Abstract:
What is provided is a fixation system that offers a strong and stable construct for maximum fusion augmentation and yet is versatile enough for any patient and is easy to use. Disclosed is a connection assembly for connecting a spinal implant, the assembly comprising: a body, the body including a body opening for receiving at least a portion of a first connector; a swivel having first and second ends and being operatively connected to the body, the first end including a swivel opening for receiving at least a portion of a second connector; a locking plate having an arm at least partially extending into the body opening; a locking unit operatively connected to the body and contacting the second end of the swivel; and whereby activation of the locking unit causes the arm to engage the first connector and swivel opening to engage the second connector thereby preventing relative rotation between the first and second connectors.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of U.S. patent application Ser. No. 11/350,972, filed Feb. 8, 2006 (issuing as U.S. Pat. No. 7,896,905 on Mar. 1, 2011), which application was a non-provisional of US Provisional Patent Application Ser. No. 60/651,314, filed Feb. 9, 2005. 
         [0002]    Each of these applications are incorporated herein by reference. Priority of each of these applications is hereby claimed. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0003]    Not applicable 
       REFERENCE TO A “MICROFICHE APPENDIX” 
       [0004]    Not applicable 
       BACKGROUND 
       [0005]    The present invention relates to surgical systems and more particularly relates to an improved bone or spinal fixation apparatus in the form of a strong and stable construct for maximum fusion augmentation with improved versatility and ease of use, and including an improved rotation and adjustment system. 
         [0006]    There are a number of surgical procedures which require a fixation of portions of the spine with respect to one another. Typically, bone screws are employed in the fixation of the spine. The implantation of bone screws is a surgical procedure which involves the formation of one or more surgical openings in adjacent portions of the spine, with threaded bone screws being implanted into these surgical openings. Connective structure such as rods or plates extend between the various spine members by connecting the adjacent bone screws. 
         [0007]    An early spinal fixation system can be seen in the Lumb et al. U.S. Pat. No. 3,648,691 entitled “Method of Applying Vertebral Appliance”. In the Lumb patent, a method of applying a vertebral appliance for use in bridging one or more diseased or damaged vertebra uses a pair of elongated flexible multiple apertured plates having fasteners which are used to clamp the plate to opposite sides of the spinous processes being spanned. Each strap or plate is of a length adapted to span at least two spinous processes and project there beyond each end so that the fasteners can be passed both behind and in front thereof as well as through the interspinous gap there between. The apertures are located considerably closer together than adjacent processes and they are fastened to the latter in position such that at least one opening registers with each one to receive a growth or soft bony tissue that eventually extrudes therein. 
         [0008]    The Edwards U.S. Pat. No. 4,369,769 shows a spinal fixation system using elongated rods used to bridge across various portions of the spine. In the Edwards &#39;769 patent a spinal fixation device is provided in which sleeves or spacers are placed over and around spinal rods in order to obtain a better reduction of spinal fractures or spinal deformities. These sleeves can be made in various thicknesses so that the surgeon can obtain optimum fixation in each case. The sleeves are made of any biologically compatible material. 
         [0009]    Use of bone screws and connecting rods is also seen in the Ulrich et al. U.S. Pat. No. 4,433,677 entitled “Implantable Splint for Correction Lumbosacral Spondylodesis”. In the Ulrich patent a spinal distraction splint has two like anchor screws extending along respective longitudinal screw axes and adapted to be anchored in the pelvis with the axes crossing. Each of the screws has a head formed with a transverse open recess centered on respective transverse axis and with an angular array of teeth centered on and angularly spaced about the respective transverse axis. 
         [0010]    Another patent that shows screws as part of a spinal stabilizer is the Stephens et al. U.S. Pat. No. 4,604,995. In the Stephens patent a surgical implant is used for imparting stability to the thoraco-lumbar spine by fixation of the implant to the spine with segmental spinal instrumentation. The implant comprises a unitary rod having a generally rectangular configuration formed by a pair of spaced apart branches, mirror image duplicated of one another and equally spaced apart along their length. 
