Abstract:
A novel cross-connector assembly for interconnecting first and second bracing members or rods, one to the other. The cross-connector assembly is capable of multi-directional articulation in three dimensions, length, azimuth, and elevation and is also capable of having one end rotated along its longitudinal axis in relation to the other end so as to custom fit and securely connect the assembly to two opposing bracing members or rods. Also provided is a kit including the device and ancillary instrumentation to facilitate the method of the present invention.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a novel cross-connector assembly for interconnecting a first and a second bracing member or rod, which are in relative opposition to each other. More particularly the present invention relates to a novel multi-directional articulating cross-connector assembly configured to be simultaneously articulated in four directions including to be rotated in-part so as to custom fit to and securely connect two relatively parallel-aligned spinal rods, which are positioned along the longitudinal axis of a subject&#39;s spinal column. 
     2. Background of the Technology 
     Spinal fixation apparatuses are widely employed in surgical processes for correcting spinal injuries and diseases. These apparatuses commonly employ longitudinal link rods secured to coupling elements and are secured to the bone such as vertebrae by spinal bone fixation fasteners such as pedicle screws, hooks and others. The opposing pair of longitudinal link rods are commonly disposed along the longitudinal axis of the spine and are held in position relative to one another by cross-connectors, also known as transverse connectors or transverse bridge elements. 
     As the technology of spinal surgery has developed and improved, each of the necessary spinal fixation components has also undergone improvements and modifications to address the short-comings of conventional spinal appliances. While some improvements have been made in the design and operation of cross-connectors for spinal rods, there remains an unfulfilled need for a cross-connector that provides simplicity of operation with a minimal number of parts, which can provide reliable, secure attachment of two spinal rods that due to the natural and variable contours of the subject&#39;s spine are seldom in a perfectly parallel disposition, one to the other. 
     To meet the problem of securely connecting two opposing spinal rods together, a requirement exists to provide a cross-connector that can easily be manipulated during surgery in four directions to include being rotated in-part about the longitudinal axis of the connector; that is, a device is required that can rotate around each of the three axis of the device and also be translated to shorten or lengthen the device along its longitudinal axis before being securely locked into the desired position. In addition, the connector should be configured to provide a low profile with the smoothest possible contoured external surfaces to avoid irritation of adjacent soft tissue and thus promote healing and comfort for the subject post surgery. 
     Conventional efforts to meet this need have fallen short of the desired cross-connector configuration. For example, U.S. Pat. No. 6,554,832, issued to Shluzas, as best seen in FIGS. 2 and 4 of that patent, provides a transverse connector, which includes first and second connector members for connection to the respective first and second spine rods. The two connector members are connected one to the other by a connecting rod, which can be withdrawn or extended in alignment with the longitudinal axis of the cross-connector for purpose of adjusting the length thereof. As shown in FIG. 2 of the Shluzas patent, the extent of movement of the connecting rod (Shluzas at 42) inwardly through the opening (40) is limited by the design of the device, which after allowing a limited amount of inward movement of the connecting rod will impede further inward movement when the connecting rod (Shluzas at 42) comes into contact with the inwardly disposed portion of the connecting member (Shluzas at 30), the spine rod (Shluzas at 12), or possibly the set screw (Shluzas at 34). The design of the Shluzas connector thus provides a very limited inward adjustment of the length of the device. The device of Shluzas is also configured such that the connecting rod can be pivoted about a pivot axis to adjust the azimuth of the axis of the first connector in relation to the axis of the second connector. That is, the Shluzas device allows the surgeon to pivot the connecting rod about a pivot axis thus allowing one end of the multi-part transverse connector to be pivotally adjusted away from the longitudinal axis of the other end of the connector either caudally or cephallicly in relation to the subject&#39;s spinal column. Importantly the pivoting movement of the Shluzas connector is limited to movement within the same horizontal plane relative to the longitudinal axis of the spinal cord. Thus, while the device of Shluzas does permit some limited adjustment in length and azimuth of the device, it is configured to structurally prohibit any upward or downward movement in relation to the surface plane of the spinal column. That is, the elevation of one end of the Shluzas connector relative to the other end of the connector cannot be adjusted. While the connector of Shluzas does provide some improvement over earlier such devices, it still falls short of the need to provide a connector that can simultaneously be configured to be rotationally adjustable about each of the three axis and translated along the length of its longitudinal axis. That is, the device of Shluzas cannot be adjusted in all three planes: length, azimuth, and elevation as well as be rotated in-part around the connector&#39;s longitudinal axis. 
