Abstract:
An apparatus for stabilizing and promoting fusion between adjacent vertebrae includes at least a pair of implants to promote bone growth and to fuse with vertebral bone. The implants are joined by a connector. Preferably the implants are inserted into receiving bores in a non-parallel configuration and/or the connector joins the implants so as to bias the implants to a non-parallel configuration. A pair of connecting members also preferably secure the implants to each of the adjacent vertebrae. A method of using the apparatus provides for stabilizing between vertebrae where the original cushioning disc has deteriorated or become damaged. The implants are connected together. Also in the method, the implant receiving bores are non-parallel and/or the implants are biased to non-parallel configurations by joining the implants to the connecting element so as to reduce the inadvertent disturbance of the implants from the receiving bores and to further stabilize the implants overall during the fusion process.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present application is directed to an apparatus and method of stabilizing the spine by placement of implants between effected vertebrae which result in fusion of the vertebrae. In particular, the present application is directed to an apparatus and method of improving the stabilization of the implants during the fusion process by linking the implants that are positioned between the same vertebrae together in pairs and also linking the implants to adjacent vertebrae. Still further the apparatus and method provides some pre-loading or twisting of the implants such that the axes of the implants are not parallel, so that the implants are further stabilized relative to their position between the vertebrae and more difficult to inadvertently dislodge. The linking apparatus provides end caps for helping to support the vertebrae against subsidence onto the cages and to resist rotation of the cages.  
           [0002]    Many millions of people in the United States alone suffer from some type of spinal injury or disease that effects the spine and especially the discs that are located between adjacent vertebrae of the spine. These discs are necessary to properly position and cushion the vertebrae during the movement. Degeneration, injury or other damage to the disc results in improper alignment of and dysfunction of the vertebrae which often also results in severe pain, the inability to move correctly or to perform certain functions, paralysis and other physical problems which may leave the patient totally incapacitated. Approximately ten percent of the persons who have degeneration or herniation of discs are candidates for surgery to correct the problem. Many different systems have been developed to provide relief to persons having defective discs some of which have been effective and some of which have been relatively ineffective. One of the methods of correcting disc defects has been to properly position the adjacent vertebrae relative to each other and then fuse them together in the proper position or alignment.  
           [0003]    Fusing often is best in situations where the discs between the adjacent vertebrae have been either damaged or diseased to such an extent that one or more of the discs no longer functions properly and cannot be preserved by simple procedures such as removal of herniated material and the like.  
           [0004]    One particular type of fusion device which requires insertion of an implant having live bone between the vertebrae has grown in substantial popularity in recent years. In this type of implant, two such devices are often inserted in spaced relationship relative to one another between two adjacent vertebrae in the region normally occupied by the defective disc. In order to accomplish this, at least part of the disc is removed or the entire disc is removed (discectomy) and the intervertebral implant devices, often referred to as cages, are inserted in receiving bores. Such implants have exterior walls which are fenestrated, porous or windowed so as to provide multiple openings therethrough. The interior of each of the implants is filled with live bone harvested from another part of the persons body, such as the hip and after implantation, the bone of the vertebrae grows into and joins with the live bone in the implants such that the two adjacent vertebrae and the implant bone grow into a single mass causing a fusion of the two vertebrae so as to hold them in a desired position. While this procedure reduces flexibility of the vertebrae, it significantly reduces pain and/or nerve damage due to collapse, missing or defective discs and, therefore, the benefits outweigh the lost flexibility. This is especially true where the patient would otherwise be immobile.  
           [0005]    Applicant, as a spinal surgeon, has found that it is desirable to further stabilize the implants, especially during the period between implantation and the time when stabilizing fusion occurs. Consequently, applicant has developed an apparatus and method of joining a pair of implants that are located between two vertebrae in such a manner as to further stabilize the pair such that they are not as likely to become dislodged at some time before the fusion process is complete or afterward. In addition applicant has found it is desirable to secure implants to vertebrae on opposite sides of the implant and to other implants so as to further improve the stability of those implants. Still further, it has been found desirable to form end caps of the linking structure anterior of the cages to provide additional support to the boney endplate of the vertebrae and also to resist rotation of the cages.  
