Abstract:
An expandable intervertebral implant and tool for use in implanting same are disclosed. The tool is useful in retaining the implant in a non-expanded state throughout insert of the implant between adjacent vertebral bodies. Among other elements, the tool includes a rod, a sleeve placed over the rod, and a locking knob attached to the rod and the sleeve to fix them with respect to each other. This construct preferably aids in preventing movement of the various components of the implant, including first and second members and first and second wedges. A method of attaching inserting the implant through the use of the tool and attaching the tool to the implant are also disclosed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Surgeons are performing more and more spinal surgeries to correct different spinal defects in the hopes of reducing pain and restoring normal or close to normal movement. One area of particular interest lies in the restoration of normal spacing between adjacent vertebral bodies. Whether due to the degeneration of the intervertebral disc over time or because of an injury, a decrease in spacing between vertebral bodies can cause a myriad of problems for a patient, the least of which is pain resulting from the pinching of nerves between the bodies. Correcting this problem is often very important to returning a patient to his or her normal level of activity and/or managing the pain associated with a degenerative spinal problem. 
         [0002]    Over the years, there have been many different techniques employed in restoring the normal disc space. For instance, solid fusion devices have been implanted in many patients in the hopes of both restoring normal disc spacing and preventing further degeneration of the space by fusing the vertebral bodies to one another. Recently, there has been a trend to both restore the disc spacing and allow natural movement of the adjacent vertebral bodies with respect to one another. Nonetheless, there exist certain extreme cases of degradation of the disc space which require extreme measures in order to restore the natural spacing. 
         [0003]    Often, the decrease in spacing will be so drastic that some amount of distraction of the adjacent vertebral bodies will be required. Although this distraction is sometimes achieved through the use of various tools, the desire for faster and more efficient surgical techniques favors the elimination of superfluous surgical steps. Thus, there exists a need for an intervertebral implant which is implantable in an unexpanded state and easily expandable to restore the disc space, thereby negating the need for additional tools and the additional surgical steps of using them. 
       SUMMARY OF THE INVENTION 
       [0004]    A first aspect of the present invention is an expandable implant for implantation between two vertebral bodies. In a first embodiment of this first aspect, the implant includes a first member, the first member including a first vertebral contact surface and a first interior surface, a second member, the second member including a second vertebral contact surface and a second interior surface, the first and second interior surfaces facing towards one another, a strut attached to both the first and second members, and a wedge disposed between the first and second interior surfaces and attached to at least one of the first or second members. Preferably, in this embodiment, movement of the wedge in a first direction causes movement of at least one of the first or second members in a second direction. 
         [0005]    In other embodiments of the first aspect, the wedge may be attached to at least one of the first or second members by a deformable tether. The implant may include first and second wedges, where movement of the first and second wedges towards one another causes an increase in a distance between the first and second interior surfaces. The first and second wedges may each be attached to both of the first and second members by a deformable tether. Additionally, one of the first or second wedges may include a bulleted or rounded surface for aiding in insertion of the expandable implant between the two vertebral bodies. Further, the first wedge may include first and second angled wedge surfaces for cooperating with first and second angled interior surfaces of the first and second members respectively, the second wedge may include third and fourth angled wedge surfaces for cooperating with third and fourth angled interior surfaces of the first and second members respectively, and movement of the first and second wedges towards one another may be permitted, while movement of the first and second wedges away from one another is prevented. This may be the case because the first, second, third, and fourth wedge surfaces and the first, second, third, and fourth interior surfaces may each include teeth. The first and second members and the first and second wedges may also cooperate to define at least one aperture through the implant adapted for bone growth therethrough. 
         [0006]    A second aspect the present invention may be another expandable implant for implantation between two vertebral bodies. In one embodiment according to this second aspect, the implant may include a first member, the first member including a first vertebral contact surface and a first interior surface, a second member, the second member including a second vertebral contact surface and a second interior surface, the first and second interior surfaces facing towards one another, a strut attached to both the first and second members, and first and second wedges disposed between the first and second interior surfaces, one of the first or second wedges including a bulleted or rounded surface for aiding in insertion of the expandable implant between the two vertebral bodies. Preferably, in this embodiment, movement of the first wedge towards the second wedge causes an increase in a distance between the first and second interior surfaces. 
