Abstract:
A laminoplasty device including a superior attachment panel, inferior base panel, and a coupling screw for use in repair of lamina after spinal surgery. The interior of the fully assembled laminoplasty device contains a fusion corridor in which bone fusion material can be placed to facilitate regeneration of the lamina.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]     The present application is a nonprovisional patent application claiming benefit under 35 U.S.C. § 119(e) from U.S. Provisional Application Ser. No. 60/516,946, filed on Oct. 30, 2003, the entire contents of which are hereby expressly incorporated by reference into this disclosure as if set forth fully herein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     I. Field of the Invention  
         [0003]     The present invention relates generally to restoring the structural integrity of bone and more particularly, to repair and fusion of the lamina after spinal surgery.  
         [0004]     II. Discussion of the Prior Art  
         [0005]     Spinal stenosis is a condition in which the spinal canal has been narrowed or structured, and although it is a problem that occurs mostly in the aging population, it can also affect younger persons who have experienced certain types of trauma. The causes of spinal stenosis are many, but a partial list includes congenital stenosis, bone spurs, intervertebral disc herniation, ossification of the posterior longitudinal ligament or ligamentous flavum, and spondylosis. Often times patients with spinal stenosis, particularly the congenital type, will experience no symptoms until later in life. However, stenosis can cause myelopathy (a disease of the tissue surrounding the spinal cord) and myeloradiculopathy (disease of the spinal cord and/or nerve roots). Patients with either of these disorders may experience a wide range of symptoms, including pain in the upper body region (especially in cases of myeloradiculopathy), weakness in the hands, spastic or clumsy gait due to weakness in legs, and possibly urinary disorders, particularly a constant feeling of urgency.  
         [0006]     As a result of these spinal disorders, many patients experience a serious reduction in the ability to carry on everyday activities, and thus the problem must be treated. For people in which symptoms of stenosis are not as severe, or there is little to no pain involved, often times surgery is not required. These patients would be subject to conservative, non-surgical methods of treatment. For cervical stenosis, this usually involves wearing a rigid neck brace at night, and a soft brace during the day, so as not to impede normal activities more than is necessary. Other types of conservative treatment for cervical myelopathy include analgesia, physical therapy, and anti-inflammatory/steroid treatment. Conservative treatment for patients suffering from lumbar stenosis includes physical therapy and medication. If conservative treatment is unsuccessful, then surgery must be considered.  
         [0007]     The traditional surgical procedure for such a condition is laminectomy, or open decompression. In a laminectomy, the sipnous process and a portion of the lamina over the nerve root is removed in order to alleviate the pain. While this operation can be successful in solving the immediate problem (pain in the back, arms, or legs), the procedure itself creates its own set of problems. Removal of the lamina and sipnous process can weaken the stability of the spinal column, especially in elderly patients. Patients undergoing cervical laminectomy may experience postoperative kyphosis, or swan neck deformity, due to the removal of bone structure. Finally, many laminectomy patients develop a post-laminectomy membrane, or a formation of scar tissue involving the nerve root and surrounding structures. This is especially unfortunate because the scar tissue in effect puts pressure on the nerve that the surgical procedure was designed to alleviate.  
         [0008]     Another procedure used to alleviate nerve pinching is anterior cervical decompression and spinal fusion (ACDF). This procedure is used when a herniated disc is the cause of back pain. In this procedure, the offending disc is removed, thereby alleviating the pain. However, since the disc performs some structural function, spinal fusion is also employed to maintain the spatial integrity of the spinal column. As such, the spine becomes more rigid depending on how many discs need to be removed (and consequently how many vertebra need to be fused together). Patients undergoing ACDF may experience temporary hoarseness and difficulty swallowing due to irritation of the nerve leading to the vocal cords (recurrent laryngeal nerve) and esophagus caused by retraction during surgery.  
         [0009]     As a result of problems associated with laminectomy and ACDF, the laminoplasty was developed and is being used with increasing regularity. The primary advantages of laminoplasty are that it avoids complications associated with destabilization and immobilization of the spine, and eliminates the danger of post-laminectomy kyphosis and the post-laminectomy membrane. In a laminoplasty, the lamina on one side of the sipnous process is cut, but not removed. On the other side of the sipnous process, a groove is formed such that the lamina can swing posteriorly in a hinge-like manner. As a result of this, the procedure is often called “open-door laminoplasty.” The lamina can swing outward, creating more space in the spinal canal, thereby alleviating the pain caused by spinal stenosis.  
