Abstract:
A multi-chamber balloon for a nuclear implant has an elastomeric membrane defining inner and outer chambers integral with a valve body. The valve body includes a core portion and sealing membrane for sealing the inner and outer chambers. An assembly for manufacturing the multi-chamber balloon includes a balloon mandrel which may be dip coated in a silicone dispersion to create an elastomeric membrane for the inner and outer chambers integral with the valve body. The elastomeric membrane formed on the mandrel is partially inverted to form a coaxial elastomeric structure with the smaller inner chamber disposed within the larger outer chamber. The valve is incorporated into the inner and outer chambers to form a unitary structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/074,925, filed Nov. 4, 2014, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    This application relates generally to methods and devices for repairing an intervertebral disc. More specifically, the application relates to a percutaneously deployed implantable disc replacement and methods for manufacturing such a disc replacement/prosthesis. 
         [0004]    2. Description of Related Art 
         [0005]    A common medical issue is back pain due to spinal disc injuries caused by trauma, the aging process or other disorders. One method of treatment that has been proposed is to remove the existing nucleus pulposus and replace it with a nuclear prosthesis formed in situ using open surgery or minimally invasive surgical techniques. One proposed method comprises the steps of (i) providing a mold, such as a balloon, to contain a flowable curable material that can cure in situ within the disc space, (ii) providing a conduit to connect the mold cavity to a source of flowable curable material, (iii) delivering the flowable curable material into the mold to fill the cavity, and (iv) permitting the curable material to cure. 
         [0006]    The existing techniques for forming a nuclear prosthesis in situ have not achieved convincing clinical acceptance or commercial success. One problem identified by the present inventors is the substantial difference in the modulus of elasticity between the vertebral bony elements, including the vertebral end plates, and the annulus fibrosus on the one hand, and the implanted elements on the other. The high modulus of elasticity of the implanted material is disadvantageous since it does not dampen impacts or sudden increases in intradiscal pressure during extreme bending or torsion, especially during high loading peaks. The large difference in the modulus of elasticity between implanted disc materials and adjacent tissues can also lead to softening of the vertebral end plates and adjacent bone (spongeosus), resulting in subsidence of the nuclear implant. Migration and expulsion of the implant can also occur. 
         [0007]    Therefore, there is a need for an improved nuclear implant. 
       SUMMARY 
       [0008]    An object of exemplary embodiments of the present invention is to provide a method of manufacturing an elastomeric enclosure for a multi-chamber nuclear implant that can selectively and controllably be inflated and deflated with materials that, together, provide physical and mechanical properties similar to those of a normal disc, and which can be tailored to individual patient parameters. 
         [0009]    Another object of exemplary embodiments of the present invention is to provide a method of fabricating a nuclear implant that can be deployed percutaneously in a disc cavity and inflated to conform to the shape and size of the disc cavity. 
         [0010]    A further object of exemplary embodiments of the present invention is to provide a nuclear implant which reinforces the annulus fibrosus if it is torn. 
         [0011]    According to an exemplary embodiment, an implantable prosthetic device comprises an inner inflatable enclosure having a first opening and an outer inflatable enclosure having a first opening. The outer inflatable enclosure encapsulates the inner inflatable enclosure. A valve assembly sealingly couples the first opening of the outer inflatable enclosure and the first opening of the inner inflatable enclosure, and the valve assembly is configured to allow independent inflation of the outer and inner inflatable enclosures. An annular reinforcement band is provided around the periphery of the outer inflatable enclosure. When implanted, the inner chamber is filled with a compressible material and the outer inflatable enclosure is filled with an in situ curable material, such as silicone. This structure allows for vertical and horizontal load stresses placed on the implant to be redirected inward, centrally toward the inner compressible enclosure instead of outward. 
         [0012]    The inner and outer inflatable enclosures may comprise a seamless, unitary piece of material. The inner inflatable enclosure may have a second opening generally opposite of the first opening, the outer inflatable enclosure may have a second opening generally opposite of the first opening, and a plug may sealingly couple the second opening of the inner inflatable enclosure and the second opening of the outer inflatable enclosure. The plug may be coupled to a neck portion of the second opening of the outer inflatable enclosure. The plug and the neck portion of the second opening of the outer inflatable enclosure may be coupled to a neck portion of the second opening of the inner inflatable enclosure. 
