain their offset relationship. The intermediate layer may be located between adjacent composite guards and may be bonded thereto. In one embodiment, the intermediate layer seals the flexible composite members together and encapsulates the composite guards. For example, the intermediate layer may be an fluid tight barrier containing the two or more layered composite guards. In some embodiments, the intermediate layer exhibits a springiness and resiliency or provides a shape memory characteristic to the assembly. 
     In another aspect of the invention, a method of making a needle guard assembly is provided wherein the method generally comprises the steps of providing first and second composite guards where each composite guard includes a layer of puncture resistant members secured to a flexible substrate and bonding the first composite guard with the second composite guard in such that the members of the first composite guard are misaligned with the members of the second composite guard. In some embodiments, the method includes the step of bonding a third composite guard to the second composite guard such that the members of the third composite guard are misaligned with the members of at least one of the first composite guard and the second composite guard. 
     In some embodiments, the method may comprise the step of providing an intermediate layer between the composite guards. In some embodiments, the method may comprise the step of encasing or encapsulating the composite guards in a fluid tight seal. 
     In one embodiment, an inflatable prosthesis is provided which comprises an inflatable portion including an interior shell, an exterior shell comprising a silicone-based elastomer material having a mesh embedded therein and a gel separating the interior shell and the exterior shell. The prosthesis further comprises a needle guard assembly comprising a first composite guard and a second composite guard, each composite guard including an arrangement of puncture resistant members and a flexible substrate having a first side on which the puncture resistant members are disposed in a spaced apart fashion. The first composite guard and the second composite guard are positioned such that the arrangement of puncture resistant members of the second composite guard are misaligned with the arrangement of puncture resistant members of the first composite guard. The needle guard assembly further comprises an intermediate layer disposed between and connecting the first composite guard with the second composite guard. 
     In one aspect of the invention, the shell of the prosthesis comprises a self-sealing laminate defining an interior chamber of the prosthesis. The laminate generally includes a base layer formed from an elastomer, a layer of silicone of sufficient thickness for self-sealing of a needle hole there through and a top layer formed from an elastomer. The laminate may have a total thickness for enabling an internal chamber pressure of about 2.5 psi within an expander exterior compressor force of about 40 lbs. 
     More specifically, the laminate in accordance with this embodiment includes base and top layers formed from one type of silicone elastomer and an intermediate layer disposed between the base and top layers, formed of another type of silicone elastomer. For example, the base and top layers may be formed of Nusil PN-3606-1 and the intermediate layer may be formed of Nusil MED-6350. 
     In an exemplary embodiment, the base layer has a thickness of about 0.006 inches, the top layer has a thickness of about 0.006 inches, and the intermediate layer has a thickness of between about 0.100 inches and 0.120 inches. 
     An additional layer, for example, a polyester mesh layer, may also be provided as a part of the laminate to insure integrity of the tissue expander. 
     In another embodiment, described are shells for flexible, fillable prosthesis, the shells comprising: an inner shell; an outer shell; an intermediate layer between the inner shell and the outer shell; an assembly of composite guards disposed behind the inner shell; and at least one spacer configured to fill a space in the intermediate layer between the assembly of composite guards and the outer shell. 
     Also described are unfilled shells for a prosthesis, the shells comprising: an inner shell; an outer shell; an intermediate layer between the inner shell and the outer shell; an assembly of composite guards disposed behind the inner shell; and a fill ring attached to an inner surface of the inner shell configured to create an airspace for inflation of the inner shell with a gas. 
     Each and every feature described herein, and each and every combination of two or more of such features, is included within the scope of the present invention provided that the features included in such a combination are not mutually inconsistent. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be more clearly understood and certain aspects and advantages thereof better appreciated with reference to the following Detailed Description when considered with the accompanying Drawings of which: 
         FIG. 1  is cross-sectional view of a tissue expander in accordance with an embodiment of the invention, the tissue expander shown as implanted in a breast of a human being; 
         FIG. 2  is magnified view of a portion of the expander shown in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of another tissue expander in accordance with the invention; 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 3 ; 
         FIGS. 4A and 4B  are a simplified top view and cross sectional view, respectively, of a needle guard feature of the tissue expanders of the present invention; 
         FIG. 5  is a cross-sectional view of another tissue expander in accordance with the invention; 
         FIG. 6  is a cross-sectional view of yet another tissue expander in accordance with the invention; 
         FIG. 7  is a cross-sectional view taken along line  7 - 7  of  FIG. 6 ; 
         FIGS. 8-10  show steps useful in making some of the tissue expanders of the present invention; 
         FIG. 11  is cross-sectional view of another inflatable prosthesis of the invention including a puncture resistant assembly; 
         FIG. 12  is an exploded view of the prosthesis shown in  FIG. 11  in order to illustrate certain components of the puncture resistant assembly; 
         FIG. 13  is a top view of a composite guard which is a component of the puncture resistant assembly shown in  FIG. 11 ; 
         FIG. 14  is a magnified view of a portion of the composite encompassed by line  14  of  FIG. 13 ; 
         FIG. 15  is a cross-sectional view of the composite guard taken along line  15 - 15  of  FIG. 14 ; 
         FIG. 16  is a cross-sectional view, similar to the view shown in  FIG. 15 , of an alternative composite guard in accordance with certain aspects of the invention; 
         FIG. 16   a  is a cross-sectional view, similar to the view shown in  FIG. 15 , of yet another composite guard in accordance with certain aspects of the invention; 
         FIGS. 17-19  illustrate steps useful in making some of the puncture resistant assemblies of the present invention; 
         FIG. 20  is a cross sectional representation of a closed self-tissue expander shell comprising a laminate, in accordance with one embodiment of the present invention; 
         FIG. 21  is an enlarged cross sectional view taken along the line  21  of  FIG. 20  more clearly representing the configuration of the laminate of the shell shown in  FIG. 20 ; 
         FIG. 22  is a frequency/G′,G″ chart showing properties of a preferred material for an intermediate layer of laminate of the embodiment shown in  FIGS. 20 and 21 ; 
         FIG. 23  is a cross sectional view of another inflatable prosthesis of the invention including a puncture resistant assembly and a spacer;  FIG. 23A  is a magnified view of the spacer;  FIG. 23B  is a horizontal cross section of the inflatable prosthesis of  FIG. 23 ; and 
         FIG. 24  is a cross sectional view of a deflated prosthesis of the invention including a puncture resistant assembly, a spacer, and a fill ring;  FIG. 24A  is a magnified view of the fill ring. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention generally pertains to implantable inflatable devices and methods for making same, for example, devices such as soft fluid-filled implants, for example, but not limited to, permanent or temporary implants useful in breast reconstruction or breast augmentation procedures. 
