Abstract:
Lumbar and cervical interbody or intervertebral devices for implantation between adjacent vertebrae of a spine and/or within intermediary canals of long bones are characterized by a body defining a superior end and an inferior end whose surfaces have serrations or teeth thereon forming anti-backout structures that allow implantation of the body but inhibit removal or backing out therefrom. The one-way structures may extend from the anterior end to the posterior end. The one-way structures may take different shapes but are always configured to allow insertion of the interbody device in an anterior-first manner while preventing and/or inhibiting the interbody device from backing out posteriorly. The various interbody devices may be further characterized by a body defining a cavity that is in communication with the superior and inferior ends of the body and at least one lateral side thereof via openings in the body. Undercuts are formed in the body about the adjacent the openings in order to support bony ingrowth within the void.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is a continuation of U.S. patent application Ser. No. 29/475,313 filed on Dec. 2, 2013, which is a continuation of (and incorporated the disclosure of) U.S. patent application Ser. No. 11/900,944, which was filed on Sep. 14, 2007, which claims the benefit of and/or priority to (and incorporated the disclosure of) U.S. Provisional Patent Application No. 60/844,561 filed Sep. 14, 2006, the complete disclosure of which are hereby incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to interbody and/or cement restrictor devices for implantation between a pair of adjacent vertebrae in order to provide support to the vertebrae and/or promote bone fusion between the vertebrae or for implantation within the intermediary canals of a femur, tibia or humerus. 
         [0004]    2. Background Information 
         [0005]    The disc between vertebrae of a human spine is sometimes damaged due to disease or injury, or may simply deteriorate due to age, disease, injury or congenital defect. With others, the vertebrae may become compressed or otherwise damaged. In these and other cases the vertebrae can become too closely spaced anteriorly which causes an undesired abnormal curvature of the spine with respect to lordosis or kyphosis. 
         [0006]    Because of this, surgery may be utilized to place one or more spacers or interbody devices between adjacent vertebrae to provide proper spacing of the vertebrae and which may also promote fusion between the vertebrae. When a device of this type is utilized for the purpose of promoting fusion, it is often termed a fusion cage or an intervertebral fusion device. When so utilized, bone or bone fusion material is often placed about or in the interbody device(s) in order to promote growth of the bone between the adjacent vertebrae. 
         [0007]    Interbody devices known as cement restrictors may also be used in bones such as the femur, tibia or humerus for the same or similar reasons as vertebral interbody devices. In these cases, the interbody device is implanted within the intermediary canal of the particular bone. 
         [0008]    When interbody devices are used, it is desirable for them to engage as much surface of the bone as possible to provide support to the bone and to thereby reduce the likelihood of subsidence of the device into the bone resulting from contact pressure of the interbody device against bone surfaces. Subsidence can occur since part of the bone is somewhat spongy in nature, especially near the centers of the adjacent vertebrae. 
         [0009]    In summation, the structure of interbody devices mainly functions to support the two adjacent vertebral surfaces, unless the interbody device is also used as a fusion cage within or around which to pack bone fusion material, or to act as a cement restrictor within a long bone. Because it is also desirable in such structures to maintain weight and volume as low as possible in order to make the device more compatible with the body, it is also desirable to make the interbody device as small and lightweight as possible, while still maintaining strength. 
         [0010]    Accordingly, there presently exists a need for improved interbody devices. 
       SUMMARY 
       [0011]    The present invention provides lumbar and cervical interbody or intervertebral devices and/or long bone cement restrictor devices (collectively, interbody devices) for implantation between adjacent vertebrae of a spine and/or within intermediary canals of long bones such as the femur, tibia or humerus. 
         [0012]    In accordance with an aspect of the present invention, the various interbody devices are characterized by a body defining a superior end and an inferior end whose surfaces have serrations or teeth thereon. These serrations or teeth allow easy implantation of the body but inhibit removal or backing out thereof after implantation and thus may be considered one-way structures. In one form, the one-way structures extend from an anterior end to a posterior end (i.e. one side to another of the body). The one-way structures may take different shapes but are always configured to allow insertion of the interbody device in an anterior-first manner while preventing and/or inhibiting the interbody device from backing out posteriorly. 
