Abstract:
A posterior spinal implant system configured to immobilize and stabilize spinal segments as an adjunct to fusion in the thoracic, lumbar, and/or sacral spine. The implant system includes a pedicle screw, a spinal rod; a connector connecting the pedicle screw to the spinal rod. The connector includes a connector body, a polyaxial screw receiver positioned on the connector body and configured to receive the pedicle screw and permit polyaxial orientation of the connector relative to the pedicle screw, a polyaxial rod receiver positioned in the connector body and configured to receive the spinal rod and permit polyaxial orientation of the spinal rod relative to the connector, and a lock installed in the polyaxial rod receiver. The lock is operable to lock the connector relative the pedicle screw, lock the polyaxial rod receiver relative to the connector, and lock the spinal rod relative to the polyaxial rod receiver.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 62/143,480 filed Apr. 6, 2015, and entitled “Pedicle Screw And Multi-Axial Connector System,” incorporated by reference herein in its entirety. 
     
    
     FIELD 
       [0002]    The present disclosure relates to posterior spinal implant systems. More particularly, the disclosure relates to implant systems having a pedicle screw, a spinal rod, and multi-axial connector between the rod and the screw. The implant systems are positionable to immobilize and stabilize spinal segments as an adjunct to fusion in the thoracic, lumbar, and/or sacral spine. 
       BACKGROUND 
       [0003]    Improvement is desired in the construction and efficiency of posterior spinal implants for immobilizing and stabilizing spine segments. Current devices desire improvement in that it is difficult to make adjustments to the orientation of the components, and then to lock the relative orientations. 
         [0004]    In particular, what is desired is a spinal implant that enables adjustment of the relative orientations of the components, and to quickly and easily lock the relative positions of the components. 
       SUMMARY 
       [0005]    The disclosure advantageously provides posterior spinal implant systems configured to immobilize and stabilize spinal segments as an adjunct to fusion in the thoracic, lumbar, and/or sacral spine. The systems are advantageously operable to permit adjustment of the relative orientations of a spinal rod and a pedicle screw, and to quickly and easily lock the relative positions of the spinal rod and the pedicle screw. 
         [0006]    In one aspect, an implant system according to the disclosure includes a pedicle screw, a spinal rod; a connector connecting the pedicle screw to the spinal rod. The connector includes a connector body, a polyaxial screw receiver positioned in the connector body and configured to receive the pedicle screw and permit polyaxial orientation of the connector relative to the pedicle screw, a polyaxial rod receiver positioned in the connector body and configured to receive the spinal rod and permit polyaxial orientation of the spinal rod relative to the connector, and a lock installed in the polyaxial rod receiver. The lock is operable to lock the connector relative the pedicle screw, lock the polyaxial rod receiver relative to the connector, and lock the spinal rod relative to the polyaxial rod receiver. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Further advantages of the disclosure are apparent by reference to the detailed description when considered in conjunction with the figures, which are not to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein: 
           [0008]      FIGS. 1 and 2  depict a posterior spinal implant system according to the disclosure installed on a spine. 
           [0009]      FIGS. 3 and 4  show the system of  FIGS. 1 and 2 . 
           [0010]      FIG. 5  is an assembled view of components of a posterior spinal implant system of  FIGS. 1 and 2 . 
           [0011]      FIGS. 6 and 7  are exploded views of the components of  FIG. 5 . 
           [0012]      FIGS. 8 and 9  are close up perspective views of a polyaxial rod receiver, and  FIG. 10  is an exploded view of the polyaxial rod receiver of  FIGS. 8 and 9 . 
           [0013]      FIG. 11  is a close up perspective view of a connector, and  FIG. 12  is an exploded view of the connector of  FIG. 11 . 
           [0014]      FIG. 13  is a cross-sectional view of the implant system of  FIG. 5 . 
           [0015]      FIG. 14  is a partially exploded of components of the implant system of  FIG. 5 . 
           [0016]      FIG. 15  is another assembled view of the implant system of  FIG. 5 . 
           [0017]      FIG. 16-23  illustrates relative movements of the components of the implant system of  FIG. 5 . 
           [0018]      FIG. 24  is a cross-sectional view of a pedicle screw used in the implant system of  FIG. 5 . 
           [0019]      FIG. 25  is a perspective view of an alternative embodiment of a pedicle screw for use in implant systems according to the disclosure. 
           [0020]      FIG. 26  is a close-up view of a portion of the pedicle screw of  FIG. 25 . 
