Patent Publication Number: US-2019183539-A1

Title: Implantable Connector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and benefit from under 35 U.S.C. § 120 to copending U.S. patent application Ser. No. 15/436,308, filed on Feb. 17, 2017, which claims priority to U.S. Provisional Application No. 62/296,260, filed Feb. 17, 2016, the entire contents of aforementioned applications are herein incorporated by reference in their entirety. 
    
    
     FIELD 
     The present disclosure is directed to methods and apparatus for implantable connection to a rod, such as a spinal rod. 
     BACKGROUND 
     Surgery, whether of the spine or other areas of the body, is often complex and routinely involves the need for highly experienced medical staff, in addition to well-designed and well-manufactured implants, made to exacting specifications. Often the implants take the form of various types of hardware. In the area of spinal fixation, for example, various spinal fixation devices have been developed in the art. Some examples of such fixation devices include spinal rods, plates, corpectomy cages, and intervertebral discs, to name but a few. Spinal fixation rods are fixation devices configured to fix adjacent vertebrae of a spine relative to each other. The rods provide stabilization of the spine till fusion occurs. The spinal fixation rods are often used in spinal surgeries to repair spinal abnormalities, whether related to injury or otherwise. The spinal rods are configured to attach to the vertebrae using, for example, anchoring devices like pedicle screws and hooks. 
     Patients often experience extreme and debilitating pain because of spinal column injuries or from spinal column disorders such as spondylolisthesis and scoliosis. Pain may be attributed to issues of the spine as related to degeneration, deformity, and/or injury. Often a typical course of treatment involves surgical spinal fixation utilizing spinal fixation rods that mechanically immobilize areas of the spine causing, ideally, the eventual fusion of the treated vertebrae. 
     Sometimes additional surgical procedures, known as revision surgeries, become necessary. Several causes exist for the need for revision surgeries. For example, pseudarthrosis (failure to achieve solid fusion) may have occurred, which can be due to various causes such as poor tissue healing, improper implant placement or securement, implant failure, or to patient-related factors. Sometimes revision surgeries are indicated even after successful initial surgeries, given that the function and shape of the spine can deteriorate with age. Also, after prolonged use, the spinal fixation rods may move or become dislodged or unstable, or even bend or break. 
     Revision surgery is also required to treat adjacent segment disease (“ASD”). Spinal fusion recipients may be at risk for developing ASD, a condition in which the motion segments adjacent to the fused vertebral segments experience higher rates of degeneration or deterioration due to an increase in vertebral loading, higher intradiscal pressures, increased range of motion, and increased facet motion. Treatment options for ASD begin with determining whether the primary fusion is intact. If so, then a revision surgery with a revision connector is a likely course of action. 
     When considering spinal fusion revision surgery options, a few revision connectors are known, such as the “Revere Addition Revision System” and the “Expedium Universal Connector”. However, these connectors suffer from various drawbacks. First, these prior connectors are difficult to connect to the spinal level above the targeted level. This may be due to scar tissue or fusion mass that has developed in the lateral “gutters” across the transverse process. Second, such connectors add significant profile to the implant, both laterally and in height. Increased height can cause problems post-surgery when patients can feel the implants under their skin. Sometimes this leads to deep superficial pain. Third, prior art revision connectors do not achieve adequate stability in-line with the primary rod. Fourth, some prior art connectors are not ideal for minimally invasive surgical implantation techniques. 
     What is needed is a universal revision connector that is easy to install, with minimal profile, and that can sit in-line, nearly in-line, and/or at desired angles with the primary fusion rod. The connector ideally minimizes the disruption of the previous fusion mass and limposes less violation of the scar tissue. The stabilization may be extended to the next level above or below the fusion. Additional benefit is also achieved with a connector that can be inserted percutaneously. Ideally, a connector is desired that is not only suitable for revision surgeries, but also for primary fusion surgeries. The present connector provides vast improvement over such existing revision connectors. 
     SUMMARY 
     The disclosure herein is directed to an apparatus, system, and method for use in primary or revision surgeries. The system or implantable connector system would typically include at least a rotational connector, a connector set screw, a connector rod, and a connector rod set screw in some embodiments. The rotational connector is inserted in a “twist and lock” fashion. 
     In some embodiments of the invention, for example, an implantable connector system may include a rotational connector. The rotational connector may have a first end and a second end. In some embodiments, the first end may be configured to rotate from a first orientation to a second orientation, wherein in the first orientation the rotational connector may be top loaded onto a head of an existing pedicle screw. In some embodiments, when in the second orientation the first end of the rotational connector may receive an outer surface of a primary fusion rod. The second end may include a receptacle in some embodiments. In various embodiments, the implantable connector system may include a revision rod. The revision rod may have a first end and a second end. The first end may be matingly received in the receptacle of the second end of the rotational connector. Moreover in some embodiments, the implantable connector system may include a connector set screw. The connector set screw may be configured to threadingly engage a set screw opening in the first end of the rotational connector. In various embodiments, the implantable connector system may include a revision rod screw such as a set screw. The revision rod set screw may be configured to threadingly engage a set screw opening in the second end of the rotational connector. 