         [0013]    In accordance with an aspect of the present invention, the various interbody devices are further characterized by a body defining an interior, cavity, void or the like that is in communication with the superior and inferior ends of the body and at least one lateral side thereof via a hole, bore, aperture, fissure, outlet, opening or the like. Undercuts are formed about the cavity adjacent the openings in the body in order to support bony ingrowth within the cavity. The undercuts may be configured in various manners depending on the overall configuration of the interbody device, the various voids formed in the interbody device and/or passages formed in the interbody device that provide communication between one or more interior voids and the exterior of the interbody device. 
         [0014]    Various shapes of interbody devices are disclosed for various applications and/or various positions along the spine or long bone. The interbody devices also may include one or more bores on the posterior end of the body for aiding implantation. Some include markers on the upper and/or lower surfaces thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The above mentioned and other features, advantages and objects of this invention, and the manner of attaining them, will become apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0016]      FIG. 1  is an anterior perspective view of a lumbar interbody device fashioned in accordance with the present principles; 
           [0017]      FIG. 2  is a posterior perspective view of the lumbar interbody device of  FIG. 1 ; 
           [0018]      FIG. 3  is a superior plan view of the lumbar interbody device of  FIG. 1 , the anterior thereof facing to the left; 
           [0019]      FIG. 4  is a side view of the lumbar interbody device of  FIG. 1 , the anterior thereof facing to the left; 
           [0020]      FIG. 5  is an anterior plan view of the lumbar interbody device of  FIG. 1  taken along line  5 - 5  of  FIG. 4 ; 
           [0021]      FIG. 6  is a posterior plan view of the lumbar interbody device of  FIG. 1  taken along line  6 - 6  of  FIG. 4 ; 
           [0022]      FIG. 7  is an anterior perspective view of a lumbar interbody device fashioned in accordance with the present principles; 
           [0023]      FIG. 8  is a superior plan view of the lumbar interbody device of  FIG. 7 , the anterior thereof facing to the right; 
           [0024]      FIG. 9  is an anterior plan view of the lumbar interbody device of  FIG. 7 ; 
           [0025]      FIG. 10  is a sectional view of the lumbar interbody device of  FIG. 7  taken along line  10 - 10  of  FIG. 9 ; 
           [0026]      FIG. 11  is a posterior perspective view of a lumbar interbody device fashioned in accordance with the present principles; 
           [0027]      FIG. 12  is a superior plan view of the lumbar interbody device of  FIG. 11 , the posterior thereof facing to the right; 
           [0028]      FIG. 13  is a posterior plan view of the lumbar interbody device of  FIG. 11 ; 
           [0029]      FIG. 14  is a side view of the lumbar interbody device of  FIG. 11 ; 
           [0030]      FIG. 15  is a sectional view of the lumbar interbody device of  FIG. 11  taken along line  15 - 15  of  FIG. 12 ; 
           [0031]      FIG. 16  is an anterior perspective view of a cervical interbody device fashioned in accordance with the present principles; 
           [0032]      FIG. 17  is a superior plan view of the cervical interbody device of  FIG. 16 ; 
           [0033]      FIG. 18  is a sectional view of the cervical interbody device of  FIG. 16  taken along line  18 - 18  of  FIG. 17 ; 
           [0034]      FIG. 19  is a side view of the cervical interbody device of  FIG. 16 , the anterior thereof facing to the right; 
           [0035]      FIG. 20  is an enlarged fragmentary view of an alternative serration or tooth design applicable to all of the present interbody devices; 
           [0036]      FIG. 21  is a side perspective view of a cement restrictor/interbody device fashioned in accordance with the present principles; 
           [0037]      FIG. 22  is a top plan view of the device of  FIG. 21 ; 
           [0038]      FIG. 23  is a left side view of the device of  FIG. 21  as viewed from the top plan view of  FIG. 22 ; 
           [0039]      FIG. 24  is a bottom view of the device of  FIG. 21  as viewed from the top plan view of  FIG. 22 ; 
           [0040]      FIG. 25  is a sectional view of the device of  FIG. 21  taken along line  25 - 25  of  FIG. 22 ; 
           [0041]      FIG. 26  is an enlarged view of a portion of the sectional view of the device of  FIG. 25  taken along line  26 - 26  thereof; 
           [0042]      FIGS. 27A and 27B  are is a combined top plan view and right side view, respectively, thereof of one size of the device of  FIG. 21 ; and 
           [0043]      FIGS. 28A and 28B  are is a combined top plan view and right side view, respectively, thereof of one size of the device of  FIG. 21 . 
