Abstract:
Embodiments of the present invention are directed toward a system of apparatuses to correct spinal deformities along with associated surgical techniques. The apparatuses comprise passages or channels in which spinal rods of differing diameters may be secured to allow a surgeon to vary the diameter of rods used along the length of the spine. Additionally, embodiments of the present invention are directed toward instrumentation for reduction of spinal rods into spinal pedicle screws.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/646,030 filed May 11, 2012 and U.S. Provisional Application Ser. No. 61/798,414 filed Mar. 15, 2013, which are incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a system and technique for spinal surgery. Spinal implants, including connectors, hooks, screws and rods, are used to correct spinal deformities. Screws and connectors in combination with spinal rods can align and correct deformities in the natural spinal alignment as well as repair traumatic injury. Additionally, instrumentation for reduction of spinal rods into spinal pedicle screws is provided in the present disclosure. 
     BACKGROUND 
     Spinal fixation systems may be used in surgery to fix, adjust, and/or align the spinal column. One type of spinal fixation system employs a spinal rod for supporting the spine and fixing, adjusting, and/or aligning the spinal column into the desired orientation. Attachment of the spinal rod to the spinal column has been achieved using a variety of vertebral anchors. Vertebral anchors include screws, hooks, pins, and bolts used to engage the vertebrae and connect the spinal rod to different vertebrae. 
     The length and diameter of the spinal rod depends on the size and number of vertebrae to be held in a desired position by the spinal fixation system. The size of the spinal rod also depends on the region of the spine where the spinal fixation system is used. For example, in the cervical region of the spine, where the vertebrae tend to be smaller, a relatively smaller spinal rod is used. Conversely, in the thoracic region, where heavier loads are experienced and the vertebrae tend to be larger, a spinal rod having a relatively larger diameter is used. The cervico-thoracic junction of the spine is typically instrumented using spinal rods of two different diameters to accommodate anatomical differences between the cervical and thoracic spine regions. To accommodate a spinal fixation system including spinal rods having different sizes and configurations, a rod connector may be used to join a first spinal rod and a second spinal rod together. The rod connector may be a side-by-side connector, where the ends of the two spinal rods are placed side-by-side and connected using a connector that spans the two ends, or an axial connector, which aligns the axes of the two spinal rods and connects the ends of the spinal rods together along the axial direction. The plurality of possible spinal rod diameters in combination with the plurality of connector arrangements results in a surgeon typically requiring a vast array of connectors on hand in preparation for a given spinal surgery. 
     The spinal rods in a spinal fixation system may necessarily be bent to conform to a desired curvature of the spinal column in one or more of the anatomic planes as part of a spinal fixation or corrective surgery. Attachment of spinal rods to vertebral anchors such as screws, hooks, pins, and bolts may be complicated by differing curvature of the untreated spine and the curvature of the spinal rod. Instrumentation to force the spinal rod into engagement with the vertebral anchors may be used. Challenges arise in utilizing instrumentation to force the spinal rod into engagement with the vertebral anchors because the instrumentation generally must be releasably affixed to a previously implanted vertebral anchor and the locking mechanism on the vertebral anchor must be engaged while maintaining the spinal rod in the correct position. Simple engagement of the instrumentation with the vertebral anchor is desirable. 
     SUMMARY 
     In one embodiment, a medical device having a spinal rod receiving channel and a rod retaining set screw is provided. The spinal rod receiving channel has at least a first circular hole, a second circular hole, and a third circular hole overlapping in parallel arrangement. The first circular hole, the second circular hole, and the third circular hole have offset centers disposed along a single line. The first circular hole forms an upper arc of the rod receiving channel; the second circular hole forms a middle arc of the rod receiving channel; the third circular hole forms a lower arc of the rod receiving channel; and the middle arc and the lower arc are connected by a connecting slant. The rod retaining set screw secures a spinal rod disposed in the spinal rod receiving channel into the medical device. 
     In another embodiment, a medical device having a plurality of spinal rod receiving channel and a plurality of retaining set screw is provided. The spinal rod receiving channels each have at least a first circular hole, a second circular hole, and a third circular hole overlapping in parallel arrangement. The first circular hole, the second circular hole, and the third circular hole have offset centers disposed along a single line. The first circular hole forms an upper arc of the rod receiving channel; the second circular hole forms a middle arc of the rod receiving channel; the third circular hole forms a lower arc of the rod receiving channel; and the middle arc and the lower arc are connected by a connecting slant. The rod retaining set screws secures a spinal rod disposed in each of the spinal rod receiving channels into the medical device. 
     In another embodiment, a medical device having a spinal rod receiving channel, a rod retaining set screw, and a hook for engagement with the lamina of a vertebrae is provided. The spinal rod receiving channel has at least a first circular hole, a second circular hole, and a third circular hole overlapping in parallel arrangement. The first circular hole, the second circular hole, and the third circular hole have offset centers disposed along a single line. The first circular hole forms an upper arc of the rod receiving channel; the second circular hole forms a middle arc of the rod receiving channel; the third circular hole forms a lower arc of the rod receiving channel; and the middle arc and the lower arc are connected by a connecting slant. The rod retaining set screw secures a spinal rod disposed in the spinal rod receiving channel into the medical device. 
     In another embodiment, a medical device having a spinal rod receiving channel, a rod retaining set screw, and a lateral connector rod with a diameter of approximately 4.75 mm or 5.5 mm for engagement with a spinal pedicle screw is provided. The spinal rod receiving channel has at least a first circular hole, a second circular hole, and a third circular hole overlapping in parallel arrangement. The first circular hole, the second circular hole, and the third circular hole have offset centers disposed along a single line. The first circular hole forms an upper arc of the rod receiving channel; the second circular hole forms a middle arc of the rod receiving channel; the third circular hole forms a lower arc of the rod receiving channel; and the middle arc and the lower arc are connected by a connecting slant. The rod retaining set screw secures a spinal rod disposed in the spinal rod receiving channel into the medical device. 
     A another embodiment, a medical device having a first cross connector rod hook and a second cross connector hook for securing spinal rods, two conical screw receiving ports, and two rod retaining conical screws is provided. The first and second cross connector rod hooks have at least a first circular bore, a second circular bore, and a third circular bore which in combination form a hook with an open portion. The first circular bore, the second circular bore, and the third circular bore are parallel and have offset centers disposed along a single line. The first circular bore forms an upper arc of the cross connector rod hook; the second circular bore forms a middle arc of the cross connector rod hook; the third circular hole forms a lower arc of the cross connector rod hook; and the middle arc and the lower arc are connected by a connecting slant. The rod retaining conical screws secure a spinal rod disposed in the first and second cross connector rod hooks into the medical device. 
     In another embodiment, a medical device having a first cross connector rod hook and a second cross connector hook for securing spinal rods, two conical screw receiving ports, and two rod retaining conical screws is provided. The first and second cross connector rod hooks have at least a first circular bore, a second circular bore, and a third circular bore which in combination form a hook with an open portion. The first circular bore, the second circular bore, and the third circular bore are parallel and have offset centers disposed along a single line. The first circular bore forms an upper arc of the cross connector rod hook; the second circular bore forms a middle arc of the cross connector rod hook; the third circular hole forms a lower arc of the cross connector rod hook; and the middle arc and the lower arc are connected by a connecting slant. The rod retaining conical screws secure a spinal rod disposed in the first and second cross connector rod hooks into the medical device. The medical device further has a first linkage, a second linkage, a pivot post, and a midline nut. The first linkage comprises the first cross connector hook, one of the conical screw receiving ports and a bi-axial cross connector extension rod. The second linkage comprises the second cross connector hook, one of the conical screw receiving ports and a bi-axial cross connector. When assembled the bi-axial cross connector extension rod is disposed in the bi-axial cross connector extension rod channel, the linkage retaining orifice is disposed over the threaded post, and the midline nut is disposed on the threaded post. 