     In some embodiments, the rotational connector may include a middle portion top loaded onto a head of an existing pedicle screw. In various embodiments, the rotational connector may include a bottom having a receiving slot configured to receive an existing pedicle screw and a primary fusion rod. Further in some embodiments, the receiving slot may be a vertical first slot intersecting a horizontal second slot. Moreover in some embodiments, the horizontal second slot may be substantially in line with the revision rod when the first end of the revision rod is matingly received in the receptacle of the second end of the rotational connector. In various embodiments, the first end of the revision rod and the receptacle of the second end of the rotational connector may be a ball-and-socket joint. In some embodiments, the first end of the revision rod and the receptacle of the second end of the rotational connector may each have corresponding vertical teeth positioning the revision rod at an angle relative to the rotational connector. Moreover, in various embodiments, the first end of the revision rod or the receptacle of the second end of the rotational connector may include one or more protrusions received in one or more channels of the other one of the first end of the revision rod or the receptacle of the second end of the rotational connector. 
     In various embodiments, an implantable connector system may include a revision rod. The revision rod may have a first end and a second end. In some embodiments, the implantable connector system may include a rotational connector. Moreover in some embodiments, the rotational connector may have a first end, a second end, and a middle portion connecting the first end and the second end. Further in some embodiments, the middle portion may have a through opening extending from a bottom of the rotational connector. In some embodiments, the rotational connector may have a bottom with a first slot extending inwardly to a second slot. In some embodiments, the second slot may be transverse to and intersects the first slot. In various embodiments, the second slot may extend into the first end of the rotational connector. In various embodiments, the implantable connector system may include at least one first set screw. The first set screw may threadingly engage the first end of the revision rod to the second end of the rotational connector. In various embodiments, the implantable connector system may include at least one second set screw. The second set screw may threadingly engage the first end of rotational connector and extend into the second slot in the first end of the rotational connector. 
     In addition, in various embodiments, the first end of the rotational connector may include a top member, a bottom member, and a side member interconnecting the top member to the bottom member. In some embodiments the top member, the bottom member, and the side member may define the second slot in the first end of the rotational connector. In some embodiments, the revision rod may be axially aligned with the second slot when the revision rod is coupled with the rotational connector. In various embodiments, the revision rod may not be axially aligned with the second slot when the revision rod is coupled with the rotational connector. Moreover in some embodiments, the revision rod and the rotational connector may be coupled by a ball-and-socket joint. In some embodiments, the second slot may extend into the second end of the rotational connector. In various embodiments, the revision rod may be spaced at a higher elevation than the second slot. 
     Other embodiments may include a method of implanting a rotational connector. In some embodiments the rotational connector may have a first end and a second end. In various embodiments, the method may include opening a first surgical site in a patient to access a primary fusion site. Moreover, in some embodiments, the primary fusion site may include a primary fusion rod having a longitudinal rod axis and a first end and a second end, and a pedicle screw engaged in a vertebra. The first end of the primary fusion rod may terminate at a first distance away from an outer surface of the pedicle screw measured in a first direction in some embodiments. Further in some embodiments, the first direction may be generally parallel to the longitudinal rod axis. In some embodiments, the method may include inserting the rotational connector in a first orientation through the first surgical site and onto the pedicle screw in a second direction, the second direction may be generally perpendicular to the first direction. In various embodiments, the first orientation may be disposed at an angle to the longitudinal rod axis. In some embodiments, the method may include rotating the rotational connector from the first orientation to a second orientation, wherein in the second orientation the first end of the rotational connector matingly receives therewithin the second end of the primary fusion rod. In some embodiments, the method may include inserting a set screw into the first end of the rotational connector to secure the rotational connector to the primary fusion rod. In various embodiments, the method may include inserting a first end of a revision rod into the second end of the rotational connector. In some embodiments, the method may include inserting a set screw into the second end of the rotational connector to secure the rotational connector to the revision rod. 
     In addition, in some embodiments, the step of rotating the rotational connector from the first orientation to the second orientation may include wherein in the second orientation the second end of the rotational connector matingly receives therewithin the first end of the primary fusion rod. In various embodiments, the method may include the step of positioning the revision rod at an angle relative to the second end of the rotational connector. Moreover, in various embodiments, the step of position the revision rod at the angle relative to the second end of the rotational connector may include spherical angulation. In some embodiments, the step of rotating the rotational connector from the first orientation to the second orientation may include rotating the rotational connector about a screw head of the pedicle screw after the pedicle screw is inserted into the rotational connector. In some embodiments, the method may include the step of axial alignment of the revision rod and the primary fusion rod. In some embodiments, the step of rotating the rotational connector from the first orientation to the second orientation may include rotating an acute angle between the first orientation and the second orientation. Further, in some embodiments the acute angle may be 30 degrees. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention 
         FIG. 1  is a top perspective view of an embodiment of a system. 
