Abstract:
The present disclosure concerns implants to at least partially replace the nucleus of a spinal disc. In one embodiment, a prosthetic implant is provided which includes a bag structure having a fixation component or member, the bag operable to contain at least one internal implant within the bag. In other embodiments, a bag structure is provided with a flange adaptable to anchor the structure to a vertebral body and a sinusoidal-shaped structure made of a flexible material is provided with various unique configurations. In one embodiment, for delivery, a bag structure with a flange may be attached to a vertebral body. In another embodiment, a sinusoidal-shaped implant structure is alternately woven from one end to the other with a second sinusoidal-shaped structure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This is a continuation application that claims the benefit under 35 U.S.C. § 120 of non-provisional U.S. patent application Ser. No. 11/332,622, filed Jan. 13, 2006. The aforementioned application is hereby incorporated by reference for all purposes. 

   FIELD OF THE INVENTION 
   Embodiments of the present invention relate generally to disc replacement therapy. More particularly, embodiments of the present invention relate to methods, devices and materials that may be used in disc replacement therapy procedures. 
   BACKGROUND 
   The spinal column consists of a complex system of bones and connective tissues that provides support for the body and protects the delicate spinal cord and nerves. The spinal column includes a series of vertebrae stacked one on top of the other, each vertebral body includes an inner or central portion of relatively weak cancellous bone and an outer portion of relatively strong cortical bone. Situated between each vertebral body is an intervertebral disc that cushions and dampens compressive forces experienced by to the spinal column. A vertebral canal containing the spinal cord and nerves is located behind the vertebral bodies. 
   The bones and connective tissue of an adult human spinal column consists of more than 20 discrete bones coupled sequentially to one another by a tri-joint complex which consist of an anterior disc and the two posterior facet joints, the anterior discs of adjacent bones cushioned by intervertebral discs. These more than 20 bones are anatomically categorized as being members of one of four classifications: cervical, thoracic, lumbar, or sacral. The cervical portion of the spine, which includes the top of the spine, up to the base of the skull, includes the first 7 vertebrae. The intermediate 12 bones are the thoracic vertebrae, and connect to the lower spine comprising the 5 lumbar vertebrae. The base of the spine is the sacral bone (including the coccyx). The component bones of the cervical spine are generally smaller than those of the thoracic and lumbar spine. Although complex, the spine is a highly flexible structure, capable of a high degree of curvature and twist in nearly every direction. 
   Many types of spinal column disorders affect the function and integrity of the spine such as degenerative disc disease, spondylolisthesis (forward displacement of one vertebra over another, usually in a lumbar or cervical spine), scoliosis (abnormal lateral curvature of the spine), kyphosis (abnormal forward curvature of the spine, usually in the thoracic spine), excess lordosis (abnormal backward curvature of the spine, usually in the lumbar spine) and other disorders caused by abnormalities, disease, or trauma, such as ruptured or slipped discs, degenerative disc disease, fractured vertebra, and the like. Patients that suffer from such conditions usually experience extreme and debilitating pain, as well as diminished nerve function. 
   Spinal pathologies limit the range, and/or threaten the critical elements of the nervous system housed within the spinal column. A variety of systems exist that achieve immobilization by implanting artificial assemblies in or on the spinal column. Lateral and anterior assemblies are coupled to the anterior portion of the spine, which is the sequence of vertebral bodies. Posterior implants generally include pairs of rods that are aligned along the axis which the bones are to be disposed, and which are then attached to the spinal column. 
   One of the most common motion segment surgical interventions is called arthrodesis, or spine fusion. Clinical success varies considerably, depending upon technique and indications, and consideration must be given to the concomitant risks and complications. For example, it has been shown that spine fusion decreases function by limiting the range of motion for patients in flexion, extension, rotation, and lateral bending. Furthermore, it has been shown that spine fusion creates increased stresses and, therefore, accelerated degeneration of adjacent non-fused motion segments. Also, the fusion device, whether artificial or biological, may migrate out of the fusion site. 
   While some disc replacement materials and methods currently are known, further improvements are needed. Thus, needs exist for placement of disc replacement materials and structures that may provide support and preserve motion. 