         [0007]    In other embodiments of the second aspect, each of the first and second wedges is attached to each of the first and second members by deformable tethers. The first wedge may include first and second angled wedge surfaces for cooperating with first and second angled interior surfaces of the first and second members respectively, the second wedge may include third and fourth angled wedge surfaces for cooperating with third and fourth angled interior surfaces of the first and second members respectively, and movement of the first and second wedges towards one another may be permitted, while movement of the first and second wedges away from one another is prevented. This may be the case because the first, second, third, and fourth wedge surfaces and the first, second, third, and fourth interior surfaces each include teeth. Furthermore, the first and second members and the first and second wedges may cooperate to define at least one aperture through the implant adapted for bone growth therethrough. 
         [0008]    A third aspect of the present invention may be another expandable implant for implantation between two vertebral bodies. According to one embodiment of this third aspect, the implant may include a first member, the first member including a first vertebral contact surface and a first interior surface, a second member, the second member including a second vertebral contact surface and a second interior surface, the first and second interior surfaces facing towards one another, a strut attached to both the first and second members, and first and second wedges disposed between the first and second interior surfaces. Preferably, in this embodiment, movement of the first wedge towards the second wedge causes an increase in a distance between the first and second interior surfaces, and at least one of the first and second wedges is prevented from torsionally moving with respect to the first and second members. 
         [0009]    In other embodiments of the third aspect, each of the first and second wedges may be attached to each of the first and second members by deformable tethers. The first wedge may include first and second angled wedge surfaces for cooperating with first and second angled interior surfaces of the first and second members respectively, the second wedge may include third and fourth angled wedge surfaces for cooperating with third and fourth angled interior surfaces of the first and second members respectively, and movement of the first and second wedges towards one another may be permitted, while movement of the first and second wedges away from one another is prevented. This may be the case because the first, second, third, and fourth wedge surfaces and the first, second, third, and fourth interior surfaces may each include teeth. Further, the first and second members and the first and second wedges may cooperate to define at least one aperture through the implant adapted for bone growth therethrough. Still further, the first and second members may include either a depression or a protuberance, and the first and second wedges may include the other of a depression or a protuberance. The first and second members may include a tongue, a pin, or an elongate projection, and the first and second wedges may include either a groove or a channel. 
         [0010]    A fourth aspect of the present invention is another expandable implant for implantation between two vertebral bodies. One embodiment of this fourth aspect includes a first member, the first member including a first vertebral contact surface and a first interior surface having a first and third angled interior surfaces, a second member, the second member including a second vertebral contact surface and a second interior surface having second and fourth angled interior surfaces, the first and second interior surfaces facing towards one another, a strut attached to both the first and second members, a first wedge disposed between the first and second interior surfaces, the first wedge including first and second angled wedge surfaces for cooperating with the first and second angled interior surfaces of the first and second members respectively, and a second wedge disposed between the first and second interior surfaces, the second wedge including third and fourth angled wedge surfaces for cooperating with the third and fourth angled interior surface of the first and second members respectively. Preferably, in this embodiment, movement of the first wedge towards the second wedge causes an increase in a distance between the first and second interior surfaces, and movement of the first and second wedges towards one another may be permitted, while movement of the first and second wedges away from one another is prevented. 
         [0011]    In other embodiments of the fourth aspect, the first, second, third, and fourth wedge surfaces and the first, second, third, and fourth interior surfaces may each include teeth. Furthermore, the first and second members and the first and second wedges may cooperate to define at least one aperture through the implant adapted for bone growth therethrough. 
