Patent Publication Number: US-8114130-B2

Title: Deflection rod system for spine implant with end connectors and method

Description:
CLAIM TO PRIORITY 
     This application claims priority to all of the following applications including U.S. Provisional Application No. 60/942,162, filed Jun. 5, 2007, entitled “Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,260, filed Aug. 1, 2007, entitled “Shaped Horizontal Rod for Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,273, filed Aug. 1, 2007, entitled “Multi-directional Deflection Profile for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,305, filed Aug. 1, 2007, entitled “A Horizontal Rod with a Mounting Platform for a Dynamic Stabilization and Motion Preservation Spinal Implant System and Method”, 
     U.S. patent application Ser. No. 11/832,330, filed Aug. 1, 2007, entitled “Multi-dimensional Horizontal Rod for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,338, filed Aug. 1, 2007, entitled “A Bone Anchor With a Yoke-Shaped anchor head for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,358, filed Aug. 1, 2007, entitled “A Bone Anchor With a Curved Mounting Element for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,377, filed Aug. 1, 2007, entitled “Reinforced Bone Anchor for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,400, filed Aug. 1, 2007, entitled “A Bone Anchor With a Compressor Element for Receiving a Rod for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,413, filed Aug. 1, 2007, entitled “Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method with a Deflection Rod”, 
     U.S. patent application Ser. No. 11/832,426, filed Aug. 1, 2007, entitled “Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method with a Deflection Rod Mounted in Close Proximity to a Mounting Rod”, 
     U.S. patent application Ser. No. 11/832,436, filed Aug. 1, 2007, entitled “Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,446, filed Aug. 1, 2007, entitled “Super-Elastic Deflection Rod for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,470, filed Aug. 1, 2007, entitled “Revision System and Method for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,485, filed Aug. 1, 2007, entitled “Revision System for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,494, filed Aug. 1, 2007, entitled “Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,517, filed Aug. 1, 2007, entitled “Implantation Method for Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,527, filed Aug. 1, 2007, entitled “Modular Spine Treatment Kit for Dynamic Stabilization and Motion Preservation of the Spine”, 
     U.S. patent application Ser. No. 11/832,534, filed Aug. 1, 2007, entitled “Horizontally Loaded Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. patent application Ser. No. 11/832,548, filed Aug. 1, 2007, entitled “Dynamic Stabilization and Motion Preservation Spinal Implantation System with Horizontal Deflection Rod and Articulating Vertical Rods”, 
     U.S. patent application Ser. No. 11/832,557, filed Aug. 1, 2007, entitled “An Anchor System for a Spine Implantation System That Can Move About three Axes”, 
     U.S. patent application Ser. No. 11/832,562, filed Aug. 1, 2007, entitled “Rod Capture Mechanism for Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. Provisional Application No. 61/028,792, filed Feb. 14, 2008, entitled “A Deflection Rod System for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, 
     U.S. Provisional Application No. 61/031,598, filed Feb. 26, 2008, entitled “A Deflection Rod System for a Dynamic Stabilization and Motion Preservation Spinal Implantation System and Method”, and 
     U.S. Provisional Application No. 61/057,340, filed May 30, 2008, entitled “A Spine Implant With A Deflection Rod System Aligned With A Bone Anchor And Method”. 
     All of the afore-mentioned applications are incorporated herein by reference in their entireties. 
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to all of the following applications including U.S. patent application Ser. No. 12/130,335, filed May 30, 2008, entitled “A Deflection Rod System For A Spine Implant Including An Inner Rod And An Outer Shell And Method”; 
     U.S. patent application Ser. No. 12/130,359, filed May 30, 2008, entitled “A Deflection Rod System With A Deflection Contouring Shield For A Spine Implant And Method”; 
     U.S. patent application Ser. No. 12/130,367, filed May 30, 2008, entitled “Dynamic Stabilization And Motion Preservation Spinal Implantation System With A Shielded Deflection Rod System And Method”; 
     U.S. patent application Ser. No. 12/130,377, filed May 30, 2008, entitled “A Deflection Rod System For Spine Implant With End Connectors And Method”; 
     U.S. patent application Ser. No. 12/130,383, filed May 30, 2008, entitled “A Deflection Rod System For A Dynamic Stabilization And Motion Preservation Spinal Implantation System And Method”; 
     U.S. patent application Ser. No. 12/130,395, filed May 30, 2008, entitled “A Deflection Rod System With Mount For Dynamic Stabilization And Motion Preservation Spinal Implantation System And Method”; 
     U.S. patent application Ser. No. 12/130,411, filed May 30, 2008, entitled “A Deflection Rod System With Mount For Dynamic Stabilization And Motion Preservation Spinal Implantation System And Method”; 
     U.S. patent application Ser. No. 12/130,423, filed May 30, 2008, entitled “A Deflection Rod System With A Non-Linear Deflection To Load Characteristic For Dynamic Stabilization And Motion Preservation Spinal Implantation System And Method”; 
     U.S. Patent application Ser. No. 12/130,454, filed May 30, 2008, entitled “A Deflection Rod System Dimensioned For Deflection To A Load Characteristic For Dynamic Stabilization And Motion Preservation Spinal Implantation System And Method”; 
     U.S. Patent application Ser. No. 12/130,457, filed May 30, 2008, entitled “A Deflection Rod System For Use With A Vertebral Fusion Implant For Dynamic Stabilization And Motion Preservation Spinal Implantation System And Method”; 
     U.S. patent application Ser. No. 12/130,467, filed May 30, 2008, entitled “A Dual Deflection Rod System For Dynamic Stabilization And Motion Preservation Spinal Implantation System And Method”; 
     U.S. patent application Ser. No. 12/130,475, filed May 30, 2008, entitled “Method For Implanting A Deflection Rod System And Customizing The Deflection Rod System For A Particular Patient Need For Dynamic Stabilization And Motion Preservation Spinal Implantation System”; 
     U.S. patent application Ser. No. 12/130,032, filed May 30, 2008, entitled “A Spine Implant With A Deflection Rod System Anchored To A Bone Anchor And Method”; 
     U.S. patent application Ser. No. 12/130,095, filed May 30, 2008, entitled “A Spine Implant With A Deflection Rod System Including A Deflection Limiting Shield Associated With A Bone Screw And Method”; 
     U.S. patent application Ser. No. 12/130,127, filed May 30, 2008, entitled “A Spine Implant With A Dual Deflection Rod System Including A Deflection Limiting Shield Associated With A Bone Screw And Method”; and 
     U.S. patent application Ser. No. 12/130,152, filed May 30, 2008, entitled “A Spine Implant With A Deflection Rod System And Connecting Linkages And Method”. 
     All of the afore-mentioned applications are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND OF INVENTION 
     The most dynamic segment of orthopedic and neurosurgical medical practice over the past decade has been spinal devices designed to fuse the spine to treat a broad range of degenerative spinal disorders. Back pain is a significant clinical problem and the annual costs to treat it, both surgical and medical, is estimated to be over $2 billion. Motion preserving devices to treat back and extremity pain has, however, created a treatment alternative to or in combination with fusion for degenerative disc disease. These devices offer the possibility of eliminating the long term clinical consequences of fusing the spine that is associated with accelerated degenerative changes at adjacent disc levels. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of a dynamic spine stabilization system of the invention. 
         FIG. 1A  is a posterior view of the embodiment of  FIG. 1  implanted in a spine. 
         FIG. 2  is a top view of the embodiment of  FIG. 1 . 
         FIG. 3  is a perspective view of an embodiment of a horizontal rod system of the invention for use with a dynamic spine stabilization system such as depicted in  FIG. 1 . 
         FIG. 4  is a perspective view of an alternative embodiment of a horizontal rod system of the invention for use with a dynamic spine stabilization system such as depicted in  FIG. 1 . 
         FIG. 5  is a perspective view of an embodiment of an anchor system of the invention for use with a dynamic spine stabilization system such as depicted in  FIG. 1 . 
         FIG. 6  is another perspective view of the embodiment of the anchor system of  FIG. 5 . 
         FIG. 7  is an exploded perspective view of an alternative embodiment of the anchor system of the invention for use with a dynamic spine stabilization system such as depicted in  FIG. 1 . 
         FIG. 8  is a sectioned view of a portion of embodiment of the alternative anchor system of  FIG. 7  of the invention. 
         FIG. 9  is a side view of the anchor system of  FIG. 7  depicting a degree of freedom of movement of the anchor system of  FIG. 7 . 
         FIG. 9A  is an end view of the anchor system of  FIG. 9 . 
         FIG. 10  is a side view of the anchor system of  FIG. 7  depicting another degree of freedom of movement of the anchor system of  FIG. 7 . 
         FIG. 10A  is an end view of the anchor system of  FIG. 10 . 
         FIG. 11  is a side view of the anchor system of  FIG. 7  depicting yet another degree of freedom of movement of the anchor system of  FIG. 7 . 
         FIG. 11A  is an end view of the anchor system of  FIG. 11 . 
         FIG. 12  is a perspective view of yet another embodiment of the anchor system of the invention. 
         FIG. 13  is an exploded perspective view of the embodiment of the anchor system of the invention of  FIG. 12 . 
         FIG. 14  is a perspective view of yet another embodiment of the anchor system of the invention. 
         FIG. 15  is an exploded perspective view of the embodiment of the anchor system of the invention of  FIG. 14 . 
         FIG. 16  is another exploded perspective view of the embodiment of the anchor system of the invention of  FIG. 14 . 
         FIG. 17  is an exploded perspective view of another embodiment of the anchor system of the invention. 
         FIG. 18  is a perspective view of yet another embodiment of the anchor system of the invention. 
         FIG. 19  is a perspective view of another embodiment of a dynamic spine stabilization system of the invention with another horizontal rod system. 
         FIG. 19A  is a perspective view of another horizontal rod system of the invention as depicted in  FIG. 19  and partially shown in phantom form. 
         FIG. 19B  is an exploded perspective view of the embodiment of  FIG. 19 . 
         FIG. 19C  is a side view of the embodiment of  FIG. 19 . 
         FIG. 20  is a top view of another embodiment of the dynamic spine stabilization of the system of the invention of  FIG. 19 . 
         FIG. 20A  is a top side of the embodiment depicted in  FIG. 19A . 
         FIG. 21  is another perspective view of the embodiment of the dynamic spine stabilization of the invention of  FIG. 19 . 
         FIG. 22  is a side view the embodiment of the horizontal rod system of the invention as depicted in  FIG. 19  configured in a closed position for implantation. 
         FIG. 22A  is an end view of the embodiment depicted in  FIG. 22 . 
         FIG. 23  is a side view partially in phantom form of the horizontal rod system of  FIG. 22 . 
         FIG. 24  is a side view of the embodiment of  FIG. 22  in an open position as used when the embodiment is deployed in a spine. 
         FIG. 25  is an end view of the embodiment depicted in  FIG. 24 . 
         FIG. 26  is a perspective view of yet another embodiment of the horizontal rod system of the invention. 
         FIG. 27  is a side view of the embodiment of the horizontal rod system of the invention of  FIG. 26 . 
         FIG. 28  is a perspective view of still another embodiment of the horizontal rod system of the invention. 
         FIG. 29  is a side view of the embodiment of the horizontal rod system of the invention of  FIG. 28 . 
         FIG. 30  is a top view of another embodiment of the horizontal rod system of the invention as depicted in  FIG. 1  with the horizontal rod system in an undeployed position ready for implantation. 
         FIG. 31  is a top view of the embodiment of the horizontal rod system of  FIG. 30  in a deployed position after implantation. 
         FIG. 32  is a side view, partially in phantom of the embodiment depicted in  FIG. 30 . 
         FIG. 33  is a side view of an alternative embodiment of the horizontal rod system of the invention. 
         FIG. 33A  is a side view of yet another embodiment of the horizontal rod system of the invention. 
         FIG. 34  is a side view of another alternative embodiment of the horizontal rod system of the invention. 
         FIG. 34A  is a perspective view of yet another embodiment of the horizontal rod system of the invention. 
         FIG. 34B  is a side view of the embodiment of  FIG. 34A . 
         FIG. 34C  is a top view of the embodiment of  FIG. 34A . 
         FIG. 35  is a side view of still another alternative embodiment of the horizontal rod system of the invention. 
         FIG. 36  is a side view of yet another alternative embodiment of the horizontal rod system of the invention. 
         FIG. 37  is a side view of another alternative embodiment of the horizontal rod system of the invention. 
         FIG. 38  is a side view of another alternative embodiment of the horizontal rod system of the invention. 
         FIG. 39  is a side view of yet another alternative embodiment of the horizontal rod system of the invention. 
         FIG. 39A  is still another embodiment of the horizontal rod system and the anchor system of the invention. 
         FIG. 39B  is yet another embodiment of the horizontal rod system and the anchor system of the invention. 
         FIG. 40  is a perspective view of another embodiment of a dynamic spine stabilization system of the invention. 
         FIG. 41  is a perspective view of still another embodiment of a dynamic spine stabilization system of the invention. 
         FIG. 42  is a side view of an embodiment of a two level dynamic spine stabilization system of the invention. 
         FIG. 43  is a side view of yet another embodiment of a two level dynamic spine stabilization system of the invention. 
         FIG. 43A  is a side view of an alternative embodiment of a dynamic spine stabilization system of the invention. 
         FIG. 44  is a side view of an embodiment of a fusion system of the invention. 
         FIG. 45  is a side view of an embodiment of a two level fusion system of the invention. 
         FIGS. 45A ,  45 B are perspective and side views of still another fusion system of an embodiment of the invention that has a transition level. 
         FIG. 46  is a flow chart of an embodiment of the method of the invention. 
         FIG. 47  is yet another embodiment of the horizontal rod system of the invention. 
         FIG. 48  is a perspective view of an embodiment of a dynamic spine stabilization system of the invention. 
         FIG. 49  is a posterior view of an embodiment of a dynamic spine stabilization system of the invention. 
         FIG. 50A  is a perspective view of an embodiment of the horizontal rod system and a connector of the invention. 
         FIG. 50B  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 51  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 52  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 53  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 54  is a sectional view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 55A  is a sectional view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 55B  is a sectional view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 56A  is a front view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 56B  is a front view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 57  is a perspective view of an embodiment of a vertical rod system of the invention. 
         FIG. 58  is a perspective view of an embodiment of a lock tab of a connector of the invention. 
         FIG. 59  is a sectional view of an embodiment of a vertical rod system and a connector of the invention. 
         FIG. 60  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 61  is a perspective view of an embodiment of a connector of the invention. 
         FIG. 62A  is a perspective view of an embodiment of a sliding tab of a connector of the invention. 
         FIG. 62B  is a perspective view of an embodiment of a sliding tab of a connector of the invention. 
         FIG. 63  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 64  is a perspective view of an embodiment of a vertical rod of the invention. 
         FIG. 65  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 66  is a perspective view of an embodiment of a connector of the invention. 
         FIG. 67  is a perspective view of an embodiment of a vertical rod of the invention. 
         FIG. 68  is a perspective view of an embodiment of a deflection rod of the invention. 
         FIG. 69  is a perspective and exploded view of an embodiment of a deflection rod of the invention. 
         FIG. 70  is a front view of an embodiment of a deflection rod of the invention. 
         FIG. 71  is a front view of an embodiment of a deflection rod of the invention. 
         FIG. 72A  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 72B  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 72C  is a partial sectional view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 73A  is a perspective view of an embodiment of a horizontal rod system and a connector of the invention. 
         FIG. 73B  is a front view of a an embodiment of horizontal rod system of the invention. 
         FIG. 73C  is a sectional view of an embodiment of a horizontal rod system of the invention. 
         FIG. 74  is a perspective view of an embodiment of a horizontal rod of the invention. 
         FIG. 75  is a perspective view of an embodiment of a horizontal rod of the invention. 
