Abstract:
A spine stabilizing system for retaining a spinal column in a desired spatial relationship during diskectomy and fusion procedures has a plate configured to be positively centered along the midline of the spinal column to maintain the adjacent vertebrae of the spinal column in the desired spatial relationship until the fusion is completed.

Description:
PRIORITY  
       [0001]    This application claims priority to provisional application entitled “CERVICAL SPINE STABILIZING SYSTEM AND METHOD” filed in the United States Patent and Trademark Office on Jun. 7, 2002 and assigned Serial No. 60/387,141, the contents are hereby incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a stabilizing apparatus and method for retaining vertebrae of a spinal column in a desired spatial relationship, and in particular, to a plate and instrumentation for stabilizing the cervical spine during a diskectomy and fusion procedure.  
           [0004]    2. Discussion of the Related Art  
           [0005]    There are many known devices and procedures for retaining vertebrae of the spine in a desired spatial relationship during diskectomies and fusion procedures. These devices maintain the vertebrae in fixed relation with respect to each other by securing the device into the bone of the vertebrae, typically by means of screws. Once secured, the device stays in place during the diskectomy and subsequent fusion procedure. During the procedure, after an incision is made, the device is placed on the spine and is secured to the vertebrae above and below the disk, which is to be removed. The surgeon aligns the device, usually by “eyeballing” the device with respect to the midline of the spine, drills holes into the bones of the vertebra, and then places the screws into the bone through holes in the device.  
           [0006]    The devices and methods of the prior art suffer in general the disadvantage in that proper positioning and true alignment can only be achieved to the degree of accuracy with which the surgeon places the device on the spine. Once the holes are drilled, the patient may be left with a device that is not in true alignment. In the confined region of the cervical spine, a misaligned device can cause serious injury to the patient, particularly after the fusion procedure since the device is left in the patient to ensure fusion occurs. Furthermore, re-drilling the bones of the vertebra can weaken the strength of the bones, since the bones of the cervical spine are smaller than the rest of the spine and may not accommodate multiple holes being drilled in such a small area.  
           [0007]    The devices of the prior art also tend to be cumbersome and are more suited to the thoracic or lumbar spine. Many include rods that permit adjustment of the spatial relationship between the top portion of the device and the bottom portion, so that it can be used to span different vertebrae in the spine. However, these rods are of limited use in the confined region of the cervical spine.  
           [0008]    Therefore, a need exists for a low profile plate device for stabilizing the vertebrae of the spine, in particular the cervical spine, which is adjustable in length to the permit its use with different body sizes. A need also exists for a method of implanting a spine stabilizing plate which allows for accurate placement of the plate with respect to the midline of the spine and prevents damage to the bone of the vertebrae in the event a misalignment occurs and the procedure must be redone.  
         SUMMARY OF THE INVENTION  
         [0009]    It is an object of the present invention to provide a spine stabilization system and instrumentation that facilitates accurate placement of the respect to the midline of the spine.  
           [0010]    It is also an object of the present invention to provide a spine stabilization system and instrumentation that is particularly suited for use with the cervical spine.  
           [0011]    It is a further object of the present invention to provide a low profile cervical stabilization plate that is adjustable in length.  
           [0012]    It is yet a further object of the present invention to provide a method for accurately placing a cervical stabilization plate with respect to the midline of the spine.  
           [0013]    A still further object of the present invention is to provide a method for facilitating a diskectomy and fusion procedure utilizing a stabilizing plate and associated instrumentation that ensures accurate alignment of the plate with respect to the midline of the spine and which minimizes damage to the bones of the vertebra during the alignment of the plate of the vertebra.  
           [0014]    The above and other objects are achieved by the cervical spine stabilization method and system of the present invention. The system and instrumentation of the invention comprises at least a cervical stabilizing plate, a temporary screw placement guide and a locator screw. The cervical stabilization plate includes a frame having an upper portion, a lower portion and at least one intermediate portion extended between the upper and lower portions. Each upper and lower portion of the frame includes a central screw hole for facilitating positioning of the plate onto the vertebrae of the spinal column, and at least one lateral screw hole for mounting the plate to the vertebrae by a bone screw.  
