Patent Publication Number: US-2012029571-A1

Title: Adjustable Connector for Interconnecting Elongate Rod Members at Variable Angular Orientations

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to treatment of the spinal column, and more particularly relates to an adjustable connector for interconnecting elongate rod members at variable angular orientations relative to one another. 
     BACKGROUND 
     Spinal fixation systems are used to adjust, align, stabilize and/or support various portions of the spinal column or other bony structures such as the pelvis, the skull and/or the occiput. One or more elongate spinal rods may be positioned and anchored along the spinal column to provide support and/or to properly position spinal components relative to one another for treatment purposes. Various types of anchors, including bolts, screws and hooks, are commonly used to anchor the elongate spinal rods to the vertebrae. 
     In some instances, it may be desirable to interconnect two elongate spinal rods together in a side-by-side arrangement at a particular angular orientation such as, for example, when attaching a spinal rod to an existing spinal construct that is already anchored to the spinal column. Various types of connectors have been used to interconnect elongate members to one another. However, prior connector designs have typically been provided with a static configuration wherein the relative angular orientation between the elongate spinal rods is fixed and non-variable. In some instances, it may be desirable to variably position the elongate spinal rods at a select angular orientation, either prior to or during a surgical procedure, due to anatomical features of the patient, the particular physiological problem being treated, and/or the preference of the physician. Although the relative angular orientation between elongate spinal rods may be adjusted via bending or contouring, such techniques are imprecise, rely on the application of significant bending forces, and tend to weaken or degrade the rods. 
     Thus, there remains a need for an improved connector for interconnecting elongate rod members at variable angular orientations relative to one another. The present invention satisfies this need and provides other benefits and advantages in a novel and unobvious manner. 
     SUMMARY 
     The present invention relates generally to treatment of the spinal column, and more particularly relates to an adjustable connector for interconnecting elongate rod members at variable angular orientations relative to one another. While the actual nature of the invention covered herein can only be determined with reference to the claims appended hereto, certain forms of the invention that are characteristic of the preferred embodiments disclosed herein are described below. 
     It is one object of the present invention to provide an adjustable connector for interconnecting elongate rod members at variable angular orientations relative to one another. Further objects, features, advantages, benefits, and aspects of the present invention will become apparent from the drawings and description contained herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side perspective view of an adjustable connector according to one form of the present invention. 
         FIG. 2  is an exploded side perspective view of the adjustable connector shown in 
         FIG. 1 . 
         FIG. 3  is a side view of the adjustable connector shown in  FIG. 1 . 
         FIG. 4  is a top view of the adjustable connector shown in  FIG. 1 . 
         FIG. 5  is a cross sectional view of the adjustable connector, as taken along line  5 - 5  of  FIG. 4 . 
         FIG. 6  is a side perspective view of a first connector block associated with the adjustable connector shown in  FIG. 1 . 
         FIG. 7  is a side view of the first connector block shown in  FIG. 6 . 
         FIG. 8  is an end view of the first connector block shown in  FIG. 6 . 
         FIG. 9  is a cross sectional view of the first connector block shown in  FIG. 6 , as taken along line  9 - 9  of  FIG. 8 . 
         FIG. 10  is a side view of a second connector block associated with the adjustable connector shown in  FIG. 1 . 
         FIG. 11  is an end view of the second connector block shown in  FIG. 10 . 
         FIG. 12  is a cross sectional view of the second connector block, as taken along line  12 - 12  of  FIG. 11 . 
         FIG. 13  is a side perspective view of a first side of a splined washer associated with the adjustable connector shown in  FIG. 1 . 
         FIG. 14  is a side perspective view of an opposite second side of the splined washer shown in  FIG. 13 . 
         FIG. 15  is a side view of the splined washer shown in  FIG. 14 . 
         FIG. 16  is a side view of a retaining clip associated with the adjustable connector shown in  FIG. 1 . 
         FIG. 17  is an end view of the retaining clip shown in  FIG. 16 . 
         FIG. 18  is a perspective view of the adjustable connector shown in  FIG. 1 , as engaged with a pair of spinal rods. 
         FIG. 19  is a perspective view of an adjustable connector according to another form of the present invention, as engaged with a pair of spinal rods. 
         FIG. 20  is a side view of an adjustable connector according to another form of the present invention. 
         FIG. 21  is a side perspective view of an adjustable connector according to another form of the present invention. 
         FIG. 22  is an exploded side perspective view of the adjustable connector shown in  FIG. 21 . 
         FIG. 23  is a cross sectional view of the adjustable connector shown in  FIG. 21 . 
     
    
    
     DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is hereby intended, and that alterations and further modifications to the illustrated devices and/or further applications of the principles of the invention as illustrated herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     In general, the present invention relates to an adjustable connector for interconnecting elongate members at variable angular orientations relative to one another. In a specific embodiment, the present invention is configured to rotatably couple a pair of elongate spinal rods together in a side-by-side manner at variable angular orientations. The adjustable connector includes a first connector member defining a first passage for receiving a first elongate rod, and a second connector member defining a second passage for receiving a second elongate rod, with the first and second connector members interconnected via a swivel or rotor mechanism to permit the connector members and the elongate rods to be rotatably positioned at various angular orientations relative to one another. The adjustable connector further includes a locking mechanism configured to lock the connector members (and in turn the elongate rods) at a select angular orientation relative to one another. In one embodiment, each of the connector members includes a threaded transverse bore that intersects the rod-receiving passage, and a set screw threaded into the transverse bore and into engagement with the elongate rod to securely capture the elongate rod within the rod-receiving passage. In another embodiment, each of the connector members may be provided with a pair of threaded transverse bores that intersect the rod-receiving passage, with a pair of set screws threaded into the transverse bores and into engagement with the elongate rod to securely capture the elongate rod within the rod-receiving passage. 
     Referring to  FIGS. 1-5 , shown therein is an adjustable connector  20  according to one form of the present invention for interconnecting elongate rod members R 1 , R 2  (shown in phantom in  FIGS. 3 and 4 ) at variable angular orientations relative to one another. In the illustrated forms of the present invention, the adjustable connector embodiments are illustrated and described as interconnecting elongate spinal rods. However, it should be understood that in other forms of the present invention, one or more of the adjustable connector embodiments may interconnect other types and configurations of spinal implants, including bolts, screws and other components used in association with spinal constructs. It should also be understood that the embodiments of the adjustable connector may be used in fields outside of the spinal field including, for example, in fixation or stabilization systems that are attached to other bony structures such as the pelvis, the skull and/or the occiput. 
