Abstract:
An expandable implant system is disclosed in which the system comprises an implant with: (1) top and bottom plates, (2) ramp surfaces formed on inner surfaces of the plates, and (3) an expansion member situated between the plates. An actuator also forms part of the system, the actuator being removable from between the top and bottom plates after implantation of the implant. The expansion member has a set of angled surfaces for mating with the ramp surfaces of the plates and, upon movement of the expansion member along a longitudinal axis of the implant, the top and bottom plates expand from a first dimension to a second greater dimension. The top and bottom plates are also securable at varying angles to one another depending on the amount of movement of the expansion member along the ramp surfaces.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 61/775,909, filed Mar. 11, 2013, the disclosure of which is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention(s) relates to expandable implants and tools for the insertion of such implants. More particularly, the invention(s) pertains to an expandable spinal implant having opposed plates, which are expandable via the interaction between a wedge member and ramped surfaces included on the plates. An insertion instrument used for implantation of the implant, and methods of utilizing the same, are also disclosed. 
         [0003]    Common spinal maladies, such as degeneration of an intervertebral disc of the spine (commonly referred to as Degenerative Disc Disease), spondylosis, spinal stenosis, disc herniation, retrolisthesis, discogenic back pain, or other like conditions may result in substantial pain and discomfort for a patient. Frequently, conditions of this type are treated through surgical intervention, which may include replacing or removing a portion or all of the affected disc(s) and fusing the associated vertebrae through the use of an implant or other like device. In particular applications, adjacent vertebral bodies may be fused via an implant, through screw arrangements, and/or by using bone graft material to secure the vertebrae in a fixed state and promote bone growth between the vertebrae. 
         [0004]    In replacing a diseased intervertebral disc(s) and effecting fusion, it may also be necessary to ensure that proper spacing is maintained between the vertebral bodies. Stated differently, once the implant or other like device is situated between adjacent vertebrae, the implant or device should adequately recreate the spacing previously maintained via the excised intervertebral disc (e.g., in its natural condition). Various expandable implants have been proposed for this purpose. As such, it is possible for a surgeon to adjust the height of particular intervertebral implants to intra-operatively tailor the implant height to match the natural spacing between vertebrae, or any desired implant height. This may reduce the number of different implants needed to accommodate the anatomical confines of different patients. 
         [0005]    Various anatomical considerations are also present when implanting an implant between adjacent vertebrae and, for example, affecting fusion. In particular, certain areas of the spine (e.g., the lumbar and cervical areas) may include vertebrae that are, in their natural state, at an angle to one another. This natural angle is created by the lordosis or inward curvature of the spine at the particular location of the spine (lumbar/cervical). Thus, due to the naturally-occurring inward curvature of the spine at certain sections, adjacent vertebrae are at an angle to one another, which may be taken into account in certain applications. 
         [0006]    Although several versions of expandable intervertebral implants are known, as detailed above, the need for an improved expandable implant remains. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    A first aspect of the present invention includes an expandable implant system comprising an implant with top and bottom plates each having a bone-contacting surface and an opposing inner surface, the inner surface of each of the top and bottom plates including a ramp surface. The system also includes an actuator situated between the inner surfaces of the top and bottom plates, the actuator being removable from between the top and bottom plates after implantation of the implant, and an expansion member removably engageable with the actuator and located between the inner surfaces of the top and bottom plates, the expansion member having angled surfaces mating with the ramp surfaces of the top and bottom plates so that, upon actuation of the actuator, the expansion member moves along a longitudinal axis of the implant to expand the top and bottom plates from a first dimension to a second greater dimension. The top and bottom plates are capable of being arranged at varying angles to one another depending on the amount of movement of the expansion member along the ramp surfaces, the angle between the top and bottom plates accommodating the natural lordosis between adjacent vertebral bodies. In one embodiment, the expansion member is also tethered to at least one of the top and bottom plates by a deformable member extending from the at least one of the top and bottom plates. At least one of the top and bottom plates may also include a relief space adapted to allow flexion of the at least one of the top and bottom plates and permit expansion of the implant from the first dimension to the second greater dimension. 