         [0012]    A fifth aspect of the present invention is yet another expandable implant for implantation between two vertebral bodies. In one embodiment of this fifth aspect, the implant includes a first member, the first member including a first vertebral contact surface and a first interior surface having a first and third angled interior surfaces, a second member, the second member including a second vertebral contact surface and a second interior surface having second and fourth angled interior surfaces, the first and second interior surfaces facing towards one another, a plurality of struts attached to both the first and second members, a first wedge disposed between the first and second interior surfaces, the first wedge including first and second angled wedge surfaces for cooperating with the first and second angled interior surfaces of the first and second members respectively, a first tether connecting the first wedge to one of the first or second members, a second wedge disposed between the first and second interior surfaces, the second wedge including third and fourth angled wedge surfaces for cooperating with the third and fourth angled interior surface of the first and second members respectively, and a first tether connecting the first wedge to one of the first or second members. Preferably, in this embodiment, movement of the first wedge towards the second wedge causes an increase in a distance between the first and second interior surfaces, and the first, second, third, and fourth wedge surfaces and the first, second, third, and fourth interior surfaces each include teeth. In another embodiment, one of the first or second wedges may include a bulleted or rounded surface for aiding in insertion of the expandable implant between the two vertebral bodies. 
         [0013]    A sixth aspect of the present invention is a method of implanting an expandable implant between two vertebral bodies. In a first embodiment of this sixth aspect, the method includes the steps of inserting the expandable implant between two vertebral bodies, the implant having a first member, a second member, and a wedge disposed between the first and second members and attached to at least one of the first or second members. The method also includes the step of moving the wedge in a first direction so as to cause movement of the first and second members in a second direction. Preferably, the moving step causes expansion of the first and second members which in turn causes movement of the vertebral bodies away from one another. 
         [0014]    In other embodiments of the sixth aspect, the moving step may be performed through the use of a deployment tool. The inserting step may also be performed through the use of the deployment tool. In certain embodiments, the implant may further include at least one deformable strut and more than one wedge. Each wedge may be attached to at least one of the first or second members by a deformable tether, or in some cases, the wedges may be attached to both members by deformable tethers. Additionally, the implant may further include structure which allows for the movement of the at least one wedge in a first direction, but prevents movement of the wedge in an opposition direction. Furthermore, the wedge may be prevented from torsionally rotating with respect to the first and second members. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    A more complete appreciation of the subject matter of the present invention and the various advantages thereof can be realized by reference to the following detailed description in which reference is made to the accompanying drawings in which: 
           [0016]      FIG. 1  is a front perspective view of an expandable intervertebral implant according to one embodiment of the present invention in a generally unexpanded state. 
           [0017]      FIG. 2  is a rear perspective view of the expandable intervertebral implant shown in  FIG. 1 . 
           [0018]      FIG. 3  is a side perspective view of the expandable intervertebral implant shown in  FIG. 1 . 
           [0019]      FIG. 4  is a top view of the expandable intervertebral implant shown in  FIG. 1 . 
           [0020]      FIG. 5  is a side view of the expandable intervertebral implant shown in  FIG. 1 . 
           [0021]      FIG. 6  is a front perspective view of the expandable intervertebral implant shown in  FIG. 1  in a fully expanded state. 
           [0022]      FIG. 7  is a perspective view of an expandable intervertebral implant according to another embodiment of the present invention. 
           [0023]      FIG. 8  is another perspective view of the expandable intervertebral implant shown in  FIG. 7 . 
           [0024]      FIG. 9  is a side view of the expandable intervertebral implant shown in  FIG. 7  in a fully expanded state. 
           [0025]      FIG. 10  is a perspective view of an expandable intervertebral implant according to another embodiment of the present invention. 
           [0026]      FIG. 11  is another perspective view of the expandable intervertebral implant shown in  FIG. 10 . 
           [0027]      FIG. 12  is an enlarged view of a portion of the expandable intervertebral implant shown in  FIG. 10 . 
           [0028]      FIG. 13  is a perspective view of an impaction instrument for use with the expandable intervertebral implant shown in  FIG. 1 . 
           [0029]      FIG. 14  is an enlarged view of a distal portion of the impaction instrument shown in  FIG. 13 . 
           [0030]      FIG. 15  is another enlarged view of the distal end of the impaction instrument shown in  FIG. 13 . 
