Abstract:
There is disclosed at least one adjustable cross connector comprising two curved members which couple to each other in a slideable fashion, wherein the free ends are adapted to couple with a rod or another member of a spine stabilization system.

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
       [0001]    The present application is related to and claims priority from the following commonly assigned patent applications: U.S. Provisional Patent Application 60/775,879, entitled “Aligning Cross-Connector,” filed on Feb. 23, 2006; and U.S. Provisional Patent Application 60/814,943, entitled “Aligning Cross-Connector,” filed on Jun. 19, 2006. The disclosures of which are hereby incorporated by reference. 
         [0002]    The present application is related to the following commonly assigned patent applications: U.S. patent application Ser. No. 10/914,751, entitled “System and Method for Dynamic Skeletal Stabilization,” filed on Aug. 9, 2004; U.S. Provisional Patent Application 60775877, entitled “Multi-Level Spherical Linkage Implant System,” filed on Feb. 23, 2006; U.S. patent application Ser. No. 11/443,236, entitled “System and Method for Dynamic Skeletal Stabilization,” filed on May 30, 2006; U.S. Provisional Patent Application 60814753, entitled “Multi-Level Spherical Linkage Implant System,” filed on Jun. 19, 2006; U.S. patent application Ser. No. 11/467,798, entitled “Alignment Instrument for Dynamic Spinal Stabilization Systems,” filed on Aug. 28, 2006; U.S. Provisional Patent Application 60826763, entitled “Alignment Instrument for Dynamic Spinal Stabilization Systems,” filed on Sep. 25, 2006; U.S. Provisional Patent Application 60863284, entitled “Alignment Instrument for Dynamic Spinal Stabilization Systems,” filed on Oct. 27, 2006; and U.S. patent application Ser. No. ______, entitled “MULTI-LEVEL SPHERICAL LINKAGE IMPLANT SYSTEM” filed on Feb. 23, 2007; the disclosures of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0003]    This disclosure relates to skeletal stabilization and, more particularly, to systems and methods for dynamic stabilization of human spines. 
       BACKGROUND 
       [0004]    The human spine is a complex structure designed to achieve a myriad of tasks, many of them of a complex kinematic nature. The spinal vertebrae allow the spine to flex in three axes of movement relative to the portion of the spine in motion. These axes include the horizontal (bending either forward/anterior or aft/posterior), roll (bending to either left or right side) and vertical (twisting of the shoulders relative to the pelvis). 
         [0005]    In flexing about the horizontal axis, into flexion (bending forward or anterior) and extension (bending backward or posterior), vertebrae of the spine rotate about the horizontal axis to various degrees of rotation. The sum of all such movement about the horizontal axis of produces the overall flexion or extension of the spine. For example, each of the vertebra that make up the lumbar region of the human spine move through roughly an arc of 15° relative to its adjacent or neighboring vertebrae. Vertebrae of other regions of the human spine (e.g., the thoracic and cervical regions) have different ranges of movement. Thus, if one were to view the posterior edge of a healthy vertebrae, one would observe that the edge moves through an arc of some degree (e.g., of about 15° in flexion and about 5° in extension if in the lumbar region) centered around an elliptical center of rotation. During such rotation, the anterior (front) edges of neighboring vertebrae move closer together, while the posterior edges move farther apart, compressing the anterior of the spine. Similarly, during extension, the posterior edges of neighboring vertebrae move closer together, while the anterior edges move farther apart, compressing the posterior of the spine. Also during flexion and extension, the vertebrae move in horizontal relationship to each other, providing up to 2-3 mm of translation. 
         [0006]    In a normal spine, the vertebrae also permit right and left lateral bending. Accordingly, right lateral bending indicates the ability of the spine to bend over to the right by compressing the right portions of the spine and reducing the spacing between the right edges of associated vertebrae. Similarly, left lateral bending indicates the ability of the spine to bend over to the left by compressing the left portions of the spine and reducing the spacing between the left edges of associated vertebrae. The side of the spine opposite the compressed portion is expanded, increasing the spacing between the edges of vertebrae comprising that portion of the spine. For example, the vertebrae that make up the lumbar region of the human spine rotate about an axis of roll, moving through roughly an arc of 10° relative to its neighbor vertebrae, throughout right and left lateral bending. 