     Turning now to  FIG. 1 , an inflatable device, in accordance with one embodiment of the invention, is shown generally at  10 , as implanted in a human breast  2 . The device  10  is being inflated with a suitable fluid, such as a saline solution  14 , by means of a typical syringe  18 . 
     The device  10  generally comprises an inflatable portion  12  comprising outer shell  22 , an inner shell  24  and a intermediate layer  26  there between. The inner shell  24  defines an inflatable cavity  28  (shown here as being filled with saline solution  14 ). 
     Inflation of the cavity  28  causes expansion of the device as shown by arrows  30 . The device  10  further includes a posterior portion  34  that is generally resistant to expansion upon inflation of cavity  28 . The total volume of the device  10  is adjustable by introduction and removal of fluid into and from the fillable cavity  28 . 
     The outer shell  22  of the device  10  may comprise at least one layer of elastomeric material, for example, a first layer  36  of elastomeric material and a second layer  38  of elastomeric material, and an additional layer of a different material, for example a reinforcement layer  40 , located between the first and second layers  36 ,  38  of elastomeric material. 
     The elastomeric material may be a silicone elastomer such as a dimethyl silicone elastomer, for example, a substantially homogeneous dimethyl-diphenyl silicone elastomer. One composition useful in the present invention is described in Schuessler, et al., U.S. application Ser. No. 12/179,340, filed Jul. 24, 2008, the disclosure of which is incorporated herein in its entirety by this specific reference. The elastomeric material may comprise a room temperature vulcanizing (RTV) or a high temperature vulcanizing (HTV) silicone from about 0.1-95 wt %, for example, about 1-40 wt %, for example, about 30 wt %. In an exemplary embodiment, the silicone-based fluid material is a high temperature vulcanizing (HTV) platinum-cured silicone dispersion in xylene. 
     The reinforcement layer  40  may comprise a mesh or fabric, for example, a synthetic polymer mesh or fabric, for example, a mesh or fabric made from poly(ethylene terephthalate) (PET), polypropylene (PP), polyurethane (PU), polyamide (Nylon), polyethylene (PE), any other suitable material, or combinations thereof. 
     In an exemplary embodiment, the outer shell  22  is made by dipping two or more layers of silicone-based elastomer over a conventional breast implant mandrel, followed by placement of a pre-fabricated 2 or 4-way stretchable “sock” of the said reinforcing material layer  40 , followed by two or more dips of the silicone-based elastomer. The reinforcing “sock” is able to take the shape of the mandrel and the fabric is trapped on both sides between the elastomer layers  36 ,  38 . In this embodiment, the stretchable pre-shaped “sock” (which may form the reinforcing layer  40  of outer shell  22 ) can be relatively easily mounted on the mandrel because of its flexibility and elasticity, making it easier to manufacture a reinforced shell with the intended shape and dimensions of the mandrel. The entire assembly forming the outer shell  22  is heated in an oven at a temperature and time suitable to cure the silicone. 
     In one embodiment of the invention, the reinforcement layer  40  is provided by forming a “sock” by using a cinch  40   a  as illustrated in  FIGS. 8 and 9 . Alternatively, the reinforcement layer  40  is thermoformed into “sock” by placing a single sheet of suitable material, for example a non-stretchable mesh, over a curved molding surface, for example, a mandrel, and gathering the mesh material at  40   b,  as shown in  FIG. 10 . The gathered mesh material is shaped, for example, thermoformed, to take on the 3-D shape of the mandrel. 
     Alternatively, rather than mesh sock, the reinforcement layer may comprise a plurality of fabric or mesh segments which are positioned on a mandrel or other curved molding surface. The segments may substantially entirely cover the molding surface. The segments may be positioned such that they overlap one another. The molding surface may first be contacted with a tacky material, for example, contacted with or coated with a silicone elastomer dispersion, to facilitate adherence of the segments thereto. An elastomeric material, such as an uncured silicone sheet or a silicone dispersion is applied to the molding surface with the segments positioned thereon. The elastomeric material is allowed to set to form a flexible shell having an open end, the shell including the fabric or mesh segments embedded within the set elastomer, and the shell being useful as a component of an inflatable prosthesis. 
     Post-curing, the reinforced shell is removed from the mandrel, and another elastomeric shell (which forms the inner shell  24 ) is placed inside the first shell (which forms the outer shell  22 ). The inner shell  24  may be a typical unreinforced elastomeric shell, or alternatively may be made similarly to that described above with respect to the outer shell  22 . The inner shell  24  may have the same or smaller size relative to outer shell  22 . The two shells  22 ,  24  are vulcanized close to their open base using, for example, a ring-shaped patch  44 , thus forming an inter-shell compartment. The dual-shell assembly is mounted back on a mandrel. The size of the mandrel can be the same as the one used for the inner shell fabrication or slightly larger. The latter would result in a laterally stressed inner shell with potentially enhanced sealing properties. 