         [0013]    The annular reinforcement band may be placed into the second opening of the inner inflatable enclosure and then the distal plug may be inserted into the second opening to couple the reinforcement band to the balloon. The reinforcement band may be coupled to the inflatable enclosure at only one location, such as at the plug. A fastener may be provided to fasten the reinforcement band to the plug. The reinforcement band may include a shape memory material. The annular reinforcement band may comprise a tubular braid enclosing the shape memory material. 
         [0014]    The valve assembly may comprise a valve core coupling the first openings of the outer and inner inflatable enclosures. The valve core has an opening from an interior of the valve core to an exterior of the valve core. A valve membrane partially envelops the valve core and has an opening into the outer inflatable enclosure. The opening in the valve membrane and the valve core are separated from one another to allow material to flow into the outer inflatable enclosure, while preventing backflow. The valve core may further comprise a resealable, puncturable membrane to provide access to the inner inflatable enclosure. 
         [0015]    The valve membrane and the valve core may be integrally molded, or the valve core may be bonded to the valve membrane with an adhesive. 
         [0016]    The inner and outer inflatable enclosures may comprise an elastomer, such as silicone rubber. 
         [0017]    In some embodiments, a curable material may be provided to inflate the outer inflatable enclosure, and a compressible material such as gas may be provided to inflate the inner inflatable enclosure to allow the cured material to deform. The cured material may substantially surround the inner inflatable enclosure. In other embodiments, an incompressible material (e.g., a liquid) is provided to inflate the inner inflatable enclosure and then the curable material is injected into the outer inflatable enclosure. The incompressible material is then removed from the inner inflatable enclosure and replaced with a compressible material (e.g., a gas). In certain embodiments, the curable material further polymerizes with the inner and outer inflatable enclosures to form a solid, unitary member. 
         [0018]    In accordance with an exemplary embodiment, a valve assembly for inflating an implantable prosthetic device comprising an inner inflatable enclosure connected to an outer inflatable enclosure comprises an elastomeric membrane forming a passageway from an interior of the inner inflatable enclosure to an exterior of the outer inflatable enclosure and a valve core disposed in the passageway so that the elastomeric membrane surrounds the valve core. The elastomeric membrane has an opening into an interior of the outer inflatable enclosure, and the elastomeric membrane surrounds the valve core. The valve core comprises a conduit extending from a first end to a second end, and a resealable, puncturable membrane at the second end of the valve core conduit for providing resealable access to the inner inflatable enclosure. An opening in the conduit extends from an interior of the conduit to an exterior of the conduit, and the opening in the valve core is offset from the opening in the elastomeric membrane to form a one way valve allowing material introduced into the interior of the conduit to pass into the interior of the outer inflatable enclosure while preventing backflow. 
         [0019]    In accordance with an exemplary embodiment, a method of implanting a prosthetic device into an intervertebral space having a nucleus pulposus surrounded by an annulus fibrosus comprises penetrating the annulus fibrosus, removing the nucleus pulposus, and implanting an implantable prosthetic device, wherein the implantable prosthetic device comprises an inner inflatable enclosure having a first opening and an outer inflatable enclosure having a first opening. The outer inflatable enclosure encapsulates the inner inflatable enclosure. A valve assembly sealingly couples the first opening of the outer inflatable enclosure and the first opening of the inner inflatable enclosure, and the valve assembly is configured to allow independent inflation of the outer and inner inflatable enclosures. A reinforcement band is provided around the periphery of the outer inflatable enclosure. 
         [0020]    In some embodiments, the method may further comprise inflating the inner inflatable enclosure using a compressible material, and the compressible material may comprise a gas. The method may further comprise inflating the outer inflatable enclosure using a curable material, and the curable material may be silicone rubber. In other embodiments, the method may further comprise inflating the inner inflatable enclosure using an incompressible material, and the incompressible material may comprise a liquid. The method may further comprise inflating the outer inflatable enclosure using a curable material, allowing the curable material to cure, and then replacing the incompressible material in the inner inflatable enclosure with a compressible material. 
