Abstract:
A implant is provided for placement in a space between boney structures. The implant may comprise a flexible section. The flexible section may be either the anterior side or the posterior side of the implant or both, among other sides. The flexible section or sections may comprise one or more orifices, cavities, or low modulus of elasticity materials among others. The flexible section or sections may facilitate a wider range of motion than otherwise possible for a spinal column comprising a Lumbar Interbody Fusion (LIF) device. Additionally, the anterior side comprising a flexible section may have a different modulus of elasticity than the posterior side comprising a flexible section. The difference may facilitate a wider range of responses from the implant to movement generated forces in at least two directions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application relates to, and claims the benefit of the filing date of, co-pending U.S. Provisional Patent Application Ser. No. 60/785,195 entitled “FLEXIBLE CAGE SPINAL IMPLANT,” filed Mar. 23, 2006, the entire contents of which are incorporated herein by reference for all purposes. This application also relates to co-pending U.S. Provisional Application 60/825,089, entitled “OFFSET RADIUS LORDOSIS,” filed Sep. 8, 2006, and to U.S. patent application Ser. No. ______, entitled “INSTRUMENTS FOR DELIVERING SPINAL IMPLANTS” filed concurrently herewith, and to U.S. application Ser. No. 11/303,138, entitled “THREE COLUMN SUPPORT DYNAMIC STABILIZATION SYSTEM AND METHOD OF USE,” filed Dec. 16, 2005, the contents of which are incorporated herein by reference for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    This disclosure relates to systems and methods for treating diseases of human spines, and more particularly, to interbody implant devices. 
         [0003]    The human spine is a complex structure designed to achieve a myriad of tasks, many of them of a complex kinematic nature. The spinal vertebrae allow the spine to flex in three axes of movement relative to the portion of the spine in motion. These axes include the horizontal (e.g., bending either forward/anterior or aft/posterior), roll (e.g., lateral bending to either left or right side) and rotation (e.g., twisting of the shoulders relative to the pelvis). 
         [0004]    The inter-vertebral spacing (between neighboring vertebrae) in a healthy spine is maintained by a compressible and somewhat elastic disc. The disc serves to allow the spine to move about the various axes of rotation and through the various arcs and movements required for normal mobility. The elasticity of the disc maintains spacing between the vertebrae during flexion and lateral bending of the spine, allowing room or clearance during the compressive movement of neighboring vertebrae. In addition, the disc enables relative rotation about the vertical axis of the neighboring vertebrae, allowing for the twisting of the shoulders relative to the hips and pelvis. Clearance between neighboring vertebrae maintained by a healthy disc is also important to enable the nerves from the spinal cord to extend out of the spine, between neighboring vertebrae, without being squeezed or impinged by the vertebrae. 
         [0005]    In situations (e.g., based upon injury or otherwise) where a disc is not functioning properly, the inter-vertebral disc tends to over compress. With the over compression, pressure may be exerted on nerves extending from the spinal cord due to this reduced inter-vertebral spacing. Various other types of nerve problems may also be experienced in the spine, such as exiting nerve root compression in neural foramen, passing nerve root compression, and enervated annulus (i.e., where nerves grow into a cracked/compromised annulus, causing pain every time the disc/annulus is compressed), as examples. Many medical procedures have been devised to alleviate such nerve compression and the pain that results from the nerve pressure. Many of these procedures revolve around attempts to prevent the vertebrae from moving too close to each other by surgically removing an improperly functioning disc and replacing the disc with a lumbar interbody fusion (“LIF”) device. Although prior interbody devices, including LIF cage devices, may be effective at improving patient condition, these LIF cage devices may not provide the range of flexibility and support of a properly functioning disc. 
         [0006]    It would be desirable to improve the flexibility of the LIF cage devices, while maintaining the high strength, durability and reliability, of the LIF cage device. A flexible LIF cage device may better enable a patient move about the various axes of rotation and through the various arcs and movements required for a normal range of mobility. 
