Abstract:
Provided is a system and devices for use in the treatment and repair of moveable skeletal joints in the body of a subject. In particular, the present invention relates to the complete or partial posterior modular disc replacement of damaged or diseased fibrocartilage intervertebral discs in a subject wherein the replacement disc is capable of rotation and translation articulation.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to devices, methods, and systems for the treatment and repair of moveable skeletal joints in the body of a subject. In particular, the present invention relates to the complete or partial replacement of diseased or damaged fibrocartilage components of the skeletal joints. More particularly, the present invention relates to complete or partial posterior modular disc replacement of damaged or diseased fibrocartilage intervertebral discs in a subject using a novel device and methods.  
         [0003]     2. Background of the Technology  
         [0004]     Mechanical back pain is the most common and costly musculoskeletal condition affecting middle-aged humans. Such back pain can be caused by several factors to include Degenerative Disc Disease.  
         [0005]     Many devices have been invented for the purpose of stabilizing and/or replacing parts of the disc in an effort to ease the pain associated with disc disease. Many of the devices used and procedures necessary to install such devices in a patient have been extremely invasive requiring anterior access and exposure with resulting discomfort, unexpected complications, and prolonged recovery and pain. Examples of such devices and methods are found in U.S. Pat. No. 6,712,853 issued to Kuslich, U.S. Pat. No. 5,888,220 issued to Felt et al., U.S. Pat. No. 6,863,688 issued to Ralph et al., U.S. Pat. No. 6,887,272 issued to Ralph et al., and U.S. Pat. No. 6,899,735 issued to Coates et al.  
         [0006]     While efforts to minimize the invasive nature of the procedure necessary to effect disc replacement have been made, such as U.S. Pat. No. 5,171,280 issued to Bumgartner, the resulting replacement disc has been less than satisfactory for the patients long term benefit. Thus a need exist for a system and method for providing a minimally invasive, effective, safe disc replacement.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention provides a novel system for the repair or replacement of all or part of the fibrocartilage elements of the moveable skeletal joints in the body of a subject.  
         [0008]     Also provided is a system and method of use for the complete or partial replacement of diseased or damaged fibrocartilage components of the skeletal joints.  
         [0009]     Also provided is a system for posterior modular disc replacement for damaged or diseased fibrocartilage intervertebral discs in a subject.  
         [0010]     Also provided is a method of using the assembly of the invention such that minimal time and effort is required to set the disc replacement device in the desired position relative to the anatomy of the subject.  
         [0011]     Also provided is a kit that includes the assembly of the invention and surgical instruments necessary for placement of the device of the present invention in a subject.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, wherein:  
         [0013]      FIG. 1  provides a frontal perspective view of the one embodiment of the novel posterior modular disc replacement system of the present invention, showing the guide wire with a blunt tip, an end plate in the closed configuration inserted over on the guide wire, an insertion cannula through which the guide wire is slidably passed, a spreader bearing inserted over the guide wire, and an insertion tool threaded on the guide wire,  
         [0014]      FIG. 2A -B provides a frontal and side view of the novel end plate element of the present invention in a closed configuration,  
         [0015]      FIG. 3A -B provides a frontal and side view of the end plate of the present invention in a spread configuration with the spreader bearing inserted therein,  
         [0016]      FIG. 4  provides a frontal perspective view of the end plate of the present invention in a spread configuration with the spreader bearing inserted therein,  
         [0017]      FIG. 5  provides a cross-sectional frontal view of an alternative embodiment of the system of the present invention having an at least partially threaded guide wire, at least one locking element configured to be releasably locked on the guide wire, and a spacer element configured to be positioned between two end plates,  
         [0018]      FIG. 6  provides a side view of an alternative guide wire of the present invention having a spherical head element,  
         [0019]      FIG. 7  provides a side view of an alternative guide wire assembly of the present invention having a first and a second guide wire that can be releasably attached one to the other,  
         [0020]      FIG. 8  provides a perspective view of a guide wire slidably passed through an end plate of the present invention in a closed position, wherein the end plate is releasably held in the closed position by at least one banding element,  
         [0021]      FIG. 9A  provides a top view of a vertebra and shows a properly positioned guide wire of the present invention as well as the alternative embodiment of having a guide wire assembly of a first and second guidewire that can be releasably attached one to the other,  
         [0022]      FIG. 9B  shows a side view of two adjacent vertebral bodies and the relative position of an insertion cannula and guide wire of the present invention,  
         [0023]      FIG. 9C  shows a top view of a vertebra having two end plates in closed configuration positioned adjacent thereto and  FIG. 9D  shows a side view of the end plates in a closed configuration relative to two adjacent vertebral bodies,  
         [0024]      FIG. 9E -F shows a top and side view of vertebra with two end plates in a spread configuration with each containing a respective spreader bearing,  
         [0025]      FIG. 10A -V provides a series of views of a vertebra having the assembly of the present invention and elements thereof positioned relative to the vertebra to demonstrate the sequential operation of the present invention with  FIGS. 10G and 10I  showing an alternative embodiment of an insertion cannula with a guide wire scooping element for directing the path of a guidewire.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     Detailed embodiments of the present invention are disclosed herein; however, it is understood that the following description is provided as being exemplary of the invention, which may be embodied in various forms without departing from the scope of the claimed invention. Thus, the specific structural and functional details provided in the description of a posterior modular disc replacement are non-limiting, but serve merely as a basis for the invention defined by the claims provided herewith. The system as described below can be modified to provide replacement of joint components for other moveable skeletal joints in a subject without departing from the concept of the invention.  