     Thus a need exists for a cross-connector assembly that provides ease of operation by the surgeon to adjust one connecting end of the assembly in relation to the other end of the assembly by rotation of the device around each of the three axis and translated in length along the longitudinal axis, to securely lock the assembly in the selected configuration, and to provide a cross-connector that has a low profile and the smoothest possible external surface contours to promote healing and minimal irritation of adjacent soft tissues in the subject. 
     SUMMARY OF THE INVENTION 
     The cross-connector assembly and method of application of the present invention provides a novel multi-directional articulating cross-connector assembly configured to be capable of being simultaneously articulated in the three dimensions of length, azimuth, and elevation and to be rotated about its longitudinal axis so as to custom fit to and securely connect two opposing rods or bracing members, which are positioned in opposition to each other along the bone portions being secured by the assembly. 
     Also provided is a novel articulation member as part of an articulating and locking component of the multi-directional cross-connector assembly, that articulation member enabling multi-directional manipulation of the assembly and also providing a secure locking function to maintain the assembly in the selected configuration. 
     Also provided is a novel cross-connector assembly, which can be securely locked into a selected position relative to the two opposing rods or bracing members, the locking members being configured to provide a low profile and a smooth external surface contour to avoid irritation of adjacent soft tissue and thus promote healing. 
     Also provided is a kit that can include at least one of the novel cross-connection assemblies of the present invention, a set of securing members or screws adapted for attaching spinal rods to the bone of a subject, a set of spinal rods, and surgical instruments configured to be capable of facilitating the insertion of the cross-connector assembly into a subject and the fixation of the device to the spinal rods. 
     Also provided is a method of using the novel cross-connector assembly of the present invention such that the surgical procedure employed, in comparison to conventional methods, is quickly accomplished with low risk to the subject to which the assembly is being surgically attached. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  shows a frontal view of the cross-connector assembly of the present invention with a representative spinal rod in a secured position in each of the spinal rod connector members, 
         FIG. 2  shows a cross-sectional frontal view (Section A-A) of the cross-connector assembly shown in  FIG. 1 ; 
         FIG. 3  shows a top view of the cross-connector assembly of the present invention and the section line (A-A) of the cross-sectional frontal view (Section A-A) of  FIG. 2 ; 
         FIGS. 4A ,  4 B,  4 C and  4 D respectively show perspective views of the capacity to vary rotation in-part, vary azimuth, vary elevation, and vary length of the cross connector assembly of the present invention; 
         FIG. 5  shows a detail cross-sectional view of the joint assembly portion viewed along the transverse axis of the cross-connector assembly of the present invention; 
         FIG. 6  shows a detail cross-sectional view of the joint assembly portion viewed along the longitudinal axis of the cross-connector assembly of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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 are non-limiting, but serve merely as a basis for the invention defined by the claims provided herewith. 