         FIG. 2  is a top perspective view of the rotational connector of  FIG. 1  illustrating top loading in a first orientation relative to a pedicle screw system. 
         FIG. 3  is a top perspective view of the rotational connector of  FIG. 1  illustrating a second orientation or neutral position relative to the pedicle screw system with the set screws engaging the primary fusion rod. 
         FIG. 4  is a top perspective view of the rotational connector of  FIG. 1  illustrating the top loading of an embodiment of the revision rod. 
         FIG. 5  is a top perspective view of the revision rod of  FIG. 4  illustrating an in-line position of the revision rod fastened by a set screw in the rotational connector. 
         FIG. 6  is a top perspective view of the rotational connector of  FIG. 1 . 
         FIG. 7  is a bottom perspective view of the rotational connector of  FIG. 6 . 
         FIG. 8  is a perspective view of the set screw of  FIG. 1  for securing the primary fusion rod. 
         FIG. 9  is a perspective view of the revision rod of  FIG. 1 . 
         FIG. 10  is a perspective view of the connector rod set screw of  FIG. 3  for securing the revision rod. 
         FIG. 11  is a top perspective view of another embodiment of a system, illustrating a rotational connector in a second orientation or neutral position relative to the pedicle screw system with a set screw engaging the primary fusion rod and a revision rod being top loaded onto the rotational connector. 
         FIG. 12  is a top view of the embodiment of  FIG. 11 , illustrating a set screw positioning the revision rod at an angle relative to the rotational connector and/or primary fusion rod. 
         FIG. 13  is a top perspective view of the rotational connector of  FIG. 11 . 
         FIG. 14  is a top view of the rotational connector of  FIG. 13 . 
         FIG. 15  is a perspective view of the set screw for the rotational connector of  FIG. 11  for engaging the primary fusion rod. 
         FIG. 16  is a bottom perspective view of the revision rod of  FIG. 11  for use with the rotational connector opposite the primary fusion rod. 
         FIG. 17  is a perspective view of the set screw for the revision rod of  FIG. 11 . 
         FIG. 18  is top perspective view third embodiment of a system engaging a pedicle screw system, illustrating the rotational connector in the second orientation with the set screw engaging the primary fusion rod removed. 
         FIG. 19  is top perspective view of the system of  FIG. 18  with the set screw of the ball-and-socket engagement of the rotational connector and revision rod exploded away therefrom. 
         FIG. 20  is a side view of the system of  FIG. 18 . 
         FIG. 21  is a side sectional view of the system of  FIG. 18  taken along line  21 - 21 . 
         FIG. 22  is a top perspective view of the rotational connector of  FIG. 18 . 
         FIG. 23  is a perspective view of the revision rod of  FIG. 18  for use with the rotational connector. 
         FIG. 24  is a perspective view of the set screw of  FIG. 18  for engaging the revision rod. 
         FIG. 25  is a bottom perspective view of a fourth embodiment of a rotational connector. 
         FIG. 26  is a side view of another embodiment of a system engaging a pedicle screw system. 
         FIG. 27  is a bottom view of the system engaging a pedicle screw system of  FIG. 26 . 
         FIG. 28  is a top perspective view of the system engaging a pedicle screw system of  FIG. 26  exploded away from each other. 
         FIG. 29  is a side view of  FIG. 28 . 
         FIG. 30  is a top perspective view of the rotational connector of  FIG. 26  in a first orientation relative to the pedicle screw system. 
         FIG. 31  is a top perspective view of the rotational connector of  FIG. 26  in a second orientation relative to the pedicle screw system illustrating the set screws engaging the primary fusion rod. 
         FIG. 32  is a top perspective view of the rotational connector of  FIG. 26  in a second orientation relative to the pedicle screw system illustrating the top loading of the revision rod. 
         FIG. 33  is a top perspective view of another embodiment of a system engaging a pedicle screw system. 
         FIG. 34  is a top perspective view of the system engaging a pedicle screw system of  FIG. 33  exploded away from each other. 
         FIG. 35  is a top view of the system engaging a pedicle screw system of  FIG. 33 . 
         FIG. 36  is a side view of the system engaging a pedicle screw system of  FIG. 33 . 
         FIG. 37  is a bottom view of the system engaging a pedicle screw system of  FIG. 33 . 
         FIG. 38  is a top perspective view of another embodiment of a system engaging a pedicle screw system. 
         FIG. 39  is a top perspective view of the system engaging a pedicle screw system of  FIG. 38  exploded away from each other. 
         FIG. 40  is a top view of the system engaging a pedicle screw system of  FIG. 38 . 
         FIG. 41  is a side view of the system engaging a pedicle screw system of  FIG. 38 . 
