Abstract:
An intervertebral implant system for positioning between an upper vertebra and a lower vertebra is provided. The implant system comprises an intervertebral implant and a staple. The implant comprises an inferior plate and a superior plate, while the superior plate has a vertebral surface facing the upper vertebra and the inferior plate has a vertebral surface facing the lower vertebra. There are two grooves on at least one vertebral surface extending at an angle outward from a centerline on the vertebral surface as they extend from the anterior portion of the plate toward the posterior portion of the plate. When in use, the staple is associated with the two grooves for maintaining stability of the intervertebral implant and preventing backing out of the intervertebral implant. The staple also has two arms and has a generally rectangular shape prior to use.

Description:
TECHNICAL FIELD 
     The present invention relates generally to intervertebral implants and more particularly, to providing stability to such spinal implants when they are inserted between vertebrae to replace vertebral discs. 
     BACKGROUND 
     The human spine is a biomechanical structure with thirty-three vertebral members, and is responsible for protecting the spinal cord, nerve roots and internal organs of the thorax and abdomen. The spine also provides structural support for the body while permitting flexibility of motion. A significant portion of the population will experience back pain at some point in their lives resulting from a spinal condition. The pain may range from general discomfort to disabling pain that immobilizes the individual. Back pain may result from a trauma to the spine, be caused by the natural aging process, or may be the result of a degenerative disease or condition. Similarly, neck pain may occur in related ways, i.e., from injury, aging or disease. 
     The intervertebral disc functions to stabilize the spine and to distribute forces between vertebral bodies. A normal disc includes a gelatinous nucleus pulposus, an annulus fibrosis and two vertebral end plates. The nucleus pulposus is surrounded and confined by the annulus fibrosis. 
     It is known that intervertebral discs are prone to injury and degeneration. For example, herniated discs are common, and typically occur when normal wear, or exceptional strain, causes a disc to rupture. Degenerative disc disease typically results from the normal aging process, in which the tissue gradually looses its natural water and elasticity, causing the degenerated disc to shrink and possibly to rupture. These conditions often are treated with the use of intervertebral implants. 
     In particular, areas of the cervical spine and the lumbar spine are particularly prone to the need for intervertebral implants, or artificial disc implants because they are areas where the spine is particularly dynamic. Thus, the implants that are used often are dynamic or motion-preserving implants. There are challenges, however, with dynamic implants and when there are problems, comes poor performance. For example, maintaining the stability of dynamic implants in the disc space, or merely preventing such dynamic implants from backing-out of the disc space after they are surgically inserted are some such challenges. 
     There, therefore, is a need to increase the stability of dynamic implants in the disc space and also a need to prevent backing-out of such devices after they have been implanted. Further, there is a need to do so without the use of anchors or flanges on the disc and the need for extra preparation of the endplates of the vertebrae for such extra features. 
     SUMMARY 
     An intervertebral implant system for positioning between an upper vertebra and a lower vertebra is provided. The implant system comprises an intervertebral implant and a staple. The implant comprises an inferior plate and a superior plate, while the superior plate has a vertebral surface facing the upper vertebra and the inferior plate has a vertebral surface facing the lower vertebra. There are two grooves on at least one vertebral surface extending at an angle outward from a centerline on the vertebral surface as they extend from the anterior portion of the plate toward the posterior portion of the plate. When in use, the staple is associated with the two grooves for maintaining stability of the intervertebral implant and preventing backing out of the intervertebral implant. The staple also has two arms and has a generally rectangular shape prior to use. 
     The end of each arm of the staple is pointed. In some versions, the grooves are wider at the anterior portion of the plate than at the posterior portion of the plate. Also, the implant further comprises a stop situated on the anterior side of at least one of the plates such that the at least one plate does not move too far into the disc space. The implant further comprises a screw for fastening the staple into the at least one plate to which the staple is inserted. In some versions, the intervertebral implant system further comprises a second staple for fastening the staple into the other of the superior or inferior plate such that both the superior and inferior plates each have a single staple helping to maintain stability of the intervertebral implant and to prevent backing out of the intervertebral implant. With the intervertebral implant system of the present invention, it is preferred that the two grooves on the at least one vertebral surface extend at an angle outward from the centerline on the vertebral surface in the range of 10 degrees to 15 degrees from the anterior portion of the plate toward the posterior portion of the plate. 