         [0007]    Rotational movement about a vertical axis relative to the portion of the spine moving is also desirable. For example, rotational movement can be described as the clockwise or counter-clockwise twisting rotation of the vertebrae during a golf swing. 
         [0008]    The inter-vertebral spacing (between neighboring vertebrae) in a healthy spine is maintained by a compressible and somewhat elastic disc. The disc serves to allow the spine to move about the various axes of rotation and through the various arcs and movements for normal mobility. The elasticity of the disc maintains spacing between the vertebrae, allowing room or clearance for compression of neighboring vertebrae, during flexion and lateral bending of the spine. In addition, the disc allows relative rotation about the vertical axis of neighboring vertebrae, allowing twisting of the shoulders relative to the hips and pelvis. Clearance between neighboring vertebrae maintained by a healthy disc is also important to allow nerves from the spinal chord to extend out of the spine, between neighboring vertebrae, without being squeezed or impinged by the vertebrae. 
         [0009]    In situations (based upon injury or otherwise) where a disc is not functioning properly, the inter-vertebral disc tends to compress, and in doing so pressure is exerted on nerves extending from the spinal cord by this reduced inter-vertebral spacing. Various other types of nerve problems may be experienced in the spine, such as exiting nerve root compression in the neural foramen, passing nerve root compression, and ennervated annulus (where nerves grow into a cracked/compromised annulus, causing pain every time the disc/annulus is compressed), as examples. Many medical procedures have been devised to alleviate such nerve compression and the pain that results from nerve pressure. Many of these procedures revolve around attempts to prevent the vertebrae from moving too close to each other thereby maintaining space for the nerves to exit without being impinged upon by movements of the spine. 
         [0010]    In one such procedure, screws are embedded in adjacent vertebrae pedicles and rigid rods or plates are then secured between the screws. In addition other devices, such as a fusion cage or spacer, may be inserted in-between the adjacent vertebrae to aid in fusing the vertebrae together. In such a situation, the pedicle screws (which are in effect extensions of the vertebrae) and rods serve to distract the degenerated disc space, maintaining adequate separation between the neighboring vertebrae, so as to prevent the vertebrae from compressing the nerves. This prevents nerve pressure due to extension of the spine; however, when the patient then tries to bend forward (putting the spine in flexion), the posterior portions of at least two vertebrae are effectively held together. Furthermore, the lateral bending or rotational movement between the affected vertebrae is significantly reduced, due to the rigid connection of the spacers. Overall movement of the spine is reduced as more vertebras are distracted by such rigid spacers. This type of spacer not only limits the patient&#39;s movements, but also places additional stress on other portions of the spine (typically, the stress placed on adjacent vertebrae without spacers being the worse), often leading to further complications at a later date. 
         [0011]    In other procedures, dynamic fixation devices may be used to preserve some motion of the spine while still distracting the vertebrae to relieve pressure placed on the various nerves. However, dynamic fixation devices may require additional stability. Furthermore, some systems might require alignment during implantation. 
         [0012]    What is needed is additional stability for use in dynamic or fusion systems while increasing the ease of insertion by allowing for alignment and adjustability of components during implantation. 
       SUMMARY 
       [0013]    In response to these and other problems, there is presented certain aspects which may provide methods and systems for providing additional stability to spine stabilization. For instance, there is disclosed at least one adjustable cross connector comprising two curved members which couple to each other in a slideable fashion, wherein the free ends of the adjustable cross connector are adapted to couple with a rod or another member of a spine stabilization system. 
         [0014]    These and other features, and advantages, will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. It is important to note the drawings are not intended to represent the only aspect of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following Detailed Description taken in conjunction with the accompanying drawings, in which: 
           [0016]      FIG. 1  is a perspective view of one possible embodiment of a system incorporating a cross-connector and a pair of dynamic stabilization systems; 
           [0017]      FIG. 2A  is an enlarged perspective view of one possible embodiment of a cross-connector which may be used in conjunction with a dynamic stabilization system; 
           [0018]      FIG. 2B  is a perspective view of one possible embodiment of a first elongated member of the cross-connector shown in  FIG. 2A . 