         FIG. 76  is a perspective view of an embodiment of a horizontal rod of the invention. 
         FIG. 77A  is a perspective view of an embodiment of a cam of the invention. 
         FIG. 77B  is a top view of an embodiment of a cam of the invention. 
         FIG. 78  is a perspective view of an embodiment of a cam of the invention. 
         FIG. 79A  is a perspective view of an embodiment of a horizontal rod system and a connector of the invention. 
         FIG. 79B  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 80  is a perspective view of an embodiment of a connector of the invention. 
         FIG. 81  is a perspective view of an embodiment of a connector of the invention. 
         FIG. 82  is a perspective view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 83  is a perspective view of an embodiment of a rotating link of a connector of the invention. 
         FIG. 84  is a sectional view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
         FIG. 85  is a sectional view of an embodiment of a horizontal rod system, a vertical rod system and a connector of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention include a system or implant and method that can dynamically stabilize the spine while providing for preservation of spinal motion. Alternative embodiments can be used for spine fusion. 
     Embodiments of the invention include a construct with an anchoring system, a horizontal rod system that is associated with the anchoring system and a vertical rod system that is associated with the anchoring system and the horizontal rod system. 
     An advantage and aspect of the system is that the anchoring system includes a head or saddle that allows for appropriate, efficient and convenient placement of the anchoring system relative to the spine in order to reduce the force that is placed on the anchoring system. The anchor system has enhanced degrees of freedom which contribute to the ease of implantation of the anchor system. Accordingly, the anchor system is designed to isolate the head and the screw from the rest of the dynamic stabilization system and the forces that the rest of the dynamic stabilization system can place on the anchor system and the anchor system/bone interface. Thus, the anchor system can provide a secure purchase in the spine. 
     Another advantage and aspect of the system is that the horizontal rod system is in part comprised of a super elastic material that allows for convenient positioning of the horizontal rod system relative to the anchor system and allows for isolation of the horizontal rod system from the anchor system so that less force is placed on the anchor system from the horizontal rod system and on the anchor system/bone interface. Accordingly, unlike prior devices the anchor system stays secure in the bone of the spine. 
     An aspect and advantage of the invention is the ability to maximize the range of motion of the spine after embodiments of the dynamic stabilization, motion preservation implant of the invention are implanted in a patient. While traditional solutions to back pain include fusion, discectomy, and artificial implants that replace spine structure, embodiments of the present invention preserve the bone and ligament structure of the spine and preserve a wide range of motion of the spine, while stabilizing spines that were heretofore unstable due to degenerative and other spinal diseases. 
     Still another aspect of the invention is the preservation of the natural motion of the spine and the maintenance of the quality of motion as well as the wide range of motion so that the spine motion is as close to that of the natural spine as possible. The present embodiments of the invention allow for the selection of a less stiff, yet dynamically stable implant for use in a non-fusion situation. A less stiff, yet dynamically stable implant relates directly to a positive patient outcome, including patient comfort and the quality of motion of the spine. 
     In another aspect of the invention, load sharing is provided by the embodiment, and, in particular, the deflection rod or loading rod of the embodiment. For embodiments of this invention, the terms “deflection rod” and “loading rod” can be used interchangeably. Accordingly this aspect of the invention is directed to restoring the normal motion of the spine. The embodiment provides stiffness and support where needed to support the loads exerted on the spine during normal spine motion, which loads, the soft tissues of the spine are no longer able to accommodate since these spine tissues are either degenerated or damaged. Load sharing is enhanced by the ability to select the appropriate stiffness of the deflection rod or loading rod in order to match the load sharing desired. By selecting the appropriate stiffness of the deflection rod or loading rod to match the physiology of the patient and the loads that the patient places on the spine, a better outcome is realized for the patient. Prior to implantation of the embodiment, the stiffness of the implant of the system can be selected among a number of loading rods. In other words, the stiffness is variable depending on the deflection rod or loading rod selected. In another aspect, the load sharing is between the spine and the embodiment of the invention. 
     In another aspect of the invention, the deflection rod or loading rod is cantilevered. In another aspect the deflection rod or loading rod is cantilevered from a horizontal rod. In yet another aspect the deflection rod or loading rod is cantilevered from a horizontal rod that is connected between two anchors that are affixed to the same vertebra. In yet another aspect the deflection rod or loading rod is about parallel to the horizontal rod in a resting position. In still a further, aspect the deflection rod or loading rod is cantilevered from a mount on the horizontal rod and said deflection rod or loading rod is about parallel to the horizontal rod in a resting position. 
     In another aspect of the invention the horizontal rod attached directly to opposite anchors is stiff and rigid, and the cantilevered deflection rod or cantilevered loading rod shares the load with the spine resulting from the motions of the body of the patient. 
     In another aspect of embodiments of the invention, the load being absorbed or carried by the embodiment is being distributed along at least part of the length of the deflection rod or loading rod. In another aspect of the invention, the load being absorbed or carried by the embodiment is distributed along at least part of the length of the horizontal cantilevered deflection rod or horizontal cantilevered loading rod. 
     As the load is carried horizontally along the deflection rod or loading rod, rather than vertically, the embodiments of the invention can be made smaller in order to fit in more spaces relative to the spine. Advantageously, the embodiments can fit in the L 5 -S 1  space of the spine. 
     An aspect of the invention is to preserve and not restrict motion between the pedicles of the spine through the use of appropriately selected horizontal and vertical rods of embodiments of the invention. 
     An aspect of the invention is to provide for load bearing on horizontal elements such as horizontal rods instead of vertical elements or rods, and, in particular, vertical elements that are connected between bone anchoring systems. 
     An aspect of the invention is the use of horizontal rods in the embodiments of the invention in order to isolate each level of the implantation system from the other so as not to put undue force and/or torque on anchoring systems of embodiment of the invention and associated bone, and so as to allow customization of the implantation system to the need of the patient. Accordingly, an aspect of the invention is to provide for minimized loading on the bone/implantation system interface. Customization, in preferred embodiments, can be achieved by the selection of the horizontal rod with the desired stiffness and stiffness characteristics. Different materials and different implant configurations enable the selection of various stiffness characteristics. 
     Another aspect of the invention is the ability to control stiffness for extension, flexion, lateral bending and axial rotation, and to control stiffness for each of these motions independently of the other motions. 
     An aspect of the invention is to use the stiffness and load bearing characteristics of super elastic materials. 
     Another aspect of the invention is to use super elastic materials to customize the implant to the motion preservation and the dynamic stabilization needs of a patient. An aspect of such embodiments of the invention is to provide for a force plateau where motion of the implantation system continues without placement of additional force of the bone anchor system, or, in other words, the bone/implantation system interface. 
     Thus, an aspect of the invention is to use the horizontal bar to offset loading on the anchor system and on the implantation system in general. 
     Accordingly, an aspect of the invention is to be able to selectively vary the stiffness and selectively vary the orientation and direction that the stiffness is felt by varying the structure of the implantation system of the invention, and, in particular, to vary the stiffness of the horizontal rod system of the invention. 
     Another aspect of embodiments of the invention is to prevent any off-axis implantation by allowing the implantation system to have enhanced degrees of freedom of placement of the implant. Embodiments of the invention provide for off-axis placement of bone anchor or pedicle screw systems. 
     A further aspect of embodiments of the invention is to control stabilized motion from micro-motion to broad extension, flexion, axial rotation, and lateral bending motions of the spine. 
     Yet another aspect of the embodiments of the invention is to be able to revise a dynamic stabilization implant should a fusion implant be indicated. This procedure can be accomplished by, for example, the removal of the horizontal rods of the implantation system and replacement of such rods with stiffer rods. Accordingly, an aspect of the invention is to provide for a convenient path for a revision of the original implantation system, if needed. 
     A further aspect of the invention, due to the ease of implanting the anchoring system and the ease of affixing vertical rods to the horizontal rods of the invention, is the ability to accommodate the bone structure of the spine, even if adjacent vertebra are misaligned with respect to each other. 
     A further aspect of the invention is that the implant is constructed around features of the spine such as the spinous processes and, thus, such features do not need to be removed and the implant does not get in the way of the normal motion of the spine features and the spine features do not get in the way of the operation of the implant. 
     Another aspect of embodiments of the invention is the ability to stabilize two, three and/or more levels of the spine by the selection of appropriate embodiments and components of embodiments of the invention for implantation in a patient. Further embodiments of the invention allow for fused levels (in conjunction with, if desired, bone graphs) to be placed next to dynamically stabilized levels with the same implantation system. Such embodiments of the invention enable vertebral levels adjacent to fusion levels to be shielded by avoiding an abrupt change from a rigid fusion level to a dynamically stable, motion preserved, and more mobile level. 
     Accordingly, another aspect of the embodiments of the invention is to provide a modular system that can be customized to the needs of the patient. Horizontal rods can be selectively chosen for the particular patient as well the particular levels of the vertebrae of the spine that are treated. Further, the positioning of the various selected horizontal rods can be selected to control stiffness and stability. 
     Another aspect of embodiments of the invention is that embodiments can be constructed to provide for higher stiffness and fusion at one level while allowing for lower stiffness and dynamic stabilization at another adjacent level. 
     Yet a further aspect of the invention is to provide for dynamic stabilization and motion preservation while preserving the bone and tissues of the spine in order to lessen trauma to the patient and to use the existing functional bone and tissue of the patient as optimally as possible in cooperation with embodiments of the invention. 
     Another object of the invention is to implant the embodiments of the invention in order to unload force from the spinal facets and other posterior spinal structures and also the intervertebral disk. 
     A further aspect of the invention is to implant the embodiment of the invention with a procedure that does not remove or alter bone or tear or sever tissue. In an aspect of the invention the muscle and other tissue can be urged out of the way during the inventive implantation procedure. 
     Accordingly, an aspect of the invention is to provide for a novel implantation procedure that is minimally invasive. 
     Dynamic Stabilization, Motion Preservation System for the Spine: 
     A dynamic stabilization, motion preservation system  100  embodiment of the invention is depicted in  FIG. 1  and includes an anchor system  102 , a horizontal rod system  104 , and a vertical rod system  106 . For these embodiments horizontal refers to a horizontal orientation with respect to a human patient that is standing and vertical refers to a vertical orientation with respect to a patient that is standing ( FIG. 1A ). As will be more fully disclosed herein below, one embodiment for the anchor system  102  includes a bone screw  108  which is mounted to a head or saddle  110 . Alternatively, the bone screw  108  can be replaced by a bone hook as more fully described in U.S. Provisional Patent Application No. 60/801,871, entitled “An Implant Position Between the Lamina to Treat Degenerative Disorders of the Spine,” which was filed on Jun. 14, 2006, and is incorporated herein by reference and in its entirety. The mounting of the head or saddle  110  to the bone screw  108  allows for multiple degrees of freedom in order that the bone screw  108  may be appropriately, conveniently, and easily placed in the bone of the spine and in order to assist in isolating the bone screw  108  from the remainder of the system  100  so that less force is placed on the anchor system  102  and on the bone screw/bone interface. Some prior art devices, which use such bone screws, have, on occasion, had the bone screws loosen from the spine, and the present embodiment is designed to reduce the force on the bone screw and on the bone screw/bone interface. Preferably, the anchor system  102  is comprised of titanium. However, other biocompatible materials such as stainless steal and/or PEEK can be used. 
     In the embodiment of  FIG. 1 , the horizontal bar system  104  is preferably secured through the head  110  of the anchor system  102  with a locking set screw  112 . This embodiment includes a first horizontal rod  114  and a second horizontal rod  116 . The first horizontal rod  114  has first and second deflection rods or loading rods  118  and  120  secured thereto. In a preferred embodiment, the first horizontal rod can be comprised of titanium, stainless steel or PEEK or another biocompatible material, and the first and second deflection rods or loading rods can be comprised of a super elastic material. Preferably, the super elastic material is comprised on Nitinol (NiTi). In addition to Nitinol or nickel-titanium (NiTi), other super elastic materials include copper-zinc-aluminum and copper-aluminum-nickel. However, for biocompatibility, the nickel-titanium is the preferred material. 
     Such an arrangement allows for the horizontal rod system  104  to isolate forces placed thereon from the anchor system  102  and, thus, isolate forces that could be placed on the bone screw  108  and the bone screw/bone interface of the spine, and, thus, prevent the loosening of the bone screw  108  in the spine. As shown in  FIG. 1  the deflection rods or loading rods  118  and  120 , in this preferred embodiment, are mounted in the center of the first horizontal rod  114  to a mount  122 . Preferably, the deflection rods or loading rods  118  and  120  are force fit into the mount  122 . Alternatively, the deflection rods or loading rods may be screwed, glued, or laser welded to the mount  122  and to bores placed in the mount  122 . Other fastening techniques are within the scope and spirit of the invention. As can be seen in  FIGS. 1 ,  3 , and  4 , the first horizontal rod  114  includes first and second ridges  124 ,  126  located on either side of the mount  122  and extend at least partially along the length of the first horizontal rod  114  toward the respective ends of the horizontal rod  114 . These ridges  124 ,  126  add rigidity to the mount  122  relative to the rest of the horizontal rod system  104 . 
     As seen in  FIG. 1 , the deflection rods or loading rods  118 ,  120  have a constant diameter extending outwardly toward the respective ends  128 ,  130  of the deflection rods or loading rods  118 ,  120 . Alternatively, the deflection rods or loading rods  118 ,  120  can have a varying diameter as the rods  118 ,  120  approach their respective ends  128 ,  130 . Preferably, as depicted and discussed below, the rods  118  and  120  can have a decreasing diameter as the rods approach the respective ends  128 ,  130 . The decreasing diameter allows the super elastic rods  118 ,  120  to be more flexible and bendable along the length of the rods as the rods approach the ends  128 ,  130  and to more evenly distribute the load placed on the system  100  by the spine. Preferably, the diameter of the deflection rods or loading rods continuously decreases in diameter. However, it can be understood that the diameter can decrease in discrete steps along the length, with the diameter of one step not being continuous with the diameter of the next adjacent step. Alternatively, for different force and load carrying criteria the diameters of the deflection rods or loading rods can continuously increase in diameter or can have discreet step increases in diameter along the length of the deflection rods or loading rods as the rods extent toward the respective ends  128 ,  130 . Still further, the rods can have at least one step of decreasing diameter and at least one step of increasing diameter in any order along the length of the deflection rods or loading rods as the rods approach the respective ends  128 ,  130 , as desired for the force and load carrying characteristics of the deflection rods or loading rods  118 ,  120 . 
     With respect to  FIG. 3 , for example, the horizontal rod system  104 , and, in particular, the deflection rods  118 ,  120 , share the load carried by the spine. This load sharing is directed to restoring the normal motion of the spine. This embodiment, and, in particular, the deflection rods or loading rods  118 ,  120 , provide stiffness and support where needed to support the loads exerted on the spine during spine motion, which loads, the soft tissues of the spine are no longer able to accommodate since these spine tissues are either degenerated or damaged. Such load sharing is enhanced by the ability to select the appropriate stiffness of the deflection rods or loading rods  118 ,  120  in order to match the load sharing desired. By selecting the appropriate stiffness of the deflection or loading rods, to match the physiology of the patient, and the loads that the patient places on the spine, a better outcome is realized by the patient. Prior to implantation, the stiffness of the deflection or loading rods can be selected from a number of deflection or loading rods. The stiffness is variable depending on the deflection or load rod selected. As indicated herein, the stiffness of the deflection or loading rod can be varied by the shape of the rod and the selection of the material. Shape variations can include diameter, taper, direction of taper, stepped tapering, and material variation can include composition of material, just to name a few variations. 