           [0031]      FIG. 16  is a perspective view of a portion of one end of the impaction instrument shown in  FIG. 13 , assembled with the expandable intervertebral implant shown in  FIG. 1 . 
           [0032]      FIG. 17  is a perspective view of one end of the impaction instrument shown in  FIG. 13 , fully assembled with the expandable intervertebral implant shown in  FIG. 1 . 
           [0033]      FIG. 18  is a side cross-sectional view of the assembly shown in  FIG. 17 . 
           [0034]      FIG. 19  is a perspective view of the impaction instrument shown in  FIG. 13 , fully assembled with the expandable intervertebral implant shown in  FIG. 1 . 
           [0035]      FIG. 20  is a perspective view of a deployment tool coupled with the intervertebral implant shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    Referring to the drawings, wherein like reference numerals refer to like elements,  FIGS. 1-6  depict a first embodiment expandable intervertebral implant, designated generally by reference numeral  10 . As is shown in the drawings, implant  10  includes, among other elements that will be discussed below, a first member  12 , a second member  14 , a first wedge  16 , a second wedge  18 , and a plurality of struts  20   a - d.  Implant  10  is designed so that is capable of expanding from a generally unexpanded state (shown in  FIGS. 1-5 ) to a fully expanded state (shown in  FIG. 6 ), as well as several different partial expended states therebetween. The specific details of the structure and the operation of implant  10  will be discussed further below. 
         [0037]    As is shown in  FIGS. 1-6 , first and second members  12  and  14  are generally planar plate-like elements capable of contacting and supporting a portion of vertebral bodies implant  10  is inserted between. First member  12  includes a first vertebral body contacting surface  22  and a first interior surface  24  having two first angled interior surfaces  26   a  and  26   b.  Likewise, second member includes a second vertebral body contacting surface  28  and a second interior surface  30  having two second angled interior surfaces  32   a  and  32   b.  First and second vertebral body contacting surfaces  22  and  28  may include bone engaging elements. For example, as is shown in  FIGS. 1-6 , first vertebral body contacting surface  22  includes projections  23  and second vertebral body contacting surface  28  includes projections  29 . Preferably, these projections are capable of biting into a portion of the bone of the adjacent vertebral bodies implant  10  is inserted between. Furthermore, first angled interior surfaces  26   a  and  26   b  may include teeth  27   a  and  27   b,  respectively, while second angled interior surfaces  32   a  and  32   b  may include teeth  33   a  and  33   b,  respectively. Finally, first member  12  may define a first aperture  34  and second member  14  may define a second aperture  35  (only partially shown). 
         [0038]    As is also shown in  FIGS. 1-6 , first and second wedges  16  and  18  are somewhat triangular and include surfaces capable of cooperating with the above-discussed first and second angled interior surfaces. Specifically, first wedge  16  includes first and second angled wedge surfaces  36   a  and  36   b  for cooperation with first angled interior surface  26   a  and second angled interior surface  32   a,  and second wedge  18  includes third and fourth angled wedge surfaces  38   a  and  38   b  for cooperation with first angled interior surface  26   b  and second angled interior surface  32   b.  The various wedge surfaces may include similar teeth to those discussed above in connection with first and second angled interior surfaces. For instance, as is best shown in  FIGS. 5 , first and second angled wedge surfaces  36   a  and  36   b  include teeth  37   a  and  37   b,  respectively, and third and fourth angled wedges surfaces  38   a  and  38   b  include teeth  39   a  and  39   b,  respectively. The different cooperating teeth (i.e.,  27   a  and  37   a,    27   b  and  39   a,    33   a  and  37   b,  and  33   b  and  39   b ) preferably allow for movement of first and second wedges  16  and  18  with respect to first and second members  12  and  14  in one direction, but prevent it in an opposite direction. This will be discussed further below. It is to be understood that the wedges may exhibit any shape suitable for use in expansion of implant  10 . 