       SUMMARY 
       [0007]    An embodiment of the present invention may comprise a flexibility enabling member on a section of an implant. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    For a more complete understanding of this disclosure reference is now made to the following Detailed Description taken in conjunction with the accompanying drawings, in which: 
           [0009]      FIG. 1  illustrates an oblique view of an embodiment of a flexible spinal implant designed to be inserted into an intervertebral space; 
           [0010]      FIG. 2  illustrates a top view of the flexible spinal implant; 
           [0011]      FIG. 3  illustrates an anterior view of the flexible spinal implant; 
           [0012]      FIG. 4  illustrates a midline cross-sectional view of the flexible spinal implant; 
           [0013]      FIG. 5  illustrates an anterior view of the flexible spinal implant, wherein a force is applied to the top portion of the implant; 
           [0014]      FIG. 6A  illustrates a side view of the flexible spinal implant, wherein a force is applied to the anterior portion of the implant; 
           [0015]      FIG. 6B  illustrates an alternative side view of the flexible spinal implant, wherein a force is applied to the posterior portion of the implant; 
           [0016]      FIG. 7  illustrates an oblique view of the flexible spinal implant, wherein openings of the implant may be pushed out; 
           [0017]      FIGS. 8A-D  illustrate anterior views of some of the various embodiments of the flexible spinal implant; 
           [0018]      FIG. 9  illustrates a sagittal view of the flexible spinal implant, wherein the implant is located between two adjacent vertebrae; 
           [0019]      FIG. 10  illustrates an oblique view of a flexible spinal implant, wherein the implant is being injected with a material; 
           [0020]      FIG. 11A  illustrates a sagittal view of the flexible spinal implant, wherein the implant comprises a port for injecting a material; and 
           [0021]      FIG. 11B  illustrates a midline section view of the flexible spinal implant, wherein the implant comprises a port for injecting a material. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the embodiments described in this disclosure may be practiced without such specific details. In other instances, well-known elements may have been illustrated in schematic or block diagram form in order not to obscure the present invention in unnecessary detail. Additionally, for the most part, details concerning well known features and elements may have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the understanding of persons of ordinary skill in the relevant art. 
       An Illustrative Embodiment 
       [0023]    Turning now to the drawings,  FIG. 1  shows an oblique view of an illustrative embodiment of a flexible spinal implant  100  configured according to at least a portion of the subject matter of the present invention and designed to be inserted into an intervertebral space. The flexible spinal implant  100  may have multiple flexural components  102  provided in an anterior surface of the implant  100 . The flexible spinal implant  100  may also have multiple flexural components  104  provided in a posterior surface of the implant  100 . These flexural components  102  and  104  may comprise empty space (e.g., voids, apertures, cavities, or no material) or they may be filled with a material having a lower modulus of elasticity than a surrounding portion of the implant  100 . The flexural components  104  may be of a similar configuration to the flexural components  102 , or they may be different. Additionally, all of the flexural components  102 ,  104  of an anterior or a posterior surface may comprise the same or different configurations. Although, multiple flexural components  102 ,  104  are shown in this illustrative embodiment of the present invention, a single flexural component  102 ,  104  may exist on an anterior and/or a posterior surface. 
         [0024]    Multiple protrusions  106  may be located on the top surface and/or the bottom surface of the implant  100 . In certain embodiments, these protrusions  106  may help to prevent the implant  100  from substantially moving within the intervertebral space. Although the protrusions  106  may be shown in  FIG. 1  as being rectangular shaped, the protrusions  106  may not be limited to this configuration. Any geometric configuration may be used. In addition, an undulating surface may also provide the benefit of fixing the implant  100  in place without necessarily being a distinct protrusion. A single protrusion  106  on the top surface and/or the bottom surface of the implant  100  may also be used. The protrusions  106  may restrain the implant in a relatively fixed location by engaging the opposing surfaces of the endplates of adjacent vertebrae. 
         [0025]    As shown in  FIG. 1 , in some embodiments the endpoints  108  of the anterior flexural components  102  may extend to the side surfaces of the implant  100 . The endpoints  110  of the posterior flexural components  104  may be limited to the posterior surface of the implant  100 . Accordingly, in multiple embodiments the anterior flexural components  102  and the posterior flexural components  104  may have a wide range of lengths, widths, and positions. These flexural components  102  and  104  may be configured to alter, reposition, or increase the flexibility of the spinal implant  100 . 
         [0026]    With multiple flexural components  102  on the anterior surface of the implant  100 , the anterior surface of the implant  100  may exhibit an increased ability to resiliently deform when a force is applied to the anterior portion of the implant  100 . Similarly, with multiple flexural components on the posterior surface of the implant  100 , the posterior surface of the implant  100  may also exhibit an increased ability to resiliently deform when a force is applied to the posterior portion of the implant  100 . Accordingly, the implant  100  may be able to provide support within the intervertebral space and also provide a range of flexibility when adjacent vertebrae exert a force on the implant  100 . In certain embodiments, these flexural components  102  and  104  may provide flexibility through less material (e.g., through the use of a cavity, orifice, or a variable thickness of material), which may produce a lower modulus of elasticity, or through a lower modulus material (e.g., through the use of different heat treatments or material processing, or the substitution or addition of a separate material). 