           [0019]      FIG. 2C  is top view of the cross-connector illustrated in  FIG. 1 ; 
           [0020]      FIG. 3  is a perspective view of one possible embodiment of an alignment device attached to a cross-connector and dynamic stabilization system; 
           [0021]      FIG. 4A  is a perspective view of one possible embodiment of an adapter which may be used with a cross-connector and an alignment rod; 
           [0022]      FIG. 4B  is a perspective view of an alternative embodiment of an adapter which may be used with a cross-connector and an alignment rod; 
           [0023]      FIG. 5A  is a an exploded view of an alternative embodiment of a cross-connector; 
           [0024]      FIG. 5B  is a top view of the cross-connector illustrated in  FIG. 5A . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    For the purposes of promoting an understanding of the principles of the present inventions, reference will now be made to the embodiments, or examples, illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the inventions as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0026]    In some embodiments, a cross-connector is disclosed that may be utilized for both aligning and providing additional stability to one or more dynamic stabilization constructs. A dynamic stabilization construct may be placed on each side of the spinous process of the spine. The cross connector may then secure the two or more dynamic stabilization constructs together to provide additional stabilization. The cross-connector may be designed to attach to a dynamic stabilization construct(s) and thereafter be adjusted as to align with the spine&#39;s natural center of rotation or other location as desired by a surgeon. Once the cross connector is aligned, it may be secured together and may remain in place as part of the stabilization system. The cross connector and dynamic stabilization construct together may provide additional stability to the spine and may aid in permitting a substantial range of motion in flexion, extension, rotation, anterior-posterior translation and/or other desired types of spinal motion. The cross connector device disclosed below may be used with any dynamic of fusion system. 
         [0027]    Referring to  FIG. 1 , one embodiment of a system is shown that may incorporate a cross connector  60  secured between two spine stabilization constructs  10  and  110 . Similar spine stabilization constructs are disclosed in further detail pending patent application Ser. No. ______, entitled “MULTI-LEVEL SPHERICAL LINKAGE IMPLANT SYSTEM” filed on Feb. 23, 2007 and in pending U.S. patent application Ser. No. 60/775,877 entitled “MULTI-LEVEL SPHERICAL LINKAGE IMPLANT SYSTEM,” filed Feb. 23, 2006, the contents of which are incorporated herein by reference. 
         [0028]    For purposes of illustration, only the spine stabilization construct  10  will be described in detail. The spine stabilization construct  110  contain similar components and will not be described in detail. Furthermore, for purposes of clarity, only a portion of the spine stabilization constructs  10  and  110  are illustrated in  FIG. 1 . 
         [0029]    In certain embodiments, the spine stabilization construct  10  may incorporate a plurality of bone anchors  12 A,  12 B and  12 C (bone anchor  12 C is not shown for purposes of clarity). The bone anchors  12 A- 12 C each have a distal end which secures to a patient&#39;s vertebrae. In certain embodiments, the proximal end of the bone anchors  12 A- 12 C may secure directly or indirectly to one or more rods  14 A- 14 C in a polyaxial manner (the connection between bone anchor  12 C and rod  14 A is not shown in  FIG. 1  for purposes of clarity). As illustrated, the rods  14 B and  14 C may couple to cylindrical heads  26 A- 26 B which may be multi-axially coupled to the bone anchors  12 A- 12 B (respectively). In certain embodiments, the cylindrical heads  26 A- 26 B may have an aperture that is dimensioned to receive one or more rods  14 B- 14 C. The rods  14 B- 14 C may be able to slide within the aperture of cylindrical heads  26 A- 26 B and move along multiple axis relative to the bone anchors  12 A- 12 B to allow for proper alignment and easy installation. 
         [0030]    In certain embodiments, one or more dynamic braces  16 A- 16 B may be located between two or more bone anchors  12 A- 12 B. The dynamic braces  16 A- 16 B may be coupled to respective rods  14 A- 14 C which may couple to bone anchors  12 A- 12 C. In certain embodiments, the dynamic braces  16 A- 16 B may be offset from a longitudinal axis extending between two adjacent bone anchors. The offset may provide additional spacing for the dynamic braces  16 A- 16 B so that the dynamic braces  16 A- 16 B do not interfere with the neighboring anatomy of the spine. The offset of the dynamic braces  16 A- 16 B may be positioned towards either side of the longitudinal axis of two adjacent bone anchors. 
