Abstract:
A telescopic insertion assembly is configured to insert a pedicle screw into a vertebral body. The insertion assembly includes an attachment fixture having one end configured to mate with the pedicle screw and another end having a ridged portion. A center tube is provided having one end slidably attached to the attachment fixture and another end having an internally ridged portion. A telescoping member has one ridged end configured to slidably attach to the center tube and another end having a yoke. The telescoping member is configured to extend the yoke to different distances from the center tube. An alignment member is configured to hingeably attach to the yoke of the telescoping member. The alignment member is configured to rotate from a first position to a second position. The second position of the alignment member is above a top surface of a patient&#39;s skin.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 61/061,568 filed Jun. 13, 2008, the disclosure of which is incorporated herein by reference. 
     
    
     STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT AND CROSS-RELATED APPLICATIONS 
       [0002]    This invention was not made with any government support. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    This invention relates to the field of orthopedic surgery and more particularly to the area of spinal surgery. Spinal surgery can involve the insertion of pedicle screws into adjacent vertebral bodies. Minimally invasive surgery involves the use of small incisions. The use of small incisions provides for reduced muscle damage, decreased blood loss, less postoperative pain, reduced scarring, shorter inpatient hospital stay, and improved operative results. During minimally invasive surgery, pedicle screws can be inserted through small incisions using imaging or navigational guidance. Small incisions in the patient&#39;s skin can be made precisely over the desired location, and pedicle screws can be inserted utilizing extended tube assemblies. Once all of the desired screws have been inserted, a longitudinal member, such as for example a rod, can be inserted in a percutaneous manner and secured to the pedicle screws with desired retainers. 
         [0004]    However, it can be difficult to maneuver the extended screw assemblies in the event that multiple pedicles screws are being inserted. Additionally, lumbar lordosis can produce crowding in the surgical area, which can result in difficulty in aligning the extended tube assemblies. Thus, there is a need for an improved insertion assembly for placement of pedicle screws that overcomes aforementioned drawbacks of previously described insertion tube assemblies. 
       SUMMARY OF THE INVENTION 
       [0005]    According to this invention, there is provided a telescopic insertion assembly configured to insert a pedicle screw into a vertebral body. The insertion assembly includes an attachment fixture having one end configured to mate with the pedicle screw and another end having a ridged portion. A center tube is provided having one end slidably attached to the attachment fixture and another end having an internally ridged portion. A telescoping member has one ridged end configured to slidably attach to the center tube and another end having a yoke. The telescoping member is configured to extend the yoke to different distances from the center tube. An alignment member is configured to hingeably attach to the yoke of the telescoping member. The alignment member is configured to rotate from a first position to a second position. The second position of the alignment member is above a top surface of a patient&#39;s skin. 
         [0006]    According to this invention, there is also provided a telescopic insertion assembly configured to insert a pedicle screw into a vertebral body. The telescopic insertion assembly includes an attachment fixture having one end configured to mate with the pedicle screw and another end having a ridged portion. A center tube has one end slidably attached to the attachment fixture and another end has an internal portion. A telescoping member has one end slidably attached to the center tube and another end has a collar. The collar includes a plurality of apertures. The telescoping member is configured to extend the collar to different distances from the center tube. An alignment tool has a plurality of prongs configured to engage the plurality of apertures in the collar. The alignment tool maintains the collar of the telescoping member at a level above a top surface of a patient&#39;s skin. 
         [0007]    According to this invention, there is also provided a reducing retainer configured for retaining a longitudinal member in a head of a pedicle screw. The reducing retainer includes a retainer portion configured to attach to the head of the pedicle screw and retain a longitudinal member in the head. An extension section is connected to the retainer portion. The extension section has a weakened area. A head portion is connected to the extension section and has a drive structure. Rotational movement applied to the drive structure is configured to seat the longitudinal member in the head of the pedicle screw. Further rotational movement of the drive structure is configured to break the weakened area of the extension section. The extension section and the drive structure can be removed after the weakened area is broken. 
         [0008]    According to this invention, there is also provided an assembly configured for centralizing of a longitudinal member within a plurality of telescopic insertion assemblies. The assembly includes a rod holder having a handle and an extension member. The handle has an aperture. The extension member has an aperture. The aperture of the extension member is configured for placement over an extension of a longitudinal member. A centralizer has a handle and an elongated member. The elongated member is configured for insertion through the aperture in the handle of the rod holder. The elongated member is further configured to substantially encircle the extension member. The centralizer centralizes the longitudinal member among the plurality of telescopic insertion assemblies. 
         [0009]    According to this invention, there is also provided a center tube for use in a telescopic insertion assembly. The center tube includes a lower end configured for releasable attachment to a pedicle screw, a middle portion connected to the lower end and an upper end connected to the middle portion. A pivotable section is pivotably attached to the middle portion and extends into the upper end. The pivotable section is configured to pivot from a first closed position to a second open position. In the second open position, a passage is formed between the pivotable section and the center tube. The passage is configured to provide access to position a longitudinal member within the telescopic insertion assembly. 