         [0021]    In accordance with an exemplary embodiment, a method of producing an implantable prosthetic device comprises (i) injection molding a prosthesis blank comprising an outer membrane section with a proximal end and a distal end, an inner membrane section with a proximal end and a distal end, a valve section disposed between the proximal end of the outer membrane section and the proximal end of the inner membrane section, a distal plug inner section at the distal end of the inner membrane section, and a distal plug outer section at the distal end of the outer membrane section; and (ii) partially inverting the prosthesis blank so that the outer membrane section encloses the inner membrane section to form an outer balloon surrounding an inner balloon formed by the inner membrane. 
         [0022]    In accordance with an exemplary embodiment, a method of producing an implantable prosthetic device comprises (i) providing a mandrel with a profiled outer surface configured to form a prosthesis blank comprising an outer membrane section with a proximal end and a distal end, an inner membrane section with a proximal end and a distal end, a valve section disposed between the proximal end of the outer membrane section and the proximal end of the inner membrane section, a distal plug inner section at the distal end of the inner membrane section, and a distal plug outer section at the distal end of the outer membrane section; (ii) coating the mandrel with a material to form the prosthesis blank; (iii) stripping the prosthesis blank from the mandrel; and (iv) partially inverting the prosthesis blank so that the outer membrane section encloses the inner membrane section to form an outer balloon surrounding an inner balloon formed by the inner membrane. 
         [0023]    The mandrel may comprise a unitary body, and the valve section of the mandrel may comprise a valve core that is integrally molded with the prosthesis blank. The mandrel may comprise two separable pieces coupled to the valve core, and the step of stripping the prosthesis blank from the mandrel may comprise separating the mandrel pieces from the valve core and removing the separable pieces from the prosthesis blank. 
         [0024]    The valve core may be glued into the valve section. 
         [0025]    The distal plug may be inserted into the distal plug outer section to seal the distal plug outer section, and the distal plug and distal plug outer section may be inserted into the distal plug inner section. 
         [0026]    A reinforcing band may be joined to the distal plug, and the reinforcing band, distal plug, and distal plug outer section may be inserted into the distal plug inner section. The reinforcing band may be joined to the distal plug with a fastener. 
         [0027]    The mandrel may be coated by dipping it into a polymer liquid, which may comprise a silicone dispersion, and dried. 
         [0028]    The elastomeric membrane may be stripped from the mandrel by melting the mandrel, or the prosthesis blank may be removed from the mandrel by stretching it over the mandrel. A reinforcing band may be applied around the periphery of the outer balloon. 
         [0029]    In accordance with an exemplary embodiment, a mandrel for producing an implantable prosthetic device comprises a first balloon mandrel with a profiled outer surface configured in the shape of a first balloon; a second balloon mandrel with a profiled outer surface configured in the shape of a second balloon; and a valve core disposed between the first and second balloon mandrels. The outer surface of the first balloon mandrel may further comprises a distal opening section, and the outer surface of the second balloon mandrel may further comprise a distal opening section. The outer surfaces of the balloon mandrels may be curved. The outer surfaces of each of the balloon mandrels may comprise a central section with a generally uniform diameter. 
         [0030]    In accordance with an exemplary embodiment, a mandrel for producing an implantable prosthetic device comprises a unitary body with a profiled outer surface. The profiled outer surface has an outer membrane section configured to form an annular balloon with a proximal end and a distal end; an inner membrane section configured to form a nuclear balloon with a proximal end and a distal end; a valve section configured to receive a valve assembly disposed between the proximal end of the outer membrane section and the proximal end of the inner membrane section; a distal plug outer section configured to receive a distal plug at the distal end of the outer membrane section; and a distal plug inner section configured to receive an assembly of the distal plug and distal plug outer section at the distal end of the inner membrane section. 
         [0031]    The term “coupled” is defined as connected, although not necessarily directly. The terms “a” and “an” are defined as one or more unless this disclosure explicitly requires otherwise. The terms “substantially,” “approximately,” and “about” are defined as largely but not necessarily wholly what is specified (and includes what is specified; e.g., substantially 90 degrees includes 90 degrees and substantially parallel includes parallel), as understood by a person of ordinary skill in the art. In any disclosed embodiment, the terms “substantially,” “approximately,” and “about” may be substituted with “within [a percentage] of” what is specified, where the percentage includes 0.1, 1, 5, and 10 percent. 