     In another embodiment, a medical instrument having a rod reduction assembly and a pedicle screw engaging assembly is provided. The rod reduction assembly comprises a rod reduction sleeve, a reduction rod, and an advancing knob. The reduction sleeve comprises a hollow, cylindrical shaped body having an internal reduction sleeve channel, reduction rod engagement slots on a first end, and rod engagement radii on a second end. The reduction rod comprises external reduction rod threads on a first end and the advancing knob comprises internal threads matched to the external reduction rod threads. The reduction rod has first and second extenders extending radial from the outer surface proximal a second end which engage with the reduction rod engagement slots. The pedicle screw engaging assembly has fingers for engagement with the head of a pedicle screw, finger cam pins, an inner tube, and a release ring. The fingers each comprise a finger hook having a finger hook undercut, a finger slot, and a finger aperture. The finger slot have a first end distal the finger hook with a width sufficient to permit finger cam pin to slide through but not enough for substantial lateral movement transverse to the sliding direction and a second end proximal the finger hook with a larger width to form a clearance fit with the finger cam pin. The inner tube comprises a hollow, cylindrical body having a first inner tube end and a second inner tube end, a first inner tube slot and a second inner tube slot diametrically opposed across the cylindrical body, and a first finger slot and a second finger slot diametrically opposed across the cylindrical body. The first inner tube slot and the second inner tube slot are open toward the second inner tube end and the fingers are disposed in the first finger slot and the second finger slot with the fingers oriented to dispose the finger hooks proximal the second inner tube end and the finger hook undercuts toward the interior of the inner tube. Movement of the release ring from a first position to a second position moves the finger cam pins from the second end of the finger slot to the first end of the finger slot thereby positioning the fingers for insertion of the head of a pedicle screw. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: 
         FIG. 1  is an isometric view of an embodiment of a dual diameter connector with rods disposed therein; 
         FIG. 2A  is a top view of an embodiment of a dual diameter connector; 
         FIG. 2B  is an end view of an embodiment of a dual diameter connector; 
         FIG. 2C  is a front section view of an embodiment of a dual diameter connector; 
         FIG. 3A  is a top view of an embodiment of a dual diameter connector; 
         FIG. 3B  is an end view of an embodiment of a dual diameter connector; 
         FIG. 4  is a top view of an embodiment of a dual diameter connector; 
         FIG. 5A  is a front profile view of an embodiment of a dual diameter closed laminar hook; 
         FIG. 5B  is a side view of an embodiment of a dual diameter closed laminar hook; 
         FIG. 6  is an isometric view of an embodiment of a dual diameter open laminar hook; 
         FIG. 7A  is a top view of an embodiment of a dual diameter fixed cross connector; 
         FIG. 7B  is a front view of an embodiment of a dual diameter fixed cross connector; 
         FIG. 8  is an isometric view of an embodiment of a dual diameter fixed cross connector; 
         FIG. 9A  is a top view of an embodiment of a dual diameter closed lateral connector; 
         FIG. 9B  is a front view of an embodiment of a dual diameter closed lateral connector; 
         FIG. 9C  is an isometric view of an embodiment of a dual diameter closed lateral connector; 
         FIG. 10A  is a front view of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 10B  is a top view of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 11A  is a front section view of an embodiment of a first linkage of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 11B  is a top view of an embodiment of a first linkage of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 12A  is a side view of an embodiment of a pivot post of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 12B  is a front view of an embodiment of a pivot post of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 13A  is a front section view of an embodiment of a second linkage of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 13B  is a top view of an embodiment of a second linkage of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 14A  is a front view of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 14B  is a front section view of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 14C  is a top view of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 15  is an isometric view of an embodiment of a midline locking post post of an embodiment of a dual diameter bi-axial cross connector; 
         FIG. 16A  is a profile view of an embodiment of a rod reduction device; 
         FIG. 16B  is a profile view of an embodiment of a rod reduction device; 
         FIG. 16C  is a section view of an embodiment of a rod reduction device; 
         FIG. 17A  is a profile view of an embodiment of a housing tube of a rod reduction device; 
         FIG. 17B  is a profile view of an embodiment of a housing tube of a rod reduction device; 
         FIG. 17C  is a section view of an embodiment of a housing tube of a rod reduction device; 
         FIG. 18A  is a front profile view of an embodiment of an advancing knob of a rod reduction device; 
         FIG. 18B  is a profile view of an embodiment of an advancing knob of a rod reduction device; 
         FIG. 19A  is a front profile view of an embodiment of a reduction rod of a rod reduction device; 
         FIG. 19B  is a section view of an embodiment of a reduction rod of a rod reduction device; 
         FIG. 20  is a section view of an embodiment of a cap of a rod reduction device; 
         FIG. 21A  is a front profile of an embodiment of a inner tube of a rod reduction device; 
         FIG. 21B  is a side profile of an embodiment of a inner tube of a rod reduction device; 
         FIG. 21C  is a front section view of an embodiment of a inner tube of a rod reduction device; 
         FIG. 21D  is a top section view of an embodiment of a inner tube of a rod reduction device; 
         FIG. 22A  is a front view of an embodiment of a retractor sleeve of a rod reduction device; 
         FIG. 22B  is a side view of an embodiment of a retractor sleeve of a rod reduction device; 
         FIG. 22C  is a front section view of an embodiment of a retractor sleeve of a rod reduction device; 
         FIG. 23  is an isometric view of an embodiment of a reduction sleeve of a rod reduction device; 
         FIG. 24A  is a front view of an embodiment of a release ring of a rod reduction device; 
         FIG. 24B  is a section view of an embodiment of a release ring of a rod reduction device; 
         FIG. 25A  is an isometric view of an embodiment of a finger of a rod reduction device; 
         FIG. 25B  is a section view of an embodiment of a finger of a rod reduction device; 
         FIG. 25C  is a top view of an embodiment of a finger of a rod reduction device; 
         FIG. 25D  is a section view of an embodiment of a finger of a rod reduction device; 
         FIG. 26A  is a front view of an embodiment of a weld sleeve of a rod reduction device; 
         FIG. 26B  is a side view of an embodiment of a weld sleeve of a rod reduction device; 
         FIG. 26C  is a section view of an embodiment of a weld sleeve of a rod reduction device; 
         FIG. 26D  is a top view of an embodiment of a weld sleeve of a rod reduction device; 
         FIG. 27  is an isometric view of an embodiment of a finger cover of a rod reduction device; 
         FIG. 28A  is a sub-assembly of an embodiment of a rod reduction device; 
         FIG. 28B  is a detail view of a sub-assembly of an embodiment of a rod reduction device; 
         FIG. 29A  is a sub-assembly of an embodiment of a rod reduction device; 
         FIG. 29B  is a sub-assembly of an embodiment of a rod reduction device; 
         FIG. 30A  is a sub-assembly of an embodiment of a rod reduction device; 
         FIG. 30B  is a sub-assembly of an embodiment of a rod reduction device; 
         FIG. 30C  is an exploded view of an embodiment of a rod reduction device; 
         FIG. 31  is a front profile view of an embodiment of a set screw driver; 
         FIG. 32A  is a side view of an embodiment of a rod reduction device attached to a spinal pedicle screw; 
         FIG. 32B  is a section view of an embodiment of a rod reduction device attached to a spinal pedicle screw; 
         FIG. 32C  is a detail section view of an embodiment of a rod reduction device attached to a spinal pedicle screw; 
         FIG. 33A  is a side view of an embodiment of a rod reduction device attached to a spinal pedicle screw with the reduction sleeve engaging a spinal rod; 
         FIG. 33B  is a section view of an embodiment of a rod reduction device attached to a spinal pedicle screw with the reduction sleeve engaging a spinal rod; 
         FIG. 33C  is a detail section view of an embodiment of a rod reduction device attached to a spinal pedicle screw with the reduction sleeve engaging a spinal rod; 
         FIG. 34A  is a side view of an embodiment of a rod reduction device attached to a spinal pedicle screw, a spinal rod reduced into the spinal pedicle screw, and a rod retaining set screw inserted; 
         FIG. 34B  is a section view of an embodiment of a rod reduction device attached to a spinal pedicle screw, a spinal rod reduced into the spinal pedicle screw, and a rod retaining set screw inserted; 
         FIG. 34C  is a detail section view of an embodiment of a rod reduction device attached to a spinal pedicle screw, a spinal rod reduced into the spinal pedicle screw, and a rod retaining set screw inserted; 
         FIG. 35A  is a front profile view of an embodiment of a rod reduction assembly; 
         FIG. 35B  is a section view of an embodiment of a rod reduction assembly; 
         FIG. 36A  is a section view of an embodiment of a provisional locking instrument; 
         FIG. 36B  is a profile view of an embodiment of a provisional locking instrument; 
         FIG. 37A  is a front profile view of an embodiment of a spinal pedicle screw inserter; 
         FIG. 37B  is a section view of an embodiment of a spinal pedicle screw inserter; 
         FIG. 37C  is a detail section view of an embodiment of a spinal pedicle screw inserter; 
         FIG. 38  is a front profile view of an embodiment of a spinal pedicle screw inserter; 
         FIG. 39  is a front profile view of an embodiment of a spinal pedicle screw; 
         FIG. 40A  is a side profile view of an embodiment of a spinal pedicle screw; 
         FIG. 40B  is a front profile view of an embodiment of a spinal pedicle screw; 
         FIG. 40C  is a top profile view of an embodiment of a spinal pedicle screw; and 
         FIG. 40D  is a section view of an embodiment of a spinal pedicle screw. 
     
    
    
     DETAILED DESCRIPTION 
     Referring initially to  FIG. 1 , an isometric view of a wedding band inline dual diameter connector  110  with spinal rods  112 ,  114  disposed therein. The wedding band inline dual diameter connector  110  illustrated in  FIG. 1  specifically has a 5.5 mm diameter spinal rod  112  and a 4.75 mm diameter spinal rod  114  disposed therein. 
     The wedding band inline dual diameter connector  110  connects two spinal rods  112 ,  114  in a substantially parallel orientation. The wedding band inline dual diameter connector  110  allows a surgeon performing a spinal surgery to utilize multiple spinal rods  112 ,  114  along the length of the spine in lieu of a single long rod. Use of multiple spinal rods  112 ,  114  allows for different diameter spinal rods to be used along the length of the spine based on changes in anatomy. Changing diameters of spinal rods  112 ,  114  also allows for the mechanical properties, such as stiffness, of the fixation or deformity correction to be varied along the length of the patient&#39;s spine. 
     In addition to different sized spinal rods, multiple spinal rods of the same diameter may be connected together. For example, two 5.5 mm diameter spinal rods  112  may be joined. Additionally, two 4.75 mm diameter spinal rods  114  may be joined. 
     Referring to  FIGS. 2A-2C , an embodiment of a wedding band inline dual diameter connector  110 , rod receiving channels  122  are shown. The specific and special geometry of the rod receiving channels  122  allows for both 5.5 mm diameter spinal rods  112  and 4.75 mm diameter spinal rods  114  to be secured in the rod receiving channels. The rod receiving channels  122  are substantially a composite of three circular through holes. The resulting rod receiving channel  122  is comprised of one upper arc  410 , two middle arcs  412 , two connecting slants  416 , and one lower arc  414 . The upper arc  410  preferably has an approximately 2.76 mm to approximately 3.02 mm radius. For example, a radius of 2.890 mm. The middle arc  412  preferably has an approximately 2.595 mm to approximately 2.855 mm radius. For example, a radius of 2.725 mm. The lower arc  414  preferably has an approximately 1.87 mm to approximately 2.13 mm radius. For example, a radius of 2.000 mm. The connecting slant  416  preferably has a length of approximately 0.638 mm to approximately 0.898 mm. For example, a length of 0.768 mm. The centers of the upper arc  410 , the middle arc  412 , and the lower arc  414  are co-linear. The center of the middle arc  412  is located between the center of the upper arc  410  and the lower arc  414 . The centers of the upper arc  410  and middle arc  412  are preferably separated by approximately 1.00 mm to approximately 1.07 mm. The centers of the lower arc  414  and middle arc  412  are preferably separated by approximately 1.02 mm to approximately 1.09 mm. The angle of the connecting slant  416  is preferably approximately 42° to approximately 44° from the line formed by the centers of the upper arc  410 , the middle arc  412 , and the lower arc  414 . 