     A different embodiment of the intervertebral implant system of the present invention comprises an intervertebral implant as described above and a staple, wherein the staple has a left half and a right half. Other than this difference, the characteristics of this embodiment are similar to that of aforementioned embodiments, i.e., for example, the shape of the staple, having stops, pointed ends and angles of the arms of the staple. 
     Additional aspects and features of the present disclosure will be apparent from the detailed description and claims as set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a top isometric view of a spinal implant of the present invention. 
         FIG. 2  shows a front view of the spinal implant of  FIG. 1 . 
         FIG. 3  shows an isometric view of the first or third embodiments of the V-shaped staple of the present invention. 
         FIGS. 4A and 4B  shows isometric views of the procedure for implanting the first embodiment of the V-shaped staple of the present invention. 
         FIG. 5  shows an isometric view of the second embodiment of a spinal implant of the present invention. 
         FIG. 6A  shows the V-shaped staple that cooperates with the second embodiment of the spinal implant. 
         FIG. 6B  shows the second embodiment of the V-shaped staple inserted in a spinal implant. 
         FIGS. 7A ,  7 B and  7 C shows top views of the procedure for implanting the second embodiment of the V-shaped staple into the superior plate of the spinal implant of the present invention. 
         FIG. 8  shows the second embodiment of the V-shaped staple in cooperation with both the superior and inferior plates of an intervertebral disc. 
         FIGS. 9A and 9B  shows top views of the procedure for implanting the third embodiment of the V-shaped staple into the superior plate of the spinal implant of the present invention. 
         FIG. 10  shows the third embodiment of the V-shaped staple of the present invention in cooperation with both superior and inferior plates of an intervertebral disc. 
     
    
    
     DETAILED DESCRIPTION 
     For the purpose of promoting an understanding of the principles of the present disclosure, reference is made to the specific embodiments illustrated in the drawings, and specific language is used to describe the embodiments. It is nevertheless understood that no limitation of the scope of the present disclosure is intended. Any alterations and further modifications of the described embodiments, and any further applications of the principles of the present disclosure as described herein, are fully contemplated, as would occur to one skilled in the art to which the invention relates. 
     As mentioned above, there is a need to increase the stability of dynamic implants in the disc space and also prevent backing-out of such devices after they have been implanted. Moreover, there is a need to do so without the use of anchors or flanges on the disc and the need for extra preparation of the endplates of the vertebrae for such extra features. 
       FIG. 1  shows a top isometric view of an artificial disc or spinal implant  15  of the present invention. In particular,  FIG. 1  shows a superior plate  20  and an inferior plate  10 , which cooperate together with articulating surfaces. Shown on the superior plate  20 , however, are grooves  30  and  32 . At the anterior portion  22  of the plate  20 , the groove  30  is relatively wide and it narrows as it extends toward posterior portion of the disc  15  or plate  20 . Thus, at the posterior portion of the plate  20 , the groove is labeled  32  as it is relatively narrow. Also shown in  FIG. 1  is a stop  23 , which will be discussed below. Located in or around the stop  23  is a hole  21 , which also will be discussed below. 
       FIG. 2  shows a front view of the spinal implant  15  of  FIG. 1 . In particular,  FIG. 2  shows a ball-and-socket or ball-and-trough type mechanism  12  of the spinal implant  15 , which allows the plates or plates  10  and  20  to articulate, which thereby allows the adjacent vertebrae to which they have been affixed to have motion after the artificial disc  15  is implanted. Located in or around stops  23  and  13 , are holes  21  and  13 , respectively, which will be discussed below. 
       FIG. 3  shows a V-shaped staple  40 , which is part of the first embodiment of the present invention. The V-shaped staple  40  comprises two arms  44 , and each arm  44  has an end  48  which is pointed (or sharp) for penetrating the endplate of each vertebrae to which the plates  10  or  20  are being affixed. The overall shape of the staple  44  before use can be described as generally rectangular. V-shaped staples of the present invention may be made from materials including titanium, titanium alloys such as nickel-titanium, stainless steel and cobalt chromium, PEEK, PEEK-carbon composites and/or any combination of the above. 