         [0008]    A second aspect of the invention comprises an expandable implant system having an implant with top and bottom plates each having a bone-contacting surface and an opposing inner surface, the inner surface of each of the top and bottom plates including a ramp surface. The system also comprises an actuator situated between the inner surfaces of the top and bottom plates, the actuator being removable from between the top and bottom plates after implantation of the implant, and an expansion member removably engageable with the actuator and located between the inner surfaces of the top and bottom plates, the expansion member having angled surfaces mating with the ramp surfaces of the top and bottom plates so that, upon actuation of the actuator, the expansion member moves along a longitudinal axis of the implant to expand the top and bottom plates from a first dimension to a second greater dimension, wherein the top and bottom plates are arranged at varying angles to one another depending on the amount of movement of the expansion member along the ramp surfaces, the angle between the top and bottom plates accommodating the natural lordosis between adjacent vertebral bodies. At least one of the top and bottom plates may also be associated with a flange having an aperture adapted to receive a fixation member, the flange extending beyond the at least one of the top and bottom plates to prevent over insertion of the implant into an intervertebral disc space. In some cases, the ramp surfaces of the top and bottom plates and the expansion member also include teeth, the teeth of the expansion member engaging successive teeth of the ramp surfaces upon movement of the expansion member along the longitudinal axis. 
         [0009]    A third aspect of the invention includes yet another expandable implant system comprising an implant with top and bottom plates each having a bone-contacting surface and an opposing inner surface, the inner surface of each of the top and bottom plates including a ramp surface. The system also comprises an actuator situated between the inner surfaces of the top and bottom plates, the actuator being removable from between the top and bottom plates after implantation of the implant, and an expansion member removably engageable with the actuator and located between the inner surfaces of the top and bottom plates, the expansion member having angled surfaces mating with the ramp surfaces of the top and bottom plates so that, upon actuation of the actuator, the expansion member moves along a longitudinal axis of the implant to expand the top and bottom plates from a first dimension to a second greater dimension, wherein the top and bottom plates are securable at varying angles to one another depending on the amount of movement of the expansion member along the ramp surfaces, the angle between the top and bottom plates accommodating the natural lordosis between adjacent vertebral bodies. In one embodiment of this third aspect, at least one of the top and bottom plates is also associated with a flange having an aperture adapted to receive a fixation member, the flange extending beyond the at least one of the top and bottom plates to prevent over insertion of the implant into an intervertebral disc space. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    A more complete appreciation of the subject matter of the present invention(s) and of 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: 
           [0011]      FIG. 1  is a perspective view of an expandable implant, according to one embodiment of the present invention. 
           [0012]      FIGS. 2-4  are side views of the steps involved in implanting the expandable implant of  FIG. 1 . 
           [0013]      FIG. 5  is a posterior view of a portion of the spine showing two (2) of the expandable implants of  FIG. 1  implanted side-by-side. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    In describing the preferred embodiments of the invention(s) illustrated and to be described with respect to the drawings, specific terminology will be used for the sake of clarity. However, the invention(s) is not intended to be limited to any specific terms used herein, and it is to be understood that each specific term includes all technical equivalents, which operate in a similar manner to accomplish a similar purpose. 
         [0015]    Referring to  FIG. 1 , an implant  10  is shown as generally having top and bottom plates  20 ,  50  with ramp surfaces  21 ,  51  thereon, and at least one expansion member  80  for engaging the ramp surfaces  21 ,  51  and expanding the implant  10  (e.g., to place the same in a lordotic state). The implant  10  may be implanted between adjacent vertebral bodies  12 ,  14 , as shown in  FIGS. 2-5 , to aid in fusion of such bodies and immobilization of the spine at the implantation site. This may help to relieve pain associated with one of the chronic degenerative spinal conditions discussed previously. 