   SUMMARY 
   In one embodiment, the present invention relates to a prosthetic structure for replacement of at least a portion of the intervertebral disc nucleus. In some embodiments, use of this structure allows the annulus fibrosis to remain substantially intact. The device includes a bag structure made from a flexible material having a cavity therein. The bag structure includes an opening that is in communication with the cavity, and may include a fixation component, which is adapted to allow fixation to vertebral endplates when placed into the cavity. The bag structure with a fixation component is adapted to remain within an intervertebral disc space without extrusion from the space in one example when the fixation component interacts with vertebral bodies. Further, the bag structure may include an interfacing layer wherein the interfacing layer may be situated between a bag structure and a fixation component. In some embodiments, an interfacing layer reduces the contact between a bag structure and a fixation component. 
   In some embodiments, a fixation component may include a mechanical structure, a flexible material and/or an agent. In some embodiments, the flexible material may include a semi-permeable flexible material. In some embodiments, the flexible material of the bag structure may include a material having a metallic property. 
   In some embodiments, a bag structure may have a component such as an anchoring component like a flange. Optionally, the flange may contain holes capable of being used to anchor the bag structure to a vertebral body. 
   Further, in another particular embodiment, the present invention may include implanting a prosthetic bag structure having a fixation component. The annulus may be partially resected, a substantial portion of the disc nucleus may be removed to create a cavity. Vertebral endplates may be prepared by any known method in the art. In accordance with this particular embodiment, a bag structure having a fixation component may be introduced to the cavity and configured to receive an interior implant structure. 
   In yet another embodiment, the present invention relates to another method for implanting a prosthetic structure into an intervertebral space. In accordance with this embodiment, the annulus may remain substantially intact by cutting the annulus to form an opening that is capable of being repositioned to substantially its original position. 
   A more complete understanding of the present invention may be derived by referring to the detailed description of preferred embodiments and claims when considered in connection with the figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the Figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label. 
       FIG. 1  represents a schematic diagram of an implant bag structure; 
       FIG. 2A  represents a schematic diagram of an implant structure in accordance with one embodiment of the present invention; 
       FIG. 2B  is a three dimensional side view of an implant structure in accordance with one embodiment of the present invention; 
       FIG. 2C  is a cross-sectional view of the intervertebral disc nucleus prosthetic bag structure in accordance with one embodiment of the present invention; 
       FIG. 3  is an isometric view partially in cross-sectional view of one embodiment of an intervertebral disc nucleus prosthetic bag structure in accordance with the present invention; 
       FIG. 4  is an isometric view of one embodiment of an intervertebral disc nucleus prosthetic bag structure having an implant structure positioned therein in accordance with the present invention; 
       FIG. 5  is a cross-sectional view of a spinal column showing a herniated disc; 
       FIGS. 6A-6D  are schematic representation of implantation of a prosthetic device in accordance with one embodiment of the present invention; 
       FIG. 7  is a perspective view of a component of an implant structure in accordance with one embodiment of the present invention; 
       FIG. 8A  is a top view of the component depicted in  FIG. 8A  in accordance with one embodiment of the present invention; 
       FIG. 8B  is a side view of the component depicted in  FIG. 8A  in accordance with one embodiment of the present invention; 
       FIG. 9  is a perspective view of an implant structure in accordance with one embodiment of the present invention; 
       FIGS. 10A and 10B  are perspective views of an interior implant structure in accordance with some embodiments of the present invention; 
       FIG. 11  is a fragmentary view of an implant structure in accordance with one embodiment of the present invention; 
       FIG. 12  is a view of an implant structure positioned between two adjacent vertebral bodies in accordance with one embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Embodiments of the present invention relate generally to devices, materials and methods for replacing at least a portion of an intervertebral disc nucleus and in other embodiments replacing all of an intervertebral disc nucleus. More particularly, embodiments of the present invention relate to disc nucleus prosthesis structures, including prosthesis bag structures, implant structures, and a combination of prosthesis bag structures and implant structures. While various prosthetic structures discussed herein are presented with reference to replacement of part or all of a human disc, embodiments of the present invention have application beyond human disc replacement. For example, the prosthetic structures discussed herein could be used in or with discs for any suitable vertebrate animal that might need of a disc replacement. 