         FIG. 42  is a bottom view of the system engaging a pedicle screw system of  FIG. 38 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a first embodiment of the implantable connector system  20  and/or rotational connector  30 . In the embodiments described herein, the context of a revision surgery will be used as an example, it being understood that the principles, methods, and structures involved are equally suited in the context of primary surgery as well. For example, in the context of a revision surgery, the embodiments describe the rod that is connected to the “primary fusion rod” to be a “revision rod”. However, in primary fusion surgeries using the apparatus herein, the “revision rod” is more generically referred to as a secondary fusion rod. 
     In a first embodiment as shown in  FIGS. 1-10 , the apparatus includes a top-loading, rotatable, in-line rotational connector  30  for coupling a revision rod  40 , or secondary rod, to a primary (pre-existing, if in a revision surgery) fusion rod  2  of a pedicle screw system  1 . The rotational connector  30  is a top loaded “twist connect” design that fits over an existing pedicle screw  3 , or more specifically in some embodiments the screw head, and then twists into an in-line position ( FIG. 3 ) with a first end  30   a  of the rotational connector  30  cradling an end  2   a  of an existing primary fusion rod  2 . The rotational connector  30  is then secured to the end  2   a  of the primary fusion rod  2  with one or more set screws  50 . A first end  40   a  of a revision rod  40  is then inserted into the second end  30   b  of the rotational connector  30 , and secured with one or more set screws  60 . 
     As shown in the embodiment of  FIGS. 1-10 , the rotational connector  30  may include a receiving slot  31  to engage the pedicle screw  3  and the primary fusion rod  2 . In the embodiment shown, the receiving slot  31  may include a first slot  32  intersecting a second slot  33  to receive the pedicle screw  3  and the primary fusion rod  2 . The first slot  32  may extend upwardly from a bottom  34  of the rotational connector  30  for a first distance allowing the screw head  4  and primary fusion rod  2 , on one or both sides of the screw head, to be received within the first slot  32  of the rotational connector  30  when in the first orientation ( FIG. 2 ). The screw head  4  and/or primary fusion rod  2  may be substantially vertically inserted into the first slot  32  for the first distance. As such the rotational connector  30  may be vertically coupled to the screw head  4  and/or the primary fusion rod  2  when in the first orientation ( FIG. 2 ). The first slot  32  may be described in some embodiments as being in a substantially vertical first plane P 1 . The second slot  33  is transverse to and intersects the first slot  32  (i.e. perpendicular to the first slot). The second slot  33  may be described as being in a second plane P 2  transverse to the first plane. The second slot  33  may extend within the second plane P 2  from the first plane P 1  or first slot  32  passing through the central axis C of the rotational connector  30 , (i.e. the central axis of the screw head  4 ), and may extend in opposite rotational angles A from the first plane P 1  about the central axis C. The second slot  33  and/or first slot  32  do not have to be symmetric and/or similar in shape or size (length, width, and/or height) about the central axis C in some embodiments. For example although the second slot  33  is shown as extending through both rotational connector ends from the central axis C and/or portions of the first slot  32 , it should be understood that that second slot may not extend into the second end  30   b  in some embodiments such as when the primary fusion rod is not present or of a reduced distance/length on one side of the screw head  4  adjacent the revision rod  40 . The second slot  33  may be generally described as increasing in width along the second plane P 2  in opposing directions from the central axis C, or towards the first end  30   a  and opposing second end  30   b  of the rotational connector  30 . The second slot  33  may extend through opposing lateral sides  35 ,  36  of the rotational connector  30 , thereby creating open faces at the respective first end  30   a  and second end  30   b  of the rotational connector  30 . When the rotational connector  30  has been vertical positioned (i.e. downwardly) for a the first distance within the first slot  32  in the first orientation ( FIG. 2 ), these open faces or openings adjacent one or more of the connector ends allow the primary fusion rod  2  projecting from the screw head  4  in at least one direction to pass through and continue into the remaining portion of the second slot  33 . As such, at least the primary fusion rod  2  travels or rotates within the second slot  33  for a second distance or angle on one or both sides of the screw head  4  and/or middle portion  30   c . Thereby when positioning the rotational connector  30  from the first orientation ( FIG. 2 ) to the second orientation ( FIGS. 1 and 3-5 ), the rotational connector  30  further rotates for an angle A relative to the primary fusion rod  2  and the screw head  4  traveling within the second slot  33 . It should be understood that one or more slots may be used to vertically insert and/or rotate the rotational connector  30  relative to the pedicle screw  3  and/or primary fusion rod  2 . For example, a helical slot extending upwardly from the bottom  34  of the rotational connector may provide for the vertical and rotational movement of the rotational connector relative to the pedicle screw and rod. 
