CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is a continuation of, and claims a benefit of priority under 35 U.S.C. 120 of the filing date of U.S. patent application Ser. No. 11/085,672, entitled “VARIABLE GEOMETRY OCCIPITAL FIXATION PLATE,” filed Mar. 21, 2005, the entire contents of which are hereby expressly incorporated by reference for all purposes. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to fixation devices used in orthopedic surgery. This invention relates more particularly to devices used for cervical posterior fixation by means of a plate attached to a bone in the occipital region and secured to a rod which attaches to a cable, wire, plate, or screw fastened in the spinal region. 
       BACKGROUND 
       [0003]    Fixation devices are used in orthopedic surgery to stabilize bones such as those in the spinal column. One type of fixation device includes a plate attachable to a portion of a bone. The plate may be connected to another bone or another portion of the same bone, directly or through other connecting devices. For example, posterior fixation devices can include a plate fastened to the skull, or occiput, one or more rods running longitudinally along the spine and connected to the plate, and plates, cables, wires, hooks, screws, or other connectors attached to a vertebra and connected to the rod. 
         [0004]    A number of such mechanisms are known in the act. To accommodate the variation in patient size and anatomy, a plate often needs to be chosen from a set of plates of multiple sizes and/or varying geometry. This results in a higher cost of the device assembly and a need to maintain separate inventory of the various size and geometry devices. It also increases the surgical time because the surgeon must search for the device that best fits the patient. Accordingly, there is a need for an improved fixation plate. 
       SUMMARY 
       [0005]    A fixation device for connecting a stabilization device to a bone comprises a first member comprising a first portion for attachment to a bone; a second member comprising a second portion for attachment to a bone and connected to the first member by a pivotal connection such that the first and second portions are spaced apart by an adjustable distance, at least one of the first and second members further comprising a portion for mounting a connector adapted to secure a stabilization device 
         [0006]    A method of attaching a stabilization device to a bone comprises attaching a first plate to a bone at a first portion on the first plate; attaching a second plate, pivotally attached to the first plate, to a bone at a second portion on the second plate; pivotally adjusting the position of the second plate relative to the first plate to adjust the distance between the first portion and the second portion; and attaching a stabilization device to either the first plate or the second plate. 
         [0007]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a variable geometry occipital device, according to one embodiment of the present invention. 
           [0009]      FIG. 2  shows a perspective view of the variable geometry occipital fixation device of  FIG. 1   
           [0010]      FIG. 3  shows an exploded view of the variable geometry occipital fixation device of  FIG. 1 . 
           [0011]      FIG. 4  shows another exploded view of the variable geometry occipital fixation device of  FIG. 1  after insertion of the attachment bosses. 
           [0012]      FIG. 5A  shows a top plan view of the variable geometry occipital fixation device of  FIG. 1  in its narrowest configuration. 
           [0013]      FIG. 5B  shows a top plan view of the variable geometry occipital fixation device of  FIG. 1  in its widest configuration. 
           [0014]      FIG. 6  shows an exemplary method of using the variable geometry occipital fixation device of  FIG. 1 . 
       
    
    
       [0015]    While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0016]      FIG. 1  shows a variable geometry occipital device  10  in one embodiment of the present invention. The variable geometry occipital device  10  in this case is affixed to the occiput  2  of the patient  4 . One or more rods  6  are attached to the device  10  and run substantially along the spine column  8  and are attached to various segments of the spinal column  8 . 
         [0017]      FIG. 2  shows a perspective view of the variable geometry occipital device  10  of  FIG. 1 . The variable geometry occipital fixation device  10  includes a first lateral member  12 , a second lateral member  14 , and a midline member  16 . The first lateral member includes a proximal end  18 , a distal end  20 , and an attachment bore  22  located at the distal end  20 . 