           [0015]    In a preferred embodiment, the cervical stabilization plate is formed by a one-piece frame. In another embodiment, the plate is comprised of a pair of generally U-shaped frame members that face each other when the frames are assembled. The legs of each of the members are joined to each other through the provision of a ratchet-type mechanism that allows for adjustment of the distance between the upper and lower portions of the frame, so that the device can be utilized on different body sizes. Preferably the width of the upper portion is less than the width of the lower portion, which takes into account the narrowing of the width in the cervical spine as the spine moves toward the base of the skull. In addition, a bridge may be provided between the legs of one or both of the U-shaped members to provide additional support.  
           [0016]    A method for facilitating a diskectomy and fusion procedure is also provided. In the method of the present invention, after an incision is made, the locator screw of the present invention is placed in the disc to be removed and aligned by the surgeon. A temporary-screw placement guide is placed over the locator screw, and the vertebra are marked through the holes of the placement guide. Also, temporary screws may be placed into the vertebrae above and below the disc. After vertebra are marked, and/or the temporary screws are in place, alignment is checked through an imaging technique, such as fluoroscopy. If alignment is not confirmed when the temporary screws are in place, the temporary screws are removed, re-aligned, and the procedure continues. If the alignment is confirmed, the bones are drilled through the bone screw holes in the upper and lower portions of stabilizing plate. Permanent screws are then inserted and screwed into the bones. Alignment is then checked again through fluoroscopy, and if alignment is confirmed, then the disk is removed and the fusion procedure is performed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    The above objects, features and advantages of the present invention will become more readily apparent and understood with references to the following detailed description of preferred embodiments of the invention, taken in conjunction with the following drawings, in which:  
         [0018]    [0018]FIG. 1 is perspective view of the cervical plate of the present invention in place on the vertebrae of the spine;  
         [0019]    [0019]FIG. 2 is a partial cross-sectional view of the plate of FIG. 1, taken along the line  22  of FIG. 1;  
         [0020]    [0020]FIG. 3 is a plan view of a second embodiment of the plate of the present invention;  
         [0021]    [0021]FIG. 4 is a plan view of a third embodiment of the plate of the present invention;  
         [0022]    [0022]FIG. 5 is a plan view of a fourth embodiment of the plate of the present invention;  
         [0023]    [0023]FIG. 6 is an exploded perspective view of the plate of FIG. 5;  
         [0024]    [0024]FIG. 7 is a plan view of a fifth embodiment of the plate of the present invention;  
         [0025]    [0025]FIG. 8 is a partial cross-sectional view illustrating placement of a locator screw into the disc that is to be later removed;  
         [0026]    [0026]FIG. 9 is a perspective view illustrated positioning of a temporary screw placement guide of the present invention onto the locator screw;  
         [0027]    [0027]FIG. 10 a  is a perspective view illustrating a first drill guide; FIG. 10 b  is a perspective view illustrating a second drill guide; and FIG. 10 c  is a top plan view of the drill guide of FIG. 10 b ; and  
         [0028]    [0028]FIG. 11 is a flowchart illustrating the method of facilitating a diskectomy and fusion procedure of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0029]    The present invention relates to an apparatus and method for retaining vertebrae of a spinal column in a desired spatial relationship. The present invention is illustrated in association with cervical vertebrae of a human spinal column. It should be understood that vertebrae other than cervical vertebrae of a human spinal column may be retained with the apparatus and method of the present invention.  
         [0030]    Preferred embodiments of the presently disclosed cervical spine stabilization device and method of using the same will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views.  
         [0031]    Referring to FIGS.  1 - 2 , the cervical stabilization plate of the present invention is shown in place on the cervical vertebrae “V 1 ” and “V 2 ” located above and below the disc to be later treated or removed. Plate  20  includes a substantially square shaped frame  22 . Frame  22  includes upper portion  24 , lower portion  26  and at least one intermediate portion  28  extended between the upper and the lower portions. Upper and lower portions respectively include central screw holes  30 ,  32  at the center positions thereof for receiving temporary positioning screws  34  and  36 , which will be later described in detail. Upper and lower portions preferably include ear portions  38 ,  40  and at least one lateral screw hole  42 ,  44 , preferably four holes at the four corners of the frame. Lateral screw holes  42 ,  44  are provided for mounting the plate  20  to the vertebrae by bone screw  46 ,  48 , which will be described later in detail.  