         [0032]    The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a system, or a component of a system, that “comprises,” “has,” “includes” or “contains” one or more elements or features possesses those one or more elements or features, but is not limited to possessing only those elements or features. Likewise, a method that “comprises,” “has,” “includes” or “contains” one or more steps possesses those one or more steps, but is not limited to possessing only those one or more steps. Additionally, terms such as “first” and “second” are used only to differentiate structures or features, and not to limit the different structures or features to a particular order. 
         [0033]    A device, system, or component of either that is configured in a certain way is configured in at least that way, but it can also be configured in other ways than those specifically described. 
         [0034]    Any embodiment of any of the systems and methods can consist of or consist essentially of—rather than comprise/include/contain/have—any of the described elements, features, and/or steps. Thus, in any of the claims, the term “consisting of” or “consisting essentially of” can be substituted for any of the open-ended linking verbs recited above, in order to change the scope of a given claim from what it would otherwise be using the open-ended linking verb. 
         [0035]    The feature or features of one embodiment may be applied to other embodiments, even though not described or illustrated, unless expressly prohibited by this disclosure or the nature of the embodiments. 
         [0036]    Details associated with the embodiments described above and others are presented below. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0037]      FIG. 1  is a perspective view of an inflated implant in accordance with an embodiment of the present invention; 
           [0038]      FIG. 2  is a perspective view of the inflated implant of  FIG. 1  from another direction; 
           [0039]      FIG. 3  is a top view of the implant of  FIG. 1 ; 
           [0040]      FIG. 4  is a sectional view taken through line  4 - 4  in  FIG. 2 ; 
           [0041]      FIG. 5  is a sectional view taken through line  5 - 5  in  FIG. 2 ; 
           [0042]      FIG. 6  is a cut-away view of a portion of an implant valve of the implant of  FIG. 1 ; 
           [0043]      FIG. 7  is a cut-away view of a portion of the implant valve of  FIG. 6 ; 
           [0044]      FIG. 8  is a sectional view of an implant assembly prior to insertion of a distal plug and attachment of an annular reinforcing member; 
           [0045]      FIG. 9  is a sectional view of a mandrel and implant according to an embodiment of the present invention; 
           [0046]      FIG. 10  illustrates a first assembly step for the implant assembly of  FIG. 1 ; 
           [0047]      FIG. 11  illustrates a second assembly step for the implant assembly of  FIG. 1 ; 
           [0048]      FIG. 12  illustrates a third assembly step for the implant assembly of  FIG. 1 ; 
           [0049]      FIG. 13  illustrates a fourth assembly step for the implant assembly of  FIG. 1 ; 
           [0050]      FIG. 14  is a sectional view of a mandrel and implant assembly according to another embodiment of the present invention; 
           [0051]      FIG. 15  illustrates a first assembly step for the implant assembly of  FIG. 1 ; 
           [0052]      FIG. 16  illustrates a second assembly step for the implant assembly of  FIG. 1 ; 
           [0053]      FIG. 17  illustrates a third assembly step for the implant assembly of  FIG. 1 ; 
           [0054]      FIG. 18  illustrates a fourth assembly step for the implant assembly of  FIG. 1 ; 
           [0055]      FIG. 19  illustrates a final assembly step for the implant assembly of  FIG. 1 ; 
           [0056]      FIG. 20  illustrates a first step in implanting the implant assembly of  FIG. 1 ; 
           [0057]      FIG. 21  illustrates a second step in implanting the implant assembly of  FIG. 1 ; 
           [0058]      FIG. 22  illustrates a third step in implanting the implant assembly of  FIG. 1 ; and 
           [0059]      FIG. 23  illustrates a fourth step in implanting the implant assembly of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0060]    In the following detailed description, reference is made to the accompanying drawings, in which are shown exemplary but non-limiting and non-exhaustive embodiments of the invention. These embodiments are described in sufficient detail to enable those having skill in the art to practice the invention, and it is understood that other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the invention is defined only by the appended claims. In the accompanying drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified. 