   Referring now to  FIGS. 1 and 3 , one embodiment of the present invention includes an intervertebral disc nucleus prosthetic bag structure  100  that may be used for replacing all or part of a diseased, damaged or otherwise non-functional intervertebral disc nucleus. In one embodiment, bag structure  100  includes an outer body  110 , an optional porous fixation plate or component  130 , an optional interfacing layer  140 , an access port  150  and opening  120  for receiving, for example, an interior implant structure or material. 
   In accordance with one embodiment of the invention, bag structure  100 , and in particular, outer body  110  is formed of a flexible material. In other embodiments, a fixation component  130  may be part of or separate from bag structure  100 . For example, fixation component  130  may be associated with upper and lower surfaces of bag structure  100 . Fixation component  130  may be introduced to bag structure  100  subsequent to an interfacing layer  140  which may be made of a material such as a polymer. Interfacing layer  140  may serve as an adhesive between the fixation component  130  and the outer surface of an implant structure such as bag structure  100 . In addition, interfacing layer  140  may be used to reduce contact between the outer surface of bag structure  100  and fixation component  130 . This separation reduces surface contact between fixation component  130  and bag structure  100  that may lead to destruction of an implant structure due to for example contact agitation. 
   While fixation component  130  has several functions, one function of fixation component  130  may be to decrease the movement of the prosthetic implant within a disc nucleus by inducing intervertebral fixation such as inducing bone ingrowth. Reduction in the movement of the implant structure once placed within a nuclear space may preserve relative motion of a subject receiving such an implant by reducing relative motion of the implant and vertebral endplates. In addition, fixation component  130  once fixed to vertebral endplates is capable to transmitting transverse in-plane shear loads. To induce fixation of any prosthetic implant to intervertebral bodies disclosed herein any known methods for preparing vertebral endplates may be used. 
   In some embodiments, bag structure  100 , and in particular, outer body  110  and fixation component  130  may be formed of a semi-permeable flexible, resilient, elastic or viscoelastic material. Some of these materials may have a time dependent deformation quality that dissipates some mechanical energy; thus, there is a viscoelastic quality to the material in some of these examples. Therefore, bag structure  100  and fixation component  130  may be compressed, to facilitate implantation in an annulus fibrosis cavity using a delivery device, such as a catheter or the like. Once inserted into the intervertebral space, bag structure  100  and the fixation component  130  may be released from the delivery device, so that it returns to its relaxed unstretched state. Implantation of the bag structure will be discussed in more detail below. 
   In one embodiment, fixation component  130  of bag structure  100  may be formed of an immunologically inert material that is compatible with the environment found within a mammalian body, and in particular, within an intervertebral disc. As one skilled in the art will appreciate, the immunologically inert material does not induce any significant response by the immune system when the structure is implanted into a subject. Fixation component  130  may be formed of one or more materials, including in some embodiments, one or more porous materials. In addition, outer body  110  of bag structure  100  may be formed from one or more layers of material such as a layer to reduce leakage and/or a layer for fixation. In addition, the shape of the bag structure  100  as viewed from the top may be circular, oval, or other shapes that may fit the shape of the intervertebral space. In addition, the implant may include an eccentricity ratio of about 1.0 to 2.0 in the transverse plane of the disc space, or, in alternative embodiments, may include an eccentricity ratio of about 1.0 to about 3.5. 
   In one embodiment, fixation component  130  may be formed of one or more different materials, which exhibit porous properties. That is porous material of fixation component  130  that induce ingrowth of cellular material such as bone ingrowth as discussed previously. In addition, fixation component  130  may be coated with an agent. For example, an agent for coating fixation component  130  may include a biological agent capable of increasing the likelihood of inducing ingrowth of physiological components. For example, calcitonin or other biological or non-biological agents may be used as agents to coat fixation component  130 . 
   Structural Bag 
   In some embodiments, any structure such as a bag structure or fixation member of the present invention including bag structure  100  may be formed of one or more different materials, which exhibit semi-permeable, flexible, resilient and/or elastic properties. These materials are discussed in the following paragraphs. In one example, the material of bag structure  100  is such that it is capable of being easily stretched, expanded or compressed, and then resuming its former shape or close to its former shape (U.S. patent application Ser. No. 11/201,837, incorporated herein by reference in its entirety). In one embodiment, a bag structure  100  may be formed from a woven or non-woven polymeric fiber material, such as, an aramid material (e.g., Kevlar™, Nomex™, Twaron™, etc.), a polyester fiber material, an ultra high molecular weight polyethylene fiber material, a nylon fiber material, a cellulose fiber material, a polyurethane fiber material, or a polyacrylonitrile based fiber material. In another embodiment a bag structure made of woven material may have a dome shape to the top and/or bottom part of the bag. In accordance with this embodiment, a dome of the bag can be thick and resilient in order to ease transition of the adjacent natural environment and an implant device. In some embodiments the polymeric fiber material may be woven or configured into a 2-dimensional or 3-dimensional fabric configuration. In accordance with these embodiments the weave may be a honeycomb weave. The weave pore size may vary as a function of fabric density. 
