Abstract:
A surgical system for stabilizing a first bone segment to a second bone segment, the system comprising a plate having a first end and a second end, wherein the first end is configured to be secured to the first bone segment and the second end is configured to be secured to the second bone segment, and further wherein the plate has a structural integrity sufficient to stabilize the first bone segment to the second bone segment. Further embodiments comprise a supplemental plate for stabilizing a third bone segment to the second bone segment.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATIONS 
     This patent application: 
     (1) is a continuation-in-part of pending prior U.S. patent application Ser. No. 10/554,379, filed Oct. 25, 2005 by Barry T. Bickley et al. for FIXATION AUGMENTATION DEVICE AND RELATED TECHNIQUES, which:
         (a) claims benefit of International (PCT) Patent Application No. PCT/US04/14640, filed May 10, 2004 for FIXATION AUGMENTATION DEVICE AND RELATED TECHNIQUES, which itself claims benefit of U.S. Provisional Patent Application Ser. No. 60/468,829, filed May 8, 2003 for FIXATION AUGMENTATION DEVICE; and   (b) is a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 10/246,304, filed Sep. 18, 2002 for FIXATION AUGMENTATION DEVICE AND RELATED TECHNIQUES;       

     (2) is a continuation-in-part of pending prior U.S. patent application Ser. No. 12/148,845, filed Apr. 23, 2008 by Barry T. Bickley et al. for METHOD AND APPARATUS FOR SECURING AN OBJECT TO BONE; and 
     (3) claims benefit of prior U.S. Provisional Patent Application Ser. No. 60/932,805, filed Jun. 1, 2007 by Barry T. Bickley et al. for METHOD AND APPARATUS FOR STABILIZING BONE. 
     The six above-identified patent applications are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to surgical methods and apparatus in general, and more particularly to surgical methods and apparatus for securing an object to bone and/or for stabilizing bone. 
     BACKGROUND OF THE INVENTION 
     In many situations an object may need to be secured to bone. By way of example but not limitation, where a bone is fractured, it may be desirable to stabilize the bone with a bone plate which extends across the fracture line. By way of further example but not limitation, where two separate bones need to be secured together (e.g., in the case of a spinal fusion), it may be desirable to secure the two bones to one another with a bone plate which extends from one bone to the other. By way of still further example but not limitation, where soft tissue needs to be attached (or re-attached) to bone (e.g., in the case of a ligament repair or reconstruction), it may be desirable to capture the soft tissue to the bone using a fixation plate. 
     In all of the foregoing situations, as well as many others which are well known to those skilled in the art, a plate or other object needs to be secured to bone. Such attachment is most commonly effected by using a surgical screw which passes through a hole in the plate (or other object) and into the bone. 
     When using a surgical screw to secure a plate to bone, the plate is first aligned with the bone. Then a hole is drilled into the bone, by passing a drill through a pre-existing hole in the plate and into the bone. Next, the bone hole may be tapped. Then the surgical screw is passed through the hole in the plate and into the hole in the bone, whereby to secure the plate to the bone. 
     One problem which can arise during the foregoing procedure is that the hole in the bone may become stripped as the screw is inserted into the bone. When this occurs, the screw can no longer obtain adequate purchase in the bone, thereby undermining plate fixation. A screw having inadequate purchase is sometimes referred to as a “spinner”. Spinners can occur for many reasons, including (i) inadequate bone quality, (ii) over-tightening of the screw, (iii) an error when drilling the hole in the bone, (iv) an error when tapping the hole in the bone, etc. As noted above, spinners generally result in inadequate fixation. 
     SUMMARY OF THE INVENTION 
     The present invention is intended to address the foregoing deficiencies of the prior art, by providing a new and improved method and apparatus for securing an object to bone and/or for stabilizing bone. 
     More particularly, the present invention provides a new and improved fixation system for securing an object to bone and/or for stabilizing bone. 
     In one preferred form of the present invention, the new fixation system comprises a plate which is to be secured to bone, and a sleeve and a screw for securing the plate to the bone. The plate comprises an opening which extends through the plate. The plate is placed against the bone and then a drill is used to form a hole in the bone beneath the opening. A sleeve is passed through the opening and into the hole in the bone. The sleeve and plate are formed so that the sleeve (and the recipient bone hole) can be disposed at any one of a variety of angles relative to the plate. A screw is then passed through the sleeve, radially expanding the sleeve so that the sleeve is simultaneously secured to both the bone and the plate. 
     In another preferred form of the present invention, the new fixation system is intended to stabilize bone in general, and vertebral bodies in particular. 
     In a preferred form of the present invention, there is provided a novel anterior cervical plate (ACP) system which comprises a novel ACP which is to be attached to two adjacent cervical bodies, and attachment apparatus for attaching the ACP to the two cervical bodies. Preferably, the attachment apparatus comprise a screw and, in one preferred form of the invention, the attachment apparatus comprise a sleeve and screw combination, where the sleeve acts as an interface between (i) the bone and the screw, and (ii) the ACP and the screw, with the sleeve enhancing fixation. Among other things, the ACP is specifically configured to provide the option of adding future level extensions. 
     In another form of the present invention, there is provided a surgical system for stabilizing a first bone segment to a second bone segment, the system comprising: 
     a plate having a first end and a second end, wherein the first end is configured to be secured to the first bone segment and the second end is configured to be secured to the second bone segment, and further wherein the plate has a structural integrity sufficient to stabilize the first bone segment to the second bone segment; 
     the plate comprising a first, generally toroidal body at the first end of the plate, a second generally toroidal body at the second end of the plate, and a bridge connecting the first generally toroidal body to the second generally toroidal body; 
     the first generally toroidal body comprising at least one opening extending therethrough for receiving attachment apparatus therethrough for securing the first generally toroidal body to the first bone segment, and the second generally toroidal body comprising at least one opening extending therethrough for receiving attachment apparatus therethrough for securing the second generally toroidal body to the second bone segment. 