     Set screw receiving ports  124  are positioned in alignment with the rod receiving channels  122 . The set screw receiving ports  124  are configured to engage with a set screw  120  through threaded engagement. Set screw receiving threads  150  are positioned on the interior surface of the set screw receiving ports  124  to engage with external threads on set screw  120 . Set screws  120  are threaded into the wedding band inline dual diameter connector  110  and abutted against the spinal rods  112 ,  114  to secure the spinal rods into the wedding band inline dual diameter connector. 
     In an embodiment of the wedding band inline dual diameter connector  110 , a rod receiving channel relief  126  is disposed opposite each set screw receiving port  124 . The rod receiving channel relief  126  in an embodiment is a circular through hole diametrically opposite the set screw receiving port  124 . 
     Referring again to  FIG. 1 , the spinal rods  112 ,  114  are illustrated as translucent to allow the interface between the wedding band inline dual diameter connector  110  and the spinal rods to be seen. The 5.5 mm diameter spinal rod  112  contacts the wedding band inline dual diameter connector  110  in a 5.5 mm contact area  116  demarcated as a shaded region. The 4.75 mm diameter spinal rod  114  contacts the wedding band inline dual diameter connector  110  in a 4.75 mm contact area  118  demarcated as a second shaded region. Both the 5.5 mm contact area  116  and the 4.75 mm contact area  118  are mirrored on the opposing surface of the respective spinal rod  112 ,  114  and connector interface (not shown). 
     In a specific embodiment the 5.5 mm contact area  116  is approximately 32.08 mm 2  and the 4.75 mm contact area  118  is approximately 7.44 mm 2 . These contact areas can vary according to the limits of the full range of disclosed embodiments of the rod receiving channels  122 . 
     Referring to  FIG. 3A  and  FIG. 3B , a top profile and end profile respectively of an inline dual diameter connector  160  is shown. The inline dual diameter connector  160  has the same closed rod receiving channel  122  profile as described for the wedding band inline dual diameter connector  110 . In the inline dual diameter connector  160 , a single closed rod receiving channel  122  passes along the entire longitudinal axis. This arrangement allows two spinal rods  112 ,  114  to be abutted end to end without any lateral shift required. 
     Referring to  FIG. 4 , a domino inline dual diameter connector  180  is shown in a top profile view. The domino inline dual diameter connector  180  also has a front profile matching that of the wedding band inline dual diameter connector  110  as shown in  FIG. 2A  and  FIG. 2C . The arrangement of the domino inline dual diameter connector  180  is that of two inline dual diameter connectors  160  disposed side by side. 
     It is envisioned that four spinal rods  112 ,  114  can be secured together, wherein each single spinal rod is secured by an individual set screw  120  disposed in each of the four set screw receiving ports  124 . It is also envisioned that two spinal rods  112 ,  114  can be secured in a parallel orientation with two set screws  120  securing each spinal rod. The domino inline dual diameter connector  180  may secure any combination of 4.75 mm diameter spinal rods  114  and 5.5 mm diameter spinal rods  112  at each of the set screw receiving ports  124 . Non-limiting examples include two 4.75 mm diameter spinal rods  114  secured with two set screws  120  securing each rod, a single 4.75 mm diameter spinal rod  114  and a single 5.5 mm diameter spinal rod  112  with two set screws  120  securing each rod, two 4.75 mm diameter spinal rods  114  and two 5.5 mm diameter spinal rods  112  secured with one set screw  120  securing each rod, two 4.75 mm diameter spinal rods  114  and one 5.5 mm diameter spinal rod  112  secured with one set screw  120  securing each 4.75 mm diameter spinal rod and two set screws  120  securing the 5.5 mm diameter spinal rod, and two 5.5 mm diameter spinal rods  112  and one 4.75 mm diameter spinal rod  114  secured with one set screw  120  securing each 5.5 mm diameter spinal rod and two set screws  120  securing the 4.75 mm diameter spinal rod. 
     Referring to  FIG. 5A  and  FIG. 5B , a front profile view and a side profile view respectively of a closed laminar hook  210 . The closed laminar hook  210  comprises a set screw receiving port  124 , a closed rod receiving channel  122 , and a hook blade  212 . The hook blade  212  may be of varying widths and lengths. 
     Other standard styles and sizes of hooks are envisioned. Non-limiting examples include closed and open pedicle hooks, closed laminar hooks  210 , open laminar hooks  220 , open thoracic hooks, open offset thoracic hooks, and open offset lumbar hooks. 
     Referring to  FIG. 6 , an isometric view of an open laminar hook  220 . The open laminar hook  220  comprises an open rod receiving saddle  222  and a hook blade  212 . The hook blade  212  may be of varying widths and lengths. 
     The open rod receiving saddle  222  comprises the same geometry as closed rod receiving channel  122  except the upper arc  410  is not present and a portion of middle arc  412  may also be not present. In an embodiment, the upper threaded portion of the open laminar hook  220  may replicate the geometry of any uniaxial or polyaxial spinal screw known to one skilled in the art. Additionally, in an embodiment of the open laminar hook  220  the external geometry may replicate the external shape and geometry of any uniaxial or polyaxial spinal screw known to one skilled in the art. 
     Referring to  FIG. 7A  and  FIG. 7B , a top and front view respectively of a fixed cross connector  300 . The fixed cross connector  300  comprises a cross connector rod hook  322  and a conical screw  302  at each end. The conical screw  302  retains a spinal rod  112 ,  114  in the respective cross connector rod hook  322 . The distance between the two cross connector rod hooks  322  may be varied to allow the fixed cross connector  300  to be attached to spinal rods  112 ,  114  at various lateral spacing. In selected embodiments the distance between the centers of the two cross connector rod hooks  322  is between approximately 10 mm and approximately 40 mm. In a further selected embodiment the distance between the centers of the two cross connector rod hooks  322  is between approximately 14 mm and approximately 36 mm. Non-limiting examples include a distance between the centers of the two cross connector rod hooks  322  of approximately 14 mm, approximately 16 mm, approximately 18 mm, approximately 20 mm, approximately 22 mm, approximately 24 mm, approximately 26 mm, approximately 28 mm, approximately 30 mm, approximately 32 mm, approximately 34 mm, and approximately 36 mm. 
     Referring to  FIG. 8 , an isometric view of a further embodiment of the fixed cross connector  300 . In this embodiment the ends of the fixed cross connector  300  are connected by a fixed cross connector extension rod  304 . The fixed cross connector extension rod  304  may be of varying lengths to provide a fixed cross connector  300  configured to attach to spinal rods  112 ,  114  at various lateral spacing. In selected embodiments the distance between the centers of the two cross connector rod hooks  322  is between approximately 10 mm and approximately 40 mm. In a further selected embodiment the distance between the centers of the two cross connector rod hooks  322  is between approximately 14 mm and approximately 36 mm. Non-limiting examples include a distance between the centers of the two cross connector rod hooks  322  of approximately 14 mm, approximately 16 mm, approximately 18 mm, approximately 20 mm, approximately 22 mm, approximately 24 mm, approximately 26 mm, approximately 28 mm, approximately 30 mm, approximately 32 mm, approximately 34 mm, and approximately 36 mm. The fixed cross connector extension rod  304  may also be curved or angulated to allow fixation to spinal rods  112 ,  114  which are not in parallel alignment. The conical screw receiving port  324  accepts a conical screw  302  for securing a spinal rod  112 ,  114  in the respective cross connector rod hook  322 . 
     Referring to  FIG. 9A ,  FIG. 9B , and  FIG. 9C , a front profile, top profile, and an isometric view respectively of a closed lateral connector  190 . The closed lateral connector  190  comprises a lateral connector rod  192 , a set screw receiving port  124 , and a closed rod receiving channel  122 . The lateral connector  190  may be affixed to a polyaxial screw  230  [shown in  FIG. 39 ] or a uniaxial screw with the lateral connector rod  192  disposed in the screw saddle  232 . The lateral connector rod  192  is sized to match a standard spinal rod  112 ,  114 . The lateral connector rod  192  is preferably circular and approximately 4.75 mm or approximately 5.5 mm in diameter. The lateral connector rod  192  may also be varying lengths. The lateral connector rod  192  is preferably approximately 15 mm to approximately 80 mm in length and more preferably approximately 20 mm to approximately 60 mm in length. Non-limiting examples include a lateral connector rod  192  with a length of approximately 20 mm, approximately 30 mm, approximately 40 mm, and approximately 60 mm. 
     Referring to  FIG. 10A , a front profile view of a bi-axial cross connector  330 . The bi-axial cross connector  330  comprises a first linkage  336 , a second linkage  334 , a pivot post  332 , a midline nut  338 , and a pair of conical screws  302 . The first linkage  336  and the second linkage  334  can extend along a first axis to lengthen the bi-axial cross connector  330 . Adjustment of the length along the first axis allows the bi-axial cross connector  330  to be affixed to spinal rods  112 ,  114  laterally spaced at any distance along a continuum. This is in contrast to a fixed cross connector  300 , wherein the spinal rods must be laterally spaced at approximately one of a finite number of predetermined distances. The first linkage  336  and second linkage  334  may also rotate relative to each other about the first axis. Rotation of the first linkage  336  and second linkage  334  about the first axis allows the bi-axial cross connector  330  to be affixed to spinal rods  112 ,  114  which are skewed in the sagittal plane. The first linkage  336  and the second linkage  334  are also angulated about a second axis perpendicular to the first axis. Angulation of the first linkage  336  and the second linkage  334  about the second axis allows the bi-axial cross connector  330  to be affixed to spinal rods  112 ,  114  which are skewed in the coronal plane. 
     Adjustment of the length of the bi-axial cross connector  330  along the first axis allows the bi-axial cross connector  330  to be affixed to spinal rods  112 ,  114  laterally spaced at any distance along a continuum within predetermined ranges. 