           [0021]      FIG. 27  shows an alternate embodiment of a posterior spinal implant system according to the disclosure. 
           [0022]      FIG. 28  is a cross-sectional view of the implant system of  FIG. 27 . 
           [0023]      FIGS. 29-31  show components of the implant system of  FIG. 27 . 
           [0024]      FIG. 32  shows an alternate embodiment of a posterior spinal implant system according to the disclosure. 
           [0025]      FIG. 33  is a cross-sectional view of the implant system of  FIG. 32 . 
           [0026]      FIG. 34  shows a screw component of the implant system of  FIG. 27 . 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    With initial reference to  FIGS. 1-24 , the disclosure relates to a posterior spinal implant system  10 .  FIGS. 1-2  show a pair implants I each utilizing a pair of the implant systems  10  installed on pedicles P of spinal segments S. 
         [0028]    It will be appreciated that a variety of implant configurations may be constructed utilizing the components of the implant systems described herein. The implant systems  10  and the resulting implants I are configured to provide immobilization and stabilization of spinal segments as an adjunct to fusion in the thoracic, lumbar, and/or sacral spine. 
         [0029]    The spinal implant system  10  includes, as major components, a pedicle screw  12 , a polyaxial rod receiver  14 , a connector  16 , and a spinal rod  18 . Two or more of the implant systems  10  may share a single rod  18  as shown. Each of the components is desirably made of a surgical grade metal. 
         [0030]    The pedicle screw  12  is specially configured for use with the implant system  10  and includes a preferably elongated tapered shank  20  having a plurality of threads  22 . The pedicle screw  12  also includes an external drive surface  24  and a cannulated post  26  above the external drive surface  24 . The cannulated post  26  includes a smooth exterior sidewall  28  and an interior drive surface  30  on the interior sidewall of an interior bore  32 . 
         [0031]    The user will have the option to drive/extract the pedicle screw  12  with the interior drive surface  30  in the post  26 , or the external drive surface  24  at the base of the post  26 . A threaded receiver  34  (FIGS,  17  and  24 ) is located at the bottom of the bore  32  of the pedicle screw  12 . The threaded receiver  34  provides an attachment point for both internal and external drivers in order to eliminate screw toggle when either of the drivers is attached. The screw  12  may be of solid construction or cannulated to include a central cannula  36  ( FIG. 24 ). 
         [0032]    The polyaxial rod receiver  14  is specially configured for use with the implant system  10  and includes a tulip housing  40 , a yoke  42 , and an end cap  44 . The housing  40  includes an interior cavity having sidewalls  46   a  and  46   b  and a bottom  48 . Aligned U-shaped slots  50   a  and  50   b  are formed between the sidewalls  46   a  and  46   b  for receiving the rod  18 . A central base  52  extends from an exterior lower portion of the housing  40 . The base  52  has a curved or spherical exterior sidewall  54  terminating at a flat lower end  56 . 
         [0033]    A bore  58  extends through the bottom  48  and the base  52  of the polyaxial rod receiver  14  for passage of the yoke  42 . Slots  60   a  and  60   b  are provided on the interior of the sidewalls  46   a  and  46   b  for receiving the yoke  42 , and female threads  62   a  and  62   b  are located on the interior of the sidewalls  46   a  and  46   b  for receiving male threads of a set screw  64  installable on the polyaxial rod receiver  14 . The set screw  64  is utilized to lock the spinal rod  18  to the polyaxial rod receiver  14 , however, it will be understood that other locking structures may be utilized if desired, to provide a lock structure to lock the spinal rod  18 . For example, the polyaxial rod receiver  14  may be configured to utilize other lock structures such as a locking wedge, a cam, caps, luer locks, and other structures configured to mechanically lock the spinal rod  18  in place. 
         [0034]    The yoke  42  is a Y-shaped member having an upright  70  and a depending leg  72 . The distal end of the leg  72  includes an undercut  74  and threads  76 . The end cap  44  includes an external curved or spherical sidewall  80  and internally threaded bore  82 . The bore  82  aligns with the bore  58  and threads onto the threads  76  of the leg  72  of the yoke  42 , with the cap  44  seating to the undercut  74 . When the end cap  44  is installed on the yoke  42 , the spherical sidewall  54  of the base  52  of the yoke  42  and the spherical sidewall  80  of the end cap  44  combine to provide a sphere  84  for seating in the connector  16  ( FIG. 13 ). 
         [0035]    The connector  16  is specially configured for use with the implant system  10  and includes an elongate body  90 , a wedge  92  slidingly located in the body  90 , a piston  94 , and a polyaxial screw receiver  96 . 
