Abstract:
A spinal rod connector is disclosed that allows end-to-end connection of at least two spinal rods. The connector may allow for angular adjustment in the construct which is associated with the patient&#39;s anatomy. Percutaneous length adjustment of the spinal rods may be available with visual assessment of the length of the rods via viewing windows on the connector. A locking mechanism may be used to fix a determined angle of the connector dependent upon the anatomy of the patient. The angle may be adjusted if necessary during a subsequent procedure.

Description:
BACKGROUND 
     The present application relates generally to the field of spinal implant systems, and in particular, to a variable angle growth rod connector that may be implanted as part of a growth rod fusionless system. 
     The spine is subject to various pathologies that comprise its load bearing and support capabilities. Such pathologies of the spine include, for example, degenerative disease, the effect of tumors and, of course, fractures and dislocations attributable to physical trauma. In the treatment of diseases, malformations or injuries affecting spinal motion segments (which include two or more adjacent vertebrae and the disc tissue for disc space there-between), and especially those affecting disc tissue, it has long been known to remove some or all of a degenerated, ruptured or otherwise failing disc. It is also known that artificial disc, fusion implants, or other interbody devices can be placed into the disc space after disc material removal. External stabilization of spinal segments alone or in combination with interbody devices also provides advantages. Elongated rigid plates, rods and other external stabilization devices have been helpful in the stabilization and fixation of a spinal motion segment, in correcting abnormal curvatures and alignments of the spinal column, and for treatment of other conditions. 
     In spinal rod fixation procedures, bending the rod induces stress to the rod and decreases the fatigue strength of the material. In addition, the geometric and dimensional features of these rod systems and patient anatomy constrain the surgeon during surgery and prevent optimal placement and attachment along the spinal column. For example, elongated, one-piece rods can be difficult to bend and maneuver into position between the vertebral members along the spine which provides the surgeon with only limited options in sizing and selection of the rod system to be placed during surgery. A small child presents even more difficulties because of the growth patterns associated with the age of the child. Existing spinal implant systems and methods should accommodate for the various growth patterns as the child grows which can be typically handled by a growth rod fusionless system. 
     Thus, there is a need in the art for a growth rod fusionless system that can be used to accommodate the growth patterns and the various anatomies associated with the spine. 
     SUMMARY 
     The present application relates to connectors that may be implanted as part of a growth rod fusionless system. The connector may allow an angle to be set in the construct dependent on the patient&#39;s anatomy and where the connector is placed. The connector may also allow for a percutaneous length adjustment as the patient grows. A viewing feature in the connector may allow the surgeon to see how much rod is engaged in the connector to determine length adjustment capability. 
     In one embodiment, a spinal rod connector includes a first portion that may be adapted to receive a first spinal rod; a second portion that may be adapted to receive a second spinal rod; and a hinge portion that may connect the first and second portions end-to-end and allows an angle adjustment dependent upon the anatomy of the patient. The connector may allow the spinal rods to be joined end-to-end in a lengthwise orientation with both the capability to adjust and view the length of the rods. The hinge portion may include a locking mechanism that allows the first and second portions to be locked in the pre-determined angle and may allow for percutaneous angle adjustment. 
     In another embodiment, the hinge portion may include a hinge pin to allow angle adjustment and a locking fastener to lock the first and second portions in a pre-determined angle and may also allow for angle adjustment. Windows may be located in both the first and second portions to allow visual determinations of the length of rods that are needed for the construct. 
     In one embodiment, a system for connecting spinal rods in an end-to-end fashion includes first and second portions that are connected by a hinge pin. The system may allow end-to-end connection of two spinal rods whose lengths can be adjusted depending upon the anatomy of the patient. 
     Further features and advantages of the embodiments will become apparent to those skilled in the art in view of the detailed description of preferred embodiments which follows, when considered together with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view of a connector to connect first and second spinal rods according to one embodiment. 
         FIG. 2  is a perspective view of a connector according to one embodiment. 
         FIG. 3  is a schematic side view of a connector according to one embodiment. 
         FIG. 4  is a side view of a connector in an angular orientation according to one embodiment. 
         FIG. 5  is a side view of a connector in an angular orientation according to one embodiment. 
         FIG. 6  is a top view of a connector according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The present application is directed to a connector for connecting spinal rods.  FIG. 1  illustrates a schematic view of one embodiment of the connector  10  that includes a first member  20  connected to a second member  30  with a hinge  40 . The first member  20  is sized to receive a first spinal rod  100 , and the second member  30  is sized to receive a second spinal rod  101 . Hinge  40  provides for positioning the members  20 ,  30  and rods  100 ,  101  at a variety of angular orientations with centerlines X, Y of the rods  100 ,  101  forming an angle α. The angle α may vary for use in a first spinal application such as a lordotic section of the spine, and a second positioning for use in a second application such as a kyphotic section of the spine. 