     A novel cross-connector assembly  10  constructed in accordance with the present invention is illustrated in  FIGS. 1-6 . The cross-connector assembly  10  of the present invention is configured to fit to and securely connect two opposing bracing members or spinal rods, one at a first end  12  and the other at a second end  14  of the cross-connector assembly  10 . The general configuration of a cross-connector assembly or transverse connector attached to a pair of spinal rods, which are in relative parallel-alignment with the spinal column of a subject is well illustrated by conventional devices such as shown in U.S. Pat. No. 6,554,832, issued to Shluzas U.S. Pat. No. 5,980,523, issued to Jackson, and U.S. Pat. No. 6,096,039 issued to Stoltenberg et al., the disclosures of which are each fully incorporated herein by reference. The cross-connector assembly  10  of the present invention similar to the devices disclosed in the immediately above incorporated references is configured for and capable of connection to a pair of spinal rods, which are secured in relative parallel alignment with the spinal column of a subject. However, due to the novel construction of the cross-connector assembly  10  of the present invention, the surgeon is now able to use a cross-connector that, as best shown in  FIGS. 4A-4C  can rotated about all three axes and translated about its longitudinal axis to shorten or length the device ( FIG. 4D ). The novel design of the present invention and its capability to be so easily configured and adjusted to securely fit the needs of individual subjects has never before been made available in the art of spinal surgery. 
     As best shown in  FIGS. 1-3 , the cross-connector assembly  10  is an elongated assembly having a first end  12  and a second end  14 . A first connector, such as spinal rod connector  16  extends from the first end  12  of the cross-connector assembly  10  to a terminal end  18  of an arm, such as cylindrical arm  20 . The first spinal rod connector  16 , at the first end  12  of the cross-connector assembly  10  defines a first securing member, such as spinal rod clasping member  22 . The first spinal rod clasping member  22  can have any shape that is suitable for attachment to a bracing member or rod but is preferably configured with a hook shaped design that is sized and configured to approximate the shape of the rounded contour of a first spinal rod, a representation of a transverse section of a first spinal rod is shown at  24 . 
     A second connector, such as spinal rod connector  26 , extends from the second end  14  of the cross connector assembly  10  toward the first end  12  of the cross-connector assembly  10  and terminates at an articulation assembly housing  28 . The articulation assembly housing  28  defines an arm receiving portal  30 , which is sized and configured to slidably and rotatably receive the arm  20  of the first spinal rod connector  16 . The second spinal rod connector  26 , at the second end  14  of the cross-connector assembly  10  defines a second spinal rod clasping member  32 . The second spinal rod clasping member  32  can be configured with a hook shaped design that is sized and configured to approximate the shape of the rounded contour of a second spinal rod, a representation of a transverse section of a second spinal rod is shown at  34 . 
     The first spinal rod  24  and the second spinal rod  34 , when respectively positioned within the first clasping member  22  and the second clasping member  32 , can be securely held in a releasably locked position by corresponding first and second clasping member set screws  36 ,  38 . The first and second clasping member set screws  36 ,  38  are sized and configured to threadably attach to the respective first and second spinal clasping members  22  and  32  through respective first and second set screw receiving portals  40 .  42 , which are defined by the first and second clasping members  22 ,  32  respectively. The first and second set screw receiving portals  40 ,  42  are sized and configured to permit the respective first and second set screws  36 ,  38  to be threaded into and through the respective clasping members  22 ,  32  such that the set screws  36 ,  38  can make secure, locking contact with a respective first and a second spinal rod  24 ,  34 , when such rods are properly positioned. The length of the first and second set screws  36 ,  38  can be such that when in the locked position and securely holding their respective spinal rods  24 ,  34  in place within the respective clasping member  22 ,  32 , the respective heads  44 ,  46  of each of the first and second set screws  36 ,  38  will be approximately flush with or below the upper surface level of the respective first and second clasping members  22 ,  32 . Thus, when a spinal rod  24 ,  34  is securely locked in place in the first and/or second clasping member  22 ,  32  the first and second set screws  36 ,  38  will not extend above the smooth contour of the upper surface of the first and second clasping members  22 ,  32  and therefore provide a low profile cross-connection assembly that is less obtrusive and irritating to adjacent tissue than is typical for many conventionally implanted devices. 
