Abstract:
This invention relates to interconnection assemblies for use with spinal fixation systems to treat spinal defects. The interconnection assemblies can include various spinal rod connecting members and interconnecting elements to secure the spinal rod connecting members to each other in variable orientations and lengths. The interconnection assemblies can be adjusted to minimize interference with the spinal column, bony processes, and associated neural, muscular, and ligament components of the spine all the while exhibiting a low profile. The interconnecting elements and related components can be provided as a completely assembled unit that does not inadvertently become disassembled prior to or during implantation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of co-pending U.S. patent application Ser. No. 10/695,067 filed on Oct. 28, 2003, which claims the benefit of U.S. Provisional Application Ser. No. 60/421,701 filed on Oct. 28, 2002, the contents of each of these applications hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     In general, the present invention relates to a system and components for correcting spinal defects. More specifically, the present invention is directed to spinal fixation systems including spinal rods and spinal rod interconnecting assemblies to treat and correct spinal deformities. 
     Spinal fixation systems are implanted during a surgical procedure to treat a variety of problems. These treatments include correction of congenital spinal deformities, e.g., scoliosis, spondylolisthesis, kyphosis, lordosis, and arthropathy; repair of spinal injuries; and fusion of vertebrae to stabilize congenital conditions and/or alleviate chronic lower back pain. Several techniques and systems have been developed for correcting and stabilizing the spine and facilitating spinal fusion. 
     In one common system, a longitudinal member such as a bendable rod, or spinal rod, is disposed along the vertebral column and is fixed at selected points to various vertebra along the length of the column by any number of fixation elements. A variety of these vertebral fixation elements are known and include hooks and bone screws. These fixation elements are configured to engage and attach to specific portions of the vertebrae. Usually, the surgeon attaches a vertebral fixation element to the spine in an appropriate anatomical position and then attaches each vertebral fixation element to the spinal rod. In conjunction, the surgeon twists and/or realigns the spinal column and/or individual vertebra to provide the desired treatment for the spinal defect. Consequently, the spinal rods may be bent or orientated along the spinal column non-parallel to each other. 
     The spinal rods are typically connected together to provide a more rigid support and alignment system, much like a ladder with rungs running between the supports. The cross-connecting members should accommodate the different orientations of the spinal rods. Further, the connecting members should be able to bridge the gap between the spinal rods without interfering with the structures and nerves, e.g., the spinal cord and/or spinal processes associated with or adjacent to the spinal column. Additionally, the connecting member should rigidly and securely interconnect the spinal rods. Obviously, failure of the system and dislocation of the spinal rods and associated components can cause the patient great pain and require additional surgical procedures to correct. An adjustable yet rigid cross connector would facilitate treatment of spinal defects. 
     Any surgical operation, by nature, is a delicate procedure; operations proximate to the spinal column are even more delicate and demanding. In addition to the expected surgical procedures, the surgeon must force the spinal column and individual vertebra into alignment. During this procedure or immediately thereafter, the surgeon must position the fixation elements, assemble the spinal rod system, secure the spinal rod system to the vertebrae, and then tighten the connections in the entire system so no further movement occurs. Assembly of the spinal rod system can be very difficult, especially when the components are coated with body fluids. A more “user friendly” spinal fixation system that could be assembled quickly and reliably in the operating room would be a great benefit to both surgeons and their patients. 
     Thus, in light of the above-described problems, there is a continuing need for advancements in the relevant field, including improved spinal fixation assemblies, related components, and methods for treating spinal defects. The present invention is such an advancement and provides a wide variety of benefits and advantages. 
     SUMMARY OF THE INVENTION 
     In general, the present invention provides an assembly and apparatus for treatment of spinal defects. The assembly can comprise elongate members, such as spinal rods, bone fasteners to secure the elongate members to anatomical positions on individual vertebral bodies, and cross-connectors to interconnect the elongate members. 
     In one form, the present invention provides an interconnector assembly that includes a first spinal rod connector, a second spinal rod connector, and an interconnector element to secure the two spinal rod connectors at a selected orientation relative to each other. The first and second spinal rod connectors can be formed with curved shafts to provide increased clearance for the spinal column. The interconnecting element can include a body having an aperture and a threaded stud extending from the body. In one form, the element can be provided as an eyebolt with an opening through which a portion of one or both of the rod connectors can extend. A fastener can be secured to the stud extending from the body to securely lock the first and second elongate members in a desired orientation relative to each other. 
     In other forms, the present invention provides an interconnecting member that includes a first shaft, a second shaft, and a plurality of fasteners. The second shaft can carry a interconnection body on its terminal end. The interconnection body can include an opening to receive a portion of the first shaft to the first connector. One of the fasteners can be secured to the body to lock the first spinal rod connector in a desired orientation relative to the second spinal rod connector. 
     In yet another form, the present invention provides a multi-axial variable interconnector that can interconnect two spinal rod connecting members. In one embodiment, the multi-axial spinal rod connector includes a ball and socket joint. 
     In other forms, the interconnecting element can be provided as an eyebolt. The eyebolt includes a body having an opening therethrough, an upper surface, and a stud extending from that surface. Additionally, the upper surface can include a plurality of radial splines positioned about the studs. Alternatively, a washer with an upper surface having a plurality of radial splines can be provided around the internal stud. In either form, a second spinal rod connector member can include a lower surface having splines configured to matingly engage with the splines about the stud. A fastener can be secured to the stud to interdigitate the splines and, consequently, lock the first spinal rod connector in a desired orientation relative to the second spinal rod connector. 