       Description of Implant 
       [0061]    Referring to  FIGS. 1-8 , an embodiment of a percutaneously deliverable spinal implant  100  includes an outer inflatable enclosure (or balloon)  102  and an inner inflatable enclosure (or balloon)  104 . Outer inflatable enclosure  102  forms an annular chamber  106 , and inner inflatable enclosure  104  forms a nuclear chamber  108 . Nuclear chamber  108  is encapsulated within annular chamber  106 . Preferably, outer and inner inflatable enclosures  102 ,  104  are formed as a seamless, unitary piece of an elastomeric material, such as silicone rubber. The use of an elastomeric material produces compliant outer and inner balloons  102 ,  104 . That is, the outer and inner balloons  102 ,  104  expand when internal pressure is applied. The use of compliant balloons provides certain advantages. Compliant balloons accommodate the irregular, flat or discoid configuration of the nuclear space. Furthermore, a compliant balloon maintains an appropriate modulus of elasticity of the nuclear implant following elastomeric curing, and preserve bio-mechanical mobility of the vertebral segment, and allows unhindered deformation of the cured silicone component into the central void. 
         [0062]    An annular reinforcing band  110  may be disposed around the perimeter of the lateral edges of implant  100  to minimize or prevent over-stretching of the elastomeric membrane or over inflation of outer and inner balloons  102 ,  104  circumferentially. Annular reinforcement band  110  encourages vertical expansion to widen the disc space. The vertebral superior and inferior end plates constrain the expansion of the implant  100 . 
         [0063]    The size of implant  100  is selected so that it can be percutaneously inserted into a denucleated intervertebral disc space while deflated and then inflated to fill the denucleated cavity. In one embodiment, the exterior of inflated implant  100  is approximately 30 mm in length, 20 mm in width, and 10 mm in height, and the exterior of inner inflatable enclosure  104  is approximately 9 mm long, 6 mm wide, and 6 mm thick. 
         [0064]    Annular reinforcing band  110  may be a biocompatible textile material. In one embodiment, annular reinforcing band  110  comprises a tubular, woven textile material. Annular reinforcing band  110  may also include an expandable member to provide additional support. The expandable member may be formed of a shape memory material, such as nitinol. U.S. Pat. No. 8,636,803, entitled Percutaneous Implantable Nuclear Implant, discloses one suitable construction of annular reinforcing band  110 , and is hereby incorporated by reference in its entirety for all purposes. 
         [0065]    Outer inflatable enclosure  102  has a first opening  118  and a second opening  120 . Inner inflatable enclosure  104  has a first opening  136  and a second opening  138 . A proximal plug, or valve core,  112  connects first opening  118  and first opening  136 . A valve membrane  122  surrounds proximal plug  112  and cooperates with proximal plug  112  to form an inflation valve  124 . Inflation valve  124  is a one-way valve which allows material to be introduced into annular chamber  106 . Preferably, valve membrane  122  is formed integrally with outer and inner inflatable enclosures  102 ,  104 , as will be described in further detail below. As seen most clearly in  FIGS. 6-8 , proximal plug  112  comprises a conduit  126  extending from a first end  128  to a second end  130 . First end  128  of proximal plug  112  forms a port  114  for receiving an inflation stylus  116 . Valve membrane  122  is coupled to proximal plug  112  by first and second adhesive bands  140 ,  142 , which are substantially fluid tight. The portion of valve membrane  122  between first and second adhesive bands  140 ,  142  is unbonded to form a channel for allowing material to flow therethrough. At least one opening  132  extends from conduit  126  to the exterior of proximal plug  112 . Valve membrane  122  has at least one opening  134  which is offset from opening  132 . In this manner, when a suitable material (described in detail below) is introduced into conduit  126  under pressure, the material is introduced through opening  132  into annular chamber  106 , stretches valve membrane  122 , and flows out through opening  134 . When pressure is removed from conduit  126 , valve membrane  122  seals opening  132  and prevents backflow through opening  132 . Second end  130  of conduit  126  is closed by a puncturable, resealable membrane  144 . 
         [0066]    A distal plug  146  is disposed in a neck portion  148  extending from second opening  138  of the inner inflatable enclosure  104 . The distal plug  148  is bonded to the neck portion  148  to form a fluid tight seal. The distal plug  146  and neck portion  148  assembly is disposed within a neck portion  150  extending from second opening  120  of outer inflatable enclosure  102 . Annular reinforcing band  110  may be trapped between the distal plug  146  and neck portion  148  assembly and the neck portion  150  to serve as an anchor for reinforcing band  110 . Alternatively, a fastener  152  may be used to anchor annular reinforcing band  110  to distal plug  146 , as seen most clearly in  FIG. 9 . 