       FIG. 2  illustrates one embodiment of the connector  10  comprising the first and second members  20 ,  30  connected by a hinge  40 . First member  20  includes an elongated shape with a first end  21  opposite from the second end  22 . A bore  23  extends inward from the first end  21  along a length of the first member  20 . Bore  23  may include a variety of sectional shapes, including circular as illustrated in  FIG. 2 . The bore  23  may extend the entire length, or may terminate at a point in proximity to the second end  22 . Bore  23  is positioned within an interior of the first member  20  and is enclosed by the sides of the member  20 . In the embodiment of  FIG. 2 , first member  20  includes a first side  24  and opposing second and third sides  25 ,  26 . The first side  24  is substantially flat, and is substantially perpendicular to the second and third sides  25 ,  26 . In one embodiment, the first member  20  is cylindrical with the first side  24  being substantially flat. 
     A window  27  extends inward into the bore  23  from the first side  24 . Window  27  provides for the physician to visual observe the positioning of the first rod  100  within the bore  23  as will be explained in detail below. Window  27  may include substantially smooth sidewalls. In the embodiment of  FIG. 2 , window  27  includes an elongated shape with a major axis and a minor axis. The major axis is substantially aligned with the bore  23 . 
     An opening  28  also extends inward into the bore  23  from the first side  24 . Opening  28  is threaded to receive a fastener  80  that connects the first member  20  to the first rod  100 . In this embodiment, opening  28  is positioned between the window  27  and the first end  21 . 
     The second member  30  shares many of the characteristics of the first member  20 . 
     Second member  30  includes an elongated shape that extends between a first end  31  and a second end  32 . A bore  33  is positioned within the second member  30  and extends inward from the first end  31  and may extend the entire length, or may terminate at a point inward from the second end  32 . Bore  33  may include a variety of sectional shapes, including circular. Second member  30  includes a first side  34  and opposing second and third sides  35 ,  36 . In this embodiment, the first side  34  is substantially flat and perpendicular to the second and third sides  35 ,  36 . In one embodiment, the second member  30  is cylindrical with the first side  34  being substantially flat. 
     A window  37  extends inward into the bore  33  from the first side  34  for the physician to visually observe the positioning of the second rod  101  within the bore  33 . Window  37  may include substantially smooth sidewalls. In the embodiment of  FIG. 2 , window  37  includes an elongated shape with a major axis and a minor axis. The major axis is substantially aligned with the bore  33 . 
     An opening  38  also extends inward into the bore  33  from the first side  34 . Opening  38  is threaded to receive a fastener  80  that connects the second member  30  to the first rod  101 . In this embodiment, opening  38  is positioned between the window  37  and the first end  31 . 
     A second opening  39  is positioned on the first side  34  and extends to the hinge  40 . The second opening  39  is threaded to receive a fastener  90  that engages with the hinge  40  and locks the angular orientation of the first and second members  20 ,  30 . As best illustrated in  FIG. 3 , opening  39  extends inward into the body  30  at an acute angle β relative to the bore  33 .  FIG. 3  also illustrates an embodiment with the window  27  and opening  28  being substantially perpendicular to bore  23  of the first member  20 , and window  37  and opening  38  being substantially perpendicular to bore  33  of the second member  30 . 
     Fasteners  80 ,  90  each include a body with exterior threads, a first end with a tool-receiving receptacle, and a second end with a contact surface. Contact surfaces on the fasteners  80  are configured to contact and engage with the spinal rods  100 ,  101 . Fastener  90  includes a contact surface that contacts and engages with the hinge  40 . Each of the fasteners  80 ,  90  may be substantially the same, or each may be different. In one embodiment, the contact surface  90  on the fastener includes splines that engage with splines that extend from the hinge  40 . 
     Hinge  40  extends through each of the first and second members  20 ,  30 . In one embodiment, hinge  40  is fixedly attached to the first member  20 , and movably attached to the second member  30 . In this manner, second member  30  may move relative to the first member  20  and hinge  40  prior to securing the positioning with the fastener  90 . 