         [0011]    The Steffee U.S. Pat. No. 4,611,581 entitled “Apparatus for Straightening Spinal Columns” provides an apparatus to reduce the extent of displacement between adjacent vertebra in a person&#39;s spinal column and to subsequently maintain the vertebra in a reduced displacement relationship. When the apparatus is to be installed, holes are formed in the displaced vertebra and in vertebra on opposite sides of the displaced vertebra. Force transmitting members are mounted in the holes in the vertebra. A spinal plate is then positioned on the spinal column with the force transmitting members extending outwardly through the slots in the spinal plate. Nuts are tightened on the force transmitting members connected with vertebra on opposite sides of the displaced vertebra to anchor the spinal plate in place. A nut on the force transmitting member connected with the displaced vertebra is then tightened to pull the displaced vertebra to a desired position. In one embodiment, the force transmitting member has a relatively large diameter helix which engages a side wall of the hole in the displaced vertebra. In another embodiment, an insert is positioned in a hole in the displaced vertebra and expanded by the force transmitting member to securely grip the vertebra. 
         [0012]    A device which uses clamps as opposed to bone screws is the Asher U.S. Pat. No. 4,773,402 entitled “Dorsal Transacral Surgical Implant” wherein a pair of spine engageable rods, contoured to the desired spinal column configuration are provided with a yoke and foot element being attached to the pair of rods during use. 
         [0013]    The Sherman U.S. Pat. No. 4,887,596 shows a pedicle screw for use in internal fixation of the spine comprising a shaft threaded at one end for insertion into a bone and at the other end having a yoke for receiving a rod, the yoke having a cusp adapted to bear against the rod and clamps for holding the rod against the cusp while permitting adjustment of the angle between the rod and the yoke. 
         [0014]    Each of the above referenced patents are incorporated herein by reference. 
         [0015]    One of the problems with the application of a spinal fixation system is the limited adjustability of the connective structures with respect to a plurality of spaced apart bone screws which had been placed in the spine at various angles. 
         [0016]    Another problem with the application of a spinal fixation system is the ease with which the surgeon will install the clamping systems. 
         [0017]    While certain novel features of this invention shown and described below are pointed out in the annexed claims, the invention is not intended to be limited to the details specified, since a person of ordinary skill in the relevant art will understand that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation may be made without departing in any way from the spirit of the present invention. No feature of the invention is critical or essential unless it is expressly stated as being “critical” or “essential.” 
       BRIEF SUMMARY 
       [0018]    The apparatus of the present invention solves the problems confronted in the art in a simple and straightforward manner. What is provided is a fixation system that offers a strong and stable construct for maximum fusion augmentation and yet is versatile enough for any patient and is easy to use. 
         [0019]    In one embodiment is provided an improved spinal fixation apparatus having improved fit through relative adjustments between the screws and rods. 
         [0020]    The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0021]    For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
           [0022]      FIG. 1  is an exploded perspective view of one embodiment of a preferred clamp; 
           [0023]      FIG. 1A  is an enlarged perspective view of a retainer; 
           [0024]      FIG. 2  is an exploded perspective view of the clamp of  FIG. 1 , but taken from the opposite side as that shown in  FIG. 1 ; 
           [0025]      FIG. 3  is a perspective view of the clamp of  FIG. 1  showing arrows schematically indicating various adjustments which can be made; 
           [0026]      FIG. 4  is a top view of the clamp of  FIG. 1  with set screw removed; 
           [0027]      FIG. 5  is a perspective view of a two vertebrae to be fused using the clamp of  FIG. 1A  and shown a plurality of screws installed in the vertebrae (shown from the rear of a person&#39;s body); 
           [0028]      FIG. 6  is a perspective view of the two vertebrae of  FIG. 5  where two sets of clamps are being placed on the plurality of screws (shown from the rear of a person&#39;s body); 
           [0029]      FIG. 7  shows the two vertebrae of  FIGS. 5 and 6  with the clamps being locked in position (shown from the rear of a person&#39;s body). 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Detailed descriptions of one or more preferred embodiments are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in any appropriate system, structure or manner. 