     Referring to  FIGS. 11A and 11B , the first linkage  336  comprises a cross connector rod hook  322 , a bi-axial cross connector extension rod  342 , and a bi-axial cross connector extension rod limiter  344 . Cross connector rod hook  322  comprises the same geometry as closed rod receiving channel  122  except the upper arc  410  is not present and a portion of middle arc  412  may also be not present. The bi-axial cross connector extension rod  342  is a round shaft with the bi-axial cross connector extension rod limiter  344  disposed on the end. The bi-axial cross connector extension rod limiter  344  helps prevent the bi-axial cross connector extension rod  342  from disengaging from the pivot post  332  during manipulation of the bi-axial cross connector  330 . The bi-axial cross connector extension rod  342  is preferably approximately 10 mm to approximately 40 mm in length and more preferably approximately 17 mm to approximately 32 mm in length. The bi-axial cross connector extension rod  342  is preferably approximately 3.5 mm to approximately 4.5 mm in diameter and more preferably approximately 3.9 mm to approximately 4.1 mm in diameter. For example, the bi-axial cross connector extension rod  342  may be 24 mm in length and 3.98 mm in diameter. 
     Referring to  FIG. 12A  and  FIG. 12B , a side profile and front profile respectively of the pivot post  332 . The pivot post  332  comprises a bi-axial cross connector extension rod channel  350 , a threaded post  352 , and a linkage retaining shoulder  354 . The bi-axial cross connector extension rod channel  350  is configured to allow the bi-axial cross connector extension rod  342  and the bi-axial cross connector extension rod limiter  344  to pass through unimpeded when the bi-axial cross connector extension rod is in contact with a first surface  356 . Conversely, the bi-axial cross connector extension rod channel  350  is configured to prohibit the bi-axial cross connector extension rod  342  and the bi-axial cross connector extension rod limiter  344  to pass through unimpeded when the bi-axial cross connector extension rod is in contact with a second surface  358 , as the bi-axial cross connector extension rod limiter catches on the pivot post  332 . The threaded post  352  comprises threads configured to engage with internal threads on the midline nut  338 . 
     The first surface  356  of the bi-axial cross connector extension rod channel  350  of the pivot post  332  preferably is an arc with a diameter of approximately 0.6 to approximately 1.4 mm larger than the diameter of the bi-axial cross connector extension rod  342 . The second surface  358  of the bi-axial cross connector extension rod channel  350  of the pivot post  332  preferably is an arc with a diameter of approximately 0.03 to approximately 0.30 mm larger than the diameter of the bi-axial cross connector extension rod  342 . For example, as in the previous example, the bi-axial cross connector extension rod  342  may be 3.98 mm in diameter and the diameter of the arc of the first surface  356  may be 4.98 mm and the diameter of the second surface  358  may be 4.02 mm. 
     Referring to  FIG. 13A  and  FIG. 13B , a front profile view and a top profile view respectively of the second linkage  334 . The second linkage  334  comprises a cross connector rod hook  322 , a conical screw receiving port  324  with conical screw receiving threads  326 , and a bi-axial cross connector extension plank  346  having a linkage retaining orifice  340 . The linkage retaining orifice  340  engages with the linkage retaining shoulder  354  of the pivot post  332 . The bi-axial cross connector extension plank  346  is a flat strip extending away from the conical screw receiving port  324  and cross connector rod hook  322 . The bi-axial cross connector extension plank  346  is preferably approximately 10 mm to approximately 40 mm in length and more preferably approximately 17 mm to approximately 32 mm in length. The length of the bi-axial cross connector extension plank  346  is the length of the thinned portion of the second linkage  334 . For example, the bi-axial cross connector extension plank  346  may be approximately 17 mm in length, approximately 18 mm in length, approximately 20 mm in length, approximately 24 mm in length, and approximately 32 mm in length. 
     When assembled, the midline nut  338  presses the second linkage  334  toward the linkage retaining shoulder  354  which in turn presses the second linkage into the bi-axial cross connector extension rod  342  which is passed through the bi-axial cross connector extension rod channel  350 . The compressive force of the midline nut  338 , in conjunction with frictional forces, prevent the bi-axial cross connector  330  from extending along the first axis, rotating about the first axis, or angulating about the second axis. 
     Referring again to  FIG. 10A , a front profile of the bi-axial cross connector  330  in an extended configuration. The bi-axial cross connector  330  can secure both the 5.5 mm diameter spinal rod  112  and the 4.75 mm diameter spinal rod  114 . The 5.5 mm diameter spinal rod  112  is shown in  FIG. 10A  in the cross connector rod hook  322  in an unsecured configuration as the conical screw  302  is not fully advanced and pressing the spinal rod into the cross connector rod hook. 
     Referring to  FIG. 10B , a top profile of the bi-axial cross connector  330  in a retracted configuration. The conical screw  302  has a hexalobular internal driving feature. 
     In an embodiment of the bi-axial cross connector  330 , the range of adjustment afforded by the different lengths of the bi-axial cross connector extension rod  342  and the bi-axial cross connector extension plank  346  allows for the bi-axial cross connector  330  to be adjusted from approximately 30 mm to approximately 70 mm spacing between the centerlines of spinal rods  112 / 114  disposed in the cross connector rod hooks  322 . In an embodiment of the bi-axial cross connector  330 , spacing between the centerlines of spinal rods  112 / 114  disposed in the cross connector rod hooks  322  may be adjusted from approximately 34 mm to approximately 37 mm. In a further embodiment of the bi-axial cross connector  330 , spacing between the centerlines of spinal rods  112 / 114  disposed in the cross connector rod hooks  322  may be adjusted from approximately 35 mm to approximately 39 mm. In a further embodiment of the bi-axial cross connector  330 , spacing between the centerlines of spinal rods  112 / 114  disposed in the cross connector rod hooks  322  may be adjusted from approximately 37 mm to approximately 43 mm. In a further embodiment of the bi-axial cross connector  330 , spacing between the centerlines of spinal rods  112 / 114  disposed in the cross connector rod hooks  322  may be adjusted from approximately 41 mm to approximately 51 mm. In a further embodiment of the bi-axial cross connector  330 , spacing between the centerlines of spinal rods  112 / 114  disposed in the cross connector rod hooks  322  may be adjusted from approximately 49 mm to approximately 67 mm. The combination of the multiple specifically disclosed embodiments of the bi-axial cross connector  330  allows for a bi-axial cross connector  330  to be selected suitable for securing spinal rods  112 / 114  spaced anyplace along the continuum of approximately 34 mm to approximately 67 mm. 
     Referring to  FIG. 14A , an embodiment of a bi-axial cross connector  330 . The bi-axial cross connector  330  comprises a first linkage  336 , a second linkage  334 , a midline locking post  370 , a midline locking screw  339 , and a pair of conical screws  302 . The first linkage  336  and the second linkage  334  can extend along a first axis to lengthen the bi-axial cross connector  330 . Adjustment of the length along the first axis allows the bi-axial cross connector  330  to be affixed to spinal rods  112 ,  114  laterally spaced at any distance along a continuum. This is in contrast to a fixed cross connector  300 , wherein the spinal rods must be laterally spaced at approximately one of a finite number of predetermined distances. The first linkage  336  and second linkage  334  may also rotate relative to each other about the first axis. Rotation of the first linkage  336  and second linkage  334  about the first axis allows the bi-axial cross connector  330  to be affixed to spinal rods  112 ,  114  which are skewed in the sagittal plane. The first linkage  336  and the second linkage  334  are also angulated about a second axis perpendicular to the first axis. Angulation of the first linkage  336  and the second linkage  334  about the second axis allows the bi-axial cross connector  330  to be affixed to spinal rods  112 ,  114  which are skewed in the coronal plane. 
     Referring to  FIGS. 14A and 14B , the first linkage  336  comprises a cross connector rod hook  322 , a bi-axial cross connector extension rod  342 , and a bi-axial cross connector extension rod limiter  344 . Cross connector rod hook  322  comprises the same geometry as closed rod receiving channel  122  except the upper arc  410  is not present and a portion of middle arc  412  may also be not present. The bi-axial cross connector extension rod  342  is a round shaft with the bi-axial cross connector extension rod limiter  344  disposed on the end. In an embodiment, the bi-axial cross connector extension rod limiter  344  is a pin projecting beyond the diameter of the bi-axial cross connector extension rod  342 . The bi-axial cross connector extension rod limiter  344  helps prevent the bi-axial cross connector extension rod  342  from disengaging from the midline locking post  370  during manipulation of the bi-axial cross connector  330 . The bi-axial cross connector extension rod limiter  344  is preferably installed in the bi-axial cross connector extension rod  342  subsequent to passing though the midline locking post  370  during the manufacturing and assembly process. The bi-axial cross connector extension rod limiter  344  is preferably sized such that removal of the bi-axial cross connector extension rod  342  from the midline locking post  370  is not feasible. 
     Referring to  FIG. 15 , an embodiment of the midline locking post  370  used in the embodiment of the bi-axial cross connector  330  shown in  FIGS. 14A-14C  is shown. The midline locking post  370  comprises a bi-axial cross connector extension rod passage  374 , a threaded locking screw receiver  376 , and a locking post retention flange  372 . The bi-axial cross connector extension rod passage  374  is configured to allow the bi-axial cross connector extension rod  342  to pass through unimpeded but prevent the bi-axial cross connector extension rod limiter  344  from passing through. The threaded locking screw receiver  376  comprises internal threads configured to engage with external threads on the midline locking screw  339 . The locking post retention flange  372  retains the midline locking post  370  in the second linkage prior to securing with the midline locking screw. 
     The second linkage  334  comprises a cross connector rod hook  322 , a conical screw receiving port  324  with conical screw receiving threads  326 , and a bi-axial cross connector extension plank  346  having a linkage retaining orifice  340 . The linkage retaining orifice  340  has a linkage retention flange  378  disposed around the periphery of the linkage retaining orifice  340 . The linkage retention flange  378  engages with the locking post retention flange  372 . 
     When assembled, the midline locking screw  339  pulls the midline locking post  370  upward. The movement of the midline locking post  370  moves the first linkage  336  upward as well and compresses the first linkage  336  against the second linkage  334 . The compressive force of the midline locking screw  339  and the midline locking post  370  pulling the second linkage  334  and the first linkage  336  together, in conjunction with frictional forces, prevent the bi-axial cross connector  330  from extending along the first axis, rotating about the first axis, or angulating about the second axis. 