     It is to be understood that the load carried by the deflection or loading rods is distributed along at least part of the length of the deflection or loading rods. Preferably, the load is distributed along the entire length of the deflection or loading rods. Further, as the load is carried horizontally and the stiffness can be varied along a horizontal member, rather than vertically, the embodiments of the invention can be made smaller in order to fit in more spaces relative to the spine. Advantageously, embodiments can fit, for example, in the L 5 -S 1  space of the spine in addition to generally less constrained spaces such as the L 4 -L 5  space of the spine. 
     With respect to the embodiment of the horizontal rod system of the invention as depicted for example in  FIG. 3 , the deflection rods or loading rods  118 ,  120  are cantilevered from mount  122 . Thus, these deflection rods  118 ,  120  have a free end and an end fixed by the mount  112 , which mount is located on the horizontal rod  114 . As is evident in  FIG. 3 , the cantilevered deflection rods  118 ,  120  are about parallel in a rested position to the horizontal rod  114 , and, in this embodiment, the horizontal rod is directly connected to the anchor systems and, in particular, to the heads or saddles of the anchor system. Preferably, the horizontal rod  114  is stiff and rigid and, particularly, in comparison to the deflection rods. In this arrangement, the horizontal rod system and, in particular, the deflection rods  118 ,  120  share the load resulting from the motions of the body of the patient. 
     As an alternate embodiment, the second horizontal rod  116  could be replaced with a horizontal rod  114  which has deflection rods or loading rods ( FIG. 43A ). Thus, both horizontal rods would have deflection rods or loading rods. The deflection rods or loading rods mounted on one horizontal rod would be connected to vertical rods and the vertical rods would be connected to deflection rods or loading rods mounted on the other horizontal rod. Such an embodiment provides for more flexibility. Further, the deflection rods or loading rods  118 ,  120  can have other configurations and be within the spirit and scope of the invention. 
     Further, as can be seen in  FIG. 1 , the vertical rod system is comprised of, in this embodiment, first and second vertical rods  132 ,  134  which are secured to first and second connectors  136 ,  138  located at the ends  128 ,  130  of the first and second deflection rods or loading rods  118 ,  120 . As will be described below, the vertical rods  132 ,  134  are preferably connected in such a way as to be pivotal for purposes of implantation in a patient and for purposes of adding flexibility and dynamic stability to the system as a whole. These vertical rods  132 ,  134  are preferably made of titanium. However, other bio-compatible materials can be used. The vertical rods  132 ,  134  are also connected to the second horizontal rod  116  by being received in C-shaped mounts  140 ,  142  located on the second horizontal rods and in this embodiment, held in place by set screws  144 , 146 . It is to be understood by one of ordinary skill in the art that other structures can be used to connect the vertical rods to the horizontal rods. 
     Preferably, the vertical rods are only connected to the horizontal rods and not to the anchoring system  102  in order to isolate the anchor system  102  and, in particular, the heads  110  from stress and forces that could be placed on the heads, and from forces transferred to the heads where the vertical rods connect to the heads. Thus, the system  100  through the vertical and horizontal rods allow for dynamic stability, and a wide range of motion without causing undue force to be placed on the heads of the anchor systems. These embodiments also allow for each level of the spine to move as freely as possible without being unduly restrictively tied to another level. 
     More lateral placement of the vertical rods toward the heads of the anchor system provides for more stiffness in lateral bending and an easier implant approach by, for example, a Wiltse approach as described in “The Paraspinal Sacraspinalis-Splitting Approach to the Lumber Spine,” by Leon L. Wiltse et al.,  The Journal of Bone  &amp;  Joint Surgery , Vol. 50-A, No. 5, July 1968, which is incorporated herein by reference. 
     The stiffness of the system  100  can preferably be adjusted by the selection of the materials and placement and diameters of the horizontal and vertical rods and also the deflection rods or loading rods. Larger diameter rods would increase the resistance of the system  100  to flexion, extension rotation, and bending of the spine, while smaller diameter rods would decrease the resistance of the system  100  to flexion, extension, rotation and bending of the spine. Further, continually or discretely changing the diameter of the rods such as the deflection rods or loading rods along the length of the rods changes the stiffness characteristics. Thus, with the deflection rods or loading rods  118 ,  120  tapered from the mount  122  toward the ends  128 ,  130 , the system can have more flexibility in flexion and extension of the spine. Further, using a super elastic material for the horizontal rods and the vertical rods in addition to the horizontal deflection rods or loading rods adds to the flexibility of the system  100 . Further, all of the horizontal and vertical rods, in addition to the deflection rods or loading rods, can be made of titanium or stainless steel or PEEK should a stiffer system  100  be required. Thus, it can be appreciated that the system  100  can easily accommodate the desired stiffness for the patient depending on the materials uses, and the diameter of the materials, and the placement of the elements of the system  100 . 
     Should an implanted system  100  need to be revised, that can be accomplished by removing and replacing the horizontal and/or vertical rods to obtain the desired stiffness. By way of example only, should a stiffer revised system be desired, more akin to a fusion, or, in fact, a fusion, then the horizontal rods having the deflection rods or loading rods can be removed and replaced by horizontal rods having deflection rods or loading rods made of titanium, or stainless steel, or non-super elastic rods to increase the stiffness of the system. This can be accomplished by leaving the anchor system  102  in place and removing the existing horizontal rods from the heads  110  and replacing the horizontal rods with stiffer horizontal rods and associated vertical rods. 
       FIG. 3  depicts a view of the horizontal rod  104  as previously described. In this embodiment the connectors  136 ,  138  are shown on the ends of the deflection rods or loading rods  118 ,  120 . The connectors can be forced-fitted to the deflection rods or fastened in other methods known in the art for this material and as further disclosed below. The connectors  136 ,  138  have slits  148 ,  150  to aid in placing the connectors onto the ends of the deflection rods. As is evident from  FIG. 3 , the connectors  136 ,  138  each include upper and lower arms  160 ,  162  which can capture there between the vertical rods  132 ,  134 . The arms each include an aperture  168 ,  170  that can accept a pin or screw  176 ,  178  ( FIG. 1 ) for either fixedly or pivotally securing the vertical rods  132 ,  134 . In this embodiment the vertical rods include a head  162 ,  164  that can be force fit or screwed onto the rest of the vertical rods. The heads include apertures  172 ,  174  for accepting the pins or screws  176 ,  178 . 
     In order that the system  100  has as low a profile as possible and extends from the spine as little as possible, it is advantageous to place the deflection rods or loading rods  118 ,  120  as close to the first horizontal rod  114  as possible. In order to accomplish this low profile, preferably notches  152 ,  154  are placed in horizontal rod  114  to accommodate the connectors  136 ,  138 . 
     Accordingly, the purpose for the notches is to provide for a horizontal rod with a low profile when implanted relative to the bones and tissues of the spine so that there is, for example, clearance for implant and the motion of the implant, and to keep the deflection rods or loading rods as close as possible to the horizontal rods in order to reduce any potential moment arm relative to the mounts on the horizontal rod. 
       FIG. 4  depicts another embodiment of the horizontal rod  114  with deflection rods or loading rods  118 ,  120  and with different connectors  156 ,  158 . Connectors  156 ,  158  each include two pairs of upper and lower arms  160 ,  162  extending in opposite directions in order for each connector  156 ,  158  to mount an upper and a lower vertical rod as presented with respect to  FIG. 46 . This configuration allows for a three level system as will be described below. 
     Embodiments of the Anchor System of the Invention 
     A preferred embodiment of the anchor system  102  invention can be seen in  FIG. 5 . This is similar to the anchor system  102  depicted in  FIG. 1 . In particular, this anchor system  102  includes a bone screw  108  with a head  110  in the form of a U-shaped yoke  180  with arms  182 ,  184 . As will be discussed further, a hook, preferably with bone engaging barbs or projections, can be substituted for the bone screw  108 . The hook embodiment is further described in the above referenced and incorporated provisional application. The hooks are used to hook to the bone, such as the vertebra instead of having screws anchored into the bone. Each of the arms  182 ,  814  of yoke  180  includes an aperture  186 ,  188  through which a pin  190  can be placed. The pin  190  can be laser welded or force fit or glued into the yoke  180 , as desired. The pin  190  can be smooth or roughened as discussed below. Further, the pin  190  can be cylindrical or be comprised of a multiple sides as shown in  FIG. 7 . In  FIG. 7 , pin  190  has six sides and one or more of the accommodating apertures  186 ,  188  can also include mating sides in order to fix the position of the pin  190  in the yoke  180 . A compression sphere  200  is placed over the pin  190 . The compression sphere  200  can have a roughened surface if desired to assist in locking the sphere in place as described below. The compression sphere  200  can include one or more slits  202  to assist in compressing the sphere  200  about the pin  190 . The compression sphere  200  can have an inner bore that is cylindrical or with multiple sides in order conform to and be received over the pin  190 . As can be seen in  FIG. 8 , one or more spacer rings  204  can be used to space the compression ring from the yoke  180  in order to assist in providing the range of motion and degrees of freedom that are advantageous to the embodiments of the invention. 
     Mounted about the compression sphere  200  is the head or saddle  110 . Head  110  in  FIGS. 7 ,  8  is somewhat different from head  110  in  FIG. 1  as will be described below. Head  110  in  FIGS. 7 ,  8  includes a cylindrical body  206  with a lower end having an aperture  208  that can receive the compression sphere  200 . The aperture  208  can have a concave surface as depicted in  FIGS. 7 ,  8 . Accordingly, the compression sphere  200  fits inside of the concave surface of aperture  208  and is free to move therein until restrained as described below. As is evident from the figures, the lower end of the cylindrical body  206  about the aperture  208  has some of the material that comprised wall  224  removed in order to accommodate the motion of the yoke  180  of the bone screw  108 . Essentially, the portion of the wall  224  adjacent to the arms  182 ,  184  of the yoke  180  has been removed to accommodate the yoke  180  and the range of motion of the yoke. 
     The head  110  of the anchor system  102  includes an internal cylindrical bore  210  which is preferably substantially parallel to a longitudinal axis of the head  110 . This bore  210  is open to the aperture  208  and is open and preferably substantially perpendicular to the distal end  212  of the head  110 . At the distal end  212  of the head  110 , the bore  210  is threaded and can accept the set screw  112 . Along the side of the head  110  are defined aligned U-shaped slots that extend through the head  110  from the outer surface to the bore  210 . These U-shaped slots are also open to the distal end  212  of the head  110  in order to have the set screw  112  accepted by the threads of the bore  210 . Located in the bore  210  between the set screw  112  and the compression sphere  200  is a compressor element or cradle  220 . The compressor element or cradle  220  can slide somewhat in the bore  210 , but the compressor element or cradle  220  is restrained by a pin  222  ( FIG. 7 ) received through the wall  224  of the head  110  and into the compressor element or cradle  220 . Thus, the compressor element or cradle  220 , until locked into position, can move somewhat in the bore  210 . 
     The compressor element or cradle  220  has a generally cylindrical body so that the compressor element  220  can fit into bore  210 . An upper end  226  of the compressor element  220  includes a concave surface  228 . This surface  228  is shaped to fit the horizontal rod system  104  and, in particular, a horizontal rod  114 ,  116 . The lower end of the compressor element  220  includes a concave surface  230  which can accommodate the compression sphere  200 . The lower end of the compressor element  220  adjacent to the concave surface  230  has an additional concave surface  232  ( FIG. 8 ) which is used to accommodate the motion of the upper end of the yoke  180  as the head  110  is moved relative to the bone screw  108 . The concave surfaces  228  and  230  can be roughened, if desired, to assist in locking the head  110  relative to the bone screw  108 . In this embodiment ( FIGS. 5 ,  6 ) there is no top compression element or cradle (see, for example,  FIGS. 7 ,  13 ) in order to reduce the profile of the head of the anchor system. 
     As is evident from the figures, with the anchor system  102  assembled and with a horizontal rod  114 ,  116  received in the U-shaped slot  216 , the set screw can press against the horizontal rod  114 ,  116 , which horizontal rod  114 ,  116 , can press against the compressor element or cradle  220 , which compressor element or cradle  220  can press against the compression sphere  220 , which compression sphere can press against the pin  190  in order to lock the horizontal rod  114 ,  116  relative to the head  110  and to lock the head  110  relative to the bone screw  108 . It is to be understood that all of the surfaces that are in contact, can be roughened to enable this locking, if desired. Alternatively, the surfaces may be smooth with the force of the set screw  112  urging of the elements together and the resultant locking. 
     As can be seen in  FIGS. 5 ,  6  an alternative horizontal rod  114 ,  116  is depicted. This alternative horizontal rod  114 ,  116  includes first and second concave openings  234 ,  236  which can receive vertical rods such as vertical rods  132 ,  134  ( FIG. 1 ). The horizontal rod  114 ,  116  is substantially cylindrical with the areas around the concave openings  234 ,  236  bulked up or reinforced as desired to support the forces. Additionally, threaded bores are provided adjacent to the concave openings  234 ,  236  and these bores can receive screws that have heads that can be used to lock vertical rods in place. Alternatively, the screws can retain short bars that project over the concave openings  234 ,  236  in order to hold the vertical rods in place ( FIG. 34 ). If desired, the short retaining bars can also have concave openings that conform to the shape of, and receive at least part of, the vertical rods in order to retain the vertical rods in place with the system  100  implanted in a patient. 
     Turning again to  FIGS. 1 ,  2 ,  5 ,  6 , the head  110  depicted is a preferred embodiment and is somewhat different from the head  110  as seen in  FIG. 8 . In particular the head body  206 , the outer surface  218  of the head and the head wall  224 , have been configured in order to prevent splaying of the head  110  when the set screw  112  locks the anchor system  102  as explained above. As seen in  FIGS. 1 ,  2 , the head  110  and, in particular, the wall  224  is reinforced about the U-shaped slot  216  that received the horizontal bar system  104 . By reinforcing or bulking up the area of the wall about the U-shaped slot  216 , splaying of the head  110  when force is applied to the set screw  214 , in order to lock the anchor system  102 , is avoided. The head  110  can use a number of shapes to be reinforced in order to prevent splaying. The exemplary embodiment of  FIGS. 1 ,  2 , includes a pitched roof shape as seen in the top view looking down on distal end  212  of the head  110 . In particular, the wall about the U-shaped slot  216  is thickened, while the portion of the head distal from the U-shaped slot can be less thick if desired in order to reduce the bulk and size of the head  110  and, thus, give the head  110  a smaller profile relative to the bone and tissue structures when implanted in a patient. Further, the small profile allows greater freedom of motion of the system  100  as described below. Also, it is to be understood that due to the design of the anchor system  102 , as described above, the head  110  can be shorter and, thus, stand less prominently out of the bone when the bone screw  108  in implanted in a spine of a patient for example. 
     Freedom of Motion of the Embodiments of the Anchor System of the Invention 
     In order to accommodate embodiments of the horizontal rod systems  104  of the invention, to allow greater freedom in placing the horizontal rod systems and the anchor systems  102  relative to, for example, the spine of a patient, and to provide for a smaller implanted profile in a patient, the anchor system  102  includes a number of degrees of freedom of motion. These degrees of freedom of motion are depicted in  FIGS. 9 ,  9 A,  10 ,  10 A, and  11 ,  11 A. 