     In some embodiments of the invention, at least one of the inner shell  24  and the outer shell  22  comprises an elastomeric material comprising a substantially homogenous layer of a silicone elastomer comprising a polysiloxane backbone and having a minimum mole percent of at least 10% of a substituted or pendant chemical group that sterically retards permeation of said silicone gel through the layer. More specifically, in this embodiment, the silicone elastomer is a polydimethyl siloxane and the pendant chemical group is one of a phenyl group, for example, a diphenyl group or a methyl-phenyl group, a trifluoropropyl group, and mixtures thereof. Such materials are described in detail in Schuessler, et al., U.S. patent application Ser. No. 12/179,340, filed on Jul. 24, 2008, the entire disclosure of which is incorporated herein by this specific reference. This material may make up one or more layers of the shell(s)  22 ,  24 . 
     After the inner shell  24  and outer shell  22  are bonded together, a cavity formed there between is then filled with a material, for example, a flowable material, for example, a silicone gel. This may be accomplished using any suitable means known to those of skill in the art. In one embodiment, the gel is introduced through a reinforced silicone plug  54  on the outer shell  22  ( FIG. 7 ). The silicone gel between the outer and inner shells  22 ,  24 , forms the intermediate layer  26 . After filling, the assembly made up of the inner shell  24 , outer shell  22  and intermediate layer  26 , is cured, for example, by exposing the assembly to heat in an oven for a suitable length of time. The mandrel that defines the desired shape of the implant can be round or oval, with a lower or upper pole for optimal projection. Before sealing the implant with a patch, a needle guard element, such as that described and shown elsewhere herein, may be inserted and bonded to the inner shell  22  and/or outer shell  24 , to form the posterior portion  34  of the device. 
     It can be appreciated that the device  10 , in the form of a tissue expander, once implanted in a patient, must be repeatedly accessed during the expansion process with percutaneous needle punctures, such as shown in  FIG. 1 . In some embodiments, the tissue expander devices are able to survive repeated puncturing and over-expansion to 200% by saline without leakage. 
     The device  10  can also be in the form of a more permanent mammary prosthesis, for example an adjustable breast implant. The volume of the implant can be adjusted in situ by accessing the cavity  28  with a needle through the self-sealing anterior portion of the device  10 . In some embodiments, the cavity  28  has a small volume relative to the gel portion  26 , to provide a comfortable implant having the desirable qualities of a gel-filled implant with the advantages of being size-adjustable with saline. 
     In summary, the anterior surface of the device  10  is self-sealing and can be accessed for fluid communication. The mechanism of self-sealing is facilitated by a combination of the gel layer  26  and shell  22 . After a void is created by a needle used to introduce filler (saline) into the implant  10 , the gel layer  26  prevents the saline  14  from having a direct path to the exterior and the reinforcing mesh  40  enhances this property by physically constraining the gel from expansion under pressure exerted by the saline  14 . The reinforcing materials  40  include but are not limited to meshes and fabrics made from PET, PP, PU, Nylon, etc. and combinations thereof. This invention features a novel manufacturing method for shaping the implant shell into 2-D and 3-D structures making it more convenient to manufacture and convert these reinforced structures into mammary prostheses. 
     In order to limit the depth of penetration of the needle, and also to give the medical professional feedback as to when the needle has reached the correct location for filling, conventional (prior art) tissue expander devices sometimes include a rigid backing or needle stop behind the filling port in the posterior side of the device. Typically these needle stops are made of metals or very hard or thick plastics to prevent needle penetration through the injection site. By nature then, these needle stops are quite rigid and inflexible, can be uncomfortable, and can limit the collapsibility of the device which affects ease of insertion of the expander through the initial incision. 
     In one aspect of the present invention, the posterior portion  34  of device  10  may comprise an improved needle guard  50 . The needle guard  50  may comprise any suitable biocompatible polymer (e.g. PE, PP, PU, PET, PI, TPU, high durometer silicones, ABS etc.) that is strong enough to resist needle puncture. The needle guard  50  may comprise one or more layers  56  of puncture resistant material with or without an intermediate layer  58 . In some embodiments, the needle guard  50  is structured so as to prevent, or substantially prevent, the device  10  from expanding toward the chest wall during inflation of cavity  28 . 
     For filling an implant of the present invention, syringe coupled to a 21 g or smaller needle may be used. The needle may be introduced anywhere in the anterior portion of the implant, such that it reaches the needle guard  50 , where it is prevented from penetrating further. The implant is then filled with saline or other liquids for tissue expansion. After removal of the needle, the assembly (e.g. outer shell  22 , inner shell  24  and intermediate layer  24 ) self-seals and prevents the implant from leaking. 
     In  FIGS. 3 and 4 , the needle guard  50  may comprise an elastomer portion  62 , and one or more layers of puncture resistant members coupled thereto. In the shown embodiment, members comprise elongated members, for example, slats  68  coupled to the elastomer portion  62 . 
     In this case, the needle guard  50  comprises one or more layers of slats  68 , for example, a first layer  64  of slats  68  and a second layer  66  of slats  68  coupled to the elastomer portion  62 . As shown, the slats  68  of the first layer  64  overlap, or are offset from, the slats  68  of the second layer  66 . For example, spacing between slats  68  of the first layer  64  are aligned with slats of the second layer and vice versa. Elastomer portion  62  may include grooves  69  or slots. Grooves may be aligned with slats  68  to facilitate rolling or folding of the device  10 . 
     Slats  68  extend across substantially the entire posterior portion  34  and are aligned substantially parallel to one another. This arrangement allows the device  10  to be rolled or folded in alignment with the slats  68  while the offset or overlapping positioning of the first and second layers  64 ,  66  provides protection in the event a needle enters spacing  70  between adjacent slats  68 . 