     Referring to  FIG. 39 , a front profile of a polyaxial screw  230 . The polyaxial screw  230  comprises a screw saddle  232  for receiving a spinal rod  112 ,  114  or lateral connector rod  192  for example. The rod receiving geometry of the screw saddle  232  is envisioned being configured to match the rod receiving geometry of the open rod receiving saddle  222  of the open laminar hook  220  for acceptance of multiple diameter spinal rods including a 5.5 mm diameter spinal rod  112  or a 4.75 mm diameter spinal rod  114 . Uniaxial screws with a similar rod receiving geometry for securing multiple diameter spinal rods  112 ,  114  are also envisioned. 
     While reference is made throughout this disclosure to dual-diameter connectors, dual-diameter hooks, and dual-diameter screws, it is envisioned that the technique used to allow acceptance of two diameters of rods can be modified to allow three or more diameters of rods. 
     Referring to  FIGS. 16A-16C , a rod reduction device  600  is shown.  FIG. 16C  is a longitudinal cross sectional view of reduction device  600  taken along section line, N-N. In the illustrative embodiment shown, reduction device  600  includes an housing tube  501 , advancing knob  502 , reduction rod  503 , cap  504 , inner tube  505 , retractor sleeve  506 , reduction sleeve  507 , release ring  508 , release ring screw  509 , fingers  510 , finger springs  511 , spring hinge pins  513 , finger cam pins  514 , finger hinge pins  515 , weld sleeve  516 , release spring  517 , a plurality of ball bearings  518 , and finger cover  519 . When assembled together, these components form reduction device  600 , which comprises a hollow, cylindrical shaped assembly having a first end  602  and a second end  604 . First end  602  includes a first assembly opening  606 , and second end  604  includes a second assembly opening  608 . Each of the components set forth above will be individually described below herein and shown in separate figures. In addition, it will be shown and described below herein how each of the components of reduction device  600  are interconnected and, once assembled, how reduction device  600  works in operation. 
     Referring to  FIGS. 17A-17C , housing tube  501  of reduction device  600  is shown. Housing tube  501  comprises a hollow, housing tube body  520 , having a housing tube first end  522  and a second end  524  opposite housing tube first end  522 . Housing tube first end  522  is shaped. In this example, housing tube first end  522  has a hexagonal shape. Additionally, in this example housing tube first end  522  comprises housing tube engagement slots  521 . Also, housing tube first end  522  includes internal housing tube threads  525 . Housing tube first end  522  also comprises a first housing tube opening  616 , and second end  524  comprises a second housing tube opening  618 . Housing tube body  520  includes an internal housing tube channel  619  that connects first and second outer tube openings  616 / 618 , respectively. Housing tube body  520  includes at second end  524  two diametrically opposed housing tube slots  526 , each running from the second end  524  longitudinally along at least a portion of housing tube body  520 . Housing tube slots  526  further include a narrow portion  527  connected to a wide portion  528 . 
     Housing tube body  520  also includes diametrically opposed second housing tube slots  529  disposed at second end  524 , but circumferentially offset 90° from housing tube slots  526 . Second housing tube slots  529  run from second end  524  longitudinally along at least a portion of housing tube body  520 . Optionally, housing tube body  520  includes a gripping section such as a medium diamond knurl  523  etched into a surface of housing tube body  520 . 
     Referring to  FIGS. 18A and 18B , advancing knob  502  of reduction device  600  is shown. Advancing knob  502  comprises a hollow, advancing knob body  530 , having an advancing knob first end  532  and an advancing knob second end  534  opposite advancing knob first end  532 . Advancing knob first end  532  is shaped. In this example, advancing knob first end  532  has a hexagonal shape. Advancing knob body  530  also includes an advancing knob annular ring  538  extending therefrom and disposed between a midpoint of advancing knob body  530  and advancing knob first end  532 . Advancing knob body  530  includes internal advancing knob threading  531  on a portion of its internal surface. In this example, internal advancing knob threading  531  is disposed from advancing knob second end  534  to just beyond the midpoint of advancing knob body  530  along the internal surface of advancing knob body  530 . Advancing knob annular ring  538  further includes an advancing knob bearing well  539  that is disposed within advancing knob annular ring  538  annularly about the circumference of advancing knob body  530 . Advancing knob first end  532  also comprises a first advancing knob opening  626 , and advancing knob second end  534  comprises a second advancing knob opening  628 . Advancing knob body  530  includes an internal advancing knob channel  629  that connects first and second knob openings  626 / 628 , respectively. 
     Referring to  FIGS. 19A and 19B , reduction rod  503  of reduction device  600  is shown. Reduction rod  503  comprises a hollow, cylindrical shaped reduction rod body  540 , having a first reduction rod end  542  and a second reduction rod end  544  opposite first reduction rod end  542 . First reduction rod end  542  comprises a first reduction rod opening  543 , and second reduction rod end  544  comprises a second reduction rod opening  545 . Reduction rod body  540  includes an internal reduction rod channel  547  that connects first and second reduction rod openings  543 / 545 , respectively. First reduction rod end  542  comprises external reduction rod threads  541  disposed on a portion of the outer surface of reduction rod body  540 . A first extender  548   a  extends radially from the outer surface of reduction rod body  540  adjacent second reduction rod end  544 . A second extender  548   b  extends radially from the outer surface of reduction rod body  540  adjacent second reduction rod end  544  and diametrically opposed to first extender  548   a . Reduction rod body  540  also comprises an annular bulbous portion  546  disposed adjacent the midpoint of reduction rod body  540 , closer to second reduction rod end  544 . Annular bulbous portion  546  has an increased outer diameter compared to the rest of reduction rod body  540 . 
     Referring to  FIG. 20 , cap  504  of reduction device  600  is shown. Cap  504  comprises a hollow, cylindrical-shaped cap body  550 , having a first cap end  552  and a second cap end  554  opposite first cap end  552 . First cap end  552  comprises a first cap opening  556 , second cap end  554  comprises a second cap opening  558 , and cap body  550  includes an internal cap channel  557  that connects first cap opening  556  to second cap opening  558 . Also, second cap end  554  includes external cap threads  551  disposed on the outer surface of cap body  550  and a substantially hemispherical channel disposed around the second cap opening  558  to form a cap bearing well  555 . 
     Referring to  FIGS. 21A-21D , inner tube  505  of reduction device  600  is shown. Inner tube  505  comprises a hollow, cylindrical shaped inner tube body  560 , having a first inner tube end  562  and a second inner tube end  564  opposite first inner tube end  562 . First inner tube end  562  comprises a first inner tube opening  566 , and second inner tube end  564  comprises a second inner tube opening  568 . Inner tube body  560  includes an internal rod channel  567  that connects first and second inner tube openings  566 / 568 , respectively. As shown in  FIGS. 21A and 21C , inner tube  505  comprises a first inner tube slot  565   a  and a second inner tube slot  565   b  diametrically opposed to first inner tube slot  565   a . Inner tube body  560  also comprises a first inner tube channel  569   a  and a second inner tube channel  569   b  as shown in  FIG. 21B . Inner tube body  560  comprises a first finger slot  561   a  and a second finger slot  561   b  diametrically opposed to first finger slot  561   a  disposed therein for receiving the fingers  510 . 
     Also, a first left spring pocket  906   a  and a first right spring pocket  904   a  are disposed within inner tube body  560 , adjacent to and on opposite sides of first finger slot  561   a , for receiving finger springs  511 . Similarly, a second left spring pocket  906   b  and a second right spring pocket  904   b  are disposed within inner tube body  560 , adjacent to and on opposite sides of second finger slot  561   b , for receiving finger springs  511 . In addition, inner tube body  560  comprises finger pin apertures  900  for receiving finger hinge pins  515 , and spring pin apertures  902  for receiving spring hinge pins  513 . 
     Referring to  FIGS. 22A-22C , retractor sleeve  506  of reduction device  600  is shown. Retractor sleeve  506  comprises a hollow, cylindrical-shaped retractor sleeve body  570 , having a first retractor sleeve end  572  and a second retractor sleeve end  574  opposite first retractor sleeve end  572 . Retractor sleeve  506  further comprises a first retractor sleeve arm  571  extending longitudinally away from first retractor sleeve end  572  of retractor sleeve body  570  and a second retractor sleeve arm  573  extending longitudinally away from first retractor sleeve end  572 , but diametrically opposed to first retractor sleeve arm  571  along the retractor sleeve body  570 . Additionally, retractor sleeve  506  comprises a third retractor sleeve arm  575  extending longitudinally away from second retractor sleeve end  574  of retractor sleeve body  570  and a fourth retractor sleeve arm  577  extending longitudinally away from second retractor sleeve end  574 , but diametrically opposed to third retractor sleeve arm  575  along retractor sleeve body  570 . Additionally, a release spring support ring  578  is formed by a lip disposed around the interior periphery of the retractor sleeve body  570  between the first retractor sleeve end  572  and the second retractor sleeve end  574 . The release spring support ring  578  abuts the release spring  517  upon assembly and prevents translation of the release spring. 
     Referring to  FIG. 23 , reduction sleeve  507  of reduction device  600  is shown. Reduction sleeve  507  comprises a hollow, cylindrical shaped reduction sleeve body  580 , having a first reduction sleeve end  582  and a second reduction sleeve end  584  opposite first reduction sleeve end  582 . First reduction sleeve end  582  comprises a first reduction sleeve opening  586 , and second reduction sleeve end  584  comprises a second reduction sleeve opening  588 . Reduction sleeve body  580  includes an internal reduction sleeve channel  587  that connects first and second reduction sleeve openings  586  and  588 , respectively. As shown in the figures, reduction sleeve  507  comprises reduction rod engagement slots  581  running from first reduction sleeve end  582  longitudinally along a portion of reduction sleeve body  580 . It is envisioned in an embodiment that there are two reduction rod engagement slots  581  disposed along reduction sleeve body  580  diametrically opposed to each other. 
     Along the same sides of reduction sleeve body  580  as reduction rod engagement slots  581 , reduction sleeve viewing apertures  583  are positioned adjacent to and/or near second reduction sleeve end  584 . Reduction sleeve body  580  also comprises a rod engagement radius  585  disposed therein and at the distal end of second reduction sleeve end  584  and another rod engagement radius  585  disposed therein and at the distal end of second reduction sleeve end  584 . Reduction sleeve body  580  further comprises reduction sleeve radial reductions  589  disposed therein and at the distal end of second reduction sleeve end  584 , offset 90° from rod engagement radii  585 . 