         [0031]      FIGS. 5-7  illustrate the process of fusing two vertebrae  800 ,  810  using a plurality of clamps  10 A,  10 B,  10 C, and  10 D of the construction shown in  FIGS. 1-4 . All clamps  10  can be of substantially identical construction (however, clamps  10 A, 10 B are shown as mirror images of clamps  10 C,  10 D to have both rods  80 A,  80 B set between the clamps). The operation of clamp  10 A will be described in specific detail. In each case, for an effective fusion, vertebra  800  is held in contact with vertebra  810 . In its simplest form, clamp  10 A can be mechanically connected to vertebra  810  and a second clamp  10 B can be mechanically connected to vertebra  800 . This mechanical connection can be achieved by means of screws  20  or other fasteners which are compatible with vertebrae and the human body and installed by a driver  24 . Clamp  10 A and  10 B can be mechanically connected to each other by rod  80 A. On the opposite side of vertebrae  800 , 810  a second set of clamps  10 C, 10 D and rod  80 B can be used to mechanically connect vertebrae  800 , 810 . These two clamps can be placed over screws  20 C,  20 D as schematically indicated by arrows  28 ,  27 . A driver  24  can be used to mechanically lock each clamp through tightening of the clamp&#39;s set screw by turning in the direction of arrow  26 . The two rods  80 A, 80 B can be mechanically connected to each other for additional support. Over a period of time, after being mechanically connected, the bone in vertebrae  800 , 810  will grow or fuse together thus completing the fusion. 
         [0032]      FIGS. 1 and 2  are exploded views of a preferred clamp  10  (showing two examples of the clamp  10 A, 10 B). Although constructed similar to each other the individual components of clamp  10 A and clamp  10 B will be differentiated by the addition of an “A” or a “B.” Clamp  10  can be used to mechanically connect bone screws  20  with rods  80 . Clamp  10  can comprise body  130 , locking plate  120 , rod disc  110 , and swivel  100 . Set screw  150  and retainer  140  can be used to lock in place swivel  100 , rod clamp  110 , and locking plate  120  (which can be assembled in the direction of arrow  815  as shown in  FIG. 1 ). Alternatively, set screw  150  can be used by itself without retainer  140 . Screw  20  can be connected to body  130  through bore  540 . Rod  80  can be connected to body  130  through opening  210 . The mechanics of the connections with rod  80  and screw  20  will be described below. 
         [0033]    During installation each clamp  10  preferably is adjustable in various directions with respect to rod  80  and screw  20  (as schematically indicated by  FIG. 3 ).  FIG. 3  shows clamp  10  having screw  20  and rod  80  mounted. Because of variations when inserting screw  20  in a specific vertebra, clamp  10  is provided with various adjustment options related to screw  10 . For screw  20  the two principal adjustment options are indicated by arrows  840 , 850 . The longitudinal axis of screw  20  is shown parallel to arrow  840 . Rod  80  is shown being parallel to arrow  820 . When clamp  10  is not tightened body  130  can slide relative to screw  20  in both directions indicated by arrow  840 . Also when clamp  10  is not locked, body  130  can rotate relative to screw  20  in both directions indicated by arrow  850 . 
         [0034]    For rod  80  the three principal adjustment options are indicated be arrows  820 ,  860 ,  870 . When clamp  10  is not locked, rod  80  can slide relative to body  130  in both directions indicated by arrow  820 . Additionally, when not locked, rod  80  can rotate relative to body  130  in both directions indicated by arrow  870  and both directions indicated by arrow  860 . 
         [0035]    The above described possible relative movements between rod  80  and body  130  along with the relative movements between body  130  and screw  20  provide adjustability between rod  80  and screw  20 . The relative movement between rod  80  and screw  20  facilitates fixation of two or more clamp  10  members regardless of the relative positions (angular, height, location) of respective screws  20 . For example, as shown in  FIGS. 5-7 , clamps  10 A, 10 B can be connected to rod  80 A even where screws  20 A, 20 B are not parallel to each other and are not at the same relative height. 
         [0036]      FIG. 4  is a top view of a portion of clamp  10  showing rod  80  inserted into opening  210  of swivel  100  and swivel  100  inserted into rod disc  110 . Rod  80  can sit in recess  310 .  FIG. 3  is a perspective view of clamp  10  showing bone screw  20  inserted into bore  540  of body  130  with locking plate  120  lying on top of body  130 .  FIGS. 3 and 4  illustrate how arm  440  of locking plate  120  enters opening  530  of body  130  to engage bone screw  20 . Also shown is tapped bore  510  wherein set screw  150  enters to lock clamp  10 . 
         [0037]    Below the individual components of clamp  10  (including body  130 , locking plate  120 , rod disc  110 , and swivel  100 ) will be described in specific detail. 