     In still yet other forms, the present invention provides a spinal rod connector member that can secure a spinal rod within a hook. The hook can include a saddle or ridge portion within the curved or concave portion of the hook. The ridge or saddle portion can allow the spinal rod to seat within the hook at various orientations. Additionally, the spinal rod connector can include a threaded aperture and a fastener to be received therein to secure the spinal rod within the hook. 
     In still yet other forms, the present invention provides a pre-assembled interconnection assembly. The pre-assembled interconnection assembly maintains restricted movement of a first and second spinal rod connecting member. The restricted movement of the first and second spinal rod connecting members can be provided to allow extension of the interconnecting member and/or rotation of one spinal rod connecting member relative to a second spinal rod connecting member to secure non-parallel spinal rods. The restricted movement can also inhibit inadvertent disassembly of the interconnection assembly. Additionally, the connecting element can be configured to minimize or eliminate contact with various bone and neural structures, processes located posteriorly of the spinal column, while rigidly securing a pair of spinal rods extending longitudinally with the spinal column. 
     Further objects, features, forms, and advantages of the present invention will become apparent from the following descriptions and drawings contained herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded, perspective view of one embodiment of a spinal rod connector assembly in accordance with the present invention. 
         FIG. 2  is an exploded, perspective view of the connector assembly of  FIG. 1 , partly assembled. 
         FIG. 3  is a partial, top-plan view of the connector assembly of  FIG. 1 , partly assembled. 
         FIG. 4  is a perspective view of the connector assembly of  FIG. 1  pre-assembled in accordance with the present invention. 
         FIG. 5  is a cross-sectional view of the interconnecting element of the connector assembly of  FIG. 1 . 
         FIGS. 6A and 6B  are perspective views of alternative fasteners for use with the present invention. 
         FIG. 7  is a perspective view of a male connector member having a curved shaft in accordance with one embodiment of the present invention. 
         FIG. 8  is a perspective view of a female connector member having a curved shaft in accordance with one embodiment of the present invention. 
         FIG. 9  is a prospective view of a connector assembly having curved connector members in accordance with one embodiment of the present invention. 
         FIG. 10  is a perspective view of one embodiment of a female connector member having radial splines on a contacting surface in accordance with another embodiment of the present invention. 
         FIG. 11  is an exploded view of an interconnecting element including interlocking splines in accordance with another embodiment of the present invention. 
         FIG. 12  is a perspective view of a connector assembly including the female connector of  FIG. 10  and the interconnecting element of  FIG. 11  in accordance with the present invention. 
         FIG. 13  is an exploded view of another embodiment of a connector assembly having a variable angle interconnection in accordance with the present invention. 
         FIGS. 14 ,  14   a , and  14   b  illustrate an insert for use in the variable angle interconnection of  FIG. 13 . 
         FIG. 15  is a prospective view of the connector assembly of  FIG. 13 . 
         FIG. 16  is a cross-sectional view of a one-piece female connector member having an interconnecting element in accordance with the present invention. 
         FIG. 17  is prospective view of a connector assembly including the female connector member of  FIG. 16 . 
         FIG. 18  is prospective view of the connector assembly of  FIG. 17  in which the male and female connector members are orientated to position the interconnection element to allow for greater clearance for a spinal column. 
         FIG. 19  is yet another embodiment of a connector assembly having a variable angle interconnection in accordance with the present invention. 
         FIG. 20  is a prospective view of one embodiment of a friction insert for use in the present invention. 
         FIG. 21  is a prospective view of another embodiment of a friction insert for use in the present invention. 
         FIG. 22  is a cross-sectional view of a one-piece, female connector member and an interconnection element with a friction insert in accordance with the present invention. 
         FIG. 23  is an exploded view of a connector assembly having a click-lock connection in accordance with the present invention. 
         FIG. 24  is a cross-sectional view of a female connector member and the click-lock connection for use in the connector assembly of  FIG. 23 . 
         FIG. 25  is a perspective view of the connector assembly of  FIGS. 23 and 24  pre-assembled in accordance with the present invention. 
         FIGS. 26 and 27  are perspective views of an alternative embodiment of a unitary connector in accordance with the present invention. 
         FIGS. 28 and 29  are perspective views of the unitary interconnector illustrated in  FIGS. 26 and 27  secured to two spinal rods in accordance with the present invention. 
         FIG. 30  is a perspective view of an alternative unitary interconnecting member for securing a spinal rod in accordance with the present invention. 
         FIG. 31  is an illustration of a spinal column, two spinal rods secured to the spinal column, and a plurality of connector assemblies interconnecting the spinal rods in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated herein and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described systems, connection components, and methods, and any further applications of the principles of the invention as described herein, are contemplated as would normally occur to one skilled in the art to which the invention relates. 
       FIG. 1  is an exploded, perspective view of one embodiment of a connector assembly  10  in accordance with the present invention. Connector assembly  10  includes a male connector member  12 , a female connector member  14 , an interconnecting element  16 , and fastener  18 . Male connector member  12  includes a proximal end  22 , an opposite distal end  24 , and a shaft  26  therebetween. Proximal end  22  is provided to exhibit a round or oval cross-sectional profile. In a preferred embodiment, a protuberance or projection  28  extends from proximal end  22 . In the illustrated embodiment, projection  28  is provided as a cam or a lobe extending substantially orthogonal to a longitudinal axis or direction defined by shaft  26 . In alternative embodiments, projection  28  can be provided as a single or multiple finger(s) or spline(s) extending orthogonal or obliquely from shaft  26 . 
     Shaft  26  is provided as a cylindrical shaft, although it should be understood that shaft  26  can be provided in any configuration as desired. For example, shaft  26  can be provided with an oblong, rectangular, or triangular cross-section profile. Shaft  26  is illustrated as a substantially straight elongate member defining a longitudinal axis. In other embodiments, shaft  26  can be formed as an arched or curved shaft. Shaft  26  carries a rod connecting portion  32  on its distal end  24 . In any of the embodiments, shaft  26  can have a relative smooth exterior or, alternatively, its exterior can be roughened or knurled. 