         [0027]     The present invention provides a system and a minimally invasive method for using the apparatus of the system to effect posterior modular disc replacement. The method and apparatus of the present invention is more easily and expeditiously accomplished with minimal risk and improved safety for the subject over conventional disc replacement apparatus and procedures.  
         [0028]     With reference to  FIGS. 1-10V , the present invention is a novel posterior modular disc replacement system. As best shown in  FIG. 1  the system, generally shown at  10 , includes a guide wire  12 , an insertion cannula  14 , having a first cannula opening  16  and a second cannula opening  18  connected one to the other by a cannula lumen  20 , which is sized and configured to allow easy passage of the guide wire  12  along the cannula longitudinal axis. Also included in the system of the present invention is at least one end plate  22 , which is sized and configured so as to be capable of passage over the guide wire  12  and through the lumen  20  of the insertion cannula  14 . A spreader bearing  24 , is sized and configured to be capable of passage over the guide wire  12  and through the lumen  20  of the insertion cannula  14 . The spreader bearing  24  can include a first and second guide wire portal  26 ,  28 , which are respectively disposed at opposing ends of the spreader bearing  24  and are connected by a spreader bearing lumen  30 , which is sized so as to permit the spreader bearing  24  to pass over the guide wire  12 . The guide wire  12  can terminate at the insertion end with a blunt tip  32 , as shown in  FIG. 1  or alternatively with a spherical guide wire head  64  as best shown in  FIGS. 5, 6 , and  9 A. An insertion tool  34  is configured for manual control by a user and is provided with an insertion tool lumen  36 , which extends along the longitudinal axis of the insertion tool terminating at each end in an first and second external opening  40 ,  42 .  
         [0029]     In practice, as best demonstrated in FIGS.  9 A-F and FIGS.  10 A-V, the guide wire is inserted between two adjacent vertebra so as to be properly positioned to facilitate a posterior modular disc replacement. As best shown in  FIG. 10C -F, the guide wire can be biased to facilitate the user&#39;s movement of the guidewire in the desired direction. As shown in  FIG. 9A , the guide wire  12  placement can be accomplished using one guide wire or alternative by using a first and second guide wire component  58 ,  60  that can be releasably connected one to the other at a guide wire attachment point  62 . Any releaseable attachment mechanism such as quick release, bayonet fitting, leur-lock type, or other screw-type fitting can be used as a releaseable attachment mechanism. As illustrated in FIGS.  9 C-D, one or more (preferably two) end plates  22  in a closed configuration can be threaded along the guide wire  12  into the desired position to effect posterior modular disc replacement. Once the end plate  22  is in position, a spreader bearing  24  can be threaded along the guide wire and positioned withing the end plate  22  as best shown in FIGS.  9 E-F. Once positioned and in a spread configuration, the end plates  22  of the present invention provide a minimally invasive, safe, and effective posterior modular disc replacement.  