         [0010]    According to this invention, there is also provided an insertion assembly for penetrating vertebral bodies. The insertion assembly includes a cannula having an inner passage, an obturator configured for substantial housing within the passage of the cannula and a depth stop attached to the cannula. The depth stop is configured as a marker to indicate the insertion depth of the insertion device. 
         [0011]    Various objects and advantages will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of a first embodiment of a vertebra penetration device in accordance with this invention. 
           [0013]      FIG. 2  is a cross-sectional view of a portion of the first embodiment of the penetration device illustrated in  FIG. 1 . 
           [0014]      FIG. 3  is a cross-sectional view of a portion of a second embodiment of the penetration device illustrated in  FIG. 1 . 
           [0015]      FIG. 4  is a cross-sectional view of a portion of a third embodiment of the penetration device illustrated in  FIG. 1 . 
           [0016]      FIG. 5  is an exploded perspective view of a first embodiment of a vertebra screw insertion assembly in accordance with this invention. 
           [0017]      FIG. 6  is an exploded perspective view of a second embodiment of a vertebra screw insertion assembly in accordance with this invention. 
           [0018]      FIG. 7  is a perspective view of a plurality of vertebra screw insertion assemblies shown in an initial orientation. 
           [0019]      FIG. 8  is a perspective view of the plurality of vertebra screw insertion assemblies illustrated in  FIG. 7  shown in an aligned orientation. 
           [0020]      FIG. 9  is a perspective view of the plurality of vertebra screw insertion assemblies illustrated in  FIG. 8  shown in an aligned and locked orientation. 
           [0021]      FIG. 10  is a perspective view of the plurality of vertebra screw insertion assemblies illustrated in  FIG. 9  having an alignment rod installed therein. 
           [0022]      FIG. 11  is a perspective view in cross section of a portion of one of the plurality of the vertebra screw insertion assemblies illustrated in  FIG. 10  together with a rod holder for initially positioning the alignment rod relative to the vertebra insertion assemblies. 
           [0023]      FIG. 12  is a sectional elevational view taken along line  12 - 12  of  FIG. 11 . 
           [0024]      FIG. 13  is a perspective view similar to  FIG. 11  of a portion of one of the plurality of the vertebra screw insertion assemblies, the rod holder, and a centralizer for finally positioning the alignment rod relative to the vertebra screw insertion assemblies. 
           [0025]      FIG. 14  is a sectional elevational view taken along line  14 - 14  of  FIG. 13 . 
           [0026]      FIG. 15  is an enlarged perspective view of portions of the portion of one of the vertebra screw insertion assemblies, the rod holder, and the centralizer illustrated in  FIGS. 13 and 14 . 
           [0027]      FIG. 16  is a perspective view of the plurality of the vertebra screw insertion assemblies, with the rod holder and the centralizer removed and with a plurality of retainers therein. 
           [0028]      FIG. 17  is a perspective view of a first embodiment of the alignment rod illustrated in  FIGS. 1 through 16 . 
           [0029]      FIG. 18  is a perspective view of a second embodiment of the alignment rod illustrated in  FIGS. 1 through 16 . 
           [0030]      FIG. 19  is a perspective view of a second embodiment of an intermediate tube shown in a closed position. 
           [0031]      FIG. 20  is a perspective view of the intermediate tube illustrated in  FIG. 19  shown in an opened position. 
           [0032]      FIG. 21  is a perspective view of a third embodiment of an intermediate tube shown in an opened position. 
           [0033]      FIG. 22  is an exploded perspective view of a second embodiment of a vertebra screw insertion assembly in accordance with this invention. 
           [0034]      FIG. 23  is schematic sectional elevational view of portions of the first vertebra screw insertion assembly  10  illustrated in  FIG. 5 . 
           [0035]      FIG. 24  is schematic sectional elevational view similar to  FIG. 23  of an alternative arrangement of portions of the first vertebra screw insertion assembly  10  illustrated in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    Referring now to the drawings, there is illustrated in  FIG. 1  a first embodiment of a vertebra penetration device, indicated generally at  1 , in accordance with this invention. The vertebra penetration device  1  is adapted to penetrate a vertebral body for a purpose that will be explained below. For example, the vertebra penetration device  1  can penetrate a vertebral body to form a bone tunnel for use in a surgical procedure. The illustrated vertebra penetration device  1  is a Jamshidi needle. However, the vertebra penetration device  1  can be embodied as any other structure. 
         [0037]    The illustrated vertebra penetration device  1  includes a cannula  2 , an obturator  3  that is slidably disposed within the cannula  2 , and a handle  4 . The handle  4  may include a removable portion  4   a , although such is not required. The removable portion  4   a  of the handle  4  may be connected to the obturator  3  such that removal of the removable portion  4   a  causes removal of the obturator  3  from the cannula  2 . 
