Abstract:
Methods and apparatus for compressing and/or distracting bones are described herein. In one such method, a tap marker is engaged with a bone and a compressor/distractor device. The tap marker can be removed after moving the bone and a bone screw can be inserted into the space previously occupied by the tap marker. A rod or other fixation element can then be attached to the bone screw.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62/276,456 filed Jan. 8, 2016, the disclosure of which is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a method of positioning bone. Specifically, a method of positioning vertebrae using a tap marker is described herein. 
         [0003]    Current methods of distracting or compressing vertebrae include screw based decompression. One advantage of using screws during decompression is they provide a landmark to track the location of bone during the procedure. The screws used for decompression typically include polyaxial screws, which include a bone screw and head (tulip) that can be moved with respect to the screw. These polyaxial screws may be pre-assembled or may be modular in design. Polyaxial bone screws are widely utilized as they allow for greater flexibility is use and take less space in the surgical site. 
         [0004]    However, there are also disadvantages associated with using bone screws for distraction or compression. For instance, forces are put on the screws during distraction which can possibly cause damage to the screw/tulip interface. Elongation of bone from over-distraction (windshield wiper effect) when using screws can also occur, which may require the screw to be replaced with a larger screw. Bone screws also frequently disengage from the distractor under a compressive load. This forces the surgeon to skip the distraction step or use an additional instrument such as a lamina spreader. Therefore, a need exists for an improved method of positioning bone. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    One aspect of the disclosure includes a method for moving a vertebral body which desirably includes inserting a first member into a first vertebral body at a first location, moving the first member to move the first vertebral body, removing the first member from the first vertebral body, and positioning a first anchor into the first vertebral body at the first location. The method may include creating an opening in the vertebra prior to the inserting step and the inserting step may include inserting the first member in the opening. 
         [0006]    The first member can be a tap and the inserting step may include creating a threaded opening at the first location. The first anchor may be a bone screw or a pedicle screw with a head adapted to receive a rod and the method can further include coupling a rod to the screw head. The first location may be at a pedicle of the first vertebral body. The method may further comprise inserting a second member into a second vertebral body and moving the second vertebral body with respect to the first vertebral body. The moving step can include engaging an instrument with the first and second members to permit at least one of compression and distraction of the first and second vertebral bodies. The creating an opening step can include drilling a hole in the vertebral body. The method can further include inserting an implant between the first and second vertebral bodies. 
         [0007]    Another aspect of the disclosure describes a method of moving vertebral bodies comprising inserting a first tap in a first vertebral body to create a first threaded opening in the first vertebral body; inserting a second tap in a second vertebral body to create a second threaded opening in the second vertebral body; coupling an instrument to the taps while the taps are within the first and second threaded openings; moving the first and second vertebral bodies with the instrument; removing the first and second taps; inserting a first bone screw in the first threaded opening; and inserting a second bone screw in the second threaded opening. 
         [0008]    The first tap may have a tap head and the first bone screw can have a screw head wherein the tap head is smaller than the screw head. The moving step may comprise at least one of compression and distraction of the vertebral bodies. The first member can include a head separated from a threaded section by an extension and the moving step can include engaging the extension with an instrument. 
         [0009]    Another aspect of the disclosure describes a method of compressing or distracting bone which includes inserting first and second taps into first and second bones to create first and second threaded openings; coupling an instrument to the first and second taps; moving the first and second bones with the instrument while the taps are in the first and second threaded openings; removing the taps; inserting first and second bone screws into the first and second threaded openings; and coupling a rod to the first and second bone screws. The first and second bones can be first and second vertebral bodies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  illustrates a tap marker in accordance with one embodiment of the present invention. 
           [0011]      FIG. 2  illustrates an insertion instrument coupled to the tap marker of  FIG. 1 . 
           [0012]      FIG. 3A  is a cross-sectional view detailing the coupling of the insertion instrument and tap marker of  FIG. 2 . 
           [0013]      FIG. 3B  is a cross-sectional view focusing on the coupling of the insertion instrument and tap marker. 
           [0014]      FIGS. 4A and 4B  illustrate tap marker adapters in accordance with embodiments of the present invention. 
           [0015]      FIG. 5  illustrates a distraction instrument in accordance with one embodiment of the present invention. 
           [0016]      FIG. 6  illustrates the distraction instrument of  FIG. 5  coupled to two tap marker adapters of  FIG. 4  engaged with two tap markers of  FIG. 1 . 