         [0031]    Dynamic braces  16 A- 16 B may be coupled directly to respective rods  14 A- 14 C or connecting members  18 A- 18 D may be used to couple the rods  14 A- 14 C to dynamic braces  16 A- 16 B (respectively). The connecting members  18 A- 18 D may enable the braces  16 A- 16 B to be adjusted axially along the rods  14 A- 14 C. The connecting members  18 A- 18 D may also allow for rotational movement with respect to the rods  14 A- 14 C. The connecting members  18 A- 18 D thus may allow for increased adjustability of dynamic braces  16 A- 16 B and rods  14 A- 14 C. This adjustability may allow the surgeon to align and place various components of dynamic stabilization construct  10  (and  110 ) more easily. Once the desired axial position and angulation of the braces  16 A-B are achieved the rods  14 A- 14 C and the cylindrical heads  26 A- 26 B may be fastened securely to bone anchors  12 A- 12 B by a locking elements  28 A- 28 B. Locking elements  28 A- 28 B may be threaded locking caps or collets, or other suitable locking elements known to those skilled in the art. After dynamic stabilization construct  10  is implanted on one side of the spinous process, the procedure detailed above may be repeated on the opposing side of the spinous process for dynamic stabilization construct  110 . 
         [0032]    In certain embodiments, after two or more opposing dynamic stabilization constructs  10  and  110  are secured to the spine, a cross-connector  60  may be used to further stabilize the opposing dynamic stabilization constructs  10  and  110 . The cross connector  60  may attach to the constructs  10  and  110  such that the cross connector  60  does not interfere the motion of dynamic braces  16 A- 16 B. For example,  FIG. 1  shows the cross connector  60  attached to two opposing rods  14 C and  14 D. The dynamic braces  16 A and  16 B may thus be partially stabilized by cross connector  60 , while not hindering the natural controlled motion of dynamic braces  16 A and  16 B. 
         [0033]    Referring now to  FIGS. 2A-2C , one embodiment of the cross-connector  60  of  FIG. 1  is illustrated in greater detail. The opposing rods  14 C and  14 D may have gripping features  62 A and  62 B which may aid in securing the rods  14 C and  14 D to cross connector  60 , as shown in  FIG. 2A . These gripping features  62 A and  62 B may include not only indentations as shown in  FIG. 2A , but may also include a section of the rod having a different cross sectional geometries, such as rectangular, hexagonal, octagonal or hemi circular. Protrusions and indentations of various shapes and geometries may be located on the rod to aid in the attachment of the cross-connector  60  to the rods  14 C and  14 D. The rods  14 C and  14 D may also have a rough surface texture to aid in rigidly securing the cross connector  60  to the rods  14 C and  14 D. 
         [0034]    In certain embodiments, the cross-connector  60  may incorporate two or more elongated members  64  and  66 . The first and second elongated members  64  and  66  may have a rod gripping portion  102  and  104  at their exterior ends. In certain embodiments, the rod gripping portion  102  and  104  of the first and second elongated members  64  and  66  may secure to the rods  14 C and  14 D (respectively) by a snap-fitting around the gripping features  62 A and  62 B. As illustrated in  FIG. 2C , the rod gripping portions  102  and  104  may have a hook shape which may interface with gripping features  62 A and  62 B to aid in capturing rod  14 C and  14 D. In certain embodiments, the rods  14 C and  14 D may be further secured to elongated members  64  and  66  by inserting a threaded fastener (not shown), such as a set screw, through elongated members  64  and  66  such that the set screw presses against rods  14 C and  14 D respectively. 
         [0035]      FIG. 2B  is a detailed view of one embodiment of the first elongated member  64 . In some embodiments, the first elongated member  64  may have a curved elongated portion  65 . 
         [0036]    In certain embodiments an elongated recess or groove  67  may extend partially into the top surface of the first elongated member. The elongated recess or groove  67  may extend longitudinally along the first elongated member  64  to allow for an almost infinite number of adjustable positions for the first and second elongated members. Similarly, the second elongated member  66  may have also have an elongated curved portion and an elongated recess  68  ( FIG. 2A ) that extends into the top surface of the second elongated member  66 . The elongated recess  68  may extend longitudinally along the second elongated member  66  to allow for adjustability of the longitudinal position of the first and second elongated members  64  and  66 . In certain embodiments, the elongated recess  68  may receive a fastener  70  to lock the first and second elongated members  64  and  66  together. The fastener  70  may have a distal threaded section and a proximal head section. The elongated recess  68  may be dimensioned so that the proximal head section of fastener  70  is flush or below the top surface of second elongated member  66  to prevent fastener  70  from interfering with neighboring anatomy of the patient&#39;s spine. An elongated slot  71  may be located within recess  68  which extends through the bottom surface of second elongated member  66 . The threaded section of fastener  70  may pass through elongated slot and into groove  67  on the first elongated member  64 . In other embodiments threaded section of fastener  70  may lock onto the top surface of first elongated member  64 . 