     Shaft  26  terminates in rod connecting portion  32 , which is configured to engage a spinal rod or another elongate member, or a bone fastener. In a preferred embodiment, portion  32  is provided with a channel, recess or a hook, as desired, each which are adapted and configured to, at least partially, encircle a spinal rod. 
     Additionally, an aperture  34  or bore with internal threads can be tapped into male connecting member  12  to secure the member to a spinal rod or bone fastener. Aperture  34  extends into distal end  24  and preferably through shaft  76  or distal end  24  and into the interior of the hook. Aperture  34  can be formed into shaft  26  either orthogonal to or at an angle oblique to the longitudinal axis defined by shaft  26 . For example, aperture  34  can extend from an exterior surface of portion  32  to an interior surface proximal to the internal crook or hook of rod connecting portion  32 . A threaded fastener  36  can be threadedly received within aperture  34  to secure an included spinal rod to male connector member  12 . Examples of threaded fasteners are illustrated in U.S. Pat. Nos. 5,947,966 and 6,193,719, which are incorporated by reference in their entirety. Fastener  36  can include a blunt or concave tip. Alternatively, fastener  36  can include a tip that includes teeth and/or cutting edges to engage and indent a portion of an included spinal rod (not shown). 
     In a preferred embodiment, male connector member  12  is provided to have a preferred length selected for a particular application or use. In one embodiment, the preferred length measured along the longitudinal axis defined by shaft  26  of between about 20 mm and about 46 mm. 
     Interconnecting element  16  is illustrated as an eyebolt  44 . Eyebolt  44  includes an aperture  46  extending through a cylindrical or circular body  54 . Aperture  46  is provided to receive a portion of a shaft from a connecting member, such as connecting member  12  therethrough. In the illustrated embodiment, aperture  46  is configured as an oblong or oval opening. Preferably, aperture  46  is provided to matingly receive proximal end  22  including projection  28  of male connector member  12 . Interconnecting element  16  also includes a threaded stud  52  extending from body  54  substantially orthogonal to an axis  53  defined by aperture  46 . 
     In one embodiment, an interlocking member  56  is disposed between body  54  and threaded stud  52 . In the illustrated embodiment, interlocking member  56  includes a pair of flanges or shelves  58  and  60  extending diametrically opposite each other circumferentially about body  54 . Disposed between shelves  58  and  60  are a pair of opposing lands or truncated portions  62  and  64 , e.g., truncated when compared to shelf portions  58  or  60 . Truncated portions  62  and  64  can be formed substantially flush with the lateral sides of body  54 . The shelves  58  and  60  are provided as part of the swage locking mechanism to interengage interconnecting element  16  with female connector member  14 . 
     In another embodiment, threaded stud  52  extends directly from eyebolt  44  without the interlocking member  46  interposed therebetween. 
     Female connector member  14  is provided as the counterpart portion to male connector member  12 . Connector member  14  includes a proximal portion  78 , a distal spinal rod engaging portion  80 , and a shaft  82  therebetween. Shaft  82  can have a relative smooth exterior or, alternatively, its exterior can be roughened or knurled. Spinal rod engaging portion  80  can be provided substantially as described for rod connecting portion  32  of male connecting member  12 . In a preferred embodiment, portion  32  is provided with a channel, recess or a hook, as desired, each which are adapted and configured to, at least partially, encircle a spinal rod. Additionally, an aperture  85 —similar to aperture  34 —can be provided to extend either orthogonal or obliquely through member  14 . Preferably, aperture  85  allows a threaded fastener to engage the outer surface of a spinal rod seated within the hook or crook of rod engaging portion  80 . A fastener such as fastener  86  can be threadedly engaged through aperture  85  to secure a spinal rod in portion  80 . 
     Female connector member  14  includes a body  70  having an aperture  72  therethrough. In one form, body  70  is a substantially circular or oval configuration. In other forms, body  70  can be provided as desired, for example, cuboid or trapezoid. Aperture  72  is configured to slideably receive stud  52  therein. In preferred embodiments, aperture  72  is configured to have a larger internal diameter than the external diameter of the external threads on stud  52 . Consequently, in a preferred embodiment, the inside surface of aperture  72  is a smooth bore without any threads. In alternative embodiments, the internal surface of aperture  72  can be a threaded bore. In yet another embodiment, the internal surface of aperture  72  includes a pair of internal shelves  74  and  76 . Preferably shelves  74  and  76  are positioned diametrically opposite each other proximate to the lower surface  75  of body  70 . Shelves  74  and  76  are configured to interengage with interlocking member  56  and/or shelves  58  and  60  to secure female connector member  14  with interlocking member  56 . (For example, see  FIG. 3 .) In still yet other embodiments, aperture  72  can be provided as a smooth bore without either internal threads or internal shelves. Fastener  86  can be provided as described for fastener  36 . 
     In a preferred embodiment, female connector member  14  is provided to have a desired length suitably selected such that in conjunction with member  12 , two spinal rods can be secured together. In a preferred embodiment, connector member  14  is provided to have a length measured along the longitudinal axis defined by shaft  82  of between about 10 mm and about 65 mm. 