         [0038]    Swivel  100  can comprise base  240 , shaft  230 , mid portion  220 , and head  200 . Base  240  can be circular and include beveled or angled edge  250  and bottom  260 . Beveled or angled edge  250  can be used as the contact point of set screw  150  (when set screw  150  is tightened in the direction of arrow  890 , swivel  100  is pulled in the direction of arrow  880  thereby locking clamp  10 —see  FIG. 3 ). The top of head  200  can have a rectangular cross section with rounded edges. Shaft  230  can include a circular cross section which is smaller than base  240 . Mid portion  220  can include a circular cross section which is larger than shaft  230 . Head  200  can include opening  210 , face  270 , and a plurality of edges  272 , 274 . 
         [0039]    Rod disc  110  can include top  300  and bottom  340 . On bottom  340  can include a plurality of teeth  350 . Recess  310  can be included on top  300 . First bore  320  can pass from top  300  to bottom. Second bore  330  can be included which starts at the top but stops before hitting the bottom. First bore  320  can be circular. Second bore  330  is preferably a non-circular shape to restrict relative rotation between rod disc  110  and swivel  100  (head  200  of swivel  100  can seat in second bore  330 ). Second bore  300  can operatively connect with head  200  of swivel  100 . Rod  80  can seat in recess  310  when at least partially inserted in opening  210 . When clamp  10  is locked, rod  80  can be frictionally engaged between opening  210  and recess  310 . Also when clamp  10  is locked, plurality of teeth  350  of rod disc  110  can be engaged with plurality of teeth  420  of locking plate  120  thereby preventing relative rotation between rod disc  110  and locking plate  120 . In a preferred embodiment seventy two teeth are used, but the number can vary based on size and strength considerations. Using sixty teeth  420  provide positioning approximately every six degrees while seventy two teeth  420  provide positioning approximately every five degrees. 
         [0040]    Locking plate  120  can include arm  440  and bore  410 . Arm  440  can include cup  450  which includes plurality of ribs  452 . Plurality of ribs  452  can be used to prevent relative rotation between bone screw  20  and arm  440  (and also body  130 ). When arm  440  of locking plate  120  enters opening  530  of body  130 , relative rotation between locking plate  120  and body  130  is restricted. 
         [0041]    Body  130  can include transverse bore  500  for insertion of base  240  of swivel  100 . Longitudinal bore  540  can be included for receiving screw  20 . Longitudinal bore  540  can include plurality of ribs  570 . Plurality of ribs  452  can be used to prevent relative rotation between bone screw  20  and body  130 . Plurality of ribs  452  can be placed on only a radial portion of longitudinal bore  540  (and not around the complete radius of bore  540 ). Recessed area  520  can be included to receive locking plate  120 . Opening  530  can be included to receive arm  440  of locking plate  120 . Body  130  can include threads  550  in tapped bore  510 . At the base of tapped bore  510  can be included bore  590  and edge  560 . 
         [0042]      FIG. 1A  shows an enlarged perspective view of retainer  140 . Retainer  140  can include top  600 , shaft  610 , first edge  620 , second edge  630 , curved surface  640 , and bottom  650 . Shaft  610  can be inserted in bore  590  of body  130  (see FIGS.  1 , 2 , and  4 ). Retainer  140  can be used to provide support for set screw  150 , when set screw  150  is contacting base  240  of swivel  100 . Shaft  610  of retainer  140  can be press fit into bore  590  as a means for retaining swivel  100  in body  130  when set screw  150  is not tightened. When press fit into body  130 , first edge  620  of retainer  140  can operatively engage beveled edge  250  of swivel  100  thereby preventing swivel  100  from being removed complete from bore  500  of body  130 . Retainer  140  can be used to prevent the various pieces of clamp  10  from coming apart during use and possibly being lost in a patient. However, swivel  100  preferably has enough play that swivel  100  along with rod disc  110  can rotate relative to locking plate  120  and body  130 . Alternatively, retainer  140  can be connected to body  130  in various ways, such as welding, adhesives, along with other conventionally available connection methods. 
         [0043]    Set screw  150  can include top  700 , angled tip  715 , threads  720 , and star socket  710 . Set screw  150  can be threaded into tapped bore  510  of body  130 . Other means of tightening set screw  150  besides star socket  710  can be used, such as a phillips head; flat head; bolt head, allen wrench head. 
         [0044]    Screw  20  can include shank  30  and course threaded portion  40 . For tightening screw  20  can also include star socket  70 . Other means of tightening screw  20  besides star socket  70  can be used, such as a phillips head; flat head; bolt head, allen wrench head. 
         [0045]    Rod  80  can be a shaft and include a circular cross section. 