     If desired, the surgical system may further comprise: 
     a supplemental plate for stabilizing a third bone segment to the second bone segment, the supplemental plate having a first end and a second end, wherein the first end is configured to be secured to the second generally toroidal body of the plate and the second end is configured to be secured to the third bone segment, and further wherein the supplemental plate has a structural integrity sufficient to stabilize the third bone segment to the second bone segment; 
     the supplemental plate comprising a first, generally toroidal body at the first end of the supplemental plate, a second generally toroidal body at the second end of the supplemental plate, and a bridge connecting the first generally toroidal body to the second generally toroidal body; 
     the first generally toroidal body comprising a cavity extending therethrough for mounting on the second generally toroidal body of the plate so as to secure the supplemental plate to the plate, and the second generally toroidal body comprising at least one opening extending therethrough for receiving attachment apparatus therethrough for securing the second generally toroidal body to the third bone segment. 
     In another form of the present invention, there is provided a method for stabilizing a first bone segment to a second bone segment, the method comprising: 
     providing a surgical system comprising:
         a plate having a first end and a second end, wherein the first end is configured to be secured to the first bone segment and the second end is configured to be secured to the second bone segment, and further wherein the plate has a structural integrity sufficient to stabilize the first bone segment to the second bone segment;   the plate comprising a first, generally toroidal body at the first end of the plate, a second generally toroidal body at the second end of the plate, and a bridge connecting the first generally toroidal body to the second generally toroidal body;   the first generally toroidal body comprising at least one opening extending therethrough for receiving attachment apparatus therethrough for securing the first generally toroidal body to the first bone segment, and the second generally toroidal body comprising at least one opening extending therethrough for receiving attachment apparatus therethrough for securing the second generally toroidal body to the second bone segment; and       

     securing the first generally toroidal body to the first bone segment and securing the second generally toroidal body to the second bone segment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be read in conjunction with the attached drawings wherein like numbers refer to like parts, and further wherein: 
         FIG. 1  is a schematic view showing one preferred form of the novel fixation system of the present invention; 
         FIGS. 2 and 3  are schematic views showing one preferred form of the plate; 
         FIG. 4  is a schematic view showing an alternative form of plate and sleeve; 
         FIGS. 5-10  are schematic views showing one preferred form of the sleeve; 
         FIGS. 11-14  are schematic views showing one preferred form of the screw; 
         FIGS. 15-20  are schematic views showing the plate being secured to a bone using a plurality of sleeve/screw constructions; 
         FIGS. 21-25  are schematic views showing another preferred form of the plate; 
         FIGS. 26-28  are schematic views showing another preferred form of the sleeve; 
         FIG. 29  is a schematic view showing another preferred form of the screw; 
         FIG. 30  is a schematic view showing a rod for use with the sleeve/screw construction of the present invention; 
         FIG. 31  is a schematic view showing another form of rod for use with the sleeve/screw construction of the present invention; 
         FIG. 32  is a schematic view of a plate for capturing a rod against bone; 
         FIG. 33  is a schematic view of a “tulip” mount which may be secured to a bone using the sleeve/screw construction of the present invention; 
         FIGS. 34 and 35  show the sleeve being mated with the tulip mount, and the screw being mated with the sleeve, respectively; 
         FIG. 36  is a schematic view showing a hybrid tulip mount/sleeve construction; 
         FIG. 37  is a schematic view showing a screw being mated with the hybrid tulip mount/sleeve construction shown in  FIG. 36 ; 
         FIG. 38  is a schematic top perspective view illustrating (i) a primary anterior cervical plate (ACP) formed in accordance with the present invention, and (ii) a supplemental ACP formed in accordance with the present invention; 
         FIG. 39  is an enlarged schematic top perspective view illustrating the primary ACP shown in  FIG. 38 ; 
         FIG. 40  is an enlarged schematic top perspective view illustrating the supplemental ACP shown in  FIG. 38 ; 
         FIG. 41  is a schematic bottom perspective view illustrating the primary ACP and the supplemental ACP shown in  FIG. 38 ; 
         FIG. 42  is a schematic end perspective view illustrating the primary ACP and the supplemental ACP shown in  FIG. 38 ; 
         FIGS. 43-46  are schematic views of the preferred form of attachment apparatus used to secure the primary ACP and the supplemental ACP to bone; 
         FIG. 47  is a schematic side view showing how a supplemental ACP  700  fits over the primary ACP  600 ; 
         FIGS. 48 and 49  are schematic top views showing how a primary ACP  600  and a supplemental ACP  700  may be oriented “off-axis” to one another; 
         FIGS. 50 and 51  are schematic side views showing how attachment apparatus  635  may pivot relative to primary ACP  600 ; 
         FIG. 52  is a schematic side view showing how attachment apparatus  635  may translate longitudinally relative to primary ACP  600 ; 
         FIG. 53  is a schematic top perspective view illustrating a primary ACP  600  with a protective collar attached; and 
         FIG. 54  is a schematic top perspective view illustrating a supplemental ACP  700  with a protective collar attached. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Method and Apparatus for Securing an Object to Bone 
     Looking first at  FIG. 1 , there is shown a novel fixation system  5  which generally comprises a plate  10  which is to be secured to bone, a sleeve  15  and a screw  20  for securing plate  10  to the bone. 
     Plate  10  is shown in detail in  FIGS. 2 and 3 . Plate  10  generally comprises a distal surface  25  ( FIG. 3 ) for positioning against bone, a proximal surface  30  ( FIG. 2 ), and at least one opening  35  formed in the plate. Opening  35  is preferably in the form of a bore-counterbore configuration, i.e., a bore  40  opens on distal surface  25 , a counterbore  45  opens on proximal surface  30 , and an annular flange  50  is formed at the intersection of bore  40  and counterbore  45 . As will hereinafter be discussed in further detail, bore  40  is sized to receive the shank of sleeve  15 , and counterbore  45  is sized to receive the head of sleeve  15 , with annular flange  50  serving to support the head of sleeve  15  and prevent the head of the sleeve from passing through the plate. 