     Alternative to this arrangement, adjacent slats in each layer may overlap one another (not shown). The needle guard comprises overlapping but independent small pieces of rigid puncture-resistant material, and like the offset layers of slats  68  described and shown elsewhere herein, the overlapping configuration provide that there are no “line-of-sight” openings through which a needle can pass. 
     Slats  68  may be a polymer material. Slats may be, for example, nylon, acetal, polycarbonate, or other suitable, biocompatible, puncture resistant or puncture-proof polymeric material. Slats  68  may be metal, for example, stainless steel, aluminum or titanium. 
     In various exemplary embodiments, slats  68  may be between about    10   mm to about 100 mm or more in length, about 2 mm to about 30 mm in width, and about 0.2 mm to about 4 mm in thickness. Slats of other configurations and dimensions suitable for achieving the desired flexibility of the needle guard  50  may also be used. Such variations of materials and dimensions are considered to fall within the scope of the present invention. In one embodiment, slats  68  have a thickness of about 2 mm and the needle guard  50 , including first and second layers  64 ,  66  of slats  68  and elastomer material there between, has a total thickness of 5.0 mm or less. 
     Slats  68  may be formed by laser cutting same from a sheet of material. Alternatively, slats  68  may be defined by grooves in a single sheet of material. In this specific example, the 2 layers of parallel slats of puncture-resistant plastic about 0.25″ wide and with about 0.05″ open space between each slat. The layers are offset from each other so that the open space of one slat layer is centered on the middle of a slat in the layer below. All the slats are encapsulated in a soft flexible material like silicone. The open space between the slats gives the whole assembly flexibility to be readily folded or rolled up even though the plastic itself is rigid and resistant to extensive bending. Other shapes and layering designs of independent pieces of puncture resistant materials would provide the needle stop with more and different degrees of bending and folding capability. 
     The rigid or semi-rigid material forming the slats could be thermoplastics such as acetal, nylon, polycarbonate, and others; or thin metals such as stainless steels, aluminum, or titanium. The use of plastics can be advantageous in that the entire device  10  can be made to be MRI compatible. 
     In a similar aspect of the invention, thin elastomeric films (0.25 mm-1 mm) made of materials resistant to needle puncture may be used as a component of the needle guard portion of the implant. In some embodiments, such films can be provided with grooves in their design to allow folding/unfolding during insertion. The films may be attached to the shell using adhesives or alternatively may be are encapsulated in silicone. 
     In another embodiment, rather than independent slats  68 , one or more layers of flexible “slat sheets” are provided. In this embodiment, adjoining slats could be made by starting with readily available sheets of the desired plastic of the appropriate thickness. Parallel, adjacent slats are created by laser cutting through the plastic to create the desired spacing between slats but not all the way to the edges of the plastic sheet, thereby leaving a material, for example, a border that holds all the slats together. In this way the pre-cut slats can still be handled as one piece and therefore maintain the desired spacing and orientation. In one embodiment, two of these pre-cut plastic “slat sheets” are alternately layered between 3 sheets of silicone. After curing the silicone, a die cutter of the desired shape of the needle stop can cut within the borders of the pre-cut slats to stamp out the finished needle stop that now has many unconnected slats each independently encased in silicone. 
     Alternatively still, the pre-cut slat sheets could be held in the desired orientation in a mold and silicone could be injected and cured around them. Additional assembly steps could include creating a silicone border around the needle stop that would assemble to the expander envelope, texturing or adding features to the needle stop surface, or shaping the needle stop assembly so that it has a concave exterior to better fit the chest wall anatomy in the case of a breast tissue expander. 
     Turning to  FIGS. 4A and 4B , yet another variation of a needle guard  250  is provided, similar to needle guard  50 , except that rather than slats  68 , one or more layers of a puncture resistant mesh  152  are provided. Needle guard  150  may be substantially identical to needle guard  50  described above, with one or more differences being as follows. 
     In the shown exemplary embodiment, the needle guard  150  comprises one or more layers of mesh  152 , for example, a single layer of mesh  152  coupled to, for example embedded in, the elastomer portion  162 . In other embodiments, not shown, two or more layers of mesh are provided, wherein fibers or cords making up the mesh, in adjacent layers of mesh, overlap one another. For example, interstices or spacing between mesh fibers of a first layer of mesh aligns with the mesh fibers of a second layer of mesh, and vice versa. Alternatively, a single layer of mesh is provided with interstices between fibers being sized to prevent needle penetration there through. 
     Flexibility of mesh  152  and elastomer portion  162  allow the entire implant device to be rolled or folded upon insertion into a breast cavity through a small incision. 
     Mesh  152  may be a polymer or a metallic material. Mesh may be, for example, a polymer such as nylon, acetal, polycarbonate, or other suitable, biocompatible, puncture resistant or puncture-proof material. Mesh  152  may be metal, for example, stainless steel, aluminum or titanium. 
     It should be appreciated that in many of the embodiments of the present invention, the needle guard making up the posterior portion of the implant comprises puncture resistant members arranged in an overlapping configuration to provide no “line-of-sight” openings through which a needle can pass. These puncture resistant members can be variously configured and arranged to achieve this goal. 
     In a preferred embodiment, it is desirable for the needle stop to be flexible for insertion yet rigid to resist needle puncture. To prevent movement of the needle guard inside the device the needle stop material may be adhered, fused or vulcanized to the posterior of the implant or the patch. For this purpose, the needle guard may be dipped silicone that is then heat cured, such that the needle guard is covered by a silicone sheath. This silicone sheath is vulcanized to the silicone patch or posterior of the implant, to prevent movement of the guard inside the implant. 