     In isometric views,  FIGS. 4A and 4B  demonstrate the procedure, and specifically the beginning and end stages, for implanting the V-shaped staple  40  into the superior plate  20  of the spinal implant  15  of the present invention. In  FIG. 4A , the V-shaped staple  40  is introduced to the implant  15  and the vertebra (not shown). The V-shaped staple  40  can simply be hammered or power-driven through the vertebra that lies above the superior plate  20 , while the V-shaped staple  40  moves through the grooves  30  and  32 . That is, because of the material of the V-shaped staple  40  and the shape of the groove  30 , the V-shaped staple  40  will yield to the groove  30  and change shape from a generally rectangular shape of  FIG. 3  to the V-shaped staple of  FIGS. 4B . That is, the angle α of each arm  44  of the V-shaped staple  40  from centerline CL (which also can be described as an angle outward from the centerline it moves from the anterior portion to posterior) is in the range of ½ degree to 15 degrees. Such an angle will both allow for the V-shaped staple  40  to enter the vertebrae and groove  30 , and also allow for the staple  40  to achieve the purpose of the invention, which is to provide stability to the spinal implant, particularly transverse stability, while also preventing backing out of the implant. Further, note that the relatively narrow grooves  32  toward the posterior end of the plate  20  work to fix or lock the staple  40  in the final position. Also note that for the second embodiment of the V-shaped staple of the present invention, a different range of angle α, is preferred. 
       FIG. 4B  also shows the stop  23  on the superior plate  20 . The stop  23  helps prevent the V-shaped staple  40  from causing the plate  20  from moving too far into the disc space. After the V-shaped staple  40  is fully inserted into place, a screw  42  is inserted through hole  41  in staple  40  and into stop  23  and/or partially or directly into plate  20 , i.e., depending on the location of hole  41 . Specifically, screw  42  maintains stability between the V-shaped staple  40  and each respective plate  10  or  20  of the spinal implant  15 . Note that this present procedure and spinal implant  15  is described with reference to the superior plate  20  for illustrative purposes only. That is, it is preferred that a V-shaped staple (in any embodiment described herein) is used on both the superior and inferior plates  20  and  10 , respectively, for maximum stability and results, e.g., to prevent backing out. 
       FIG. 5  shows an isometric view of a second embodiment of a spinal implant  115  of the present invention. In particular,  FIG. 5  shows a superior plate  120  and an inferior plate  110 , which cooperate together with articulating surfaces such as a ball-and-socket mechanism of  FIG. 2 . Shown on the superior plate  20 , and as opposed to the embodiment  15  of  FIG. 1 , the grooves  130  are relatively narrow and of the same width throughout their length. Similar to the embodiment  15 , however, implant  115  also contains a stop  123  on its superior plate  120 . Located in or around the stop  123  is a hole  121  for a screw  142  (shown in  FIG. 6B ) to be inserted. 
       FIG. 6A  shows the V-shaped staple  140  that cooperates with the second embodiment of the spinal implant  115 . The V-shaped staple  140  comprises two halves or parts  144  and  146 , instead of the two arms  44 , and like V-shaped staple  40 , each end  148  is pointed for penetrating the endplate of each vertebrae to which the plates  110  or  120  are being affixed. 
       FIG. 6B  shows V-shaped staple  140  already inserted in spinal implant  115 .  FIG. 6B  also shows both the superior  120  and inferior  110  plates of the spinal implant  115 , as well as the fastening screw  142  of the V-shaped staple  140 . As compared to V-shaped staple  40 , V-shaped staple  140  is shaped more like a “V” prior to use (as well as during use) from the start, and as shown in  FIGS. 6A and 6B , V-shaped staple  140  can be stiffer than V-shaped staple  40  in that it does not need to bend to accommodate insertion in the grooves of the plates. The two parts or halves of V-shaped staple  140  allows one half  144  to be inserted, and then the next half  146  to be inserted thereafter, allowing for each part to be relatively rigid. Thus, the V-shaped staple  140  provides stability to the spinal implant, particularly transverse stability, while also preventing backing out of the implant in a relatively rigid manner. 