         [0010]     Because the lamina is not removed and the structural integrity of the spinal canal is intact, there is no need to fuse the vertebrae together. However, because one side of the lamina has been severed, there may be a problem with stability of the spine at that juncture. Thus, many techniques have developed in order to try to repair the lamina after laminoplasty. One such technique is to use a bone graft from another place, usually the hip, to act as a wedge between the open ends of the lamina. However, this method is unstable and can lead to slippage of the bone graft. Commonly, the ends of the severed lamina are held together with a wire device until the bone can regenerate itself, but this is also relatively unstable and can take time.  
         [0011]     The present invention is directed at overcoming, or at least improving upon, the disadvantages of the prior art.  
       SUMMARY OF THE INVENTION  
       [0012]     The present invention accomplishes this goal by providing a stabilizing device that encourages reformation of the lamina in its new position.  
         [0013]     According to one broad aspect of the present invention, the laminoplasty device comprises a superior attachment panel and an inferior base panel that are attached to each side of the laminal opening and are held together by a screw or bolt. When secured into place, the device forms an interior tunnel in which fusion material may be placed in order to regenerate the lamina.  
         [0014]     The superior attachment panel may include any number of components capable of creating a bridge over the post-laminectomy gap. By way of example only, the superior attachment panel may be composed of ceramic, steel, plastic, bone, or any other biocompatible material. The superior attachment panel may be shaped as a square, rectangle, or any other shape necessary to effectively bridge the gap. Preferentially, the superior attachment panel should contain a bore in the central region of the latitudinal surface, for the purpose of inserting a coupling screw. In addition to the coupling screw, the superior attachment panel may also contain any number of means of attachment to the inferior base panel, including but not limited to pegs of varying number, placement, length, and diameter. In a preferred embodiment, the bore may be threaded, but it is not necessary. The corners of the inferior face of the superior attachment panel may contain any number of means of attachment to the lamina to prevent slippage of the device. By way of example only, the attachment mechanism may consist of spikes or pegs, but a corrugated surface is also contemplated.  
         [0015]     The inferior base panel may include any number of components capable of creating a bridge over the post-laminectomy gap. By way of example only, the inferior base panel may be composed of ceramic, steel, plastic, bone, or any other biocompatible material. The inferior base panel may be shaped as a square, rectangle, or any other shape necessary to effectively bridge the gap, but should be in the same shape as the superior attachment panel. Preferentially, the inferior base panel should contain a threaded bore in the central region of the latitudinal surface, for the purpose of receiving a coupling screw. In addition to the coupling screw, the inferior base panel may also contain any number of means of attachment to the superior attachment panel, including but not limited to pegs of varying number, placement, length, and diameter. The corners of the superior face of the inferior base panel may contain any number of means of attachment to the lamina to prevent slippage of the device. By way of example only, the attachment mechanism may consist of spikes or pegs, but a corrugated surface is also contemplated.  
         [0016]     The fusion material may include any number of materials capable of facilitating fusion or regeneration of the lamina bone. By way of example only, the fusion material may include bone grafted from another part of the body, including but not limited to the hip bone. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     Many advantages of the present invention will be apparent to those skilled in the art with a reading of this specification in conjunction with the attached drawings, wherein like reference numerals are applied to like elements and wherein:  
         [0018]      FIGS. 1-2  are exploded perspective and perspective views, respectively, of a laminoplasty device according to the present invention;  
         [0019]      FIG. 3  represents the laminoplasty device of the present invention as finally inserted into the human vertebrae;  
         [0020]      FIGS. 4-6  illustrate alternative embodiments of the laminoplasty device of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]     Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The system and methods for restoring the structural integrity of bone disclosed herein boasts a variety of inventive features and components that warrant patent protection, both individually and in combination.  
         [0022]      FIGS. 1-2  illustrate a preferred embodiment of the laminoplasty device  10  of the present invention. The laminoplasty device  10  includes a superior attachment panel  20 , an inferior base panel  30 , and a coupling screw  40 . The superior attachment panel  20  is situated on one side of the lamina (See  FIG. 3 ), and includes a bore  22  that, in a preferred embodiment, includes threads  23 . Bore  22  is located in a relatively central location of superior latitudinal surface  21  of superior attachment panel  20 . Through bore  22  passes coupling screw  40 , which when attached with inferior base panel  30  will securely hold together the fully assembled laminoplasty device  10 . Inferior latitudinal surface  24  of superior attachment panel  20  contains spikes  25  located, in a preferred embodiment, at each of four corners of superior attachment panel  20 . It is contemplated that in alternative embodiments of laminoplasty device  10 , in which the shape of superior attachment panel  20  is other than rectangular or square, spikes  25  may be located in positions advantageously dictated by the shape of the panel.  