       Method of Manufacturing The Implant 
       [0067]    Referring to  FIGS. 9-13 , in one embodiment, inner and outer inflatable enclosures  102 ,  104  are formed from a unitary implant blank  154 . Implant blank  154  may be produced by dip molding using a mandrel  156 . Mandrel  156  comprises an outer membrane section  158 , an inner membrane section  160 , and a valve section  162 . Mandrel  156  may be one piece or multiple pieces. In one embodiment, outer membrane section  158 , inner membrane section  160 , and valve section  162  are separate pieces which are assembled together. Mandrel  156  is dipped into a polymer liquid, such as a silicone dispersion, removed from the liquid and allowed to dry or cure. Mandrel  156  may be dipped one or more times to build up a desired thickness of material. The blank  154  comprises neck portion  150 , outer inflatable enclosure  102 , valve membrane  122 , inner inflatable enclosure  104 , and neck portion  148 . 
         [0068]    After curing or drying, implant blank  154  is stripped from mandrel  156 . This may be accomplished by stretching implant blank  154  over mandrel  156 . If mandrel  156  is composed of separable pieces, it may be disassembled prior to stripping. In one embodiment, mandrel  156  may be formed of a meltable or dissolvable material and melted or dissolved to strip implant blank  154  from mandrel  156 . Opening  134  through valve membrane  122  is formed in implant blank  154 . 
         [0069]    Referring to  FIGS. 10-13 , implant blank  154 , distal plug  146  and proximal plug (or valve core)  112  are provided. Neck portion  148  which extends from inner inflatable enclosure  104  is inverted into the interior of inner inflatable enclosure  104  and distal plug  146  is inserted into neck portion  148  and glued into place. The neck portion is the further inverted into the annular chamber  106 . Next, proximal plug  112  is inserted and glued into the valve membrane  122 . This is done in two steps. First, the end of proximal plug  112  nearest the annular chamber  106  is glued to valve membrane  122  with first adhesive band  142 . Next, the implant blank  154  is further inverted, and second adhesive band  142  is applied to glue implant blank  154  to the second end of proximal plug  112 . This results in the configuration shown in  FIG. 12 . Next, neck portion  150  is tucked into outer inflatable enclosure  102  (as indicated by the arrows in  FIG. 8 ) and over distal plug  146  and neck portion  148 , as shown in  FIG. 13 . Annular reinforcing band  110  may be tucked in at the same time, or may be fastened to distal plug  146  by a fastener. 
         [0070]    In another embodiment, implant blank  154  is formed by injection molding over a mandrel using conventional techniques. That is, the mandrel is placed into an injection mold having a cavity corresponding to the outer shape of the implant blank, and a curable material is injected into the mold under pressure. The curable material is allowed to cure, thereby forming implant blank  154  over the mandrel. The mandrel and implant blank  154  are then removed from the injection mold. Once implant blank  154  is formed, the remaining assembly steps are as described in the prior paragraph. 
         [0071]      FIGS. 14-19  illustrate another method of making an implant  100 . In this embodiment, a mandrel  164  comprises a first mandrel section  166  forming an outer membrane section  168  and a second mandrel section  168  forming an inner membrane section  170 . First mandrel section  166  is inserted into valve core (or proximal plug)  112 , and second mandrel section is mated with the other end of proximal plug  112 . Referring to  FIG. 15 , the mandrel and valve assembly is then dip molded to form an implant blank  176 . Referring to  FIG. 16 , the neck portion  188  of the implant blank  176  is inverted and a proximal plug is glued into the neck portion  188 . A valve membrane  192  is applied over the plug section and adhered to the plug section with first and second adhesive bands to form an implant valve. The implant blank  176  is then inverted left to right over the valve core  112 , as shown in  FIG. 18 . Finally, the neck portion  190  tucked into the outer inflatable enclosure  102 . Annular reinforcing band  110  may be tucked in at the same time, or may be fastened to distal plug  146  by a fastener. 