   In another embodiment of the present invention, bag structure  100  may be made and/or formed from a metallic material, such as nitinol, stainless steel (e.g., heat—treated PH 17-7 stainless steel fabric) or the like. In still other embodiments, bag structure  100  may be made and/or formed from metallic fibers woven into a fabric-type material. In some embodiments, the fabric-type material may be a 2-dimensional or 3-dimensional fabric configuration. 
   In further embodiments, bag structure  100  may be made of a combination of materials. For example, one combination might be a combination of a polymeric fiber and a metallic material; e.g., an aramid material (e.g., Kevlar or the like) and a metallic material (e.g., nitinol, stainless steel). 
   In another embodiment of the present invention, bag structure  100  may be made of a semi-permeable, flexible, composite material, such as a composite of an elastomeric or hydrogel matrix material and a polymeric fiber, a metal fiber or wire, or a ceramic fiber. Examples of suitable matrix materials that may be used to form bag structure  100  include, but are not limited to, a natural or synthetic polymer matrix material, an elastomer, a flexible polyolefin polymer, an elastomeric matrix material, or a hydrogel material. 
   Discussed above are various examples of classes of materials that may be used to form bag structure  100  as well as other structures of the present invention. Other specific materials that may be used to make bag structure  100  include, but are not limited to, polyaramid fibers, such as Kevlar 49, Kevlar 149- or the like, ultra high molecular weight, highly oriented, highly crystalline polyethylene (e.g., Dyneema or Spectra 900 or Spectra 1000), polyester fibers, such as Dacron, silk fiber, elastin fiber, elastomeric materials (polyurethane or other thermoplastic elastomer), fused PTFE (Polytetrafluoroethylene), expanded PTFE of generally high tenacity fibers or other high strength woven or non-woven fibers or fabrics. It is also contemplated that any embodiment of the present invention may be accompanied by vertebrolasty to increase the strength of any weakened vertebrae including but not limited to disease, aging or injury. 
   Referring now to  FIGS. 2A ,  2 B and  2 C, one embodiment of the present invention includes an intervertebral disc prosthetic bag structure  200  that may be used for replacing all or part of a diseased, damaged or otherwise non-functional intervertebral disc. In the illustrated embodiment, bag structure  200  includes an outer body  210  and a fixation member  240  including at least one fixation member that extends exteriorly from the outer body  210 . Fixation member  240  may be optionally attached to a fixation layer  230 , and an optional interfacing layer  220  may separate fixation layer  230  from outer body  210 , an access port  150  and opening  120  for receiving, for example, an interior implant structure or material. Alternatively, fixation layer  230  and interfacing layer  220  may include one layer instead of two separate layers. 
   In accordance with some embodiments of the invention, any of the structures such as bag structure  200 , and in particular, fixation member  240  is formed of a rigid material or a flexible material as detailed previously. In other embodiments, fixation layer  230  and fixation member  240  may be attached to upper and lower surfaces  275 , 270  of a bag structure ( 265  depicts an optional bag axis). Fixation member  240  may be attached using an interfacing layer  220  such as a polymer interfacing layer as discussed. Fixation member  240  may be attached to fixation layer  230  where fixation layer  230  may be in contact with interfacing layer  220 . Alternatively, fixation member  240  may be optionally coated with an agent such as an agent to induce bone ingrowth. Examples of agents for inducing bone ingrowth might include but are not limited to cellular components such as growth factors, other proteins, matrix material, gel material or other known agents. 