           [0006]    Finally, applicant has found that it is desirable to position the implants such that the central axis of the implants are not parallel to one another prior to joining such that it is more difficult to accidentally remove the implants from bores that receive the implants prior to completion of the fusion process. Yet further applicant has found it desirable to place a slight torque on the implants or preload the implants, such that they are biased against the sides of the bore in opposite directions so as to yet further assist in maintaining the implants between the vertebrae during the fusion process.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is directed to implants utilized to stabilize vertebrae wherein the pad or disc between adjacent vertebrae has deteriorated or been damaged and no longer properly spaces and cushions the vertebrae. Implants of the type of the present invention have been previously used to both separate and support adjacent vertebrae while functioning as a promoter for encouraging bone fusion to occur between the vertebrae. The present invention further stabilizes such implants to allow the implants to form a quicker and stronger fusion platform and, very importantly, reduce the risk that the implants will become unseated, such that either surgery is required to repair them, or that the implants will impinge on a nerve, blood vessel, or other structure and produce serious injury either directly or indirectly due to instability of the vertebrae supported by the implants.  
           [0008]    In particular the apparatus of the invention includes a pair of implants shaped and sized to be received in a bore or alternatively to be driven by tapping between the vertebrae, each having an axis of insertion and each being placed between two adjacent vertebrae. The implants include a central chamber that receives bone for fusion or material to function as a matrix promoting bone growth and has a plurality of radially located apertures between the chamber and the exterior that allow bone from the vertebrae to grow into and fuse with the bone in the chamber. Alternatively, other types of implants may be used including carbon fiber, porous tantalum or any structure compatible with implantation in the human body and adapted to support bone growth so as to join adjacent vertebrae together through promotion of bone growth and fusion. The implants that are secured into bores preferably include an external rough thread that is sized and shaped to be received in a similar thread in the implant receiving bores to assist in securing the implants in the implant receiving bores.  
           [0009]    The implants are joined by a connector. In one embodiment the connector element is an elongate and generally rigid bar of rectangular cross-section that is received in recesses in the front of each implant and secured thereto by fasteners. Preferably, the connector is not aligned to be perpendicular to the central axis is slightly bowed at an angle preferably between about 2° to 10°. This allows the implants to be biased relative to each other such that the implants are non-parallel after completion of the implantation. This urges and preloads the implants into the sidewalls of the implant receiving bores, which may also be non-parallel, and makes it more difficult for the implants to be unintentionally disturbed while in the implant receiving bores or pulled entirely from the bores.  
           [0010]    In a second embodiment the connecting element is a relatively thin plate connecting the implants and also preferably designed to allow the implants to be aligned to be non-parallel. The plate also includes at least one elongate slot so that upon installation, a set screw can slide along the plate during tightening while effectively biasing the implants against the wall of the implant receiving bores.  
           [0011]    In a third embodiment a connecting plate joins two tap-in type intervertebral implants. To gain additional stability a pair of L-shaped connecting plates are secured to the implants near one end thereof and to the adjacent vertebrae. Also the implants between different vertebrae are joinable by a connecting strip.  
           [0012]    In a preferred embodiment the connector is joined to a pair of end caps with one end cap positioned directly anterior of a respective cage. Each end cap has upper and lower surfaces which are elongate and sized and positioned to support the anterior endplate of each vertebrae when the apparatus is fully assembled. The end caps resist subsidence of the vertebrae onto the cages and also resist rotation of the cages. Also, preferably the end caps extend outward sideways relative to the top and bottom of each cage, so as to help support the vertebrae on either side of the cages.  