       
    
    
       [0044]    Like reference numerals indicate the same or similar parts throughout the several figures. 
         [0045]    Detail of the features, functions and/or configuration of the components depicted in the various figures will now be presented. It should be appreciated that not all of the features of the components of the figures may necessarily be described. Some of these non-discussed features as well as discussed features are inherent from the figures. Other non-discussed features may be inherent in component geometry and/or configuration. 
       DETAILED DESCRIPTION OF EMBODIMENTS 
       [0046]    Referring to the Figures and in particular to  FIGS. 1-6 , there is depicted an exemplary interbody device, generally designated  10 , fashioned in accordance with the present principles. The interbody device  10  is preferably, but not necessarily, used as a lumbar interbody device and is defined by a generally rectangular body  12 . The body  12  is fabricated from a bio-compatible material such as stainless steel, titanium, a titanium alloy, composite, polymer or the like. The body  12  is sized to be received between adjacent vertebrae but to not extend beyond the periphery of the vertebra. As such, the body  12  may be fabricated in various sizes to accommodate various sizes of lumbar vertebrae. Moreover, the body  12  may be sized such that several interbody devices  10  may be situated as indicated above. 
         [0047]    The body  12  has an anterior end  14  and a posterior end  16  each of which is essentially flat, a superior side  22  having a plurality of serrations or teeth  23 , and an inferior side  24  having a plurality of serrations or teeth  25 . It should be appreciated that since the body  12  is symmetrical, the superior side  22  may be the inferior side while the inferior side  24  may be the superior side, while maintaining the anterior end  14  and the posterior end  16 . Therefore, the terms superior and inferior are arbitrary. The superior side  22  and the inferior side  24  are configured to abut the lower surface of an upper vertebra and the upper surface of a lower vertebra that is adjacent the upper vertebra, respectively. The body  12  also defines a first lateral side  18  and a second lateral side  20 . Again, it should be appreciated that the nomenclature first and second is arbitrary and thus interchangeable. 
         [0048]    The interior of the body  12  is essentially hollow or has a cavity therein that may be used to receive bone growth material and/or for allowing bony ingrowth therein. The interior cavity of the body  12  communicates with the exterior of the body  12  via various openings in the body  12 . Particularly, the superior side  22  has a generally ovoid opening  56  and the inferior side  24  has a generally ovoid opening  58 . The openings  56  and  58  are generally diametrically opposite one another. Moreover, the first lateral side  18  has a generally hourglass depression or concavity  28  having a first essentially pear-shaped bore  30  on one end of the depression  28  that is in communication with the interior of the body  12  and a second essentially pear-shaped bore  32  on the other end of the depression  28  that is in communication with the interior of the body  12 . The second lateral side  20  has a generally hourglass depression or concavity  34  having a first essentially pear-shaped bore  36  on one end of the depression  34  that is in communication with the interior of the body  12  and a second essentially pear-shaped bore  38  on the other end of the depression  34  that is in communication with the interior of the body  12 . 
         [0049]    In accordance with an aspect of the present invention, the body  12  has a first undercut  44  on the interior of the body  12  that extends in an arc from the bore  30  of the first lateral side  18  to the bore  34  of the second lateral side  20  and a second undercut  46  on the interior of the body  12  that extends in an arc from the bore  32  of the first lateral side  18  to the bore  36  of the second lateral side  20 . The arc of the first undercut  44  extends along the inner wall of the posterior end  16 . The arc of the second undercut  46  extends along the inner wall of the anterior end  14 . 
         [0050]    In accordance with another aspect of the present invention, the superior side  22  has a plurality of teeth or serrations  23  that extend from the first lateral side  18  to the second lateral side  20  and define pockets  27  therebetween. As best seen in  FIG. 4 , the teeth  23  project towards the posterior end  16  of the body  12 . This allows the insertion of the interbody device  10  into a disc space (i.e. the space between adjacent vertebrae) in an anterior-first manner while preventing and/or inhibiting the interbody device  10  from backing out posteriorly. Likewise, the inferior side  24  has a plurality of teeth or serrations  25  that extend from the first lateral side  18  to the second lateral side  20  and define pockets  26  therebetween. As best seen in  FIG. 4 , the teeth  25  project towards the posterior end  16  of the body  12 . This allows the insertion of the interbody device  10  into a disc space (i.e. the space between adjacent vertebrae) in an anterior-first manner while preventing and/or inhibiting the interbody device  10  from backing out posteriorly. 