     The illustrated embodiment of the adjustable connector  20  generally includes a first connector member or block  22  configured for coupling with a first spinal rod R 1  extending generally along a first longitudinal axis L 1 , and a second connector member or block  24  configured for coupling with a second spinal rod R 2  extending generally along a second longitudinal axis L 2 . The illustrated embodiment of the adjustable connector  20  also includes a lock member  26  at least partially positioned between the first and second connector members  22 ,  24  and configured to aid in selectively preventing relative rotational movement between the first and second connector members  22 ,  24  about a rotational axis R, and a retainer member  28  configured to maintain rotational engagement between the first and second connector members  22 ,  24 . The illustrated embodiment of the adjustable connector  20  further includes a first compression member  32  extending generally along a transverse axis T 1  and configured to engage the first spinal rod R 1  with the first connector member  22 , and a second compression member  34  extending generally along a transverse axis T 2  and configured to engage the second spinal rod R 2  with the second connector member  24 . 
     As will be discussed in greater detail below, the adjustable connector  20  is configured to permit relative rotational movement between the first and second connector members  22 ,  24  about the rotational axis R to allow variation in the angular orientation of the first spinal rod R 1  relative to the second spinal rod R 2 , and more specifically between the longitudinal axes L 1 , L 2  of the spinal rods. The adjustable connector  20  is also configured to selectively prevent relative rotational movement between the first and second connector members  22 ,  24  about the rotational axis R to secure the first and second spinal rods R 1 , R 2  at a select angular orientation relative to one another, the details of which will be discussed below. 
     The first connector member  22  includes a first passage  40  sized and configured to receive the first spinal rod R 1  therein, and the second connector member  24  includes a second passage  60  sized and configured to receive a portion of the second spinal rod R 2  therein. In the illustrated embodiment of the adjustable connector  20 , the rod-receiving passage  40  has an open configuration defining a lateral opening  41  sized to laterally receive the spinal rod R 1  therethrough such that the spinal rod R 1  may be laterally or transversely inserted into the passage  40 . Specifically, the rod-receiving passage  40  has a U-shaped or C-shaped configuration to allow the spinal rod R 1  to be laterally inserted through the lateral opening  41  and into the rod-receiving passage  40  in a direction transverse or normal to the longitudinal axis L 1  of the spinal rod R 1 . In the illustrated embodiment of the connector member  22 , the lateral opening  41  opens onto a side portion of the first connector member  22  and is arranged generally along the rotational axis R to permit side loading of the spinal rod R 1  into the rod-receiving passage  40 . However, it should be understood that the opening  41  may open in other directions to allow top loading, bottom loading, or angled transverse loading of the spinal rod R 1  into the rod-receiving passage  40 . Additionally, in the illustrated embodiment of the adjustable connector  20 , the second rod-receiving passage  60  has a closed configuration such that the spinal rod R 2  is axially inserted into the passage  60  in a direction extending generally along the longitudinal axis L 2  of the spinal rod R 2 . However, it should be understood that the first rod-receiving passage  40  may alternatively have a closed configuration such that the spinal rod R 1  may be axially inserted into the passage  40  and/or the second rod-receiving passage  60  may alternatively have an open configuration such that the spinal rod R 2  may be laterally or transversely inserted into the passage  60 . 
     Additionally, the first connector member  22  includes an aperture  42  communicating with the rod-receiving passage  40  and extending generally along a transverse axis T 1  for receiving the first compression member  32  therethrough. The aperture  42  is positioned and oriented such that displacement of the compression member  32  through the aperture  42  closes off at least a portion of the lateral opening  41  to capture the spinal rod R 1  within the rod-receiving passage  40 . In a specific embodiment, the transverse axis T 1  of the aperture  42  is laterally offset from the longitudinal axis L 1  of the spinal rod R 1  and is oriented substantially perpendicular or normal to the rotational axis R and the longitudinal axis L 1 . However, it should be understood that other positions and orientations of the transverse axis T 1  of the aperture  42  are also contemplated, including positions where the transverse axis T 1  intersects the longitudinal axis L 1  and/or where the transverse axis T 1  is oriented at an oblique angle relative to the rotational axis R and/or the longitudinal axis L 1 . The second connector member  24  includes an aperture  62  communicating with the rod-receiving passage  60  and extending generally along a transverse axis T 2  for receiving the second compression member  34  therethrough. In the illustrated embodiment, the aperture  62  and the transverse axis T 2  are oriented at an angle α relative to the rotational axis R. In a specific embodiment, the angle α is approximately 75 degrees. However, other angles α are also contemplated as falling within the scope of the present invention. Additionally, in the illustrated embodiment, the transverse axis T 2  of the aperture  62  may be positioned to intersect the longitudinal axis L 2  of the spinal rod R 2 . However, it should be understood that other positions and orientations of the aperture  62  and the transverse axis T 2  are also contemplated, including positions and orientations wherein the transverse axis T 2  is offset from the longitudinal axis L 2  of the spinal rod R 2 . 
     In the illustrated embodiment, the compression members  32 ,  34  are each configured as a set screw, and the apertures  42 ,  62  in the first and second connector members  22 ,  24  are internally threaded so as to threadingly receive the set screws  32 ,  34  therethrough. In the illustrated embodiment, the set screws  32 ,  34  each have a break-off configuration, including a threaded body portion  36  and a break-off head portion  38 . However, it should be understood that other types and configurations of the compression members or set screws  32 ,  34  are also contemplated as falling within the scope of the present invention, including non-threaded compression members and set screws that do not include a break-off head portion. Furthermore, although the illustrated embodiment of the adjustable connector  20  utilizes a single set screw for use in association with each of the connector members  22 ,  24  to secure the spinal rods R 1 , R 2  within the rod-receiving passages  40 ,  60 , in other embodiments, two or more set screws may be used in association with each of the connector members  22 ,  24  to secure the spinal rods R 1 , R 2  within the rod-receiving passages  40 ,  60 . 
     In one embodiment, the threaded body portion  36  of the set screws  32 ,  34  includes a rod-engaging surface  37  ( FIG. 3 ) configured for engagement with an exterior surface of the spinal rods. Additionally, the break-off head portion  38  of the set screws  32 ,  34  includes a tool receiving recess  39  ( FIG. 4 ) configured to receive a distal end portion of a driver instrument (not shown). In one embodiment, the tool receiving recess  39  has a Torx-shaped configuration. However, other shapes configurations are also contemplated. In a further embodiment, when the set screws  32 ,  34  are fully engaged with the spinal rods and the head portion  38  is broken away from the threaded body portion  36 , the end of the threaded body portion  36  is preferably positioned substantially flush with an outer surface of the connector member  22 ,  24  to provide the connector with a lower overall profile. 