         OBJECTS AND ADVANTAGES OF THE INVENTION  
         [0013]    Therefore, the objects of the present invention are: to provide a spinal stabilizing system having an apparatus including implants that are positioned in bores between vertebrae having a degenerated or damaged disc wherein the implants include live bone or are constructed of bone growth enhancing material for generating fusion between the vertebrae and wherein the implants are joined for greater stabilization during the fusion process; to provide such an apparatus that provides for proper spacing and alignment between the vertebrae thereby relieving pressure on nerves, restoring strength to the spinal column and correcting other problems associated with vertebrae misaligned due to disc failure or related damage; to provide such an apparatus including structure to further join implants to adjacent vertebrae above and below the implants and other implants so as to additionally improve stabilization of the implant during the fusion process; to provide anterior end caps for each cage that support the anterior endplate of vertebrae spaced by the cages, so as to resist subsidence of the vertebrae onto the cages and to resist rotation of the cages; to provide such an apparatus wherein the implants are joined in such a manner that the axes thereof are nonparallel so as to substantially reduce the likelihood of accidental dislodgement of the implants from the bores in which they are seated or their correct position between the vertebrae; to provide such an apparatus where the implants are biased against the interior walls of the bores so as to further reduce the likelihood of inadvertent removal of the implants from the bores during the fusion process; to provide a method that utilizes the implants in such a manner as to provide an extremely stable implant construction during the fusion process to reduce the likelihood of disturbance of the implants or of accidental removal of the implants from the bores and to speed the fusion process so as to quickly stabilize the patient&#39;s spine; and to provide such an apparatus and method which are relatively simple to use, economical to produce and utilize and that are especially well adapted for the intended usage thereof.  
           [0014]    Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.  
           [0015]    The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a fragmentary perspective view of a patient&#39;s spine showing implants in accordance with the present invention inserted in a region normally occupied by a disc between two vertebrae wherein the implants are joined to each other by a stabilizing structure or apparatus according to the present invention.  
         [0017]    [0017]FIG. 2 is a perspective view of the patients spine prior to insertion of the implants illustrating the insertion of a non-circular spacer between the vertebrae.  
         [0018]    [0018]FIG. 3 is a front view of the vertebrae of the patients spine showing the spacer in phantom lines as the spacer was inserted and showing the vertebrae in phantom lines at the time of first insertion of the spacer and also showing the spacer in solid lines as the spacer is rotated to space the vertebrae that are shown in solid lines, when spaced.  
         [0019]    [0019]FIG. 4 is a perspective view of the patients spine illustrating the pair of vertebrae in spaced relationship to one another and illustrating a bore being produced by use of a drill and drill guide.  
         [0020]    [0020]FIG. 5 is a fragmentary cross-sectional view of the spine illustrating an implant receiving bore being drilled, taken along line  5 - 5  of FIG. 4.  
         [0021]    [0021]FIG. 6 is a fragmentary cross-sectional view of the spine illustrating a top threading the implant receiving bore, taken along line  5 - 5  of FIG. 4.  
         [0022]    [0022]FIG. 7 is a front view of the patient&#39;s spine subsequent to the production of an implant receiving bore by the steps of FIGS. 2 through 6.  
         [0023]    [0023]FIG. 8 is a front view of the patient&#39;s spine showing an implant positioned in the bore formed in steps of FIGS.  2  through  7 .  
         [0024]    [0024]FIG. 9 is a schematic top plan view of a pair of implants prior to joining of the implants.  
         [0025]    [0025]FIG. 10 is a schematic top plan view of the pair of implants subsequent to joining of the implants.  
         [0026]    [0026]FIG. 11 is an exploded and enlarged perspective view of the implants and a connecting element prior to joining of the implants.  
         [0027]    [0027]FIG. 11 a  is a front elevational view of the implants and connecting apparatus, shown in FIG. 11, on a reduced scale and mounted between a pair of spinal vertebrae.  
         [0028]    [0028]FIG. 12 is a perspective view of a portion of a first modified implant system showing an implant, a rod for connecting the implants and a pair of links for connecting the implants to adjacent vertebrae.  
         [0029]    [0029]FIG. 13 is a fragmentary perspective view of the first modified implant system positioned in a patient&#39;s spine between two vertebrae and inter-connecting the vertebrae to the system.  
         [0030]    [0030]FIG. 14 is a front elevational view of a second modified implant system showing two pairs of top-in implants with connectors and a strip joining the connectors.  
         [0031]    [0031]FIG. 15 is a side elevational view of the upper pair of implants of FIG. 14, taken along viewing line  13 - 13 .  