       FIG. 9  establishes a frame of reference including a longitudinal axis x which is along the longitudinal length of the bone screw  108 , a y axis that extends perpendicular to the x axis, and a lateral axis z which is perpendicular to both the x axis and the y axis and extends outwardly from and parallel to the pin  190  of the yoke  180  of the anchor system  102 . As depicted in the figures and, in particular,  FIGS. 9 ,  9 A, the system  100  due to the embodiments as disclosed herein is able to have the head  110  rotate about the z axis from about 80 degrees to about zero degrees and, thus, in line with the x axis and from the zero degree position to about 80 degrees on the other side of the x axis. Accordingly, the head is able to rotate about 160 degrees about the z axis relative to the bone screw  108 . As seen in  FIGS. 10 ,  10 A the head  110  is able to tilt about 0.08 inches (2 mm) relative to and on both sides of the x axis. Accordingly, the head  110  can tilt from about 12 degrees to zero degrees where the head  110  is about parallel to the x axis and from zero degrees to 12 degrees about the y axis and on the other side of the x axis. Thus, the head can tilt through about 24 degrees about the y axis. As can be seen in  FIGS. 11 ,  11 A, the head  110  can swivel for a total of about 40 degrees about the x axis. With respect  FIG. 11A , the head  110  can swivel about the x axis from about 20 degrees to one side of the z axis to zero degrees and from zero degrees to about 20 degrees on the other side of the z axis. The head is able to substantially exercise all of these degrees of freedom at once and, thus, can have a compound position relative to the bone screw by simultaneously moving the head within the ranges of about 160 degrees about the z axis ( FIG. 9 ), about 24 degrees from the y axis ( FIG. 10 ) and about 40 degrees about the x axis ( FIG. 11A ). 
     Thus, with respect to  FIGS. 9 ,  9 A the range of motion in the axial plane is about 180 degrees or about 90 degrees on each side of the centerline. In  FIGS. 10 ,  10 A the range of motion in the Caudal/Cephalad orientation is about 4 mm or about 2 mm on each side of the centerline or about 24 degrees or about 12 degrees on each side of the centerline. In  FIGS. 11 ,  11 A the range of motion in the coronal plane is about 40 degrees or about 20 degrees on each side of the centerline. 
       FIGS. 12 ,  13  depict yet another embodiment of the anchor system  102  of the invention where elements that are similar to elements of other embodiments and have similar reference numbers. 
     As can be seen in  FIG. 13 , this embodiment includes a lower cradle or compressor element  220  that is similar to the cradle or compressor element  220  of the embodiment of  FIG. 7  with the head  110  similar to the head  110  as seen in  FIG. 7 . The compression sphere  200  is similar to the compression sphere  200  in  FIG. 7  with the compression sphere including a plurality of slits provided about the axis of rotation  238  of the sphere  200 . In this embodiment, the slits  202  have openings that alternate between facing the north pole of the axis of rotation of the sphere  200  and facing the south pole of the axis of rotation of the sphere  200 . Alternatively, the slits can be provided in the sphere and have no opening relative to the north or south pole of the axis of rotation of the sphere  200 . Still further, the slits can open relative to only one of the north or south poles. 
     In the embodiment of  FIGS. 12 ,  13 , there is also an upper cradle or compressor element  240  which is positioned adjacent to the set screw  214  (see also  FIG. 7 ). The upper cradle or compressor element  240  has a generally cylindrical body which can slide in the cylindrical bore of the head  110  with an upper end having fingers  242  extending therefrom. The fingers  242  can spring over a bore formed in the lower surface of the set screw  214  in order to retain the cradle  240  relative to the set screw  214  and to allow the cradle  240  to rotate relative to the set screw  214 . The lower surface of the cradle  240  includes a concave surface  244  which can mate with a horizontal rod  114 ,  116  in order to lock the rod relative the head  110  and the head  110  relative to the bone screw  108 . If desired, the concave surface  244  can be roughened to assist in locking the system  100 . 
     Further, in  FIGS. 12 ,  13 , a retaining ring  246  is depicted. The retaining ring can be force fit over the outer surface  218  of the head  110 , or pop over and snap under a ridge  248  at the distal end  212  of the head  110 , or can have internal threads that mate with external threads located on the outer surface of the  218  of the head  110 . With the anchor system  102  in place in a patient and with the horizontal rod  114 ,  116  received in the anchor system, before the set screw  214  is tightened in order to lock the horizontal rod and the anchor system, the retaining ring  246  can be attached to the head  110  in order to prevent splaying of the head  110  as the set screw  214  locks the system  110 . 
     Further embodiments of the anchor system  102  which can side load the horizontal rods  114 ,  116  are seen in  FIGS. 14 ,  15 , and  16 , where similar elements from other embodiments of the anchor system are given similar numeral references. With respect to the embodiment in  FIG. 15 , the head side wall  224  includes a lateral or side opening  250  which communicates with the cylindrical bore  210  which is located in head  110 . The lateral or side opening preferably extends more than 180 degrees about the outer surface of the head. The side opening  250  includes a lip  252  and the side opening extends down below the lip into communication with the cylindrical bore  210  and follows the outline of the concave surface  228  of the cradle  220 . Accordingly, a horizontal rod  114 ,  116 , can be positioned through the side opening  250  and urged downwardly into contact with the concave surface  228  of the cradle  220 . In this embodiment the cradle  220  includes a downward projecting post  254 . Also, this embodiment does not include a compression sphere, and instead the pin  190 , which can have a larger diameter than a pin  190  in other embodiments, comes in direct contact with the post  254  when the set screw  112  locks the anchor system  100 . If desired the pin  190  can have a roughened surface  256  to assist in the locking of the anchor system  100 . As is evident from  FIGS. 14 ,  15 ,  16 , as this embodiment has a side loading head  110 , the distal end of the head is a fully cylindrical without communicating with any lateral U-shaped slots of the other embodiments. Accordingly, this embodiment does not include any retaining ring or reinforced areas that can be used to prevent splaying. 
       FIG. 17  depicts yet another embodiment of the anchor system  102  that has a lateral or side loading head  110 . In this embodiment, a compression cylinder  258  is placed over the pin  190 . Such a compression cylinder  258  may offer less freedom of motion of the anchor system  100  with added stability. The compression cylinder  258  can slide along the longitudinal axis  260  of the pin  190 , if desired. The head  110  can rotate about the pin  190  and the compression cylinder  258 . The head  110  can also slide or translate along the longitudinal axis  260  of the pin as well as the longitudinal axis of the compression cylinder  258 . Compression cylinder  258  has slits  262  that can be configured similarly as the slits  202  of the other embodiments of the anchor system  100  described and depicted herein. 
       FIG. 18  depicts still another embodiment of the anchor system  100  that has a lateral or side loading head  110 . This embodiment includes a compression sphere  200  provided over a pin  190  which is similar to the other compression spheres  200  depicted and described herein. Accordingly, this embodiment has the freedom of motion described with respect to the other embodiments which use a compression sphere. 
     It is to be understood that although each embodiment of the anchor system does not necessarily depict all the elements of another embodiment of the anchor system, that one of ordinary skill in the art would be able to use elements of one embodiment of the anchor system in another embodiment of the anchor system. 
     Embodiments of the Horizontal Rod System of the Invention 
     Embodiments of the horizontal rod system  104  of the invention include the embodiments describes above, in addition to the embodiments that follow. An aspect of the horizontal rod system  104  is to isolate the anchor system  102  and reduce the stress and forces on the anchor system. This aspect is accomplished by not transmitting such stresses and forces placed on the horizontal rod system by, for example, flexion, extension, rotation or bending of the spine to the anchor system. This aspect thus maintains the integrity of the placement of the anchor system in, for example, the spine and prevents loosening of the bone screw or bone hook of the anchor system. In addition, various horizontal rod systems can be used to control the rigidity, stiffness and/or springiness of the dynamic stabilization system  100  by the various elements that comprise the horizontal rod system. Further the horizontal rod system can be used to have one level of rigidity, stiffness and/or springiness in one direction and another level in a different direction. For example, the horizontal rod system can offer one level of stiffness in flexion of the spine and a different level of stiffness in extension of the spine. Additionally, the resistance to lateral bending can be controlled by the horizontal rod system. Select horizontal rod systems allow for more resistance to lateral bending with other select horizontal rod systems allow for less lateral bending. As discussed below, placement of the vertical rods also effects lateral bending. The more laterally the vertical rods are placed, the more stiff the embodiment is to lateral bending. 
     As is evident from the figures, the horizontal rod system connects to the heads of the anchor system without the vertical rod system connecting to the heads. Generally, two anchor systems are secured to each vertebral level with a horizontal rod system connected between the two anchor systems. This further ensures that less stress and force is placed on the anchor systems secured to each level and also enables dynamic stability of the vertebra of the spine. Accordingly, movement of the vertebra relative to each other vertebra, as the spine extends, flexes, rotates and bends, is stabilized by the horizontal rods and the entire system  100  without placing excessive force or stress on the anchor system as there are no vertical rods that connect the anchor systems of one vertebra level with the anchor system of another vertebra. 
     With respect to  FIG. 19  through  FIG. 25  another embodiment of the horizontal rod system  304  of the dynamic stabilization system  300  is depicted as used with an anchor system  102  of the embodiment depicted in  FIG. 1 . Also shown in  FIGS. 19 ,  19 A, is the vertical rod system  306 . The horizontal rod system  304  includes first and second horizontal rods  308 ,  310 . It is to be understood that  FIG. 19A  shows a second image of only the horizontal rod  308  in a first undeployed position and that  FIG. 19  shows a deployed position with the horizontal rod  308  connected with vertical rods  306  and, thus, the entire system  300 . 
     The horizontal rod  308  includes first and second aligned end rods  312 ,  314  which are connected together with an offset rod  316  located between the first and second end rods  312 ,  314 . In this embodiment, the horizontal rod  308  looks much like a yoke with the offset rod joining each of the end rods  312 ,  314  with a curved section  318 ,  320 . At the junction of the first end rod  312  and the offset rod  316  is a first bore  322  which is aligned with the first end rod  312 , and at the junction of the second end rod  314  and the offset rod  316  is a second bore  324  which is aligned with the second end rod  314  and, thus, aligned with the first end rod  312 . Positioned in and extending from the first bore  322  is a first deflection rod or loading rod  326  and positioned in and extending from the second bore  324  is a second deflection rod or loading rod  328 . As with the other deflection rods or loading rods, preferably deflection rods or loading rods  324 ,  328  are made of a super elastic material such as, for example, Nitinol (NiTi) and the rest of system  300  is comprised of titanium, stainless steel, a biocompatible polymer such as PEEK or other biocompatible material. In addition to Nitinol or nickel-titanium (NiTi), other super elastic materials include copper-zinc-aluminum and copper-aluminum-nickel. However, for biocompatibility the nickel-titanium is the desired material. The super elastic material has been selected for the deflection rods as the stress or force/deflection chart for a super elastic material has a plateau where the force is relatively constant as the deflection increases. Stated differently, a super elastic rod has a load (y) axis/deflection (x) axis curve which has a plateau at a certain level where the load plateaus or flattens out with increased deflection. In other words, the rod continues to deflect with the load staying constant at the plateau. In one embodiment, the load plateau is about 250 Newtons to about 300 Newtons. It is to be understood that the plateau can be customized to the needs of the patient by the selection of the type and composition of the super elastic material. For some patients, the plateau should be lower, and, for others, the plateau should be higher. Accordingly, and, for example, at the plateau, additional force is not put on the anchor system  102  and, thus, additional force is not put on the area of implantation of the bone screw  108  and the surrounding bone of the spine where the bone screw  108  is implanted. The deflection rods or loading rods  326 ,  328  are force fit, screwed, welded, or glued into the bores  322 ,  324  as desired. 
     The first and second deflection rods or loading rods  326 ,  328  extend from the respective bores  322 ,  324  toward each other and are joined by a Y-shaped connector  330 . The Y-shaped connector  330  includes a base  332  which has opposed and aligned bores  334 ,  336  that can receive the deflection rods or loading rods  326 ,  328  in a manner that preferably allows the Y-shaped connector to pivot about the longitudinal axis defined by the aligned first and second deflection rods or loading rods  326 ,  328 . The Y-shaped connector  330  includes first and second arms that preferably end in threaded bores  342 ,  344  that can receive the threaded ends of the vertical bar system  306  as described below. Just behind the threaded bores  342 ,  344  are recesses  346 ,  348  ( FIG. 24 ) which are shaped to accept the offset rod  316  with the horizontal rod  308  in the undeployed configuration depicted in  FIG. 19A . In the undeployed configuration, the horizontal rod  308  can be more easily implanted between the tissues and bones of the spine and, in particular, guided between the spinous processes. Once the first horizontal rod  308  is implanted, the Y-shaped connector  330  can be deployed by rotating it about 90 degrees or as required by the anatomy of the spine of the patient and connected with the vertical rod system  306 . 
     The second horizontal rod  310  is similar to the second horizontal rod  116  of the embodiment of  FIG. 1 . This second horizontal rod  310  is preferably comprised of titanium or other biocompatible material and includes first and second mounts  350 ,  352  which can receive the ends of the vertical rod system  306 . The mounts  350 ,  352  include respective recesses  354 ,  356  which can receive the vertical rods  358 ,  360  of the vertical rod system  306 . The mounts  350 ,  352  also include tabs  362 ,  364  which can capture the vertical rods  358 ,  360  in the respective recesses  354 ,  356 . The tabs  362 ,  364  can be secured to the mounts  350 ,  352  with screws or other appropriate fastening devices. 
     The first and second vertical rods  358 ,  360  are preferably comprised of titanium or other biocompatible material and include a threaded end and a non-threaded end. The threaded end can be formed on the end of the rod or threaded elements can be force fit or glued to the end of the vertical rods  358 ,  360 . Once the first and second horizontal rods are deployed in the patient, the first and second vertical rods can be screwed into or otherwise captured by the Y-shaped connector  330  of the first horizontal bar  308  and the first and second vertical rods can be captured or otherwise secured to the second horizontal bar  310 . 
       FIGS. 26 ,  27 , and  FIGS. 28 ,  29  depict yet more alternative embodiments of the horizontal rod systems of the invention. The horizontal rod  370  in  FIG. 26 ,  27  is similar to the horizontal rod  118  in  FIG. 1 . Horizontal rod  370  includes a mount  372  which has bores that can receive first and second deflection rods or loading rods  374 ,  376  which are preferably made of a super elastic material. At the ends of the first and second deflection rods or loading rods  374 ,  376  are connectors which include a tab having a threaded bore therethrough. The connectors can be used to connect vertical rods to the deflection rods or loading rods. 
       FIGS. 28 ,  29  depict a horizontal rod  380  with first mount  382  and second mount  384 . Each of the mounts  382 ,  884 , includes a bore that is substantially parallel to the horizontal rod  380 . First and second deflection rods or loading rods  386 ,  388  extend respectively from the bores of the first and second mounts  382 ,  382 . In the embodiment depicted the deflection rods or loading rods  386 ,  388  are parallel to the horizontal rod  380  and are directed toward each other. Alternatively, the deflection rods or loading rods  386 ,  388  can be directed away from each other. In that configuration, the mounts  382 ,  384  would be spaced apart and the deflection rods or loading rods would be shorter as the deflection rods or loading rods extended parallel to and toward the ends of the horizontal rod  380 . 
       FIGS. 30 ,  31 ,  32  depict yet another embodiment of the horizontal rod system  390  of the invention which is similar to the horizontal bar system  104  as depicted in  FIG. 1 . Horizontal bar system  390  includes tapered deflection rods or loading rods  392 ,  394 . The deflection rods or loading rods are tapered and reduce in diameter from the mount  396  toward the ends of the horizontal rod  390 . As previously discussed the deflection rods or loading rods can taper continuously or in discrete steps and can also have an decreasing diameter from the ends of the deflection rods or loading rods towards the mount  396 . In other words, a reverse taper than what is depicted in  FIG. 30 . Connected to the deflection rod or loading rods  392 ,  394  are the vertical rods  402 ,  404 . The vertical rods  402 ,  404  are connected to the deflection rods or loading rods  392 ,  394  as explained above. 
     The conically shaped or tapered deflection rods or loading rods can be formed by drawing or grinding the material which is preferably a super elastic material. The tapered shape of the deflection rods or loading rods distributes the load or forces placed by the spine on the system evenly over the relatively short length of the deflection rods or loading rods as the rods extend from the central mount outwardly toward the ends of the horizontal rod. In this embodiment, in order to be operatively positioned relative to the spine and between the anchor systems, the deflection rods or loading rods are less than half the length of the horizontal rods. 
