Abstract:
Embodiments of the present invention are directed to bone alignment rod connectors, and more particularly to traverse rod connectors. In one embodiment, the connector includes a housing having an opening configured to accommodate at least one rod, a setscrew assembly configured to secure the at least one rod when the at least one rod is placed in the opening. The setscrew assembly includes a setscrew and at least one circular/spherical object configured to interact with the setscrew when the setscrew is inserted in the housing. Upon insertion of the setscrew, the at least one spherical object is configured to laterally move towards the at least one rod to secure the at least one rod inside the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Application No. 60/725,031, to Laurence et al., filed Oct. 7, 2005, and titled “Transverse Rod Connector” and incorporates its entire disclosure herein by reference. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to the field of surgery, and more specifically, to connector devices for connecting and maintaining a spaced apart relationship between bone alignment rods (“transverse rod connectors”). 
         [0004]    2. Background of the Invention 
         [0005]    Anterior internal fixation of the thoracic and thoracolumbar spine is a growing trend in spinal surgery. In the thoracic and thoracolumbar spine, anterior fixation is indicated for burst fractures with significant canal compromise, vertebral body tumors requiring corpectomy and other indications requiring anterior stabilization. One of the advantages of anterior internal fixation includes an ability to provide complete canal clearance and decompression of bony fragments and/or total resection of a tumor. Additionally, anterior thoracic and thoracolumbar (ATL) surgery allows for fusion of a minimal number of motion segments, thus, allowing for more normal spine mechanics. 
         [0006]    Some conventional systems relate to a design of a rod-based system primarily for the management of thoracic, thoracolumbar, and lumbar burst fractures and tumors that permits anterior load sharing, allows for distraction to perform reduction and compression of the bone graft, is CT/MRI compatible, and easy to implant. Conventional systems can include vertebral body staples, plates, and anterior instruments used in conjunction with a variety of screws and rods to create a high-versatile anterior fixation system. 
         [0007]    Some conventional systems further include titanium construction that is compatible with current CT and MRI scanning technology, low profile implant systems, top-loading and top-tightening systems, and other parameters. Some systems also include cross-connectors that allow one-piece implant to be applied to a dual-rod construct for a top-loading approach. 
         [0008]    The conventional devices and systems have a number of disadvantages. These devices do not provide flexibility when adjusting the devices either prior to, during, or after their placement into the patient. Thus, these devices force a surgeon to utilize a specific configuration, leaving very little room for adjustment in accordance with patient&#39;s physiological characteristics and needs. Further, these devices do not allow a surgeon to connect multiple rods by actuating a single setscrew mechanism. 
         [0009]    Thus, there is a need for a fixation device that will provide flexibility to a surgeon or other qualified professional when installing and adjusting this fixation device to a particular patient as well as an ability to secure multiple rods of the device. 
       SUMMARY OF THE INVENTION 
       [0010]    Some of the embodiments of the present invention are directed to rod connectors, and more particularly to transverse rod connectors configured to secure multiple rods using, for example, a single setscrew. 
         [0011]    In one embodiment, the connector includes a bone alignment rod connector including a housing having an opening configured to accommodate at least one rod and a setscrew assembly having a setscrew and at least one circular object/member configured to interact with the setscrew when the setscrew is inserted in the housing. The setscrew assembly is configured to secure the at least one rod when the at least one rod is placed in the opening and upon insertion of the setscrew, the at least one circular object is configured to laterally move towards the at least one rod to secure the at least one rod inside the housing. 
         [0012]    In another embodiment, a method for securing a bone alignment rod within a receiving portion of a housing includes providing a housing having a receiving portion for receiving a bone alignment rod, a setscrew, and a top threaded opening configured to receive the setscrew and allow the setscrew to advance therein to establish a retaining force to retain the bone alignment rod within the receiving portion. The method also includes receiving the bone alignment rod within the receiving portion of the housing and advancing the setscrew into the threaded opening to establish the retaining force to retain the rod within the receiving portion. 
         [0013]    In yet another embodiment, a method for securing a spaced apart relationship between two bone alignment rods includes providing a housing having a pair of receiving portions in a spaced apart arrangement and each for receiving a respective bone alignment rod, a setscrew, and a top threaded opening configured to receive the setscrew and allow the setscrew to advance therein to establish a retaining force to retain each bone alignment rod with a respective receiving portion. The method also includes receiving a respective bone alignment rod within each receiving portion of the housing and advancing the setscrew into the threaded opening to establish the retaining force to retain each bone alignment rod in a respective receiving portion. 