         [0032]    [0032]FIG. 16 is a side elevational view of the lower pair of implants of FIG. 14, taken along viewing line  14 - 14 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.  
         [0034]    The reference numeral  1  generally represents a first embodiment of a spinal stabilization and fusion enhancing apparatus or system  1  in accordance with the present invention shown in FIGS. 1 and 8 through  11   a  and showing installation of the apparatus  1  in FIGS. 1 through 11 a  in the spine  2  of a patient.  
         [0035]    The fusion enhancing apparatus  1  includes a pair of bone receiving cages or implants  10  and  11  that are joined to a connecting plate  12  that joins a pair of end caps  15  and  16  by a pair of set screws  13  and  14  respectively.  
         [0036]    The implants  10  and  11  are designed to be received in a circular bore, but have a somewhat rectangular cross-section with arcing at four opposite corners. Implants of the type illustrated are sold in the marketplace by Spine-Tech Inc. and other manufacturers of spinal fusion type implants. It is foreseen that pairs of implants of a wide range of shapes and constructed of a wide range of materials may be utilized in the invention, provided that the implants are positionable between adjacent vertebrae, that is, intervertebral implants; are compatible with use in the human body; promote, encourage or enhance bone growth into the implant or between the vertebrae and are connectible.  
         [0037]    Each of implants  10  and  11  (best seen in FIG. 11) are elongate and have a central axis A. Each of the implants  10  and  11  also are somewhat annular in shape having a central chamber  20 , surrounded by a wall  21  having an outer surface  22 . The wall  22  is penetrated by a plurality of ports or windows  26  that are radially positioned and open into the central chamber  20 . The outer surface  22  also includes partial threads  27  interspaced at opposite corners with the windows  26 .  
         [0038]    Each implant  10  and  11  has an enclosed rear end  30  and an anterior or front end  31 . The implant front end  31  has a threaded bore  32  that is generally aligned with the axis A and an outer generally planar surface  33 . When installed, bone chips  35 , normally harvested from another part of the body such as the hip, are inserted in the chamber  20  (see FIG. 8).  
         [0039]    The plate  12  is relatively rigid, but has a slight amount of resiliency. The plate  12  joins two spaced end caps  15  and  16  having loops  40  and  41  respectively joined by a connector  42 . The end caps  15  and  16  are sized and shaped to generally sit snugly against the front end surface  33  of each of the implants  10  and  11  so as to be located at least partially directly anterior of a respective implant  10  and  11 . The interior of each illustrated loop  40  and  41  is somewhat oblong. The oblong nature of the loops  40  and  41  is necessary in some cases to allow for various spacing of the implants  10  and  11  and more importantly to allow the second of the set screws  13  or  14  to be started into the associated bore  32 . It is foreseen that in certain embodiments the loops  40  and  41  would not be required to be oblong, but could be circular or the like.  
         [0040]    The end caps  15  and  16  each having a respective generally flat, thick and elongate upper surface  18  and lower surface  19 . The surfaces  18  and  19  being generally parallel and being sized and shaped, such that when the entire apparatus  1  is assembled in a patient between vertebrae  50  and  51 , such as is shown in FIG. 11 a , the surfaces  18  and  19  engage facing interior endplate surfaces  52  and  53  of respective vertebrae  50  and  51 , so as to provide additional support to the vertebrae  50  and  51  and so as to resist subsidence of the vertebrae  50  and  51  with respect to the implants  10  and  11 . The end caps  15  and  16  are sized to be positioned between the implants  10  and  11  and the most forward or anterior part of the vertebrae  50  and  51 . Because the end caps  15  and  16  are secured to a respective implant  10  and  11  so as to resist rotation therebetween and because the surfaces  18  and  19  are elongate and abut the vertebrate surfaces  52  and  53 , the end caps  15  and  16  also help to resist rotation of the generally roundish implants  10  and  11 , so that the implants are less likely to unscrew from between the vertebrae  50  and  51  after assembly, as described below. As is shown in FIG. 11 a , the end caps  15  and  16  extend out sideways to either side of the implants  10  and  11  at the top and bottom of the implants  10  and  11  in the region where the implants  10  and  11  engage the vertebrae  50  and  51 , so as to provide extra support in that region.  