         [0038]    Referring now to  FIG. 2 , a portion of the vertebra penetration device  1  is illustrated in detail. As shown therein, the illustrated cannula  2  is generally hollow and cylindrical in shape. However, the cannula  2  can have any other desired shape or combination of shapes. The obturator  3  extends through interior of the cannula  2  and is supported for sliding movement relative thereto in any conventional manner. The outer surface of the cannula  2  has a depth indicator  5  provided therein. The depth indicator  5  can be embodied as any structure that can function as a marker to indicate the insertion depth of the cannula  2  within a vertebra during a surgical procedure. During such a surgical procedure, conventional imaging techniques, such as X-rays and the like, can be used to determine the location of the depth indicator  5  relative to the vertebra, thereby clearly indicating how far the cannula  2  has been inserted in the vertebra. The depth indicator  5  can be positioned at any desired predetermined distance from an end of the cannula  2  for this purpose. 
         [0039]    In the illustrated embodiment, the depth indicator  5  has a generally rectangular cross sectional shape, having side walls that extend generally perpendicularly outwardly relative to the outer surface of the cannula  2  and an outer surface that extends generally concentrically relative to the outer surface of the cannula  2 . However, the depth indicator  5  may be formed having any desired cross sectional shape or size that protrudes outwardly from the outer surface of the cannula  2 . In the illustrated embodiment, the depth indicator  5  extends continuously about the outer surface of the cannula  2 . However, the depth indicator  5  can be formed as one or more segments that extend about the outer surface of the cannula  2  in a non-continuous manner. The illustrated depth indicator  5  may be formed integrally with the remainder of the cannula  2  or may be formed from a separate piece that is secured thereto. 
         [0040]      FIG. 3  illustrates a portion of a second embodiment of a vertebra penetration device, indicated generally at  1 ′. This second embodiment of the vertebra penetration device  1 ′ includes a modified cannula  6  that supports the obturator  3  for sliding movement therein. The cannula  6  has first and second dimensional portions that define a modified depth indicator  7  therebetween. The first and second dimensional portions of the cannula  6  can have any desired shapes or sizes that define the depth indicator  7 . Similarly, the depth indicator  7  can have any desired shape or combination of shapes. The depth indicator  7  functions in the same manner as described above in connection with the depth indicator  5  to clearly indicate how far the cannula  2  has been inserted in the vertebra during a surgical procedure. 
         [0041]      FIG. 4  illustrates a portion of a third embodiment of a vertebra penetration device, indicated generally at  1 ″. This third embodiment of the vertebra penetration device  1 ″ includes a modified cannula  8  that supports the obturator  3  for sliding movement therein. The outer surface of the cannula  8  has a depth indicator  9  provided therein. In the illustrated embodiment, the depth indicator  9  has a generally triangular cross sectional shape, having side walls that extend inwardly at an non-perpendicular angle relative to the outer surface of the cannula  8 . However, the depth indicator  9  may be formed having any desired cross sectional shape or size that extends inwardly from the outer surface of the cannula  8 . The depth indicator  9  functions in the same manner as described above in connection with the depth indicator  5  to clearly indicate how far the cannula  2  has been inserted in the vertebra during a surgical procedure. 
         [0042]    Referring now to  FIG. 5 , there is illustrated a first embodiment of a vertebra screw insertion assembly  10  in accordance with this invention. The vertebra screw insertion assembly  10  is adapted to facilitate the securement of a pedicle screw  12  in a hole formed in a vertebra during a spinal surgical procedure (the hole being initially formed by the vertebra penetration device  1  described above). As will be explained in detail below, the axial length of the vertebra screw insertion assembly  10  is adjustable to facilitate its use with patients of differing sizes and shapes. 
         [0043]    The pedicle screw  12  is conventional in the art and is adapted to be inserted into a vertebra (not shown) in any known manner. The illustrated pedicle screw  12  includes a threaded portion  13  and a head portion  14 . The threaded portion  13  is configured for insertion into the vertebra and can have any desired root diameter, thread diameter, pitch, and number of threads. The head portion  14  includes a generally U-shaped yoke  15 , a retainer structure  16 , a pair of generally V-shaped drive slots  17 , and an internally threaded portion  18  (for purposes of clarity, the threads of the internally threaded portion  18  are not shown). The pedicle screw  12  can be formed from any desired material. 
         [0044]    The vertebra screw insertion assembly  10  also includes a lower portion indicated generally at  20 . The lower portion  20  is generally hollow and cylindrical in shape, although such is not required. The lower portion  20  has an upper end  21  having a plurality of drive structures  22  provided therein. In the illustrated embodiment, the drive structures  22  are embodied as a plurality of slots extending downwardly from the upper end  21  of the lower portion  20 . However, the drive structures  22  may be embodied as any desired structure. The purpose for the drive structures  22  will be explained below. In the illustrated embodiment, the outer surface of the upper end  21  of the lower portion  20  is formed having a plurality of axial retaining structures  23 . The illustrated axial retaining structures  23  are a series of concentric annular protrusions. However, the axial retaining structures  23  may be embodied as any desired structure or series of structures. Alternatively, the axial retaining structures  23  may be omitted and a smooth outer surface be provided if desired. 