   In addition, fixation member  240  may be a retainer made of a biocompatible material and may include but is not limited to a rivet, a brad, a screw, spike, dowel, pin or a combination thereof. In another example, fixation member  240  may be used to hold layers together such as fixation layer  230 , interfacing layer  220  and outer body  210  depicted in  FIG. 2C . In some embodiments, fixation member  240  may be used to place bag structure  200  in close association with vertebral bodies and reduce gaps between bag structure  200  and vertebral bodies. For example, fixation member  240  may be a rivet introduced to bag structure  200  from the inner cavity  280  of a bag structure  200  and extend exteriorly outward from the bag where one end of fixation member  240  is adapted for positioning in vertebral bodies. Fixation member  240  is capable of several functions, such as reducing separation of layers such as outer body  210 , interfacing layer  220  and fixation layer  230  as well as providing direct contact between fixation member  240  and intervertebral bone in order to increase communication between the prosthetic implant structure and vertebral bodies. 
   In some embodiments, it is contemplated that any component in the present disclosure may be made of a flexible material as discussed previously. With this in mind, the later prosthetic implant structure having fixation member  240  may have a time dependent deformation; thus, there is viscoelastic quality to the material in some of these examples. Therefore, bag structure  200  having fixation member  240  may be compressed, so that it may be implanted in an intervertebral disc space cavity using a delivery device, such as a catheter, stylet or the like. Once inserted into the intervertebral space, bag structure  200  having fixation member  240  may be released from the delivery device, so that it returns to its relaxed state. Alternatively, bag structure  200  having fixation member  240  may be placed into an intervertebral space using, for example, a pair of forceps or other known method for placement. 
   In one embodiment, fixation member  240  may be positioned on top  275  and on bottom  270  of the bag structure to increase the likelihood of contact of fixation member  240  with vertebral bodies (see  FIG. 2B . In another embodiment, fixation member  240  may be positioned on top  275  and on bottom  270  of bag structure  200  wherein fixation member  240  on the top  275  is substantially symmetrical to fixation member  240  on bottom of the bag structure as shown in  FIG. 2B . Implantation of the bag structure will be discussed in more detail below. 
   One advantage of fixation member  240  or fixation layer  230  is gross relative motion may be reduced between an implant device and vertebral endplates and reduction of this motion may increase support in transverse shear loads. In addition, device  200  is capable of being reduced in size and implanting the device may occur with less surgical trauma. 
   Surveying and Sizing 
   It is contemplated that any one of the prosthetic implant structures disclosed herein may be introduced in a similar fashion as described for bag structure  100  or may be introduced using other known methods in the art. In addition, it is contemplated herein that any known method for assessing a cavity or estimating a size needed for an implantation structure may be used for any embodiment of the present invention. In some embodiments, once the nucleus is removed in preparation for implantation of a prosthetic device, a deployment device may be used to assess the cavity condition prior to introduction of any implant structure. For example, a balloon catheter may be introduced to the cavity and filled with an agent such as a contrast solution and the area viewed with an instrument such as an X-ray, c-arm, intraoperative CT-scan or the like. A healthcare professional may view the cavity to assess whether the area is ready for the insertion of the prosthetic implant or requires additional preparation. It is contemplated that any sizing device known in the art may be used to assess the size and dimensions of an implant device needed for disc replacement. 
   In accordance with one embodiment of the present invention, once the nucleus material is removed, a delivery device (e.g., a cannula or other catheter device) may be used to introduce bag structure  100  having a fixation component  130  (see  FIGS. 1  or  3 ) into the annulus cavity. In one embodiment, bag structure  100  may be stretched and/or compressed and then attached to the delivery device so that it may be delivered through an opening in the disc annulus into the disc nucleus region. For example, in one embodiment, bag structure  100  is compressed into a cannula or onto a catheter, and then delivered into the nucleus region using a balloon catheter delivery technique, or the like. After the bag structure  100  having a fixation component  130  is delivered into the nucleus region, it is released. In some embodiments, upon release, bag structure  100  will expand to substantially its uncompressed original shape. 
   In other embodiments, a balloon device (e.g., balloon catheter device) may be used to deploy bag structure  100  within the disc nucleus region. As one skilled in the art will appreciate, during a balloon catheter delivery procedure, a balloon catheter is used to place bag structure  100  within the disc nucleus, and then a balloon is inflated within the bag structure  100 , causing the compressed bag structure to expand to its original or close to original shape. In one embodiment, bag structure  100  having a fixation component  130  may be deployed using a balloon catheter such that deploying the bag may position the fixation component of the bag near or in close proximity to the vertebral bodies. In another embodiment, deploying bag structure  100  having a fixation component  130  can position the fixation component in direct contact with the vertebral bodies. In one example, the fixation component  130  is coated by an agent such as a biological agent for example, calcitonin or the like. Once bag structure  100  is expanded, the balloon is deflated and then removed. 