           [0017]      FIG. 7  illustrates the distraction instrument of  FIG. 5  engaged with two distraction posts in accordance with one embodiment of the present invention. 
           [0018]      FIG. 8  illustrates the distraction instrument of  FIG. 5  engaged with two lamina hooks in accordance with one embodiment of the present invention. 
           [0019]      FIG. 9  illustrates the distraction instrument of  FIG. 5  engaged with two spinous process hooks in accordance with one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  illustrates one embodiment of a tap marker  10  in accordance with the present disclosure. Tap marker  10  shown in  FIG. 1  includes a body  12  having a helical thread  14 . Tap marker  10  includes a cutting flute  16  extending from a tip  18  along body  12 . Cutting flute  16  allows tap marker  10  to self-drill into the bone. Of course, the tap marker could also be formed without a flute and inserted into a pre-drilled hole. Although shown as a solid structure, it is contemplated to form tap marker  10  as a cannulated component, thus allowing for its placement over a K-wire or the like. 
         [0021]    A neck  22  is formed on body  12  adjacent thread  14 . As will be explained in greater detail below, a distraction instrument or other component can be coupled to an extension  28  or another portion (e.g., neck  22 ) to move tap marker  10 . A radius  24  forms the transition between neck  22  and a collar  20 . Radius  24  reduces stress concentration along the tap marker during insertion or movement of the tap marker. Collar  20  prevents axial translation of the distraction tool during a surgical procedure when the instrument engages the tap marker at neck  22 . The collar also prevents over-insertion of the tap marker into the bone, as well as cooperation with a tap marker adapter (discussed below). Tap marker  10  includes an extension  28  positioned between collar  20  and head  26  that is adapted to engage an insertion instrument. Extension  28  shown has a cross-sectional shape adapted to engage an insertion instrument (e.g. hexagon, square, ovular, octagonal, etc . . . ). Of course, head  26  could also be adapted to engage a driving instrument. For instance, head  26  could exhibit a shape similar to that of extension  28 . In other embodiments, head  26  could be designed with a female engagement member (e.g. Phillips, Torx, socket). 
         [0022]      FIGS. 2-3B  illustrate an insertion instrument  32  coupled to the tap marker  10 . The insertion instrument has an opening  34  at its distal end  36  adapted to receive head  26  and extension  28  of tap marker  10 . The insertion instrument preferably exhibits a shape complimentary to the shape of extension  28 , but of course, could also have any desired engagement feature (e.g. Phillips, Torx, socket) to engage tap marker  10 . Likewise, in concert with the foregoing, opening  34  could be designed to solely receive head  26 , or insertion instrument  32  may include a male engagement member for engaging a female engagement member in head  26 . In the particular arrangement best depicted in  FIG. 3B , opening  34  is designed to receive both head  26  and extension  28  and instrument  32  further includes inner and outer members  35   a  and  35   b  and detent  37 . The operation of these components is such that movement of the inner and outer members with respect to each other results in detent being moved and/or fixed into a position in which head  26  is captured. This allows for marker  10  to be retained by instrument  32 , which allows for easy manipulation of the marker during surgery. The insertion instrument of  FIGS. 2-3  is manually operated but could also be a powered driver (e.g. screw gun). In other embodiments, insertion instrument  32  may be designed as a torque-limiting instrument, a ratchet instrument or the like. To facilitate acceptance of a K-wire extending through tap marker  10 , portions or the entirety of instrument  32  may be cannulated. 
         [0023]      FIG. 4A  illustrates a tap marker adapter  40 . As shown, the adapter includes an aperture  42  and a shaft  44 , which in the embodiment shown are offset with respect to one another. It is contemplated though to have the two elements aligned in different fashions, including coaxially (e.g., shaft  44  would in effect be partially or fully cannulated). Aperture  42  is shown as exhibiting a size designed to accept body  12  of tap marker  10 , while abutting up against collar  20 . Of course, other sizes are contemplated for accepting different portions of tap marker  10 . Shaft  44  is shown as exhibiting a smooth semi-circular outer-surface, but other embodiments may be of any shape and/or may include surface roughening or the like. 
         [0024]    For instance,  FIG. 4B  illustrates another embodiment tap marker adapter  40 ′, which includes a shaft  44 ′ that includes roughened surface  45 ′. Preferably, shafts  44  and  44 ′ are designed to be accepted by portions of the distraction instrument discussed below, where roughened surface  45 ′ may further aid in keeping the adapter coupled with the distraction instrument. 