         [0051]    The posterior end  16  also includes a center or main bore  50  that provides communication between the exterior of the body  12  and the interior thereof. First and second side bores  52 ,  54  are also provided in the posterior end  16 . These bores allow the use of a tool to insert the interbody device  10  into the disc space and/or the packing of bone growth material into the interior of the body  12 . 
         [0052]    Referring now to  FIGS. 7-10 , there is depicted another exemplary interbody device, generally designated  100 , fashioned in accordance with the present principles. The interbody device  100  is preferably, but not necessarily, used as a lumbar interbody device and is defined by a generally rectangular body  112 . The body  112  is fabricated from a bio-compatible material such as stainless steel, titanium, a titanium alloy, composite, polymer or the like. The body  112  is sized to be received between adjacent vertebrae but to not extend beyond the periphery of the vertebra. As such, the body  112  may be fabricated in various sizes to accommodate various sizes of lumbar vertebrae. Moreover, the body  112  may be sized such that several interbody devices  100  may be situated as indicated above. 
         [0053]    The body  112  has an anterior end  114  and a posterior end  116  each of which is shown as being flat. These ends, however, may be other than flat. For instance, the ends may be formed as an aggressive bullet shape. The body  112  also has a superior side  122  having a plurality of serrations or teeth  123  and an inferior side  124  having a plurality of serrations or teeth  125 . It should be appreciated that since the body  112  is symmetrical about a longitudinal axis thereof, the superior side  122  may be the inferior side while the inferior side  124  may be the superior side, while maintaining the anterior end  114  and the posterior end  116 . Therefore, the terms superior and inferior are arbitrary. The superior side  122  and the inferior side  124  are configured to abut the lower surface of an upper vertebra and the upper surface of a lower vertebra that is adjacent the upper vertebra, respectively. The body  112  also defines a first lateral side  118  and a second lateral side  120 . Again, it should be appreciated that the nomenclature first and second is arbitrary and thus interchangeable. 
         [0054]    The interior of the body  112  is essentially hollow or has a cavity therein that may be used to receive bone growth material and/or for allowing bony ingrowth therein. The interior cavity of the body  112  communicates with the exterior of the body  112  via various openings in the body  112 . Particularly, the superior side  122  has a generally ovoid opening  156  and the inferior side  124  has a generally ovoid opening  158 . The openings  156  and  158  are generally diametrically opposite one another. Moreover, the first lateral side  118  has a first essentially pear-shaped bore  130  that is in communication with the interior of the body  112  and a second essentially pear-shaped bore  132  that is in communication with the interior of the body  112 . While not discernable in the figures, the second lateral side  120  has a first essentially pear-shaped bore that is in communication with the interior of the body  112  and a second essentially pear-shaped bore that is in communication with the interior of the body  112 . 
         [0055]    In accordance with an aspect of the present invention, the body  112  has ingrowth undercuts in the interior of the body  112 . These undercuts aid in retaining the interbody device in its positioned placement once bony ingrowth occurs. Particularly, the body  112  has a first undercut  159  on the interior of the body  112  that extends in an arc from the bore  130  of the first lateral side  118  to the bore (not shown) of the second lateral side  120  and a second undercut  161  on the interior of the body  112  that extends in an arc from the bore  132  of the first lateral side  118  to the bore (not shown) of the second lateral side  120 . The arc of the first undercut  156  extends along the inner wall of the posterior end  116 . The arc of the second undercut  161  extends along the inner wall of the anterior end  114 . 
         [0056]    In accordance with another aspect of the present invention, the superior side  122  has a plurality of teeth or serrations  123  that extend from the first lateral side  118  to the second lateral side  120  and define pockets  126  therebetween. As best seen in  FIG. 10 , the teeth  126  project towards the posterior end  116  of the body  112 . This allows the insertion of the interbody device  100  into a disc space (i.e. the space between adjacent vertebrae) in an anterior-first manner while preventing and/or inhibiting the interbody device  100  from backing out posteriorly. Likewise, the inferior side  124  has a plurality of teeth or serrations  125  that extend from the first lateral side  118  to the second lateral side  120  and define pockets  127  therebetween. As best seen in  FIG. 10 , the teeth  125  project towards the posterior end  116  of the body  112 . This allows the insertion of the interbody device  100  into a disc space (i.e. the space between adjacent vertebrae) in an anterior-first manner while preventing and/or inhibiting the interbody device  100  from backing out posteriorly. 