       FIG. 30  depicts the vertical rods  402 ,  404  in undeployed positions that are about parallel to the horizontal rod  390  and with the vertical rods  402 ,  404  directed away from each other and toward the respective ends of the horizontal rod  390 . In this position the horizontal rod  390  can be more conveniently directed through the bone and tissue of the spine and, for example, directed between the spinous processes to the implant position. Once in position, the vertical rods  402 ,  404  can be deployed so that the vertical rods are parallel to each other and about parallel to the horizontal rod  390  as depicted in  FIG. 31 . Accordingly, this embodiment can be inserted from the side of the spine in the undeployed configuration depicted in  FIG. 30  and then the vertical rods can be rotated or deployed by about 90 degrees (from  FIG. 30  to  FIG. 31 ) each into the coronal plane of the patient. The vertical rods are also free to rotate about 180 degrees about the deflection rods and in the sagittal plane of patient. This allows this embodiment to conform to the different sagittal contours that may be encountered relative to the spine of a patient. The deflection rods or loading rods are rigidly connected to the horizontal rod allowing for an easier surgical technique as sections of the spine and, in particular, the spinous processes and associated ligaments and tissues do not have to be removed in order to accommodate the implantation system  100 . The moving action of the system, and, in particular, the flexing of the deflection rods and the motion of the vertical rods connected to the deflection rods or loading rods, takes place about the spinous processes and associated tissues and ligaments, and, thus, the spinous processes do not interfere with this motion. Further, having the horizontal rods more lateral than central also allows for a more simple surgical technique through, for example, a Wiltse approach. 
     To assist in implantation, a cone  406  can be slipped over the end of the horizontal rod  390  and the vertical rod  402  to assist in urging the tissues and bone associated with the spine out of the way. Once the horizontal rod is implanted the cone  406  can be removed. The cone  406  includes an end  408  which can be pointed or bulbous and the cone  406  has an increasing diameter in the direction to the sleeve  410  portion of the cone  406 . The sleeve can be cylindrical and receive the end of the horizontal rod and the end of the deflection rod or loading rod  402 . 
       FIG. 32  depicts how the connectors  412 ,  414  are secured to the respective deflection rods  392 ,  394 . The deflection rods have flanges, such as spaced apart flange  416 ,  418  on the deflection rod  392 . The connectors  412 ,  414  can snap over and be retained between respective pairs of flanges. 
       FIG. 33  depicts yet another embodiment of the horizontal rod system  430  of the invention. The horizontal rod system  430  includes horizontal rod  432  which is preferably comprised of a super elastic material such as Nitinol. The horizontal rod  432  includes a generally central platform  434 , and on each side of the central platform  434  are first and second upwardly facing scallops or recesses  436 ,  438 . On each side of the upwardly facing scallop or recess  436  are downwardly facing scallops or recesses  440 ,  442 . On each side of the upwardly facing scallop or recess  438  are downwardly facing scallops or recesses  444 ,  446 . The platform  434  accepts a connector for connecting the horizontal rod to vertical rods ( FIG. 40 ) as will be explained below, and the scallops  436 ,  440 ,  442  on one side of the platform  434  act as a spring and the scallop  438 ,  444 ,  446  on the other side of the platform  434  acts as a spring. These springs assist the platform in carrying the load that the spine can place on the horizontal rod and isolate the anchor systems  102  from that load. That isolation has the advantage of preventing loosening of the anchor system as implanted in the patient. It is to be understood that by varying the pattern of the scallops, that the stiffness or rigidity of the horizontal bar can be varied and customized for each patient. Fewer scallops will generally result in a more stiff horizontal bar and more scallops will generally result in a less rigid horizontal bar. Additionally, the stiffness can be different depending on the direction of the force that is placed on the horizontal bar depending on the orientation and location of the scallops. For the embodiment depicted in  FIG. 33 , with the scallops  436 ,  438  pointed upward to the head of a patient and the scallops  440 ,  442 ,  444 ,  446  pointed downward toward the feet of a patient, the horizontal bar is stiffer in extension and less stiff in flexion. It is noted that in this embodiment the rod is of a uniform diameter, although the diameter can be non-uniform as, for example, being larger where the platform  434  is and tapering to the ends of the horizontal rod  432 , or having a large diameter at the ends of the horizontal rod  432 , tapering to a smaller diameter at the platform  434 . In this embodiment with a substantially uniform diameter, the scallops are formed within the uniform diameter. In other forms, the scallops are molded into the horizontal rod or machined out of the preformed horizontal rod. With this configuration, the horizontal rod is more easily inserted into the spine and between bones and tissues of the spine. Further, this horizontal rod can be more easily delivered to the spine through a cannula due to the substantially uniform diameter. For purposes of forming the scallops a machining technique known as wire electric discharge machining or wire EDM can be used. Thus, an approach for shaping the super elastic material is through wire EDM followed by electro-polishing. Additionally, the super elastic material in this and the other embodiments can be cold rolled, drawn or worked in order to increase the super elastic property of the material. 
     In this embodiment, the deflection takes place almost exclusively in the middle portion of the horizontal rod and principally at the platform and spring thus relieving the load or force on the ends of the horizontal rod and on the anchor system/bone interface. 
     Accordingly, in this preferred embodiment, there are two superior scallops pointing upwardly having a relatively gentler radius compared to the tighter radii of the inferior scallops pointing downwardly. It is to be understood that in this preferred embodiment, the inferior scallops are not symmetrical the way the superior scallops are. The lateral most cuts in both of the most lateral inferior scallops are steep and not radiused. These cuts allow the rod to bend at these points enhancing the spring effect. The ratio of the radii of the superior scallop to the inferior scallop in this preferred embodiment is two to one. The result is to create two curved and flat (in cross-section) sections, one on each side of the platform and these two flat sections in this preferred embodiment have about the same uniform thickness. Again, in this embodiment, the scallops and the platform is formed into an otherwise uniformly diametered cylindrical rod. Accordingly, none of these formed elements in this preferred embodiment extend beyond the diameter of the rod. In this preferred embodiment, the diameter of the horizontal rod is about 4 mm. 
     If desired, the rod could be bent in such a way that the platform and/or the scallops extend outside of the diameter of the cylindrical rod. However that configuration would not be as suitable for implantation through a cannula or percutaneously as would the horizontal rod as shown in  FIG. 33  and described above. 
     It is to be understood that to have enhanced flexibility, that the torsion rod and connector elements used in the horizontal rod embodiment of  FIG. 1  can be used with the horizontal rod of  FIG. 33 . In this embodiment ( FIG. 47 ), the connector is secured to the platform of the horizontal rod of  FIG. 33  with the two deflection rods or loading rods extending toward the ends of the horizontal rod of  FIG. 33  and about parallel to that horizontal rod. 
     Another embodiment of the horizontal rod  433  is depicted in  FIG. 33A . In this embodiment the horizontal rod  433  is similar to the horizontal rod in  FIG. 33  with the exception that the platform and scallops are replaced with a reduced diameter central portion  448 . Each end of the central portion  448  gradually increases in diameter until the diameter is the full diameter of the ends of the horizontal rod  433 . This embodiment can be formed of a super elastic material and ground to the reduced diameter shape from a rod stock of the super elastic material. The rod stock could also be drawn to this shape. Generally after such operations the horizontal rod would be electro polished. In this embodiment, a connector such as the connector shown in  FIG. 40  could be used to connect vertical rods to preferably the middle of the central portion  448 . 
       FIGS. 34A ,  34 B,  34 C depict yet an alternative embodiment of a horizontal rod  280  such as horizontal rod  116  as shown in  FIG. 1  that is meant to rigidly hold the vertical rods secured thereto. The mounts  282 ,  284  formed in this horizontal rod  280  include a body that can be formed with the rod  280 . The mounts are then provided with a movable capture arm  286 ,  288  that have recesses, which capture arms are formed out of the mount preferably using a wire EDM process that leaves the capture arm still connected to the horizontal rod with a living hinge. Eccentric headed set screws  290 ,  292  are mounted on the horizontal bar. With vertical rods captured in the recesses of the capture arms, the eccentric set screws can be turned to urge the capture arms against the living hinge, and thereby capturing the vertical rods in the recesses of the capture arms. 
       FIG. 40  depicts a dynamic stabilization system  450  that uses the horizontal rod system  454  of the invention. The system  450  additionally uses the anchor system  102  as depicted in  FIG. 1  and the other horizontal rod  310  as depicted in  FIGS. 19 ,  34 . A connector  452  is secured to the platform  434  of the horizontal rod  454  and vertical rods are connected to the connector and to the other horizontal rod  310 . In  FIG. 40  for the horizontal rod  454 , the scallops are formed by bending a bar and not by forming the scallops in a straight horizontal bar as depicted in the horizontal bar  432  of  FIG. 33 . The horizontal rod  430  of  FIG. 33  could also be used in the embodiment of  FIG. 40 . 
       FIG. 35  depicts an alternative embodiment of a horizontal rod system  460  of the invention. Horizontal rod system  460  includes a horizontal rod  462  with a central platform  464  and first and second spring regions  466 ,  468  located on either side of the platform  464 . Extending outwardly from each spring region are respective ends of the horizontal rod  462 . The spring regions include coils that are wound about the longitudinal axis of the horizontal rod  462 . If desired, the entire horizontal rod  462  can be comprised of a rod wound around a longitudinal axis with the platform  464  and the ends of the horizontal rod being more tightly wound and/or with a smaller diameter and the spring regions  466 ,  468  more loosely wound and/or with a larger diameter. Such a horizontal rod  462  can preferably be comprised of super elastic material such as Nitinol or alternatively titanium or other biocompatible material which demonstrates the ability to flex repeatedly. 
       FIG. 36  depicts yet another alternative embodiment of a horizontal rod system  480  which includes first and second horizontal rods  482 ,  484  which can be flat rods if desired. The horizontal rods  482 ,  484 , include spring region  494 ,  496 . In the spring region the horizontal rod is formed into an arc, much like a leaf spring. Located at the ends and at the central platform  486  and between the horizontal rods  482 ,  484  are spacers  488 ,  490 ,  492 . The spacers are glued, bonded, welded or otherwise secured between the first and second horizontal rods  482 ,  484  in order to form the horizontal rod system  480 . This system  480  can be comprised of super elastic materials or other materials that are biocompatible with the patient. 
       FIG. 37  depicts another embodiment of the horizontal rod system  500  including a horizontal rod  502 . In this embodiment, recesses  504  are formed in the horizontal rod in order to define the stiffness of the horizontal rod  502 . This system can be formed of a super elastic material or other biocompatible material. 
       FIG. 38  depicts still another embodiment of the horizontal rod system  520  of the invention with a horizontal rod  522 . The horizontal rod  522  includes dimples  524  distributed around and along the horizontal rod  522 . As this other embodiment, depending on the distribution of the dimples, the stiffness of the horizontal rod  522  can be determined. Further is more dimples are placed on the lower surface than on the upper surface, when placed in a patient, the horizontal rod  522  would tend to be stiffer in extension and less stiff in flexion. This horizontal rod  522  can also be made of a super elastic material or other biocompatible material. 
       FIG. 39  depicts another embodiment of the horizontal rod system  530  of the invention which has a horizontal rod  532  which is similar to the horizontal rod  432  of  FIG. 33  and, thus, similar elements will number with similar numbers. In addition, the ends  534 ,  536  of the horizontal rod  532  are curved so as to create hooks that can fit around portions of the vertebra so as to secure the horizontal rod  532  to the vertebra. In this embodiment, preferably the rod is comprised of super elastic material or other biocompatible material. In order to implant the rod, the hooks at ends  534 ,  536  are sprung open and allowed to spring closed around the vertebra. An anchor system which includes a hook (as discussed above) could be used with this system. 
       FIGS. 39A ,  39 B are similar to  FIG. 39 . In  FIGS. 39A ,  39 B, a horizontal rod  532  is held in place relative to the spine by two anchor systems  102 . The anchor systems are similar to the anchor systems depicted in  FIG. 1 . The anchor systems  102  include an anchor or bone screw  108  or bone hook  109  with spikes  111  ( FIG. 39B ), as well as the head  110  into which the horizontal rod is received. A set screw  112  secures the horizontal rod relative to the anchor systems. 
       FIG. 41  depicts another embodiment of the dynamic stabilization system  540  of the invention. This embodiment includes side loading anchor systems  542  as described above, although top loading anchor systems would also be appropriate for this embodiment. In this embodiment the horizontal rods  544 ,  546  are preferably comprised of a polymer such as PEEK and mounted on the horizontal rods  544 ,  546  are first and second connectors  548 ,  550 . Vertical rods  552  and  554  are connected to the first and second connectors  548 ,  550  at points  556  with screws, rivets or other devices so that the connection is rigid or, alternatively, so that the vertical rods  552 ,  554  can pivot or rotate about the points. As the horizontal rods are comprised of PEEK, the system tends to be more rigid than if the rods were comprised of a super elastic material. Rigidity also depends on the diameter of the rod. 
     Embodiments of the Vertical Rod System of the Invention 
     Embodiments of vertical rod systems of the invention such as vertical rod system  106  are presented throughout this description of the invention. Generally, the vertical rod systems are comprised of vertical rods that can be pivoted or inserted into position after the horizontal rods are deployed in the patient. The vertical rods are preferably connected to the horizontal rods and not to the anchor systems in order to reduce the forces and stress on the anchor systems. The vertical rods are connected to the horizontal rod systems, which horizontal rod systems include mechanisms as described herein that reduce the forces and stresses on the anchor systems. The vertical rods can generally be comprised of titanium, stainless steel, PEEK or other biocompatible material. Should more flexibility be desired, the vertical rods can be comprised of a super elastic material. 
     Embodiments of Alternative Multi-Level Dynamic Stabilization Systems for the Spine 
       FIGS. 42 and 43  depict multi-level dynamic stabilization systems  560 ,  580 . Each of these systems  560 ,  580  are two level systems. All of these systems use anchor systems as described herein. In system  560  of  FIG. 42  the middle level horizontal rod  562  is secured to a vertebra and includes a horizontal rod system  104  having first and second deflection rods or loading rods such as that depicted in  FIG. 4 , whereby a first pair of vertical rods  564  can extend upwardly from horizontal rod system and a second pair of vertical rods  566  can extend downwardly from the horizontal rod system. The vertical rods that extend upwardly are connected to an upper horizontal rod  568  such as depicted in  FIG. 34  and the vertical rods that extend downward are connected to a lower horizontal rod  568  such as depicted in  FIG. 34 . The upper horizontal rod  568  is secured with anchor systems to a vertebra located above the vertebra to which the middle level horizontal rod  562  is secured. The lower horizontal rod  570  is secured with anchor systems to a vertebra located below the vertebra to which the middle level horizontal rod  562  is secured. This embodiment offers more stability for the middle level vertebra relative to the upper and lower vertebra while allowing for extension, flexion, rotation and bending relative to the middle level vertebra. 
       FIG. 43  depicts another multi-level dynamic stabilization system  580 . All of these systems use anchor systems as described herein. In system  580  of  FIG. 43 , the middle level horizontal rod  582  is secured to a vertebra and includes a horizontal rod such as that depicted in  FIG. 34 . The upper and lower horizontal rods  586 ,  590  can be similar to the horizontal rod  114  including the deflection rods or loading rods and deflection rod or loading rod mount depicted in  FIG. 3 . Vertical rods are pivotally and rotationally mounted to the upper and lower horizontal rods  586 ,  590  and, respectively, to the deflection or loading rods thereof and are also rigidly mounted to the middle level horizontal rod  582 . The upper horizontal rod  586  is secured with anchor systems to a vertebra located above the vertebra to which the middle level horizontal rod  582  is secured. The lower horizontal rod  590  is secured with anchor systems to a vertebra located below the vertebra to which the middle level horizontal rod  582  is secured. This embodiment offers more dynamic stability for the upper and lower vertebra relative to the middle level vertebra while allowing for extension, flexion, rotation and bending relative to the middle level vertebra. Alternatively, the middle level horizontal rod  582  has four mounts instead of the two mounts depicted in  FIG. 34  or  FIG. 34A  so that a first pair of vertical rods  588  can extend upwardly from a lower horizontal rod  590  and a second pair of vertical rods  566  extending downwardly from the upper horizontal rod  586 , can be secured to the middle level horizontal rod  582 . 