         [0016]    In a particular embodiment, implant  10  may have top and bottom plates  20 ,  50 , each having a bone-contacting surface  22 ,  52  and an opposing inner surface  24 ,  54 . Bone-contacting surfaces  22 ,  52  may, in one embodiment, be convexly shaped and include teeth or spikes  26 ,  56  ( FIG. 2 ), or even other fixation devices, such as a keel(s), a projection member(s), or a combination of the foregoing. Teeth or spikes  26 ,  56  may aid in securing top and bottom plates  20 ,  50  to bone, as shown in  FIGS. 2-4 . Plates  20 ,  50  may also each include one or more vertical apertures (only one of which is shown in  FIG. 1  as vertical aperture  25 ) for receiving bone-graft or other bone-growth material therein. 
         [0017]    Inner surfaces  24 ,  54  of plates  20 ,  50  may face toward one another and include, in one embodiment, respective ramp surfaces  21 ,  51 . As shown in  FIG. 2 , ramp surfaces  21 ,  51  may be angled, such that a taper  28 ,  58  is formed on top and bottom plates  20 ,  50 . Further, an end  23  of implant  10  (particularly that section of implant  10  between ramp surfaces  21 ,  51 ) may remain open, allowing for flexion of plates  20 ,  50 , while an opposing end  53  of implant  10  may remain attached or closed. In other words, at end  23  (between ramp surfaces  21 ,  51 ) top and bottom plates  20 ,  50  may remain unattached, while at end  53  such plates  20 ,  50  may be attached or connected (e.g., unitary or formed of the same material). 
         [0018]    Plates  20 ,  50  of implant  10  may also be spaced from one another, as shown in  FIG. 1 , such that a cavity is formed between inner surfaces  24 ,  54 ; and extending through the cavity from top  20  to bottom  50  plate may be a series of deformable members or struts  48   a - c . In some cases, a set of struts  48   a - c  may extend through the inner cavity of implant  10  on both sides of implant  10 , as shown in detail in  FIG. 1 . In one embodiment, struts  48   a - c  may also be of the same structure and provide the same function as any of the struts disclosed in U.S. Pat. No. 8,267,939 to Cipoletti et al. (“the &#39;939 patent”) or U.S. Patent Pub. No. 2008/0183204 to Greenhalgh et al., the disclosures of which are hereby expressly incorporated by reference herein. Thus, struts  48   a - c , in one embodiment, may be generally S-shaped and may be deformable so as to allow for contraction or expansion of implant (e.g., upon movement of plates  20 ,  50  toward or away from one another). In particular, struts  48   a - c  may be designed so that they apply tension to top and bottom plates  20 ,  50  during and after expansion of implant  10 . This encourages uniform deployment of the device, and may serve to limit distraction of plates  20 ,  50  of implant  10  apart, in some cases. 
         [0019]    As shown, for example, in  FIG. 3 , struts  48   a - c  may include at least one curved section  47 , which is designed to be thicker than at least one middle section  49 , such that the curved section  47  may deform subsequent to the middle section  49 . Each strut  48   a - c  may also include at least one end section  45  that is joined to one of plates  20 ,  50 . The end section  45  may be designed in a thicker fashion as well, such that there is no deformation at end section  45  at any time during the expansion sequence. In an alternate embodiment, struts  48   a - c  may simply be one thickness along curved  47  and middle sections  49 , and only thicker at end section  45  so as to not deform at that section  45 . In any case, struts  48   a - c  may allow controlled expansion of plates  20 ,  50  of implant  10  via deformation thereof, and in certain embodiments, may limit distraction of plates  20 ,  50 . While only six (6) struts  48   a - c  are shown, it is contemplated that more or less than six (6) struts  48   a - c  may be used. 