   In some embodiments, an interior implant material and/or structure may be placed into a cavity  280  of any bag structure (see  FIGS. 1-4 ) such as bag structure  100  through the opening  120  so that the combination of bag structure  100  and interior implant material  410  provide a resilient disc nucleus prosthesis  400 . In some embodiments, interior implant material or structure  410  conforms to at least a portion of the interior cavity  280  of bag structure  100 , thus providing additional spinal support within the intervertebral space. In accordance with some embodiments of the invention, interior implant material or device  410  may be, for example, a hydrogel implant, a spiral implant, a biological implant, a hydratable material. the implant structure discussed below, or any other suitable disc implant material or device. In one embodiment, the interior implant material and/or device may be, for example, a sinusoidal-shaped structural device disclosed in U.S. patent application Ser. No. 11/201,837, which is incorporated herein by reference in its entirety. Further, in other embodiments, the sinusoidal-shaped structural device discussed below may be implanted or positioned within bag structure  100 . Alternatively, bag structure  100  outer body may be coated with an agent such as a polymer (e.g. polyurethane) to reduce leakage of an interior implant introduced to bag structure  100 . The implantation of this device in a bag structure will be discussed in more detail below. 
   In yet another embodiment of the present invention, an interior implant structure may include a structure capable of being fed into an opening in the bag structure such that the bag cavity may be fed the interior implant until the bag cavity is substantially filled. Then, the remaining interior implant structure is severed from the implanted portion. Then, the bag opening may be sealed to reduce escape of the interior implant. 
   Different delivery devices and/or methods may be used to insert the interior implant into the bag structure, and the delivery devices and/or methods used may differ depending on the type of implant material or structure used. After the interior implant material and/or structure is placed within bag structure  100 , opening  120  of bag structure  100  then may be sealed or closed, thus reducing extrusion of interior implant material and/or structure from within a bag structure. As one skilled in the art will appreciate, any sealing or closing process and/or device may be used to seal the bag structure, such as suturing, clamping, tying, using a single directional opening valve or the like. 
   Referring now to  FIG. 5 , a cross-sectional view of a spinal column  500  having a herniated disc or damaged disc is shown. In the illustrated embodiment, the cross-section shows a vertebrae  510 , a spinal cord  520  with nerve roots  570 , and a disc  530 , having an annulus  540  and a disc nucleus  550 . As is illustrated by location  560  in  FIG. 5 , a herniated disc occurs when disc nucleus  550  protrudes an opening or weakness in annulus  540 . The annulus or extruded nucleus may put pressure on spinal cord  520  and/or nerve roots  570 . When this occurs, one remedy is to remove the protruding disc annulus and/or nucleus and replace it with a prosthetic nucleus or total disc structure and/or material. These procedures are known in the art, and thus, will not be discussed in detail herein. 
   Referring now to  FIGS. 6A-6D , one embodiment of the present invention includes implantation for an intervertebral disc prosthesis structure where at least a portion of the disc nucleus is removed and the annulus may be cut forming an opening. This method of implantation may preserve the integrity of the annulus and may also reduce scarring typically complicating other implantation methods. Reduction in scarring may reduce the likelihood of impaired movement and pain. In addition, preserving the annulus structure may also reduce adhesion and scarring due to typical post-implantation healing and recovery, especially with respect to total disc replacement. In accordance with this embodiment of the invention and as depicted in  FIGS. 6A and 6B , cuts  620  are made in the annulus  610  to produce a movable portion  625  in the annulus  610  such as a flap, hatch, door, double-door and the like with minimal or no removal of annulus tissue. In accordance with this embodiment, the movable annulus portion  625  may be adapted for use in any procedure that requires access to a disc region. In one embodiment, an opening  640  accessed by opening movable annulus portion  625  may be of a predetermined size and/or a size based on dimensions for implantation device  630 . The prosthetic structure and/or material  630  may be placed within the annulus  610  where the nucleus material was removed, as shown in  FIG. 6C , and annulus  610  may be sealed  650 , as shown in  FIG. 6D , by any means known in the art such as suturing, stapling, tacking with a biocompatible adhesive agent or the like. 