         [0018]    The second lateral member includes a proximal end  24 , a distal end  26 , and an attachment bore  28  located at the distal end  26 . The midline member includes a proximal end  30  and a distal end  32 . In the embodiment shown in  FIG. 2 , the proximal ends  18 ,  24 , and  30  are stacked on top of each other. Attachment bosses  34  are inserted into the attachment bores  22  and  28 . Each attachment boss  34  has a slot  35  for receiving a stabilization device such as a rod, a cable or a cord. The attachment boss  34  further has a threaded portion  76  for receiving a threaded fastener, such as a set screw, which can be tightened directly or indirectly (e.g., through a spacer) against the stabilization device to retain it in the slot  35 . Any other suitable connectors for securing stabilization devices can be used instead of the attachment bosses  34  to achieve the desired performance. 
         [0019]      FIG. 3  shows an exploded view of the variable geometry occipital fixation device  10  of  FIG. 1 . The first lateral member  12  includes the attachment bore  22 , a pivot bore  36  located at the proximal end  18 , and a fixation bore  38  interposed between the attachment bore  22  and the pivot bore  36 . A groove  40  is interposed between the proximal end  18  and the distal end  20 . The groove  40  facilitates bending of the first lateral member  12  so that it conforms to the occiput. In the embodiment shown in  FIG. 3 , the groove  40  is located on a top surface  42 . The groove  40  could alternatively be located in any other suitable area. Alternatively, the first lateral member  12  could have more than one groove  40 , or no groove at all. 
         [0020]    Similarly, the second lateral member  14  includes a pivot bore  44  located at the proximal end  24 , the attachment bore  28  located at the distal end  26 , and a fixation bore  46  interposed between the attachment bore  28  and the pivot bore  44 . A groove  48  is interposed between the proximal end  24  and the distal end  26  and is located on a top surface  50 . Alternatively, the groove  48  could be located in some other suitable area. The second lateral member  14  could include any appropriate number of grooves  48 . 
         [0021]    The midline member  16  includes a proximal end  30  and a distal end  32 . A pivot bore  52  is located at the proximal end  30  and a fixation bore  54  is located at the distal end  32 . A groove  56  is interposed between the proximal end  30  and the distal end  32  and is located on a top surface  58 . The midline member  16  could include any appropriate number of grooves  56  located in any suitable area. 
         [0022]    In the embodiment shown in  FIGS. 1-3 , the pivot bores  36 ,  44 , and  52  are aligned so that the first lateral member  12  and the second lateral member  14  rotate around a common axis  60 . The thickness  62  of the proximal end  18  of the first lateral member  12  is less than the thickness  64  of the distal end  20 . Similarly, the thickness  66  of the proximal end  24  of the second lateral member  14  is less than the thickness  68  of the distal end  26 . The thickness  70  of the proximal end  30  of the midline member  16  is also less than the thickness  72  of the distal end  32 . In this manner, when the three members  12 ,  14 , and  16  are assembled together and installed in the patient  4 , the thickness of the occipital device  10  is substantially uniform across the members  12 ,  14 , and  16  and the stacked portions of members  12 ,  14 , and  16 . However, the invention is not limited to a device of such uniform thickness. The thicknesses  64 ,  68 , and  72  need not be less than the thicknesses  66 ,  70 , and  74  or be less by the same amounts as in this illustrative embodiment of the invention. 
         [0023]    In the embodiment shown in  FIGS. 1-3 , the fixation bore  38  in the first lateral member  12  is countersunk so that when a fastener (not shown) is inserted into fixation bore  38 , the height of the fastener protruding above the top surface  42  is minimized. The fixation bores  46  and  54  in the second lateral member  14  and the midline member  16  are also countersunk in a similar manner. Alternatively, some or all of the fixation bores  38 ,  46 , and  54  need not be countersunk. 
         [0024]    The three members  12 ,  14 , and  16  can be attached to each other in a number of ways. In one embodiment of the invention, the members are swaged together so that they remain attached to each other while being handled but can be manipulated into different angular relationships to each other. Alternatively, the three members  12 ,  14 , and  16  can remain separate until implantation into the patient  4 , when they become linked to one another by the insertion of a fastener (not shown) into the pivot bores  36 ,  44 , and  52 . The fastener could be a rivet, screw, or any other suitable fastener. 