         [0027]    The implant  100  may be manufactured from a variety of biocompatible materials. For example, the implant  100  may be made from biocompatible plastics or metals such as PEEK(poly-ether-ether-ketone), carbon filled PEEK, titanium, or stainless steel, among others. The implant  100  may preferably comprise a sufficient level of strength to at least partially replace a supporting function of an intervertebral disc such that adjacent vertebrae may maintain a desired minimum amount of spacing between opposing surfaces. In some embodiments, the implant  100  may be made of metal, such as cobalt chrome, or titanium. In other embodiments, the implant  100  may be made of ceramic materials or a combination of both metal and ceramic materials, such as oxidized zirconium. 
         [0028]    Turning now to  FIG. 2 , this figure illustrates a top view of the flexible spinal implant  100 . Multiple protrusions  106  may be located on the top portion of the implant  100 . As more easily seen in  FIG. 2 , in some embodiments the length of the anterior flexural components, which may be defined by the endpoints  108 , may be longer than the length of the posterior flexural components, which may be defined by the endpoints  110 . In this view, the endpoints  108  may be seen as extending to the sides of the implant  100  while the endpoints  110  may be confined to the posterior side surface of the implant  100 . However, the locations and separations of the various endpoints  108 , and  110  may not be limited to this illustrative embodiment. 
         [0029]    The implant  100  may be a substantially oval-shape with a relatively empty center. This oval-shape of the implant  100  may correspond to the shape of the intervertebral disc. This empty center of the implant  100  may be filled with cadaveric bone, autologous bone, bone slurry, bone morphogenic protein (“BMP”) or a similar material. These types of materials may help with tissue growth within the intervertebral space. In some embodiments, openings created by the openings  102  and  104  may further help with tissue growth by allowing the material to seep into the intervertebral space. The illustrative embodiment is shown with a relatively consistent wall thickness. However, depending upon the flexibility configuration, the wall thickness may vary around the perimeter of the implant  100 . 
         [0030]    Referring now to  FIG. 3 , this figure illustrates an anterior view of the flexible spinal implant  100 . As stated previously, in certain embodiments the anterior openings  102  may extend further in length than the posterior openings  104  (the posterior openings  104  are seen through the anterior openings  102  in this figure). Accordingly, from an anterior view the endpoints  110  of the posterior openings  104  may be visible because the endpoints  108  of the anterior openings  102  may extend to the side portions of the implant  100 . The anterior openings  102  are shown as being approximately the same number and overall design as the posterior openings  104  as an example of one amongst many embodiments. The protrusions  106  are shown as existing on both the top surface and the bottom surface of the implant  100  in this representation of an exemplary embodiment. 
         [0031]    Turning now to  FIG. 4 , this figure shows a midline cross-sectional sagittal view of the flexible spinal implant  100 . As seen in this drawing, in certain embodiments the anterior openings  102  may extend to the side portions of the implant  100 , while the posterior openings  104  may not extend to the side portions of the implant  100 . In addition, the top and bottom surfaces may be substantially parallel in the absence of an applied force to the implant  100 . 
         [0032]    However, some embodiments of the implant (not shown) may be configured such that the top or bottom surfaces may be at an angle to each other in an unloaded condition. These implants may help to restore or recreate a lordosis angle (or other angle) of a human spine. In addition, both of the top and bottom surfaces of the implant may be at an angle relative to a horizontal midline of the implant in an unloaded condition. Alternatively, in certain embodiments (not shown), the top and/or bottom surfaces may be formed from a curved or compound curved surface, instead of the relatively straight line configurations shown in the figure. These implants may also help to restore or recreate a lordosis angle (or other angle) of a human spine. In addition, the contoured top and bottom surfaces (i.e., superior and inferior surfaces) may conform more closely to the concave end plates of the adjacent vertebra. More particularly, the compound curved surfaces may be created by offsetting the radii used to machine the top and bottom (i.e., bearing) surfaces of the implant. 