     Opening  35  is preferably dimensioned, and one or more of the plate surfaces defining opening  35  are preferably appropriately radiused, and counterpart portions of sleeve  15  are preferably appropriately radiused, in order to permit sleeve  15  to extend through plate  10  at a range of different angles as will hereinafter be discussed in further detail. See, for example,  FIG. 1 , where sleeve  15  is shown extending through plate  10  at an acute angle. 
     A raised rim  55  is preferably formed on proximal surface  30  adjacent to opening  35 . Raised rim  55  helps to present a smooth interface between the elements of the system and the surrounding tissue, particularly when sleeve  15  and screw  20  are placed at an acute angle relative to the plane of plate  10  (i.e., at an angle significantly off the perpendicular, such as is shown in  FIG. 1 ). In addition, raised rim  55  also provides an enlarged contact surface for the head of sleeve  15 , particularly when sleeve  15  and screw  20  are placed at an acute angle relative to the plane of plate  10  (i.e., an angle significantly off the perpendicular). See, for example,  FIG. 1 . 
     Depending on the intended use of plate  10 , more than one opening  35  may be provided. By way of example but not limitation, where plate  10  is intended to be used as a fracture fixation plate or as a spinal fusion plate, at least one (and preferably two or more) openings  35  are formed in plate  10  on either side of the bone separation line (e.g., the fracture line, the vertebral body abutment lines, etc.), such that plate  10  can be secured to bone on each side of the bone separation line. By way of further example but not limitation, where plate  10  is intended to be used to secure soft tissue to bone, plate  10  might include only one opening  35 . 
     If desired, opening  35  in plate  10  and head  65  of sleeve  15  may be formed with non-circular (e.g., oval) shapes (as seen in top view) so as to provide an anti-rotation contact between the sleeve and the plate. Furthermore, if desired, opening  35  in plate  10  can have a slot-like configuration (as seen in top view), so as to allow a degree of longitudinal freedom when determining where to place sleeve  15  through opening  35  in plate  10 . See  FIG. 4 . 
     Sleeve  15  is shown in detail in  FIGS. 5-10 . Sleeve  15  generally comprises a shank  60 , a head  65  and an opening  70  extending along the length of sleeve  15 . 
     Shank  60  comprises a screw thread  75  on its outer surface. Screw thread  75  is preferably configured to facilitate the gripping entry of sleeve  15  into bone when the sleeve is turned into bone. Such screw threads may be self-drilling, in which case it may not be necessary to pre-drill a hole in the bone. Furthermore, the threads may be self-tapping, or they may not be self-tapping, in which case it may be necessary to tap a bone hole before inserting the sleeve into that bone hole. Sleeve  15  may be formed with threads having a reverse face so as to aid in backing the sleeve out of the bone, in the event that the same should be desired (e.g., in the case of a revision). 
     A plurality of slits  80  extend through the side wall of shank  60  at the distal end of shank  60 . Slits  80  permit shank  60  to expand radially when screw  20  is disposed in opening  70 , as will hereinafter be discussed in further detail. 
     Head  65  includes a plurality of longitudinally-extending slots  85 . Slots  85  permit sleeve  15  to be held against rotation as screw  20  is turned into the sleeve, as will hereinafter be discussed in further detail. Slots  85  also permit head  65  to expand when screw  20  is turned into the sleeve, whereby to facilitate head  65  gripping adjacent portions of plate  10 , as will hereinafter be discussed in further detail. Additionally, the head of sleeve  15  can be formed with a beveled edge so that it stands less proud when the sleeve is inserted into plate  10  at an angle which is relatively far off the perpendicular. 
     Opening  70  comprises a bore-counterbore-counterbore configuration. More particularly, and looking now at  FIG. 10 , a bore  90 , terminating in a tapered portion  92 , communicates with distal slits  80 . A counterbore  95  communicates with bore  90 . An annular flange  100  is formed at the intersection of bore  90  and counterbore  95 . Another counterbore  102  communicates with counterbore  95  and opens on the proximal end of sleeve  15 . An annular shoulder  103  is formed at the intersection of counterbore  95  and counterbore  102 . As will hereinafter be discussed, counterbore  95  is sized to receive the shank of screw  20 , and counterbore  102  is sized to receive the head of screw  20 , with annular shoulder  103  serving to support the head of screw  20 . However, sleeve  15  and screw  20  are sized so that when screw  20  is received in opening  70  of sleeve  15 , engagement of the shank of screw  20  with tapered portion  92  of sleeve  15  will radially expand the distal end of sleeve  15  so as to grip the bone. Furthermore, sleeve  15  and screw  20  are also sized so that when the head of screw  20  is seated in counterbore  102 , screw  20  will radially expand head  65  of sleeve  15  so as to grip plate  10 . 
     It should be appreciated that (i) the size and shape of the head of screw  20 , (ii) the size and shape of counterbore  102 , and (iii) the size and shape of slots  85  in the head of sleeve  15 , can all be combined so as to “tune” the degree of expansion of head  65  of sleeve  15 , whereby to regulate the force with which the sleeve is secured to plate  10 . 
     In addition to the foregoing, and as will hereinafter be discussed in further detail, sleeve  15  is preferably sized so that, when sleeve  15  is deployed in a plate  10  and into a bone, the distal end of shank  60  will extend beyond the cortical bone/cancellous bone interface, so as to provide enhanced stabilization. 
     Thus, advancing screw  20  into sleeve  15  radially expands both the distal and proximal ends of sleeve  20 , such that the sleeve is simultaneously secured to both the bone and the plate, as will hereinafter be discussed in further detail. 