         [0025]      FIG. 4  is a perspective and partially exploded view of the variable geometry occipital fixation device  10  of  FIG. 1  after insertion of the attachment bosses  34  into attachment bores  22  and  28 . In the embodiment shown in  FIG. 4 , the attachment bosses  34  are inserted into the attachment bores  22  and  28 . The attachment bosses  34  could be press-fit, riveted or swaged into the attachment bores  22  and  28  or inserted in any other suitable manner. The attachment bosses  34  preferably are free to rotate inside of the bores  22  and  28  so as to maintain the orientation of the stabilization device after the orientations of the lateral members  12  and  14  are adjusted. 
         [0026]      FIG. 5A  shows a top plan view of the variable geometry occipital fixation device  10  shown in a narrow configuration. As shown in  FIG. 5A , the angle  78  between the lateral members  12  and  14  is relatively small, thereby reducing the distance  80  between the bosses  34 . The angle  78  can vary as needed achieve the desired distance  80 . 
         [0027]      FIG. 5B  shows a top plan view of the variable geometry occipital fixation device  10  shown in a wide configuration. As shown in  FIG. 5B , the angle  78  between the lateral members  12  and  14  is larger than the angle  78  shown in  FIG. 5A , thereby spanning a larger distance  80  between the bosses  34  than shown in  FIG. 5A . In one embodiment of the present invention, the angle  78  is approximately 100 degrees when the distance  80  is minimized and is approximately 170 degrees when the distance  80  is maximized. The available range for angle  80  need not be limited to these angles, but instead can include any desirable range. 
         [0028]    The first and second lateral members  12  and  14  and the midline member  16  can include any configuration of fixation bores, attachment bores, and pivot bores suitable for achieving the desired variability in the distance  78  between the attachment bores  24  and  38 . The number and the location of the fixation bores, attachment bores, and pivot bores can vary as needed. 
         [0029]      FIG. 6  shows an exemplary method  200  of using the occipital fixation bracket  10  of the present invention. A first lateral member  12  and a first attachment boss  34  are provided (block  205 ). Then, a second lateral member  14  and a second attachment boss  34  are provided (block  210 ). The attachment bosses  34  are preferably inserted into the first and second lateral members  12  and  14  prior to surgery. A midline section  16  is also provided (block  215 ). 
         [0030]    The second lateral member  14  is positioned in the desired location against the occiput (block  220 ). The first lateral member  12  is positioned against the occiput and overlying the second lateral member  14  so that the pivot bores  36  and  44  rotate around a common axis  60  (block  225 ). The midline member  16  is then positioned against the occiput and overlying the first lateral member  12  (block  230 ). The pivot bore  52  is aligned with the pivot bores  36  and  44 , 
         [0031]    Next, fasteners are inserted through the pivot bore  52  and the fixation bore  54  of the midline member  16  and into the occiput, thereby attaching the midline member  16  to the occiput (block  235 ). The first lateral member  12  and the second lateral member  14  are rotated around the common axis  60  until the desired distance  80  between the attachment bosses  34  is achieved (block  240 ). The attachment bosses  34  are free to rotate in their bores  22  and  28 . The fasteners are then inserted into the fixation bores  38  and  46  of the first and second lateral members  12  and  14 , thereby fastening them to the occiput and fixing the position of the attachment bosses  34  (blocks  245  and  250 ). In this manner, the variable geometry occipital fixation device may be installed and adjusted to accommodate a variety of patient sizes and anatomy. 
         [0032]    Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.
A fixation device for connecting a stabilization device to a bone comprises a first member comprising a first portion for attachment to a bone; a second member comprising a second portion for attachment to a bone and connected to the first member by a pivotal connection such that the first and second portions are spaced apart by an adjustable distance, at least one of the first and second members further comprising a portion for mounting a connector adapted to secure a stabilization device.