     The rotational connector  30  may include a variety of structure to define the receiving slot  31  that allows axial and rotational engagement with the pedicle screw system  1  between the first orientation and second orientation (i.e. screw head  4  and primary fusion rod  2 ). In the embodiment shown in  FIGS. 1-10 , the rotational connector  30  may include a first end  30   a , second end  30   b , and a middle portion  30   c  between the first end  30   a  and second end  30   b  in some embodiments. The middle portion  30   c  may include a cylindrical wall defining a through opening  37  to receive or slip over a top portion of the screw head  4 . The through opening  37  may be a portion of the first slot  32  and/or second slot  33 . The first end  30   a  and second end  30   b  project in opposing directions from the outer periphery of the wall of the middle portion  30   c . The first end  30   a  of the rotational connector  30  receives an outer surface of the primary fusion rod  2 . The first end  30   a  may be generally described as U-shaped or a C-channel extending from the middle portion  30   c . The first end  30   a  of the rotational connector includes a top member  38   a  and bottom member  38   b  connected by a side member  38   c . The top and bottom members  38   a ,  38   b  are separated by the second slot  33  and define the open face of the first end  30   a  within the lateral side  36 . In some embodiments, the bottom member  38   b  may include a tapered edge  38   d  defining the first slot  32  for substantial vertical insertion from the bottom  34 . The open face extends from the lateral side  36  to a distal free end  38   e . The side member  38   c , opposite the open face, may be an abutment to the primary fusion rod  2  in its neutral position in the second orientation ( FIG. 3 ) of the rotational connector  30 . The first end  30   a  of the rotational connector  30  may include one or more set screw openings  50   a ,  50   b . In the embodiment shown, the top member  38   a  of the first end  30   a  includes one or more set screw openings  50   a  and  50   b  to receive one or more connector set screws  50 . The connector set screws  50  may compress the primary fusion rod  2  against the bottom member  38   b  to secure the rotational connector  30  in the second orientation. The second end  30   b  of the rotational connecter  30  may couple adjacent ends of the primary fusion rod  2  and the revision rod  40 . The second end  30   b  of the rotational connector  30  may include a receptacle  70  configured to receive a first end  40   a  of the revision rod  40 . On embodiment of the receptacle  70  of the second end  30   b  opposite the first end  30   a  may include a top member  71  and a depending side member  72 . The top member  71  and/or side member  72  may define a portion of the second slot  33  and the open face in the opposite facing direction or lateral side  35  of the first ends&#39; open face on the lateral side  36 . The open face extends from the lateral side  35  to the distal free end  73  in some embodiments. The open faces of the first and second ends  30   a  and  30   b  face in the same rotational direction (i.e. clockwise direction), towards the second orientation. The side member  72  of the second end  30   b  may be a rotational stop of the primary fusion rod  2 , if the side member and/or primary fusion rod end is present. In some embodiments, side members  72  may not be used or saddle the primary fusion rod. Further in some embodiments, the middle portion  30   c  and the first end  30   a  may define the receiving slot  31  to receive the screw head  4  and primary fusion rod  2  therein (see  FIGS. 26-42 ). Although not shown, a bottom member may be used in the second end  30   b  if desired. In some embodiments, the second end  30   b  may not include a portion of the second slot  33  and/or receiving slot  31 . The one or more lateral sides  35  and  36  of the second end  30   b  or receptacle  70  may include a protrusion  74 , or alternatively a recess in some embodiments, to interlock with a revision rod  40  in some embodiments. The interlocking of the second end  30   b  or receptacle  70  (i.e. outer periphery and/or inner periphery) and the revision rod  40  may reduce separation. In the embodiment shown, the protrusion  74  is a vertical rib projecting from each lateral side  35 ,  36  of the second end  30   b . As such the revision rod engagement would have a corresponding engagement feature. The revision rod  40  in the embodiment shown in  FIGS. 1, 4, 5, and 9  may include a vertical recess or channel  41  to slidingly receive the vertical rib or protrusion  74  of the rotational connector  30 . The second end  30   b  of the rotational connector  30  may include one or more set screw openings  60   a  to receive a revision rod set screw  60  to couple the revision rod  40  to the rotational connector  30 . The first end  40   a  of the revision rod includes an opening  42  receiving the revision rod set screw  60 . In the embodiment shown, the top member  71  of the second end  30   b  includes the set screw opening  60   a.    
     As shown in  FIGS. 1, 4, 5, and 9 , the revision rod  40  may couple to the second end  30   b  of the rotational connector  30 . As shown in the embodiment of  FIG. 1 , the first end  40   a  of the revision rod  40  couples to the second end  30   b  or receptacle  70  of the rotational connector  30 . The first end  40   a  of the revision rod  40  includes an inner periphery  43  sliding over the outer periphery of the second end  30   b  of the rotational connector  30 . The revision rod set screw  60  threadingly engages the revision rod  40  to the second end  30   b  of the rotational connector  30 . When the rotational connector  30  is in the second orientation, the revision rod  40  is substantially aligned. In the embodiment shown in  FIG. 5 , the revision rod  40  may be substantially co-axial (i.e. substantially vertically and horizontally aligned with the primary fusion rod  2 ). It should be understood that a variety of embodiments of the rotational connector  30 , receptacle  70 , and/or revision rod  40  may be used to orientate and/or position the revision rod in a variety of angles and/or heights relative to the rotational connector  30  for a particular application. It should also be understood that the receptacle  70  engaging the revision rod  40  may be of a variety of shapes, sizes, quantities, and constructions and still position the revision rod for an application. 