         [0039]    First wedge  16  may further include an angled, bulleted, or rounded exterior surface for aiding in insertion of implant  10  between adjacent vertebrae. In the embodiment shown in  FIGS. 1-6 , first wedge  16  includes rounded exterior surfaces  40   a - d,  which provides the bulleted nature of the exterior to the element. However, it is to be understood that angled surfaces may also be employed to achieve essentially the same functionality. First wedge  16  also preferably includes a first wedge aperture  42  (best shown in  FIG. 1 ) formed therethrough and second wedge  18  preferably includes a second wedge aperture  44  (best shown in  FIG. 2 ) formed therethrough. Both of these additional elements are preferably provided for use during expansion of implant  10 , as will be discussed further below. 
         [0040]    Struts  20   a - d  are preferably deformable so as to allow for the expansion of implant  10  upon the movement of first and second members  12  and  14  away from one another. There are many different designs for such deformable struts that may be employed. For example, as is shown in  FIGS. 1-6 , struts  20   a - d  are of an s-curve shape which facilitate easy compression and expansion. In addition, struts  20   a - d  are preferably designed so that they apply tension to first and second members  12  and  14  during and after expansion of implant  10 . This encourages even deployment of the device. More particularly, each of struts  20   a - 20   d  incorporates a specific structure designed to aid in the movement in first and second members  12  and  14  away from one another. As is shown in  FIG. 5 , each of the struts (of which only struts  20   a  and  20   b  are shown in  FIG. 5 ) includes at least one curved section  102 , which is designed to be thicker than at least one middle section  104 , such that the curved section  102  will deform subsequent to the deformation of middle section  104 . Furthermore, each strut preferably includes at least one end section  106  that is joined to one of end plates  12  and  14 . This end section  106  is preferably designed in a thicker fashion, such that there is no deformation at this point at anytime during the entire expansion sequence. Thus, the specific configuration of struts  20   a - d  facilitates the even deployment of implant  10  by specifically providing a structure that allows for a predetermined and consistent expansion sequence. 
         [0041]    First and second wedges  16  and  18  are each respectively attached to both first and second members  12  and  14 . As is shown in  FIGS. 1-6 , first wedge  16  is attached to first member  12  through the use of tethers  46   a  and  46   b,  and to second member  14  through the use of tethers  46   c  and  46   d.  Likewise, second wedge  18  is attached to first member  12  through the use of tethers  48   a  and  48   b,  and to second member  14  through the use of tethers  48   c  and  48   d.  Of course, any number of tethers may be utilized in connecting the wedges to the first and second members. Tethers  46   a - d  and  48   a - d  are preferably deformable so as to allow the movement of first and second wedges  16  and  18  with respect to first and second members  12  and  14 . As is shown in the figures, the tethers may employ a shape that allows them to deform in a proper fashion upon movement of first and second wedges  16  and  18  with respect to first and second members  12  and  14 . Like struts  20   a - d,  tethers  46   a - d  and  48   a - d  incorporate a structure specifically designed to allow for an even and consistent deployment of implant  10 . Specifically, each tether includes an end section  110  (best shown in connection with the illustration of tethers  46   a,    46   c,    48   a,  and  48   c  in  FIG. 5 ) at the connection between the tether and one of first or second members  12  or  14 , which is thicker than other areas of the tether to limit deformation. In addition, this section  110  is shaped in the manner shown in order to force a thinner curved tether section  112  to deform toward either the first or second member during the initial expansion of implant  10 . This specific geometry results in the tether&#39;s initial movement to be a collapsing motion at section  110 . Furthermore, each of tethers  46   a - d  and  48   a - d  include a connection section  114  at the connection between the tether and one of first or second wedges  16  or  18 . This section, like section  110 , is thicker than section  112  to limit the amount of deformation at the coupling of the tether and the wedge. The final expanded state of implant  10  is best shown in  FIG. 6 , which illustrates the final position of the tethers. 