         [0023]     Attached to and extending perpendicularly from inferior latitudinal surface  24  of superior attachment panel  20  is the exterior fusion corridor housing  26 . Exterior fusion corridor housing  26  is a four-sided structure comprised of two opposing lateral corridor windows  27  and two opposing solid planar walls  28 . Superior attachment panel  20  forms the ceiling of the exterior fusion corridor housing  26 , while the floor is hollow to accommodate coupling with interior fusion corridor housing  36  and to allow coupling screw  40  to pass through. Shown in a square or cubic orientation, it is contemplated that exterior fusion corridor housing  26  could maintain a rectangular or other shape determined in part by the shape of superior attachment panel  20 .  
         [0024]     Inferior base panel  30  is situated on the other side of the lamina (See  FIG. 3 ), and includes a threaded bore  32  (not shown). Threaded bore  32  is located along the same longitudinal plane as bore  22  of superior attachment panel  20 , in order to effectively accommodate coupling screw  40 . Through bore  32  passes coupling screw  40 , which when attached with superior attachment panel  20  will securely hold together the fully assembled laminoplasty device  10 . Superior latitudinal surface  34  of inferior base panel  30  contains spikes  25  located, in a preferred embodiment, at each of four corners of the inferior base panel  30 . It is contemplated that in alternative embodiments of laminoplasty device  10 , in which the shape of the inferior base panel  30  is other than rectangular or square, spikes  25  may be located in positions advantageously dictated by the shape of the panel.  
         [0025]     Attached to and extending perpendicularly from superior latitudinal surface  34  of inferior base panel  30  is the interior fusion corridor housing  36 . The interior fusion corridor housing  36  is a four-sided structure comprised of two opposing lateral corridor windows  37  and two opposing solid planar walls  38 . Inferior base panel  30  forms the floor of interior fusion corridor housing  36 , while the ceiling contains a vertical corridor window  39  to allow coupling screw  40  to pass through. Shown in a square or cubic orientation, it is contemplated that interior fusion corridor housing  36  could maintain a rectangular or other shape determined in part by the shape of inferior base panel  30  and exterior fusion corridor housing  26 . When laminoplasty device  10  of the present invention is fully assembled, interior fusion corridor housing  36  will fit securely inside exterior fusion corridor housing  26 , forming the completed fusion corridor  60 , and allowing fusion material  50  (not shown) to fuse to the lamina and regenerate a solid bone structure (See  FIG. 2 ).  
         [0026]      FIG. 3  shows the fully assembled laminoplasty device  10  as it would appear installed in a human vertebra following laminoplasty surgery. Spikes  25  engage remaining lamina on either side of the gap, holding laminoplasty device  10  in place. Coupling screw  40  can be seen to extend completely through laminoplasty device  10 , originating at bore  22  (not shown) of superior attachment panel  20  and terminating at threaded bore  32  (not shown) of inferior base panel  30 .  
         [0027]      FIG. 4  represents an alternative embodiment  110  of the laminoplasty device  10  of the present invention. The laminoplasty device  110  includes a superior attachment panel  120 , an inferior base panel  130 , and a coupling screw  140 . The superior attachment peel  120  includes a bore  122  that, in a preferred embodiment, includes threads (not shown). Bore  122  is located in a relatively central location of superior latitudinal surface  121  of superior attachment panel  120 . Through bore  122  passes coupling screw  140 , which when attached with inferior base panel  130  will securely hold together the fully assembled laminoplasty device  110 . Inferior latitudinal surface  124  of superior attachment panel  120  may contain spikes (not shown) located, in a preferred embodiment, at each of four corners of the superior attachment panel  120 . It is contemplated that in alternative embodiments of laminoplasty device  110 , in which the shape of superior attachment panel  120  is other than rectangular or square, the spikes may be located in positions advantageously dictated by the shape of the panel.  
         [0028]     Superior attachment panel  120  may also contain any number of coupling orifices  126 , to mate with coupling projections  137  on inferior base panel  130 . In a preferred embodiment, the number of coupling orifices is two, and they are located to either side of the bore  122 , however it is contemplated that the number and location of coupling orifices may vary by design. When assembled with inferior base panel  130 , coupling orifices  126  function to prevent lateral movement of superior attachment panel  120 . Coupling orifices  126  may be of varying diameter, but must be consistent with the diameter of coupling projections  137 .  