         [0045]    The lower portion  20  also has an outwardly extending protrusion  24  provided therein. In the illustrated embodiment, the outwardly extending protrusion  24  is embodied as a hollow cylindrical protrusion. However, the outwardly extending protrusion  24  may be embodied as any desired structure. Alternatively, the outwardly extending protrusion  24  may be omitted if desired. The purpose for the outwardly extending protrusion  24  will be explained below. 
         [0046]    The lower portion  20  further has a lower end  25  having a plurality of drive structures  26  provided therein. In the illustrated embodiment, the drive structures  26  are embodied as a plurality of generally V-shaped extensions extending downwardly from the lower end  25  of the lower portion  20 . However, the drive structures  26  may be embodied as any desired structure. The purpose for the drive structures  26  will be explained below. Lastly, the lower portion  20  of the vertebra screw insertion assembly  10  has a slot  27  extending axially throughout the length thereof. The purpose for the slot  27  will be explained below. 
         [0047]    The vertebra screw insertion assembly  10  also includes an intermediate portion indicated generally at  30 . The intermediate portion  30  is generally hollow and cylindrical in shape, although such is not required. The intermediate portion  30  has an upper end  31  and a lower end  32 . In the illustrated embodiment, the inner surface of the upper end  31  of the intermediate portion  30  is formed having a plurality of axial retaining structures  33 . The illustrated axial retaining structures  33  are a series of concentric annular protrusions. However, the axial retaining structures  33  may be embodied as any desired structure or series of structures. Alternatively, the axial retaining structures  33  may be omitted and a smooth inner surface be provided if desired. 
         [0048]    The intermediate portion  30  also has a slot  34  provided therein. In the illustrated embodiment, the slot  34  is elongated and extends generally axially. However, the slot  34  may have any desired shape. Alternatively, the slot  34  may be omitted if desired. The purpose for the slot  34  will be explained below. 
         [0049]    The lower end  32  of the intermediate portion  30  has a retaining structure  35  provided therein. In the illustrated embodiment, the retaining structure  35  is embodied as a lip that extends inwardly about the lower end  32  of the intermediate portion  30 . However, the retaining structure  35  may be embodied as any desired structure. The purpose for the retaining structure  35  will be explained below. Lastly, the intermediate portion  30  of the vertebra screw insertion assembly  10  has a slot  36  extending axially throughout the length thereof. The purpose for the slot  36  will be explained below. 
         [0050]    The vertebra screw insertion assembly  10  also includes an upper portion indicated generally at  40 . The upper portion  40  is generally hollow and cylindrical in shape, although such is not required. The upper portion  40  has an upper end  41  having a plurality of arms  42  provided therein. Each of the arms  42  has an opening  42   a  formed therethrough, although such is not required. The arms  42  may be embodied as any desired structure. The purpose for the arms  42  will be explained below. The upper portion  40  further has a lower end  43 . In the illustrated embodiment, the outer surface of the lower end  43  of the upper portion  40  is formed having a plurality of axial retaining structures  44 . The illustrated axial retaining structures  44  are a series of concentric annular protrusions. However, the axial retaining structures  44  may be embodied as any desired structure or series of structures. Alternatively, the axial retaining structures  44  may be omitted and a smooth outer surface be provided if desired. Lastly, the upper portion  40  of the vertebra screw insertion assembly  10  has a slot  45  extending axially throughout the length thereof. The purpose for the slot  45  will be explained below. 
         [0051]    Lastly, the vertebra screw insertion assembly  10  includes an alignment bracket, indicated generally at  46 . The illustrated alignment bracket  46  includes a pair of bracket arms  47  that are connected together by an transverse bar  48 . Each of the bracket arms  47  has an inwardly extending protrusion  49  (only one is illustrated) provided thereon. However, the alignment bracket  46  may have any desired shape. The purpose for the alignment bracket  46  will be explained below. 
         [0052]    Referring now to  FIG. 6 , there is illustrated a second embodiment of a vertebra screw insertion assembly  10 ′ in accordance with this invention. The second embodiment of a vertebra screw insertion assembly  10 ′ is similar to the first embodiment  10  described above, and like reference numbers are used to identify similar structures. As will be explained in detail below, the axial length of the vertebra screw insertion assembly  10 ′ is also adjustable to facilitate its use with patients of differing sizes and shapes. 
         [0053]    The vertebra screw insertion assembly  10 ′ includes a lower portion indicated generally at  20 ′. The lower portion  20 ′ is generally hollow and cylindrical in shape, although such is not required. The lower portion  20 ′ has an upper end  21 ′ having a plurality of drive structures  22 ′ provided therein. In the illustrated embodiment, the drive structures  22 ′ are embodied as a plurality of slots extending downwardly from the upper end  21 ′ of the lower portion  20 ′. However, the drive structures  22 ′ may be embodied as any desired structure. The purpose for the drive structures  22 ′ will be explained below. In the illustrated embodiment, the outer surface of the upper end  21 ′ of the lower portion  20 ′ is formed having a plurality of axial retaining structures  23 ′. The illustrated axial retaining structures  23 ′ are a series of concentric annular protrusions. However, the axial retaining structures  23 ′ may be embodied as any desired structure or series of structures. Alternatively, the axial retaining structures  23 ′ may be omitted and a smooth outer surface be provided if desired. 