   Referring now to  FIGS. 7 ,  8 A and  8 B, one embodiment of the present invention includes removal of a substantial portion of a disc annulus prior to implantation of an intervertebral disc prosthetic structure  700 . Implant structure  700  includes an upper and lower substantially flat surface  710 , an interior surface  730 , an exterior surface  740  and an access port  720 . Implant structure  700  may be a thick-walled textile structure of a single layer of material or a combination of several layers of material. In accordance with one embodiment of the invention, implant structure  700  may be made of a series of flat donut-shaped rings laying one on top of the other for example using fabrics such as Offray Specialty fabrics, honeycomb weave fabrics or other 2 or 3 dimensional fabrics. It is contemplated herein that any fabric used to make implant structure  700  may be made of any resilient material that permits springing, cushioning, bending, and rotation. 
   In one embodiment, implant structure  700  may be combined with a membrane-like component  910  to provide an intervertebral implant  900  depicted in  FIG. 9 , where implant structure  700  provides a flat surface  710  for engaging endplates such as vertebral endplates where the endplates are in close proximity to the flat surface  710  of implant  900 . In addition, implant structure  700  may be used to anchor the membrane-like component  910  such as any membrane material identified for use on bag structure  100 . Optionally, once an implant  900  with flat surface  710  and membrane component  910  is introduced to the intervertebral space, inner cavity  730  may be filled via access port  720  with, for example, a polymer such as an elastomer, hydrogel, in situ curable hydrogel or the like. It is contemplated herein that in some embodiments membrane  910  is expandable to substantially conform to the disc space. This expansion may occur on the upper and lower surfaces of membrane  910  of intervertebral implant  900 . In another embodiment, flat surface  710  may be bonded with a metal fiber such as trabecular metal to increase fixation of intervertebral implant  900  with intervertebral bodies. 
   Referring now to  FIGS. 10A and 10B , one aspect of the present invention relates to an interior implant structure, which may act as a portion of a disc replacement prosthesis, or at least as an interior portion of a disc prosthesis structure; one embodiment of which is illustrated in  FIGS. 10A-10B  (U.S. patent application Ser. No. 11/201,837, incorporated herein by reference in its entirety). In the illustrated embodiment, interior implant structure  1000  includes one or more sinusoidal-shaped structures  1005 . In accordance with this particular embodiment of the invention, each sinusoidal-shaped structure  1005  includes a plurality of periodic portions  1010 , which are formed of a flexible, resilient, elastic material similar to the material discussed previously for bag structure  100 . As illustrated in  FIGS. 10A-10B , each periodic portion  1010  intersecting a longitudinal axis  1020  of the interior implant structure  1000  at two points,  1030   a  and  1030   b . In one embodiment, the sinusoidal-shaped structures  1005  are flexible, such that when stretched in a longitudinal direction (i.e., along axis  1020 ), the structure sufficiently flattens or otherwise reduces the amplitude of each of the periodic portions  1010 , so that it may be placed within a disc nucleus region or holding structure within the disc nucleus region (e.g., bag structure  100 , discussed above).  FIG. 10B  illustrates one embodiment of interior implant structure  1000  (i.e., sinusoidal-shaped structures) in a stretched configuration. 
   As illustrated in  FIG. 10A  and  FIG. 10B , one embodiment of the invention may have multiple sinusoidal-shaped structures  1005  positioned together, or otherwise interwoven with each other. The embodiment illustrated in  FIG. 10A and 10B  show two sinusoidal-shaped structures  1005  interwoven or otherwise joined and positioned in planes that are positioned at or near 90 degrees from one another. In other embodiments, two sinusoidal-shaped structures  1005  may be positioned in different planes that are not necessarily perpendicular to one another. In still other embodiments, more than two sinusoidal-shaped structures  1005  may be used. In another example, a sinusoidal-shaped structure may be introduced to bag structure  100  where the sinusoidal-shaped structure is loaded into the cavity until bag structure  100  is substantially filled with the interior implant and then the excess sinusoidal-shaped structure is removed. Removal of excess sinusoidal-shaped structure may include any known method in the art such as cutting off the unused portion of structure  1000 . In accordance with embodiments of the invention, sinusoidal-shaped structures  1000  may be reduced in volume and loaded onto a delivery device such as a cannula or forceps for delivery to the intervertebral space or cavity. 