     The hinge  40  provides for selectively positioning the angle formed between the first and second members  20 ,  30 .  FIG. 4  illustrates the first rod  100  positioned within the bore  23  of the first member  20 , and the second rod  101  positioned within the bore  33  of the second member  30 . The first and second members  20 ,  30  are positioned at an angular position about the hinge  40  to form an angle α formed between the centerlines X, Y of the rods  100 ,  101 .  FIG. 5  illustrates the connector  10  in a second orientation with the first and second members  20 ,  30  being relatively moved to increase the angle α. The connector  10  may be used in a variety of different contexts because of the ability to vary the angle α between an angle such as illustrated in  FIG. 4  and larger angle in  FIG. 5 . The connector  10  may be used in a first context as illustrated in  FIG. 4 , such as with a lordotic section of the spine. The same connector  10  may be adjusted and used in a second context as illustrated in  FIG. 5 , such as a kyphotic section of the spine. Further, the angle α may be adjusted to accommodate the various spinal locations of the connector  10 . In one embodiment, the angle α may range from between about 60° to about 120°. 
       FIG. 6  illustrates one embodiment of a top view of the connector  10 . A centerline C extends through each of the first and second members  20 ,  30  and aligns with the bores  23 ,  33 . Each of the windows  27 ,  37 , and openings  28 ,  38 ,  39  are substantially centered along the centerline C. The bores  23 ,  33  are positioned to orient the rods  100 ,  101  within a common plane, and in an end-to-end orientation. A physician is able to access each of the windows  27 ,  37  and openings  28 ,  38 ,  39  from a single direction to facilitate adjustment of the connector  10 . In one embodiment, connector  10  is positioned within the patient such that the windows  27 ,  37  and openings  28 ,  38 ,  39  face outward. This positioning provides for the windows and openings to be accessed in a minimally invasive manner with only minor incisions in the patient necessary to access the connector  10 . In one embodiment, this positioning provides for the openings  28 ,  38 ,  39  to be accessed in a percutaneous procedure. 
     In one method of use, the first rod  100  is inserted within the first bore  23  of the first member  20 . The interior surface of the first bore  23  may be substantially smooth to facilitate insertion of the rod  100 . During insertion, the physician is able to look through the window  22  and visually observe the location of the rod  100  within the bore  23 . Once the rod  100  is axially positioned within the bore  23 , the fastener  80  within the opening  28  is tightened to contact the rod  100  and secure the axial location within the bore  23 . In a similar fashion, rod  101  is inserted into the second bore  33 . Again, the physician may be able to visually observe the axial movement of the rod  101  within the bore  33  through the window  37 . Once axially positioned, fastener  80  is tightened to within the opening  38  to contact and secure the rod  101 . 
     Once the rods  100 ,  101  are secured, the members  20 ,  30  are moved about the hinge  40  to the desired angle α. Once set, fastener  90  is tightened within the opening  39  to contact the hinge and secure the relative positions of the members  20 ,  30 . The connector  10  may be positioned relative to the vertebral members such that the first sides  24 ,  34  face in a direction that may be accessed in a subsequent, revision surgical procedure. The order of attachment of the rods  100 ,  101 , and securing the members  20 ,  30  at the desired angle α may vary. By way of example, the angle α may be set prior to attaching one or both rods  100 ,  101  within the members  20 ,  30 . 
     In some instances, a revision procedure is necessary to adjust the positions of one or both rods  100 ,  101 , and/or change the angle α. The revision procedure may be performed in a minimally-invasive manner because of the positioning of the fasteners  80 ,  90 . In one embodiment, the procedure is percutaneous with a small incision is made into the patient to access the fasteners  80 ,  90 . A tool is inserted into the incision to loosen the fasteners  80  and adjust the axial position of the rods  100 ,  101  as necessary. The physician may be able to view the position of the rods through the windows  27 ,  37 . Once positioned, fasteners  80  are tightened to contact the rods  100 ,  101  and lock the position. Likewise, a tool is inserted into the incision to loosen the fastener  90  and adjust the angular position if necessary. Once adjusted, fastener  90  is tightened to lock the angular position. 
       FIGS. 2 and 6  illustrate one embodiment with the first member  20  including a large window  27 , and second member  30  including a smaller window  37 . The size of the windows may vary depending upon the context of use and need for the physician to observe the position of the rods  100 ,  101 . In one embodiment, the windows  27 ,  37  are substantially identical. 
     In one embodiment, the cross-sectional shape of the bores  23 ,  33  are substantially circular. In other embodiment, the cross-sectional shape may vary such as but not limited to rectangular, polygonal, oval, and triangular. The bores  23 ,  33  may include the same shape and size, or may include different shapes and/or sizes. 
     One embodiment of a spinal rod connector is disclosed in U.S. patent application Ser. No. 11/093,487 herein incorporated by reference in its entirety. 
     Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc and are also not intended to be limiting. Like terms refer to like elements throughout the description. 
     As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise. 
     The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.