     As should be appreciated, since the set screw  32  and the aperture  42  extend along a transverse axis T 1  that is outwardly offset relative to the longitudinal axis L 1  of the spinal rod R 1 , displacement of the set screw  32  through the aperture  42  and into engagement with the spinal rod R 1  will urge the spinal rod R 1  in a lateral direction relative to the transverse axis T 1  to compress the spinal rod R 1  against a rod-engaging surface  43  that partially surrounds the rod-receiving passage  40 . Compression of the spinal rod R 1  against the rod-engaging surface  43  secures the spinal rod R 1  within the passage  40  to substantially prevent further axial or rotational movement of the spinal rod R 1  relative to the first connector member  22 . In the illustrated embodiment, the rod-engaging surface  43  has a circular configuration defining an inner radius that is substantially equal to the outer radius of the spinal rod R 1 . However, other shapes and configurations of the rod-engaging surface  43  are also contemplated, including non-arcuate configurations and configurations wherein the inner radius of at least a portion of the rod-engaging surface  43  is reduced relative to the outer radius of the spinal rod R 1  so as to provide two lines of contact between the rod-engaging surface  43  and the spinal rod R 1 . 
     As should also be appreciated, since the set screw  34  and the aperture  62  extend along a transverse axis T 2  that is generally aligned with the longitudinal axis L 2  of the spinal rod R 2 , displacement of the set screw  34  through the aperture  62  and into engagement with the spinal rod R 2  will urge the spinal rod R 2  in a direction generally along the transverse axis T 2  to compress the spinal rod R 2  against an engagement surface defined by the lock member  26 , the details of which will be set forth below. Compression of the spinal rod R 2  against the lock member  26  secures the spinal rod R 2  within the rod-receiving passage  60  to substantially prevent further axial or rotational movement of the spinal rod R 2  relative to the second connector member  24 . Additionally, as will also be discussed below, compression of the spinal rod R 2  against the lock member  26  also serves to lock the connector members  22 ,  24  and the spinal rods R 1 , R 2  at a select angular orientation relative to one another. 
     Referring now to  FIGS. 6-9 , shown therein are additional details regarding the first connector member  22 . As indicated above, the first connector member  22  includes a rod-receiving passage  40  defining a lateral opening  41 , a threaded aperture  42  in communication with the rod-receiving passage  40  and extending generally along a transverse axis T 1 , and a rod-engaging surface  43  at least partially surrounding the passage  40 . Additionally, the first connector member  22  includes an opening or recess  44  extending from an outer interface surface  46  and arranged generally along the rotational axis R. As will be discussed in greater detail below, the axial opening  44  is sized and configured to receive a shaft or stem portion  64  extending from the second connector member  24  ( FIGS. 10-12 ) and arranged generally along the rotational axis R. The axial opening  44  and the axially-extending shaft  64  cooperate with one another to permit rotation of the first connector member  22  relative to the second connector member  24  about the rotational axis R. Although the illustrated embodiment of the adjustable connector  20  provides the first connector member  22  with the axial opening  44  and the second connector member  24  with the axial shaft  64 , it should be understood that in other embodiments, the first connector member  22  may be provided with the axial shaft  64  and the second connector member  24  may be provided with the axial opening  44 . As will be discussed in detail below, the adjustable connector  20  is configured such that the axial shaft  64  is provisionally and positively captured within the axial opening  44  to maintain engagement between the first and second connector members  22 ,  24  prior to positioning of the first and second spinal rods R 1 , R 2  within the first and second rod-receiving passages  40 ,  60 , while still allowing relative rotation between the connector members  22 ,  24  about the rotational axis R. 
     In one embodiment, the axial opening  44  in the first connector member  22  has a circular configuration and includes an outwardly tapering portion  48  opening onto the outer interface surface  46  of the first connector member  22  to facilitate insertion of the shaft portion  64  of the second connector member  24  into the axial opening  44 . The axial opening  44  further includes an enlarged cross sectional portion or undercut region  50  that may be provided in the form of an annular groove extending about the rotational axis R, the purpose of which will be discussed below. Additionally, the axially-facing interface surface  46  of the first connector member  22  includes interengagement structures  52 . In one embodiment, the interengagement structures  52  comprise a number of radially-extending splines and grooves positioned about the axial opening  44 . In the illustrated embodiment, the radially-extending splines and grooves  52  are positioned entirely about the axial opening  44 . However, it should be understood that the radially-extending splines and grooves  52  may instead be positioned about only a portion of the axial opening  44 . Additionally, although the illustrated embodiment of the invention depicts the interengagement structures  52  as radially-extending splines and grooves, it should be understood that other types and configurations of interengagement structures are also contemplated for use in association with the present invention. The first connector member  22  may also be provided with tool receiving grooves or recesses  54  defined along opposite sides of the connector member  22  sized and configured for receipt of end portions of an insertion tool or manipulation instrument (not shown). 
     Referring now to  FIGS. 10-12 , shown therein are additional details regarding the second connector member  24 . As indicated above, the second connector member  24  includes a closed rod-receiving passage  60  and a threaded aperture  62  in communication with the rod-receiving passage  60  and extending generally along the transverse axis T 2 . However, it should be understood that in other embodiments, the rod-receiving passage  60  may be open to allow for top loading, side loading or bottom loading of the rod into the passage. One such embodiment is illustrated in  FIG. 20  and described in detail below. 
     As illustrated in  FIGS. 10 and 12 , the rod-receiving passage  60  has a slot-like configuration that is elongated and has a length extending generally along the transverse axis T 2 . Additionally, the second connector member  24  includes a shaft or stem portion  64  extending generally along the rotational axis R and sized and configured for rotational engagement within the axial opening  44  in the first connector member  22  to permit rotation of the first connector member  22  relative to the second connector member  24  about the rotational axis R. The axial shaft  64  of the second connector member  24  includes a base portion  66  and an axially-extending stem portion  68  having an enlarged peripheral portion  70 . The enlarged peripheral portion  70  is sized and shaped for positioning within the undercut region  50  of the axial opening  44  in the first connector member  22  to provisionally and positively capture the axial shaft  64  within the axial opening  44  to maintain engagement between the first and second connector members  22 ,  24 . In the illustrated embodiment, the enlarged peripheral portion  70  of the axial shaft  64  comprises an annular flange located adjacent the distal end of the axial shaft  64  for positioning within the undercut region  50 . The enlarged annular flange  70  may define an angled distal end surface or chamfer  72  to facilitate insertion of the enlarged annular flange  70  into the axial opening  44 . In the illustrated embodiment, the base portion  66  of the axial shaft  64  has a generally rectangular configuration including flattened or truncated surfaces  67 , and the axial stem portion  68  has a generally circular outer cross section. However, it should be understood that other shapes and configurations of the base portion  66  and the axial stem portion  68  are also contemplated. 