   In one embodiment, interior implant structure  1000  may be inserted into a bag structure (e.g., bag structure  100 ) located in the intervertebral cavity using an external delivery device, such as a cannula, a catheter, or other suitable delivery device. In accordance with one embodiment, a delivery device may be inserted through holes  1040  in sinusoidal-shaped structures  1005 , and then the structures may be stretched along the delivery device to reduce the height or amplitude of the sinusoidal-shaped devices, as discussed above. Once the height of the structure is sufficiently reduced, it may be positioned or placed within the internal cavity  280  of bag structure  100 , for example, through opening  120  in bag structure  100 . Once inside a bag structure, interior implant structure  1000  (i.e., sinusoidal structures  1005 ) is released from the delivery device, which will allow structures  1000  to relax and return back to or near its original shape, thus filling the bag structure and at least a portion of the disc cavity regions. 
   In some embodiments, a coating agent may be applied to a structure (e.g., bag structure  100 ) and/or an interior implant structure (e.g., interior implant structure  1000 ). In one embodiment, the coating agent may include one or more of hydrogel, a curable biomaterial that changes states once introduced to the intervertebral disc region (e.g., by chemical or heat promotion), elastomers (e.g., thermoset and thermoplastic), polyolefins, therapeutic agents (e.g., anti-bacterial or anti-fungal agents or biological agents). Biological agents may include, for example, tissue extracts, cells (e.g., bone derived cells), growth factors (e.g., platelet derived growth factor (PDGF)), proteins (e.g., the hormone calcitonin) or genes (e.g., nerve growth or bone growth promoting genes). 
   Referring now to  FIG. 11 , one embodiment of the present invention includes removal of a portion of a disc annulus prior to implantation of an intervertebral disc nucleus prosthetic structure  1100  that may be used for replacing part of a diseased, damaged or otherwise non-functional intervertebral disc nucleus. Implant structure  1100  includes a flange structure  1140 , optional holes  1130  in the flange, a bag structure  1120  with an optional fixation component  1110 , and an access port  1150 . In accordance with one embodiment, implant structure  1100  may be combined with any known interior implant structure for example a sinusoidal-shaped implant structure, a hydrogel, and/or a hydratable material (e.g., a hydratable hydrogel material). 
   Referring now to  FIG. 12 , one embodiment of the present invention includes implantation for an intervertebral disc prosthesis structure. In accordance with this embodiment of the invention, implantation device  1100  having flange  1140  may be introduced to cavity  1220  and optionally anchored to vertebral bodies using, for example, rivets through flange holes  1130 . In another embodiment, flange holes  1130  may be used to increase attachment of physiological components to implantation device  1100  such as bone regeneration components. In accordance with this embodiment, bone may grow into and around flange hole  1130  thus inducing attachment of implantation device  1100  to the vertebral disc. To further induce the ingrowth of bone, flange hole openings may be coated with a biological agent to recruit physiological components to flange  1140 . Alternatively, flange  1140  may adhere to vertebral bodies using any known adhesive such as a biocompatible adhesive. In another embodiment, implantation device  1100  may be made of any bag structure material previously discussed such as a elastic or viscoelastic material. In accordance with this embodiment, implantation device  1100  may be reduced in size for introduction to a cavity for example by stretching or folding flange  1140  onto the remaining components of implantation device  1100  and loading it onto a delivery device for introduction to a cavity and then resume its original shape or near original shape once released from the delivery device. In addition if required, flange  1140  may be unfolded and aligned exterior to the nucleus region using a device such as forceps. Once implantation device  1100  is within a cavity, any known interior implant material may be added. Optionally, an interior implant material such as sinusoidal material  1000  may be introduced within an interior cavity of implant device. Implant device  1100  may be sealed by any means known in the art such as suturing, tacking with a biocompatible adhesive agent or the like. 
   The foregoing discussion of the invention has been presented for purposes of illustration and description. It is not intended to limit the invention to the form or forms disclosed herein. Although the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights, which include alternative embodiments, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.