     The first spinal rod connector  16  and the second spinal rod connector  26  are adjustably connected one to the other by the passage of the cylindrical arm  20  of the first spinal rod connector  16  passing through the cylindrical arm receiving portal  30  of the articulation assembly housing  28  of the second connector  26 . The articulation assembly housing  28  defines the cylindrical arm receiving portal  30  as a passage extending through the housing  28  along the longitudinal axis of the cross-connector assembly  10 . The articulation assembly housing  28  also defines a threaded articulation assembly set screw portal  48 , which extends downward toward the axis of the cylindrical arm receiving portal from the upper exterior of the articulation assembly housing  28  to a point extending below the cavity formed by the cylindrical arm receiving portal  30 . Thus, the cylindrical arm receiving portal  30  and the articulation assembly set screw portal  48  jointly form a hollow interior space within the assembly housing  28 , wherein the crossing of the respective axis of each of the two joining portals  30 ,  48  roughly resembles an inverted “T” shape. As best shown in  FIGS. 2 ,  5 , and  6 , a novel split-ball articulation member  50  is sized and configured to be rotatably positioned within an articulation cavity  52 , which is formed within the articulation housing  28  by the common space defined by the intersection cylindrical arm receiving portal  30  and the articulation assembly set screw portal  48 . 
     As best shown in  FIGS. 5 and 6 , the size and configuration of the split ball articulation member  50  is such that the split ball defines a split ball interior passage  54  having a passage entrance  57  and passage exit  58  through which the cylindrical arm  20  can slidably pass along the longitudinal axis of the cross-connector assembly  10 . As best shown in  FIGS. 2 ,  5 , and  6 , the interior passage  52  of the split ball articulation member  50  includes a split ball guide pin  60  which protrudes into the interior passage  52  from the inner wall of the split ball interior passage  54 . The split ball guide pin  60  is sized and configured to easily ride in a cylindrical arm guide pin slot  62 , which is defined in the surface of the cylindrical arm  20 . 
     Factors of growth, effects of age, injury, disease, and other influences can typically cause less than perfect symmetry in the spinal column of a subject. As a result, surgical devices and appliances such as the cross-connector assembly  10  of the present invention will be poorly fit to the spinal column of a subject unless the devices are capable of being easily and securely reconfigured for a more customized fit to the subject. The present invention provides a novel cross connector assembly that can be reconfigured by a surgeon to change the length of the assembly  10 , the rotational alignment of the first and second ends  12 ,  14  to each other, the sideward alignment or azimuth relationship of the first and second ends  12 ,  14  to each other, and the elevation relationship of the first and second ends  12 ,  14  to each other. Each of these re-configurations, as shown in  FIGS. 4A-4D , are made possible by the novel articulation assembly generally shown at  68  in  FIGS. 5 and 6 . 
     The articulation assembly  68 , which includes the articulation assembly housing  28 , the split ball articulation member  50 , and the cylindrical arm  20  of the first spinal rod connector  16 , makes it possible for a user to make each of the cross-connector assembly  10  re-configurations mentioned above. 
     As shown in  FIG. 4D , the length of the cross-connector assembly  10  can be adjusted by movement along the longitudinal axis of the assembly  10  of the first spinal rod connector  16  in relation to the second spinal rod connector  26 . During such adjustment of the length of the cross-connector assembly  10 , the split ball guide pin  60  of the split ball articulation member  50  is held in position by the articulation assembly housing  28  while the first spinal rod connector  16  with its cylindrical arm  20  and integral cylindrical arm guide pin slot  62  are adjusted inwardly or outwardly along the longitudinal axis of the cross-connector assembly  10 . When such relative movement of the first and second spinal rod connectors  16 ,  26  is made, the interaction of the guide pin  60  as it slides along the length of the guide pin slot  62  serves to control the extent of such movement. As best shown in  FIGS. 2 and 6 , the cylindrical arm guide pin slot  62  has a distal stop  64  and a proximal stop  66  ( FIGS. 2 ,  4 A-B, and  6 ), which serve the purpose of limiting the movement of the guide pin  60  only to positions in the guide pin slot  62  that are between the distal and proximal stops  64 ,  66 . 