     The rotational connector  30  may be described as having a “twist connect” design. The rotational connector  30 , or more specifically the middle portion  30   c , is adapted to fit a variety of screw sizes. The through openings  37  may be sized in diameter and/or height to correspondence to a variety of screw head  4  or pedicle screw  3  designs. The height of the rotational connector  30  may not extend vertically above the existing screw head in some embodiments. Moreover, the revision rod may not extend above the vertical extent of the rotational connector, or portions thereof. In the embodiment shown in  FIGS. 2-5 , the first end  40   a  of the revision rod  40  is received in a recessed or lower surface  75  of the second end  30   b  creating a substantially planar top surface of the combined revision rod  40  and rotational connector  30 . The recessed surface  75  may include the top member  71  at a lower elevation than the top surface of the middle portion  30   c . When combined as shown in  FIG. 5 , the revision rod  40  is substantially in line with the existing primary fusion rod  2 . The rotational connector  30  may allow the revision rod  40  to be inserted sub muscularly in some embodiments. The rotational connector is top loaded onto the pedicle screw (i.e. vertical movement) (see  FIGS. 2 and 3 ). The rotational connector  30  may be rotated from a first orientation ( FIG. 2 ) wherein the screw head is engaged at a vertical or down position and the primary fusion rod  2  is disengaged to a second orientation ( FIG. 3 ) wherein the screw head  4  and one or more of the opposing ends of the primary fusion rod  2  extending away from the screw head is engaged. The rotational connector  30  may be placed by rotating an acute angle between the first orientation to the second orientation. In some embodiments, the angle may be a variety of angles between the orientations (i.e. obtuse angle). In the embodiment shown, the rotational connector  30  travels about 30 degrees between the first orientation and the second orientation. When the rotational connector is rotated to the second orientation, or neutral position, one or more set screws  50  may lock the rotational connector  30  to the primary fusion rod  2 . The revision rod  40  may be top loaded upon rotational connector  30  and axially aligned with the primary fusion rod  2  and secured to the rotational connector  30  by one or more screws  60 . The revision rod  40  may not be axially aligned in some embodiments. 
     The end of the existing fusion rod can protrude beyond the pedicle screw in a range of distances, which are typically not known ahead of time since it was a result of the previous surgeon&#39;s work. The rotational connector herein is designed to be placed in-line over the existing rod with enough room to accommodate for nearly any amount of protrusion by the existing rod. Typically surgeons like to leave at least some amount of rod protruding beyond the screw to ensure that there is a guarantee that the rod is completely in the saddle of the screw for grip strength. The rotational connector herein is designed so that surgeons never need to adjust the pre-existing rod or construct because the goal is to leave the original fusion rod/construct untouched if possible, to minimize the risk of compromising fusion, as well as to eliminate the need to simply replace the existing fusion rod construct and the screws at the existing level when proceeding to build up to the next levels during revision surgery. 
     The revision rod can be as long as desired. Theoretically, the surgeon could run the revision rod all the way up the spine if desired, though this would not be typical. Usually, surgeons will elect to cut the revision rod to the desired length during revision surgery; thus, the revision rod herein can begin as long as desired, and then can be cut by the surgeon. 
     The set screws are prevented from backing out via their standard, well-known set screw thread design. This is the same mechanical principle that applies to a pedicle screw with a locking set screw: once a recommended torque on the set screws is achieved, the set screws are secure. 
     In this first embodiment shown in  FIGS. 2-4, 6, and 7 , one or more ridges, tongues, or protrusions  74  are provided on the external surface of the second end  30   b  of the rotational connector  30 . These protrusions  74  mate with corresponding grooves inside the first end  40   a  of the revision rod head portion. These protrusions  74  are designed to interface to carry the load between the two components. This way the set screw  60  does not have to sustain the full load in some embodiments. In other embodiments they could be replaced by a single spherical surface (as, e.g., in a second embodiment described below) or by a rod that has a female spherical ball end that drops into a mating spherical cavity of the rotational connector shown and described in an embodiment below. The purpose of these alternatives is to prevent separation and allows the rod to be angulated in order to accommodate less than perfectly placed pedicle screws. This allows for a more secure connection while allowing for some variation in placement. 
     The rotational connector  30  that accepts the existing rod is designed to have a geometric shape that adds structural stability to the rotational connector as shown in  FIG. 3 . The material of the rotational connector  30  creates a tall wall or side member  38   c  on one side of the existing rotational connector  30 . The rotational connector can accept most commonly used rods (such as, e.g., 5.5 mm rods), but obviously can be easily dimensioned to fit on larger or small diameter rods as desired. The rotational connector itself has an inner diameter and surface that defines the through opening  37  and accommodates the many sizes of pedicle screws used by many manufacturers throughout the years. 