     In one embodiment of the invention, the axial shaft  64  is transitionable from an initial configuration to a reduced transverse profile to allow axial passage of the enlarged annular flange  70  through the axial opening  44  to a position adjacent the undercut region  50  of the first connector member  22 . The shaft portion  64  is then expanded back toward the original configuration such that the enlarged annular flange  70  is outwardly expanded into the undercut region  50  of the axial opening  44  to provisionally and positively capture the axial shaft  64  within the axial opening  44 . In a specific embodiment, the axial shaft  64  has an elastically resilient configuration to allow the axial shaft  64  to be elastically and resiliently compressed to the reduced transverse profile to allow axial insertion into the axial opening  44 , and to then allow the enlarged annular flange  70  to be resiliently expanded into the undercut region  50 . 
     In a more specific embodiment, the axial shaft  64  includes an axial slot  74  extending from the distal end of the axial shaft  64  to the rod-receiving passage  60  to provide the shaft portion  64  with at least two elastically resilient leg portions  76   a ,  76   b  that are elastically compressed together to define the reduced transverse profile of the axial shaft  64  and which are resiliently expanded apart such that the enlarged flange  70  is positioned within the undercut region  50  of the axial opening  44 . In this manner, the axial shaft  64  is provisionally and positively captured within the axial opening  44  to maintain engagement between the first and second connector members  22 ,  24  prior to positioning of the first and second spinal rods rod R 1 , R 2  within the first and second rod-receiving passages  40 ,  60 . The second connector member  24  may also be provided with grooves or recesses  78  ( FIG. 12 ) defined along opposite sides of the base portion  66  of the axial shaft  64  for receipt of a material or substance such as, for example, a silicone adhesive material (not shown) and/or for receipt of end portions of an insertion tool or manipulation instrument (not shown). 
     Referring now to  FIGS. 13-15 , shown therein are additional details regarding the lock member  26 . As indicated above, the lock member  26  is configured to aid in selectively preventing relative rotational movement therebetween about the rotational axis R. In one embodiment of the invention, the lock member  26  has disc or washer-like configuration and is at least partially positioned between the first and second connector members  22 ,  24 . Additionally, the lock member  26  defines an opening  80  extending generally along the rotational axis R and sized and shaped to receive the base portion  66  of the axial shaft  64  of the second connector member  24  therethrough. In the illustrated embodiment, the opening  80  has a shape that corresponds to that of the base portion  66  of the axial shaft  64 . In one embodiment, the opening  80  has a generally rectangular configuration including flattened or planar surfaces  81 . However, it should be understood that other shapes and configurations of the opening  80  are also contemplated. Additionally, it should be appreciated that positioning of the rectangular-shaped base portion  66  of the axial shaft  64  within the rectangular-shaped opening  80  substantially prevents relative rotation between the lock member  26  and the second connector member  24 . 
     In the illustrated embodiment, the lock member  26  includes at least one axially-extending projection portion  82  defining a rod bearing surface  84  facing a direction along the rotational axis R and intersecting and overlapping a portion of the rod-receiving passage  60  of the second connector member  24 . ( FIGS. 1 and 4 ). The lock member  26  further includes an opposite axially-facing interface surface  86  facing the axially-facing interface surface  46  of the first connector member  22 . As shown in  FIG. 14 , the lock member  26  may be provided with a pair of axially-extending projections  82   a ,  82   b  arranged on opposite sides of the rotational axis R which define a pair of rod bearing surface  84   a ,  84   b . In the illustrated embodiment, the rod bearing surface  84 ,  84   a ,  84   b  is substantially flat and planar, with the flat/planar rod bearing surface extending from an upper portion of the lock member  26  to a lower portion of the lock member  26  and across the rotational axis R. ( FIGS. 3 ,  14  and  14 ). In one embodiment, the flat/planar rod bearing surface  84 ,  84   a ,  84   b  is generally symmetrical relative to the rotational axis R. However, other embodiments are also contemplated. Additionally, as shown in  FIGS. 1 and 4 , when the lock member  26  is assembled with the second connector member  24 , the rod bearing surfaces  84   a ,  84   b  are arranged on either side of the rod-receiving passage  60  and intersect and overlap a portion of the rod-receiving passage  60 , the purpose of which will be discussed below. In a further embodiment, the rod bearing surfaces  84   a ,  84   b  each have an angled configuration defining an angle θ relative to the axially-facing interface surface  86 . In the illustrated embodiment, the rod bearing surfaces  84   a ,  84   b  each define an angle θ relative to the axially-facing interface surface  86  of approximately 14 degrees. However, other angles θ are also contemplated as falling within the scope of the present invention. 
     In the illustrated embodiment, the axially-facing interface surface  86  of the lock member  26  includes interengagement structures  88 . In one embodiment, the interengagement structures  88  comprise a number of radially-extending splines and grooves positioned about the opening  80 . In the illustrated embodiment, the radially-extending splines and grooves  88  are positioned entirely about the opening  80 . However, it should be understood that the radially-extending splines and grooves  88  may instead be positioned about only a portion of the opening  80 . Additionally, although the illustrated embodiment of the invention depicts the interengagement structures  88  as radially-extending splines and grooves, it should be understood that other configurations of interengagement structures are also contemplated for use in association with the present invention. As shown in  FIGS. 1 and 4 , the interface surface  86  of the lock member  26  is positioned in oppositely-facing relation relative to the interface surface  46  of the first connector member  22 . Additionally, as will be discussed below, the radially-extending splines and grooves  88  of the lock member  26  may be selectively interengaged with the radially-extending splines and grooves  52  of the first connector member  22  in an interdigitating manner to selectively prevent relative rotation between the lock member  26  and the first connect member  22 , which in turn prevents relative rotational movement between the first and second connector members  22 ,  24  about the rotational axis R. 
     Referring now to  FIGS. 16 and 17 , shown therein are additional details regarding the retainer member  28 . As indicated above, the retainer member  28  is engaged with the first and second connector members  22 ,  24  and is configured to maintain rotational engagement between the first and second connector members  22 ,  24 . In the illustrated embodiment of the invention, the retainer member  28  is configured as a clip having a spring-like configuration and including a base portion  90  having opposite end portions  92   a ,  92   b , and projecting portions or lobes  94   a ,  94   b  extending from the base portion  90  and defining rounded end surfaces  96   a ,  96   b  and tapered side surfaces  98   a ,  98   b . Although a particular embodiment of the retainer member  28  has been illustrated and described herein, it should be understood that other types and configurations of the retainer member  28  are also contemplated. 