     The split ball articulation member  50  can be rotated within the articulation assembly housing  28  so as to change the rotational relationship of the first and second spinal rod connectors  16 ,  26  in relation to each other. Such rotation of the split ball articulation member  50  allows the user to simultaneously reconfigure the cross-connector assembly  10  in more than one plane or dimension, such that the rotational alignment ( FIG. 4A ), the azimuth alignment ( FIG. 4B ), and the elevation alignment ( FIG. 4C ) of the cross-connector assembly  10  can be quickly and easily adjusted. 
     The cross-connector assembly  10 , after being reconfigured by the user to provide a best fit to the subject to which the device is to be applied, can be quickly and securely but releasably locked into the selected configuration. As shown in  FIGS. 2 ,  3 ,  4 A- 4 B,  5 , and  6 , an articulation set screw  70  is configured to threadably engage the articulation assembly set screw portal  48  so as to bring pressure against the split ball articulation member  50  when screwed into the articulation assembly housing  28  in a locked position. When in a locked position, as best shown in  FIGS. 5 and 6 , the articulation set screw  70  contacts the split ball articulation member  50  at whatever rotational position it may be in and holds it fast within the articulation cavity  52 . By locking the split ball  50  into a specific position within the articulation cavity  52 , further movement of cross-assembly connector components to alter the configuration of rotation, azimuth, or elevation are made impossible. A split ball slit  72  is defined by and along a portion of the circumference of the split ball articulation member  50 . The split ball slit  72  is of a size, depth, and length along a portion of the circumference of the split ball articulation member  50  to as to allow flexible and reversible deformation and compression inward of the split ball articulation member  50  when sufficient force is applied by the inward movement of the articulation set screw  70  against the split ball articulation member  50 . Upon compression of the split ball actuation member  50  by the articulation set screw, the split ball slit  72  narrows and allows the adjacent portions of the split ball articulation member to make locking contact against the surface of the cylindrical arm  20 . Such locking contact serves to stop further slidable movement of the cylindrical arm  20  through the split ball interior passage  54  and the cylindrical arm receiving portal  30 . 
     Locking of the articulation assembly  68  so as to stop unwanted further reconfiguration of the cross-connector assembly  10  can be done simultaneously for all axis of movement of the assembly by forcefully and fully tightening the articulation set screw  70  into a locked position within the articulation assembly housing. Alternatively, by threadably adjusting the articulation set screw  70  into the articulation assembly set screw portal  48  only to a position that results in locking contact with the split ball  50  and stops further rotation of the split ball  50  within the articulation cavity  52  can still allow slidable movement of the cylindrical arm  20  through the split ball interior passage  54 . In this alternative two-step locking process, after the length of the cross-connector  10  is adjusted by movement of the cylindrical arm  20 , an additional application of force by the articulation set screw  70  can result in compression of the split ball  50  to stop further movement of the cylindrical arm  20 . 
     It is within the concept of the present invention that the articulation assembly  68  can be configured such that the mechanism permits the location of the articulation set screw  70  to be in alignment with the transverse axis of the connector assembly  10 , that is to be located on the side of the articulation assembly housing  28 . 
     Thus, the present invention provides a novel cross-connector assembly that can be simultaneously, securely, and releasably reconfigured to adjust the length, azimuth, elevation, and rotation of the components of the device relative to each other. 
     The materials used to construct the present invention are those which have sufficient strength, resiliency, and biocompatability as is well known in the art for such devices. Methods of manufacture of such surgical implant devices is also well known in the art. 
     It is within the concept of the present invention to provide the cross-connector assembly  10  as part of a kit for use in a surgical process, the kit comprising at least the cross-connector assembly and at least some of the associated tools for using said cross-connector assembly. In addition, the kit can contain spinal rods and associated screws or connectors for connecting the rods to the bone of a subject. 
     Each of the embodiments described above are provided for illustrative purposes only and it is within the concept of the present invention to include modifications and varying configurations without departing from the scope of the invention that is limited only by the claims included herewith.