     Bore  95  is preferably threaded so as to securely receive the shank of screw  20 . 
     A radially-extending detent  105  is preferably formed in the side wall of counterbore  102 , in order to receive a counterpart locking finger (see below) of screw  20 , whereby to releasably lock screw  20  to sleeve  15 , as will hereinafter be discussed in further detail. 
     Screw  20  is shown in detail in  FIGS. 11-14 . Screw  20  generally comprises a shank  110 , a head  115  and an opening  120  extending longitudinally into screw  20 . Shank  110  comprises a thread  125  on its outer surface. As noted above, head  115  includes a radially-extending locking finger  130  for seating in the radially-extending detent  105  formed in sleeve  15 , whereby to releasably lock screw  20  to sleeve  15 , as will hereinafter be discussed in further detail. Opening  120  has a non-circular cross-section (e.g., hexagonal), in order that screw  20  can be rotatably driven by an appropriate driver. Preferably screw  20  is sized so that when it is seated within sleeve  15 , the distal end of the screw projects out of the distal end of the sleeve (see  FIG. 1 ). 
     Sleeve  15  and screw  20  can be used to secure a plate to bone. By way of example but not limitation, sleeve  15  and screw  20  can be used to secure plate  10  to a fractured bone so as to stabilize that bone. In this circumstance, plate  10  extends across the fracture line, with each end of the plate being secured to the bone using a sleeve/screw construction. Significantly, each sleeve/screw construction can be oriented at a different angle relative to plate  10 , so as to better distribute load and/or apply a compressive force. 
     More particularly, and looking now at  FIG. 15 , there is shown a bone B having a fracture F. In order to stabilize fracture F, a plate may be secured to the bone on either side of fracture F. To this end, and looking now at  FIG. 16 , plate  10  is positioned against bone B, and then a bone hole H is drilled into the bone beneath each of the openings  35  which are to receive a sleeve/screw construction. This is done by passing a drill through opening  35  in plate  10  and into the bone. Due to the construction of plate  10  and sleeve  15 , bone hole H can be set at any one of a number of different orientations relative to plate  10 , e.g., bone hole H can extend at an acute angle relative to the plane of plate  10  (see, for example,  FIG. 16 ) or bone hole H can extend at a right angle to the plane of plate  10  (not shown). This construction allows the surgeon to select the most desirable orientation for the bone hole, taking into account factors such as bone quality, force distribution, angle of approach, etc. 
     Once bone holes H have been drilled in bone B, sleeves  15  are advanced through plate openings  35  and into bone holes H ( FIGS. 17 and 18 ). This is done by turning sleeve  15  with an appropriate rotational driver. Sleeve  15  is advanced until shank  60  is disposed in bone B and head  65  is seated in plate counterbore  45 . At this point, sleeve  15  will serve to provide some degree of attachment of plate  10  to bone B, by virtue of the engagement of screw threads  75  with bone B and head  65  with counterbore  45 . 
     As noted above, sleeve  15  is preferably sized so that, when sleeve  15  is deployed in a plate  10  and into bone B ( FIG. 17 ), the distal end of shank  60  extends beyond the cortical bone/cancellous bone interface I, so as to provide enhanced stabilization, as will hereinafter be discussed in further detail. 
     Next, screw  20  is advanced down opening  70  in sleeve  15  ( FIGS. 19 and 20 ). As this occurs, sleeve  15  can be held against rotation using sleeve slots  85 . The advancing screw  20  causes sleeve  15  to be radially expanded, so that the sleeve is simultaneously secured to both bone B and to plate  10 . More particularly, the distal end of shank  60  of sleeve  15  is expanded so that the sleeve engages the cancellous portion of bone B, the proximal end of shank  60  of sleeve  15  engages the cortical portion of bone B, and head  65  of sleeve  15  engages plate  10 . Significantly, sleeve  15  is sized so that the distal end of the sleeve mushrooms open beyond the cancellous bone/cortical bone interface I, making a tight securement between plate  10  and bone B. 
     Screw  20  is advanced until locking finger  130  seats in sleeve detent  105 , thereby releasably locking the screw in position relative to the sleeve. Engagement of locking finger  130  in sleeve detent  105  also serves as an indicator, with tactile feedback, that the screw has been advanced to the proper extent (and not overtightened) relative to the sleeve. 
     Significantly, inasmuch as sleeve  15  opens laterally and presents a substantially larger profile than screw  20  alone, the disposition of the combination of sleeve and screw in the plate and the bone provides much better contact with the plate and the bone, thereby enhancing securement and shear resistance. This is particularly true since the distal end of sleeve  15  opens just beyond the cortical bone/cancellous bone interface I, so that plate  10  is secured to bone B under tension. In addition, since screw  20  is being advanced into sleeve  15  and not directly into the bone, there is little likelihood that the screw will lose its purchase and become a spinner. Furthermore, in the unlikely event that the screw should become a spinner, the situation can be easily rectified by removing screw  20  from sleeve  15  and removing sleeve  15  from the bone and plate  10 . This leaves the host bone in condition for the procedure to be repeated with a new sleeve and/or a new screw, reusing the same bone hole. 
     Additional Constructions 
     It is possible to modify the constructions described above without departing from the scope of the present invention. 
     By way of example but not limitation, plate  10  might be formed with a non-rectangular and/or curved configuration, so as to seat more securely against a curved bone surface. See, for example,  FIGS. 21-25 , which show one such construction for plate  10 . 
     By way of further example but not limitation, sleeve  15  might be formed with ribs (or other lateral projections)  75  instead of a screw thread  75 . See, for example,  FIGS. 26-28 , which show a sleeve  15  formed with ribs  75 . In this case, sleeve  15  might be set with a mallet driver, etc., rather than with a rotational driver. Where sleeve  15  is formed with ribs  75 , ribs  75  may be given a profile to facilitate insertion and impede withdrawal from the bone, e.g., sloped leading edges  135  and sharp rims  140 . 