     Embodiments of Spine Fusion Systems of the Invention 
       FIGS. 44 ,  45  depict one and two level systems that are more preferably used for fusion. The system  600  depicted in  FIG. 44  resembles the system depicted in  FIG. 41 . When PEEK is used for the horizontal rods  602 ,  604 , the system is substantially rigid and can be used in conjunction with spine fusion. For example, this system can be used with the placement of bone or a fusion cage between vertebra to which this system is attached. In fusion, bone can be placed between the vertebral bodies or, alternatively, fusion can be accomplished by placing bone in the valleys on each side of the spinous processes. The horizontal rods  602 ,  604  an also be comprised of titanium, or other biocompatible material and be used for spine fusion. For this embodiment, the vertical rods  606  can be rigidly attached to the horizontal rods through the use of a horizontal rod with mounts, as depicted in  FIG. 34 , so that the vertical rods  606  do not move or pivot with respect to the horizontal rods. 
       FIG. 45  depicts a two level system  620  that is more preferably used for a two level fusion. Each level can use an anchor system for example described with respect to anchor system  102  of  FIG. 1 . The horizontal rods  622 ,  624 ,  626  are can be similar to the horizontal rod in  FIG. 34  with either two vertical rod mounts for the upper and lower horizontal rods  622 ,  626  or four vertical rod mounts for the middle level horizontal rod  624 . For this embodiment, the vertical rods  628 ,  630  can be rigidly attached to the horizontal rods through the use of a horizontal rod with mounts as depicted in  FIG. 34  so that the vertical rods  628 ,  630  do not move or pivot with respect to the horizontal rods. Vertical rods  628  extend between the upper and middle horizontal rods  622 ,  624 , and vertical rods  630  extend between the middle and lower horizontal rods  624 ,  626 . The system  620  depicted in  FIG. 44  resembles the system depicted in  FIG. 41 , but with respect to three levels. When PEEK is used for the horizontal rods  622 ,  624 ,  626 , the system is substantially rigid and can be used in conjunction with spine fusion. For example, this system can be used with the placement of bone or a fusion cage between vertebra to which this system is attached. Bone can also be placed along the valleys on either side of the spinous processes for this system. The horizontal rods  622 ,  624 ,  626  can also be comprised of titanium, PEEK or other biocompatible material and be used for spine fusion. 
     With respect to  FIG. 45 , to ease the transition to a one level fused area of the spine this two level system can be modified by replacing the horizontal rod  622  with a horizontal rod  115  ( FIGS. 45A ,  45 B), which is much like horizontal rod  104  with deflection or loading rods  118 ,  120  of  FIG. 1 . This embodiment is depicted in  FIG. 45A . Thus, fusion is accomplished between the two lower horizontal rods  117  which rods are like those depicted in  FIG. 34 , or like horizontal rods  116  in  FIG. 1 , and made of, preferably, titanium, and flexibility is provided by the upper horizontal rod  115  that is like horizontal rod  114  with deflection or loading rods that are shown in  FIG. 1 . Accordingly, there is more gradual transition from a healthier portion of the spine located above horizontal rod  115  through horizontal rod  115  to the fused part of the spine located between horizontal rod  624  and horizontal rod  606  of  FIG. 45  or between the horizontal rods  117  ( FIG. 45A ). 
     Further Embodiments of the Dynamic Stabilization System and Embodiments of the Connectors, the Horizontal Rod System, and the Vertical Rod System 
     Various embodiments of the dynamic stabilization system have been shown and described above.  FIGS. 48-85  provide further embodiments of the dynamic stabilization system. Referring now to  FIGS. 48 and 49 , perspective and posterior views of another embodiment of a dynamic stabilization system  700  can be seen. Generally, as with the embodiments described above, the dynamic stabilization system  700  includes an anchor system  702 , a horizontal rod system  704  and a vertical rod system  706 . For these embodiments horizontal refers to a horizontal orientation with respect to a human patient that is standing and vertical refers to a vertical orientation with respect to a patient that is standing. The horizontal rod system  704  can include a first horizontal rod  708 , a second horizontal rod  710  and a deflection rod system  712 . The vertical rod system  706  can include vertical rods  716  which are used with separate connectors  718  to attach the vertical rods  716  to the deflection rod system  712  attached to the first horizontal rod  708  and can use connector  1210  to attach vertical rods  716  to the second horizontal rod  710 . 
     As shown in  FIGS. 48-49 , the deflection rod system  712  is attached, in this embodiment, to the center of the first horizontal rod  708  within a mount  714 , while being connected to the vertical rods  716  at the ends  722 ,  724  of the deflection rod system  712 . The deflection rod system  712  is positioned about parallel to the first horizontal rod  708 , the first horizontal rod  708  being attached to the anchor systems  702  and, in particular, to the heads or saddles of the anchor system  702 . Preferably, the horizontal rods  708 ,  710  are stiff and rigid (and made of titanium, for example), particularly in comparison to the deflection rod system  712  (which can be made of a super elastic material such as Nitinol (inner deflection rod  720  ( FIG. 50A ) and a polymer such as PEEK (outer shell  721 ), for example). In this configuration, the horizontal rod system  704  and, in particular, the deflection rod system  712  shares and distributes the load resulting from the motions of the body of the patient. Various embodiments of the vertical rods  716 , the connectors  718 ,  1210 , the deflection rod system  712 , and the horizontal rods  708 ,  710  can be utilized as a part of the dynamic stabilization system  700  as will be described in greater detail below. 
       FIGS. 50A-55B  illustrate an embodiment of a deflection rod system  712 , a vertical rod  716  and a connector  718  used within the dynamic stabilization system  700 . Referring now to  FIGS. 50A-55B , the deflection rod system  712  includes an inner deflection rod  720  having a first end  722  and a second end  724 , a retaining ring  726  and a spherical ball or joint  728 . As will be further described with regard to  FIGS. 68-71 , the deflection rod system  712  includes an inner rod  720  preferably made of, for example, a super elastic material such as Nitinol, and an outer shell  721  made of a polymer such as PEEK. In this embodiment, the first end  722  of the inner deflection rod  720  of the deflection rod system  712  can be passed through the retaining ring  726  and attached to the spherical ball or joint  728  (as shown in  FIG. 51 ) using threading, fusing, gluing, press fit and/or laser welding techniques, for example. In this embodiment, the spherical ball or joint  728  is only connected to the deflection rod  720  and not to the outer shell  721  of the deflection rod system  712 . The spherical joint  728  can then be positioned within the socket chamber  768  of the connector  718 . Once the spherical joint  728  is positioned within the connector  718 , the retaining ring  726  can be threaded, fused, glued, press fit and/or laser welded, for example, to the connector  718 , thereby securing the deflection rod  712  to the connector  718  (as shown in  FIG. 52 ) in a ball joint type connection. In this configuration, the deflection rod system  712  is allowed to rotate and/or have tilting and/or swiveling movements about a center which corresponds with the center of the spherical ball or joint  728 . 
     Referring to  FIGS. 51 and 52 , the vertical rod  716  used in this embodiment of the dynamic stabilization system  700  includes a head  730  having an aperture  732  that can accept a screw  734  and a rectangular shell or recess  736  for accepting the connector  718 . Turning additionally to  FIGS. 53 and 54 , the aperture  732  of the vertical rod  716  includes a first bore  738  and a second bore  740 . The first bore  738  of the aperture  732  can be configured to encase the head  742  of the connector screw  734  while the second section  740  can be configured to capture the neck  735  of the screw  734 . Accordingly, the first section  738  of the aperture  732  has a larger diameter than the second bore  740  of the aperture  732 , the overall shape of the aperture  732  conforming to the shape of the connector screw  734 . 
     Referring back to  FIG. 52 , the rectangular shell or recess  736  of the vertical rod head  730  is configured to fixedly receive and encase the connector  718 . Accordingly, the inner surface of the rectangular shell or recess  736  includes a top surface  746 , inner side surfaces  748 ,  750 , and inner front and back surfaces  752 ,  754 . In this embodiment, the top  746 , front  752  and back  754  inner surfaces are flat and rectangular in shape, while the inner sides surfaces  748 ,  750  are flat with a saddle-shaped cut-out which can allow for movement of the deflection rod system  712  and/or the vertical rod  716  relative to each other. Also in this embodiment, the bottom surface  756  of the head  730  is elevated from the bottom surface  758  of the vertical rod shaft  760  in order to provide a space for the connector  718  to be attached to the bottom of the head  730 . The extent of elevation can vary depending on the size of the connector  718  attached thereto. 
     Referring back to  FIG. 51 , the connector  718  used in this embodiment of the dynamic stabilization system  700  includes a threaded aperture  762  for accepting the connector screw  734  and a housing  764  for accepting the deflection rod system  712 . In its deployed position, the aperture  762  within the connector  718  is lined up with and placed adjacent to the aperture  732  located on the vertical rod  716 , the connector screw  734  being inserted into both apertures  732 ,  762  to secure the connector  718  to the vertical rod  716 . 
       FIGS. 51 and 52  further illustrates the housing  764  of the connector  718  as having a generally cylindrical exterior surface  765  with a flat top surface  766 . The housing  764  also includes an opening  770  on the front face  772  of the connector  718  leading to a socket or spherical chamber  768  formed within the housing  764 . The socket or spherical chamber  768  can be configured to engage the spherical ball or joint  728  of the deflection rod system  712 . In this configuration, the spherical ball or joint  728  of the deflection rod system  712  is allowed to be pivotally engaged to the connector  718  within the socket or spherical chamber  768  while the deflection rod  720  is allowed to extend away from the connector  718  through the opening  770  of the front face  772  of the housing  764 . The retaining ring  726  holds the ball  728  in place in the connector  718 . 
     Referring back to  FIG. 52 , as the aperture  732  in the vertical rod  716  is aligned with the aperture  762  in the connector  718 , the vertical rod recess or shell  736  can also be aligned with the housing  764  of the connector  718 . The connector housing  764  can be inserted into the vertical rod recess or shell  736  until the connector housing  764  engages the top  750  and sides  748 ,  750 ,  752 ,  754  along the inner surface of the vertical rod shell  736 . In this configuration, movement of the connector  718  within the head  730  of the vertical rod  716  is minimized and/or eliminated. This configuration also allows the vertical rod shell  736  to absorb any pressure resulting from movements of the deflection rod system  712  and vertical rod  716  during use, thereby limiting the pressure placed on the screw  734  during use. 
       FIG. 55A  further illustrates the connection between the deflection rod system  712 , the connector  718  and the vertical rod  716  in this embodiment. As can be seen in  FIG. 55A , the retainer ring  726  has an outer diameter which is slightly smaller than the diameter of the opening  770  on the front face  772  of the connector  718 . The retainer ring  726  has a flat front surface  774 , while the inner surface of the retaining ring  726  includes a curved section  776 , the radius of curvature for the curved section  776  being the same as the radius of curvature of the spherical ball or joint  728 . Accordingly, the retaining ring  726  can be inserted into the opening  770  through the front face  772  of the connector  718  until it is in sliding engagement with the spherical joint ball or  728 . The connector  718  can also include a ridge  778  on its inner surface which limits the depth of insertion of the retainer ring  726  into the connector  718 . The retainer ring  726  can then be screwed, fused, glued, force fit, and/or laser welded to the connector  718 . 
       FIG. 55B  illustrates an alternative fastening technique. In this embodiment, the spherical ball or joint  728  is inserted into the connector  718  through an opening  780  on the back face  780  of the connector  718  while the deflection rod  720  is inserted into the connector  718  through an opening  770  on the front face  772  of the connector  718 . Once the parts have been inserted, the spherical joint  728  and the deflection rod  720  are connected within the connector  718 . Alternatively, the spherical ball or joint  728  and the deflection rod  720  can be preassembled by, for example, screwing, gluing, force fitting and/or laser welding before the spherical joint  728  is placed in the connector  718 . A retainer ring  726  can then be used to prevent the spherical joint  728  from exiting the connector  718  through the opening  780  on the back face  782  of the connector  718 . The retainer ring  726  may be screwed, fused, glued, force fit and/or laser welded to the connector  718 . Other fastening techniques are also within the scope and spirit of the invention. 
     Once the deflection rod system  712  is secured to the connector  718 , the connector  718  can then be secured to the vertical rod  716  as shown in  FIG. 53 . In this configuration, the connector  718  is mated with the head  730  of the vertical rod  716 . When mating the connector  718  to the head  730  of the vertical rod  716 , the aperture  732  in the vertical rod  716  is aligned with the aperture  762  of the connector  718 . The connector screw  734  then can secure the vertical rod  716  to the connector  718 . 
       FIGS. 56A-59  illustrate another embodiment of a deflection rod system  800 , a vertical rod  802  and a connector  804  that can be used within the dynamic stabilization system  700 . In this embodiment, a cylindrically-shaped connector  804  including a U-shaped slot  810  is used to attach the vertical rod  802  to the deflection rod system  800  as will be described in greater detail below. 
     Referring now to  FIGS. 56A and 56B , the connector  804  in this embodiment is shown as including a cylindrical body  806  having an internal cylindrical bore  808 , a U-shaped slot  810  and a lock tab  812 . The deflection rod system  800  in this embodiment includes a deflection rod  814  (preferably made of Nitinol, Niti or other super elastic material) having an outer shell  815  (preferably made of PEEK or other comparable polymer) and a spherical ball or joint  816 . The connector  804  includes a socket chamber  818  which is formed within the U-shaped slot  810  for receiving the spherical ball or joint  816  of the deflection rod system  800 . Once the spherical ball or joint  816  of the deflection rod system  800  is positioned within the socket chamber  818 , the exterior panel  820  of the lock tab  812  can be moved from its open, undeployed configuration (as shown in  FIG. 56A ) to its closed, deployed configuration (as shown in  FIG. 56B ), thereby closing the opening of the U-shaped slot  810  around the spherical ball or joint  816  of the deflection rod system  800  to secure the deflection rod system  800  to the connector  804 . The specific mechanism employed to move the exterior panel  820  of the lock tab  812  in this embodiment of the invention is illustrated in  FIG. 59 , which is described in greater detail below. In the deployed configuration of the connector  804 , the deflection rod system  800  is pivotally engaged to the connector  804  within the socket chamber  818  while the deflection rod shaft  814  extends away from the connector  804 . Consequently, the vertical rod  802  is allowed to rotate and/or have tilting and/or swiveling movements about a center that corresponds with the center of the spherical joint  816 . 
       FIG. 57  illustrates the vertical rod  802  used in this embodiment of the invention. The vertical rod  802  includes a vertical rod shaft  822 , a threaded band  824 , and an end cap  826  having a cavity  828  for accepting the lock tab  812  of the connector  804 . In this embodiment, the threaded band  824  and the end cap  826  are both located adjacent to the first end  830  of the vertical rod shaft  822 . The diameter of the threaded band  824  can be greater than the diameter of the vertical rod shaft  822  and the end cap  826 . In an embodiment, the vertical rod  802  may not include an end cap  826  at all, in which case the threaded band  824  will include a cavity for accepting the lock tab  814  of the connector  804 . 