         [0030]     To attain effective, safe disc replacement, the novel system of the present invention provides each of the system elements shown in  FIG. 1 . The system of the present invention can be employed as described above and illustrated in FIGS.  9 A-F and FIGS.  10 A-V. The ability of the system of the present invention to easily move the components into position and then secure the replacement disc into a proper position is central to the present invention advantages. As best shown in  FIG. 2A -B, the novel end plate  22  of the present invention is configured as having a first and a second end plate opposing body  44 ,  46 , which may or not be virtual mirror-images. The exterior of the end plate  22  can incorporate gripping elements such as a textured, ridged, or ribbed surface as an aid to maintaining good contact and relative position to the vertebral body. The opposing bodies  44 ,  46  of the end plate  22  can be connected one to the other or can be held in relative position, one to the other, by a variety of means. For example, the opposing bodies  44 ,  46  can be connected along one or more edges by a break-awayjoint  48 , which is composed of such material as to permit the opposing bodies  44 ,  46  to be separated one from the other with a predetermined amount of mechanical force. Importantly, the breakaway joint should be of sufficient strength to retain the opposing bodies in relative position one to the other until the user of the system elects to forcibly fracture the breakaway joint  48  by manual application of force. It is within the concept of the invention that the breakaway joint can alternatively be broken chemically, thermally, photolytically, or by other means known for disassociating two portions one from the other. The manual exertion of force to fracture the breakaway joint is accomplished by the user employing the insertion tool to physically move the spreader bearing  24  along the guide wire  12  to the point that it makes contact with the end plate  22 . The relative contact points of the spreader bearing  24  and the end plate  22  are relatively complementary one to the other, such as for example, a convex surface  50  on the end of the spreader bearing  24  abutting against a concave surface  52  on the end of the end plate  22 . In operation, when the convex surface  50  of the end of spreader bearing  24  is manually forced against the concave surface  52  of the end plate  22 , the first and second opposing bodies  44 ,  46  of the end plate  22  are forced apart. This act of manually forcing apart the opposing bodies  44 ,  46  serves to alter the configuration of the end plate from a closed configuration to a spread configuration. The surfaces of the opposing bodies  44 ,  46 , which directly oppose each other are configured to define a spreader bearing seat  56 , which may or may not resemble a concavity. As the opposing bodies  44 ,  46  of the end plate  22  are moved into the spread configuration, as best shown in  FIGS. 3A-3B , the spreader bearing  24  is positioned in the spreader bearing seat  56  so as to securely hold the end plate in the spread configuration. In the spread configuration, the end plate  22  is securely butted against the opposing surfaces of the two adjacent vertebra thus providing a secure, effective disc replacement. As the gripping elements  23  of the opposing bodies  44 ,  46  provide a secure contact with the bone surface, the spreader bearing  24  positioned within the spreader bearing seat provides an articulation surface between the opposing inner surfaces of the two opposing bodies  44 ,  46 . The end plate thus provides a securely seated modular disc replacement capable of rotation and translation.  
         [0031]     Additional embodiments of the present invention are within the concept of the invention and can be employed as the user finds advantageous to the circumstance. Alternative guide wire heads, such as, for example, the spherical guide wire head  64  best shown in  FIGS. 5, 6 , and  9 A can be employed if needed to more easily pass through the soft tissues of a subject. Other alternative embodiments, such as releasably securing the opposing bodies  44 ,  46  one to the other can include the use of at least one banding element  66 . The banding element, as best shown in  FIG. 8 , can be of an elastic nature and can remain in place after the user has employed the insertion tool  34  to force the spreading bearing  24  into the spreader bearing seat  56 . Alternatively, if employed, the banding element  66  can be composed of a material that fractures when the user applies force to the system to open the end plate  22  into a spread configuration or the banding element  66  can be composed of a material that initially stretches to permit movement of the opposing bodies  44 ,  46  away from each other and subsequently is adsorbed or dissolved naturally in the body of the subject. The modification of the system to include any such alternative still lies within the concept of the invention.  
         [0032]     The practice of the sequential steps of method of using the invention are well illustrated in FIGS.  10 A-V. The use of an alternative insertion cannula element having a guide wire scoop  68  is best illustrated in  FIGS. 10G and 101 . Advantageously, the lower portion of the insertion cannula  68  can be modified to include an open scoop-shaped portion that can serve to guide the blunt end  32  of the guide wire  24  into the lumen of the cannula. While the illustration shows the guide wire scoop  68  being useful in directing guide wire  12  back out of the body, it is within the scope of the invention to use such an alternative cannula with a scoop for guide wire insertion also.  
         [0033]     Another alternative embodiment, as best shown in  FIG. 5 , includes the use of an alternative guide wire  70  that is at least partially threaded. For use with such a guide wire, one or more, and preferably two releaseable locking elements  72 ,  74  can be employed at the outlying portions of the guidewire to hold the assembly of end plates  22  in relative position to each other. As shown in  FIG. 5 , an end plate spacer element  76  can be threaded along the guide wire as with other elements of the system and positioned between two end plates  22 A,  22 B. In such an alternative embodiment, the locking elements also serve to hold the spacer  76  securely between the two end plates  22 A,  22 B and the portion of the guide wire, which is threadably secured by the locking elements  72 ,  74  would remain in the subject after the procedure. It is also within the concept of the invention to also employ the spacer  76  between two end plates as demonstrated in  FIGS. 10S and 10U .  
         [0034]     Materials and manufacturing procedures as are well known in the art can be employed in the preparation of the invention.  
         [0035]     Each of the embodiments described above are provided for illustrative purposes only and it is within the concept of the invention to include modifications and varying configurations without departing from the scope of the invention that is limited only by the claims included herewith.