     Another device  110  in accordance with the invention is shown in  FIG. 5-7 . Device  110  may be substantially identical to device  10  except that device  110  does not include an inner shell  24  or an intermediate layer  26 . Device  110  comprises a self-sealing outer layer  122 . Self-sealing outer layer  122  may be identical to layer  22  of device  10 . Further, rather than needle guard  50 , device  110  comprises needle guard  128  which comprises a puncture resistant elastomeric member  130  having grooves  132  for facilitating rolling or folding of device  110  during insertion. 
     Turning now to  FIGS. 11-16   a,  another device, for example, inflatable implant  310 , in accordance with the invention is shown generally. Implant  310  may be identical to implant  10  shown in  FIG. 3 , with the primary difference being that instead of needle guard  50  made up of layers of slats as described elsewhere herein, implant  310  includes a puncture resistant material  314  as shown and now described. 
     Device  310  includes a inflatable portion  312 , and a puncture resistant assembly  314 . 
     Device  310  is expanded or inflated (or deflated) by insertion of a needle  313  ( FIG. 1 ) through inflatable portion  312  (which may be identical to inflatable portion  12  of device  10 ) and introduction of fluid into a cavity  312   a.  Instead of inflatable portion  12 , it can be appreciated that inflatable portion  312  can include any suitable structure, including an elastomeric bladder having an access port with a needle penetratable septum, or may be made partially or entirely of a puncturable, but self sealing material. Some suitable self sealing materials are described, for example, in U.S. patent application Ser. No. 12/543,795, filed on Aug. 19, 2009, the entire specifications of which are incorporated herein by this reference. 
     In order to prevent the needle  313  from undesirably penetrating through the device  310 , the device is equipped with assembly  314 . 
     Referring now to  FIG. 12 , the assembly  314  generally comprises a first composite guard  316  and a second composite guard  318 . In the shown embodiment, the assembly  314  further includes a third composite guard  320 . In other embodiments, only two composite guards or more than three composite guards are provided. An intermediate layer  324  is provided between adjacent guards, for example, between guard  316  and guard  318 , and, likewise, between guard  318  and guard  320 . 
     Turning now as well to  FIGS. 13 and 14 , each of composite guards  316 ,  318 ,  320  includes a plurality of, for example, an arrangement, array, or pattern of, puncture resistant members  330 , and a flexible substrate  332  having a first side on which the puncture resistant members  330  are disposed in a generally spaced apart fashion. 
     As can be perhaps best appreciated from  FIG. 11  (and  FIG. 19 ), the first composite guard  316  and the second composite guard  318  are positioned such that the arrangement of puncture resistant members  330  of the second composite guard  318  are misaligned with the arrangement of puncture resistant members  330  of the first composite guard  316 . Similarly, the second composite guard  318  and the third composite guard  320  may be positioned such that the arrangement of puncture resistant members of the third composite guard  320  are misaligned with the arrangement of puncture resistant members of at least one of the first composite guard  316  and the second composite guard  318 . Thus, accordingly, the composite guards  316 ,  318 ,  320  are arranged relative to one another such that there are no straight line open spaces, or substantial gaps, between members  330  to allow a needle or sharp implement to penetrate entirely through the assembly  314 . Yet, advantageously, the assembly  314  as a whole may be quite flexible in that the substrate  332  on which the spaced apart  330  members are disposed is supple, flexible and/or bendable. 
     Turning specifically to  FIG. 12 , the intermediate layer  324  may comprise a flexible, connecting material which is effective to couple or bond the first composite guard  316  with the second composite guard  318 , and the second composite guard  318  with the third composite guard  320 . As shown in  FIG. 12 , the intermediate layer  324  is positioned between the arrangement of puncture resistant members  330  of the first layer  316  and the flexible substrate  332  of the second layer  318 , and another intermediate layer  324  is positioned between the arrangement of puncture resistant members  330  of the second layer  318  and the flexible substrate  332  of the third layer  320 . 
     The composite guards  316 ,  318 ,  320  may be identical to one another, and for the sake of simplicity, only the first composite guard  316  will now be described, with the understanding that, in the shown embodiment, what is described for the first composite guard  316  is also applicable to second composite guard  18  and third composite guard  320 . 
     The members  330  may be any suitable shape. In  FIG. 15 , the members  330  are somewhat dome shaped with rounded surfaces. In other embodiments, members  330   a  may be planar as illustrated in  FIG. 16 . Alternatively still, the members  330   b  may include both rounded surface and planar or flat surfaces, such as the members  330   b  which are dome shaped with a flat upper surface, as illustrated in  FIG. 16   a.    
     The members  330  have a thickness of between about 0.1 mm and about 1.0 mm, for example, a thickness of between about 0.2 mm and about 0.5 mm for example, between about 0.1 mm and about 1.0 mm. The members  330  have a spacing D of between about 0.2 mm and about 0.5 mm. The members  30  have a diameter of between about 0.5 mm and about 2.0 mm, for example, a diameter of about 1.5 mm. 
     In some embodiments, the guard  316  includes between about 50 and about 1000 members per square inch (psi), for example, about 400 psi. 
     In a specific embodiment, the guard  316  include about 400 members psi, each having a diameter of about 1.5 mm and each being spaced apart about 0.2 mm. 
     The members  330  (and  330   a  and  330   b ) are made of a suitable puncture resistant material, such as an epoxy, polymer, rubber, ceramic or metal, or suitable combination or alloy thereof. For some applications, suitable materials include polyethylene (PE), polypropylene (PP), polyurethane (PU), polyethylene terephthalate (PET), piolycarbonate (PC), polyisoprene (PI), thermoplastic urethanes and thermoplastic polyurethanes (TPU), high durometer silicones, acrylonitrile butadiene styrene (ABS) etc. In some embodiments, the members  330  are made of material selected from acetal, nylon, and polycarbonate. In some embodiments, the members  330  are made of a metal, for example, stainless steel, aluminum, titanium, or other metal. 
     The flexible substrate  332  may comprise a mesh, film, fabric, elastomer, or other suitable material. 