         [0020]    As shown in  FIGS. 1-2 , a set of tethers  32 ,  62  may also extend from top and bottom plates  20 ,  50 , respectively. Tethers  32 ,  62  may be deformable, in one embodiment, and may be connected at their ends to an expansion member  80 . Like with struts  48   a - c  above, tethers  32 ,  62  may also share the same structure and function as any of the tethers disclosed in the &#39;939 patent. As such, tethers  32 ,  62  may generally be deformable to allow movement of expansion member  80  with respect to plates  20 ,  50 . Indeed, as shown in  FIG. 3 , tethers  32 ,  62  may include a section  33 ,  63  that is thick and connects with plates  20 ,  50 , such that section  33 ,  63  does not deform during expansion of implant  10 . Tethers  32 ,  62  may also include a separate section  31 ,  61  that is thinner than section  33 ,  63  to deform (e.g., curve or bend) upon movement of expansion member  80 . Lastly, a connection point  35 ,  65  connecting tethers  32 ,  62  to expansion member  80  may also be provided, which is thicker than sections  31 ,  61  so as to not allow deformation at those points  35 ,  65 . Thus, upon movement of expansion member  80 , tethers  32 ,  62  may adequately deform to allow plates  20 ,  50  to separate. 
         [0021]    Referring now to  FIGS. 2-4 , expansion member  80  may be in the form of a wedge with top and bottom angled surfaces  86 ,  88 . Top and bottom angled surfaces  86 ,  88  may also include teeth  90  for engaging with corresponding teeth  36 ,  66  formed on ramp surfaces  21 ,  51  of plates  20 ,  50 . Thus, a ratchet mechanism may be formed in which teeth  90  on angled surfaces  86 ,  88  of expansion member  80  engage successive teeth  36 ,  66  on ramp surfaces  21 ,  51  during movement of expansion member  80  and expansion of implant  10 . In one embodiment, teeth  90  of expansion member  80  and teeth  36 ,  66  on ramp surfaces  21 ,  51  may be configured so that movement of expansion member  80  can proceed in only one direction (e.g., toward the inner cavity of implant so as to expand the same). Thus, once expansion member  80  moves a particular amount towards the inner cavity of implant  10  to expand implant  10 , expansion member  80  (and thus implant  10 ) may be fixed via teeth  36 ,  66 ,  90 . 
         [0022]    Expansion member  80  may further include an inner bore  82  having, in one embodiment, a threaded section  84  ( FIG. 4 ). While threaded section  84  is shown at a distal end of inner bore  82  in the figures, it is contemplated that such threading  84  may be positioned at any point within bore  82 . Expansion member  80  may also have a bulleted or blunt end  92  that is configured to facilitate insertion of implant  10  within intervertebral space. In other words, bulleted or blunt end  92  of expansion member  80  may be designed to wedge itself into the intervertebral space so that implant  10  may be easily implanted therein. 
         [0023]    Referring again to  FIG. 1 , top and bottom plates  20 , of implant  10  may also each include a flange  40 ,  70  that extends beyond plates  20 ,  50  to prevent over insertion of implant and allow for fixation thereof to vertebral bodies  12 ,  14 . Indeed, a surface of flanges  40 ,  70  may be designed to contact portions of adjacent vertebra  12 ,  14 , as shown in  FIGS. 2-4 , to prevent insertion of implant  10  beyond a desired point and allow fixation of implant to vertebrae  12 ,  14 . In one embodiment, flanges  40 ,  70  may also be concavely curved so as to match the convexity of vertebrae  12 ,  14  adjacent flanges  40 ,  70 ; and such flanges  40 ,  70  may include respective apertures  42 ,  72  for receipt of a fixation member  110  therein ( FIG. 4 ). Referring to  FIG. 3 , apertures  42 ,  72  through flanges  40 ,  70  may also be angled to direct fixation members  110  into bone at an angle, the apertures  42 ,  72  including a first section  41 ,  71  for accommodating a shaft  114  of fixation members  110  and a relatively wider second section  43 ,  73  for accommodating a head  112  of fixation members  110 . A step  46 ,  76  may also be formed between sections  41 ,  71  and  43 ,  73  of apertures  42 ,  72 . Thus, fixation members  110  may be countersunk within apertures  42 ,  72  so that head  112  rests on step  46 ,  76  and does not protrude outward from flanges  40 ,  70 . In other embodiments, differently-configured fixation members  110  (e.g., with flat or rounded heads, different sizes, etc.) may be used, and apertures  42 ,  72  may be designed to accommodate such fixation members  110 . Put simply, any fixation member  110  and aperture  42 ,  72  combination may be utilized, so long as implant  10  may be securely fixed to vertebrae  12 ,  14  via insertion of such fixation members  110  into apertures  42 ,  72 . 