     Referring to  FIGS. 24A and 24B , release ring  508  of reduction device  600  is shown. Release ring  508  comprises a hollow, cylindrical shaped release ring body  590 , having a first release ring end  592  and a second release ring end  594  opposite first release ring end  592 . First release ring end  592  comprises a first release ring opening  596 , and second release ring end  594  comprises a second release ring opening  598 . Release ring body  590  includes an internal release ring channel  597  that connects first and second release ring openings  596 / 598 , respectively. Additionally, release ring  508  may comprise a first release ring feature  591  disposed within release ring body  590  about the circumference of release ring body  590  and a second release ring feature  593  disposed within release ring body  590  about the circumference of release ring body  590 , adjacent to first release ring feature  591 . Release ring  508  may also comprise at least one release ring screw aperture  595  disposed within release ring body  590  for receiving release ring screw  509 . In an embodiment release ring  508  comprises two diametrically opposed release ring screw apertures  595  for receiving release ring screws  509 . 
     Referring back to  FIG. 16C , reduction device  600  comprises a two fingers  510  diametrically opposed to each other. Now referring to  FIGS. 25A-25D , finger  510  comprises a finger body  660  having a finger first end  662  and a finger second end  664  opposite finger first end  662 . Finger second end  664  comprises a finger hook  661  having a finger hook undercut  663 . In one example, finger hook undercut  663  may comprise any angle α above an acute angle. In another example, finger hook undercut  663  may comprise an angle α from about 20° to 90°, from about 30° to about 80°, from about 45° to about 75°. In still another example, finger hook undercut  663  may comprise an angle α from about 40°, about 50°, about 60°, about 70°, about 80°, or about less than 90°. 
     Finger body  660  comprises a finger aperture  665  disposed therethrough. Finger body  660  also comprises a first finger extension  670  extending longitudinally from finger body  660  and a second finger extension  672  extending longitudinally from finger body  660  opposite to and spaced apart from first finger extension  670 . First finger extension  670  comprises a first finger stop  676  disposed at finger first end  662  extending transversely from finger body  660 . Second finger extension  672  comprises a second finger stop  678  disposed at finger first end  662  extending transversely from finger body  660 . 
     Referring specifically to  FIG. 25D  along with  FIGS. 25A-25C , first and second finger extensions  670  and  672  each comprise a finger slot  680 . The finger slot  680  comprises three zones: a first zone A, a transition zone B and a third zone C. In particular, first zone A of the slot comprises a width that is configured and sized such that when finger cam pin  514  is positioned within first zone A, finger cam pin  514  forms a running and sliding fit within first zone A. As example, the width of first zone A is defined by upper slot guide  682  and lower slot guide  684  and is sufficient enough to permit finger cam pin  514  to slide within first zone A, but not enough to permit substantial lateral movement transverse to the sliding movement of finger cam pin  514  within first zone A. Substantial lateral movement is defined as movement greater than 1/10 th  the diameter of the finger cam pin  514 . Third zone C of finger slot  680  is configured and sized such that it has a width to form a clearance fit with finger cam pin  514 . As an example, third zone C is configured to have a funnel shape such that its shape and size creates a smooth transition from the first zone&#39;s width to the maximum width of third zone C. Transition zone B provides a smooth transition from the width of the first zone A (i.e., running and sliding fit) to the width of third zone C (i.e., clearance fit). In operation, finger cam pins  514  are positioned within finger slots  680  such that the finger cam pins engage and run along respective inner finger cam surfaces  688  of finger slots  680 . This action will be explained in greater detail below herein. 
     As such, when fingers  510  are in the spring-biased radially inwardly position (i.e., a normal position), finger cam pin  514  are positioned in the third zone C formed by finger cam  686 . When reduction device  600  is moved such that second assembly opening  608  is slid over a tulip head of a polyaxial screw  230  or a uniaxial pedicle screw, the tulip head, when inserted into second assembly opening  608 , engages the finger hooks  661  of fingers  510  and forces and/or pushes them outwardly against the force of finger springs  511 . As the fingers  510  are pushed outwardly, the fingers pivot about finger hinge pins  515  such that finger first ends  662  move radially inward, causing finger cam pins  514  (which are still positioned within third zone C and engaged against respective inner finger cam surfaces  688  to move away from engagement with respective inner finger cam surfaces  688  within third zone C up and, optionally to engagement with respective outer finger cam surface  689 . The clearance fit of third zone C provides the clearance to permit the fingers  510  to pivot within rod reduction device  600  in order to permit the tulip head of pedicle screw  230  to insert into second assembly opening  608  of rod reduction device  600 . 
     Referring to  FIGS. 26A-26D , weld sleeve  516  is shown. Weld sleeve  516  comprises a hollow, cylindrical-shaped weld sleeve body  730  having a first weld sleeve end  732  and a second weld sleeve end  734 . Disposed at first weld sleeve end  732 , body comprises a first weld sleeve opening  736 , a second weld sleeve opening  738 , and an internal weld sleeve channel  737  connecting the two openings. Weld sleeve body  730  comprises diametrically opposed retractor sleeve arm engagement slots  733 . Second weld sleeve end  734  includes a weld sleeve flange  731 . 
     Referring to  FIG. 27 , finger cover  519  of reduction device  600  is shown having a finger cover body  750 . Finger cover body  750  includes a finger cover aperture  752  and is curved to closely match the curvature of one or more of the other components. 
     Referring to  FIGS. 28A-30C  as well as all the figures previously referenced, the assembly of rod reduction device  600  will be described. As shown in  FIGS. 28A and 28B , first and second finger extensions  670  and  672  of finger  510  are inserted about third retractor sleeve arm  575  of retractor sleeve  506 . Finger cam pin  514  is inserted through finger slot  680  of first finger extension  670 , a third retractor sleeve arm cross pin aperture  1000   a  disposed within third retractor sleeve arm  575 , and through finger slot  680  of second finger extension  672 . Similarly, first and second finger extensions  670  and  672  of finger  510  are inserted about fourth retractor sleeve arm  577  of retractor sleeve  506 . A finger cam pin  514  is also inserted through finger slot  680  of second finger extension  672 , a fourth retractor sleeve arm cross pin aperture  1000   b  disposed within fourth retractor sleeve arm  577 , and through finger slot  680  of second finger extension  672 . 
     Referring to  FIGS. 29A and 29B , the retractor sleeve  506  and finger  510  assembly is inserted over second inner tube end  564  of inner tube body  560  such that fingers  510  slide into first and second finger slots  561   a / 561   b . Next, as an example, finger springs  511  are placed within first left spring pocket  906   a  and first right spring pocket  904   a . One end of finger spring  511  is abutted against a surface of first right spring pocket  904   a  and the opposite end of finger spring  511  is abutted against first finger stop  676 . One end of finger spring  511  is abutted against a surface of first left spring pocket  906   a  and the opposite end of finger spring  511  is abutted against second finger stop  678 . Finger springs  511  are aligned with spring pin apertures  902  and then spring hinge pins  513  are press fit into the aligned respective spring pin apertures  902  and spring coils. Also, finger aperture  665  is aligned with finger pin aperture  900  and then finger hinge pin  515  is press fit into and through such aligned apertures. The same assembly is performed for the second finger  510 . Once assembled, the pins are welded in place using conventional welding processes such as a laser welding process. Pin ends are then polished to be flush with outer surface of inner tube  505 . 
     In such a configuration, finger springs  511  bias fingers  510  radially inward toward a central longitudinal axis of reduction device  600  such that finger hook undercuts  663  of fingers  510  engage tulip head pockets  236  disposed within and on opposite sides of the tulip head  234 . Tulip head pockets  236  include respective tulip head undercuts  238  that correspond to and engage with finger hook undercuts  163  as shown in  FIG. 32B  for example. 
     Release spring  517  is slid over second inner tube end  564  of inner tube body  560  of inner tube  505  as shown in  FIG. 29B . Next, align retractor sleeve arm engagement slots  733  of weld sleeve  516  with respective first and second arms  571 / 573  of retractor sleeve  506  and then slide weld sleeve  516  over second inner tube end  564  of inner tube body  560  until weld sleeve flange  731  of weld sleeve  516  is flush with retractor sleeve body  570  as shown in  FIGS. 29A and 29B . Finger cover bodies  750  are fit into respective first and second finger slots  561   a / 561   b  as shown in  FIGS. 29A and 29B  and then may be connected to inner tube body  560  in any number of conventional means such as, for example, welding (e.g., laser welding around periphery of finger cover), snap-fit, etc. 
     Referring to  FIGS. 16A-16C and 530 , release ring  508  is slid over housing tube  501 . Reduction rod  503  is inserted into housing tube  501  as shown in  FIG. 30  such that first and second extenders  548   a / 548   b  of reduction rod  503  are inserted through and extend from housing tube slots  526  of housing tube  501 . Next, retractor sleeve  506 /inner tube  505 /weld sleeve  516 /fingers  510  assembly shown in  FIGS. 29A and 29B  is inserted into second end  524  of housing tube  501  such that first and second arms  571 / 573  of retractor sleeve  506  align with and slide into second housing tube slots  529  of housing tube  501  as shown in  FIG. 30 . Weld sleeve  516  is connected to housing tube  501  via conventional connection methods, including welding. Additionally, first and second screws  509   a / 509   b  are inserted through and threadably engaged with release ring  508 , housing tube  501 , and respective first and second retractor sleeve arms  571 / 573 . Engagement with first retractor sleeve arm  571  and second retractor sleeve arm  573  is through first retractor sleeve arm screw aperture  579   a  and second retractor sleeve arm screw aperture  579   b  respectively. 
     Referring to  FIGS. 30A-30C , the final assembly of reduction device  600  is shown. Specifically, reduction sleeve  507  is slid over second end  524  of housing tube  501  such that reduction rod engagement slots  581  abut against and are welded to first and second extenders  548   a  and  548   b  of reduction rod  503 . Advancing knob  502  is inserted into housing tube first end  522  of housing tube  501 , a plurality of ball bearings  518  are disposed into advancing knob bearing well  539  of advancing knob annular ring  538  of advancing knob  502 , and then cap  504  is threadably engaged to housing tube first end  522  of housing tube  501 . The cap bearing well  555  interfaces with the ball bearings  518  opposite the advancing knob bearing well  539 . 