     The intermediate layer  324  may be a polymer, for example, an elastomeric polymer, for example, a silicone elastomer, for example, a low durometer silicone rubber. 
     In some embodiments, the assembly  314  has a resiliency or a shape memory such that it will restore from a folded or rolled configuration to an original, different configuration. The original configuration may be a generally flat or planar configuration. This may be provided by using a suitable intermediate layer material, such as a silicone elastomer that has a shape memory characteristic. 
     Assembly of the guard assembly  314  may be accomplished as follows and as shown in  FIGS. 17-19 . 
     Turning now to  FIG. 17 , guard  316  generally comprising members  330  and substrate  332 , is made by any suitable method, including stencil printing, for example, using equipment and processes used in surface mount technology/PCB fabrication. Other processes that can be used to make the guard  316  include micro-dot dispensing and printing, laser etching. Other suitable methods will be known to those of skill in the art. 
     Turning to  FIG. 18 , intermediate layer  324  may be formed as follows. A suitable material, for example, a sheet of uncured silicone, is placed on one side of the guard  316 , for example, on the side having members  30  and substrate  332 . The sheet is then subjected to curing conditions to cause the sheet to adhere to the members  330 , forming intermediate layer  324  thereon. In the presently described example embodiment, this step is done three times, with three separate guards  316 ,  318 ,  320 , to form the components  316 ′,  318 ′ and  320 ′ of assembly  314 . (See  FIG. 18   a ). 
     The assembly  314  is then placed in an oven or otherwise subjected to further curing conditions to seal the assembly components together such as shown in  FIG. 19 . 
       FIG. 20  shows an alternative shell  416  useful for forming a self sealing tissue expander or a more permanent prosthesis  410 , in accordance with the invention. Although not shown, it can be appreciated that the tissue expander/prosthesis  410  can include a needle guard  50 ,  128 ,  316 , forming a posterior surface of prosthesis  410 , as described elsewhere herein. 
     In this embodiment, the shell  416  comprises a laminate  420  made up of layered components, the laminate  420  being formable on a conventional mandrel, using conventional techniques. The shell defines a cavity which is fillable and expandable with a suitable fluid  420 . 
     With reference to  FIG. 21 , the laminate  420  includes an elastomer base layer  424 , a layer  428  of silicone, which is sufficient thickness for self-sealing of a needle hole there through (not shown), and a top layer  432  also formed from an elastomer. 
     The base and top layer  424 ,  432  may be formed of any suitable biocompatible elastomer. In a specific embodiment, layers  424  and  432  comprise any suitable silicone elastomer, for example, a silicone elastomer marketed under the name MED 6400, available from Nusil Technology, Carpinteria, Calif. (Shore A 30, ultimate tensile strength 1250 psi, % Elongation 900, tear strength 150 lbf/in.) 
     Preferably, the intermediate layer  428  is formed of a soft silicone gel having the viscoelastic properties (dynamic modulus G′,G″) of a product shown in the chart in  FIG. 22 , for example, a silicone elastomer marketed under the name MED 6350, also available from NuSil. This preferred material has dynamic modulus G′, G″ between Nusil MED  6400  and a cohesive silicone gel. In this chart, G′ represents storage modulus of material indicative of shape/dimensional stability, and G″ is loss modulus of material indicative of flow within material. 
     The intermediate layer preferably comprises a material with storage modulus at about 0.1, 1 and 10 Hz of about 4490, about 8330 and about 18800 Pa, respectively. Further the material may have a loss modulus at 0.1, 1 and 10 Hz of about 1840, about 4820 and about 12400 Pa, respectively, and a complex viscosity at 0.1, 1 and 10 Hz of about 7720, about 1520 and about 358 Pa·s. For example, the intermediate layer may be Nusil MED 6350. 
     It has been found that when the base layer  24  has a thickness of about 0.006 inches and a silicone layer  28  has a thickness of between about 0.100 inches and 0.120 inches, and the top layer has a thickness of about 0.006 inches. An internal chamber pressure of about 2.5 psi can be established with expander exterior compressor force of about 40 lbs. 
     This is important in the effectiveness of the expander to expand tissue, not shown, without undue pressure, as may be the case with prior art tissue expanders. A mesh, for example, a polyester mesh  436  adjacent the intermediate layer, may be utilized for strengthening the laminate with the polyester mesh having a thickness also about 0.006 inches. 
     As shown in  FIG. 1 , the tissue expander  10  includes no filling port area with the entire expander  10  having a self-healing characteristics for sealing any hole created by a hypodermic needle when the saline  20  filling process is complete and the needle is removed. 
     The materials of the present invention also enable mandrel forming of the expander  10 . 
     In that regard, the expander  10  is formed on a mandrel (not shown) having a contoured surface that substantially conforms to a desired shape of the tissue expander  10 . 
     The base layer  24  is coated on the mandrel with a plurality of coats to establish a thickness of about 0.006 inches. The silicone layer  28  is thereafter coated onto the base layer and mandrel and cured with a thickness of about 0.1 inches to 0.12 inches. The mesh  36  may be disposed over the silicone layer  28  and secured thereto by curing of the silicone layer  28 . 
     Thereafter the layer  32  is coated onto the underlying base layer, silicone layer, and mesh to a thickness of about 0.006 inches. 
     The layers  24 ,  28 ,  32  may be cured in a conventional manner. 
     As hereinabove noted, the total thickness of the base layer  24 , silicone layer  28 , and top layer  32  enable an internal chamber pressure of about 2.5 psi with an expander exterior compressor force of about 40 lbs. 
     As illustrated in  FIG. 23 , implant  310 , in some embodiments can further include assembly  314  elevated above implant back  334 . Such an elevation can produce space  336  filled by gel layer  26 . Many manufacturing steps and designs can result in space  336  being form along at least a portion of the inside of implant back  334 . For implant  310 , space  336  may be created by at least part of the thickness of plug  337  and/or spacer  340 . 