         [0054]    The lower portion  20 ′ also has an outwardly extending protrusion  24 ′ provided therein. In the illustrated embodiment, the outwardly extending protrusion  24 ′ is embodied as a hollow cylindrical protrusion. However, the outwardly extending protrusion  24 ′ may be embodied as any desired structure. Alternatively, the outwardly extending protrusion  24 ′ may be omitted if desired. The purpose for the outwardly extending protrusion  24 ′ will be explained below. 
         [0055]    The lower portion  20 ′ further has a lower end  25 ′ having a plurality of drive structures  26 ′ provided therein. In the illustrated embodiment, the drive structures  26 ′ are embodied as a plurality of generally V-shaped extensions extending downwardly from the lower end  25 ′ of the lower portion  20 ′. However, the drive structures  26 ′ may be embodied as any desired structure. The purpose for the drive structures  26 ′ will be explained below. Lastly, the lower portion  20 ′ of the vertebra screw insertion assembly  10 ′ has a slot  27 ′ extending axially throughout only a portion of the length thereof. The purpose for the slot  27 ′ will be explained below. 
         [0056]    The vertebra screw insertion assembly  10 ′ also includes an intermediate portion indicated generally at  30 ′. The intermediate portion  30 ′ is generally hollow and cylindrical in shape, although such is not required. The intermediate portion  30 ′ has an upper end  31 ′ and a lower end  32 ′. In the illustrated embodiment, the inner surface of the upper end  31 ′ of the intermediate portion  30 ′ is formed having a plurality of axial retaining structures  33 ′. The illustrated axial retaining structures  33 ′ are a series of concentric annular protrusions. However, the axial retaining structures  33 ′ may be embodied as any desired structure or series of structures. Alternatively, the axial retaining structures  33 ′ may be omitted and a smooth inner surface be provided if desired. 
         [0057]    The intermediate portion  30 ′ also has a slot  34 ′ provided therein. In the illustrated embodiment, the slot  34 ′ is elongated and extends generally axially. However, the slot  34 ′ may have any desired shape. Alternatively, the slot  34 ′ may be omitted if desired. The purpose for the slot  34 ′ will be explained below. 
         [0058]    The lower end  32 ′ of the intermediate portion  30 ′ has a retaining structure  35 ′ provided therein. In the illustrated embodiment, the retaining structure  35 ′ is embodied as a lip that extends inwardly about the lower end  32 ′ of the intermediate portion  30 ′. However, the retaining structure  35 ′ may be embodied as any desired structure. The purpose for the retaining structure  35 ′ will be explained below. Lastly, the intermediate portion  30 ′ of the vertebra screw insertion assembly  10  has a slot  36 ′ extending axially throughout only a portion the length thereof. The purpose for the slot  36 ′ will be explained below. 
         [0059]    The vertebra screw insertion assembly  10 ′ also includes an upper portion indicated generally at  40 ′. The upper portion  40 ′ is generally hollow and cylindrical in shape, although such is not required. The upper portion  40 ′ has an upper end  41 ′ having a plurality of arms  42 ′ provided therein. Each of the arms  42 ′ has an opening  42   a ′ formed therethrough, although such is not required. The arms  42 ′ may be embodied as any desired structure. The purpose for the arms  42 ′ will be explained below. The upper portion  40 ′ further has a lower end  43 ′. In the illustrated embodiment, the outer surface of the lower end  43 ′ of the upper portion  40 ′ is formed having a plurality of axial retaining structures  44 ′. The illustrated axial retaining structures  44 ′ are a series of concentric annular protrusions. However, the axial retaining structures  44 ′ may be embodied as any desired structure or series of structures. Alternatively, the axial retaining structures  44 ′ may be omitted and a smooth outer surface be provided if desired. 
         [0060]    Lastly, the vertebra screw insertion assembly  10 ′ includes an alignment bracket, indicated generally at  46 . The illustrated alignment bracket  46  is the same as described above in connection with the vertebra screw insertion assembly  10 . The purpose for the alignment bracket  46  will be explained below. 
         [0061]      FIG. 7  shows the first embodiment of the vertebra screw insertion assembly  10  in an initial orientation. As shown therein, the lower portion  20  of the vertebra screw insertion assembly  10  is disposed within the intermediate portion  30  thereof such that the protrusion  24  is received within the slot  34 . The retaining structure  16  of the pedicle screw  12  engages the retaining lip  35  provided on the intermediate portion  30  of the vertebra screw insertion assembly  10 , and the generally V-shaped extensions  26  provided on the lower end  25  of the lower portion  20  are received within the generally V-shaped drive slots  17  of the pedicle screw  12 . Thus, in a manner that is known in the art, rotation of the lower portion  20  of the vertebra screw insertion assembly  10  (which can be accomplished by means of a conventional tool (not shown) that engages the drive slots  22 ) causes rotation of the pedicle screw  12 . Accordingly, the pedicle screw  12  can be threaded into a bone tunnel, such as might be formed by the vertebra penetration device  1  described above. The retaining bracket  46  is pivotably connected to the upper end  42  of the upper portion  40  of the vertebra screw insertion assembly  10 . This can be accomplished by inserting the inwardly extending protrusions  49  provided on the bracket arms  47  into the openings  42   a  provided on the arms  42  of the upper end  41  of the upper portion  40 . 