     Also by way of example but not limitation, screw  20  may be sized to terminate within sleeve  15  rather than extend out the end of sleeve  15 . Furthermore, screw thread  125  of screw  20  might be replaced by ribs (or other lateral projections)  125  for engaging the interior side wall of sleeve  15 . See, for example,  FIG. 29 , which shows such a ribbed construction. In this case, or in other cases, the interior side wall of sleeve  15  might not be threaded. Additionally, screw  20  can be cannulated, so as to facilitate delivery over a guidewire. 
     Furthermore, sleeve  15  might be formed without a counterbore, and screw  20  might be formed without an enlarged head, in which case the screw would essentially constitute a threaded pin to be seated within a sleeve bore. 
     Additionally, the positions of detent  105  and finger  130  may be reversed, i.e., finger  130  may be formed on sleeve  15  and detent  105  may be formed on screw  20 . Additionally, more than one detent and/or finger may be provided, e.g., the apparatus may comprise one finger and multiple detents. 
     Also, screw  20  and sleeve  15  may be pre-assembled (either at the time of manufacture or in the operating room) so as to constitute a single unit. 
     It should also be appreciated that the present invention may be used to secure a rod (or the like) to bone. By way of example but not limitation, the rod could be a spinal rod (or other surgical rod) used to stabilize a plurality of vertebral bodies relative to one another. In this case, a portion of the rod might be modified so as to be analogous to plate  10  (e.g., so as to provide one or more openings  35  through the rod for receiving a sleeve  15  and screw  20 ). See  FIG. 30 , where a rod  141  is provided with one or more openings  35  therethrough. Where the rod has a relatively narrow diameter, and looking now at  FIG. 31 , a portion of rod  141  might be flattened and/or laterally expanded so as to provide an enlarged surface area  142  for receiving openings  35  to receive sleeve  15 . However, where the rod has a relatively large diameter, openings  35  may be formed in the rod without requiring any flattening and/or lateral expansion of the rod. 
     Alternatively, an adapter might be provided to secure the rod to bone. In this case, and looking now at  FIG. 32 , plate  10  could function as a rod mount, preferably with a groove  143  on the underside of the plate to capture the rod to the bone. In this case, it may be necessary to position openings  35  in plate  10  so that a sleeve  15  passing through openings  35  will pass alongside a rod captured in the groove. See  FIG. 32 . 
     Additionally, the novel sleeve/screw construction can be used to secure a tulip-shaped mount to the bone, with the tulip-shaped mount being used to secure a rod to the bone. More particularly, and looking now at  FIG. 33 , a tulip-shaped mount  144  is shown, wherein the tulip-shaped mount has an opening  35  for securing the tulip-shaped mount to bone and a slot  145  for receiving a rod. 
     In use, tulip-shaped mount  144  is positioned alongside bone. A hole is drilled in the bone via opening  35  formed in tulip-shaped mount  144 . Sleeve  15  is advanced through opening  35  ( FIG. 34 ) and into the hole formed in the bone. Next, screw  20  is advanced through sleeve  15 , causing sleeve  15  to be radially expanded, so that the sleeve is simultaneously secured to both the bone and to tulip-shaped mount  144  (see  FIG. 35 ). With tulip-shaped mount  144  secured to the bone, a rod may be positioned in the slot  145  of tulip-shaped mount  144 , whereby to stabilize the bone(s). If desired, tulip-shaped mount  144  may be provided with a threaded cap (not shown) which can be positioned superior to the rod using threads  150 , so as to securely hold the rod in place within slot  145  of tulip-shaped mount  144 . 
     Looking next at  FIGS. 36 and 37 , it should also be appreciated that sleeve  15  can be formed integral with tulip-shaped mount  144 . 
     Method and Apparatus for Stabilizing Bone 
     In many situations it may be necessary, or desirable, to stabilize bone. By way of example but not limitation, where a bone is fractured, it may be desirable to stabilize the bone with a bone plate which extends across the fracture line. By way of further example but not limitation, where two separate bones need to be secured together (e.g., in the case of a spinal fusion), it may be desirable to secure the bones to one another with a bone plate which extends from one bone to the other. In some cases, bridging or spacer material (e.g., allograft, autograft, biologic, etc.) may be placed as a graft between the two bones to stabilize and/or to enhance the fusion process of the two bones being secured together. Furthermore, in some situations (e.g., multi-level spinal surgery), it may be desirable to secure together more than two bones (e.g., in 3-level spinal surgery, it may be desirable to secure together three separate vertebral bodies). Again, bridging or spacer material may be placed as a graft between the individual bones. 
     In all of the foregoing situations, as well as in many other situation&#39;s which are well known to those skilled in the art, a plate or plates generally need to be secured to bone. Such securement is most commonly effected by using a surgical screw which passes through a hole in the plate and into the bone. 
     When using a surgical screw to secure a plate to bone, the plate is first aligned with the bone. Then a hole is drilled into the bone, by passing a drill through the pre-existing hole in the plate and into the bone. Next, the hole may be tapped. Then the surgical screw is screwed through the plate and into the hole in the bone. 
     Many different bone plates have been developed. In general, the configuration of these bone plates depends on their use, e.g., a fracture fixation plate may have one configuration, a spinal fusion plate may have another configuration, etc. Typically, the plate configuration seeks to balance anatomical configurations, anatomical loads, etc. 
     Over the past decade or so, anterior cervical fusion (ACF) has gained wide spread acceptance in the spinal community. In general, this procedure involves fusing together two (1-level) or more (multi-level) vertebral bodies. Anterior cervical plates (ACPs) are commonly used to hold the vertebral bodies in position while bone fusion occurs. 