         [0033]    Further, the cross-sections are shown in  FIG. 4  with relatively straight line configurations to aid in simplifying the figures. Although an embodiment of the current invention may be formed as shown, the implant may not be limited to such a configuration. The cross-sections may comprise curved, angular, arcuate, and other configurations able to alter the flexibility of the implant  100 . Additionally, all of the anterior openings  102  and the posterior openings  104  are shown as establishing communication between the interior and the exterior of the implant  100 . As stated previously, in some embodiments, the anterior openings  102  and/or the posterior openings  104  may extend only partially through the walls of the implant  100 . 
         [0034]    Referring now to  FIG. 5 , this figure illustrates an anterior view of the flexible spinal implant  100  (shown in broken lines), wherein a force  602  is applied to the top portion of the implant  100 . The force  602  applied to the top portion of the implant  100  may cause the implant  100  to deform or compress into a form of an implant  600  (actual deformation may be exaggerated in this figure for the purposes of illustration). As shown in  FIG. 5 , the anterior openings  102  may also compress, enabling the top surface of the implant  600  to move closer to the bottom surface of the implant  600 . The deformation of the implant  600  may enable a larger range of motion for a spinal column in which the implant  600  has been inserted. The deformation is shown as being larger in the central section than at the sides of the implant  600 . This may be due in part to the increased stiffness of the sides of the implant  600  due to a relatively smaller quantity of openings. Although the posterior openings  104  ( FIG. 3 ) may not be visible in  FIG. 5 , these openings  104  may exhibit a similar type of compression in response to a force applied to the implant  100 . 
         [0035]    Turning now to  FIG. 6A , this figure shows a side view of a spinal implant  700  in which a force  706  has been applied to an anterior portion of the implant  700 . When a force  706  is applied to an implant (e.g., such as illustrated in  FIG. 4 ), the anterior openings  102  may compress as described with reference to  FIG. 5 . In addition, since the force  706  may be applied primarily to the anterior portion of the implant  700 , the posterior openings  104  may expand. This corresponding behavior between the openings  102  and the openings  104  may be attributed at least in part to the additional flexibility provided by the openings  102  and the openings  104  (the deformation may be exaggerated for the purposes of illustration). 
         [0036]    Accordingly, an area comprising the anterior openings  102  may be defined as a first flex-zone  708  of the implant  700 , while an area comprising the posterior openings  104  may be defined as a second flex-zone  712  of the implant  700 . The first flex-zone  708  may flexibly contract while the second flex-zone  712  may flexibly expand. However, in the event of a relatively uniform force applied to the top surface of the implant  700 , both the first flex-zone  708  and the second flex-zone  712  may be flexibly contracted or expanded, to either the same or differing degrees, depending upon the quantities and configurations of the anterior openings  102  and the posterior openings  104 . 
         [0037]    The middle portion of the implant  700 , which may comprise the side walls, may be defined as a low-flex-zone  710  of the implant  700 . The low-flex-zone  710  may provide a more consistent level of support for two adjacent vertebrae, while the flex-zones  708  and  712  may provide additional flexibility. This additional flexibility may provide an additional range of motion with respect to the two adjacent vertebrae. The low-flex-zone  710  may help to prevent excessive vertical compression and consequential damage to nerve endings passing between the two adjacent vertebrae. The relatively stronger low-flex-zone  710  may also provide a more stable platform for the flex-zones  708  and  712 . 
         [0038]    Referring now to  FIG. 6B , this figure illustrates an alternative side view of a flexible spinal implant  750  in which a force  714  has been applied to a posterior portion of the implant  750 . When a force  714  is applied to an implant (e.g., such as illustrated in  FIG. 4 ), the posterior openings  104  may contract and the anterior openings  102  may expand. As stated previously, the area comprising the anterior openings  102  and the area comprising the posterior openings  104  may be described as the flex-zones  708  and  712 , respectively. The middle portion of the implant  750 , which may comprise the side walls, may be described as the low-flex-zone  710  of the implant  750 . 
         [0039]    As shown in  FIGS. 6A and 6B , there may be at least two degrees of motion for an implant  700 ,  750  depending upon the direction and location of the applied force. The motion illustrated in an embodiment of the present invention may allow for more natural movement of a spinal column and may begin to replace at least a portion of the functionality of a collapsed intervertebral disc. Additionally, the openings  102  and  104  may function to control motion during both expansion and contraction of an implant  700 ,  750 . 