         [0014]    Other embodiments of the present invention may be used to connect two rods (or more), preferably rigidly and preferably simultaneously, by actuating a single setscrew, and maintaining the rods in a spaced apart arrangement. Specifically, some embodiments of the invention include a main body having two slots (receiving portions), each sized appropriately to accommodate a rod in use and which are substantially parallel (for example). The main body may also include a hole having an axis which is substantially perpendicular to an axis of one or preferably both of the rod slots, and a third slot extending laterally on either side of the hole towards the two slots. 
         [0015]    The setscrew may have a conical surface (or other surface, e.g., spherical) on the interior portion to directly actuate the spheres against the rods. The setscrew may also indirectly actuate the spheres/circular members by using an insert with a relieved portion to accommodate the setscrew. The insert preferably includes an inclined surface at the sphere contact portion to facilitate actuation of the spheres. The forces that force a sphere outward may also tend to deform the insert against the setscrew. Thus, increased rotational force on the setscrew is transformed into a setscrew gripping action by the insert itself. This gripping action may prevent the setscrew from loosening during dynamic loading conditions (for example). 
         [0016]    The rod slots may be oversized to accommodate the capturing of rods which are initially skewed. Accordingly, in one embodiment of the invention, the action of tightening the setscrew captures the rods and persuades the rods into a substantially parallel configuration (for example)—this is accomplished by forcing the rods against a lateral surface of the rod slot. The openings of the lateral slot at the bilateral rod slots may be smaller than the space in which the spheres translate in order to prevent expulsion of the spheres from the interior body. 
         [0017]    Further features and advantages of the invention, as well as structure and operation of various embodiments of the invention, are further elaborated in detail below with references to the accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0018]    The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the figure number drawing in which the reference number first appears. 
           [0019]      FIG. 1  illustrates a perspective view of a lateral slot configuration according to one embodiment of the present invention (indirect actuation with lateral insert). 
           [0020]      FIG. 2  illustrates an exploded, perspective view of a lateral slot configuration according to one embodiment of the present invention (indirect actuation with lateral insert). 
           [0021]      FIG. 3  illustrates a side, cross-sectional view of the embodiment show in  FIGS. 1-2 , of the present invention. 
           [0022]      FIG. 4  illustrates a side, cross-sectional view of a lateral slot configuration according to another embodiment of the present invention (direct actuation without insert). 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    Some embodiments of the present invention relates to the field of surgery, and more specifically to a bone alignment rod (e.g. transverse rod) connector that may hold at least one and preferably two (or more) rods. The rod can be a cervical rod, a posterior rod, or any other rod used during medical applications. 
         [0024]      FIG. 1  illustrates a perspective view of the transverse rod connector  100 , having a housing  102  which includes a top portion  104 , a bottom portion  106 , a front portion  108 , a back portion  110 , and side portions  112 ,  114 . As illustrated, an x-y-z coordinate system can be used to better visualize the spatial orientation of elements in the housing  102 . Accordingly, the top and bottom portions  104 ,  106  are disposed in an x-z coordinate field, the side portions  112 ,  114  are disposed in the y-z coordinate field, and the front and back portions  108 ,  110  are disposed in the x-y coordinate field. 
         [0025]    The housing  102  further includes a central portion  116 , which, in the presently illustrated ( FIG. 1 ) embodiment, is disposed substantially in the middle of the housing  102 . The housing  102  further includes two open channels or openings  118 ,  120  disposed between the two side portions  112 ,  114  and the central portion  116 . The open channels  118 ,  120  may be formed by the top portion  104  and two side portions  112 ,  114  in the x-z coordinate field, and the central portion  116  in the y-z coordinate field. Thus, the open channel  118  is formed by the side portion  112 , central portion  116  and the top portion  104 . The open channel  120  is similarly formed by the side portion  114 , central portion  116  and the top portion  104 . The open channels  118 ,  120  may be open from the bottom portion  106  of the housing  102 . As can be understood by one skilled in the art, the housing  102  can include at least one such opening configured to accommodate placement of at least one rod. 