     Current ACPs all suffer from one or more disadvantages, including configurations which do not adequately accommodate anatomical limitations, designs which do not adequately stabilize anatomical loads, etc. Furthermore, current ACPs are not designed to accommodate subsequent surgeries where additional levels of fixation must be added. By way of example, current ACPs are not designed to facilitate converting a 1-level fixation to a 2-level fixation. 
     The present invention is intended to provide a new and improved ACP which improves upon the limitations of the prior art, including providing (i) improved anatomical accommodation, (ii) improved load stabilization, (iii) optional future level extensions, etc. 
     The present invention is intended to address the foregoing deficiencies of the prior art by providing a new and improved method and apparatus for stabilizing bone in general, and vertebral bodies in particular. 
     Among other things, the present invention provides a new and improved ACP system for stabilizing two or more cervical bodies. 
     In one preferred form of the present invention, the new ACP system comprises a plate which is to be attached to two adjacent cervical bodies, and attachment apparatus for attaching the ACP to the two cervical bodies. Preferably, the attachment apparatus comprise a screw and, in one preferred form of the invention, the attachment apparatus comprise a sleeve and screw combination, where the sleeve acts as an interface between (i) the bone and the screw, and (ii) the ACP and the screw, with the sleeve enhancing fixation. Among other things, the ACP is specifically configured to provide the option of adding future level extensions. 
     Looking now at  FIGS. 38-46 , there is shown a new and improved ACP system  500  for stabilizing two or more cervical bodies relative to one another. ACP system  500  generally comprises a primary ACP  600  for effecting a 1-level stabilization, and may further comprise one or more supplemental ACPs  700  for effecting subsequent 1-level stabilizations. Thus, for example, where a 1-level stabilization is to be initially established, and a further 1-level stabilization is to be thereafter established, ACP system  500  may comprise a primary ACP  600  and a secondary ACP  700 , whereby to collectively establish the desired 2-level stabilization. 
     Looking now at  FIG. 39 , primary ACP  600  generally comprises a first, generally toroidal body  605 , a second generally toroidal body  610 , and a bridge  615  connecting first generally toroidal body  605  to second generally toroidal body  610 . First toroidal body  605  and second toroidal body  610  each include (i) at least one opening  620  for receiving a pin  625  for initially tacking primary ACP  600  to the cervical bodies, and (ii) at least one opening  630  for receiving attachment apparatus  635  for thereafter securing primary ACP  600  to the cervical bodies. 
     Attachment apparatus  635  may comprise a spinal screw. More preferably, however, attachment apparatus  635  comprise a sleeve and screw combination of the sort discussed above (i.e., sleeve  15  and screw  20 ) and/or as disclosed in one or more of: (i) pending prior U.S. patent application Ser. No. 10/246,304, filed Sep. 18, 2002 by Barry T. Bickley for FIXATION AUGMENTATION DEVICE AND RELATED TECHNIQUES; (ii) pending prior U.S. patent application Ser. No. 10/554,379, filed Oct. 25, 2005 by Barry T. Bickley et al. for FIXATION AUGMENTATION DEVICE AND RELATED TECHNIQUES; and/or (iii) pending prior U.S. patent application Ser. No. 12/148,845, filed Apr. 23, 2008 by Barry T. Bickley et al. for METHOD AND APPARATUS FOR SECURING AN OBJECT TO BONE. These three patent applications are hereby incorporated herein by reference. 
     Preferably, primary ACP  600  includes recesses  640  ( FIG. 53 ) formed in the sidewalls  645  which define openings  630 . Recesses  640  help to releasably secure attachment apparatus  635  within openings  630 , i.e., by receiving fingers  650  ( FIG. 40 ) formed on the proximal end of attachment apparatus  635 . 
     In order to facilitate the use of primary ACP  600  in conjunction with a supplemental ACP  700 :
         (i) the outer sidewall  651  forming the periphery of second toroidal body  610  is preferably formed with a taper ( FIG. 47 ) in order to mate with a corresponding opening in supplemental ACP  700 , as will hereinafter be discussed in further detail below;   (ii) primary ACP  600  preferably includes a plurality of teeth  655  extending along outer sidewall  651  of second toroidal body  610 , in order to selectively lock primary ACP  600  to a supplemental ACP, as will hereinafter be discussed in further detail below;   (iii) primary ACP  600  is preferably cut back on its lateral edges, adjacent to where second toroidal body  610  meets bridge  615 , i.e., at  660  ( FIG. 41 ), in order to allow primary ACP  600  and a supplemental ACP  700  to assume a wide range of different positions, as will hereinafter be discussed in further detail below;   (iv) primary ACP  600  is preferably cut back on its proximal face, adjacent to where second toroidal body  610  meets bridge  615 , i.e., at  665 , in order to mate with a corresponding portion of a supplemental ACP  700 , as will hereinafter be discussed in further detail below; and   (v) primary ACP  600  includes an opening  670  formed in its proximal face, to facilitate locking primary ACP  600  and a supplemental ACP  700 , as will hereinafter be discussed in further detail.       

     Looking now at  FIG. 40 , supplemental ACP  700  generally comprises a first, generally toroidal body  705 , a second generally toroidal body  710 , and a bridge  715  connecting first generally toroidal body  705  to second generally toroidal body  710 . Second toroidal body  710  includes (i) at least one opening  720  for receiving a pin (not shown) for initially tacking supplemental ACP  700  to a cervical body, and (ii) at least one opening  730  for receiving attachment apparatus  635  for thereafter securing supplemental ACP  700  to a cervical body. 
     Again, attachment apparatus  635  may comprise a spinal screw. More preferably, however, attachment apparatus  635  comprise a sleeve and screw combination of the sort discussed above (i.e., sleeve  15  and screw  20 ) and/or as disclosed in one or more of: (i) pending prior U.S. patent application Ser. No. 10/246,304; (ii) pending prior U.S. patent application Ser. No. 10/554,379; and/or (iii) pending prior U.S. patent application Ser. No. 12/148,845. 