         [0041]    As is seen in FIG. 10, when the apparatus  1  is assembled, the end caps  15  and  16  abut directly against the anterior end of respective implants  10  and  11 . In this manner the end caps  15  and  16  are directly anterior of the implants  10  and  11  and extend outward from the implants  10  and  11  on each side thereof. Each end cap  15  and  16  is preferably also wider from side to side as compared from top to bottom, as seen in FIG. 11 a , so as to resist rotation or instability. That is, the surfaces  18  and  19 , as well as any projections therefrom, extend along and are in touching relationship with the vertebrae on either side of respective implants. While the surfaces  18  and  19  illustrated herein are generally flat, it is foreseen that in some embodiments of the invention the upper and lower surfaces of the end caps may be shaped to closely or almost exactly follow the contour of the base of the vertebrae against which the surfaces rest. In particular, the upper and lower surfaces of the end caps could have a central hump or rise to follow the cage receiving bore and/or may be slopped from anterior to posterior to follow the slight concavity associated with such vertebral surfaces.  
         [0042]    In the present embodiment the end caps  15  and  16  form the plate  12  with the connector  42 . The plate  12  is bowed or bent from top to bottom across the connector  42 . Normally, the angle of the bend will be in the range of 2° to 10° and, in the illustration the angle is about 7° and the bend can be seen in FIGS. 9 and 10. It is foreseen that the end caps  15  and  16  can be non-integral of the connector or may be used independently from the connector, when the connector is not needed or desired.  
         [0043]    The plate  12  is relatively rigid to hold the implants  10  and  11  in a non-parallel relationship to each other as seen in FIG. 10 to make the implants  10  and  11  harder to disturb once implanted and to also provide a slight loading or bias to the implants  10  and  11  in some instances to further stabilize the apparatus  1 .  
         [0044]    The set screws  13  and  14  are sized and shaped to be received through the connector  42  loops  40  and  41  respectively with a head  45 , that is larger in diameter than the loops  40  and  41 , abutting on and snugged against each respective loop  40  and  41 . Each set screw includes a threaded surface  46  below the head  45  that is operably received in a respective implant mainly threaded bore  32 . Each head  45  also includes an opening  47  sized and shaped to receive a driving tool such as an allen wrench, screwdriver or the like (not shown).  
         [0045]    In use, the patient&#39;s spine  2  is exposed and the pair of vertebrae  50  and  51 , having facing surfaces including anterior surfaces  52  and  53  respectively, are surgically exposed, normally by entry from the front of the patient. Although rear entry is possible, front entry is normally considered to be preferred to rear entry.  
         [0046]    The vertebrae  50  and  51  to be stabilized and fused are first separated, since proper spacing has usually been compromised by a defective intervertebral disc or vertebrae damage. To space the vertebrae  50  and  51  a nonsymetrical spacer having a rotating lug  61  is inserted between the vertebrae  50  and  51  on the left or right side (see FIG. 2).  
         [0047]    The spacer  60  is then rotated (as seen in FIG. 3) and the vertebrae  50  and  51  are further spaced as illustrated by the difference between phantom lines (not spaced) and solid lines (spaced) in FIG. 3. Normally the vertebrae  50  and  51  are spaced approximately to the limits of ligaments (not shown) holding the vertebrae  50  and  51  together.  
         [0048]    A guide tool  63  is then positioned opposite the spacer  60 , as seen in FIGS. 4 and 5. The guide tool  63  includes a tube  64  with pins  65  at one end to provide better gripping of the bone. The guide tool  63  aligns the location of a bore  68  to receive one of the implants  10  or  11 . A drill bit  70  is inserted in the guide tool sleeve  64  and the bore  68  is drilled. The drill bit  70  is then removed and a threading tool  71  is inserted to form a coarse thread  72  on the interior of the bore  68  that mates with the thread  27  of implants  10  and  11 .  