         [0057]    Moreover, as best seen in  FIG. 10 , the superior side  122  and the inferior side  124  are not parallel or essentially parallel as are the superior and inferior sides of the interbody device  10 . Rather, the superior and inferior sides  122 ,  124  are tapered inwardly towards each other from the posterior end  116  to the anterior end  114 . This structure provides a significant increase in strength to the loading of the interbody device. 
         [0058]    The posterior end  116  also includes a center or main bore  117  that provides communication between the exterior of the body  112  and the interior thereof. This bore allows the use of a tool to insert the interbody device  100  into the disc space and/or the packing of bone growth material into the interior of the body  112 . 
         [0059]    Referring now to  FIGS. 11-15 , there is depicted another exemplary interbody device, generally designated  200 , fashioned in accordance with the present principles. The interbody device  200  is preferably, but not necessarily, used as a lumbar interbody device and is defined by a generally arc-shaped body  202 . The body  202  is fabricated from a bio-compatible material such as stainless steel, titanium, a titanium alloy, composite, polymer or the like. The body  202  is sized to be received between adjacent vertebrae but to not extend beyond the periphery of the vertebra. As such, the body  202  may be fabricated in various sizes to accommodate various sizes of lumbar vertebrae. Moreover, the body  202  may be sized such that several interbody devices  200  may be situated as indicated above. The body  202  is sized to be received between adjacent vertebrae but to not extend beyond the periphery of the vertebra. As such, the body  202  may be fabricated in various sizes to accommodate various sizes of lumbar vertebrae. Moreover, the body  202  may be sized such that several interbody devices  200  may be situated as indicated above. 
         [0060]    The body  202  has an anterior end  214  and a posterior end  216 , the anterior end of which is arced and the posterior end  216  of which is rounded. The body  202  also has a superior side  222  having a plurality of serrations or teeth  223  and an inferior side  224  having a plurality of serrations or teeth  225 . The superior side  222  and the inferior side  224  are configured to abut the lower surface of an upper vertebra and the upper surface of a lower vertebra that is adjacent the upper vertebra, respectively. The body  202  also defines a first lateral side  216  and a second lateral side  218 . Again, it should be appreciated that the nomenclature first and second is arbitrary and thus interchangeable. 
         [0061]    The body  202  has a first and second hollow or cavity therein that may be used to receive bone growth material and/or for allowing bony ingrowth therein. The first and second cavities communicate with the exterior of the body  202  via various openings in the body  202 . Particularly, the superior side  222  has a first generally oval opening  226  and a second general oval opening  228 . The inferior side  224  has a first generally oval opening (not seen) and a second generally oval opening (not seen). The oval openings are generally diametrically opposite one another. Moreover, the first lateral side  216  has a first essentially pear-shaped bore  230  that is in communication with the first cavity of the body  202  and a second essentially pear-shaped bore  232  that is in communication with the second cavity of the body  202 . While not discernable in the figures, the second lateral side  218  has a first essentially pear-shaped bore (not seen) that is in communication with the second cavity of the body  202  and a second essentially pear-shaped bore (not seen) that is in communication with the second cavity of the body  202 . 
         [0062]    In accordance with an aspect of the present invention, the body  202  has ingrowth undercuts in the interior of the body  202 . These undercuts aid in retaining the interbody device in its positioned placement once bony ingrowth occurs. Particularly, the body  202  has a first undercut  226  in the first cavity of the body  202  that extends in an arc and a second undercut  228  in the second cavity of the body  202  that extends in an arc. The arc of the first undercut  226  extends along the inner wall of the anterior end  214 , while the arc of the second undercut  228  extends along the inner wall of the posterior end  216 . 
         [0063]    In accordance with another aspect of the present invention, the superior side  222  has a plurality of teeth or serrations  223  that extend from the first lateral side  216  to the second lateral side  218 , while the inferior side  224  has a plurality of teeth or serrations  225  that extend from the first lateral side  216  to the second lateral side  218 . As best seen in  FIG. 15 , the teeth  223  and  225  project upwards from the body  202  and are generally evenly spaced. 