     Preferably, supplemental ACP  700  includes recesses  740  formed in the sidewalls  745  which define opening  730 . Recesses  740  help to releasably secure attachment apparatus  635  within openings  730 , i.e., by receiving fingers  650  formed on the proximal end of attachment apparatus  635 . 
     In order to facilitate use of supplemental ACP  700  with primary ACP  600 :
         (i) supplemental ACP  700  preferably includes a large opening  775  formed in its first toroidal body  705 , and the sidewall  776  defining opening  775  is preferably formed with a taper ( FIG. 47 ), in order to mate with the correspondingly-tapered second toroidal body  610  of primary ACP  600 , as will hereinafter be discussed in further detail below;   (ii) supplemental ACP  700  preferably includes a plurality of teeth  765  lining at least a portion of opening  775 , in order to selectively lock primary ACP  600  to a supplemental ACP, as will hereinafter be discussed in further detail below;   (iii) supplemental ACP  700  preferably has its first toroidal body  705  cut back adjacent to its free end, i.e., at  760 , in order to allow primary ACP  600  and a supplemental ACP  700  to assume a wide range of different positions, as will hereinafter be discussed in further detail below; and   (iv) supplemental ACP  700  preferably includes strap  780  on its first toroidal body  705 , with strap  780  including a slot  785 , to facilitate locking primary ACP  600  and a supplemental ACP  700 , as will hereinafter be discussed in further detail.       

     In use, primary ACP  600  is initially used to establish 1-level cervical stabilization. This is done by first positioning the two cervical bodies in the desired position, with or without bridging or spacer material (e.g., allograft, autograft, biologic, etc.) being placed as a graft between the two bones to stabilize and/or to enhance the fusion process of the two bones being secured together. Then primary ACP  600  is positioned against the two cervical bodies, with first toroidal body  605  of primary ACP  600  being positioned against one cervical body, and second toroidal body  610  of primary ACP  600  being positioned against a second cervical body. Primary ACP  600  is then pinned to the two bodies, i.e., using pins  625  extending through openings  620 . Alternatively, primary ACP  600  may be pinned to one of the two bodies, the positioning of the two bodies may then be adjusted, and then the primary ACP pinned to the other of the two bodies. Thereafter, primary ACP  600  is secured to the two cervical bodies by passing attachment apparatus  635  through openings  630 . By forming the head of attachment apparatus  635  with a hemispherical profile, and by forming the sidewalls of openings  630  with a corresponding arced profile, attachment apparatus  635  can be set at a range of angles “off the perpendicular” in order to accommodate various surgical considerations, e.g., patient anatomy, load distribution, etc. Furthermore, by forming the head of attachment apparatus  635  with a reduced profile (see  FIGS. 38 and 43 ), attachment apparatus  635  will present a lower profile to the surrounding tissue if and when attachment apparatus  635  are set “off the perpendicular”. 
     In addition to the foregoing, by using attachment apparatus  635  in the form of a sleeve and screw combination of the sort discussed above (i.e., sleeve  15  and screw  20 ) and/or as disclosed in one or more of (i) pending prior U.S. patent application Ser. No. 10/246,304; (ii) pending prior U.S. patent application Ser. No. 10/554,379; and/or (iii) pending prior U.S. patent application Ser. No. 12/148,845, a significant advantage is obtained. More particularly, by using attachment apparatus  635  of this type, the sleeve is effectively interposed between the screw and the ACP. Thus, it is the sleeve which is loaded by the ACP and therefore there is no transfer of motion forces directly onto the screw. As a result, there is a reduced tendency for the screw to back out over time. 
     If and when the 1-level stabilization of primary ACP  600  needs to be extended to a 2-level stabilization, a supplemental ACP  700  is used. More particularly, and looking still at the figures, first toroidal body  705  of supplemental ACP  700  is fit over second toroidal body  610  of primary ACP  600 , with second toroidal body  610  of primary ACP  600  being received in large opening  775  ( FIG. 41 ) of first toroidal body  705  of supplemental ACP  700 . Seating of second toroidal body  610  of primary ACP  600  in large opening  775  of supplemental ACP  700  is facilitated by complementary tapered surfaces  651 ,  776  ( FIG. 47 ). Furthermore, by forming primary ACP  600  with surfaces  651  which taper inwardly as they move away from the bone, and by forming supplemental ACP  700  with surfaces  776  which taper outwardly as they move toward the bone, fitting supplemental ACP  700  over primary ACP  600  will help clear away any tissue which may have grown over the primary ACP while it has been implanted (e.g., in a revision situation). As second toroidal body  610  of primary ACP  600  is received in large opening  775  ( FIG. 41 ) of first toroidal body  705  of supplemental ACP  700 , teeth  655  of primary ACP  600  engage with teeth  765  of supplemental ACP  700  so as to fix the two bodies relative to one another, with strap  780  of supplemental ACP  700  overlying bridge  615  of primary ACP  600 . Then a screw (not shown) is passed through slot  785  in bridge  780  ( FIG. 38 ) and into opening  670  in bridge  615  ( FIG. 39 ), whereby to lock primary ACP  600  and supplemental ACP  700  into position relative to one another. Thereafter, supplemental ACP  700  is secured to the third cervical body by passing attachment apparatus  635  through opening  730 . By forming the head of attachment apparatus  635  with a hemispherical profile, and by forming the sidewalls of openings  730  with a corresponding arced profile, attachment apparatus  635  can be set at a range of angles “off the perpendicular” in order to accommodate various surgical considerations, e.g., patient anatomy, load distribution, etc. Furthermore, by forming the head of attachment apparatus  635  with a reduced profile (see  FIGS. 38 and 43 ), attachment apparatus  635  will present a lower profile to the surrounding tissue if and when attachment apparatus  635  are set “off the perpendicular”. 