         [0036]    The body  90  of the connector  16  is configured as a generally rectangular ring and includes a rear wedge section  98  for slidingly receiving the wedge  92 . The wedge section  98  includes angled slots  100  on the sidewalls thereof for receiving angled projections  102  of the wedge  92 . Downward pressure on the wedge  92  will tend to urge the wedge  92  downward and forward corresponding to the travel of the projections  102  in the angled slots  100 . The upper inside of the wedge section  98  is cylindrical to match the spherical portion of the polyaxial rod receiver 
         [0037]    The upper inside and terminal end of the wedge section  98  is curved/spherical to match the curved/spherical portion of the polyaxial rod receiver  14 . The wedge section  92  desirably includes a curved floor  104  for engaging the sphere  84  of the polyaxial rod receiver  14  to facilitate polyaxial range of motion for the sphere  84  of the polyaxial rod receiver  14  relative to the connector  16 , including translation or lateral movement of the sphere  84  relative to the connector. 
         [0038]    The body  90  includes a forward section  106  forward of the wedge section  98  and configured for receiving the piston  94  and the polyaxial screw receiver  96 . The interior sidewalls of the forward section  106  include cut-outs  108  therein to provide a space for inserting the piston  94  and the polyaxial screw receiver  96 . 
         [0039]    The piston  94  includes a rectangular boss  110  on either side thereof. The bosses  110  align with mating slots  112  on the interior of the body  90  to prevent axial rotation of the piston and provide a track for its lateral movement against the polyaxial screw receiver  96 , when the connector  16  is actuated. The piston  94  includes a curved front surface  114  for engaging the polyaxial screw receiver  96 . In this regard, the polyaxial screw receiver  96  has a central bore for receiving the pedicle screw  12  and a spherical outer diameter to provide polyaxial screw articulation relative to the connector body  90 . 
         [0040]    The spinal rod  18  may be provided as by a conventional rod of the type used in conventional posterior spinal implants, and is characterized as a cylindrical solid rod with rounded ends. It will be appreciated that various rod configurations may be utilized. 
         [0041]    To install the implant  10  to provide the implant I, the screws  12  are placed in the pedicles P of adjacent ones of the spinal segments S, based on the number of levels or spinal segments to be fused. The connector  16  is placed over the post  26  of each of the screws  12  and is oriented so as to facilitate placement of a spinal rod  18  along the length of the spine, as close to midline of the spine as desired. 
         [0042]    The spinal rod  18  is top-loaded, or placed into the tulip housing  40  and the set screw  64  is threaded into the tulip housing  40 . The bottom of set screw  64  contacts the rod  18 , causing it to press against the yoke  42 . The yoke  42  translates inside the tulip housing  40 , causing the tulip base  52 , to separate from the bottom of the tulip body. A locking force is therefore transmitted through the aforementioned components onto the piston  94 . The piston  94  then translates towards the polyaxial screw receiver  96 . The load causes the polyaxial screw receiver  96  to collapse around the screw post  26  until locking of all components is achieved. Accordingly, rod and tulip angulation/orientation are locked relative to the body  90  of the connector  16 , and the connector/tulip/rod sub-assembly is locked relative to the screw post  26 , all in a single step by tightening of the set screw  64 . 
         [0043]    Orientation of the connectors  16  and the pedicle screws  12  can be adjusted with additional instrumentation to restore proper height and/or orientation of the spinal segments S in order to facilitate proper alignment and fusion of the spine. 
         [0044]    As depicted in  FIGS. 16-23 , the connectors  16  can be adjusted to and locked in a plurality of orientations and configurations in order to accommodate each patient&#39;s spinal anatomy. For example, as represented in  FIG. 16 , the system  10  enables vertical adjustment of the connector  16  on the post  26  of the screw  12 . 
         [0045]    As represented in  FIG. 17 , the connector  16  can rotate clockwise or counter clockwise about the post  26  of the screw  12 . 
         [0046]    As represented in FIG,  18 , the connector  16  can move polyaxially about the post  26  of the screw  12 . 
         [0047]    As represented in  FIG. 19 , the tulip housing  40  can angulate relative to the connector  16  in the medial and lateral directions. 
         [0048]    As represented in  FIG. 20 , the tulip housing  40  can gulate relative to the connector  16  in the cephalad and caudal directions. 
         [0049]    As represented in  FIG. 21 , the tulip housing  40  can rotate about its axis. 
