Abstract:
A device for reducing a stabilization member into the head of a medical implant is provided. The device includes a first jaw for engaging the implant underneath the implant head. A second jaw is provided for engaging the stabilization number. The second jaw is slideably mounted with respect to the first jaw and is movable with respect to the first jaw to reduce the stabilization member within the head of the implant

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to reducing devices used for reducing stabilization members such as rods or plates into medical implants such as pedicle screws or lamina hooks. 
       BACKGROUND OF THE INVENTION 
       [0002]    Spinal surgeons often treat spinal disorders with spinal fusion augmented with stabilization members such as plates or elongated spinal rods connected to the spine with implants such as pedicle screws or lamina hooks. Such “stabilization assemblies” often comprise one or two spinal rods or plates and a plurality of implants engaging the pedicles of their respective vertebral bodies. The implants are provided with U-shaped heads that can be capped to couple the stabilization members to the implants or with threaded heads that can be threadably connected to the stabilization members with fasteners. During the surgical procedure to couple the stabilization member to the implants, it is often necessary to use a tool or device to push or “reduce” the stabilization member with the implant heads. It is desirable that such a device offers the surgeon a significant mechanical advantage in the reduction procedure. 
       SUMMARY OF THE INVENTION 
       [0003]    To make manifest the above noted and other manifold desires, a revelation of the present invention is brought forth The present invention provides a device for reducing a stabilization member into the head of a medical implant. The device includes a first jaw for engaging the implant underneath the implant head. A second jaw is provided for engaging the stabilization number. The second jaw is slideably mounted with respect to the first jaw and is movable with respect to the first jaw to reduce the stabilization member with the head of the implant. 
         [0004]    Other features of the invention will become more apparent to those skilled in the art as the invention is further revealed in the accompanying drawings and Detailed Description of the Invention. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a schematic perspective view of a preferred embodiment reducing device of the present invention being utilized with a pedicle screw and a rod implant. 
           [0006]      FIG. 1A  is a schematic side elevational view of the reducing device of  FIG. 1  being utilized with a lamina hook and a rod implant 
           [0007]      FIG. 2  is a schematic side elevational view of the reducing device of  FIG. 1 . 
           [0008]      FIG. 3  is a schematic perspective view of a preferred embodiment reducing device of the present invention being utilized with a pedicle screw and a plate implant. 
           [0009]      FIG. 4  is a schematic side elevational view of the reducing device shown in  FIG. 3 . 
           [0010]      FIG. 5  is a schematic side elevational view of an embodiment of the present invention. 
           [0011]      FIG. 6  is a view taken along line  66  of  FIG. 5 . 
           [0012]      FIG. 7  is a schematic side elevational view of an embodiment of the present invention. 
           [0013]      FIG. 8  is a schematic side elevational view of an embodiment of the present invention. 
           [0014]      FIG. 9  is a schematic side elevational view of an embodiment of the present invention. 
           [0015]      FIG. 10  is a schematic side elevational view of an embodiment of the present invention. 
           [0016]      FIG. 11  is a schematic perspective view of an alternate embodiment first jaw of the present invention reducing device. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIGS. 1 and 2  schematically illustrate a device  7  for reducing a stabilization member  10  with the head  12  of an implant pedicle screw  14 .  FIG. 1A  schematically illustrates a device  7  for reducing a stabilization member  10  with the head  12  of an implant lamina hook  15 . The device  7  has a first jaw  16 . The first jaw  16  has two arms  18  forming an opening or slot  20  ( FIG. 3 ) therebetween. The first jaw  16  engages the pedicle screw  14  underneath its head  12  on a stem portion  22  of the pedicle screw or upon a threaded portion  24 . In a similar manner, the first jaw  16  engages the lamina hook  15  underneath its head  12 . 
         [0018]    An implant  14  utilized with the reducing device  7  of the present invention can have a head  12  with two posts  26  juxtaposed by a stabilization member receiving section  28 . In other applications the implant  29  can have a head providing by an enlargement  30  ( FIG. 3 ) crowned by a threaded post  32 . A stabilization member can be an elongated member such as a cable or rod  10  ( FIGS. 1 and 2 ) or a plate  36  preferably having a slot  38  ( FIGS. 3 and 4 ). 
         [0019]    Slideably mounted with respect to the first jaw  16  is a second jaw  40 . The second jaw  40  as shown in  FIGS. 1 and 2  has two widely spaced apart arms  42  with a slot or opening  44  therebetween to allow the arms to be juxtaposed by the implant head  12 . The second jaw  48  as shown in  FIGS. 3 and 4  have two arms  50  with a more narrow opening or slot  52  there between to more closely align with the juxtaposing threaded post  32 . 
         [0020]    In the example shown in  FIGS. 5 and 6 , the second jaw  40  has a tongue and groove type connection  60  with the first jaw  16 . A three pivot point lever mechanism  62  is provided to move the second jaw  40  with respect to the first jaw  16 . The lever mechanism  62  includes a two bar linkage provided by a handle  64  and pivot link  66 . 
         [0021]    Referring to  FIG. 7 , a lever mechanism  70  has a pin and slot arrangement to move the second jaw  40  with respect to the first jaw  16 . A handle  72  has a slot  74  capturing a pin  76 . The pin  76  is fixedly connected with a second jaw  40 . In another embodiment (not shown), the pin can be connected with the handle  72  and a slot can be provided in the second jaw  40 . 
         [0022]    Referring to  FIG. 8 , the rack and pinion mechanism  82  is used to move the second jaw  40  with respect to the first jaw  16 . The pinion  84  can be turned by hand or it can be motorized. The pinion  84  engages a rack  86  connected with the second jaw  40 . In another embodiment (not shown), the pinion can be connected with the second jaw  40  and the rack can be connected with the first jaw  16 . 
         [0023]    Referring to  FIG. 9 , a jackscrew mechanism  90  is utilized to move the second jaw  40  with respect to the first jaw  16 . A threaded cylinder  92  provides an upper portion of the second jaw. The cylinder  92  is encircled by an internally threaded drum  96  that can be rotated to translate the second jaw  40 . Additionally the second jaw  40  has an indention  98  to provide a better grip of the stabilization number such as a rod  10  or a portion of the implant head. A similar or identical indention can also be used on the second jaw of the prior or later describe embodiment reducing devices to facilitate a better grip of the stabilization member or implant head. 
         [0024]      FIG. 10  illustrates an embodiment of the present invention with a ratchet mechanism  110  to adjustably lock the position of the second jaw  40  with respect to the first jaw  16 . The ratchet mechanism  110  has a paw  112  that by gravity or by a spring loading can be torsionally biased to engage with a rack  114 . The ratchet mechanism  110  can be used alone or in conjunction with the movement mechanisms should described in  FIGS. 5 ,  7 ,  8  and  9 . 
         [0025]      FIG. 11  illustrates a first jaw  16  with a tapered opening  128  to allow the jaw  16  to align more closely with the implant head or with a screw thread of the threaded portion  24  of the pedicle screw. 
         [0026]    The embodiment of the present invention shown in  FIGS. 5 to 10  can also utilize a second jaw  48  as shown in  FIGS. 3 and 4 . While preferred embodiments of the present invention have been disclosed, it is to be understood it has been described by way of example only and that various other modifications can be made to the present invention without departing from the spirit and scope of the invention as it is encompassed in the following claims.