         [0042]    In order to be suitable for implantation into the human body, all of the elements of implant  10  are preferably biocompatible. For example, in a preferred embodiment, each of the components of implant  10  is constructed of a metal, such as titanium (commercially pure grade 2). However, other biocompatible materials may be utilized, like other titaniums, PEEK, titanium/PEEK composites, nitonol, bioresorbables, and the like. Depending upon the material utilized, certain of the components may be formed integral with or separately from one another. For example, struts  20   a - d,  in certain embodiments, may be formed integral with first and second members  12  and  14 . Of course, in other embodiments, struts  20   a - d  and first and second members  12  and  14  may be formed separately and constructed together in accordance with normal practices. For instance, these portions could be welded or otherwise fused together. 
         [0043]    Implant  10  also preferably includes certain elements which cooperate to substantially prevent torsional movement of the first and second wedges  16  and  18  with respect to first and second members  12  and  14 . Of course, such elements are not required for proper operation of the device. As is shown in  FIGS. 1-6 , first and second members  12  and  14  are provided with elongate protuberances ( 50   a - d  and  52   a - d,  respectively). These protuberances preferably extend somewhat below the angled interior surfaces of first and second members  12  and  14 , respectively. First and second wedges  16  and  18 , on the other hand, each include four channels for cooperation with the protuberances. Specifically, first wedge includes channels  54   a - d  and second wedge includes channels  56   a - d.    
         [0044]    The cooperation between the above-discussed protuberances and channels is such that movement of wedges  16  and  18  with respect to each other and first and second members  12  and  14  is not inhibited (i.e., the wedges can move in similar directions as depicted by arrows A and B of  FIG. 5 ). However, any torsional or rotational movement of the wedges with respect to the first and second members is prevented. In other words, first and second wedges  16  and  18  are prevented from going off track. This is an important feature in ensuring a consistent operation of implant  10 . 
         [0045]    In operation, movement of first wedge  16  in the direction of arrow A ( FIG. 5 ) and movement of second wedge  18  in the direction of arrow B (also  FIG. 5 ), causes first and second members  12  and  14  to move away from one another. In other words, movement of first and second wedges  16  and  18  towards one another causes the expansion of implant  10 . Movement of first and second wedges  16  and  18  can be achieved through the use of a deployment tool (discussed below). At least a portion of such a tool preferably passes through second wedge aperture  44  of second wedge  18 , through an interior of implant  10  defined by first and second members  12  and  14  and struts  20   a - d,  and into engagement with first wedge aperture  42 . In certain embodiments, first wedge aperture  42  is threaded so as to allow for threadable engagement of the tool to the first wedge. However, other connections may also be utilized. As is discussed more fully below, deployment tool preferably acts so as to apply a pushing force to second wedge  18  while at the same time applying a pulling force to first wedge  16 . This causes the necessary movement of the first and second wedges  16  and  18  towards one another. 
         [0046]    The deformable nature of tethers  46   a - d  and  48   a - d  allows them to follow along with first and second wedges  16  and  18  during their movement towards one another. So, at all times the wedges are connected to first and second members  12  and  14 , thereby preventing them from becoming dislodged from implant  10 . This is an important safety feature of the implant. Furthermore, the above-discussed teeth located on the first and second angled interior surfaces and the angled wedge surfaces allows for the movement of first and second wedges  16  and  18  in the direction of arrows A and B, respectively, but prevents opposite movement of the components. In other words, the different cooperating teeth (i.e.,  27   a  and  37   a,    27   b  and  39   a,    33   a  and  37   b,  and  33   b  and  39   b ) are designed so as to allow the first movement, but prevent the second, opposite movement. Many different teeth designs can be employed in order to achieve this functionality. 
         [0047]      FIGS. 13-19  depict an impaction instrument  310 . This instrument is preferably utilized by a surgeon or other medical professional in order to initially place the implant between two adjacent vertebral bodies. Because of the nature of a damaged intervertebral disc space (i.e., in a collapsed position), even the nonexpanded state of implant  10  may be slightly larger than the space between adjacent vertebral bodies. Thus, an impaction instrument, like instrument  310 , often must be utilized in initially placing implant  10  in position. As is shown in  FIGS. 13-19 , instrument  310  includes three separate components, a tapered rod  312 , a sleeve  314 , and a locking knob  316 . Tapered rod  312  is preferably threaded at its distal end  318  in order to couple with a portion of implant  10 . In other embodiments, different coupling mechanisms may be employed. Sleeve  314  preferably includes a pair of deformable fingers  320   a  and  320   b,  which are capable of expanding outwardly upon insertion of sleeve  314  over the tapered portion  322  of tapered rod  312 . This expanded state is best shown in  FIGS. 13-15 . 