     As shown in  FIG. 2 , subsequent to positioning of the axial shaft  64  of the second connector member  24  within the axial opening  44  in the first connector member  22  and expansion of the enlarged flange portions  70  within the undercut region  50 , the retainer member  28  is inserted into the axial slot  74  defined by the axial shaft  64  of the second connector member  24  in a direction generally along the rotational axis R. As the retainer member  28  is axially displaced along the slot  74 , the rounded outer surfaces  96   a ,  96   b  of the lobes  94   a ,  94   b  are compressed against the tapered end surfaces  48  surrounding the axial passage  44  in the first connector member  22 , which in turn results in the lobes  94   a ,  94   b  being elastically and resiliently compressed toward one another to a reduced transverse profile to allow passage of the lobes  94   a ,  94   b  into and through the axial opening  44  to a position adjacent the undercut region  50 . 
     Once the lobes  94   a ,  94   b  are positioned adjacent the undercut region  50 , the lobes  94   a ,  94   b  are resiliently expanded back toward their original configuration wherein the lobes  94   a ,  94   b  are outwardly expanded into the undercut region  50  to securely engage the retainer member  28  with the first connector member  22 . In a specific embodiment, the retainer member  28  has a spring-like configuration to allow the lobes  94   a ,  94   b  to be elastically and resiliently compressed to the reduced transverse profile to allow axial insertion into the axial opening  44 , and to then allow the lobes  94   a ,  94   b  to be resiliently expanded into the undercut region  50 . Once properly engaged with the first connector member  22 , the retainer member  28  prevents the elastically resilient leg portions  76   a ,  76   b  of the axial shaft  64  from being compressed toward one another to a reduced profile configuration, thereby maintaining rotational engagement of the axial shaft  64  of the second connector member  24  within the axial opening  44  of the first connector member  22 . However, it should be understood that the retainer member  28  still allows relative rotational movement between the connector members  22 ,  24  about the rotational axis R. 
     Having described the various elements and features associated with the adjustable connector  20 , reference will now be made to use and operation of the adjustable connector  20  according to one embodiment of the present invention. As indicated above, the adjustable connector  20  is configured such that the first and second connector members  22 ,  24  are provisionally engaged to one another in a manner that allows relative rotational movement between the first and second connector members  22 ,  24  about the rotation axis R. As also indicated above, the spinal rod R 1  may be laterally inserted into the rod-receiving passage  40  of the first connector member  22  via the lateral openings  41 , and the spinal rod R 2  may be axially inserted into the rod-receiving passage  60  of the second connector member  24 . Once the spinal rods R 1 , R 2  are inserted into the rod-receiving passages  40 ,  60 , the sets screws  32 ,  34  are threaded into the threaded apertures  42  and  62 , respectively, in the first and second connector members  22 ,  24 . 
     As shown in  FIG. 3 , threading of the set screw  32  through the aperture  42  at least partially closes off the lateral opening  41  to initially retain the spinal rod R 1  within the passage  40 . Further displacement of the set screw  32  along the transverse axis T 1  urges the spinal rod R 1  in a lateral direction relative to the transverse axis T 1  and into abutment against the rod-engaging surface  43  of the passage  40 . Compression of the spinal rod R 1  against the rod-engaging surface  43  secures the spinal rod R 1  within the passage  40  to substantially prevent further axial or rotational movement of the spinal rod R 1  relative to the first connector member  22 . The set screw  34  is initially threaded into the aperture  62  in the second connector member  24 , but initially not into tight engagement with the second spinal rod R 2 . As illustrated in  FIG. 18 , the angular orientation of the first spinal rod R 1  relative to the second spinal rod R 2  may then be variably adjusted to a desired angular orientation via rotation of the first connector member  22  relative to the second connector member  24  about the rotational axis R. It should be understood that adjustment of the angular orientation of the first spinal rod R 1  relative to the second spinal rod R 2  via rotation of the first connector member  22  relative to the second connector member  24  may be accomplished during an operative procedure such as, for example, during an osteotomy procedure, during a spinal stabilization procedure, or during other surgical procedures that would occur to those having ordinary skill in the art. 
     Once the select angular orientation between the first and second spinal rods R 1 , R 2  (and the first and second longitudinal axes L 1 , L 2 ) has been achieved, the set screw  34  is driven further into the aperture  62  along the transverse axis T 2  and into compressing engagement with the spinal rod R 2 . The set screw  34  urges the spinal rod R 2  into abutting engagement against the rod bearing surfaces  84   a ,  84   b  of the lock member  26 , which in turn axially urges the lock member  26  toward the first connector member  22  in a direction along the rotation axis R, and which also pulls the first connector member  22  away from the second connector member  24  to compress an axially-facing surface or shoulder  71  defined by the enlarged annular flange  70  of the shaft  72  ( FIG. 12 ) against an opposing axially-facing surface or shoulder  51  defined by the undercut region  50  of the axial opening  44  ( FIG. 9 ). 
     Displacement of the lock member  26  toward the first connector member  22  compresses the interface surface  86  of the lock member  26  into engagement against the interface surface  46  of the first connector member  22 , which in turn results in intermeshing or interdigitating engagement between the radially-extending splines and grooves  88  of lock member  26  and the radially-extending splines and grooves  52  defined by the first connector member  22 . Interdigitating or intermeshing engagement between the radially-extending splines and grooves  52 ,  88  selectively prevents relative rotational movement between the lock member  26  and the first connector member  22 . Since the lock member  26  and the second connector member  24  are non-rotatably coupled to one another, selectively preventing relative rotational movement between the lock member  26  and the first connector member  22  correspondingly prevents relative rotational movement between the first and second connector members  22  and  24 , thereby locking the spinal rods R 1 , R 2  at a select angular orientation relative to one another. Additionally, compression of the spinal rod R 2  between the set screw  34  and the rod bearing surfaces  84   a ,  84   b  of the lock member  26  secures the spinal rod R 2  within the rod-receiving passage  60  to substantially prevent further axial or rotational movement of the spinal rod R 2  relative to the second connector member  24 . At this point, the spinal rods R 1 , R 2  are each secured within the rod-receiving passages  40 ,  60  of the first and second connector members  22 ,  24 , and the first and second connector members  22 ,  24  are locked at a select rotational position relative to one another about the rotational axis R, which in turn locks the spinal rods R 1 , R 2  at a select angular orientation relative to one another. 
