Abstract:
A device for covering and protecting the spinal cord of a patient after some or all of the spinous process or lamina has been removed. The device includes a main body adjustably attached to at least two rod attachment flanges such that each rod attachment flange may be adjusted closer and further from the main body. The rod attachment flanges are each attached to a pedicle rod having at least four pedicle screws attached thereto. The pedicle attachment screws are adapted for attachment to at least one vertebrae of the patient.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Patent Application Ser. No. 61/138,022 filed Dec. 16, 2008, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to the field of spinal fusion and more specifically to instrumentation for spinal fusion and maintenance of the musculature around the spine. 
       BACKGROUND OF THE INVENTION 
       [0003]    Spinal fusion is a surgical technique used to combine two or more vertebrae. Supplementary bone tissue (either autograft or allograft) is used in conjunction with the body&#39;s natural osteoblastic processes. This procedure is normally used to eliminate the pain caused by abnormal motion of the vertebrae by immobilizing the vertebrae themselves. 
         [0004]    Spinal fusion is performed most commonly in the lumbar region of the spine, but it is also used to treat cervical and thoracic problems. Patients requiring spinal fusion have either neurological deficits or severe pain which has not responded to conservative treatment. 
         [0005]    There are two main types of lumbar spinal fusion, which may be used in conjunction with each other: 
         [0006]    Posterolateral fusion places the bone graft between the transverse processes in the back of the spine. These vertebrae are then fixed in place with screws and/or wire through the pedicles of each vertebra attaching to a metal rod on each side of the vertebrae. 
         [0007]    Interbody fusion places the bone graft between the vertebra in the area usually occupied by the intervertebral disc. In preparation for the spinal fusion, the nucleus pulposus is removed entirely. A device may be placed between the vertebra to maintain spine alignment and disc height. The intervertebral device may be made from either plastic or titanium. The fusion then occurs between the endplates of the vertebrae. Using both types of fusion is known as 360-degree fusion. Fusion rates are higher with interbody fusion. 
         [0008]    In most cases, the fusion is augmented by a process called fixation, meaning the placement of metallic screws (pedicle screws often made from titanium), rods or plates, or cages to stabilize the vertebra to facilitate bone fusion. The fusion process typically takes 6-12 months after surgery. 
         [0009]    Spinal instrumentation and fusion are not new surgical concepts. Although the first spinal fusion was performed almost 90 years ago, Dr. Paul Harrington developed spinal instrumentation in the late 1950&#39;s. It is estimated that roughly 220,000 Americans undergo spinal fusion each year. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    The present invention comprises a device for covering and protecting the spinal cord of a patient after some or all of the spinous process or lamina has been removed. The device comprises a main body adjustably attached to at least two rod attachment flanges such that each rod attachment flange may be adjusted closer and further from the main body. The rod attachment flanges are each attached to a pedicle rod having at least four pedicle screws attached thereto. The pedicle attachment screws are adapted for attachment to at least one vertebrae of the patient. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]      FIG. 1  is an end view of an improved device for spinal fusion according to a first embodiment of the present invention; 
           [0012]      FIG. 2  is a side view of an improved device for spinal fusion according to a first embodiment of the present invention; 
           [0013]      FIG. 3  is a perspective view of an improved device for spinal fusion according to a first embodiment of the present invention; 
           [0014]      FIG. 4  is an end view of an improved device for spinal fusion according to a second embodiment of the present invention; 
           [0015]      FIG. 5  is a side view of an improved device for spinal fusion according to a second embodiment of the present invention; 
           [0016]      FIG. 6  is a perspective view of an improved device for spinal fusion according to a second embodiment of the present invention; 
           [0017]      FIG. 7  is a perspective view of an improved device for spinal fusion according to a second embodiment of the present invention; 
           [0018]      FIG. 8  is a close up view of an improved device for spinal fusion according to a second embodiment of the present invention; 
           [0019]      FIG. 9  is an exploded view of an improved device for spinal fusion according to a second embodiment of the present invention; 
           [0020]      FIG. 10  is a close up view of an improved device for spinal fusion according to a third embodiment of the present invention; 
           [0021]      FIG. 11  is a perspective view of an improved device for spinal fusion according to a third embodiment of the present invention; 
           [0022]      FIG. 12  is a side view of an improved device for spinal fusion according to a third embodiment of the present invention; 
           [0023]      FIG. 13  is an end view of an improved device for spinal fusion according to a third embodiment of the present invention; and 
           [0024]      FIG. 14  is an exploded view of an improved device for spinal fusion according to an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. 