         [0037]    In certain embodiments the elongated portion of the first elongated member  64  may be temporarily pivotably and slidingly mated to the elongated portion of the second elongated member  66 . The adjustability of first and second elongated members  64  and  66  may allow cross connector  60  to accommodate the spine anatomy of patients of all sizes and bone structures. The first member  64  and second member  66  may telescope or slide across each other (as shown in  FIG. 2C ) enabling adjustment of the rods  14 C and  14 D for alignment of the spine stabilization system  10  and  110 . The radius of curvature of the top section of the first member  64  may be substantially the same as the radius of curvature of the bottom section of the second elongated member  66  which may aid in the smooth controlled pivoting and sliding of the two elongated members  64  and  66  relative to each other. Once the desired angle and longitudinal position of the two elongated members  64  and  66  are achieved the fastener  70  may be inserted into the recess  68  and such that fastener  70  extends through the elongated slot  68  on the second elongated member and contacts the top surface or the groove  67  of the first elongated member to lock the two elongated members  64  and  66  together. 
         [0038]    In certain embodiments, cross connector  60  may be preassembled with the bottom surface of the second elongated member  66  mated to the top section of the first elongated member  64 . The fastener  70  may be partially inserted into the recess  68  and hand tightened such that a small compressive force acts on the top surface (or the groove  67 ) of the first elongated member  64  so that first and second elongated members  64  and  66  may still slide and pivot relative to each other. Once the desired position of cross connector  60  is achieved during implantation, the fastener  70  may be tightened with an instrument to rigidly and permanently secure the first and second elongated members  64  and  66  together. 
         [0039]    Referring now to  FIG. 3 , one possible embodiment of the cross-connector  60  is illustrated connected to the spine stabilization constructs  10  and  110  and aligned with a center of rotation, which is illustrated as point A. As explained in detail in U.S. patent application Ser. Mo. 11/467,798, entitled “Alignment Instrument for Dynamic Spinal Stabilization Systems,” filed on Aug. 28, 2006; U.S. Provisional Patent Application 60826763, entitled “Alignment Instrument for Dynamic Spinal Stabilization Systems,” filed on Sep. 25, 2006; and U.S. Provisional Patent Application 60863284, entitled “Alignment Instrument for Dynamic Spinal Stabilization Systems,” filed on Oct. 27, 2006, the dynamic links  16 A and  16 B may be aligned to rotate about a center of rotation. Thus, in certain embodiments the cross-connector  60  may also be sized to align to a center of rotation. 
         [0040]    As illustrated in  FIG. 3 , an adapter  74  may be coupled to the fastener  70 . In certain embodiments, adapter  74  may have a distal portion for engaging the fastener  70  or the cross connector  60  and a proximal portion for engaging an alignment device, such as alignment rod  76 . In other embodiments, the proximal portion of the adapter  74  may include a head  78  for the attachment of other devices and components. The alignment rod  76  may be inserted into a head  78  of the adapter  74  and thereafter used to align the cross connector  60  with point A. In certain embodiments, the alignment rod  76  may be connected to other adapters  74  and other cross connectors (not shown) along the spine to provide proper alignment. Once the cross connectors and/or the stabilization system  10  and  110  are aligned with point A, the adapter may be used to tighten the fastener  70 . Once fastener  70  is tightened, the elongated members  62  and  64  may be secured from moving in respect to each other, thereby setting the stabilization system  10  and  110  into substantially permanent alignment with point A. 