       FIG. 58  provides a detailed illustration of the lock tab  812  used in this embodiment of the invention. The lock tab  812  includes the exterior panel  820 , a cylindrical platform  832  and a knob  834 . In this embodiment, the exterior panel  820  can include a convex outer surface  836  and a concave inner surface  838 . The cylindrical platform  832  is located along the inner surface  838  of the exterior panel  820 , the top surface  840  of the cylindrical platform  832  being parallel to the top surface  842  of the exterior panel  820 . The knob  834  is centrally located along the top surface  842  of the cylindrical platform  832 . In use within the connector  804 , the knob  834  can be used to fasten the lock tab  812  to the vertical rod  802 , whereby the inner surface  838  of the exterior panel  820  and the knob  834  both conform to the shape of the end cap  826  of the vertical rod  802  as shown in  FIG. 59 . In order to secure the knob  834  to the vertical rod  802  the knob  834  includes a cylindrical base  844  having a bevel-shaped collar  846  and a U-shaped slit  848 . As the knob  834  is inserted into the cavity  828  within the end cap  826  of the vertical rod  802 , the U-shaped slit  848  allows the ends  850  of the knob  834  to pinch in until the collar  846  extends past the top of the end cap  826  of the hollow vertical rod  802 . Once the collar  846  extends past the top of the end cap  826 , the collar  846  catches under lip  84  and returns to its original unpinched configuration, thereby securing the vertical rod  802  to the lock tab  812  (as shown in  FIG. 59 ). 
     Referring to  FIG. 59 , a cross-sectional view of the deflection rod system  800  and the vertical rod  802  within the connector  804  can be seen. The connector  804  has an internal cylindrical bore  808  for accepting the vertical rod  802  which is positioned substantially parallel to the longitudinal axis of the cylindrical body  806 . The interior surface of the cylindrical body  806  includes threads  852  for engaging the threaded band  824  of the vertical rod  802 . In this embodiment, the vertical rod  802  can be screwed into the cylindrical body  806  until the end cap  826  of the vertical rod  802  is placed in sliding engagement with the lock tab  812  knob  834 . Engagement of the vertical rod  802  to the lock tab  812  is accomplished, as set forth above, by inserting the knob  834  into the cavity  828  of the end cap  826  of the vertical rod  802  until the collar  846  of the knob  834  extends past the lip  847  of the end cap  826 , whereby the collar  846  of the knob  834  secures the vertical rod  802  to the lock tab  812 . In this configuration, the end cap  826  of the vertical rod  802  is free to rotate around the knob  834  of the lock tab  812  while the vertical rod  802  remains engaged to the lock tab  812 . Once the vertical rod  802  is placed in engagement with the lock tab  812 , the lock tab  812  can be moved up and down by way of threaded movement of the vertical rod  802  within the cylindrical body  806  of the connector  804 . In the deployed configuration of the connector  804 , the spherical ball or joint  816  of the deflection rod system  800  is inserted into the U-shaped slot  810  of the connector. Once the ball  816  of the deflection rod system  800  is positioned therein, the exterior panel  820  and the locking tab  812  can be moved down to block the opening of the U-shaped slot  810  of the connector  804 . In an embodiment, the lower inner surface  854  of the lock tab  812  can be concave and rounded to engage the spherical ball or joint  816  of the deflection rod system  800 . 
       FIGS. 60-64  illustrate another embodiment of the deflection rod system  900 , the vertical rod  902  and the connector  904  used within the dynamic stabilization system  700 . As shown in  FIG. 60 , the deflection rod system  900  used in this embodiment includes a deflection rod  906  having an outer shell  907 , the deflection rod  900  further including spool-shaped end caps  908  attached thereto, having circumferential retaining ridges  915 , attached to the ends of the end cap  908 . The end cap  908  can be screwed, glued, force fit, fused and/or laser welded onto the deflection rod  906 . In this embodiment, the spool-shaped cap  908  is not connected to the shell  907 . Instead, the shell  907  extends along the rod  906  and is short of the end cap  908 . As with other embodiments, the deflection rod  906  can be comprised of a super elastic material and the shell  907  can be comprised of a polymer such as PEEK. The shell  907  protects the rod  906  and adds rigidity to the deflection rod system  900 , and the rod  906  includes the deflection and recovery properties of a super elastic material. One of ordinary skill in the art can appreciate that other embodiments of the deflection rod system  900 , such as the ones illustrated in  FIGS. 68-71  or any other embodiments described herein, can be used in this embodiment of the dynamic stabilization system  700  without deviating from the scope of this invention. 
       FIG. 60  illustrates the connector  904  used in an embodiment of the invention. The connector  904  can be seen as including a C-shaped slot  910  for accepting the spool-shaped end cap  908  of the deflection rod system  900  and a sliding tab  912  which can close the opening of the C-shaped slot  910  to secure the spool-shaped end cap  908  of the deflection rod system  900  to the connector  904 . 
     Referring now to  FIG. 61 , a detailed illustration of this embodiment of the connector  904  is provided. The connector  904  can be seen as including the C-shaped slot  910  including two channels  914  adjacent to the side surfaces  916  of the connector  904 . The channels  914  allow the C-shaped slot  910  to conform to the shape of the end cap  908  of the deflection rod system  900  (as shown in  FIG. 60 ) and receives the circumferential retaining ridges  915  of the end cap  908 . This configuration defines the movement of the deflection rod  900  within the connector  904 . The connector  904  further includes L-shaped tab restraints  918  having a pair of grooves  920  along the inner surface of the tab restraints  918  as well as a groove  922  along the lower inner surface of the C-shaped slot  910 . The L-shaped tab restraints  918  and various grooves  920 ,  922  facilitate securing the sliding tab  912  to the connector  904  as will be described in greater detail below. 
     Referring now to  FIG. 62A  and  FIG. 62B , the embodiment of the sliding tab  912  shown in  FIG. 60  is illustrated in greater detail. The sliding tab  912  of this embodiment includes a first end  924  and a second end  926 . The sliding tab  912  further including a U-shaped slot  928  at end  924 , side knobs  930 , a bottom lip  932  at end  926  and a rear restraint  934 . The U-shaped slot  928 , located adjacent to the first end  924  of the sliding tab  912 , is positioned parallel to the longitudinal axis of the sliding tab  912 . The U-shaped slot  928  allows the first end  924  of the sliding tab  912  to pinch together within the L-shaped tab restraints  918  of the connector  904  (shown in  FIG. 61 ) as the sliding tab  912  is being placed in its deployed position. The side knobs  930  are located on the side surfaces  936  of the sliding tab  912  and conform to the grooves  920  along the inner surface of the tab restraints  918  of the connector  904  (shown in  FIG. 61 ). The bottom lip  932 , located adjacent to the second end  924  of the sliding tab  912 , conforms to and can be received in the groove  922  along the lower inner surface of the C-shaped slot  910  of the connector  904  (shown in  FIG. 61 ). Referring to  FIG. 62B , the back surface  938  of the sliding tab  912  can be seen as including a curved section  940  which can be configured to conform to the cylindrical shape of the spool-shaped end cap  908 . The back surface  938  of the sliding tab  912  can also include the rear restraint  934 . In this embodiment, the rear restraint  934  can be inserted into a slot  948  within the vertical rod  902  (shown in  FIG. 64 ) to position the vertical rod  902  relative to the connector  904  for deployment into a patient. The side knobs  930  and the bottom lip  932  also facilitate securing the sliding tab  912  to the connector  904  (as shown in  FIG. 63 ). 
       FIG. 63  illustrates the connector  904  in its deployed configuration. As shown, the deflection rod system  900  is secured to the connector  904  within the C-shaped slot  910  using the sliding tab  912 . In this configuration, the side knobs  930  are mated with the grooves  920  along the inner surface of the tab restraints  918  and the bottom lip  932  is mated with the groove  922  along the lower inner surface of the C-shaped slot  910 , thereby locking the sliding tab  912  into its deployed position within the connector  904  and locking the connector  904  about the spool-shaped end cap  904 . Accordingly, the vertical rod can rotate about the end cap  904  and thus rotate about the longitudinal axis of the torsion rod system  900 . 
     As shown in  FIG. 64 , the vertical rod  902  used in this embodiment of the invention includes a vertical rod shaft  944 , a first slot  946  for accepting the connector  904  and a second slot  948  for accepting the rear restraint  934  of the sliding tab  912 . The vertical rod  902  also includes an aperture  950  for accepting a screw, rivet or pin. In this embodiment, the back of the connector  904  can be shaped to conform to the shape of the vertical rod  902 . Accordingly, the vertical rod  902  can be mated with the connector  904  as shown in  FIG. 60 , and a screw, rivet or pin can be inserted through the aperture  950  of the vertical rod  902  into the connector  904  to secure the vertical rod  902  to the connector  904  and/or allow the vertical rod  902  to pivot about the screw, rivet or pin (see arrows  905 ) and relative to the horizontal rod  900 . The rear restraint  934  can be held in the slot  948  prior to the sliding tab  912  being lockingly deployed to capture the spool-shaped end cap  918  in the C-shaped slot  910 . 
       FIGS. 65-67  illustrate yet another embodiment of the deflection rod system  1000 , the vertical rod  1002  and the connector  1004  which can be used as a part of the dynamic stabilization system  700 . Referring now to  FIG. 65 , the deflection rod system  1000  can be seen as including a deflection rod  1006  having spool-shaped end caps  1008  attached to the ends of the shaft  1006  and shell  1007  similar to the embodiment depicted in  FIG. 60 . It is noted that one of ordinary skill in the art can appreciate that other embodiments of the deflection rod system  1000 , such as the ones illustrated in  FIGS. 68-71  or any other embodiments described herein, can be used in this embodiment of the dynamic stabilization system  700  without deviating from the scope of this invention. 
       FIG. 66  illustrates the connector  1004  of this embodiment of the invention. The connector  1004  can be seen as having a U-shaped slot  1010  on the first end  1012  of the connector  1004 , and a clamp, generally numbered  1014 , on the second end  1016  of the connector  1004 . The U-shaped slot  1010  can be configured to accept the vertical rod  1002 . In an embodiment, the connector  1004  includes apertures  1018 ,  1020  along the sides of the U-shaped slot  1010  for accepting a pin or screw  1022 . Once an aperture  1036  ( FIG. 67 ) of the vertical rod  1002  is placed within the U-shaped slot  1010 , the pin or screw  1022  can be inserted into the apertures  1018 ,  1020  of the connector  1004  as well as the vertical rod  1002  to either fixedly or pivotally secure the vertical rod  1002  to the connector  1004 . The pin or screw  1022  can be fused, glued, screwed, force fit and/or laser welded to the connector  1004 . 
     The clamp  1014  includes a C-shaped arm  1024  as well as a C-shaped locking paw  1026  that is pivotally attached to the connector  1004  using a pivot pin  1028 . The clamp  1014  also includes a clamp set screw  1030  which can adjust the position of the locking paw  1026 . In this embodiment, the end cap  1008  of the deflection rod  1000  can be secured to the connector  1004  between the C-shaped arm  1024  and the locking paw  1026  in the closed configuration of the clamp  1014  as shown in  FIG. 65  and held in place by set screw  1030 . Accordingly, the vertical rod can pivot about the deflection rod  1006  with the end cap  1008  retained in the clamp  1014 . 
     Referring now to  FIG. 67 , the vertical rod  1002  used in this embodiment of the invention can be seen as including a cylindrical shaft  1032 , a head  1034  having an aperture  1036  for accepting a pin or screw, and a spacer  1038  located between the head  1034  and the shaft  1032 . In this embodiment, the head  1034  of the vertical rod  1002  conforms to the U-shaped slot  1010  of the connector  1004 . 
     Alternate Embodiments of the Deflection Rod System and the First Horizontal Rod of the Invention 
       FIGS. 68-71  illustrate another embodiment of deflection rod system  1100  which can be used within the embodiments of the dynamic stabilization systems  700  described herein. The deflection rod system  1100  generally includes a deflection rod  1108  and two end caps  1104 . The end cap  1104  can be, for example, spool-shaped or spherically-shaped as illustrated with respect to other embodiments. The deflection rod system  1100  can also include an outer shell  1106 . In an embodiment, the deflection rod  1108  is cylindrical and made of a super elastic material, preferably Nitinol (NiTi). The diameter of the deflection rod  1108  is constant in this embodiment. In this embodiment, the outer shell  1106  of the deflection rod system  1100  is made of a biocompatible material or polymer, preferably PEEK, which is less elastic than the deflection rod  1108 . In this embodiment, the deflection rod shell  1106  includes a hollow tube which is generally tapered. The tube increases in diameter from the ends  1118  of the shell  1106  to the central portion  1110  of the outer shell  1106 . A channel  1112  can be provided at the central portion of the shell  1106  to facilitate the retention of the deflection rod system  1100  in a mount on a horizontal rod such as, for example, mount  714  on horizontal rod  708  in  FIG. 45 . Instead of a channel  1112 , a ring-shaped plateau or land can be defined having the largest diameter of the shell  1106  ( FIG. 70 ). Either the channel  1112  or the plateau can be received in the mount  714  of the horizontal rod system as seen in  FIG. 48 . In an embodiment, the end caps  1104  can be made of titanium, stainless steel, a biocompatible polymer such as PEEK or another biocompatible material. In this embodiment, the end caps  1104  are spool shaped or cylindrical shaped and include a central channel  1114 . 
     The deflection rod  1108  can be inserted into the outer shell  1106  of the deflection rod system  1100  so that the ends  1116  of the deflection rod  1108  extend past from the ends  1118  of the outer shell  1106 . The end caps  1104  can then be attached to the end  1116  of the deflection rod  1108 . The purpose of the deflection rod shell  1106  is to protect the deflection rod  1108 , which is made of the super elastic material and to support and restrict the motion of the rod  1108 . The outer shell  1106  also serves to reduce the strain on the deflection rod  1108  as force is applied to the ends  1116  of the deflection rod  1108 . As increased strain is placed on the ends  1116  of the deflection rod  1108 , and spread along the entire length of the deflection rod  1108 , the deflection rod shell  1106  can resist such strain along the entire length of the shell  1106 . The outer shell  1106  of the deflection rod system  1100  helps to limit the maximum amount of deflection allowed by the deflection rod system  1100  as well as support and protect the deflection rod  1108 . 
       FIGS. 70 and 71  illustrate other embodiments of the deflection rod system  1100 . Referring first to  FIG. 70 , this embodiment of the deflection rod system  1100  is similar to the deflection rod system  1100  embodied in  FIG. 68 . However, in this embodiment, the central portion of the deflection rod shell  1106  includes a central ring or plateau  1120  as opposed to a channel. Referring now to  FIG. 71 , this embodiment of the deflection rod system  1100  includes a deflection rod shaft  1122  having a constant diameter and two end caps  1124  also having constant diameters. As can be seen in  FIG. 71 , the diameter of the deflection rod shaft  1122  is larger than the diameter of the end caps  1124 . It is noted that as with the deflection rod system  1100  illustrated in  FIGS. 68 and 69 , the embodiments of the deflection rod systems illustrated in  FIGS. 70-71  include a deflection rod or core  1108  and a deflection rod shell  1106  as described above. The embodiments illustrated in  FIGS. 68-71  are not intended to be limiting and it is envisioned that the deflection rod system  1100  may include other embodiments which would be evident to one skilled in the art without deviating from the scope of the invention. 
       FIGS. 72A-73C  illustrate alternative embodiments of the first horizontal rod  708 . Referring now to  FIG. 72A , an embodiment of the first horizontal rod  708  is shown as including a mount  714 , a pair of guide or deflection restraining rings  1200  and a pair of grooves  1202  proximal to and outboard of the guide rings  1200 . In this embodiment, the deflection rod system  712  is secured to the first horizontal rod  708  within the mount  714 . The deflection rod system  712  is further contained within the guide rings  1200  proximal to the ends of the deflection rod system  712 . The guide rings  1200  can be used to limit the amount of deflection of the deflection rod system  712  in use as well as to prevent the deflection rod system  712  from becoming overextended during use. In this embodiment, the guide rings  1200  are elliptical rings wherein the vertical diameters of the guide rings  1200  are greater than the horizontal diameters of the guide rings ( FIG. 72C ). Again, horizontal referring to a horizontal orientation with respect to a patient that is standing and vertical referring to a vertical orientation with respect to a patient that is standing. The configuration of the guide ring  1200  allows the deflection rod system  712  to have a greater amount of vertical deflection than horizontal deflection. It is envisioned that the guide rings  1200  can have other configurations and still fall within the scope of this invention. 