         [0049]    The threading tool  71  is removed from the bore  68  and an implant  10  (see FIG. 8) is inserted. The spacer  60  is then removed and the drilling and threading procedure is repeated on the opposite side creating a second bore  74 . The second implant  11  is then inserted in the second bore  74 , as seen in FIG. 1.  
         [0050]    The connecting plate  12  is then attached to the implants  10  and  11  using the set screws  13  and  14 . The implants  10  and  11  may originally be parallel as shown in FIG. 9 or the bores  68  and  74  may be drilled to be non-parallel. In either case, when the plate  12  is secured to the implants  10  and  11  (shown schematically in FIG. 10), the implants  10  and  11  are urged into a non-parallel alignment due to the angle of the bores  68  and  74 , the loading of the plate  12  or both.  
         [0051]    In particular, the set screw  13  is first placed to extend through the loop  40  into the bore  32  of implant  10  and tightened. The second set screw  14  is likewise positioned with respect to implant  11 . As the set screw  14  is tightened the bend in the plate  12  biases the implants  11  and  12  to a non-parallel alignment.  
         [0052]    It is noted that the bores  68  and  74  may also be skewed (not in the same horizontal plane) to give the implants greater gripping and purchase with respect to the vertebrae  50  and  51 , such that the implants  10  and  11  are more likely to resist forces that try to displace the implants  10  and  11  during use.  
         [0053]    The reference numeral  101  generally represents a modified stabilization apparatus or system that is illustrated in FIGS. 12 and 13. The system  101  which is seen installed in a spinal column  103  of a patient in association with and at least partly between a pair of vertebrae  104  and  105 .  
         [0054]    Individual elements of the stabilization system  101  are illustrated in FIG. 102. The system  101  includes a pair of bone receiving and engaging cages or implants  109  and  110 , a connecting element or bar  111  and a pair of connecting members  112  and  113 .  
         [0055]    Each of the implants  109  and  110  is cylindrical in shape having an annular wall  120 . Each wall  120  is porous or heavily fenestrated and includes a plurality of pass through bores or apertures  121  that are generally radially aligned. The exterior of each of the walls  120  also includes a rough helical thread  122  that is aligned with a central axis of each respective implant  109  and  110  and which is designed to help secure each respective implant  109  and  110  in a desired position thereof.  
         [0056]    Each of the implants  109  and  110  includes a rear end  124  for closing the rear end and has a front end  125  that opens into an interior bore  126 . An interior chamber  127  is thus formed between the annular wall  120  and the end cap  125  that is not entirely enclosed as it opens outwardly through the various apertures  121 .  
         [0057]    The chamber  127  receives bone fragments  128  that are harvested from another part of the patient&#39;s body, such as the patient&#39;s hip. The front end  125  of each implant  109  and  110  includes a rectangularly shaped recess sized and shaped to receive the connecting element, plate or bar  111 . The recess  131  has a partial rear wall surface  132 . The bar  111  is not linear but has a bend or curve in the range of 2° to 10°, preferably about 5°. This same feature may be created by a continuous curve or arc located between the implants  10  and  11 . In this manner, when the connecting bar  111  is placed in the recess  131  and abuts against the surface  132 , the two implants  109  and  110  are urged to align in a slightly nonparallel relationship to one another, preferably so as to toe in or converge at the rear ends  124  of the implants  109  and  110  opposite the bar  111 .  
         [0058]    It is foreseen that the axial deviation of the two implants  109  and  110  could also be spread further apart in the rear thereof as opposed to where the implants  109  and  110  join the bar  111 , that is diverge or toeout. On the other hand, the implants  109  and  110  may be aligned to also be skewed relative to one another and/or divergent or convergent.  
         [0059]    The connecting bar  111  is bent on one outer wing  135  thereof to conform to the curvature of the vertebrae  104  and  105 , as shown in FIG. 12. The wing  135  extends outwardly further than the opposite side of the bar  111  and is normally located on the left hand side of the patient. The wing  135  is so located, as surgeons normally enter from the front, but on the left side, so that the patient left hand location allows the surgeon better access.  
         [0060]    Located in the wing  135  is a threaded bore  136  that receives a mating screw  137 . The screw  137  is also received through one of a series of apertures  139  and  140  in each of the connecting members  112  and  113 .  