         [0046]    The locking mechanism of clamp  10  will now be described. Clamp  10  can comprise body  130 , locking plate  120 , rod disc  110 , and swivel  100 . Set screw  150  can be used to lock in place swivel  100 , rod clamp  110 , and locking plate  120 . Rod  80  can be connected to body  130  through opening  210  of swivel  100 . Bone screw  20  can be connected to body  130  through bore  540 . Before set screw  150  is tightened (locking clamp  10 ) both rod  80  and bone screw  20  can be adjusted in all directions as described in the discussion of  FIG. 3 . However, after set screw  150  is used to lock clamp  10 , both rod  80  and screw  20  will be held firmly in place. 
         [0047]    To assemble clamp  10 , base  240  of swivel is placed through first bore  320  of rod disc  110 , through bore  410  of locking plate  120 , and then through bore  500  of body  130 . Arm  440  of locking plate  120  enters opening  530  of body  130 , thereby preventing relative rotation between body  130  and locking plate  120 . Plurality of teeth  420  of locking plate  120  are facing plurality of teeth  350  of rod disc  110 , however, when clamp  10  is not locked these two sets of teeth do not engage each other and rod disc  110  can rotate relative to locking plate  120 . When locked these two sets of teeth engage each other preventing relative rotation. Part of head  200  of swivel  100  sits in second bore  330  of rod disc  110  and head  200  will rotate with rod disc  110 . Recess  310  of rod disc  110  preferably is aligned with opening  210  of swivel  100 . Such alignment will allow rod  80  to at least be partially inserted in opening  210  and rest in recess  310 . Recess  310  preferably confirms with the shape of rod  80 . 
         [0048]    Rod  80  can be at least partially inserted into opening  210  of swivel  100 . Bone screw can be inserted at least partially into bore  540  of body  130 . When clamp  10  is not locked, rod  80  can slide relative to opening  210  (and therefore relative to clamp  10 ). Also when not locked rod  80  can rotate relative to clamp  10  because swivel  100  and rod disc  110  can rotate relative to body  130 . When not locked screw  20  can slide relative to body  130  (and therefore relative to clamp  10 ). Also when not locked screw  20  can rotate inside of bore  540  of body  130 . 
         [0049]    To lock clamp  10 , set screw  150  can be threaded into tapped bore  510 . Tip  715  of set screw  150  will contact base  240  of swivel  100  causing swivel  100  to be pulled further into bore  500  of body  130 . Pulling swivel  100  into body  130  causes plurality of teeth  420  of locking plate  120  to engage plurality of teeth  350  of rod disc  110  thereby preventing relative rotation between rod disc  110  and locking plate  120 . Because locking plate  120  is restricted from rotating relative to body  130  (via arm  440  of locking plate  120  being at least partially inserted in opening  530  of body  130 ) rod disc  110  will also be restricted from so rotating. Head  200  of swivel  100  at least partially seating in second bore  330  of rod disc  110  also prevents relative rotation of swivel  100  in relation to body  130 . Swivel  100  being pulled inside of body  130  also causes rod  80  to be frictionally engaged between bore  210  of swivel  100  and recess  310  of rod disc  110 . In effect rod  80  is squeezed between rod disc  110  and bore  210 . When frictionally engaged rod  80  is restricted from moving relative to body  130  in all manners (e.g., sliding or rotating). Swivel  100  being pulled further into bore  500  of body  130  causes bore  210  to pull on rod  80 , rod  80  then pushes on rod disc  110 , rod disc  100  then pushes on locking plate  120 , arm  440  of locking plate  120  then pushes through opening  530  on screw  20 . Screw  20  is thereby frictionally engaged between arm  440  of locking plate  120  and bore  540  of body  130 . When frictionally engaged screw  20  is restricted from moving relative to body  130  in all manners (e.g., sliding or rotating). In such manner both rod  80  and screw  20  can be securely held in clamp  10 . 
         [0050]    A single version clamp  10  has been disclosed. Preferably, both left and right hand versions of clamp  10  will be used on the left and right hand sides of a fusion. Persons of ordinary skill in the art will understand the mechanics of making left and right hand versions of clamp  10 .  FIGS. 6 and 7  show left and right hand versions of clamps  10 . Clamps  10 A and  10 B are left hand versions and clamps  10 C and  10 D are right hand versions. Left and right hand versions are used to have a symmetry between positioning of screws  20  and heads  100  of swivels  100 . If only a single version of clamp  10  was used the clamps  10  used on the left hand side would appear to be offset from the clamps used on the right hand side. An alternative method of allowing a single clamp  10  to be used as both a left and right hand version is to have tapped bore  510  extend completely through body  130 . To switch from the left to right hand version in this alternative embodiment, set screw  150  is switched from entering tapped bore  510  on opposite sides. 
         [0051]    The following is a list of reference numerals: 
         [0000]    
       