     Intermediate layer  26  may be filled with gel material using an opening preferentially located on implant back  334 . After intermediate layer  26  is filled with gel material, the opening can be sealed by attaching a plug ( FIGS. 11 &amp; 23 ). A plug can be any geometric shape suitable to seal the opening. In one embodiment, a plug can be cylindrical and have a diameter of at least about 1 cm, at least about 2 cm, at least about 3 cm, at least about 4 cm, at least about 5 cm. In one embodiment, a plug can be cylindrical and have a diameter of between about 1 cm and about 5 cm, about 1.5 cm and about 5 cm, about 2 cm and about 5 cm, about 1 cm and about 6 cm, about 1.5 cm and about 6 cm, about 2 cm and about 6 cm, about 2.5 cm and about 6 cm, or about 3 cm and about 6 cm. 
     In one embodiment, plug  337  comprises a base portion  338  and a lip portion  339  that extends beyond base portion  338  and configured to secure plug  337  to assembly  314 . Inflatable portion  312  can be sealed to base portion  338  along its circumference, the lip portion  339  along their circumference, or both along their circumferences. Plug  337  can also be attached to assembly  314  or a portion thereof. However, in some embodiments, plug  337  is not attached to assembly  314 . Regardless of whether plug  337  is attached to assembly  314 , space  336  can be created by at least part of the thickness of plug  337 . 
     In one embodiment, base portion  338  can be cylindrical and have a diameter of at least about 1 cm, at least about 2 cm, at least about 3 cm, at least about 4 cm, at least about 5 cm. In one embodiment, a plug can be cylindrical and have a diameter of between about 1 cm and about 5 cm, about 1.5 cm and about 5 cm, about 2 cm and about 5 cm, about 1 cm and about 6 cm, about 1.5 cm and about 6 cm, about 2 cm and about 6 cm, about 2.5 cm and about 6 cm, or about 3 cm and about 6 cm. 
     In one embodiment, lip portion  339  can be cylindrical and extends beyond base portion  338  by at least about 1 mm, at least about 2 mm, at least about 3 mm, at least about 4 mm, at least about 5 mm, at least about 6 mm, at least about 7 mm, at least about 8 mm, at least about 9 mm, at least about 10 mm, at least about 12 mm, at least about 15 mm, or at least about 20 mm. In another embodiment, lip portion  339  can be cylindrical and extends beyond base portion  338  by between about 2 mm and about 10 mm, between about 2 mm and about 15 mm, between about 2 mm and about 20 mm, between about 4 mm and about 10 mm, between about 4 mm and about 15 mm, between about 4 mm and about 20 mm, between about 5 mm and about 10 mm, between about 5 mm and about 15 mm, or between about 5 mm and about 20 mm. 
     In one embodiment, the at least part of the thickness of plug  337  comprises the thickness of lip portion  339 . In aspects of this embodiment, the thickness of lip portion  339  is about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, or about 10 mm. In other aspects of this embodiment, the thickness of lip portion  339  is about 1 mm to about 2 mm, about 1 mm to about 3 mm, about 1 mm to about 4 mm, about 1 mm to about 5 mm, about 1 mm to about 6 mm, about 1 mm to about 7 mm, about 1 mm to about 8 mm, about 1 mm to about 9 mm, or about 1 mm to about 10 mm. 
     In some implants, a space between a puncture proof assembly and the implant&#39;s rear can cause buckling when inflating the inflatable portion  12 . Also, movement of the implant when a patient naturally moves can create folds and potentially undesirable appearance of the implant. In order to eliminate, substantially reduce, or reduce this buckling during inflation and/or folds during movement, at least one spacer  340  can be placed between assembly  314  and implant back  334 . Spacer  340  is attached to the assembly  314 , to implant back  334 , or both the assembly  314 , to implant back  334 . As one skilled in the art will appreciate, any number or size of spacers  340  can be used. 
     A spacer can be formed of any material that provides structural support to aid in eliminating, substantially reducing, or reducing buckling and/or folding. Suitable materials can be epoxy, rubber, ceramic or metal, or suitable combination or alloy thereof. For some applications, suitable materials include silicone, polyethylene (PE), polypropylene (PP), polyurethane (PU), polyethylene terephthalate (PET), piolycarbonate (PC), polyisoprene (PI), thermoplastic urethanes and thermoplastic polyurethanes (TPU), high durometer silicones, acrylonitrile butadiene styrene (ABS), and the like. In some embodiments, spacers are made of silicone. 
     In one embodiment, at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, at least ten, one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, or fourteen spacers can be used. In one embodiment, four spacers are used. 
     Spacers can be any shape that aids in eliminating, substantially reducing, or reducing buckling and/or folding. Shapes can be cylindrical, cubic, trapezoidal, triangular, ring shaped, or the like. In one embodiment, the spacers can be cylindrical and have a diameter of at least about 1 mm, at least about 2 mm, at least about 3 mm, at least about 4 mm, at least about 5 mm, at least about 10 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, between about 2 mm and about 10 mm, between about 4 mm and about 8 mm, between about 8 mm and about 12 mm, between about 1 mm and about 12 mm, between about 5 mm and about 10 mm, between about 5 mm and about 12 mm, between about 5 mm and about 15 mm, or between about 5 mm and about 20 mm. 