     In the illustrated embodiment of the adjustable connector  20 , the set screw  34  serves two functions. First, the set screw  34  compresses the spinal rod R 2  into abutting engagement against the rod bearing surfaces  84   a ,  84   b  of the lock member  26  to lock the spinal rod R 2  within the rod-receiving passage  60  to substantially prevent further axial or rotational movement of the spinal rod R 2  within the passage  60 . Second, the set screw  34  axially urges the lock member  26  toward the first connector member  22  (via the spinal rod R 2 ) to provide intermeshing or interdigitating engagement between the splines  88  of lock member  26  and the splines  52  of the first connector member  22 , thereby substantially preventing relative rotational movement between the first and second connector members  22  and  24 . However, it should be understood that one or more additional compression members or set screws may be provided to axially engage the lock member  26  with the first connector member  22  to substantially prevent relative rotational movement between the first and second connector members  22  and  24  or other locking or compressive components. For example, a third set screw (not shown) may be provided which is threaded through a passage (not shown) in the first connector member  22  and into secure engagement with the axial shaft  64  of the second connector member  24  to substantially prevent relative rotational movement between the first and second connector members  22  and  24 . Additionally, a third set screw may be used to urge the connector members  22 ,  24  into secure engagement with one another and/or to securely engage other types and configurations of lock members between the connector members  22 ,  24  to substantially prevent relative rotational movement therebetween. 
     Referring to  FIG. 19 , shown therein is an adjustable connector  100  according to yet another form of the present invention. In many respects, the adjustable connector  100  is structurally and functionally similar to the adjustable connectors  20  illustrated and described above. Specifically, the adjustable connector  100  generally includes a first connector member or block  122  configured for coupling with a first spinal rod R 1  extending generally along a longitudinal axis L 1 , a second connector member or block  124  configured for coupling with second spinal rod R 2  extending generally along a longitudinal axis L 2 , a lock member  126  positioned between the first and second connector members  122 ,  124 . However, unlike the adjustable connector  20  which includes a single set screw  32 ,  34  associated with each of the connector members  22 ,  24 , the adjustable connector  100  includes a first pair of set screws  132   a ,  132   b  associated the first connector member  122 , and a second pair of set screws  134   a ,  134   b  associated the second connector member  124 . 
     As should be appreciated, the adjustable connector  100  is configured to permit relative rotational movement between the first and second connector members  122 ,  124  about a rotational axis R to allow variation in the angular orientation of the first spinal rod R 1  relative to the second spinal rod R 2 , and more specifically between the longitudinal axes L 1 , L 2  of the spinal rods. Additionally, unlike the adjustable connector  20  illustrated and described above wherein the first connector member  22  includes a rod-receiving passage  40  defining a lateral opening  41  for lateral receipt of the spinal rod R 1 , each of the rod-receiving passages defined by the connector members  122 ,  124  has a closed configuration such that the spinal rods R 1 , R 2  are both axially inserted into the rod-receiving passages. 
     Once the spinal rods R 1 , R 2  are inserted into the rod-receiving passages, the first pair of set screws  132   a ,  132   b  are tightened to secure the spinal rods R 1  within the rod-receiving passage of the first connector member  122 , and the second pair of set screws  134   a ,  134   b  are tightened to secure the spinal rods R 2  within the rod-receiving passage of the second connector member  124 . Additionally, similar to operation of the adjustable connector  20 , tightening of either pair of the set screws  132   a ,  132   b  and  134   a ,  134   b  may further serve to axially urge the lock member  126  toward the first connector member  122  in a direction along the rotation axis R so as to intermeshingly engage radially-extending splines and grooves associated with the lock member  126  with radially-extending splines and grooves defined by the first connector member  122 . Such intermeshing engagement selectively prevents relative rotational movement between the lock member  126  and the first connector member  122 , which in turn selectively prevents relative rotational movement between the first and second connector members  122 ,  124  to thereby lock the spinal rods R 1 , R 2  at a select angular orientation relative to one another. 
     Referring to  FIG. 20 , shown therein is an adjustable connector  200  according to another form of the present invention. In many respects, the adjustable connector  200  is structurally and functionally similar to the adjustable connector  20  illustrated and described above. Specifically, the adjustable connector  200  generally includes a first connector member or block  222  configured for coupling with a first spinal rod R 1  (shown in phantom), and a second connector member or block  224  configured for coupling with second spinal rod R 2  (shown in phantom). The adjustable connector  200  also includes a lock member  226  at least partially positioned between the first and second connector members  222 ,  224  and configured to aid in selectively preventing relative rotational movement between the first and second connector members  222 ,  224  about a rotational axis R, and may also be provided with a retainer member (not shown) configured to maintain rotational engagement between the first and second connector members  222 ,  224 . The adjustable connector  200  also includes a first compression member or set screw  232  extending generally along a transverse axis T 1  and configured to engage the first spinal rod R 1  with the first connector member  222 , and a second compression member or set screw  234  extending generally along a transverse axis T 2  and configured to engage the second spinal rod R 2  with the second connector member  224 . 
     The first connector member  222  includes a first passage  240  sized and configured to receive the first spinal rod R 1  therein, and the second connector member  224  includes a second passage  260  sized and configured to receive a portion of the second spinal rod R 2  therein. Additionally, like the adjustable connector  20 , the rod-receiving passage  240  defined by the first connector member  222  has an open configuration defining a lateral opening  241  sized to laterally receive the spinal rod R 1  therethrough such that the spinal rod R 1  may be laterally or transversely inserted into the passage  240 . However, unlike the adjustable connector  20 , the rod-receiving passage  260  defined by the second connector member  224  has an open configuration defining a transverse opening  261  sized to laterally receive the spinal rod R 2  therethrough such that the spinal rod R 2  may be transversely inserted into the passage  260 . Specifically, the rod-receiving passage  260  has a U-shaped configuration and the transverse opening  261  opens in a direction toward the top of the connector member  240  to allow the spinal rod R 2  to be top-loaded into the passage  260  in a direction transverse or normal to the longitudinal axis of the spinal rod R 2 . However, it should be understood that the opening  261  may open in other directions to allow side loading, bottom loading, or angled transverse loading of the spinal rod R 2  into the rod-receiving passage  260 . Additionally, a first set screw  232  is threaded into a threaded aperture in the connector member  222  to close off at least a portion of the lateral opening  241  to capture the spinal rod R 1  within the passage  240 . Additionally, a second set screw  234  is threaded into a threaded aperture in the connector member  224  to entirely close off the transverse opening  261  to capture the spinal rod R 2  within the rod-receiving passage  260 . 