         [0025]    Although many different distraction instruments may be employed in connection with the present invention,  FIG. 5  depicts one such instrument  50 . As shown, distraction instrument  50  includes two arms  52   a  and  52   b  with barrels  54   a  and  54   b,  respectively, on their distal ends and coupled with a distraction element  56  on their proximal ends. Arms  52   a  and  52   b  are shown as being jointed, which allows manipulation of construct to facilitate use in different surgical settings. However, it is contemplated that the arms may be of a solid construction or articulatable in different areas, such as at the coupling with distraction element  56 . Barrels  54   a  and  54   b  are shown fixed to arms  52   a  and  52   b,  but could also be capable of moving with respect to the arms. The barrels exhibit a semi-circular shape for cooperation with the above-discussed shafts  44 , but, like those latter elements, can be of any shape. The semi-circular design does allow for a rotationally fixed arrangement between the barrels and the shafts which is beneficial in the intended use of the instrument. Distraction element  56  is a rack and pinion design, but of course could be many different known arrangements suitable for distracting or compressing vertebrae. For instance, while the design of distraction instrument  50  is similar to known Caspar distracters, a plier-like design or the like could be employed. Other suitable distraction instruments contemplated for use with the present system are described in U.S. Pat. Nos. 6,090,113 and 8,157,809, the disclosures of which are hereby incorporated by reference herein. 
         [0026]    In use, tap markers  10  are first inserted into vertebral bodies  30 . Prior to the insertion of the markers, the necessary incisions are made to establish the necessary corridors for the procedure. These incisions may be of any size depending upon the type of procedure being conducted or the number of levels of spine being fused. For instance, the present invention can be utilized in more traditional procedures, which require larger incisions or percutaneous MIS procedures, which require smaller incisions. After the incisions are performed the vertebral bodies are prepared for acceptance of tap markers  10 . This may include imagining to determine a proper insertion orientation, pre-drilling to create an initial corridor for the markers and/or inserting a K-wire or the like to aid in the placement of the markers. Use of K-wires, as discussed above, generally requires tap markers  10  to be cannulated. In the case of pre-drilled holes, such may be longer or shorter than body  12  of tap marker  10 . 
         [0027]    Once the vertebral bodies are at least initially prepared, tap markers  10  are inserted at the desired location via insertion instrument  32  (as shown in  FIGS. 2-3B ). The tap markers may also be placed in different orientations, such as for traditional pedicle screw placement or for a mid-line approach. The leading edge of flute  16  bores a hole (or a larger hole in the case where pre-drilled holes are made) in the bone as tap marker  10  is inserted at the desired location, for instance, into a pedicle of a vertebral body. Thus, threads  14  create a threaded hole as tap marker  10  is advanced into the vertebral body. In certain embodiments, body  12  of tap marker  10  is first placed through aperture  42  of tap marker adapter  40 . This results in collar  20  abutting up against adapter  40 , which is adjacent the vertebra  30 . However, a user could elect to stop inserting the tap marker prior to the collar pinning adapter against vertebral body  30 . The particular design of tap marker  10  and adapter  40  is such that shaft  44  can be situated in different orientations upon rotation of the adapter about the marker. Other designs are contemplated where only a single orientation is allowed. 
         [0028]    Once inserted, the tap marker and adapter construct occupies less volume in the surgical space exterior of vertebral body  30  than would be occupied by screws having a tulip head, which reduces interference between the head and the vertebral body or other heads. The construct is also preferably stronger and more fixed than such screws would exhibit. Thus, the clinician has greater freedom to maneuver the vertebral bodies into their desired orientation. Although the bone illustrated is a vertebral body, the system could be used on any bone or, in the case of fractures, bone fragments. 
         [0029]    With multiple tap markers  10  and tap marker adapters  40 ′ in place, barrels  54   a  and  54   b  can be placed over shafts  44 ′. This is shown in  FIG. 6 , albeit without the adapters and markers having been engaged with vertebral bodies. Preferably, barrels  54   a  and  54   b  are designed to freely slide over shafts  44 ′, but other designs are contemplated. For instance, shafts  44  could be designed to positively engage barrels  54   a  and  54   b,  thereby forming a fixed construct. This could be achieved by employing shafts that have a ball detent or other collapsible structure that, after placement in the barrels, expands to create a fixed construct. In any event, this marker, adapter and distraction instrument construct allows a single instrument to be used to compress or distract the vertebral bodies as desired. Although the foregoing discussion is specific to adapter  40 ′, above-discussed adapter  40  could likewise be utilized. As shown, roughened surfaces  45 ′ of adapters  40 ′ aid in creating a firmer connection between barrels  54   a  and  54   b  and shafts  44 ′. 