         [0026]    The present invention comprises an improved instrumentation for spinal fusion that is fully adjustable and provides a sloped roof and muscle attachments for maintaining musculature in proper position and away from the spinal cord after surgery. The device includes an anatomically shaped arch that covers and protects the spinal cord after some or all of the spinous process and lamina have been removed. 
         [0027]    In that regard and referring to  FIGS. 1-3 , an embodiment of the present invention is shown. The embodiment includes a main body  10  which is arch-shaped and includes an extension portion  12  extending outwardly therefrom. The extension portion defines a plurality of bores  14  which may be used for suture attachment. Rod attachment flanges  20  are adjustably attached to opposite sides  16  and  18  of the main body  10 . An extension  22  of each of the rod attachment flanges  22  is received in a slot formed within the sides  16  and  18  of the main body. Set screws  24  threaded into the top  26  of the main body  10  fix the extensions  22  in a desired location. 
         [0028]    Attached to each extension  22  of the rod attachment flanges  20  is a pedicle rod attachment portion  28 . In a preferred embodiment, a pedicle rod  34  is maintained in position by the pedicle rod attachment portion  28  by use of set screws  32  that thread into the pedicle rod attachment portion  28 . The set screws  32  when tightened exert a clamping action on the pedicle rod  34  to maintain the pedicle rod  34  and the pedicle rod attachment portion  28  in a fixed relationship. When loosened, the set screws  32  release the clamping force and allow the pedicle rod  34  to move to be moved axially within the pedicle rod attachment portion  28  for adjustment of the location of the main body  10  with respect to pedicle screws  30  (described further below). 
         [0029]    Further attached to each pedicle rod  34  are a pair of pedicle screw attachment flanges  36 . The pedicle screw attachment flanges  36  attach pedicle screws to the main body  10  by utilizing set screws  38  to both clamp onto the pedicle rod  34  and maintain each pedicle screw  30  in a fixed relationship to the main body  10  when the set screw  38  is tightened. When the set screw  38  is loosened the pedicle screw  30  may be moved to adjust the angle of the pedicle screw  30  to the pedicle screw attachment flange  36 . Additionally, when the set screw  38  is loosened, the pedicle screw attachment flange  36  and pedicle screw  30  combination may be moved axially along the pedicle rod  34  to adjust the location of the pedicle screw  30  with respect to the other screws  30  and with respect to the main body  10 . The main body most preferably comprises an inert material or comprises a coating suitable for placement within the human body, and more preferably comprises a coating of a flexible, inert, medical-grade silicone elastomer. One example of a suitable elastomer is available under the trademark SILASTIC available from the Dow Corning Company of Midland, Mich. The coating also preferably comprises a growth factor to promote both bone and musculature regeneration and healing. 
         [0030]    Referring to  FIGS. 4-7 , there is provided another embodiment of the present invention. The second embodiment comprises a modular main body  110  comprising hinged members  112 ,  114  and  116 . The hinged members are attached by interdigitated hinge legs  118  and a hinge pin comprising a screw  119  that threads into a nut or into an end hinge leg  118 . Most preferably, the nut  121  comprises a tapered nut (see  FIG. 9 ) within a tapered bore of a hinge leg  118 . The nut may further comprise projections  123  that prevent the screw  119  and nut  121  from inadvertently loosening. A first hinge member  112  comprises an extension portion  120 , and second and third hinge members  114  and  116  comprise a main body  122 . When the screw  119  is tightened, the interdigitated legs  118  are forced into a clamped relationship preventing relative rotation of the hinged members  112 ,  114  and  116  with respect to one another. When the screw  119  is loosened, the hinged members  112 ,  114  and  116  are allowed to rotate relative one another for adjustment of their relative angle. 