         [0029]     Inferior base panel  130  includes a threaded bore  132  (not shown). Threaded bore  132  is located along the same longitudinal plane as bore  122  of superior attachment panel  120 , in order to effectively accommodate coupling screw  140 . Through bore  132  passes coupling screw  140 , which when attached with superior attachment panel  120  will securely hold together the fully assembled laminoplasty device  110 . Superior latitudinal surface  134  of inferior base panel  130  contains spikes  125  located, in a preferred embodiment, at each of four corners of inferior base panel  130 . It is contemplated that in alternative embodiments of laminoplasty device  110 , in which the shape of inferior base panel  130  is other than rectangular or square, spikes  125  may be located in positions advantageously dictated by the shape of the panel.  
         [0030]     Attached to and extending perpendicularly from superior latitudinal surface  134  of inferior base panel  130  are a pair of fusion corridor walls  136 . Fusion corridor walls  136  are comprised of two opposing solid planar walls  136 . Inferior base panel  130  forms the floor of fusion corridor  160 , while the ceiling is open until coupled with superior attachment panel  120 , at which point said superior attachment panel  120  will form the ceiling of fusion corridor  160 . Fusion corridor walls  136  may contain any number of coupling projections  137  extending perpendicularly from the top of fusion corridor walls  136 . Though the number, size, and location of coupling projections  137  may vary, they must be consistent with the number, size, and location of coupling orifices  126  on superior attachment panel  120 . When the laminoplasty device  110  of the present invention is fully assembled, coupling projections  137  will fit securely inside coupling orifices  126 , attaching superior attachment panel  120  and inferior base panel  130  in the proper alignment, and forming the completed fusion corridor  160 .  
         [0031]      FIG. 5  represents an alternative embodiment  210  of the laminoplasty device  10  of the present invention. The laminoplasty device  210  includes a superior attachment panel  220 , an inferior base panel  230 , and a coupling screw  240  (not shown). The superior attachment panel  220  includes a bore  222  that, in a preferred embodiment, includes threads  223 . Bore  222  is located in a relatively central location of superior latitudinal surface  221  of superior attachment panel  220 . Through bore  222  passes coupling screw  240  (not shown), which when attached with inferior base panel  230  will securely hold together the fully assembled laminoplasty device  210 . Inferior latitudinal surface  224  of superior attachment panel  220  may contain spikes  225  located, in a preferred embodiment, at each of four corners of the superior attachment panel  220 . It is contemplated that in alternative embodiments of laminoplasty device  210 , in which the shape of superior attachment panel  220  is other than rectangular or square, the spikes may be located in positions advantageously dictated by the shape of the panel.  
         [0032]     Superior attachment panel  220  may also contain any number of coupling indentations  226 , to mate with coupling projections  236  on inferior base panel  230 . In a preferred embodiment, the number of coupling indentations is two, and they are located to either side of the bore  222 , however it is contemplated that the number and location of coupling indentations may vary by design. When assembled with inferior base panel  230 , coupling indentations  226  function to prevent lateral movement of superior attachment panel  220 . Coupling indentations  226  may be of varying width, but must be consistent with the width of coupling projections  237 .  
         [0033]     Inferior base panel  230  includes a threaded bore  232  (not shown). Threaded bore  232  is located along the same longitudinal plane as bore  222  of superior attachment panel  220 , in order to effectively accommodate coupling screw  240  (not shown). Through bore  232  passes coupling screw  240  (not shown), which when attached with superior attachment panel  220  will securely hold together the fully assembled laminoplasty device  210 . Superior latitudinal surface  234  of inferior base panel  230  contains spikes  225  located, in a preferred embodiment, at each of four corners of inferior base panel  230 . It is contemplated that in alternative embodiments of laminoplasty device  210 , in which the shape of inferior base panel  230  is other than rectangular or square, spikes  225  may be located in positions advantageously dictated by the shape of the panel.  
         [0034]     A pair of fusion corridor walls  236  are attached to and extend perpendicularly from superior latitudinal surface  234  of inferior base panel  230 . Fusion corridor walls  236  are comprised of two opposing solid planar walls  236 . Inferior base panel  230  forms the floor of fusion corridor  260 , while the ceiling is open until coupled with superior attachment panel  220 , at which point said superior attachment panel  220  forms the ceiling of fusion corridor  260 . Fusion corridor walls  236  may contain any number of coupling projections  237  extending perpendicularly from the top of fusion corridor walls  236 . Though the number, size, and location of coupling projections  237  may vary, they must be consistent with the number, size, and location of coupling indentations  226  on superior attachment panel  220 . When the laminoplasty device  210  of the present invention is fully assembled, coupling projections  236  will fit securely inside coupling indentations  226 , attaching superior attachment panel  220  and inferior base panel  230  in the proper alignment, and forming the completed fusion corridor  260 .  