     In top views,  FIGS. 7A ,  7 B and  7 C demonstrate the procedure, and specifically the beginning, middle and end stages, for implanting the V-shaped staple  140  into the superior plate  120  of the spinal implant  115  of the present invention. In  FIG. 7A , the left half  144  of the V-shaped staple  140  is introduced to the implant  115  and the vertebra (not shown). The left half  144  of the V-shaped staple  140  can simply be hammered or power-driven through the vertebra that lies above the superior plate  20 , while it moves through groove  130 . In  FIG. 7B , the right half  146  of the V-shaped staple  140  is introduced into the implant  115  and the vertebra, such that the holes  141 A and  141 B in each half (shown in  FIG. 6A ) line up over each other. The left half  146  of the V-shaped staple  140  can similarly be hammered or power-driven through the vertebra that lies above the superior plate  120 , while it moves through groove  130 . Then, as shown in  FIG. 7C , when the halves  144  and  146  are fully in place, the fastening screw  142  can be inserted through holes  141 A and  141 B and into stop  123  to secure the V-shaped staple  140  to the implant  115 . The same angle of the halves (or arms)  144  and  146  from center (or centerline) for the first embodiment of the present invention also is preferred for this second embodiment for achieving maximum stability to the spinal implant, particularly transverse stability, while also preventing backing out of the implant. 
       FIG. 8  shows the second embodiment of the V-shaped staple  140  of the present invention in cooperation with both the superior and inferior plates  120  and  110 , respectively, to achieve maximum stability and results, e.g., to prevent backing out. Specifically, a V-shaped staple  140  is shown in cooperation with a superior plate  120 , and a V-shaped staple  150  is shown in cooperation with an inferior plate  110 , where plates  120  and  110  are part of the same artificial disc  115 . 
     A third embodiment of the present invention is illustrated and described with reference to  FIGS. 3 ,  5 ,  9 A,  9 B, and  10 .  FIG. 3  shows the third embodiment of a V-shaped staple  240 , while  FIG. 5  depicts an artificial disc  115  that also can be used with V-shaped staple  240 . Like the first two embodiments, the V-shaped staple  240  is made of the same materials, but typically is of a smaller thickness. Specifically, for the first and third embodiments of the V-shaped staple, the preferred range of thickness is in the range of 0.3 mm. to 1.0 mm. for metal materials, and 0.5 mm. to 3.0 mm. for non-metal materials. For the second embodiment, although it can be thinner than the other embodiments, the preferred range of thickness is in the range of 0.3 mm. to 3.0 mm. for all materials. Similarly, for the first and third embodiments of the V-shaped staple, the preferred range for angle α from the centerline CL is ½ degree to 15 degrees. For the second embodiment, however, the preferred range for angle α from the centerline CL is ½ degree to 65 degrees, and a more preferred range for α from the centerline CL is 10 degrees to 30 degrees. 
     Accordingly,  FIGS. 9A and 9B  demonstrate the procedure, and specifically the beginning and end stages, for implanting the V-shaped staple  240  into the superior plate  220  of the spinal implant  215  of the present invention. In  FIG. 9A , the V-shaped staple  240  is introduced into the implant  215  and the vertebra (not shown). With the aid of the pointed ends  248 , the V-shaped staple  240  can simply be hammered or power-driven through the vertebra that lies above the superior plate  220 , while it moves through groove  230 . Because the staple  240  is relatively thin, it can yield to the angle of the groove  230  as it enters the implant  215 , as shown in  FIG. 9A . In  FIG. 9B , when the V-shaped staple  240  is fully in place, the fastening screw  242  can be inserted through hole  41  and into stop  223  to secure the V-shaped staple  240  to the implant  215 . The same angle of the halves  144  and  146  (or arms) from center for the first embodiment of the present invention also is preferred for this third embodiment for achieving maximum stability to the spinal implant, particularly transverse stability, while also preventing backing out of the implant. 
       FIG. 10  shows the third embodiment of the present invention V-shaped plate  240  in cooperation with both the superior and inferior plates  220  and  210 , respectively, for maximum stability and results, e.g., to prevent backing out. Specifically, a V-shaped staple  240  is shown in cooperation with a superior plate  220 , and a V-shaped staple  250  is shown in cooperation with an inferior plate  210 , where plates  220  and  210  are part of the same artificial disc  215 . 
     Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this disclosure. Accordingly, all such modifications and alternative are intended to be included within the scope of the invention as defined in the following claims. Those skilled in the art should also realize that such modifications and equivalent constructions or methods do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. It is understood that all spatial references, such as “horizontal,” “vertical,” “top,” “upper,” “lower,” “bottom,” “left,” and “right,” are for illustrative purposes only and can be varied within the scope of the disclosure. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.