         [0062]    The axial length of the vertebra screw insertion assembly  10  is adjustable to facilitate its use with patients of differing sizes and shapes. This is done so that a minimum amount of the vertebra screw insertion assembly  10  will extend outwardly from the patient, thereby providing a maximum amount of clearance in the surgical field above the skin of the patient. As discussed above, the lower end  43  of the upper portion  40  of the vertebra screw insertion assembly  10  is received axially within the upper end  31  of the intermediate portion  30  thereof. The upper portion  40  of the vertebra screw insertion assembly  10  can thus be axially positioned relative to the intermediate portion  30  thereof by moving the upper portion  40  to a desired position relative to the intermediate portion  30 . This can be accomplished manually, by means of a tool (not shown), or any other means. When so positioned, the upper portion  40  of the vertebra screw insertion assembly  10  is located in a desired axial position relative to the intermediate portion  30  thereof based upon the size and shape of the patient. 
         [0063]    In order to retain the upper portion  40  of the vertebra screw insertion assembly  10  in the desired axial position relative to the intermediate portion  30  thereof, the illustrated plurality of axial retaining structures  44  provided on the outer surface of the lower end  43  of the upper portion  40  engages the corresponding plurality of axial retaining structures  33  provided on the inner surface of the upper end  31  of the intermediate portion  30 . In this manner, a desired axial length of the vertebra screw insertion assembly  10  can be achieved and retained for further use, as described below. As mentioned above, however, the axial retaining structures  33  and  44  may be embodied as any other desired structure or series of structures. Alternatively, the axial retaining structures  33  and  44  may be omitted and smooth surfaces can be provided if desired. All that is necessary is that the axial length of the vertebra screw insertion assembly  10  be adjustable to facilitate its use with patients of differing sizes and shapes. 
         [0064]      FIG. 7  also shows two of the second embodiment of the vertebra screw insertion assemblies  10 ′ in an initial orientation. The arrangement of the various elements of the second embodiment of the vertebra screw insertion assemblies  10 ′ is the same as described above in connection with the first embodiment of the vertebra screw insertion assembly  10 . In the same manner as described above, and for the same reason, the axial lengths of the vertebra screw insertion assemblies  10  are adjustable to facilitate their use with patients of differing sizes and shapes. 
         [0065]    As shown in  FIG. 7 , the slot  27  formed through the lower portion  20  of the vertebra screw insertion assembly  10 , the slot  36  formed through the intermediate portion  30  of the vertebra screw insertion assembly  10 , and the slot  45  formed through the upper portion  40  of the vertebra screw insertion assembly  10  are all axially aligned with one another to provide a continuous slot through the vertebra screw insertion assembly  10 . As also shown in  FIG. 7 , this continuous slot through the vertebra screw insertion assembly  10  is oriented facing inwardly toward the adjacent one of the plurality of vertebra screw insertion assemblies  10 ′. The purpose for this continuous slot and the reason for its orientation in this manner will be described below. 
         [0066]      FIG. 8  shows the plurality of vertebra screw insertion assemblies  10  and  10 ′ illustrated in  FIG. 7  shown in an aligned orientation. This is accomplished by pivoting each of the alignment brackets  46  from the unaligned positions illustrated in  FIG. 7  into the aligned positions illustrated in  FIG. 8 . In such aligned positions, the alignment bracket  46  provided on the vertebra screw insertion assembly  10  engages the alignment bracket  46  provided on the adjacent first vertebra screw insertion assembly  10 . Similarly, the alignment bracket  46  provided on the first vertebra screw insertion assembly  10 ′ engages the alignment bracket  46  provided on the adjacent second vertebra screw insertion assembly  10 ′. Any number of such vertebra screw insertion assemblies  10  and  10 ′ may be aligned in this manner. In the illustrated embodiment, the alignment brackets  46  engage each other in a nested manner, although such is not required. 
         [0067]      FIG. 9  is a perspective view of the plurality of vertebra screw insertion assemblies illustrated in  FIG. 8  shown in an aligned and locked orientation. To accomplish this, a locking bracket  50  is engaged with some or all of the alignment brackets  46  provided on the first and second vertebra screw insertion assemblies  10  and  10 ′. The locking bracket  50  is optional and may be embodied as any desired structure that is capable of engaging some or all of the alignment brackets  46  and for positively maintaining them in desired positions relative to one another. Preferably, the locking bracket  50  has at least one opening  51  formed therethrough (two are shown in the illustrated embodiment) for a purpose that will be explained below. When the locking bracket  50  is installed as shown in  FIG. 9 , the outer ends of the first and second vertebra screw insertion assemblies  10  and  10 ′ are generally locked in alignment with one another. 