         [0040]    Turning now to  FIG. 7 , this figure shows an oblique view of an embodiment of a flexible spinal implant  800  in which the openings  102  of the implant  800  may be pushed out or removed. In certain embodiments, the implant  800  may have one or more removable members  105  retained within the implant  800  through the use of perforated dividers, interlocking features, friction forces, threaded fasteners, and adhesive forces, among others. The removable members  105  may be detached in response to a force  802  applied to the anterior or posterior portion of the implant  800 . Accordingly, a tool  804  may be utilized to apply a force  802  to the implant  800  and produce an opening  102 , by detaching the removable members. 
         [0041]    This feature may enable a physician to adjust the flexibility of the anterior or posterior portion of a standard or common implant  800  to be adapted to the specific needs of a patient or a specific requirements of a portion of a patient&#39;s spine. The removable portions  105  may be removed prior to insertion of the implant  800  within a patient&#39;s body. However, there may be situations in which a range of motion of a patient may be adjusted via the removable members  105  after insertion. Additionally, the implant  800  is shown as configured with removable members  105 . However, the flexibility of the implant  800  may be also be adjusted through the insertion of members with appropriate degrees of flexibility into openings  102 . In some embodiments, the distraction height that the implant  800  provides may be increased by placing appropriate inserts into the openings  102 . Consequently, the flexibility of a portion of a standard or common implant  800  may be increased or decreased (i.e., modified) through the removal of removable members  105  and/or insertion of other inserts into the openings  102 . 
         [0042]    Referring now to  FIG. 8A , this figure illustrates an anterior view of an embodiment of the flexible spinal implant  902 . In one example amongst many of an embodiment, the implant  902  may comprise a single opening  904 . The opening  904  for example, may be irregularly shaped, symmetrical, or asymmetrical, in order to provide additional flexibility to the anterior portion (for example) of the implant  902 . The overall design configuration for the opening  904  may be determined based upon results from finite element analysis for example. 
         [0043]    Turning now to  FIG. 8B , this figure shows an anterior view of another alternative embodiment of the flexible spinal implant  912 . In one example of an embodiment of the present invention, the implant  912  may comprise two corresponding openings  914 . These corresponding openings  914  may provide additional flexibility to the anterior portion (for example) of the implant  912 . As seen in  FIG. 8B , the two corresponding openings  914  may be configured to create an interconnecting member  915  located there between. The interconnecting member  915  may provide an additional degree of resiliency for the anterior portion of the implant  912 . While the interconnecting member  915  may be shown as being integral to the anterior portion of the implant  912 , other resilient members such as springs, compressible material, and others may be used to provide the additional degree of resiliency. 
         [0044]    Referring now to  FIG. 8C , this figure illustrates an anterior view of another alternative embodiment of the flexible spinal implant  922 . In one illustrative embodiment, the implant  922  may comprise multiple circular or other configurations of openings  924 . As shown in this example, these cylindrical openings  924  may provide additional flexibility to the anterior portion (for example) of the implant  922 . Cylindrical openings  924  may be easily created in the anterior portion of the implant  922  through the use of drills or cores during molding for example. As with the illustrative embodiment discussed along with  FIG. 7 , the numbers, sizes, and placements, of the openings  924  may be made in a more common, generic implant according to the requirements of the patient. 
         [0045]    Turning now to  FIG. 8D , this figure shows an anterior view of an alternative embodiment of the flexible spinal implant  932 . In one example of an embodiment, the implant  932  may comprise a single oval-shaped opening  934 . The oval-shaped opening  934  may provide additional flexibility to the anterior portion (for example) of the implant  932 . A large relatively smooth opening such as the opening  934  may reduce local areas of stress concentration within the implant  932 . 
         [0046]    Additional embodiments of the anterior portion of an implant  100  are within the scope of this disclosure. This disclosure should not be limited to the embodiments shown in  FIGS. 8A-8D . In addition, the embodiments shown in  FIGS. 8A-D  and other additional alternative embodiments of openings may be applied to the posterior portion or side portions of an implant  100 . The other embodiments may be applied singly, in multiple numbers, or in combinations without limit as long as the flexibility and strength of an implant  100  are maintained at desired levels. 