         [0064]    Moreover, as best seen in  FIG. 12 , first and second lateral sides  216 ,  218  are curved. This bowing provides a significant increase in strength to the loading of the part. 
         [0065]    The posterior end  214  also includes a center or main bore  234  and first and second side bores  236  and  238  are also provided in the posterior end  16 . These bores allow the use of a tool to insert the interbody device  200  into the disc space. 
         [0066]    Referring now to  FIGS. 16-19 , there is depicted another exemplary interbody device, generally designated  300 , fashioned in accordance with the present principles. The interbody device  300  is preferably, but not necessarily, used as a cervical interbody device and is defined by a generally trapezoidal body  302 . The body  302  is fabricated from a bio-compatible material such as stainless steel, titanium, a titanium alloy, composite, polymer or the like. The body  302  is sized to be received between adjacent vertebrae but to not extend beyond the periphery of the vertebra. As such, the body  302  may be fabricated in various sizes to accommodate various sizes of cervical vertebrae. 
         [0067]    The body  302  has an anterior end  312  and a posterior end  314 , the anterior end  312  being essentially flat while the posterior end  314  is slightly curved. The body  302  also has a superior side  320  and an inferior side  322 . It should be appreciated that since the body  302  is symmetrical about a longitudinal axis, the superior side may be the inferior side while the inferior side may be the superior side, while maintaining the anterior end  312  and the posterior end  314 . Therefore, the terms superior and inferior are arbitrary. The superior side  320  and the inferior side  322  are configured to abut the lower surface of an upper vertebra and the upper surface of a lower vertebra that is adjacent the upper vertebra, respectively. The body  302  also defines a first lateral side  316  and a second lateral side  308 . Again, it should be appreciated that the nomenclature first and second is arbitrary and thus interchangeable. 
         [0068]    The interior of the body  302  is essentially hollow or has a cavity therein that may be used to receive bone growth material and/or for allowing bony ingrowth therein. The interior cavity of the body  302  communicates with the exterior of the body  302  via various openings in the body  302 . Particularly, the superior side  320  has a generally ovoid opening  326  and the inferior side  322  has a generally ovoid opening (not seen) in like manner to the ovoid opening  326 . The openings are generally diametrically opposite one another. 
         [0069]    In accordance with an aspect of the present invention, the body  302  has ingrowth undercuts in the interior of the body  302 . These undercuts aid in retaining the interbody device in its positioned placement once bony ingrowth occurs. Particularly, the body  302  has an undercut  330  in the interior of the body  302  that extends in an arc. In accordance with another aspect of the present invention, the superior side  320  has a plurality of teeth or serrations  321  that extend from the first lateral side  318  to the second lateral side  320  and define pockets therebetween. As best seen in  FIG. 19 , the teeth  321  project towards the posterior end  314  of the body  302 . This allows the insertion of the interbody device  300  into a disc space (i.e. the space between adjacent vertebrae) in an anterior-first manner while preventing and/or inhibiting the interbody device  300  from backing out posteriorly. Likewise, the inferior side  322  has a plurality of teeth or serrations  323  that extend from the first lateral side  318  to the second lateral side  320  and define pockets therebetween. As best seen in  FIG. 19 , the teeth  323  project towards the posterior end  314  of the body  302 . This allows the insertion of the interbody device  300  into a disc space (i.e. the space between adjacent vertebrae) in an anterior-first manner while preventing and/or inhibiting the interbody device  300  from backing out posteriorly. 
         [0070]    The posterior end  314  also includes a center or main bore  328  that provides communication between the exterior of the body  302  and the interior thereof. This bore allows the use of a tool to insert the interbody device  302  into the disc space and/or the packing of bone growth material into the interior of the body  302 . 
         [0071]    Also, it should be appreciated that since the anterior end  312  is smaller in length than the posterior end  314 , the first and second lateral sides  316  and  318  are not parallel to one another. This provides a significant increase in strength to the loading of the part. 
         [0072]      FIG. 20  depicts a fragmentary view of an alternative embodiment of serrations or teeth applicable to the various interbody devices described herein. Particularly, an interbody device body  400  includes teeth or serrations  402  on an inferior and superior surface  401  that face toward the posterior of the interbody device. The teeth  402  define rounded undercuts  404  therein. 