     The thickness of a spacer can be determined by the size of space  336 . In one embodiment, a spacer&#39;s thickness can be manufactured to match about the size of space  336 . In aspects of this embodiment, the thickness of spacer  340  is about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, or about 10 mm. In other aspects of this embodiment, the thickness of spacer  340  is at least 1 mm, at least 2 mm, at least 3 mm, at least 4 mm, at least 5 mm, at least 6 mm, at least 7 mm, at least 8 mm, at least 9 mm, or at least 10 mm. In yet other aspects of this embodiment, the thickness of spacer  340  is about 1 mm to about 2 mm, about 1 mm to about 3 mm, about 1 mm to about 4 mm, about 1 mm to about 5 mm, about 1 mm to about 6 mm, about 1 mm to about 7 mm, about 1 mm to about 8 mm, about 1 mm to about 9 mm, about 1 mm to about 10 mm, about 1 mm to about 12 mm, about 1 mm to about 15 mm, about 1 mm to about 20 mm, about 2 mm to about 3 mm, about 2 mm to about 4 mm, about 2 mm to about 5 mm, about 2 mm to about 6 mm, about 2 mm to about 7 mm, about 2 mm to about 8 mm, about 2 mm to about 9 mm, about 1 mm to about 10 mm, about 1 mm to about 12 mm, about 1 mm to about 15 mm, about 1 mm to about 20 mm, about 3 mm to about 4 mm, about 3 mm to about 5 mm, about 3 mm to about 6 mm, about 3 mm to about 7 mm, about 3 mm to about 8 mm, about 3 mm to about 9 mm, about 3 mm to about 10 mm, about 3 mm to about 12 mm, about 3 mm to about 15 mm, or about 3 mm to about 20 mm. 
     On skilled in the art will also appreciate that as an implant increases in size, the larger a needed area  342  may become. As such, more spacers can be used with a larger implant. Alternatively, fewer spacers can be used with a smaller implant. The number, size and/or shape of spacers may not impair other desired characteristics of an implant as described herein. For example, spacers may not impair the foldability achieved by assembly  314 . 
     As illustrated in  FIG. 23B , four ring shaped spacers  340 ,  340 ′,  340 ″,  340 ′″ are located within implant  310 . Spacers  340 ,  340 ′,  340 ″,  340 ′″ can be symmetrically oriented around plug  337  or can be placed unsymmetrical around plug  337 . In one embodiment in  FIG. 23B , spacers  340  and  340 ′″ are spaced evenly  344  from plug  337  and spacers  340 ′ and  340 ″ are also evenly spaced  346  from plug  337 , but are these even distances are different. On skilled in the art can achieve different configurations depending on implant size, implant shape, patent shape, or the like. 
     Implants described herein can undergo quality control testing once manufactured. In one test, inner shell  24  can be filled with a gas such as CO 2  and then imaged. In one embodiment, fill ring can be used to aid in the filling of the inner chamber with CO 2 . As illustrated in  FIG. 24 , fill ring  348  can be located on inner wall  350  of inner shell  24 . In one embodiment, fill ring  348  can be located above assembly  314  to prevent rupture during filling with CO 2 . In one preferred embodiment, fill ring  348  can be located on inner wall  350  of inner shell  24  near the wide end of implant  310  for a shaped anatomical version. 
     As illustrated in  FIG. 24  fill ring  348  can be used to accept cannula or needle  502  in a deflated implant  500 . As inner shell  24  is being filled with CO 2 , without fill ring  348 , there would be little to no physical space to start injecting CO 2 . Fill ring  348  can allow physical space or air  504  to exist where needle  502  can be accepted. Further assembly  314  can be used to prevent needle  502  from rupturing deflated implant  500 . 
     When testing of a newly manufactured implant is completed, a gas such as CO 2  may remain in the implant. This remnant gas can aid in filling the implant with saline or other fluid or gel. In some embodiments, fill ring  348  is used for CO 2  inflation only and is not used to saline fill an implant. In other embodiments, fill ring  348  is used for both CO 2  inflation and saline fill of an implant. 
     When deflated implant  500  is eventually implanted and filled with a substance such as saline, fill ring can remain in the implant and remain unnoticed from the exterior of the body. When fill ring  348  is located on inner wall  350  of inner shell  24  above assembly  314 , it can be most concealed. 
     A fill ring can be formed of any material that provides structural support. Suitable materials can be epoxy, rubber, ceramic or metal, or suitable combination or alloy thereof. For some applications, suitable materials include silicone, polyethylene (PE), polypropylene (PP), polyurethane (PU), polyethylene terephthalate (PET), piolycarbonate (PC), polyisoprene (PI), thermoplastic urethanes and thermoplastic polyurethanes (TPU), high durometer silicones, acrylonitrile butadiene styrene (ABS), and the like. In some embodiments, fill rings are formed of silicone. 
     In one embodiment, multiple fill rings can be used. 
     Fill ring  348  can take the shape of a ring, but can also take any other shape. Shapes can be cylindrical, cubic, trapezoidal, triangular, ring shaped, or the like as long as it allows physical space or air  504  to exist. In one embodiment, a fill ring can be ring shaped and have a diameter of at least about 1 mm, at least about 2 mm, at least about 5 mm, at least about 10 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, between about 2 mm and about 10 mm, between about 4 mm and about 8 mm, between about 8 mm and about 12 mm, or between about 1 mm and about 12 mm. The thickness of a fill ring can be about 0.5 mm, about 0.75 mm, about 1 mm, about 1.25 mm, about 1.5 mm, about 1.75 mm, about 2 mm, about 2.25 mm, about 2.5 mm, about 2.75 mm, about 3 mm, about 3.25 mm, about 3.5 mm, about 3.75 mm, or about 4 mm. 
     In another embodiment, fill ring  348  can be attached to front inner surface  352  of inner shell  24 . In other embodiments, fill ring  348  can be located at virtually any position within or on implant  310  to aid in guiding and/or receiving needle  502 . In one embodiment, fill ring  348  can be embedded within inner shell  24  with a resealable membrane in its center. Such an arrangement can allow for guidance of needle  502  through fill ring&#39;s center while allowing fill ring to reside within inner shell  24  thereby reducing its sense of existence. 
     While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the invention.