     In addition to the foregoing; by using attachment apparatus  635  in the form of a sleeve and screw combination of the sort discussed above (i.e., sleeve  15  and screw  20 ) and/or as disclosed in one or more of: (i) pending prior U.S. patent application Ser. No. 10/246,304; (ii) pending prior U.S. patent application Ser. No. 10/554,379; and/or (iii) pending prior U.S. patent application Ser. No. 12/148,845, a significant advantage is obtained. More particularly, by using attachment apparatus  635  of this type, the sleeve is effectively interposed between the screw and the ACP. Thus, it is the sleeve which is loaded by the ACP and therefore there is no transfer of motion forces directly onto the screw. As a result, there is a reduced tendency for the screw to back out over time. 
     Due to the construction of primary ACP  600  and supplemental ACP  700 , the primary ACP and the supplemental ACP can be aligned in a variety of orientations, i.e., on-axis ( FIG. 38 ) or off-axis ( FIGS. 48 and 49 ) before being secured. In essence, supplemental ACP  700  can be “dialed around” primary ACP  600 , according to the particular anatomical situation encountered by the surgeon. This can be particularly helpful in revision cases, since the surgeon does not need to remove a mis-aligned primary ACP  600  in order to get proper alignment of a supplemental ACP  700 . 
     If further levels of stabilization are required, additional supplemental ACPs  700  can be added in a serial fashion. To this end, second toroidal body  710  of supplemental ACP  700  includes teeth  790  for mating with teeth  765  of an immediately-proceeding supplemental ACP  700 . Again, each incremental supplemental ACP  700  may be set on-axis or off-axis from its immediately-preceding ACP, as dictated by the existing position of the immediately-preceding ACP and by the patient anatomy being encountered. 
     Among other things, it should be appreciated that when attachment apparatus  635  include receiving fingers  650  ( FIG. 40 ), and when primary ACP  600  and supplemental ACP  700  include recesses  640 ,  740 , attachment apparatus  635  are able to pivot relative to primary ACP  600  and supplemental ACP  700 . This construction permits primary ACP  600  and/or supplemental ACP  700  to pivot relative to attachment apparatus  635  (and hence pivot relative to the cervical bodies receiving the distal ends of attachment apparatus  635 ), without permitting longitudinal and/or lateral translation of primary ACP  600  and/or supplemental ACP  700  relative to attachment apparatus  635  (and hence the cervical bodies receiving the distal ends of attachment apparatus  635 ). See  FIGS. 50 and 51 . 
     Alternative Constructions 
     If desired, primary ACP  600  may have more than one opening  630  per level, and/or supplemental ACP  700  may have more than one opening  730  per level. Furthermore, primary ACP  600  may extend for more than two levels, and/or supplemental ACP  700  may extend for more than two levels. 
     Furthermore, openings  630  and/or openings  730  may have a round or oval shape. The oval shape is generally preferred, since it provides an anti-rotation feature when attachment apparatus  635  comprise a sleeve and screw combination. Furthermore, the oval shape provides some opportunity for the attachment apparatus  635  to slide within the opening. 
     In addition to the foregoing, recesses  640  and  740  can comprise a hemisphere or an elongated slot. Where recesses  640  and  740  comprise an elongated slot, the slot can itself provide several seats to accommodate a range of engagements. By way of example but not limitation, the slot can comprise a plurality of detents spaced along the length of the slot for selectively seating fingers  650 , whereby to permit adjustable engagement of attachment apparatus  635  to primary ACP  600  and supplemental ACP  700 . 
     By forming openings  630 ,  730  with an oval shape, and by forming recesses  640 ,  740  in a slot configuration with several seats, dynamic fixation can be effected. More particularly, the foregoing construction permits primary ACP  600  and/or supplemental ACP  700  to translate longitudinally relative to attachment apparatus  635  (and hence translate longitudinally relative to the cervical bodies receiving the distal ends of attachment apparatus  635 ), without permitting lateral translation of primary ACP  600  and/or supplemental ACP  700  relative to attachment apparatus  635  (and hence the cervical bodies receiving the distal ends of attachment apparatus  635 ). See  FIG. 52 . 
     It should also be appreciated that teeth  655  of primary ACP  600 , teeth  765  of supplemental ACP  700 , and teeth  790  of supplemental ACP  700  may all be replaced with facet structures. These facet structures may be configured so as to provide fast and simple alignment and assembly of adjoining ACPs. 
     Protective Collars 
     Primary ACP  600  and/or supplemental ACP  700  may be provided with a protective collar so as to minimize tissue ingrowth about second generally toroidal body  610  and/or second generally toroidal body  710 , respectively. See, for example,  FIG. 53 , which shows a protective collar  800  set about second generally toroidal body  610 , and  FIG. 54 , which shows a protective collar  805  set about second generally toroidal body  710 . 
     Protective collars  800  and/or  805  are preferably pre-applied to primary ACP  600  and/or supplemental ACP  700 , respectively, prior to deployment of the ACP into the body, although the protective collars may also be applied after an ACP has been deployed in the body. 
     If primary ACP  600  and/or supplemental ACP  700  is equipped with a protective collar, and if an additional level of fixation is to be added (i.e., if a supplemental ACP  700  is to be added to the ACP structure(s) already in place), that protective collar is removed before the supplemental ACP is deployed, so that the supplemental ACP can be fixed to the ACP structure(s) already in place. 
     Materials 
     The various components can be formed out of any material or materials consistent with the present invention. Thus, for example, some or all of the components may be formed out of implantable metals (e.g., surgical grade stainless steel, titanium, Nitinol, etc.), implantable plastics, implantable absorbables, etc. 
     Modifications 
     It will be understood that many changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art without departing from the principles and scope of the present invention.