         [0073]    Referring now to  FIGS. 21-26 , there is depicted another exemplary interbody device, generally designated  500 , fashioned in accordance with the present principles. The interbody device  500  may be used as a cervical or lumbar interbody device and is defined by a generally ovoid body  502 . The body  502  is fabricated from a bio-compatible material such as stainless steel, titanium, a titanium alloy, composite, polymer or the like. The body  502  is sized to be received between adjacent vertebrae but to not extend beyond the periphery of the vertebra. As such, the body  502  may be fabricated in various sizes to accommodate various sizes of cervical vertebrae. This is represented in  FIGS. 27A, 27B, 28A, and 28B . 
         [0074]    Particularly,  FIGS. 27A and 27B  depict one size of the interbody device  500  designated  500   a  having the same configuration as the interbody device  500  but with the letter designation “a” after corresponding numerical parts thereof.  FIGS. 27A  shows a top plan view of the interbody device  500   a  on the left side of the figure, and a right side view of the interbody device  500   a  relative to the top plan view on the right side of the figure.  FIGS. 28A and 28B  depict another size of the interbody device  500  designated  500   b  having the same configuration as the interbody device  500  but with the letter designation “b” after corresponding numerical parts thereof.  FIG. 28A  shows a top plan view of the interbody device  500   b  on the left side of the figure, and a right side view of the interbody device  500   b  relative to the top plan view on the right side of the figure. 
         [0075]    Referring back to  FIGS. 21-26 , the body  502  has an anterior end  512  and a posterior end  514 , the anterior end  512  being essentially curved but truncated (flat) at the peak thereof, with the posterior end  514  being also curved. The body  502  also has a superior side  520  and an inferior side  522 . It should be appreciated that since the body  502  is symmetrical about a longitudinal axis, the superior side may be the inferior side while the inferior side may be the superior side, while maintaining the anterior end  512  and the posterior end  514 . Therefore, the terms superior and inferior are arbitrary. 
         [0076]    The superior side  520  and the inferior side  522  are configured to abut the lower surface of an upper vertebra and the upper surface of a lower vertebra that is adjacent the upper vertebra, respectively. The body  502  also defines a first lateral side  516  and a second lateral side  518 . Again, it should be appreciated that the nomenclature first and second is arbitrary and thus interchangeable. 
         [0077]    The interior of the body  502  is essentially hollow or has a cavity  526  therein that may be used to receive bone growth material and/or for allowing bony ingrowth therein. The interior cavity  526  of the body  502  communicates with the exterior of the body  502  via other various openings in the body  502 . 
         [0078]    Particularly, the posterior end  514  has a bore  528  that extends from the exterior of the body  502  to the cavity  526 . The first lateral side  516  has a bore  530  that extends from the exterior of the body  502  to the cavity  516 . A bore  532  is situated at the transition between the posterior end  514  and the first lateral side  516  that likewise extends from the exterior of the body  502  to the cavity  516 . 
         [0079]    In accordance with an aspect of the present invention, the superior side  520  has a plurality of teeth or serrations  521  that extend from the first lateral side  516  to the second lateral side  518 , but between a flat  540  on the superior side  520  proximate the posterior end  514  to a taper  536  on the superior side  520  proximate the anterior end  512 . The teeth  521  project towards the posterior end  514  of the body  502 . This allows the insertion of the interbody device  500  into a disc space (i.e. the space between adjacent vertebrae) in an anterior-first manner while preventing and/or inhibiting the interbody device  500  from backing out posteriorly. Likewise, the inferior side  522  has a plurality of teeth or serrations  523  that extend from the first lateral side  516  to the second lateral side  518 , but between a flat  542  on the inferior side  522  proximate the posterior end  514  to a taper  538  on the inferior side  522  proximate the anterior end  512 . The teeth  523  project towards the posterior end  514  of the body  502 . This allows the insertion of the interbody device  500  into a disc space (i.e. the space between adjacent vertebrae) in an anterior-first manner while preventing and/or inhibiting the interbody device  500  from backing out posteriorly. 
         [0080]      FIG. 26  depicts a fragmentary view of the serrations or teeth  523  of the interbody device  500 . The teeth or serrations  523  define rounded troughs  554  between flats  550  and tapers  552 . The teeth or serrations  523  face toward the posterior of the interbody device. 
         [0081]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.