         [0041]    Referring to  FIG. 4A , there is illustrated one embodiment of the adapter  74  shown in  FIG. 3  that may be used in conjunction with the cross-connector. In this embodiment, the adapter  74  may have an elongated body  80  enabling the adapter  74  to extend away from any anatomy that may interfere with aligning the cross connector  60 . The elongated body  80  may couple to the head  78 . The head  78  may include an orifice  82  that extends in a direction generally transverse to the longitudinal axis of adapter  74 . The orifice  82  may be dimensioned to slidingly receive the alignment rod  76  as shown in  FIG. 3 . A torque transfer feature  88  may be located on head  78  and may interface with a torque transfer device, such as a driver, to aid in positioning adapter  74  and/or tightening fastener  70  to cross connector  60 . 
         [0042]    Referring to  FIG. 4B , an alternative embodiment of an adapter  84  is illustrated. Many of the portions of the adapter  84  may be substantially similar in construction and function to the portions of the adapter  74 . Such similar component parts are designated in  FIG. 4B  with the same reference numerals utilized above in the description of the adapter  74 , but are differentiated therefrom by means of a prime (′) designation. The adapter  84  may differ from the adapter  74  in that, for example, the adapter  84  comprises a different head  78 ′. An elongated body  80 ′ may have a proximal portion that may attach to the head  78 ′. The distal portion of elongated body may couple to cross connector  60  to aid in alignment of the cross-connector  60  and dynamic stabilization constructs  10  and  110 . The head  78 ′ of the adapter  84  may have a channel  86 ′ extending into the top surface of head  78 ′ which may receive the alignment rod  76  such that alignment rod  76  is positioned generally transverse with respect to the longitudinal axis of the adapter  84 . The channel  86 ′ may also interface with a torque transfer device to aid in the insertion of fastener  70 . 
         [0043]    In certain embodiments the adapter  74  (or  84 ) and the alignment rod  76  may be manufactured from metallic materials such as stainless steel, nitinol or titanium. Polymers may also be used to manufacture adapters  74  and  84  and alignment rod  76 . The specific material may be chosen based the surgeon&#39;s desire for the device appear on a fluoroscopy image during surgery which may aid the surgeon in aligning the dynamic stabilization devices  10  and  110  and cross connector  60 . 
         [0044]    Referring to  FIGS. 5A and 5B , another embodiment of a cross-connector  90  is illustrated. The cross-connector  90  may be substantially similar in function but may differ (e.g., in construction) from the cross-connector illustrated in  FIGS. 1 through 3  as described above. For example, the cross-connector  90  may differ from the cross-connector  60  in that cross-connector  90  may comprise a first elongated member  92  which fits within a second elongated member  94 . In certain embodiments, the channel  96  may be substantially straight to receive first elongated member  92  and allow proper sliding between the two members. 
         [0045]    In other embodiments the channel  96  may have curved top and bottom surfaces that correspond to curved surfaces on the first elongated member  92 . The channel  96  may be sufficiently oversized as to allow a gap between the first elongated member  92  and the second elongated member  94 . The gap may allow the two elongated members to slide freely and pivot a controlled degree (based on the size of the gap). The gap may be increased or decrease depending on the desired amount of motion between the first and second elongated members. 
         [0046]    As described above, cross connector  90  may be similar to cross connector  60 . For example, the first and second elongated members  92  and  94  may have a section with a convex top surface and a concave bottom surface to accommodate neighboring anatomy of the spine. 
         [0047]    In certain embodiments the cross connector  90  may have first and second elongated members with exterior gripping portions to attach to the rods  14 C and  14 D as described in earlier embodiments. The gripping portions may have a hook geometry that snap fits around the rods  14 C and  14 D to maintain the position of cross connector  90  while the surgeon secures cross connector  90  into its final position. A set screw may also be used to further secure cross connector  90  to rods  14 C and  14 D as described in the other embodiments above. In other embodiments cross-connector  90  may secure onto the rods  14 C and  14 D of the spine stabilization system  10  and  110  by fasteners which lock the first and second elongated members to the rods without the need for a snap fit type interlock. 
         [0048]    In certain embodiments the second elongated member  96  may have an orifice  98  for receiving a fastener  100  for securing the first and second elongated member  92  and  94  of cross connector  90  together once the desired position of cross-connector  90  is achieved. Once fastener  100  is secured in place cross connector  90  may stabilize and support the spine stabilization constructs  10  and  110  in proper alignment while allowing natural motion of the spine. The cross connector  90  may be aligned in the same manner as cross connector  60  as described above. The fastener  100  may engage adapters  74  and  84  to aid in the use of the alignment rod  76 . 
         [0049]    The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.