       Method of Deploying an Implant 
       [0072]    Referring to  FIGS. 20-23 , the inflatable implant  100  is particularly well suited for deployment using minimally invasive or percutaneous surgical techniques. To prepare the inflatable implant  100  for deployment, the implant is deflated and stretched to minimize its cross-sectional profile. An insertion stylus  116  is detachably inserted into port  114 , then the implant  100  is inserted into a deployment cannula  180 . Deployment cannula  180  has a minimal cross-sectional profile. 
         [0073]    Referring to  FIG. 20 , to implant the inflatable implant  100 , the existing nucleus pulposus is removed by performing a discectomy while leaving the annulus fibrosus  178  substantially intact. Preferably, the discectomy is performed using minimally invasive surgical techniques, such as percutaneous techniques, which leaves a small opening through the annulus fibrosus  178 . Once the nucleus pulposus has been removed, the annulus fibrosus  178  and vertebral end plates  182 ,  184  form a substantially empty disc cavity  182 . 
         [0074]    After the nucleus pulposus has been removed, deployment cannula  180  with preloaded implant  100  is placed into the empty disc cavity  182 . The implant  100  is deployed by pushing it out of the deployment cannula and into the empty disc cavity, as shown in  FIG. 21 . The implant  100  is in an uninflated state. 
         [0075]    In one embodiment, nuclear chamber  108  is first inflated with a compressible fluid  194 , such as a gas. This may be performed using a needle (not shown) which is delivered through the inflation stylus  116  and pushed through the puncturable, resealable membrane  144 . The compressible fluid is deployed into the nuclear chamber  108  to inflate the inner inflatable enclosure  104 . The pressure of the nuclear chamber  108  is selected so that it provides a buffer zone for inward deformation of the cured elastomer  186  during weight bearing and spine movement. Once nuclear chamber  108  is inflated to the desired pressure, the needle is withdrawn from nuclear chamber  108 . In another embodiment, instead of using a removable needle, inflation stylus  116  may have a septum extending through the stylus to divide the stylus into two lumens. One lumen extends through resealable, puncturable membrane  144  into nuclear chamber  108 , while the other lumen delivers an in situ curable material to implant valve  124  and annular chamber  106 . 
         [0076]    Inflation stylus  116  is used to deliver an in situ curable material to annular chamber  106  through the one way implant valve  124  ( FIG. 22 ). The curable material is preferably an elastomeric material, such as silicone rubber, which further polymerizes with the material of inner and outer inflatable enclosures  102 ,  104  to form a unitary member. The modulus of elasticity and other characteristics of the curable material can be selected based upon patient specific parameters. For instance, younger, more active patients may require a firmer material than less mobile geriatric patients. Once annular chamber  106  is inflated to a desired pressure, inflation stylus  116  can be removed. Implant valve  124  prevents the curable material from leaking out of the annular chamber  106 . 
         [0077]    After the curable material is allowed to cured, the implant  100  comprises an annular ring of a cured elastomer  186  surrounding nuclear chamber  108  which is filled with a compressible material  194 . This structure allows for vertical and horizontal load stresses placed on the intervertebral disc space to be redirected inward, centrally toward nuclear chamber  108  (see direction arrows of  FIG. 23 ) instead of outward. Moreover, annular reinforcing band  110  encourages tissue in-growth of native annulus fibrosus  178 , thereby providing reinforcement to native annulus fibrosus  178 . 
         [0078]    In another embodiment, nuclear chamber  108  is first inflated with an incompressible fluid, such as a liquid. This may be performed using a needle or an inflation stylus, as described above. Once nuclear chamber  194  is inflated, inflation stylus  116  is used to deliver an in situ curable material to annular chamber  106  through the one way implant valve  124 . After the curable material is allowed to cured, the incompressible fluid is removed from nuclear chamber  108  and replaced with compressible material  194 . This may be accomplished with a needle using implant valve  124 . 
         [0079]    The above specification and examples provide a complete description of the structure and use of exemplary embodiments. Although certain embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention. As such, the various illustrative embodiments of the present devices are not intended to be limited to the particular forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and embodiments other than the one shown may include some or all of the features of the depicted embodiment. For example, components may be combined as a unitary structure, and/or connections may be substituted (e.g., threads may be substituted with press-fittings or welds). Further, where appropriate, aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples having comparable or different properties and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. 
         [0080]    The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations, unless such a limitation is explicitly recited in a given claim using the phrase(s) “means for” or “step for,” respectively.