     Referring additionally to  FIGS. 2 through 5 , in use, proximal end  22  of male connector member  12  is received into and through aperture  46  until proximal end  22  and projection  28  extend from the opposite side of interconnection element  16 . When thus engaged, projection  28  is disposed on the opposite side of eyebolt  44  from distal end  24  of male connector member  12  as illustrated in  FIG. 2 . Rotation of male connector member  12  about its longitudinal axis allows projection  28  to contact the exterior surface of element  16  and be positioned adjacent lower surface  81  of eyebolt as illustrated in  FIG. 4 . It will be understood that to provide a variable angle connector, male connector member  12  can be rotated by an amount either less than or greater than about 180°. Next, female connector member  14  is positioned over stud  52  such that shelves  74  and  76  are proximal to truncated portions  62  and  64  as illustrated in  FIG. 3 . Rotation of female connector member  14  about stud  52  then engages shelves  74  and  76  with shelves  58  and  60 . This prevents connecting element  16  from being inadvertently disengaged or removed from stud  52  (without counter rotation). It will be understood that female connector member  14  can be adjusted at any angle in relation to male connector member  12  and/or interconnecting element  16  as desired to secure the spinal rods and facilitate treatment. Thereafter, fastener  18  can be engaged with stud  52  to secure male connector member  12  and female connector member  14  in the desired orientation as illustrated in  FIG. 5 . 
     In one embodiment, fastener  18  includes internal threads to engage the external threads on stud  52 . Additionally, fastener  18  can be provided as a setscrew with an internal tool engaging recess or imprint. In this embodiment, at least a portion of aperture  72  has a diameter sufficient to receive a portion or all of fastener  18  therein. This embodiment can minimize the profile of the assembled connector that extends posteriorly from the site of implantation. Additionally, the interior bore of aperture  72  can include a step or groove which can contact and bear against a corresponding (mating) portion on fastener  18 . Consequently, threading fastener  18  on stud  52  forces body  70  of the female connector member  14  onto eyebolt  44  such that lower surface  81  of body  70  contacts a portion of shaft  26  and/or projection  28 . Securing fastener  18  to stud  52  forces projection  28  to overhang a portion of body  70  and, consequently, inhibits withdrawal of shaft  26  of male connector member  12 . In other embodiments, fastener  18  includes a lip  67  that extends about its outer perimeter. When fastener  18  is threaded on stud  52 , lip  67  contacts the upper surface  83  of body  70  and similarly frictionally engages body  70  with shaft and/or projection  28 . In one form of this embodiment, fastener  18  can be provided as a cap having a round top. In either embodiment, male connector member  12  and interconnecting element  16  are locked or secured into a desired orientation relative to each other. 
     A variety of fasteners  18  can be used with the present invention. For example, one fastener, referred to as a “break off set screw”, can include a weakened section to allow a portion of fastener  18  to break or shear off upon application of sufficient torque. Examples of such break off set screws are described in U.S. Pat. No. 6,478,795 issued to Gournay et al. which is incorporated herein by reference. 
       FIG. 6A  provides another illustrative embodiment of a fastener  30  for use with the present invention. Fastener  30  includes an imprint configured to receive a driving tool. The imprint configuration can be provided as desired including a hex head imprint, a four-sided imprint, or a “torq” imprint sized as desired. 
       FIG. 6B  illustrates yet another embodiment of a fastener  31  for use with the present invention. Fastener  31  includes a head configured to be grasped by a driving tool such as a six-sided socket. Any of fasteners  18 ,  30 , and  31  can include internal threads or external threads to engage a stud extending from an eyebolt. 
     It should also be understood that connector assembly  10  can be provided by the manufacturer as an assembled unit—albeit loosely connected. When thus provided, the components cannot be inadvertently separated from each other. In one form, as illustrated in  FIG. 5 , the interior portion of stud  52  includes an interior bore  88  and fastener  18  includes a through bore. During manufacture, a dam (not shown) is inserted into interior bore  88  after attachment of fastener  18 . The dam can then splay the end  66  of interior bore  88  to prevent fastener  18  from backing off the threaded stud  52 . This prevents the assembly, including male connector member  12 , female connector member  14 , and interconnecting element  16 , from becoming inadvertently separated. 
       FIG. 7  is a perspective view of an alternative embodiment of a male connector member  94 . Member  94  is provided as has been described for male connector member  12 . However, male connector member  94  includes an arched or curved shaft  96 . Member  94  can be provided with an curved or arched side profile selected to eliminate contact between the resulting connector assembly and the spinal processes on the posterior of the spinal column. (See, for example,  FIG. 9 .) 
     Furthermore, connector member  94  includes a threaded aperture  95  that extends therethrough at an angle oblique to shaft  96 . 
       FIG. 8  is a perspective view of a female connector member  98 , similar to female connector member  14 . Connector member  98  includes a curved shaft  100 . Shaft  100  can be formed to have a curved or arched configuration that is selected to minimize or eliminate contact between the resulting connector assembly and the spinal processes on the posterior of the spinal column. Additionally, shaft  100  can be provided with substantially the same curvature as that of shaft  96 . 
     Female connector member  98  includes a body  103  having an aperture  102  therethrough. Aperture  102  is sized and configured to receive a stud such as stud  52  on eyebolt  44 . In the embodiment illustrated in  FIG. 7 , aperture  102  is provided as a substantially smooth bore without any threads or interlocking shelves or the like. Additionally, member  98  includes a threaded bore  114  provided as discussed above for aperture  95  in male connector member  94 . 
       FIG. 9  is a perspective view of a connector assembly  110 . Assembly  110  includes male connector member  94 , female connector member  98 , and an interconnecting element  16  secured with fastener  18 . In the illustrated embodiment, male connector member  94  and female connector member  98  are formed to exhibit the same or substantially similar arched profile along their respective shafts. Further, the overall length of assembly  110  measured along a longitudinal axis defined by the shaft of female connector member  98  can be variable by either sliding shaft  96  further through eyebolt  112  or sliding shaft  96  in the opposite direction to withdraw it from eyebolt  112 . Loosening fastener  18  allows shaft  96  of male connector member  94  to slide through the aperture  46  in interconnecting element  16 . Consequently, the overall length of connector assembly  110  can vary to allow the distal ends of the respective male and female connector members to grasp spinal rods positioned proximate to the transverse processes of the vertebra. Connector assembly  110  can have a depth measured along reference line  97  sufficient to minimize any contact between either male connector member  94  or female connector member  98  and the spinous processes. 