         [0024]      FIGS. 1-3  also depict a relief space  30 ,  60  formed in each of top and bottom plates  20 ,  50  adjacent flanges  40 ,  70 , the relief spaces  30 ,  60  facilitating flexion of plates  20 ,  50  during expansion of implant  10 . Relief spaces  30 ,  60  may be formed adjacent flanges  40 ,  70  on either side of implant, although one set of relief spaces  30 ,  60  is not shown in the figures (e.g., those on the far side of implant  10  in  FIG. 1 ). In one embodiment, relief spaces  30 ,  60  are in the form of a cutout or recess in plates  20 ,  50  that, as plates  20 ,  50  are separated, deforms and reduces in size to accommodate expansion of implant  10 . A bore  98  may also be formed through a posterior face of implant  10 , as shown in dashed lines in  FIGS. 2-4  and from a posterior view in  FIG. 5 , such that bone-graft material  120  and/or a portion of a tool  100  (e.g., shaft  102 ) could be placed therethrough. 
         [0025]    A portion of the aforementioned tool  100  is shown in  FIGS. 2-3  as having a shaft  102  with a threaded end  104 . Tool  100  may be inserted through bore  98  of implant  10  to connect with threaded portion  84  of expansion member  80 , and is used in the expansion of implant  10 , as described in more detail below. 
         [0026]      FIGS. 2-4  reflect the various method steps involved in implanting implant  10  and expanding the same. Referring to  FIG. 5 , a surgeon may initially resect a portion or all of an intervertebral disc  18  situated between adjacent vertebral bodies  12 ,  14  so as to create a space between the vertebrae  12 ,  14 . The surgeon should be careful in this instance to not damage the spinal cord  15  (shown with disc  18  in  FIG. 5 ). Tool  100 , and in particular threaded end  104  of shaft  102  ( FIG. 2 ), may then be connected to implant  10  at threaded portion  84  of expansion member  80 , specifically via insertion of shaft  102  through bore  98  in implant  10 , into and through the implant&#39;s  10  inner cavity, and into threaded portion  84  of inner bore  82  of expansion member  80 . Indeed, a handle of tool  100  may simply be rotated so that threaded end  104  of shaft  102  is engaged with threaded portion  84  of expansion member  80 . In this manner, tool  100  may be securely engaged with implant  10  so that implant  10  may be manipulated by the surgeon and implanted into the intervertebral disc space. Tool  100  is also removable from connection with implant  10 , of course, by simply reversing the insertion steps detailed above (e.g., rotating shaft  102  in an opposite direction to disengage threaded end  104  from threaded section  84 ). 
         [0027]    With tool  100  engaged to implant  10 , the surgeon may then insert top and bottom plates  20 ,  50  within the intervertebral disc space, such that teeth  26 ,  56  on bone-contacting surfaces  22 ,  52  of plates  20 ,  50  engage adjacent vertebra  12 ,  14 , as shown in  FIG. 2 . Due to the convexity of bone-contacting surfaces  22 ,  52 , plates  20 ,  50  may also generally conform to the concave shape of the endplates of vertebrae  12 ,  14 . Then, to expand implant  10  within the intervertebral space and maintain adequate separation between vertebrae  12 ,  14 , the surgeon may exert a pulling force on shaft  102  of tool  100 , as indicated by the arrow(s) in  FIG. 3 , to cause expansion member  80  to move towards the inner cavity of implant  10 . At this stage, angled surfaces  86 ,  88  of expansion member  80  may securely engage ramp surfaces  21 ,  51  of plates  20 ,  50  to cause plates  20 ,  50  to distract. In a particular embodiment, since only one (1) expansion member  80  may be utilized, plates  20 ,  50  may predominantly distract at the open end  23  of implant  10  to create an angle  96  ( FIG. 3 ) between plates  20 ,  50 , which, in some cases, may be lordotic to accommodate the natural angle between vertebral bodies  12 ,  14 . To secure implant  10  in its lordotic/expanded state, teeth  90  on expansion member  80  may engage successive teeth  36 ,  66  on ramp surfaces  21 ,  51  during movement of expansion member  80  towards the inner cavity of implant  10 , and expansion member  80  may be precluded from movement in an opposite direction via the engagement between teeth  36 ,  66 ,  90 . 