         [0068]    Next, as shown in  FIG. 10 , an alignment rod  55  is installed in the first and second vertebra screw insertion assemblies  10  and  10 ′. The illustrated alignment rod  55  includes a body portion  56  having a positioning post  57  extending therefrom. The structure of the alignment rod  55  will be explained in greater detail below. The alignment rod  55  can be installed in the first and second vertebra screw insertion assemblies  10  and  10 ′ along a path defined by the dotted line A in  FIG. 10 . As mentioned above, the slot  27  formed through the lower portion  20  of the vertebra screw insertion assembly  10 , the slot  36  formed through the intermediate portion  30  of the vertebra screw insertion assembly  10 , and the slot  45  formed through the upper portion  40  of the first vertebra screw insertion assembly  10  are all axially aligned with one another to provide a continuous slot through the first vertebra screw insertion assembly  10 . The path defined by the dotted line A in  FIG. 10  extends through this continuous slot. During insertion, portions of the alignment rod  55  pass through portions of the interior of the first vertebra screw insertion assembly  10 . The continuous slot thus provides sufficient clearance for the alignment rod  55  to be installed in the first and second vertebra screw insertion assemblies  10  and  10 ′. When so installed, the body portion  56  of the alignment rod  55  is generally received within the generally U-shaped yokes  15  of the pedicle screws  12 , and the positioning post  57  is generally received within the interior of the first vertebra screw insertion assembly  10 . 
         [0069]    After being installed, it is desirable to precisely position the alignment rod  55  relative to the first vertebra screw insertion assembly  10 . This can be accomplished by means of a first positioning tool, indicated generally at  60  in  FIG. 11 . As shown therein, the first positioning tool  60  includes a handle  61  having a hollow interior  61   a  and an elongated shaft  62  that extends from the handle  61 . A generally C-shaped slot  63  is formed through the handle  61  adjacent to the shaft  62 . The lower end of the shaft  62  has a counterbore  64  formed therein. The first positioning tool  60  can be installed by inserting the shaft  63  downwardly through the first vertebra screw insertion assembly  10  such that the positioning post  57  of the alignment rod  55  is received within the counterbore  64 . As best shown in  FIG. 12 , the positioning post  57  of the alignment rod  55  is preferably received snugly within the counterbore  64  of the first positioning tool  60  such that the alignment rod  55  and the first positioning tool  60  are precisely positioned relative to one another. Also, the positioning post  57  of the alignment rod  55  and the counterbore  64  of the first positioning tool  60  are formed having non-circular cross sectional shapes for a purpose that will be explained below. 
         [0070]    After the first positioning tool  60  has been installed, a second positioning tool, indicated generally at  65  in  FIG. 13 , is also installed. As shown therein, the second positioning tool  65  includes a handle  66  having an elongated generally C-shaped shaft  67  that extends therefrom. The generally C-shaped shaft  67  is sized and shaped so as to extend through the generally C-shaped slot  63  formed through the handle  61  and about the shaft  62  of the first positioning tool  60 . As best shown in  FIGS. 14 and 15 , the generally C-shaped shaft  67  of the second positioning tool  65  is preferably received snugly between outer surface of the shaft  62  of the first positioning tool  60  and the inner surface of the lower member  20  of the first vertebra screw insertion assembly  10  such that the body portion  56  of the alignment rod  55  and the first vertebra screw insertion assembly  10  are precisely positioned relative to one another. Consequently, the alignment rod  55  is precisely positioned relative to the first and second vertebra screw insertion assemblies  10  and  10 ′. 
         [0071]    After being precisely positioned relative to the first and second vertebra screw insertion assemblies  10  and  10 ′, the body portion  61  of the alignment rod  60  can be secured to each of the second vertebra screw insertion assemblies  10 ′. As shown in  FIG. 16 , this can be done by means of fasteners  70  that are threaded or otherwise secured to the generally U-shaped yokes  15  of the pedicle screws  12 . The fasteners  70  are conventional in the art and are inserted through each of the second vertebra screw insertion assemblies  10 ′ into engagement with the generally U-shaped yokes  15  of the pedicle screws  12 . When secured thereto, the fasteners  70  precisely position the pedicle screws  12  relative to the body portion  61  of the alignment rod  60 . As a result, the vertebrae to which each of the pedicle screws  12  are attached are positioned in accordance with the shape of the body portion  61  of the alignment rod  60 . 