       FIG. 10  is a perspective view of another embodiment of a female connector member  120  in accordance with the present invention. Female connector member  120  is formed similarly to female connector member  14  or connector  98 . Connector member  120  includes a distal end  122  defining a rod securing portion  124 , a proximal end  126 , and a shaft  132  therebetween. Proximal end  126  carries a body  128  with an aperture  130  therethrough. Body  128  includes a lower surface  134  having a number of radial splines or alternating ridges  136  and grooves  137  positioned circumferentially about aperture  130 . Ridges  136  and grooves  137  are provided to facilitate securing or locking female connector member  120  in a desired orientation. 
     Shaft  132  is disposed between distal end  122  and proximal end  126 . In the illustrated embodiment, shaft  132  is provided as an arched shaft similar to shaft  100  on female connector member  98 . In other embodiments, shaft  132  can be provided as a straight shaft such as shaft  82  in  FIG. 1 . Furthermore, shaft  132  can be provided to have any desired cross-sectional configuration, including round, oval, rectangular, and the like. In still alternative embodiments, shaft  132  can be provided as a plate having a substantially uniform cross section, e.g., a rectangular cross section extending from proximal end  126  to distal end  122 . 
       FIG. 11  is an exploded view of an alternative embodiment of an interconnecting assembly  140  for use in the present invention. Interconnecting assembly  140  includes eyebolt  142 , a washer body  144 , and a fastener  146 . 
     Eyebolt  142  includes a lower body  148  having an aperture  150  extending therethrough. A threaded stud  152  extends upwardly from body  148  substantially orthogonal to the central axis  154  of aperture  150 . 
     Washer body  144  includes an upper surface  158 , a lower surface  166 , and an opening  159  therethrough sized to receive a portion of lower body  148 . Upper surface  158  includes a plurality of ridges or radial splines  160  and grooves  161  positioned circumferentially around an opening  159 . In a preferred embodiment, splines  162  are sized and spaced from each other to matingly engage with ridges  136  on female connector member  120  in  FIG. 10 . Lower surface  166  is positioned opposite upper surface  158 . In a preferred embodiment, lower surface  166  is provided to bear against a shaft of a male connector member (not shown). In a preferred embodiment, lower surface  166  includes a recess  168 , more preferably a pair of recesses diametrically opposed about opening  159 . When secured with fastener  146 , recess(es)  168  bear(s) against and contacts a shaft of an inserted male connector member and inhibits rotation of the male connector member about stud  152  relative to the included female connector member. 
       FIG. 12  is a perspective view of a connector assembly  174  having splined locking surfaces in accordance with the present invention. Connector assembly  174  includes a male connector member  176 , a female connector member  178 , and interconnecting element  180 . Male connector member  176  can be provided substantially as has been described for member  94 . Female connector member  178  can be provided substantially as has been described for member  140 . Similarly, interconnecting element  180  can be provided substantially as has been described for element  120 . It can be observed in the illustrated embodiment that female connector member  178  is rotatable about an axis  181  defined by fastener  182  to any desired orientation relative to male connector member  176 . When the surgeon has positioned either connecting member  178  or  176  in a desired orientation, the surgeon can then tighten fastener  182  to interdigitating splines  184  and  186  to securely lock the two members in the desired orientation. 
       FIG. 13  is an exploded view of another embodiment of a connector assembly in accordance with the present invention. Connector assembly  194  includes a male connector member  196 . Male connector member  196  can be provided substantially as has been described for male connector member  12 . In alternative embodiments, member  196  can be provided with an arched shaft as described for connector  94 . As noted before, the shaft can be provided with a variety of cross-section profiles. Connector assembly  194  also includes an interconnection element  200 . Interconnection element  200  is provided as an eyebolt  202  with an aperture  204  formed therein and a stud  206  extending substantially orthogonal to the central axis  205  of aperture  204 . Eyebolt  202  can be provided substantially as described for eyebolt  44 . 
     Assembly  194  also includes a washer or an insert  210  to be slideably received on stud  206 . In the illustrated embodiment, insert  210  is configured as a substantial cylindrical washer having a partial spherical cross section. Insert  210  also includes an internal bore  212  dimensioned and configured to be received over stud  206  and, optionally, an upper portion of eyebolt  202 . 
     Referring additionally to  FIGS. 14 ,  14   a , and  14   b , insert  210  is illustrated for use in assembly  194 .  FIG. 14  is a side elevation view.  FIG. 14   a  is a cross-section view taken along section line  14 - 14 , and  FIG. 14   b  illustrates the lower surface  230  of insert  210 . It can be observed that lower surface  230  includes recesses  232  and  234 . Recesses  232  and  234  are provided to bear against and contact a portion of shaft  198  of male connector member  196 . In addition or in the alternative, insert  210  includes a slit  236  formed in its side wall  238 . Slit  236  allows insert  210  to vary in dimension, if necessary, to receive stud  206  within bore  212 . Additionally, slit  236  can allow insert  210  to deform and frictionally engage one or more of stud  206 , female connector member  216 , and male connector member  196  to eyebolt  202 . Insert  210  can be formed of a biocompatible material including surgical steel, stainless steel, titanium, a ceramic, a composite, a deformable, and/or a flexible material such as a polymeric material—preferably an elastic polymeric material. 