     The rotational connector  30  can be inserted into a patient in a standard open procedure, or can be inserted sub-muscularly or percutaneously. In this fashion, the rotational connector  30  can be categorized as an MIS connector. 
     As shown in  FIG. 2 , in one embodiment for one example application (spinal fusion revision surgery), the rotational connector  30  fits around the head of an existing, previously implanted screw, and then rotates into an in-line position with an existing, previously implanted fusion rod. The rotational connector  30 , at the angle of the first orientation, slides over the screw head  4  vertically to a position or down position within the first slot  32  of the receiving slot  31  and subsequently rotates within the second slot  33  of the receiving slot  31  to the second angle of the second orientation. 
     Several options are used to accommodate pedicle screws  3  from various manufacturers, including multiple sizes of through openings  37  in the rotational connector in order to ensure a tight fit therearound. 
     In a second embodiment show in  FIGS. 11-17 , the implantable connector system  120  may provide adjustability for the relative angle of the revision rod  140  relative to the rotational connector  130 . Another embodiment of the second end  130   b  of the rotational connector is shown in  FIGS. 11 and 14 . The rotational connector  130  includes external serrations or teeth  174  on the outer surface of the revision rod receiving end or receptacle  170 . The second end  130   b  includes external vertical serrations  174  on the outer periphery (i.e. the lateral sides and interconnecting distal free end). The outer periphery of the second end  130   b  may by arcuate in shape. The first end  140   a  of the revision rod may have a corresponding shape to engage the second end  130   b . The inner periphery of the first end  140   a  of the revision rod  140  includes serrations  141  at least in the upper portion of the cavity. The corresponding serrations  141  and  174  between the structures may interlock or interfere with relative rotation therebetween. In the embodiment shown in  FIG. 12 , when the revision rod  140  is positioned at the desired angle B relative to the second end  130   b  of the rotational connector  130 , the revision rod is vertically coupled. The revision rod set screw  60  as shown in  FIG. 17  is then threadingly engaged. The revision rod  140  may be in substantially the same horizontal plane of the primary fusion rod  2  and still be a variety of angular positions (i.e. angle B) relative to the second end  130   b  of the rotational connector  130 . Moreover, the rotational connector  130  includes another embodiment of the first end  130   a . The first end  130   a  of the rotational connector  130  includes a single set screw opening  150   a  for threadingly engaging a corresponding connector set screw  150 . 
     Any number and type, size, and design of serrations  174  are possible. These serrations  174  allow a surgeon to place the revision rod  140  at an angle B with respect to the pre-existing fusion rod  2 . While the figures shows an example angle B of ten degrees per side, this is just an example, and any number of angles are possible from zero to approximately 90 degrees per side, depending on the fit between the revision rod  140  and the rotational connector  130 , and where the construct is to be implanted in the patient. The rounded second end  130   b  of the rotational connector  130  may allow for medial/lateral revision rod  140  rotation. 
     In this embodiment, as in all the embodiments, any number of set screws or screws can be utilized, depending on the size and shape of the construct required. Often, surgeons desire the smallest profile possible from an implant that does not compromise strength. In some embodiments as shown in  FIGS. 12 and 15 , a single larger set screw  150  will have a smaller profile than two set screws  50  of  FIG. 3 , for example. 
     In a third embodiment of the implantable connector system  220  shown in  FIGS. 18-24 , another engagement between a revision rod  240  and rotational connector  230  may be used in a variety of applications. The rotational connector second end  230   b  or receptacle  270  that receives the first end  240   a  of the revision rod  240  is fitted with a socket  276  to receive a “ball” end  244  of the revision rod  240 , as shown in  FIGS. 19 and 21 . As shown in this embodiment, the second end  230   b  or receptacle  270  of the rotational connector  230  may positon the first end  240   a  of the revision rod  240  in a different vertical position or another horizontal plane relative to the primary fusion rod  2 . However, the adjacent ends of the rods  240  and  2  may be substantially in the same horizontal plane, or along the longitudinal axis, of the rotational connector  230  in some embodiments (See  FIG. 25 ). The top surface of the second end  230   b  of the rotational connector  230  may be at a higher elevation or horizontal plane relative to the remaining portions of the rotational connector (i.e. middle portion  230   c  and/or first end  230   a ). For example, the top surface of the second end  230   b  may be 0.2 inches or 5 mm above top surface of the middle portion  230   c  of the rotational connector in some embodiments. 
     In the embodiment shown in  FIGS. 18-24 , angulation of the revision rod  240  can be achieved via the ball-and-socket joint,  276  and  244 . Once the desired angle is achieved by the surgeon, a revision rod set screw  260  is tightened against to hold the angle. This is akin to the polyaxial nature of many pedicle screws; here the set screw contacts the spherical head of the revision rod directly. There may be increased strength (i.e. torsion, F/E, compression) between the revision rod interface. Moreover, the spherical angulation between the revision rod  240  and the rotational connector  230  may increase variability and ease of insertion with adjacent levels. 