         [0030]    After the vertebral bodies are moved, the surgeon may perform several different steps depending upon the procedure being performed. For instance, it is envisioned that, at this time, a fusion implant can be inserted between adjacent vertebral bodies. In this regard, any type of such implant may be utilized and many different types of insertions methods may be utilized. Implants of the PLIF, TLIF and lateral types can be inserted in any known fashion, with and without additional bone promoting substances. For instance, implants like those disclosed in U.S. Pat. Nos. 7,156,874; 7,637,950; 7,985,256; and 8,216,317, the disclosures of which are hereby incorporated by reference herein can be utilized. Of course, it should also be appreciated that the implants could be inserted both before and after removal of distraction instrument  50 , as well as after removal of tap markers  10 . 
         [0031]    When so desired, the tap markers are removed from the vertebral bodies  30 . Traditional pedicles screws can then be positioned in the threaded bone holes created by the tap markers. An example of such a pedicle screw is disclosed in U.S. Pat. No. 6,858,030, the disclosure of which is hereby incorporated by reference herein. A rod can then be secured to the screws, as in well-known pedicle screw procedures 
         [0032]    In certain embodiments of the present invention, the tap markers may be longer or shorter than the pedicle screws that are ultimately placed. Likewise, the size of body  12  or the threads thereon can be of any relationship to similar elements on the pedicle screws. For instance, in one embodiment, body  12  may have a core that is smaller than a similar core of the pedicle screw, but its threads can be wider than the threads of the pedicle screw. The threads of the various elements of the present invention may of course be of any shape, size, profile, pitch, angle, orientation, etc . . . . Likewise, it is contemplated to size taps such that they are either longer or shorter than the pedicle screws that are ultimately implanted. 
         [0033]    Multiple tap markers  10 , adapters  40  (and/or adapters  40 ′), K-wires, pedicle screws, distraction instruments and the like may be provided in a kits allowing for an entire surgical procedure to be conducted. These components may be provided in a container or multiple containers for easy transport and/or sterilization. As mentioned above, the present invention allows for the ultimate placement of pedicle screws and rods, and can be performed on any number of levels of the spine. For instance, as little as two vertebral bodies may be fused together utilizing the apparatus and methods of the present invention, but more than two is clearly within the purview of the present invention. While standard pedicle screws and rods are discussed above, it is contemplated to utilize biased angle screws, growing rods and flexible or dynamic rods in connection with the present invention. 
         [0034]    The tools utilized may also vary depending upon the particular approach/methodology employed. For instance, insertion instrument  32  may be designed to only insert tap markers  10 , but could, in some embodiments, also be utilized to insert the pedicle screws ultimately placed. Similarly, the use of adapters  40  and  40 ′ are discussed above. It is envisioned that distractions instruments could be engaged directly with the tap markers themselves. For instance, barrels  54   a  and  54   b  could be sized and shaped to receive extensions  28  of markers  10 . 
         [0035]      FIGS. 7-9  depict other uses for distraction instrument  50 . In  FIG. 7 , barrels  54   a  and  54   b  are shown engaged with distraction posts  60  which are designed to engage an already implanted pedicle screw and form a fixed construct. For instance, as shown, the posts include threading  62  and an engagement surface  64  on their ends that allows them to be threaded into a coupling element of a polyaxial pedicle screw. Upon the threading, surface  64  preferably engages a screw portion of the pedicle screw which results in a temporary prevention of polyaxial movement between the coupling element and screw. In other words, a fixed construct is created. Because posts  60  are sized to be received within barrels  54   a  and  54   b , distraction instrument  50  can be utilized to compress or distraction the vertebral bodies in this situation.  FIG. 8 , on the other hand, depicts lamina hooks  70  engaged with the barrels. These hooks include hook portions  72  that can be utilized to engage the lamina of vertebral bodies. Thus, in this configuration, distraction instrument  50  can be utilized to compress or distract the vertebral bodies without either tap markers  10  or pedicle screws having been implanted. In  FIG. 9 , spinous process hooks  80  engaged with the barrels. These hooks are similar to lamina hooks  70  but are designed to engage the spinous processes to facilitate distraction or compression of the vertebral bodies. 
         [0036]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.