     Referring to  FIGS. 33A and 33B , a reduction adaptor  1100  is shown. Reduction adaptor  1100  includes at a first end, an internal hexagonal head (e.g., similar to a socket head), and at a second end, an external hexagonal end, opposite the first end. It is understood that other types, configurations, and shapes of heads can be used. The first end can be inserted onto advancing knob first end  532  of advancing knob  502  to engage advancing knob engagement head  536  of advancing knob  502  as shown in  FIGS. 33A and 33B . 
     Referring to  FIGS. 40A-40C , an embodiment of pedicle screw  230 , size and shape of the pedicle screw  230  and the second assembly opening  608  of the reduction device  600  substantially match. When the tulip head  234  of the pedicle screw  230  is inserted into second assembly opening  608  of second end  604  of device  600  the pedicle screw  230  is engaged with minimal freedom of movement. As such, in one embodiment, the clocking of reduction device  600  to the tulip head  234  of the pedicle screw  230  is from about 0° to about 20°, from about 0° to about 15°, from 0° to about 10°, or from 0° to about 5°. As shown, fingers  510  are engaging respective tulip head pockets  236  of the tulip head  234 . The tulip head  234  and corresponding second assembly opening  608  of device  600  has a cross sectional shape that is substantially rectilinear, having rounded corners and curved sidewalls. 
     Referring to  FIG. 31 , a set screw driver  850  is shown. Set screw driver  850  includes a set screw driver body  852  having a set screw engagement head  854  and a driver head  856 . In this example, set screw engagement head  854  includes an external head that has a star-shape which matches and/or corresponds with the internal star-shaped head of the set screw. Driver head  856  comprises a substantially square-shaped head. However, it is understood that the heads of the driver and/or the set screw head can have either internal and/or external heads having any shape, size, and/or configuration. 
     A method for reducing a rod within a tulip head of a pedicle screw using the reduction device  600  is shown and described herein.  FIGS. 32A-34C  are sequential steps in the process of this method for reducing a spinal rod  112 / 114  into a tulip head  234  of a pedicle screw  230 . Such a method may be part of a method for correcting or ameliorating spinal aberrations or defects such as, for example, scoliosis, lordosis, and/or kyphosis. 
       FIGS. 32A-34C  show the tulip head of pedicle screw  230  fully inserted into second assembly opening  608  of reduction device  600  and in locked engagement, i.e., fingers  510  are fully inserted into respective tulip head pockets  236  on opposite sides of the tulip head  234  such that finger hook undercuts  663  of the fingers  510  are engaged with respective tulip head undercuts  238  of the tulip head pockets  236  of the tulip head  234 . In the embodiment shown in  FIGS. 40A-40C , the tulip head pockets  236  of the tulip head  234  do not extend transversely all the way across the tulip head. Thus, in this illustrative example, the tulip head pockets  236  have an upper wall which includes the tulip head undercut  238 , a lower wall, and two opposed side walls. However, it is understood that other configurations may be utilized such as, for example, no side walls and/or bottom wall. 
     When release ring  508  is pulled toward first end  602  of device  600 , it pulls retractor sleeve  506  respective toward first end  602  which causes finger cam pins  514  to slide along inner finger cam surfaces  688  from third zone C through transition zone B and into first zone A, pulling fingers  510  radially outwardly from the tulip head. When the finger cam pins  514  have slide into zone C, fingers  510  are moved into the unlock position, disengaging finger hook undercuts  663  from the corresponding tulip head undercuts  238  of the tulip head pockets  236  of the tulip head  234 . In this unlocked position, the tulip head  234  may be removed from the reduction device  600 . 
     Referring to  FIGS. 35A and 35B , an embodiment of a rod reduction assembly  450  is shown. Advancing wheel  456  is in threaded engagement with outer reducer shell  454 . Rotation of advancing wheel  456  forces movement of reduction arm  452  relative to the outer reducer shell  454 . 
     Referring to  FIGS. 36A and 36B , an embodiment of a provisional locking instrument  360  is shown. The provisional locking instrument  360  is inserted into the central shaft of the rod reduction assembly  450  and provisional locking instrument threads  368  are engaged with internal rod reduction threads  458 . The threaded engagement advances the provisional locking assembly through the rod reduction assembly  450 . The provisional locking instrument  360  further comprises a locking sheath  362  which engages the tulip head  234  of a pedicle screw  230  advances the tulip head undercuts  238  against flanged catches of the reduction arm  452 . As the provisional locking instrument  360  is advanced, the locking sheath  362  engages the tulip head  234  and ceases advancing. Continued advancing of the provisional locking instrument  360  exposes polyaxial locking tines  364  which engage the screw shaft locking mechanism of the pedicle screw  230 . The polyaxial locking tines  364  are generally concealed by the locking sheath  362  which is held in a forward position by an advancing spring  366 . 
     Referring to  FIGS. 37A-38 , an embodiment of a pedicle screw inserter  380  is shown. The pedicle screw inserter  380  is used to insert a pedicle screw, for example a polyxial screw  230 , into a patient. The pedicle screw inserter  380  comprises a central tightening shaft  382 , a handle  384 , a friction sleeve  386 , and a screw head engagement sleeve  388 . The central tightening shaft  382  has a driver tip  394  shaped to match the drive head of the pedicle screw shaft. For example. The driver tip  394  may be a hexalobe. The screw head engagement sleeve  388  has screw head engagement threads  390 . The screw head engagement threads mate with the internal threads of a pedicle screw to secure the screw head engagement sleeve  388  and a pedicle screw together. The handle  384  and friction sleeve  386  allow for free rotation of the central tightening shaft  382 . 
     To insert a pedicle screw the screw head engagement sleeve  388  is engaged with the head of a pedicle screw. The driver tip  394  of the central tightening shaft  382  is aligned with the mating feature of the pedicle screw. The friction sleeve  386  and handle  384  are moved along the central tightening shaft until the friction sleeve interlocks with the head of the pedicle screw as shown in  FIG. 38 . The central tightening shaft  382  is rotated which rotates the shaft of the pedicle screw through the engagement with the driver tip  394 . The interlock between the friction sleeve  386  and the head of the pedicle screw helps prevent the screw head engagement sleeve from unthreading during the pedicle screw insertion process. The friction sleeve  386  and central tightening shaft  382  rotate in unison as they are both engaged with the head of the pedicle screw. 
     An exemplary method of therapy for use of the present devices is described as follows: 
     Initially, the area of implantation is surgically approached. 
     For a pedicle screw correction technique, a thoracic facetectomy is performed. The facet joints are cleaned and rongeurs are used to perform a partial inferior articular process osteotomy. This is done to enhance visualization. 3 mm to 5 mm of the inferior facet is removed and the articular cartilage of the superior facets is removed, except for on the lowest vertebra to be instrumented. This allows for the intraoperative localization of the thoracic pedicle screw starting points and enhances fusion. 
     The pedicles are subsequently prepared. A pedicle awl or burr is used to create a 3 mm deep posterior cortical breach. The pedicle awl may be advanced by gently twisting the handle with light pressure. A pedicle blush may be visualized suggesting entrance into the cancellous bone at the base of the pedicle but the blush may not be evident when preparing small pedicles due to the limited intrapedicular cancellous bone. When no pedicle blush is visualized, use a straight or curved pedicle probe, a Lenke probe for example, to search in the cortical breach for the soft, funnel-shaped cancellous bone, which indicates the entrance to the pedicle. This procedure should be performed with the tip of the pedicle probe pointed laterally to avoid perforation of the medial cortex. Gripping the sides of the handle to avoid applying too much ventral pressure, the tip of the probe is inserted approximately 2 mm to approximately 25 mm. The probe is oriented so that the flat surface of the probe is in the same plane as the curve of the pedicle, then removed and reinserted with the tip pointed medially. The probe is advanced to the desired depth and rotated approximately 180° to ensure adequate room for a screw. The feeler probe is advanced to the base of the hole, alternatively called the floor, to confirm five distinct bony borders. The five bony borders being a floor and four walls (medial, lateral, superior, and inferior). When necessary, bone wax or other hemostatic agent may be placed in the pedicle hole to limit bleeding, and then the probe may be repositioned with a more appropriate trajectory. 
     The pedicle is undertapped for the appropriate screw size. After the pedicle is undertapped a flexible feeler probe may be used to verify presence of threads in the tapped hole. To measure the length of the hole, a feeler probe is advanced to the floor of the hole and a hemostat is clamped to the feeler probe at the point where it exits the pedicle. The appropriate screw diameter and length may subsequently be selected based on both preoperative measurement and intraoperative observation. The same technique is repeated for each of the remaining pedicles that need to be instrumented. 
     Roentgenographic assistance using plain radiographs or fluoroscopy may be utilized to ensure proper screw trajectory. Pedicle markers are placed into the holes of the pedicles and a lateral view is obtained. An anterior-posterior view may also be obtained. 
     Pedicle screws  230  are placed in each prepared pedicle. Selection of uniaxial or polyaxial screws  230  is at the discretion of the surgeon with both options being anticipated. The screws should be advanced slowly through the pedicle to ensure proper tracking. The pedicle screws  230  should be placed at every segment that allows free passage of a pedicle screw on the correction side of the spine and every third or fourth level on the supportive side. At the proximal and distal end of the supportive side at least two screws should be inserted. Addition of more screws will result in greater construct rigidity. Upon placement of the screws they should be checked radiographically to ensure intraosseous screw placement. Should it be determined that a pedicle is too narrow to cannulate, alternate fixation methods such as hooks  210 ,  220 , wires or tapes may be used. 
     Once correct pedicle screw placement has been verified radiographically, the spinal rods  112 ,  114  are prepared. The spinal rods  112 ,  114  are measured and contoured in the sagittal and coronal planes. When contouring, the spinal rods  112 ,  114  may be clamped at both ends with rod grippers to help prevent the rod from rotating. 