         [0031]    Extending from the main body  122  are extensions  124  that preferably comprise ball-headed extensions. The extensions  124  are located within extension bores  126  defined by the main body  122 . Set screws  128  are located in threaded bores  130  that intersect with the extension bores  126 . When the set screws  128  are tightened, they exert a clamping action on the extensions  124  to lock the extensions  124  in place. When the set screws  128  are loosened, they allow the extensions  124  to move axially within the bores  130  for adjustment of the width of the device. 
         [0032]    Further, attached to the extensions  124  are adjustable sockets  132  for lockably capturing the extensions  124 . Preferably, the sockets  132  each comprise a body portion  134  having a mating surface  136  and a threaded collar  138  for threading onto a threaded outer surface of the body portion  134 . When the collar  138  is tightened it exerts a clamping force on the extension  124 , thereby maintaining the body portion  134  in a fixed relationship with the extension  124 . When the collar  138  is loosened, the body portion  134  is movable with respect to the extension  124  such that the relative angle of the body portion  134  to the extension  124  can be manipulated. 
         [0033]    The body portion  134  further comprises a cylindrical end  140  that extends into a clamp section  142 . The clamp section  142  includes a fastener  144  that when tightened affixes the cylindrical end  140  to the clamp section  142  and when loosened allows axial movement of the cylindrical end  140  with respect to the clamp section  142  thereby, with the extensions  124 , allowing for width adjustment of the device. 
         [0034]    Attached to the clamp section  142  is another collar  148  and socket  146  arrangement. The collar  148  is attached to the clamp section  142  and the socket  146  defines a bore  150  through which a fastener  152  may be threaded into a pedicle screw  154 . The socket  146  further defines a bore  156  through which the fastener  152  attaches to the pedicle screw  154 . The bore  156  is sized such that when the fastener  152  is loosened in the pedicle screw  154  the angle of the pedicle screw  154  within the socket  146  may be adjusted within a range of adjustment. When the fastener  152  is tightened within the pedicle screw  154  the angle of the pedicle screw  154  within the socket  146  is fixed at the desired angle. 
         [0035]    Further, the socket  146  defines openings  156  at opposite ends thereof through which a pedicle rod  158  may be inserted. The socket  146  further includes a pedicle rod mating surface  160  upon which pedicle rod  158  rests. When rotating the collar  148  to tighten it upon the socket  146 , the collar  148  performs a clamping action upon the pedicle rod  158  to clamp the socket  146  into a fixed relationship with the pedicle rod  158 . When the collar  148  is loosened, the socket  146  may be adjusted along the axis of the pedicle rod  158  and rotated around the circumference of the pedicle rod  158 . 
         [0036]    Referring to  FIG. 10-14 , in yet another embodiment of the present invention, the clamp section  142  and corresponding collar  148 /socket  146 /pedicle rod  158  arrangement may be utilized upon a main body  200  that incorporates cutout sections  202 ,  204 ,  206  and  208 . Within the cutout sections  202 - 208  are located extensions  210  formed in a configuration to match a curvature of the main body  200  and then extend outwardly in the form of cylindrical ends  212  from the main body  200  in two opposed directions. The clamping sections  142  are then attached to the cylindrical ends  212  as with the cylindrical ends  140 . 
         [0037]    The extensions  210  are attached to the main body  200  by inserting main body ends  214  of the extensions  210  into corresponding bores  216  within the main body  200 . Set screws  218  threaded into bores  220  when tightened clamp down the extensions  210  in a fixed position and when loosened allow the extensions to be moved axially with respect to the main body ends  214 . Additionally, set screws  222  threaded into bores  224  act as bump stops to prevent inadvertent disassociation of the extensions  210  from the main body  200  due to slippage or loosening set screws  218 . 
         [0038]    By utilizing any of the present embodiments, a surgeon may perform a spinal fusion and place the present device upon the spine of a patient by adjusting the dimensions of the device to particularly fit the dimensions of the spine of the particular patient.