         [0032]    Referring now to FIGS.  3 - 7 , further embodiments of the cervical stabilization plate of the present invention are shown. Cervical stabilization plate  60  (FIG. 3) is similar to the plate  20  of FIG. 1 except that plate  60  is of square configuration with two parallel intermediate leg portions  28   a . Cervical stabilization plate  70  (FIG. 4) is similar to the plate  60  of FIG. 3 except that plate  70  consists of a pair of generally U-shaped frame members  72 ,  74  that face each other when the frames are assembled as shown in the figure. Frames  72 ,  74  included leg portions  76 ,  78  which are joined to each other by ratchet mechanism  80 . As shown in FIG. 6, ratchet mechanism  80  includes ratchet  82  at one leg portion and connection member  84  at the other leg portion to be joined. Ratchet mechanisms are known in the art and allow for adjustment of the distance between the two joining frames, so that the plate  70  can be utilized on different body sizes or providing fine adjustment at the site. Cervical stabilization plate  90  (FIGS.  5 - 6 ) is similar to the plate  20  of FIG. 1 except that plate  90  is formed by a pair of generally U-shaped frame members  92 ,  94  and joined by ratchet mechanism  80  as described above. Cervical stabilization plate  100  (FIG. 7) is similar to the plate  90  of FIG. 5 except that plate  100  further includes bridge  102  extending between two leg portions for providing additional support to the plate.  
         [0033]    Referring now to FIGS.  8 - 9 , further instrumentation for stabilizing vertebrae in accordance with the present invention is described herein. Locator screw  110  includes screw portion  112  and head portion  114  preferably with a circular configuration. Temporary screw placement guide  120  includes body portion  122 , upper portion  124  and lower portion  126 . Body portion  122  includes locator hole  128  for receiving the head portion  114  of the locator screw  110  in a slidable fit manner. Upper and lower potions  124 ,  126  include temporary screw holes  130 ,  132  for guiding the insertion of temporary positioning screws  34 ,  36  at suitable locations into the vertebrae V 1  and V 2 . Temporary positioning screws  34 ,  36  have a similar configuration to locator screw  110  described above.  
         [0034]    Referring to FIGS.  8 - 11 , a method for stabilizing vertebrae utilizing the system of the present invention is described herein.  
         [0035]    The surgical operations site involving cervical vertebrae to be treated is accessed through incision by a surgical knife and thereby exposing the target spinal area. Locator screw  110  (FIG. 8) is placed by an insertion tool into disc “D” at a midline location. The location of the screw  110  may be accurately checked through an imaging technique, such as fluoroscopy. Temporary screw placement guide  120  (FIG. 9) is then placed over the locator screw  110  with the head of the screw  110  inserted over locator hole  128  of the guide  120 . The location of temporary screw holes is adjusted to coincide the midline of the spine by rotating the guide  120  about the locator screw  110 . Temporary positioning screws  34 ,  36  (FIG. 2) are then placed through the screw holes  130 ,  132  of the guide  120  and into the vertebrae V 1  and V 2 . It is preferable to drill pilot holes into the vertebrae V 1  and V 2  before the insertion of the temporary screws  34 ,  36  as described above, although marking of the vertebra is also contemplated. Alignment of the temporary screws with respect to the spine is checked through an imaging technique such as fluoroscopy. If alignment is confirmed, guide  120  is then removed, and a drill guide  200 ,  210  such as shown in FIGS. 10 a - c  is placed over temporary screws  34 , 36  at post  205  or notch  206 . Holes are drilled through the guide posts  220 . The drill guide is removed after confirming alignment, and the cervical stabilization plate of the present invention, such as plates  20 ,  60 ,  70 ,  90  and  100  in FIGS.  1 - 7 , is placed over the temporary screws  34  and  36  with such screws fit into the screw holes  30 ,  32  as shown in FIG. 2. If alignment is not confirmed, the temporary screws are removed and the aforementioned procedure is repeated. Bone screws  46 ,  48  are inserted through the screw holes  42 ,  44  of the plate, thereby securing the plate firmly to the cervical spine. Alignment of the plate may be again checked using the fluoroscopy procedure. If alignment is confirmed, disc “D” is then removed and the subsequent fusion procedure is performed. FIG. 11 summarizes the process of the present invention.  
         [0036]    It will be understood that various modifications may be made to the embodiments disclosed herein.