     Once prepared to the proper contour and length, the first rod is placed into the previously inserted screws. To reduce the rod and seat it into each previously placed pedicle screw a rocker, a rod reduction assembly  450 , or a reduction device  600  may be used. The rocker method is an effective method for reducing the rod into the implant when only a slight height difference exists between the rod and the implant saddle. To reduce the rod using the rocker method, the sides of the implant are grasped with the rocker cam above the rod. The rocker is levered backwards over the rod to seat the rod into the saddle of the implant. A set screw is subsequently placed and provisionally tightened to hold the rod in place. 
     For reduction of the rod using the rod reduction assembly  450 , with the pedicle screw and rod in place the rod reduction assembly is applied over the head of the screw. The provisional locking instrument  360  is inserted down the tube of the rod reduction assembly  450  and threaded down to engage the provisional locking feature. Alternatively, the provisional locking instrument  360  may be inserted down the tube of the rod reduction assembly  450  and partially threaded down prior to affixing the rod reduction assembly to the screw head. The rod is then reduced by turning the advancing wheel  456  of the rod reduction assembly  450 . If greater torque is required to reduce the rod, a reduction adaptor  1100  attached to an axial or torque limiting T-handle may interface with the advancing wheel  456  of the rod reduction assembly  450 . The provisional locking instrument is subsequently removed as the rod reduction assembly has taken over the provisional lock engagement. A set screw driver  850  is used to introduce a set screw. The set screw is passed down the central cavity of the rod reduction assembly  450  until it bottoms out on the screw threads. To avoid cross threading of the set screw, the set screw is turned counterclockwise until a click is felt and then turned clockwise to tighten. 
     For reduction of the rod using the rod reduction device  600 , with the pedicle screw and rod on place the red reduction device is applied over the tulip head  234  of the screw. The fingers  510  of the rod reduction device  600  engage the tulip head pockets  236  of the pedicle screw tulip head  234 . The rod is then reduced by turning the advancing knob  502  of the rod reduction device  600 . If greater torque is required to reduce the rod, a reduction adaptor  1100  attached to an axial or torque limiting T-handle may interface with the advancing knob  502  of the rod reduction device  600 . A set screw driver  850  is used to introduce a set screw. The set screw is passed through the first assembly opening  606  of the rod reduction device  600  until it bottoms out on the screw threads. To avoid cross threading of the set screw, the set screw is turned counterclockwise until a click is felt and then turned clockwise to tighten. 
     While leaving the set screws loose or only locked at one end, the spinal rod  112 ,  114  is slowly straightened using tubular benders. Fully straightening the spinal rod  112 ,  114  may require several passes. 
     Once the contoured rod and all the set screws have been placed, the contoured rod is rotated into its final position. The rotation must be done slowly to prevent rapid neurologic changes and/or injury to the spinal cord. Using two rod holders the contoured rod is rotated into the desired position. The apical set screws are tightened and compression or distraction may be performed. During all the correction maneuvers the screw and bone interface should be monitored. 
     The second rod and its respective set screws are placed according to the techniques previously outlined. Following placement of the second rod and set screws, convex compressive forces are placed on the segments using a parallel compressor to horizontalize the lowest instrumented vertebra and mildly compress the convexity of the deformity. It is preferred that compression be released just prior to final tightening. This technique helps ensure that the implant head and rod are normalized to one another and allows for the rod to be fully seated in the implant head during the final tightening step. 
     With all rods and screw placed and provisionally secured with set screws, the set screws are tightened to their final torque. The counter torque wrench and the set screw driver  850  are placed onto the open screw, saddle, and set screw. A torque limiting T-handle is placed on the set screw driver  850  and turned clockwise while firmly holding the counter torque wrench. The torque liming T-handle is preferably set to 70 in-lbs. The T-handle is turned clockwise until an audible click is heard indicating the proper torque has been met. 
     After final tightening of the set screws, cross connectors are placed. The cross connector connection provides rotational stability to the construct as a framed construct resists rotational forces. The cross connectors should be placed close to the construct extremities but placement at other positions along the construct is also envisioned. 
     Bi-axial cross connectors  330  are affixed to the spinal rods  112 ,  114  by capturing a rod in each of the cross connector rod hooks  322  at the end of each linkage  334 ,  336 . Prior to attaching the bi-axial cross connector  330  to the spinal rods  112 ,  114  the midline nut  338  or midline locking screw  339  is provisionally tightened. A first rod is captured in the cross connector rod hook  322  at the end of one of the linkages  334 ,  336  and the conical screw  302  is provisionally tightened to anchor the device to the rod. The midline nut  338  or midline locking screw  339  is loosened to allow the linkages  334 ,  336  to angulated and lengthen or shorten. A second rod is captured in the cross connector rod hook  322  at the end of the other linkage  334 ,  336  and the conical screw  302  is provisionally tightened. The midline nut  338  or midline locking screw  339  is re-tightened to secure the linkages  334 ,  336  of the bi-axial cross connector  330 . For final tightening of the conical screw  302 , the counter torque tube and screw driver are placed onto the bi-axial cross connector  330 , spinal rod  112 ,  114 , and conical screw. A torque limiting T-handle is placed on the driver shaft and turned clockwise while firmly holding the counter torque wrench. The torque liming T-handle is preferably set to 50 in-lbs. The T-handle is turned clockwise until an audible click is heard indicating the proper torque has been met. 
     Fixed cross connectors  300  are affixed to the spinal rods  112 ,  114  by placing the fixed cross connector over the rods such that a rod is seated in each cross connector rod hook  322 . The conical screws  302  are provisionally tightened and then finally tightened using a counter torque tube, driver shaft, and torque limiting T-handle as with the bi-axial cross connectors  330 . For some applications, the fixed cross connector extension rod  304  of the fixed cross connector  300  may need to be bent to fit the anatomy and spinal rod  112 ,  114  arrangement. 
     For a hook  210 ,  220  based correction technique, the surgical site is prepared by dividing the facet capsule. A portion of the inferior facet process may also be removed to facilitate insertion of the hook  210 ,  220 . The pedicle should be clearly identified with the help of a pedicle elevator. The pedicle hook may be inserted from T1 to T10 with the hook blade  212  cephalad and in the infralaminar position. The hook blade  212  of the hook  210 ,  220  should wrap around the pedicle and not split the inferior articular process. To assist in position the pedicle hook, a hook pusher may be utilized. 
     For hook placement at the transverse process a wide blade hook is typically used in a pedicle-transverse claw construct as a caudal hook. Laminar hook trials may be used to separate the ligamentous attachment between the undersurface of the transverse process and the posterior arch of the rib medial to the rib-transverse joint. The hook is then inserted using a hook holder. 
     For placement of thoracic hooks a partial or total division of the spinous process directly above the vertebra to be instrumented may be performed. A division and/or partial removal of the ligamentum flavum and a small laminotomy are carried out on the superior lamina. The amount of bone removed from the lamina may vary depending on the size of the hook blade  212  and throat angle chosen. The upper edge of the lamina below or the lower edge of the lamina above may be resected to ease placement of the hook  210 ,  220 . A laminar hook trial may also be used to check the space between laminar and peridural structures. When placing a hook  210 ,  220  on the superior lamina a hook should be used to insert the hook. 
     With all the appropriate hooks placed on the side of the deformity to be corrected, a rod template is used to measure the length and curve. The spinal rod  112 ,  114  on the corrective side should be cut 2-3 cm longer than the actual length to leave adequate length for correction. The spinal rod  112 ,  114  is then bent into the correct orientation using a french bender or tubular benders. 
     Any hooks  210 ,  220  which are not stable prior to spinal rod  112 ,  114  insertion should be removed until placement of the rod. 
     The spinal rod  112 ,  114  and set screws  120  are placed and provisionally tightened according to the same technique outlined for pedicle screws. Rotation, in-situ bending, compression, and distraction maneuvers may be completed undertaken. During rod rotation it is important to monitor the interval hooks as they tend to back out. 
     Upon completion of the deformity correction and the seating of the correction rod, the opposite side of the construct is prepared. Using a french bender, the rod for the opposite side of the construct is contoured according to the curvature of the spine and the residual position of alignment from the correction rod. The contoured rod is placed into the hooks  210 ,  220  with the rod holder or by hand and provisionally secured with set screws  120 . With the spinal rod  112 ,  114  secured to the implants, distraction and/or compression is performed to place the hooks  210 ,  220  into their final position. The set screws  120  are subsequently finally tightened according to the technique previously discussed for pedicle screws and cross connectors  300 ,  330 . 
     Cross connectors  300 ,  330  are preferably also added to the construct for added rotational stability. 
     This is simply an exemplary surgical technique and other known and accepted methods or techniques for performing steps outlined within the technique may be substituted where appropriate. 
     The previous text sets forth a broad description of numerous different embodiments. The description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible, and it will be understood that any feature, characteristic, component, step or methodology described herein can be deleted, combined with or substituted for, in whole or part, any other feature, characteristic, component, step or methodology described herein. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims. 
     It should also be understood that, unless a term is expressly defined in this specification using the sentence “As used herein, the term ‘ —————— ’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). No term is intended to be essential unless so stated. To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such a claim term be limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. §112, sixth paragraph or similar doctrine. 
     It is also noted that recitations herein of “at least one” component, element, etc., should not be used to create an inference that the alternative use of the articles “a” or “an” should be limited to a single component, element, etc. 
     It is noted that recitations herein of a component of the present disclosure being “configured” to embody a particular property, or function in a particular manner, are structural recitations, as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “configured” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component. 
     It is noted that terms like “preferably,” “commonly,” and “typically,” when utilized herein, are not utilized to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to identify particular aspects of an embodiment of the present disclosure or to emphasize alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure. 
     For the purposes of describing and defining the present invention it is noted that the terms “substantially” and “approximately” are utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms “substantially” and “approximately” are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. 
     Having described the subject matter of the present disclosure in detail and by reference to specific embodiments thereof, it is noted that the various details disclosed herein should not be taken to imply that these details relate to elements that are essential components of the various embodiments described herein, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Rather, the claims appended hereto should be taken as the sole representation of the breadth of the present disclosure and the corresponding scope of the various inventions described herein. Further, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects. 
     The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.” 
     Every document cited herein, including any cross referenced or related patent or application is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made. It is therefore intended to cover in the appended claims all such changes and modifications.