         [0048]    In use of instrument  310 , a surgeon would first couple tapered rod  312  with implant  10 , by passing distal end  318  of the rod through aperture  44  in the wedge  18  and into contact with aperture  42  of first wedge  16 . At this time, the threadable connection can be made by simply threading distal portion into aperture  42 . The general coupling of rod  312  with implant  10  is best shown in  FIG. 16 , while  FIG. 18  depicts the threadable coupling of the distal end of rod  312  with aperture  42  of first wedge  16 . Once the position shown in  FIG. 16  is achieved, a surgeon or other medical professional then preferably slides sleeve  314  over tapered rod  12 , thereby expanding fingers  320   a  and  320   b.  This state is best shown in  FIG. 17 . As is shown in the cross sectional view of  FIG. 18 , fingers  320   a  and  320   b  contact a portion of each of first and second members  12  and  14 . In addition, as sleeve rod  314  is inserted over tapered rod  312 , a shoulder portion  324  of such is engaged with an exterior portion of second wedge  18 . At the same time, distal end  318  of rod  312  is engaged with aperture  42  of wedge  16  and a shoulder portion  325  of rod  312  is in contact with a surface of wedge  16 . In this position, locking knob  316  is then tightened down on the proximal end  326  of instrument  310 , thereby locking rod  312  and sleeve  314  in position. Implant  10  is now protected for insertion through impaction, as first and second members  12  and  14 , and wedges  16  and  18  are locked in position and cannot move with respect to each other or any other component of this assembly. A hammer or other impaction instrument can be utilized to apply a force to a back portion  328  (best shown in  FIG. 19 ) of locking knob  316  in order to push implant  10  into the intervertebral disc space. In this regard, it is to be understood that portion  328  may be provided with a coating or other material suitable to accept the shock provided by the force from a hammer or the like. 
         [0049]      FIG. 20  shows a sample deployment tool  350 . As is mentioned above, such tool includes a distal portion  352  (shown being disposed within implant  10 ) capable of passing through aperture  44  of second wedge  18  and into engagement with aperture  42  of first wedge  16 . In addition, tool  350  also includes a portion  354  capable of engagement with second wedge  18 . Upon actuation of a trigger  356 , first portion  352  and second portion  354  move toward one another, thereby pushing wedges  16  and  18  toward one another. This movement of first and second portion  352  and  354  towards one another is facilitated by an actuation mechanism  358  associated with trigger  356 . As is more fully discussed above, this movement leads to the expansion of implant  10 . Although the embodiment shown includes a first portion, which is designed to threadably connect with aperture  42 , other connections are clearly contemplated. 
         [0050]    During a surgical procedure, a surgeon would preferably insert an unexpanded implant  10  into the space between two adjacent vertebra, utilizing the above-discussed impaction instrument  310 . This space would preferably first be cleared so as to provide the space necessary to receive the implant. The angled, bulleted, or rounded exterior surface of first wedge  16  is preferably first inserted thereby aiding in the complete insertion of implant  10 . These surfaces essentially make insertion easier, and may facilitate a slight distraction of the adjacent vertebra in order to allow for acceptance of implant  10  into the space. Impaction instrument  310  preferably holds the various components of implant  10  in a locked position throughout the insertion. Once fully inserted between the adjacent vertebrae, deployment tool  350  may be engaged with implant  10 . It is to be understood that while insertion and deployments of the implant can be achieved through the use of two different tools, it is also possible to utilize a single tool for both steps. For example, a combination impaction and deployment tool (not shown) could be provided and engaged with implant  10  prior to insertion and left attached throughout deployment. 