     Referring specifically to  FIG. 13 , female connector member  216  includes a proximal end  218  having an bore or aperture  220  formed therein, a distal end  222  defining a rod securing portion  225 , and a shaft therebetween. Aperture  220  adjacent proximal end  218  is configured to receive insert  210 . In one form, aperture  220  is sized and configured as a socket with the insert designed as the “ball” of a ball and socket joint. In another form, aperture  220  has a smooth cylindrical bore having a substantially uniform internal diameter throughout. In yet other forms, aperture  220  has a bore with an internal diameter that is greater than the diameter of one or more of the openings  221  or  223  leading into the interior portion of aperture  220 . The larger internal diameter is sized to matingly engage or receive insert  210  therein. In this form, female connecting member  216  can pivot about insert  210 , which is disposed within the internal bore of aperture  220 . 
     The distal end of female connector member  216  defines a rod securing portion. Additionally, distal end  222  includes a threaded aperture  226 . In a preferred embodiment, the rod securing portion includes a hook and the threaded aperture  226  extends from an upper surface on female connector member  216  into the crook portion of hook  224 . 
     Fastener  228  is provided to threadedly engage with stud  206 . In a preferred embodiment, stud  206  includes external threads  227 , and fastener  228  contains internal threads  229  configured to matingly engage with the external threads  227  of stud  206 . Additionally, fastener  228  has an external dimension or diameter selected to be at least partially received within aperture  220  and, optionally, within a portion of the internal recess  211  of insert  210 . 
     In use, shaft  198  of male connector member  196  is received within aperture  204  of the eyebolt  202 . Thereafter, insert  210  is positioned over stud  206  in contact with a portion of shaft  198 . Female connector member  216  is then engaged to or forced over insert  210 . In this fashion, insert  210  is received within the aperture  220  of female connector member  216 . Fastener  228  then engages with stud  206  to initially assemble the connector assembly—albeit while allowing the male and female connector members  196  and  216  restricted movement, both to extend the length of the resulting assembly and the relative orientation of the male and female connector members  196  and  216  to each other. It will be observed from the illustration in  FIG. 12  that female connector member  216  can move or rotate about an axis defined by stud  206  and pivot along or in line with that same axis. Additionally, it can be observed that when insert  210  is provided with a hemispherical cross section, female connector member  216  can pivot about multiple axes. Consequently, a surgeon can position the male and female connector members  196  and  216  to circumvent contacting the neural structures or processes along the spinal column. 
     Securing fastener  228  tightly onto stud  206  forces the insert  210  to expand and frictionally engage the internal portion of aperture  220  and optionally stud  206 . This in turn locks the male connector member  196  within aperture  204  and prevents female connector member  216  from movement relative to male connector member  196  and/or interconnection element  200 . 
       FIG. 15  is a perspective view of another embodiment of a connector assembly  246  in accordance with the present invention. Connector assembly  246  is provided substantially as has been described for connector assembly  194  in  FIG. 13 . However, as can be seen from the illustration, female connector member  248  and male connector member  250  include a plate  252  and  254 , respectively, in lieu of cylindrical shafts extending to the proximal end to the distal end of the respective members. Furthermore, it can be seen from the illustration that female connector member  248  is provided at an angle and is non-planar with male connector member  250 . In this configuration, connector assembly  246  can secure two elongate members. The two secured elongate members need not be positioned parallel nor lie in the same plane with each other. When viewed along a longitudinal axis defined by the elongate female connector member  248 , the connector assembly appears to twist from a first end  255  to a second end  256 . This can allow a surgeon to exert the desired force and direction on a particular vertebra to correct various spinal deformities. 
       FIG. 16  is a cross-sectional view of yet another embodiment of a female connector member  280  for use in the present invention. Member  280  includes a shaft  281  disposed between distal end  282  and proximal end  286 . Distal end  282  defines a spinal rod connecting portion  284 . Rod connecting portion  284  can be configured substantially as described for portion  32  in  FIG. 1 . Proximal end  286  carries an interconnector body  288 . Interconnecting body  288  includes an aperture  290  extending therethrough and defining a central axis  294 . Axis  294  is positioned to lie substantially in the same plane as shaft  281 . Aperture  290  is provided to receive an insert such as an insert described above; for example, insert  210 . In this embodiment, female connector member  280  is provided as a one-piece unit including the interconnecting body. 
     Aperture  290  is provided as a cylindrical or oval bore. In selected embodiments, aperture  290  need not have a constant or uniform diameter throughout. Preferably, aperture  290  is provided with enlarged openings  296  and  298 . Further, central portion  297  of aperture  290  is sized and configured to receive an insert, such as inset  210  of  FIG. 14 . 
     Additionally, body  288  includes a threaded opening  292  disposed to lie about an axis positioned substantially orthogonal to the axis  294  of aperture  290 . Opening  292  is provided with a threaded interior surface to threadedly receive a fastener such as fastener  36  in  FIG. 1 . 
       FIG. 17  is a cross-sectional view of a connector assembly  300 . Connector assembly  300  includes female connector member  280  and male connector member  302 . Male connector member  302  includes a proximal end  303  and shaft  304  that are sized and configured to be received within aperture  290  of interconnecting body  288 . Additionally, an insert such as an insert that has been described in  FIGS. 13 ,  14 ,  14   a , and  14   b  can be included in the aperture of the interconnecting body. In a preferred embodiment, proximal end  303  is slideably received within the internal bore  212  of insert  210  and through aperture  290  of interconnecting body  288 . In this embodiment, shaft  304  and shaft  281  nest together. Preferably each of shaft  304  and  281  has approximately the same curvature and cross-sectional dimensions. Since aperture  290  is provided with enlarged openings  296  and  298 , as discussed above, male connector  302  can pivot about the central portion  297  of aperture  290 . Consequently, female connector  280  and male connector  302  can be adjusted to be aligned with each other or at an angle oblique (either laterally and/or vertically) to each other as desired. In use, the surgeon can adjust female connector  280  and male connector  302  to engage in spinal rods (not shown) that are parallel or non parallel with each other. Thereafter, a fastener  307  having external threads can be threadedly engaged within opening  292 , locking the two components, i.e., the male connector  302  and female connector  280 , in the desired orientation. 