     Referring to  FIGS. 21-23 , shown therein is an adjustable connector  300  according to a further form of the present invention for interconnecting elongate rod members R 1 , R 2  (shown in phantom in  FIG. 23 ) or other types and configurations of spinal implants at variable angular orientations relative to one another. The adjustable connector  300  generally includes a first connector member or block  322  configured for coupling with a first spinal rod R 1  extending generally along a longitudinal axis L 1 , and a second connector member or block  324  configured for coupling with a second spinal rod R 2  extending generally along a longitudinal axis L 2 . The adjustable connector  300  also includes a first lock member  326  associated with the first connector member  322  and a second lock member  327  associated with the second connector member  324 , and a retainer member  328  engaged between the first and second connector members  322 ,  324 . As will be discussed below, the first and second lock members  326 ,  327  are configured to aid in selectively preventing relative rotational movement between the first and second connector members  322 ,  324  about a rotational axis R. As will also be discussed below, the retainer member  328  is configured to maintain rotational engagement between the first and second connector members  322 ,  324 . 
     Unlike the adjustable connector  20  illustrated and described above, the adjustable connector  300  includes a single compression member (not shown) extending generally along a transverse axis T and configured to engage the first spinal rod R 1  with the first connector member  322 . Additionally, the single compression member also engages the second spinal rod R 2  with the second connector member  324 , and further engages the first lock member  326  with the second lock member  327  to selectively prevent relative rotational movement between the first and second connector members  322 ,  324  about a rotational axis R, the details of which will be set forth below. In one embodiment, the single compression member may be configured similar to the set screw  34  illustrated and described above with regard to the adjustable connector  20 . However, it should be understood that other types and configurations of compression members are also contemplated. 
     The first connector member  322  includes a first passage  340  sized and configured to receive the first spinal rod R 1  therein, and the second connector member  324  includes a second passage  360  sized and configured to receive a portion of the second spinal rod R 2  therein. In the illustrated embodiment of the adjustable connector  300 , each of the rod-receiving passages  340 ,  360  has a closed configuration such that the spinal rods R 1 , R 2  are axially inserted into the rod-receiving passages  340 ,  360 . However, it should be understood that either or both of the rod-receiving passages  340 ,  360  may alternatively have an open configuration such that the spinal rods R 1 , R 2  may be laterally or transversely inserted into the passages  340 ,  360 . Additionally, the first connector member  322  includes an aperture  342  communicating with the rod-receiving passage  340  and extending generally along a transverse axis T for receiving the compression member therethrough. In the illustrated embodiment, the transverse axis T is arranged substantially normal or perpendicular to the rotational axis R. However, other positions and orientations of the aperture  342  and the transverse axis T are also contemplated. In the illustrated embodiment, the compression member is configured as a set screw, and the aperture  342  in the first connector member  322  is internally threaded so as to threadingly receive the set screw therethrough. However, it should be understood that other types and configurations of the compression member are also contemplated as falling within the scope of the present invention, including a non-threaded compression member. 
     In the illustrated embodiment, the closed rod-receiving passage  340  of the connector member  322  has an elongate slot-like configuration extending along an axis A that is arranged at an oblique angle relative to both the rotational axis R and the transverse axis T. The first connector member  322  includes an opening or recess  344  arranged generally along the rotational axis R. As will be discussed in greater detail below, the axial opening  344  is sized and configured to receive a shaft or stem portion  364  extending from the second connector member  324  and which is also arranged generally along the rotational axis R. The axial opening  344  and the axial shaft  364  cooperate with one another to permit rotation of the first connector member  322  relative to the second connector member  324  about the rotational axis R. Although the illustrated embodiment of the connector  300  provides the first connector member  322  with the axial opening  344  and the second connector member  324  with the axial shaft  364 , it should be understood that in other embodiments, the first connector member  322  may be provided with the axial shaft  364  and the second connector member  324  may be provided with the axial opening  344 . 
     In one embodiment, the axial opening  344  in the first connector member  322  has a circular configuration and includes an enlarged cross sectional portion or undercut region  350  that may be provided in the form of an annular groove, the purpose of which will be discussed below. In the illustrated embodiment of the adjustable connector  300 , the first connector member  322  also includes an axial stem portion  354  arranged generally along the rotational axis R, with the axial opening  344  extending through the axial stem portion  354  and into communication with the rod-receiving passage  340 . Additionally, the axial stem portion  354  has a generally rectangular configuration including flattened or truncated surfaces  355 . However, it should be understood that other shapes and configurations of the axial stem portion  354  are also contemplated. Furthermore, the axial stem portion  354  may be provided with grooves or recesses  356  defined along opposite sides of the axial stem portion  354  for receipt of a material or substance such as, for example, a silicone adhesive material (not shown). 
     In the illustrated embodiment, the closed rod-receiving passage  360  of the connector member  324  has a circular configuration substantially corresponding to the outer cross section of the spinal rod R 2 . Additionally, the rod-receiving passage  360  may be provided with an undercut region or annular groove  361  to provide at least two annular lines of contact between the connector member  324  and the spinal rod R 2  to facilitate more secure engagement with the spinal rod R 2 . In the illustrated embodiment, the second connector member  324  includes a base portion  362  and a shaft or stem portion  364  extending therefrom generally along the rotational axis R and sized and configured for rotational engagement within the axial opening  344  in the first connector member  322  to permit rotation of the first connector member  322  relative to the second connector member  324  about the rotational axis R. In the illustrated embodiment, the base portion  362  of the connector member  324  has a generally rectangular configuration including flattened or truncated surfaces  363 . However, other shapes and configurations of the base portion  362  are also contemplated. The axial shaft  364  of the second connector member  324  includes an annular groove or recess  366  extending at least partially thereabout. The annular groove  366  is located for positioning adjacent the undercut region  350  of the axial opening  344  in the first connector member  322  when the axial shaft  364  is positioned within the axial opening  344 . 
     In the illustrated embodiment, the retainer member  328  is in the form of an elastically resilient C-shaped clip or snap ring and includes an axially-facing tapered surface  329 . As shown in  FIG. 23 , prior to positioning of the axial shaft  364  of the second connector member  324  within the axial opening  344  in the first connector member  322 , the C-shaped clip  328  is positioned within the annular groove  366  of the axial shaft  364 . As the shaft  364  is inserted into the axial opening  344  in the first connector member  322 , the tapered outer surface  329  of the C-shaped clip  328  is compressed against an axially-facing surface of the stem portion  354 , which in turn inwardly and elastically deforms the clip  328  to a reduced outer profile sized for axial insertion into the axial opening  344 . Once the C-shaped clip  328  is positioned in alignment with the undercut region  350 , the C-shaped clip  328  is allowed to resiliently snap back toward its original configuration wherein the clip  328  is outwardly expanded into the undercut region  350 . Positioning of the retainer clip  328  within the annular groove  366  of the axial shaft  364  and the undercut region  350  of the axial opening  344  maintains the first and second connector members  322 ,  324  in rotational engagement with one another. However, it should be understood that the retainer clip  328  still allows relative rotational movement between the connector members  322 ,  324  about the rotational axis R. Additionally, although a particular embodiment of the retainer member  328  has been illustrated and described herein, it should be understood that other configurations of the retainer member  328  are also contemplated. 