         [0028]    Simultaneously, during movement of expansion member  80  and expansion of implant  10 , as discussed above, tethers  32 , connected to expansion member  80  may deform or bend at sections  31 ,  61  to accommodate sliding of expansion member  80  along ramp surfaces  21 ,  51 . Tethers  32 ,  62  may also serve to ensure that teeth  90  of expansion member  80  do not disengage from teeth  36 ,  66  on ramp surfaces  21 ,  51 . Indeed, after deformation of tethers  32 ,  62 , such may exert tension on expansion member  80  towards the inner cavity of implant  10  to retain expansion member  80  in place. Also, deformable struts  48   a - c  may serve a similar purpose in that, during expansion of implant  10 , such struts  48   a - c  may deform at curved  47  and/or middle  49  sections to allow distraction of plates  20 ,  50 . And, after and/or during deformation of struts  48   a - c , such may exert tension on plates  20 ,  50  to ensure that expansion progresses uniformly and that plates  20 ,  50  are compressed towards one another to retain expansion member  80  in place. Struts  48   a - c  may also limit distraction of plates  20 ,  50  in some instances. In other words, once implant  10  is expanded, struts  48   a - c  may be placed in tension, such that a force acts on plates  20 ,  50  towards the inner cavity of implant  10 , thereby compressing plates  20 ,  50  against expansion member  80  to secure the same in place. 
         [0029]    It should be noted, additionally, that in some embodiments there is not a need to counteract the pulling force exerted on implant  10  via tool  100  with another opposing force (e.g., by placing another portion of tool  100  or a separate tool against a surface of implant  10  adjacent flanges  40 ,  70 ). In other words, in the figures there is no portion of tool  100  (or a separate tool) that contacts implant  10  adjacent flanges  40 ,  70  to counteract the pulling forces exerted on implant  10  via tool  100  during expansion, although alternate embodiments of the present invention contemplate such a step. As an example, in the &#39;939 patent it is necessary for a portion of deployment tool  350  to contact the implant  10  disclosed therein for expansion of the implant  10  to occur (e.g., second portion  354  of tool  350  contacts an exterior portion of second wedge  18  during expansion of implant  10 ). This is not the case with the present method or tool  100 , although such a step could be performed, if desired. Indeed, in a preferred embodiment, as shown in the figures, implant  10  may sufficiently resist back-out or migration from or within the intervertebral space via the pressure exerted on plates  20 ,  50  by vertebrae  12 ,  14 , and through the friction caused by teeth  26 ,  56  on bone-contacting surfaces  22 ,  52 . If fixation members  110  are inserted into flanges  40 ,  70  prior to expansion, such fixation members  110  may help to prevent back-out and/or migration of implant  10  as well. Thus, the step of contacting implant  10  to resist back-out thereof (i.e., during pulling of tool  100 ) is not necessarily needed. Nonetheless, as noted above, this step is contemplated in alternate embodiments since a tool, such as deployment tool  350  of the &#39;939 patent, is usable with implant  10  of the present invention. Indeed, with minor modifications, the tool  350  of the &#39;939 patent would have applicability in conjunction with implant  10 . 
         [0030]    With implant  10  expanded via tool  100  and secured in its lordotic state, tool  100  may be unscrewed from engagement with expansion member  80  and withdrawn through bore  98  of implant  10 , as reflected by the progression between  FIGS. 3-4 . After removal of tool  100 , the surgeon, at his/her election, may then place bone-graft or other such material  120  through bore  98  of implant  10  and into the inner cavity of implant  10 . Such bone-graft material  120  may be any material, provided the material is adapted to induce bone in-growth into implant  10  (e.g., through vertical aperture(s)  25  in plates  20 ,  50 ). Examples of such materials  120  include natural bone chips, autologous or allograft bone, or synthetic materials such as a bone-graft substitute. Bone morphogenic proteins or other osteoinductive materials may also be used in combination with or apart from material  120 ; and, in some embodiments, certain surfaces of implant  10  may be coated with bone-growth material to facilitate attachment to bone. 