         [0072]    Next, the second positioning tool  65  is removed from the first vertebra screw insertion assembly  10  by withdrawing it from the first positioning tool  60 . Then, the first positioning tool  60  is removed from the first vertebra screw insertion assembly  10 . The first positioning tool  60  can be used to remove the positioning post  57  from the alignment rod  55  by rotating the first positioning tool  60  before it is removed from the first vertebra screw insertion assembly  10 . As mentioned above, the positioning post  57  of the alignment rod  55  and the counterbore  64  of the first positioning tool  60  are formed having non-circular cross sectional shapes. By rotating the first positioning tool  60  before it is removed from the first vertebra screw insertion assembly  10 , the positioning post  57  can be snapped apart from the alignment rod  55 , thereby facilitating its removal when the first positioning tool  60  is removed from the first vertebra screw insertion assembly  10 . Thereafter, another fastener  70  can be threaded or otherwise secured to the generally U-shaped yoke  15  of the pedicle screw  12  to secure the first vertebra screw insertion assembly  10  into engagement with the generally U-shaped yoke  15  of the associated pedicle screw  12 . 
         [0073]      FIG. 17  illustrates the structure of the alignment rod  55  in detail. In this embodiment, the positioning post  57  and the body portion  56  of the alignment rod  55  are formed integrally from a single piece of material. As shown therein, a recessed area  58  may be provided between the positioning post  57  and the body portion  56  of the alignment rod  55  to facilitate the removal of the positioning post  57  from the body portion  56  as described above. Alternatively, as shown in  FIG. 18 , a modified positioning post  57 ′ and a modified body portion  56 ′ of an alignment rod  55  may be formed from separate pieces of material that are releasably connected together. For example, as shown therein, the modified positioning post  57 ′ and the modified body portion  56 ′ can have cooperating threaded portions  58 ′ and  59 ′ or other structures provided thereon that releasably connect them together. 
         [0074]    As discussed above, the intermediate portion  30  of the first vertebra screw insertion assembly  10  has a slot  36  extending axially throughout the length thereof to provide clearance for the alignment rod  55  to be installed in the first and second vertebra screw insertion assemblies  10  and  10 ′. In lieu of such slot  36 , however, the intermediate portion  30  of the first vertebra screw insertion assembly  10  with a movable section. In a first modified embodiment of the intermediate portion, indicated generally at  80  in  FIGS. 19 and 20 , the slot  36  has been replaced by a section  81  that is movable relative to the intermediate portion  80  about an axis that is generally transverse to the axial orientation thereof. In a second modified embodiment of the intermediate portion, indicated generally at  82  in  FIG. 21 , the slot  36  has been replaced by a section  83  that is movable relative to the intermediate portion  80  about an axis that is generally parallel to the axial orientation thereof. In both embodiments, the movable sections  81  and  83  are sized and shaped to provide clearance for the alignment rod  55  to be installed in the first and second vertebra screw insertion assemblies  10  and  10 ′. In both instances, the movable sections  81  and  83  may be movably supported on the associated intermediate portions  80  and  82  by any desired hinge or other mechanism. Also, in both instances, the movable sections  81  and  83  may be positively maintained in engagement with the remainders of the intermediate portions  80  and  82  by a retainer cap  84  or any other desired structure. 
         [0075]      FIG. 22  illustrates a portion of a second embodiment of a vertebra screw insertion assembly, indicated generally at  100 , in accordance with this invention. In this modified embodiment, the upper portions  40  and  40 ′ have been replaced with modified upper portions  140  and  140 ′. The outer surfaces of lower ends  143  and  143 ′ of the upper portions  140  and  140 ′ are respectively formed having pluralities of axial retaining structures  144  and  144 ′, similar in structure and operation to the plurality of axial retaining structures  44  and  44 ′ described above. Likewise, the upper portions  140  and  140 ′ also have slots  145  and  145 ′ that is similar in structure and operation to the slots  45  and  45 ′ described above. In this embodiment, however, the upper portions  140  and  140 ′ additionally have one or more apertures  146  and  146 ′ respectively formed therethrough. One or more alignment devices  147  can extend through these apertures  146  and  146 ′ to align the vertebra screw insertion assemblies with one another, similar to the alignment brackets  46  discussed above. In use, the upper portions  140  and  140 ′ are axially positioned at desired locations relative to the associated intermediate portions  30  and  30 ′ in the same manner and for the same purpose as described above. If desired, a positioning tool  150  can be used to facilitate the axial positioning of the upper portions  140  and  140 ′ at desired locations relative to the associated intermediate portions  30  and  30 ′. 
         [0076]      FIG. 23  is schematic sectional elevational view of portions of the first vertebra screw insertion assembly  10  illustrated in  FIG. 5 . As shown therein, the upper end  21  of the lower portion  20  is received axially within the lower end  32  of the intermediate portion  30 , and the lower end  43  of the upper portion  40  is received axially within the upper end  31  of the intermediate portion  30 . Alternatively, in a modified embodiment shown in  FIG. 24 , an upper end  221  of a lower portion  220  can be received axially about a lower end  232  of an intermediate portion  230 , and a lower end  243  of an upper portion  240  can be received axially within an upper end  231  of the intermediate portion  230 . 
         [0077]    The above detailed description of the present invention is given for explanatory purposes. It will be apparent to those skilled in the art that numerous changes and modifications other than those cited can be made without departing from the scope of the invention. Accordingly, the whole of the foregoing description is to be construed in an illustrative and not a limitative sense, the scope of the invention being defined by the appended claims.