         [0047]    Referring now to  FIG. 9 , this figure illustrates a sagittal view of the flexible spinal implant  100  in which the implant  100  is located between two adjacent vertebrae  1002  and  1004 . As shown in  FIG. 9 , the implant  100  may be placed in an intervertebral space. In this position, the flexible spinal implant  100  may function similarly to an intervertebral disc by providing both support and flexibility. Accordingly, anterior openings  102  and posterior openings  104  may provide an appropriate amount of flexibility to the implant  100 . 
         [0048]    Protrusions  106  may help to prevent the implant  100  from significantly moving within the intervertebral space relative to the two adjacent vertebrae  1002  and  1004 . The protrusions  106  may be located on the top and bottom surface of the implant  100  and engaged with the opposing surfaces of the two adjacent vertebrae  1002  and  1004 . 
         [0049]    In certain embodiments the implant  100  may be configured as a dynamic device, such as a partial disc replacement (PDR). The implant  100  may be used to stabilize adjacent vertebrae as the spine moves in various directions. A dynamic stabilization device may be used in conjunction with the implant  100  as part of a three column support dynamic stabilization system as is described in more detail in co-pending U.S. application Ser. No. 11/303,138, entitled “THREE COLUMN SUPPORT DYNAMIC STABILIZATION SYSTEM AND METHOD OF USE,” filed Dec. 16, 2005, and incorporated herein by reference for all purposes. 
         [0050]    Turning now to  FIG. 10 , this figure shows an oblique view of a flexible spinal implant  1110  in which the implant  1110  is being injected with a material  1106 . This material  1106  may be injected in situ. In one embodiment, the implant  1110  may have a port  1102 . An insertion tube  1104  may couple to the port  1102  such that a material  1106  may be injected into the interior of the implant  1110 . This material  1106  may be utilized to provide additional support or flexibility, or to enhance tissue growth within the intervertebral space. Accordingly, materials such as cadaveric bone, autologous bone, bone slurry, BMP, or other similar material, may enhance tissue growth within the intervertebral space. In some embodiments, a separate container or walls may be provided to contain the material within the interior of the implant  1110 . 
         [0051]    Referring now to  FIG. 11A , this figure illustrates a sagittal view of the flexible spinal implant  1110  in which the implant  1110  comprises the port  1102  for injecting the material  1106 . The port  1102  may be located in any of the anterior openings  102  and the posterior openings  104 , or the port  1102  may be located in an opening configured specifically for the port  1102 . The material  1106  may be injected into the implant  1110  via this port  1102 . The material  1106  may fill the center portion of the implant  1110  as shown in  FIG. 11A . In addition, only two ports are shown in  FIG. 10  and only one port  1102  is visible in  FIG. 11A , however, a single port or a plurality of ports  1102  may be provided in the implant  1110 . Further, although a separate port  1102  may be described for inserting the material  1106 , the material  1106  may be inserted through an existing anterior and/or posterior opening  102  and  104 . 
         [0052]    Turning now to  FIG. 11B , this figure shows a midline cross-sectional view of the flexible spinal implant  1110 , in which the implant  1110  comprises a port  1102  for injecting the material  1106 . The material  1106  may be injected into the implant  1110  via this port  1102 . The material  1106  may fill the center portion of the implant  1110  as shown in  FIG. 11B . As previously stated with regard to  FIG. 4 , in certain embodiments the anterior openings  102  may extend to the side portions of the implant  1110 , while the posterior openings  104  may not extend to the side portions of the implant  1110 . In addition, the top and bottom surfaces may be substantially parallel in the absence of an applied force to the implant  1110 . 
         [0053]    The cross-sections are shown with relatively straight line configurations for the purposes of illustration. The cross-sections may comprise curved, angular, arcuate, and other configurations able to alter the flexibility of the implant  1110 . Additionally, all of the anterior openings  102  and the posterior openings  104  are shown as establishing communication between the interior and the exterior of the implant  1110 . In some embodiments, the anterior openings  102  and/or the posterior openings  104  may extend only partially through the walls of the implant  1110 . The insertion port  1102  may establish communication between the interior and the exterior of the implant  1110 . The insertion port  1102  may further comprise corresponding engagement surfaces for locating an insertion tube  1104  ( FIG. 10 ) in addition to one way valves or devices necessary to facilitate the insertion of material  1106  into the interior of the implant  1110 . 
         [0054]    It is understood that multiple embodiments can take many forms and designs. Accordingly, several variations of these embodiments may be made without departing from the scope of this disclosure. Having thus described specific embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature. A wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure. In some instances, some features may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of embodiments.