         [0061]    The connecting member  112  and  113  are L-shaped and each have a second set of threaded apertures  142  and  143  spaced from the wing  135  and positioned opposite the bones  104  and  105  respectfully as shown in FIG. 13. The bone screws  145  and  146  are of the type having a thread  147  on the body for taping into bone and a second thread  148  on the head that is mated with the bores  142  and  143  respectfully.  
         [0062]    The modified apparatus  101  is installed and functions in a similar manner to the apparatus  1  of the previous embodiment with the principal exception that the connecting members  112  and  113  are secured to the adjacent vertebrae  104  and  105  so as to secure the apparatus  101  directly to the vertebrae  104  and  105 .  
         [0063]    Illustrated in FIGS. 14, 15 and  16  is a second modified embodiment of a spinal stabilization apparatus in accordance with the invention, generally identified by the reference numeral  201  and used in conjunction with a spine  202 .  
         [0064]    The apparatus  201  includes a first pair of implants  205  and  206  joined by a first connecting member  207  and a second pair of implants  208  and  209  joined by a second connecting member  210 . The implants  205 ,  206 ,  208  and  209  are similar to the implants of the previous embodiments in that each contains bone and has windows  212  or similar openings extending between an interior chamber holding the bone and an exterior.  
         [0065]    The implants  205 ,  206 ,  208  and  209  are different in comparison to those of the previous embodiment in the shape and method of implantation thereof. The implants  205 ,  206 ,  208  and  209  illustrate implant types that are placed between bones  220 ,  221  and  222  by striking or pushing, sometimes referred to as tap-in type herein, as opposed to being secured by screwing into previously formed bores. Consequently, the implants  205 ,  206 ,  208  and  209  have a rectangular cross section as opposed to circular or near circular cross section.  
         [0066]    The implants  205 ,  206 ,  208  and  209  illustrate several different types. In particular the implants  205  and  206  are each generally rectangular when viewed from the side (see FIG. 15), but have different heights with implant  205  being larger than implant  206 . The implants  205  and  206  are used to support opposite sides of a bone  221  that has deteriorated or been damaged on the side requiring the larger implant  205  to level the opposite sides of the bone  221 .  
         [0067]    The implants  208  and  209  have a trapezoidal configuration when viewed from the side (see FIG. 16) to operably space the front of the bones  222  and  223  more than the rear thereof.  
         [0068]    The connector plates  207  and  210  are similar to the connector plate  12  of the first embodiment and join the implants  205  and  206  as well as the implants  208  and  209  respectively with the one difference being that the plates  207  and  210  each include a centrally located threaded bore  230  that receives a threaded screw  231 . Each of the connector plates  207  and  210  are joined to respective implants  205 ,  206 ,  208  and  209  by set screws  238 .  
         [0069]    An elongate strip  241  operably extends vertically along the front of the spine  202  and joins the connecting plates  207  and  210 . The strip  241  has a series of oval shaped apertures  244  that receive screws  231  so as to secure the strip  241  to each plate  207  and  210  and so as to further stabilize the apparatus  201  and spine  202 .  
         [0070]    The apparatus  201  is installed in a somewhat different manner than that of the previous embodiments. Instead of forming bores to receive the implants, any pad between bones  221 ,  222  and  223  is removed and the implants  205 ,  206 ,  208  and  209  are driven into place by tapping or the like. The connecting plates  207  and  210  are then joined to respective implants  205 ,  206 ,  208  and  209  by set screws  238 , as in the previous embodiments, with the plates  207  and  210  bent to a selected angle. The strip  241  is then joined to each connecting plate  207  and  210  by screws  231 .  
         [0071]    While the implants have mainly been described as cages for receiving bone to enhance bone growth into the cages and to fuse the vertebrae, it is foreseen that other types of implants may be used for this purpose. For example, carbon fiber implants, implants of porous tantalum and other structures of stainless steel, tungsten and other body friendly materials, either coated with bone growth enhancing medium or simply porous so as to support and encourage bone growth into and through the implants, may be utilized in accordance with the invention.  
         [0072]    It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.