     In a preferred embodiment, the individual components of connector assembly  300  can be assembled prior to surgery. The resulting assembly can be maintained as a single, adjustable unit allowing restricted movement of female connector member  280  relative to male connector member  302 . This can greatly increase ease of use and facilitate implantation of the device. 
       FIG. 18  illustrates connector assembly  300  in a fully extended and/or arched (bent) configuration. Male connector member  302  has been positioned inside aperture  290  such that proximal end  303  is adjacent interconnection body  288 . Consequently, connector assembly  300  can be adjusted to define an angle  308  (considering the relative orientation of shafts  281  and  304 ) of between about 100° and about 80°. After the surgeon has positioned the male connector and female connector as desired, fastener  307  can be tightened to lock the interconnection assembly to the desired orientation. It should be understood that interconnection assembly  300  can be secured to elongate members either before or after tightening fastener  307 . 
     Referring additionally to  FIG. 19 , there is shown another embodiment of an interconnector assembly  310 . As has been described above, connector assembly  310  includes two connecting members, female connector member  312  and male connector member  314 . Assembly  310  includes a ball and socket interconnection element  320 . Interconnector element  320  can be provided as a substantially rectangular cross section with a fastener  322  seated within the internal portion of the element. This can provide a low-profile crosslinking element that does not extend posteriorly from the structures of the spinal column and associated processes. 
     A pair of elongate members  316  and  318  are illustrated secured to the interconnector assembly  310 . One elongate member is secured to the distal ends of the connector members  312  and  314 , respectively. It can be observed that elongate member  318  is not positioned to lie parallel to or in the same plane as elongate member  316 . 
       FIG. 20  is a perspective view of another embodiment of an insert  260  for use in the present invention. Insert  260  includes a substantially cylindrical body  261  having an upper surface  262  with a concave recess  264  formed therein. Insert  260  can be used in lieu of or in addition to insert  210 . In a preferred embodiment, insert  260  is disposed in the aperture of the interconnection body or eyebolt such as those illustrated in  FIGS. 1 ,  8 ,  10 , and  12 . 
       FIG. 21  is a perspective view of yet another embodiment of an insert  268  in accordance with the present invention. Insert  268  includes an upper surface  272  and a recess  274  formed therein. Recess  274  includes upwardly extending side walls and a bottom or trough  263  therebetween. Recess  274  is provided to exhibit a substantially rectangular or square cross-sectional area and is sized to receive a shaft having a rectangular cross-sectional profile. Insert  268  can be disposed in an eyebolt similar to insert  260  illustrated in  FIG. 20  to receive and bear against a substantially square or rectangular shaft of a male connector member which has been inserted therein. The shaft of the connector member can rest against the bottom  263  of the recess  274 . In one embodiment, the bottom  263  can be frictionally engaged with the shaft and thus secure the shaft within the interconnection body shaft. 
     In yet other embodiments, the present invention can include an insert formed as a circular O-ring provided to frictionally engage either a shaft of a connecting member and/or the stud of the interconnecting element. 
     Inserts  260  and  268  can be formed of a biocompatible material. Preferably inserts  260  and  268  are formed of a material that will induce restricted movement of the male shaft within the aperture. Examples of these materials include metallic materials, ceramics, composites, and preferably elastomeric materials. 
     Referring now to  FIG. 22 , a female interconnector member  275  is illustrated specifically for use with a frictional insert such as inserts  260  and  274 . Interconnector member  275  includes an interconnecting body  276  carried on proximal end  277 . An aperture  279  extends through interconnecting body  276 . Aperture  279  is sized to receive a male connector member such as male member  12 ,  94 ,  176 ,  196 , or  302 . Additionally, interconnecting body  276  includes a well  278  within aperture  279 . Insert  260  is disposed within well  278  with the concave recess  264  aligned an aperture  279 . Insert  260  can receive or partly encircle the shaft of the male connector member received therein. Consequently, movement of the shaft within aperture  279  (and the concave recess  264 ) is restricted depending upon the amount force induced by tightening fastener  307 . The components, i.e., the male and female connectors, insert, and fasteners, can be provided pre-assembled by the manufacturer to the surgeon. The pre-assembled components allow limited movement of the connectors and, consequently, facilitate the implantation of the interconnection assembly during surgery. 
       FIG. 23  is an exploded partial view of yet another embodiment of an interconnecting assembly  330  in accordance with the present invention. Interconnecting assembly  330  includes an interconnecting element  332 , a male connector member  334 , a female connector member  336  (shown in cross-sectional view through body  346 ), and a fastener  338 . Interconnecting element  332  is provided as a substantially cylindrical body having an aperture  340  extending therethrough. In a preferred embodiment, aperture  340  is provided as non-round, more preferably having an oval cross section. Aperture  340  is provided to slideably receive a portion of male connector member  334 . Interconnecting element  332  includes a first end  342  and an opposite second end  341 . First end  342  includes a rim or ridge portion  344  adapted to engage within the interior of a portion of female connector member  336 . The combination of ridge portion  344  and female connector member  336  provides a click-lock engagement to initially secure the female connector member  336  to the interconnecting element  332  while still allowing relative movement of each component. 