         [0026]    In the illustrated embodiment, the openings  108 ,  110  are configured to accommodate cylindrical rods, although, as can be understood by one skilled in the art, the openings  108 ,  110  can accommodate any shape rods, and may be formed to accommodate specially, custom shaped rods. 
         [0027]    The top portion  104  may further include an opening  122 , which may be elliptical, having a first, shorter diameter along the z-axis and a second, longer diameter along the x-axis. As can be understood by one skilled in the art, the opening  122  can have any other desired shape, such as circle, rectangle, square, polygon, or any other shape. 
         [0028]    As shown, the opening  122  may be made in the top of the central portion  116  of the housing  102 , and may be configured to accommodate insertion of spherical/circular objects/members  130   a  and  130   b  (not shown in  FIG. 1 ), a setscrew  132 , and an insert ( FIGS. 2-4 ). The opening  122  may extend downward in the x-y plane, although preferably, in one embodiment, the depth of opening  122  may be less than the height of the housing  102  (see  FIGS. 3-4 ). The opening  122  may further include threads  140  located longitudinally along the walls of the opening  122 . Threads  140  are preferably configured to accommodate corresponding threads provided on an exterior portion of the setscrew  132 , so that the setscrew  132  may be advanced into the opening  122 . 
         [0029]    The central portion  116  may further include openings  146   a  and  146   b  (not shown in  FIG. 1 ). The openings  146  are made in the side walls of the central portion  116  that separate channels  118 ,  120  and the opening  122 , respectively, and are preferably configured to allow spherical objects  130  to protrude into respective channels  118 ,  120 , when the objects  130  are placed inside the opening  122 . Once placed inside the opening  122 , the opening and preferably the insert, direct spherical objects  130  to the openings  146 , so that upon the objects  130  protruding out the openings, they interact with a respective rod. 
         [0030]      FIG. 2  is an exploded perspective view of the connector  100 . As shown in this embodiment, the setscrew  132  is configured to be placed inside an insert  210 . The insert  210  is used to preferably apply equal pressure, developed by advancement of the setscrew into the opening  122  (“retaining force”) to each of the spherical objects  130  when in contact with a respective rod. Accordingly, the combination of the spherical objects  130 , the insert  210 , and the setscrew  132  is then configured to correspond to the configuration of the opening  122 . 
         [0031]    In one embodiment, the spherical objects  130  are initially placed inside the opening  122 , where each is positioned adjacent a respective opening  146 , the insert  210  is placed on top of the spherical objects and, thereby, urges the spherical objects  130  closer to and/or out of the openings  146 . The openings  146  are preferably configured to prevent the spherical objects  130  from falling out into the channels  118 ,  120 , respectively. Once the insert  210  is placed inside the opening  122 , the setscrew  132  is threaded into the opening  122 . The threads  140  and corresponding threads  133  may be configured to allow clockwise or counter-clockwise advancement of the setscrew within opening  122 . Various means known in the art to lock the setscrew within the opening  122  after it has been threaded therein. Moreover, as can also be understood by one skilled in the art, the setscrew  132  can using any advancement means for applying a force to insert (and/or objects  130 ), other then the use of screw threads. 
         [0032]    In one embodiment, the insert  210  may have a trapezoidal shape, as shown in  FIGS. 2 and 3 , where the insert  210  may be further configured to have a length that is substantially equal to the larger diameter of the elliptical opening  122 . The insert  210  may also have a width that is substantially equal to the shorter diameter of the elliptical opening  122 . The insert  210  may also have a height that is substantially equal to the depth of the opening  122 . In this way, the insert  210  may tightly fit inside the opening  122  and may be fixed inside the opening  122 . The setscrew  132  along with the spherical objects  130  further prevents the insert  210  from becoming loose inside the opening  122 . 
         [0033]    As illustrated in  FIGS. 2-4 , the insert  210  may include a groove  214  sized to fit the setscrew  132 . The groove  214  may be configured to have a cubical or a parallelepipedal shape in order to accommodate the cylindrical nature of the setscrew  132 . As can be understood by one skilled in the art, the groove  214  can have any other shapes. The groove  214  is made in a longer base of the trapezoidal insert  210 , as shown in  FIG. 2 , and may also be configured not to interfere with threads  140  on the housing  102 . 