         [0035]      FIG. 6  illustrates yet another embodiment  310  of the laminoplasty device  10  of the present invention. The laminoplasty device  310  includes a superior attachment panel  320 , an inferior base panel  330 , and a coupling screw  340  (not shown). The superior attachment panel  320  is includes a bore  322  that, in a preferred embodiment, includes threads  323 . Bore  322  is located in a relatively central location of superior latitudinal surface  321  of superior attachment panel  320 . Through bore  322  passes coupling screw  340  (not shown), which when attached with inferior base panel  330  will securely hold together the fully assembled laminoplasty device  310 . Inferior latitudinal surface  324  of superior attachment panel  320  contains spikes  325  (not shown) located, in a preferred embodiment, at each of four corners of superior attachment panel  320 . It is contemplated that in alternative embodiments of laminoplasty device  310 , in which the shape of superior attachment panel  320  is other than rectangular or square, spikes  325  may be located in positions advantageously dictated by the shape of the panel.  
         [0036]     Superior attachment panel  320  may also contain any number of coupling orifices  326 , to mate with coupling projections  336  on inferior base panel  330 . In a preferred embodiment, the number of coupling orifices is four, and they are located to either side of bore  322 , however it is contemplated that the number and location of coupling orifices may vary by design. When assembled with inferior base panel  330 , coupling orifices  326  function to prevent lateral movement of superior attachment panel  320 . Coupling orifices  326  may be of varying diameter, but must be consistent with the diameter of coupling projections  337 .  
         [0037]     Inferior base panel  330  includes a threaded bore  332  (not shown). Threaded bore  332  is located along the same longitudinal plane as bore  322  of superior attachment panel  320 , in order to effectively accommodate coupling screw  340  (not shown). Through bore  332  passes coupling screw  340  (not shown), which when attached with superior attachment panel  320  will securely hold together the fully assembled laminoplasty device  310 . Superior latitudinal surface  334  of inferior base panel  330  contains spikes  325  located, in a preferred embodiment, at each of four corners of the inferior base panel  330 . It is contemplated that in alternative embodiments of laminoplasty device  310 , in which the shape of the inferior base panel  330  is other than rectangular or square, spikes  325  may be located in positions advantageously dictated by the shape of the panel.  
         [0038]     Attached to and extending perpendicularly from superior latitudinal surface  334  of inferior base panel  330  is fusion corridor housing  336 . Fusion corridor housing  336  is a four-sided structure comprised of two opposing lateral corridor windows  339  and two opposing solid planar walls  338 . Inferior base panel  330  forms the floor of fusion corridor housing  336 , while the ceiling contains a vertical corridor window  335  to allow coupling screw  340  (not shown) to pass through. Shown in a square or cubic orientation, it is contemplated that fusion corridor housing  336  could maintain a rectangular or other shape determined in part by the shape of inferior base panel  330 . Fusion corridor housing  336  may contain any number of coupling projections  337  extending perpendicularly from the top of fusion corridor housing  336 . Though the number, size, and location of coupling projections  337  may vary, they must be consistent with the number, size, and location of coupling orifices  326  on superior attachment panel  320 . When the laminoplasty device  310  of the present invention is fully assembled, coupling projections  337  will fit securely inside coupling orifices  326 , attaching superior attachment panel  320  and inferior base panel  330  in the proper alignment.  
         [0039]     Referring back to  FIG. 1 , the previously described preferred embodiment of laminoplasty device  10  indicates that bore  22  in superior attachment panel  20  contains threads  23 , and inferior base panel  30  contains threaded bore  32 . Thus, in the preferred embodiment, both bore  22  and threaded bore  32  contain threads for securing coupling screw  40 . It is contemplated that it may be advantageous for one of the aforementioned bores to be smooth rather than threaded. Thus, in alternative embodiments in which coupling screw  40  is inserted in a superior to inferior direction (that is, passing first through bore  22  and then through threaded bore  32 ), bore  22  may or may not contain threads. Similarly, in alternative embodiments in which coupling screw  40  is inserted in an inferior to superior direction, bore  32  may be without threads, but then bore  22  would be threaded in order to secure coupling screw  40 . This alternative approach to securing coupling screw  40  is intended to also apply to the corresponding bores  122 ,  132 ,  222 ,  232 ,  322 ,  332  and screws  140 ,  240 ,  340  in respective alternative embodiments  110 ,  210 , and  310 , and as illustrated in  FIGS. 4-6 .