     Other options exist for achieving, and then holding, the desired angulation, including the use of compression collets around the spherical head of the revision rod, as described in commonly owned U.S. Pat. No. 8,197,517, the disclosure of which is incorporated by reference herein. Such a friction collet provides a means to grip and secure the rod at the desired position once placed and the set screw is tightened to the recommended tightening torque. Another option is the use of a set screw that is integrally formed within a body that has a saddle-shaped blocking mechanism. The saddle has a post at its central axis around which the set screw rotates. The saddle block could be designed to lock certain angulations. For example, one saddle might be a zero angle saddle, wherein each side of the saddle is of equal size and shape, and it fits down over the revision rod. A different saddle might have one “leg” larger or thicker than the other, which would lock in a particular angle. Another option is having the bottom of the locking set screw for the rod have a spherical underbody with spherical shaped ridges to increase grip strength to secure the rod in position once placed. This locking set screw has a spherical cavity much like the concept of the collet. 
     Another embodiment of the rotational connector  330  is shown in  FIG. 25 . The rotational connector  330  may include an embodiment of a second end  330   b  that positions the first end  240   a  of the revision rod substantially in the same horizontal plane, along the longitudinal axis, of the rotational connector or primary revision rod  2 . The revision rod may be axially aligned with the second slot or primary fusion rod in some embodiments. The receptacle  370  or ball-and-socket joint (i.e. socket  376 ) may be adjacent the end of the primary fusion rod or lower in elevation than the ball-and-socket joint in  FIG. 20 . Another embodiment of the second end  330   b  as shown in  FIG. 25  includes a distal free end  373  that may cover at least a portion of the axial end of the primary fusion rod  2 . As such the second slot  333  may not extend through the distal free end  373  of the second end  330   b  in some embodiments. The inside surface of the distal free end  373  may abut against the axial end of the primary fusion rod  2  or be spaced from the inside surface of the distal free end  373 . 
     Another embodiment of the implantable connector system  420  is shown in  FIGS. 26-33 . The rotational connector  430  includes a receiving slot  431  not extending through the second end  430   b . The first and second slots  432  and  433  extend upwardly into the middle portion  430   c  and the first end  430   a . The through opening  437  may be enclosed by the wall of the middle portion  430   c . Therefore the end of the primary fusion rod  2  may not extend radial past the through opening  437  from the screw head  4  to allow the rotation of the rotational connector  430  from the first orientation ( FIG. 30 ) to the second orientation ( FIGS. 31-33 ). Moreover in the embodiment shown in  FIG. 26 , the top surface of the second end  430   b  is substantially planar with the top surface of the middle portion  430   c . As best shown in  FIGS. 26 and 27 , the second end  430   b  positions the revision rod  40  in a spaced elevation, or different horizontal plane, from the axis of the primary fusion rod  2 . However it should be understood that a recessed surface  75  may be used with this embodiment. If a recess is used in an embodiment the revision rod  40  may be horizontally and vertically aligned with the primary fusion rod  2 . 
     Another embodiment of the implantable connector system  520  is shown in  FIGS. 34-37 . Generally similar to the embodiment of the implantable connector system  120 , however the rotational connector  530  includes a receiving slot  531  not extending through the second end  530   b . The first and second slots  532  and  533  extend upwardly into the middle portion  530   c  and the first end  530   a . The through opening  537  may be enclosed by the wall of the middle portion  530   c . The second end  530   b  does not include a sidewall depending from the top member  571  with serrations  574 . Moreover in this embodiment, the second end  530   b  does not include a recessed surface  75  as in  FIG. 3 . However, a recess may be used. As shown in  FIGS. 33 and 35 , the revision rod  140  is positioned at an angle B, being zero degrees in the application shown. 
     Another embodiment of the implantable connector system  620  is shown in  FIGS. 38-42 . The rotational connector  630  includes a receptacle  670  positioning the revision rod  240  substantially in line with the primary fusion rod  2 . The receptacle  670  of the second end  630   b  includes a ball-and-socket joint as described above. The receptacle  670  is substantially in line with the primary fusing rod  2 , similar to the embodiment in  FIG. 25 . Further, the first end  630   a  of the rotational connector  630  illustrates a single set screw  50  being used. Although two or more set screws are contemplated. The set screw  50  and/or opening  50   a  is offset within the top member  638   a  from the axis of the primary fusion rod  2  or spaced from the side member  638   c . Moreover, the set screw  50  is not positioned over the bottom member  638   b . Stated alternatively, the first and second slots  632  and  633  of the receiving slot  631  are defined by a variety of surfaces and/or structure. For example, when the rotational connector  630  is top loaded upon the screw head  4 , the bottom  634  of the middle portion  630   c  does not substantially extend downwardly past the upper extent of the primary fusion rod  2 . 
     While several embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, embodiments may be practiced otherwise than as specifically described and claimed. Embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law. 
     As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc. 
     It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited. 
     In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03. 
     The foregoing description of several embodiments of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention and all equivalents be defined by the claims appended to the application once filed as a non-provisional application.