         [0051]    Upon movement of first and second wedges  16  and  18  towards one another, first and second members  12  and  14  expand, which preferably acts to both distract the vertebral space and also dig projections  23  and  29  of the vertebral contact surfaces  22  and  28  into the vertebral end plates of the vertebra they are in contact with. As is mentioned above, the different cooperating teeth (i.e.,  27   a  and  37   a,    27   b  and  39   a,    33   a  and  37   b,  and  33   b  and  39   b ) allow for the expansion of implant  10 , but prevent its contraction. Thus, once expanded, implant  10  remains in such a state without the addition of any further components. Nonetheless, one or more locking components could be utilized to ensure that implant  10  remains in the expanded state. 
         [0052]    It is to be understood that the above brief discussion of the surgical procedure associated with the present invention is merely exemplary, and more, less, or different steps may be performed. Moreover, it is to be understood that more than one implant  10  may be inserted and deployed between adjacent vertebrae. Depending upon the overall size of the implant (which may widely vary), more than one implant may be required in order to properly support the disc space. With the implant(s) in place and deployed, the disc space is preferably restored to at or near its original height. Bone growth may preferably occur through apertures  34  and  36  of the first and second members  12  and  14 , respectively. It is noted that first and second wedges  12  and  14  may include similar apertures or voids which ensure an open passage through implant  10  upon full expansion. In the expanded state, the interior of implant  10  can be packed with bone morphonogenic proteins or other bone growth inducing substances in order to encourage this bone growth from one adjacent vertebra to the other. 
         [0053]      FIGS. 7-9  depict a second embodiment implant  110 . Essentially, implant  110  is substantially similar to implant  10  save for the inclusion of different torsion inhibiting elements. Because of the similarity of implant  110  with implant  10 , similar or identical elements will be referred to with like reference numerals within the 100-series of numbers. For example, implant  110  includes first and second members  112  and  114  which are expandable upon movement of first and second wedges  114  and  116  towards one another. However, in the embodiment shown in  FIGS. 7-9 , first and second members  112  and  114  are provided with apertures ( 150   a - d  and  152   a - d,  respectively) which are capable of receiving protuberances (not shown). For example, these apertures may receive pins, screws, or plugs which extend somewhat below the angled interior surfaces of first and second members  112  and  114 , respectively. First and second wedges  116  and  118 , on the other hand, each include four channels for cooperation with the protuberances. Specifically, first wedge includes channels  154   a - d  and second wedge includes channels  156   a - d.    
         [0054]    The cooperation between the protuberances and channels is like that that similar elements of implant  10  such that movement of wedges  116  and  118  with respect to each other and first and second members  112  and  114  is not inhibited. However, any torsional or rotational movement of the wedges with respect to the first and second members is prevented. In other words, first and second wedges  116  and  118  are prevented from going off track. 
         [0055]      FIGS. 10-12  depict yet another embodiment implant  210 . Like, implant  110 , implant  210  is similar to implant  10 , save for the inclusion of different torsion inhibiting elements. Once again, like elements in implant  210  will be referred to within the 200-series of numbers. Instead of including a series of channels and protuberances, the torsion inhibiting elements of implant  210  include a tongue and groove cooperation between its first and second members  212  and  214  and its first and second wedges  216  and  218 . Specifically, first wedge  216  is provided with a first tongue  250   a  for cooperation with a first groove  252   a  of the first member, and a second tongue  250   b  for cooperation with a second groove  252   b  of the first member. Likewise, second wedge  218  is provided with a first tongue  250   c  for cooperation with a first groove  252   c  of the first member, and a second tongue  250   d  for cooperation with a second groove  252   d  of the second member. These elements cooperate in order to provide a nearly identical function to that of the torsion inhibiting elements discussed above in connection with implant  110 . It is to be understood that each of the above discussed torsion inhibiting elements may vary. For instance, the specific shapes of the elements can widely vary. Moreover, the inclusion of certain elements on certain components may be swapped. For example, implant  210  may include wedges employing grooves and first and second members employing tongues. 
         [0056]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.