         
               
             
               
               
             
               
               
             
           
               
                   
               
               
                 LIST FOR REFERENCE NUMERALS 
               
             
          
           
               
                 (Part No.) 
                 (Description) 
               
               
                   
               
             
          
           
               
                 10 
                 clamp 
               
               
                 20 
                 screw 
               
               
                 24 
                 driver 
               
               
                 26 
                 arrow 
               
               
                 27 
                 arrow 
               
               
                 28 
                 arrow 
               
               
                 30 
                 shank 
               
               
                 32 
                 ribs 
               
               
                 40 
                 coarse thread 
               
               
                 50 
                 fine thread 
               
               
                 60 
                 mid portion 
               
               
                 70 
                 star socket 
               
               
                 80 
                 rod 
               
               
                 100 
                 swivel 
               
               
                 110 
                 rod disc 
               
               
                 120 
                 locking plate 
               
               
                 130 
                 body 
               
               
                 140 
                 retainer 
               
               
                 150 
                 set screw 
               
               
                 200 
                 head 
               
               
                 210 
                 opening 
               
               
                 220 
                 mid-portion 
               
               
                 230 
                 shaft 
               
               
                 240 
                 base 
               
               
                 250 
                 beveled edge 
               
               
                 260 
                 bottom 
               
               
                 270 
                 face 
               
               
                 272 
                 edge 
               
               
                 274 
                 edge 
               
               
                 300 
                 top 
               
               
                 310 
                 recess 
               
               
                 320 
                 first bore 
               
               
                 330 
                 second bore 
               
               
                 340 
                 bottom 
               
               
                 350 
                 plurality of teeth 
               
               
                 400 
                 top 
               
               
                 410 
                 bore 
               
               
                 420 
                 plurality of teeth 
               
               
                 430 
                 edge portion 
               
               
                 440 
                 arm 
               
               
                 450 
                 cup 
               
               
                 452 
                 plurality of ribs 
               
               
                 453 
                 angle 
               
               
                 454 
                 angle 
               
               
                 460 
                 bottom 
               
               
                 500 
                 bore 
               
               
                 510 
                 tapped bore 
               
               
                 520 
                 recessed area 
               
               
                 530 
                 opening 
               
               
                 540 
                 bore 
               
               
                 550 
                 threads 
               
               
                 560 
                 edge 
               
               
                 570 
                 plurality of ribs 
               
               
                 580 
                 angle 
               
               
                 590 
                 bore 
               
               
                 600 
                 top 
               
               
                 610 
                 shaft 
               
               
                 620 
                 first edge 
               
               
                 630 
                 second edge 
               
               
                 640 
                 curved surface 
               
               
                 650 
                 bottom 
               
               
                 700 
                 top 
               
               
                 710 
                 star socket 
               
               
                 715 
                 tip 
               
               
                 718 
                 point 
               
               
                 720 
                 threads 
               
               
                 800 
                 vertebra 
               
               
                 810 
                 vertebra 
               
               
                 815 
                 arrow 
               
               
                 820 
                 arrow 
               
               
                 830 
                 arrow 
               
               
                 840 
                 arrow 
               
               
                 850 
                 arrow 
               
               
                 860 
                 arrow 
               
               
                 870 
                 arrow 
               
               
                 880 
                 arrow 
               
               
                 890 
                 arrow 
               
               
                   
               
             
          
         
       
     
         [0052]    All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise. The components of the clamp  10  are preferably constructed from titanium grade 6AL-4VELI which is a standard medical grade of titanium. The type and heat treatment of material can be determined by those of ordinary skill in the art based on the stress and forces encountered by the individual components. However, other materials can be used which are compatible with the body. For example surgical steel can be used along with polymers of sufficient strength. 
         [0053]    It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention set forth in the appended claims. The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.