     In the illustrated embodiment, the first lock member  326  has disc or washer-like configuration defining an opening  380  extending generally along the rotational axis R and sized and shaped to receive the axial stem portion  354  of the first connector member  322  therethrough. In the illustrated embodiment, the opening  380  has a shape that corresponds to that of the axial stem portion  354 . In one embodiment, the opening  380  has a generally rectangular configuration including flattened or truncated surfaces. However, it should be understood that other shapes and configurations of the opening  380  are also contemplated. Additionally, it should be appreciated that positioning of the rectangular-shaped axial stem portion  354  within the rectangular-shaped opening  380  substantially prevents relative rotation between the first lock member  326  and the first connector member  322 . The first lock member  326  also includes a pair of axially-extending projections  382  arranged on opposite sides of the rotational axis R and defining a pair of rod bearing surface  384  facing a direction along the rotational axis R and intersecting and overlapping a portion of the rod-receiving passage  340  of the connector member  322 . The lock member  326  further includes an opposite axially-facing interface surface  386  which faces an axially-facing interface surface  396  of the second lock member  327 . Additionally, the rod bearing surfaces  384  are provided with an angled configuration defining an oblique relative to the axially-facing interface surface  386 . 
     In the illustrated embodiment, the axially-facing interface surface  386  of the first lock member  326  includes interengagement structures  388 . In one embodiment, the interengagement structures  388  comprise a number of radially-extending splines and grooves positioned about the rectangular-shaped opening  380 . In the illustrated embodiment, the radially-extending splines and grooves  388  are positioned entirely about the opening  380 . However, it should be understood that the radially-extending splines and grooves  388  may instead be positioned about only a portion of the opening  380 . Additionally, although the illustrated embodiment of the first lock member  326  depicts the interengagement structures  388  as radially-extending splines and grooves, it should be understood that other configurations of interengagement structures are also contemplated for use in association with the present invention. 
     In the illustrated embodiment, the second lock member  327  also has disc or washer-like configuration defining an opening  390  extending generally along the rotational axis R and sized and shaped to receive the base portion  362  of the second connector member  324  therethrough. In the illustrated embodiment, the opening  390  has a shape that corresponds to that of the base portion  362 . In one embodiment, the opening  390  has a generally rectangular configuration including flattened or truncated surfaces  391 . However, it should be understood that other shapes and configurations of the opening  390  are also contemplated. Additionally, it should be appreciated that positioning of the rectangular-shaped base portion  362  within the rectangular-shaped opening  390  substantially prevents relative rotation between the second lock member  327  and the second connector member  324 . The second lock member  327  also includes a rod-receiving groove  392  arranged on one side of the lock member  327  and generally aligned with the rod-receiving passage  360  of the connector member  324 . The second lock member  327  further includes an opposite axially-facing interface surface  396  which faces the axially-facing interface surface  386  of the first lock member  326 . Additionally, the rod-receiving groove  392  defines a rod bearing surface  394  for engagement with the spinal rod R 2 . 
     In the illustrated embodiment of the second lock member  327 , the axially-facing interface surface  396  of the second lock member  327  includes interengagement structures  398 . In one embodiment, the interengagement structures  398  comprise a number of radially-extending splines and grooves positioned about the rectangular-shaped opening  390 . In the illustrated embodiment, the radially-extending splines and grooves  398  are positioned entirely about the opening  390 . However, it should be understood that the radially-extending splines and grooves  398  may instead be positioned about only a portion of the opening  390 . Additionally, as will be discussed below, the radially-extending splines and grooves  388 ,  398  of the first and second lock members  326 ,  327  are selectively interengaged with one another in an interdigitating manner to substantially prevent relative rotation between the first and second lock members  326 ,  327 , which in turn substantially prevents relative rotational between the first and second connector members  322 ,  324 . 
     Having described various elements and features associated with the adjustable connector  300 , reference will now be made to use and operation of the adjustable connector  300  according to one embodiment of the present invention. As indicated above, the adjustable connector  400  is configured such that the first and second connector members  322 ,  324  are engaged to one another in a manner allowing relative rotational movement between the first and second connector members  322 ,  324  about the rotation axis R. As also indicated above, the spinal rod R 1  may be axially inserted into the closed rod-receiving passage  340  of the first connector member  322 , and the spinal rod R 2  may be axially inserted into the closed rod-receiving passage  360  of the second connector member  324 . The angular orientation of the first spinal rod R 1  relative to the second spinal rod R 2  is then adjusted to a desired angular orientation via rotation of the first connector member  322  relative to the second connector member  324  about the rotational axis R. Once the select angular orientation between the first and second spinal rods R 1 , R 2  has been achieved, the set screw is driven through the aperture  342  along the transverse axis T and into compressing engagement with the spinal rod R 1 . The set screw urges the spinal rod R 1  into abutting engagement against the rod bearing surfaces  384  of the first lock member  326 , which result in axial displacement of the first lock member  326  into engagement with the second lock member  327 , which in turn axially displaces the second lock member  327  toward the second connector member  324  and into compressing engagement with the second spinal rod R 2 . 
     Threading the set screw through the aperture  342  in the connector member  322  serves multiple functions. First, tightening the set screw against the spinal rod R 1  compresses the spinal rod R 1  into abutting engagement against the rod bearing surfaces  384  of the first lock member  326  to thereby prevent further axial or rotational movement of the spinal rod R 1  with the rod-receiving passage  340 . Second, tightening the set screw also compresses the splined interface surface  386  of the first lock member  326  into intermeshing or interdigitating engagement with the splined interface surface  396  of the second lock member  327 , which in turn selectively prevents relative rotational movement between the lock members  326  and  327  and relative rotational movement between the first and second connector members  322 ,  324 , thereby locking the spinal rods R 1 , R 2  at a select angular orientation relative to one another. Third, tightening the set screw also compresses the rod bearing surface  394  of the second lock member  327  against the spinal rod R 2 , which in turn compressingly engages the spinal rod R 2  against an inner rod-engaging surface defined by the rod-receiving passage  360  of the second connector member  324  to substantially prevent further axial or rotational movement of the spinal rod R 2  relative to the second connector member  324 . Accordingly, a single compression member is used to secure the spinal rods R 1 , R 2  within the rod-receiving passages  340 ,  360  of the first and second connector members  322 ,  324 , and to lock the first and second connector members  322 ,  324  at a select rotational position relative to one another about the rotational axis R, which in turn locks the spinal rods R 1 , R 2  at a select angular orientation relative to one another. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being 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.