         [0031]    Fixation members  110 , such as bone screws, pins, or other such devices, may then be driven through apertures  42 ,  72  in flanges  40 ,  70  and secured to adjacent vertebra  12 ,  14  to retain implant  10  within the intervertebral space. In particular, shaft  114  of fixation members  110  may be inserted through first section  41 ,  71  of apertures  42 ,  72 , head  112  of fixation members  110  may rest within second section  43 ,  73  of apertures  42 ,  72  on step  46 ,  76 , and step  46 ,  76  may prevent fixation members  110  from being threaded through apertures  42 ,  72 . Alternatively, fixation members  100  may always be inserted within apertures  42 ,  72  in flanges  40 ,  70  prior to expansion of implant  10 , as alluded to above. As shown in  FIG. 4 , fixation members  110  (via the angled nature of apertures  42 ,  72 ) may also be configured to diverge once inserted into vertebrae  12 ,  14  so as to resist back-out. 
         [0032]    It is also worthwhile to note that, due to the nature of expansion member  80  and ramp surfaces  21 ,  51 , implant  10  may be placed in varying lordotic states during expansion. In other words, due to the ratchet structure of implant  10  (i.e., teeth  90  on expansion member  80  and teeth  36 ,  66  on ramp surfaces  21 ,  51 ), implant  10  may be placed at varying lordotic angles, one of which is represented as angle  96  in the figures. This assists with accommodating the differences in lordosis between vertebrae  12 ,  14  of different patients, or at different locations within the spine. Thus, a surgeon may ultimately select the degree of lordosis required by simply moving expansion member  80  less or more along ramp surfaces  21 ,  51  of plates  20 ,  50 . In a particular embodiment, the degree of lordosis that can be achieved with implant  10  is anywhere between about three to about fifteen degrees (≈3-15°). Other degrees of lordosis are also contemplated depending upon the patient being treated, of course. 
         [0033]    In some embodiments of the aforementioned method, multiple implants  10  may be arranged side-by-side within a particular intervertebral space, as shown in  FIG. 5 . Indeed, two (2) implants  10  may be used ( FIG. 5 ) to eliminate the need for posterior screws (e.g., pedicle screws). Such surgeries are sometimes referred to in the industry as a bilateral PLIF (posterior lumbar interbody fusion) stand alone surgery. Multiple levels of the spine may also receive one (1) or more implants  10 , of course. It is also contemplated that, in alternate embodiments, implant  10  may be sized and shaped for implantation within the entire intervertebral space, as opposed to implanting multiple implants  10  side-by-side, as detailed above. 
         [0034]    In still yet other embodiments, a kit of implants  10  may be offered. The kit may include implants  10  of varying sizes to accommodate differently sized patients, and in some embodiments, different implants  10  within the kit may be arrangeable at varying lordotic angles. For example, while a certain amount of implants (e.g., four (4)) within the kit may be offered at one size, and another amount (e.g., four (4)) at another smaller size, it is also contemplated that the differently-sized implants  10  within the kit (i.e., the four (4) large and small implants  10 ) may be expandable via expansion member  80  to or within a different range of lordotic angles. Additional sizes (e.g., large, medium, small, etc.) for implants may also be offered as a kit, and the differently-sized implants  10  within the kit may be arrangeable at or within different ranges of lordotic angles, as discussed above; or in some cases, all implants  10  within the kit may be arrangeable at or within the same range of lordotic angles. Thus, varying combinations of implants  10  of differing sizes and/or that are distractible to different lordotic angles may be offered in kit form. 