     Referring additionally to  FIG. 24 , which illustrates a cross-sectional view of female connector member  336 , it can be observed that the interior of the body  346  includes a groove  348  to engage and contact the ridge portion  344 . When body  346  is initially inserted onto the top of interconnecting element  332 , ridge portion  344  engages into groove  348 . In preferred embodiments, ridge portion  344  is provided with a sloped or inclined surface extending from first end  343  to second end  345  to facilitate insertion into body  346 . Additionally, ridge portion  344  includes a locking portion or step  350  that can bear against and contact the internal portion of groove  348  to prevent the female connector member  336  from backing out of the interconnecting element  332 . This provides an initial locking connection between the two components. However, while thus engaged, each of male connector member  334 , female connector member  336 , and interconnecting element  332  are freely adjustable without requiring disengagement of any of these components. 
     Referring additionally to  FIG. 24 , a cross-sectional view of the interconnecting element  332  is illustrated. In preferred embodiments, the male connector member  334  and female connector member  336  can be locked in a desired orientation (relative to each other) by torqing down fastener  338  into the threaded interior of body  346 . Tightening down fastener  338  serves to secure the female portion  336  to body  346 . Additionally, the lower surface  352  of body  346  engages with a portion of shaft  354  as illustrated in  FIG. 23 . 
       FIGS. 25 through 29  illustrate another embodiment of an interconnecting assembly  360  in accordance with the present invention. Connecting assembly  360  can be provided as a dual connector. In preferred embodiments, the dual connector is provided as one-piece unit that includes two or more spinal rod connecting portions  364 ,  366  depending from a common rod or bar  361 . In the illustrated embodiment, connecting portions  364  and  366  are aligned—substantially parallel with each other. 
     It can be observed that spinal rod connecting portion  366  is provided to include a saddle or ridge  368  extending along the circumferential interior of the hook portion  370 . The interior surface  362  curves both vertically from bar  361  to tip  363  and laterally from a first side  365   a  to a second, opposite side  365   b . In other embodiments interior surface  362  curves in a first direction and also curves in a second direction that is oblique to the first direction. In alternative embodiments, interior surface  362  curves in a second direction that is orthogonal to the first direction or at an angle that is either acute or obtuse to the first direction. Further, the amount of curvature or degree can vary as desired. 
     The saddle ridge  368  is provided to allow an included spinal rod to rest within the hook portion  370  at a variable angle with respect to a spinal rod that has been contained within portion  364 . In alternative embodiments, both spinal rod securing portions  364  and  366  can include a ridge or saddle similar to  368  and surface  362 . In this embodiment, the angles between the two included spinal rods  367  and  369  (illustrated in  FIGS. 28 and 29 ) can vary widely. Furthermore, the two included spinal rods can be secured together while they lie in different planes, i.e., when the two rods do not lie in the same plane. 
       FIG. 30  illustrates yet another embodiment of a male connector member  371 . It can be observed that male connector member  371  includes a shaft  372  having a projection  374  for engaging with an interconnecting body similar to that shaft  26  and projection  28  of male connector member  12  in  FIG. 1 . Male connector member  371  includes a spinal rod securing portion  376  having a saddle or ridge  378  extended about the internal circumference of hook portion  380 . Ridge  378  (similar to ridge  368 ) allows an included spinal rod to be secured in a variety of orientations. Additionally, as has been described with other male connector members in the present application, a threaded aperture  387  can be used in combination with a threaded fastener (see  FIGS. 1 ,  6   a  and  6   b ) to bear against and secure an elongate member. 
       FIG. 31  is a diagrammatic illustration of a spinal column  386  including a pair of elongate members  388  and  390 . Elongate members  388  and  390  can be spinal rods. Further, it will be understood that the elongate members can be either shorter or longer than illustrated. Additionally, the elongate members can be positioned to various locations on the spinal column and attached to different anatomical structures of the vertebrae. Elongate members  388  and  390  are interconnected with a plurality of interconnector assemblies  392 ,  394 , and  396  provided as described herein. The interconnecting assemblies  392 ,  394 , and  396  can be selected among any of those described in the present application including  10 ,  110 ,  174 ,  194 ,  246 ,  300 ,  310 ,  360 , and  371 . In some embodiments, the connector assemblies need not be the same connector assemblies; that is, connector assembly  392  need not be the same as  394 , which need not be the same as  396 . The various components of the spinal fixation systems described herein are preferably formed of a biocompatible material including stainless steel, titanium, and other suitable metals and/or metal alloys according to known methods. 
     Further, while various embodiments of a system for spinal fixation having specific components and structures are described and illustrated herein, it is to be understood that any selected embodiment can include one or more of the specific components and/or structures described for another embodiment where possible and as such are intended to be within the scope of the present invention. 
     Any reference to a specific directions, for example, references to up, upper, down, lower, vertical and horizontal and the like, is to be understood for illustrative purposes only or to better identify or distinguish various components from one another. These references are not to be construed as limiting in any manner to the system for spinal fixation and/or methods as described herein. 
     The present invention contemplates modifications as would occur to those skilled in the art. It is also contemplated that components and systems embodied in the present invention can be altered, rearranged, substituted, deleted, duplicated, combined, or added to other processes as would occur to those skilled in the art without departing from the spirit of the present invention. In addition, the various stages, steps, procedures, techniques, phases, and operations within these processes may be altered, rearranged, substituted, deleted, duplicated, or combined as would occur to those skilled in the art. All publications, patents, and patent applications cited in this specification are herein incorporated by reference as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference and set forth in its entirety herein. 
     Further, any theory of operation, proof, or finding stated herein is meant to further enhance understanding of the present invention and is not intended to make the scope of the present invention dependent upon such theory, proof, or finding. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is considered to be illustrative and not restrictive in character, it is understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.