     The first horizontal rod  708  also includes the grooves  1202  which can be mated with corresponding knobs  1204  located on the end caps  1206  of a vertical rods  716  to keep the ends caps  1206  and/or the vertical rods  716  aligned during deployment into the patient. Alternatively, such initial alignment technique can be dispensed with. In this embodiment, the vertical rod  716  includes an end cap  1206  and a main vertical shaft  1208  wherein the main vertical shaft  1208  can be screwed into the end cap  1206 . It is to be understood that the horizontal system can first be inserted into a patient without the main vertical shaft  1208  being attached (as shown in  FIG. 72B ). Once the horizontal system has successfully been inserted, the main vertical shafts  1208  can be attached to the end caps  1206 , wherein the grooves  1202  and the knobs  1204  can act to align and steady the end caps  1206  as the main vertical shafts  1208  are inserted into the end caps  1206  (as shown in  FIG. 72C ). 
     Referring now to  FIGS. 73A-73C , another embodiment of the first horizontal rod is illustrated. As can be seen in  FIGS. 73A and 73B , the first horizontal rod  708  of this embodiments includes a deflection rod collar or shield  1210  that wraps around the deflection rod system  1100 . The deflection rod shield  1210  is preferably stiff and rigid (and made of titanium, for example). The deflection rod shield  1210  can be used to protect the deflection rod  712  from damage during use. The deflection rod system  1100  includes a rod  1108  and an outer shell  1106  as shown for the deflection rod system  1100  in  FIG. 69 . The deflection rod shield  1210  can also be used to limit the amount of deflection of the deflection rod system  1100  as well as prevent the deflection rod system  1100  from becoming overextended during use. Referring now to  FIG. 73C , the inner surface  1212  of the deflection rod shield  1210  can be seen as being tapered wherein the diameter of the inner surface  1212  of the deflection rod shield  1210  is greater at the ends  1214 ,  1216  than at the center  1218  of the deflection rod shield  1210 . In this configuration, the surface of the deflection rod system  1100  can touch the inner surface  1212  of the deflection rod shield  1210  during use. Accordingly, the deflection rod shell  1210  can limit the movement of the deflection rod system  1100  and assist in spreading the load and strain on the deflection rod system  1100  along the entire length of the deflection rod system  1100 . Also in this embodiment, the first horizontal rod  708  includes a cavity  1220  to encompass the deflection rod system  1100  within the deflection rod shield  1210  to give the first horizontal rod  708  a smaller profile when implanted into a patient. It is envisioned that the deflection rod system  1100  can be mounted to any other type of horizontal rod which would be obvious to one skilled in the art without deviating from the scope of the invention. 
     Alternative Embodiments for Connections Used to Mate the Vertical Rod System to the Second Horizontal System 
       FIGS. 74-79B  illustrate embodiments of a second horizontal rod  710  which can be used within the dynamic stabilization system  700  described above. Referring now to  FIG. 74 , the horizontal rod  710  can generally be seen as including a main body  1300  and two cylindrical shafts  1302  extending away from each side of the main body  1300 . The main body  1300  includes cylindrical slots  1304  adjacent to the ends  1306 ,  1308  of the main body  1300  and sockets  1310  for accepting a cam  1312 . In this embodiment, the cylindrical slots  1304  are about perpendicular to the cylindrical shafts  1302 . The two cylindrical shafts  1302  can be connected to the anchor system  702  while the cylindrical slots  1304  can be used to accept and secure the vertical rods  716  to the second horizontal rod  710  as shown in  FIG. 48 . 
     Referring now to  FIG. 75 , the cylindrical slot  1304  for accepting a vertical rod  716  and the socket  1310  for accepting a cam  1312  can be seen in greater detail. As shown in  FIG. 75 , the cylindrical slot  1304  is located along the top surface  1314  of the main body  1300  and extends about perpendicular to the longitudinal axis of the second horizontal rod  710 . In this embodiment, a slit  1316  is located underneath the cylindrical slot  1304  in order to allow the sides of the cylindrical slot  1304  to pinch together around a vertical rod  716  in the deployed configuration of the second horizontal rod  710 . 
     Located adjacent to the cylindrical slot  1304  is the socket  1310  for accepting a cam  1312 . One purpose of the cam  1312  is to provide a mechanical means to pinch the sides of the cylindrical slot  1304  together in order to secure the vertical rods  716  to the second horizontal rod  710 . The socket  1310  of this embodiment includes a flat front face  1318 , a rounded back face  1320 , and two rounded side faces  1322 ,  1324 . The front face  1318  includes a groove  1328  while the back face  1320  includes a channel  1326 , both of which can be used to help keep the cam  1312  secured within the second horizontal rod  710 . The front and back faces  1318 ,  1320  are also elevated from the side faces  1322 ,  1324 . In this configuration, a cam  1312  having a first side tab  1330  and a second side tab  1332  (as shown in  FIGS. 77A ,  77 B) can be inserted into the socket  1310  wherein the side tabs  1330 ,  1332  are initially placed adjacent to the side faces  1322 ,  1324  of the second horizontal rod  710 . As a vertical rod  716  is placed within the cylindrical slot  1304 , the cam  1312  can be twisted in order to position a first side tab  1332  within the groove  1328  of the front face  1318  and a second side tab  1330  within the channel  1326  of the back face  1320 . In this configuration, the first side tab  1332  and the second side tab  1334  of the cam  1312  secure the cam  1312  to the second horizontal rod  710  while also causing the sides of the cylindrical slot  1304  to pinch together, thereby securing the vertical rod  716  to the second horizontal rod  710 . In an embodiment, the cam  1312  can also include a tapered ridge  1334  (as shown in  FIGS. 77A ,  77 B) which further helps to pinch the sides of the cylindrical slot  1204  together around the vertical rod  716 . 
     Referring now to  FIG. 76 , the socket  1310  can also include an aperture  1340 , the aperture  1340  extending from the floor  1336  of the socket  1310  to the bottom surface  1342  of the second horizontal rod  710 . The aperture  1340  can include a first section  1344  and a second section  1346 . In this embodiment, the diameter of the first section  1344  of the aperture  1340  is smaller than the diameter of the second section  1346  of the aperture  1340 . The height and diameter of the first section  1344  of the aperture  1340  can be designed to conform to the shape of a fastener located on the bottom of a cam which can be inserted therein. For example, the cam  1312  shown in  FIG. 77A  includes fasteners  1348  located on the bottom of the cam  1312 . The cam fasteners  1348  include ends  1350  which extend away from the main body  1352  of the fasteners  1348 . In use, as the fasteners  1348  are inserted into the aperture  1340  of the socket  1310 , the fasteners  1348  pinch in until the ends  1350  of the fasteners  1348  extend past the first section  1344  of the aperture  1340 . Once the ends  1350  of the fasteners  1348  extend past the first section  1344  of the aperture  1340 , the fasteners  1348  return to their relaxed configurations, and engage lip  1347 , wherein the main body  1352  of the fasteners  1348  engage the second horizontal rod  710  along the first section  1344  of the aperture  1340  while the ends  1350  of the fasteners  1348  and engage lip  1347  help prevent the cam  1312  from becoming disengaged from the second horizontal rod  710 . 
       FIGS. 78-79C  illustrate an alternative embodiment of a cam  1354 . Referring now to  FIG. 78 , the cam  1354  of this embodiment can be seen as including a top section  1356 , a cylindrical body  1358  and fasteners  1360  on the bottom of the cam  1354 . The top section  1356  further includes a restraining tab  1362  and a side tab  1364  located between two grooves  1366 ,  1368 .  FIG. 79A  illustrates cam  1354  which has been force fit in the socket  1310  of the second horizontal rod  710  in its undeployed configuration. The cam  1354  is secured to the second horizontal rod  710  through the use of the fasteners  1360  in the same manner as set forth above for cam  1312 .  FIG. 79B  illustrates cam  1354  within the second horizontal rod  710  in its deployed configuration. In this configuration, once the vertical rod  716  is placed in the cylindrical slot  1304  of the second horizontal rod  710 , the cam  1354  can be rotated until the side tab  1364  of the cam  1354  is aligned with the groove  1328  of the front face  1318  of the socket  1310  and the restraining tab  1362  of the cam  1354  is placed within an indentation  1370  of the front face  1318  of the socket  1310 . The side tab  1362  causes the sides of the cylindrical slot  1304  to pinch together, thereby securing the vertical rod  716  to the second horizontal rod  710 . 
       FIGS. 80-85  illustrate an alternative embodiment of the second horizontal rod which can be used within the dynamic stabilization system  700  described above. Referring now to  FIG. 80 , a second horizontal rod  1400  (previously shown in  FIG. 74  as second horizontal rod  710 ) includes a connector  1402  to secure the second horizontal rod  1400  to the vertical rod  716 . The connector  1402  of this embodiment includes a main body  1404  and a rotating link  1406 .  FIGS. 81 and 82  illustrate the individual components included in this embodiment of the second horizontal rod  1400  as well as the connector  1402 . 
     Referring now to  FIG. 81 , the main body  1404  of the connector  1402  can be seen as including a C-shaped slot  1408  for housing the rotating link  1406  along the front face  1410  of the main body  1404 . The main body  1404  also includes a first aperture  1412  and a second aperture  1416 . The first aperture  1412  is located along the back face  1414  of the main body  1404  and is configured to accept the vertical rod  716 . The second aperture  1416  is located at the top  1418  of the main body  1404  and can be threaded to accept a threaded fastening or set screw  1420 . 
     Referring now to  FIG. 83 , the rotating link  1406  can be seen as including a saddle-shaped groove  1422  on the top surface of the rotating link  1446  which is positioned substantially perpendicular to the longitudinal axis of the rotating link  1406 . The saddle-shaped groove  1422  includes an aperture  1426  that extends from the top  1424  to the bottom surface  1428  of the rotating link  1406 . Finally, the rotating link  1406  includes an internal cylindrical bore  1430  for accepting the second horizontal rod  1400  which is positioned substantially parallel to the longitudinal axis of the rotating link  1406 . 
     Referring back to  FIG. 80 , this embodiment of the second horizontal rod  1400  can be seen in its deployed configuration. In this configuration, the second horizontal rod  1400  is inserted into the cylindrical bore  1430  of the rotating link  1306 . In this embodiment, the second horizontal rod  1400  can include a dowel pin  1432  (as shown in  FIG. 82 ) that extends through the aperture  1426  along the bottom surface  1428  of the rotating link  1406  (as shown in  FIG. 83 ) when the second horizontal rod  1400  is inserted into the rotating link  1406 . One purpose of the dowel pin  1432  is to keep the rotating link  1306  positioned on the rod  1400  with restricted motion longitudinally along the rod  1400  and circumferential about the rod  1400  as will be described in greater detail below. It can further be seen in  FIG. 80  that the rotating link  1406  is placed within the C-shaped slot  1408  of the main body  1404 , with the vertical rod  716  being positioned within the saddle-shaped groove  1422  of the rotating link  1406 . In this embodiment, the vertical rod  716  can be inserted into the aperture  1412  located along the back face  1414  of the main body  1404  perpendicular to the second horizontal rod  1400  and the rotating link  1406 . The extent that the vertical rod  716  is inserted into the aperture  1412  can be varied to accommodate the specific vertebrae being affected. The fastening screw  1420  is used to secure the vertical rod  716  and the rotating link  1406  to the main body  1404 . 
     As shown in  FIGS. 82 ,  84  and  85 , the second horizontal rod  1400  can also include a section  1434  having threads or grooves  1438  to engage threads or grooves  1436  on a vertical rod  716 . In this embodiment, the threads or grooves  1438  on the section  1434  engage a recessed, threaded or grooved section  1436  of the vertical rod  716  on one side of the section  1434 , while a dowel pin  1432  extends on the opposing side, the dowel pin  1432  extending past the aperture  1426  along the bottom surface  1428  of the rotating link  1406 . In this configuration, the vertical rod  716  is allowed to have limited vertical movement within the main body  1404  of the connector  1402 . The dowel pin  1432  extends through the aperture  1426  of the rotating link  1406 , thereby limiting the degrees of freedom of motion and with the help of set screw  1420 , fix the position of the horizontal rod  1400  relative to the vertical rod  716 . An alternative embodiment of the connector can eliminate one or any combination of two or more of the rotating link  1406 , the dowel pin  1432 , the threads or grooves  1438 , and the threaded or grooved section  1436 . It is noted that the second horizontal rod  1400  can be a straight rod having a constant diameter (as shown in  FIG. 84 ) which is made of a stiff and rigid material (titanium, for example). It is also noted that other types of connectors can also be used which would be obvious to one skilled in the art without deviating from the scope of the invention. 
     Method of Implantation and Revised Implantation: 
     A method of implantation of the system in the spine of the human patient is as follows. First the vertebral levels that are to receive the system are identified. Then the anchor systems are implanted, generally two anchor systems for each level. The anchor systems can be implanted using a cannula and under guidance imaging such as x-ray imaging. Alternatively, the anchor system can be implanted using traditional spinal surgery techniques. Then the horizontal rods are inserted and secured to the anchor systems. The horizontal rods can be inserted laterally through a cannula or with an incision and the use of, for example, a lead-in cone. Alternatively, the horizontal rods can be inserted using traditional techniques when the anchor systems are implanted. Thereafter, the vertical rods can be connected to or pivoted, rotated or placed into communication with and secured to the appropriate horizontal rod. 
     Should a dynamic stabilization system such as system  100  be initially implanted and then should there be a desire to make the system more rigid or to accomplish a fusion, the system  100  can be revised by removing the horizontal rod  104  that includes the deflection rods or loading rods and replace it with a horizontal rod  106  which has the vertical rod mounts ( FIG. 34 ) and is thus substantially more rigid. Thus a revision to a fusion configuration can be accomplished with minimal trauma to the bone and tissue structures of the spine. 
     Materials of Embodiments of the Invention 
     In addition to Nitinol or nickel-titanium (NiTi) other super elastic materials include copper-zinc-aluminum and copper-aluminum-nickel. However for biocompatibility the nickel-titanium is the preferred material. 
     As desired, the implant can be made of titanium or stainless steel. Other suitable material includes by way of example only polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK), and polyetheretherketoneketone (PEEKK). Still, more specifically, the material can be PEEK 450G, which is an unfilled PEEK approved for medical implantation available from Victrex of Lancashire, Great Britain. (Victrex is located at www.matweb.com or see Boedeker www.boedeker.com). Other sources of this material include Gharda located in Panoli, India (www.ghardapolymers.com). 
     As will be appreciated by those of skill in the art, other suitable similarly biocompatible thermoplastic or thermoplastic polycondensate materials that resist fatigue, have good memory, are flexible, and/or deflectable have very low moisture absorption, and good wear and/or abrasion resistance, can be used without departing from the scope of the invention. 
     Reference to appropriate polymers that can be used in the spacer can be made to the following documents. These documents include: PCT Publication WO 02/02158 A1, dated Jan. 10, 2002, entitled “Bio-Compatible Polymeric Materials;” PCT Publication WO 02/00275 A1, dated Jan. 3, 2002, entitled “Bio-Compatible Polymeric Materials;” and PCT Publication WO 02/00270 A1, dated Jan. 3, 2002, entitled “Bio-Compatible Polymeric Materials.” 
     The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.