         [0035]    In the devices shown in the figures, particular structures are shown as being adapted for use in the implantation, distraction, and/or removal of an expandable implant according to the present invention(s). The invention(s) also contemplates the use of any alternative structures for such purposes, including structures having different lengths, shapes, and/or configurations. For instance, although ramp surfaces  21 , of plates  20 ,  50  and expansion member  80  include ratchet structure for expanding implant  10 , other expansion mechanisms may be utilized to secure expansion member  80  (and thus implant  10 ) in place. As an example, roughened surfaces may be utilized in place of ratchet structure so as to secure expansion member  80  in place and distract plates  20 ,  50 . Other like mechanisms are also contemplated. 
         [0036]    In addition, while a certain number (e.g., six (6)) struts  48   a - c  are shown as extending from plates  20 ,  50 , it is contemplated that any number of struts could be utilized, so long as such struts serve to perform the function(s) recited previously. And, although implant  10  is shown as utilizing only one (1) expansion member  80  to distract plates  20 ,  50  of implant apart, additional expansion members  80  may be used. For instance, plates  20 ,  50  of implant  10  may be provided with multiple ramp surfaces  21 ,  51  and expansion members  80 , each set of ramp surfaces  21 ,  51  and corresponding expansion member  80  being arranged alongside one another within the inner cavity of implant  10 . In other words, as an example, a first set of ramp surfaces  21 ,  51  may be situated at open end  23  of implant  10  to interact with expansion member  80 , as in the figures, while a second set of ramp surfaces (not shown) may be arranged posterior of ramp surfaces  21 ,  51  (e.g., within the inner cavity of implant towards flanges  40 ,  70 ), such second ramp surfaces being configured to interact with a second expansion member. Then, once implant  10  is expanded, each expansion member may interact with its respective ramp surfaces to distract plates  20 ,  50 . In this manner, additional support may be provided to implant  10  once placed in a lordotic state (e.g., plates  20 ,  50  would be supported by two (2) expansion members  80  instead of one (1), as in the figures). What is more, to move multiple expansion members along their corresponding ramp surfaces, it is contemplated that shaft  102  of tool  100  may be provided with multiple threaded sections that engage a threaded bore formed in each respective expansion member. Thus, through a single pulling action, tool  100  may distract plates  20 ,  50  of implant  10  and move the multiple expansion members along their corresponding ramp surfaces. 
         [0037]    As another example, although the connection between tool  100  and expansion member  80  has been discussed as being achieved via threading, it is equally contemplated that other connections are possible, such as compression-fitting, interference-fitting, or the like. For instance, shaft  102  of tool  100  may have a section that is slightly larger than a diameter of bore  98  through expansion member  80  so that, once shaft  102  is inserted into bore  98 , compression results between shaft  102  and bore  98 . Alternatively, shaft  102  may be provided with a set of protrusions extending from opposite sides thereof, and bore  98  may include channels or stops to engage with the protrusions. In this embodiment, shaft  102  may be inserted into bore  98  with protrusions not engaging the aforementioned channels or stops, and then be rotated so that the protrusions on shaft  102  engage the channels and form an interference fit therewith. Put simply, various other connections between shaft  102  and bore  98  are contemplated, so long as the connection allows shaft  102  to securely engage expansion member  80  and implant  10  (e.g., for insertion and expansion of implant  10 ) and be removable therefrom. 
         [0038]    It is also the case that, while only one (1) relief space  30 ,  60  is shown on top and bottom plates  20 ,  50 , multiple relief areas  30 ,  60  may be provided on plates  20 ,  50 . Further, although only one aperture  42 ,  72  is described as being included on flanges  40 ,  70  of each plate  20 ,  50 , multiple apertures for receipt of fixation members therein may be provided on each plate  20 ,  50 . 
         [0039]    As yet another example, while certain steps of the above-described method(s) may have been discussed in a particular order, it is to be understood that the order may be altered in any manner suitable to implant the implant  10  described above. Thus, the order of steps for the method(s) is not essential, and such order may be varied or changed in any manner considered suitable by one of skill in the art. 
         [0040]    Although the invention(s) 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(s). 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(s) as defined by the appended claims. 
         [0041]    It will also be appreciated that the various dependent claims and the features set forth therein can be combined in different ways than presented in the initial claims. It will also be appreciated that the features described in connection with individual embodiments may be shared with others of the described embodiments.