         [0034]    The insert  210  further includes diagonal sides  218  ( a, b ) that are configured to contact the spherical objects  130  ( a, b ), respectively, when the insert  210  is placed inside the opening  122  on top of the spherical objects  130 . In an embodiment, once the spherical objects  130 , the insert  210 , and the setscrew  132  are inserted into the opening  122 , by applying a downward rotational force (along the y-axis) to the setscrew  132  (when screwing-in the setscrew  132 ), the setscrew  132  pushes the insert  210  down (along the y-axis) and thereby the sides  218  are pushed toward the spherical objects  130  (along the x-axis). Thus, the spherical objects  130  are pushed out from the openings  146  (along the x-axis). 
         [0035]    Referring to  FIG. 3 , rods  302  and  304  are shown to be secured inside the channels  118 ,  120 , respectively. This may be accomplished by placing the rods  302 ,  304  inside the channels  118 ,  120 , placing a combination of the spherical objects  130 , the insert  210  and the setscrew  132  inside the opening  122 , and advancing the setscrew  132  along the threads  140 . Accordingly, this results in the insert  210  being pushed downwards and applies a translational force along the x-axis on the spherical objects  130 . Once, the spherical objects  130  are pushed out along the x-axis towards the rods  302  and  304 , the rods  302 ,  304  are pushed towards inner walls  306 ,  308 , respectively, of the housing  102 . As can be seen in the figure, preferably, the spherical objects interact with the rods such that they force the rods into the channel (e.g., upwards and outwards). Thus, this arrangement secures or holds the rods  302  and  304  inside the housing  102 . 
         [0036]      FIG. 4  illustrates an alternate embodiment of the housing  402 . In this embodiment, the housing  402  is substantially similar to the housing  102  of  FIG. 1 . However, instead of opening  102 , the housing  402  includes an opening  422  that may have a circular shape and uniformly extend downward inside the central portion  416  of the housing  402  forming a cylindrical channel. Furthermore, the insert  482  may have an inverted conical-shape bottom  474  and a cylindrical top  476 . The cylindrical top  476  may further include threads  470 . Threads  470  are configured to interact with threads  440  placed on the inner walls of the opening  422 . 
         [0037]    In this embodiment, the opening  422  may also include a groove  452  located towards the bottom portion  406  of the housing  402  (the portions and sides of the housing  402  are similar to the housing  102  of  FIG. 1 ). The groove  452  is configured to match the conical top  476  of the insert  482 . As such, when the spherical objects  430  are placed inside the opening  422  and the insert  482  is placed inside the opening  422  and is advanced along threads  440 , the sides of the conical bottom  474  contact the spherical objects  430  and push the spherical objects  430  along the x-axis, similar to the embodiment of  FIG. 1 . The groove  452  may be configured to receive the conical bottom  474  when the insert  482  is screwed-in along the threads  440 . 
         [0038]    In one embodiment, a setscrew  432  (similar to setscrew  132 ) can be threaded along the threads  440  inside the opening  422  to further secure the insert  482  and, thus, the rods  302  and  304 . As can be understood by one skilled in the art, the setscrew  432  (or setscrew  132 , if referring to  FIG. 1 ) can be advanced or removed using a tool having a head configured to interact with a recess (for example) in the head of the setscrew (e.g., screwdriver, a hexagonal wrench). 
         [0039]    As can be understood by one skilled in the art, the housing  102  can have any desired shape, such as cubical, parallelepipedal, spherical, elliptical, or any other shape. The housing  102  can also have rounded sides, portions and edges, as illustrated in  FIG. 1 . Additionally, the heights, widths, lengths of the side portion  112  or  114  can be same or different than the other and/or the height, width, length of the central portion  116 . 
         [0040]    As can be understood by one skilled in the art, the objects  130  can also have varying shapes and sizes, such as spheres, cubes, parallelepipeds, cylinders, or any other desired shapes. Further, the setscrew  132  can be any other locking device that is configured to secure the insert  210 , the objects  130  and the rods  302 ,  304  inside the housing  102 . 
         [0041]    Example embodiments of the methods and components of the present invention have been described herein. As noted elsewhere, these example embodiments have been described for illustrative purposes only, and are intended to be limiting, and thus, other embodiments are possible and are covered by the invention. Such embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.