         [0050]    As represented in  FIGS. 22 and 23 , the tulip housing  40  can slide or translate within the connector  16 . 
         [0051]      FIGS. 25 and 26  show an alternate embodiment of a pedicle screw  12 ′ for use in implant systems according to the disclosure. The screw  12 ′ is identical to the screw  12 , except it includes a ledge  120  on the post  26 . The ledge  120  provides a stop for the connector  16  during installation. This placement of the connector  16  abutting the ledge  120  maximizes the allowable angulation of the connector  16  relative to the post  26  of the screw  12 ′. 
         [0052]      FIGS. 27-31  show an alternate embodiment of a posterior spinal implant system  200  according to the disclosure. The implant system  200  includes a pedicle screw  202 , a polyaxial rod receiver  204 , a connector  206 , and a spinal rod  208 . The pedicle screw  202  corresponds to the pedicle screw  12 ′. The receiver  204  corresponds to the polyaxial rod receiver  14 . The spinal rod  208  corresponds to the spinal rod  18 . The connector  206  includes an elongate body  210 , and an elongated piston  212 , and a polyaxial screw receiver  214  having a set screw  216 . The receiver  214  also includes a yoke  218 , corresponding to the yoke  42 . The implant system  200  is installed and locked in a single step, as in the manner described in connection with the implant system  10 . 
         [0053]    The implant system  200  is similar to the implant system  10 , except it does not include a component corresponding to the wedge  92  component of the system  10 , and the component corresponding to the piston component of the system  10  has been lengthened to fill the space of the removed wedge  92 . The wedge  92  as described in connection with the system  10  provided translational movement of the polyaxial rod receiving member  14 . Thus, removal of the wedge  92  as described in connection with the system  200  results in a loss of the translational movement, such as shown in  FIGS. 22 and 23  for the system  10 . Thus, the system  200  is configured for applications not requiring the described translational movement. The other adjustments and movements as described previously for the system  10  and shown in  FIGS. 16-21  will be understood to be applicable to the system  200 . 
         [0054]      FIG. 32-34  show another alternate embodiment of a posterior spinal implant system  250  according to the disclosure. The implant system  250  is identical to the implant system  200 , except the set screw  216  is replaced with a two-stage set screw  252 . Thus, it will be understood that the implant system  250  includes the pedicle screw  202 , the polyaxial rod receiver  204 , the connector  206 , and the spinal rod  208 . 
         [0055]    The two-stage set screw  252  includes a first stage set screw  254  having an upper hex portion  254   a  and a lower set screw section  254   b,  and a second stage set screw  256 . The first stage set screw  254  includes a central through-bore  260 . The lower set screw section  254   b  has internal threads  262  and external threads  264 . External threads  266  of the second stage set screw  260  are received by the internal threads  262  so that the two-stage set screw  252  is provided as a nested couple. As seen in  FIG. 33 , the upper hex portion  254   a  is connected to the lower set screw section  254   b  by a thin break point  254   c  to enable the upper hex portion  254   a  to break away from the lower set screw section  254   b  at a desired torque. 
         [0056]    The two-stage set screw construction of the system  250  functions in the same manner as the single-stage set screw construct of the systems  10  and  200 , with the exception that the locking function can be completed in two phases via the two-stage set screw  252 . The first phase of the locking process locks the angulation/orientation of the tulip housing relative to the connector body, as well as the angulation/orientation of the connector body relative the screw post. The rod is free, such that the screw/connector sub-assembly can be rotated about the rod or translated along the rod for correction of the spine. This is accomplished by engaging the first stage set screw  254 . The second stage set screw  256  is then engaged and locked onto the rod  208 , once the user is satisfied with the desired spinal corrections. 
         [0057]    In operation, the first stage set screw  254  rests against the yoke  218 , while the second stage set screw  256  is nested inside it, not in contact with the rod  208 . Actuation of the yoke only will result in the previously-described first phase of the locking process. The second stage set screw  256  is then engaged to lock the rod  208  in place, as previously described. When locking is complete, the user will use an instrument to apply sufficient torque to break off the hex portion  254   a  of the first stage set screw  254 , such that the remaining portion is flush with the top of the tulip housing. 
         [0058]    The adjustments and movements as described previously for the system  10  and shown in  FIGS. 16-21  will be understood to be applicable to the system  250 . 
         [0059]    The foregoing description of preferred embodiments for this disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the disclosure and its practical application, and to thereby enable one of ordinary skill in the art to utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated.