Abstract:
To avoid traditional muscle dissection required in the placement of a screw for a pedicle screw fixation, a retractor is provided having a guide of an appropriate length to provide access from the skin surface to the dorsal aspect of the vertebra over the pedicle. The retractor has a handle to provide appropriate holding leverage and to maintain the guide so as to stabilize the guide against the lateral aspects of the facet with the paraspinous musculature. The retractor has a channel of an appropriate size to accommodate a variety of tools, including a drill bit or a tap. The channel also provides a pathway for a probe or feeler to inspect the placement of the screw. A tool groove may be provided in the channel to support the shaft of a tool, such as a tap.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. application Ser. No. 10/060,905 filed Jan. 29, 2002 entitled “Retractor And Method For Spinal Pedicle Screw Placement” which claimed priority from U.S. Provisional Patent Application No. 60/264,943 filed Jan. 29, 2001 entitled “Retractor And Method For Spinal Pedicle Screw Placement”, and this application also claims priority from U.S. Provisional Patent Application No. 60/380,345 filed May 13, 2002 entitled “Retractor and Method for Spinal Pedicle Screw Placement” all of which are incorporated herein by reference in their entireties. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is directed to a novel retractor and a method using such retractor for placing spinal pedicle screws.  
         SUMMARY OF THE INVENTION  
         [0003]    Pedicle screw fixation has become an important part of stabilizing the spine to assist in arthrodesis. Traditionally a significant amount of muscle dissection has been required to prepare for screw placement. Recently, various approaches have been developed to minimize unnecessary disturbance of paraspinous structures while still accomplishing satisfactory fixation of the spine and the concomitant grafting necessary to achieve arthrodesis.  
           [0004]    The retractor of the present invention eases intermuscular placement of pedicle screws by providing a minimally invasive approach, and specifically lends itself to image guided applications. The characteristics of the retractor are described below with accompanying figures to illustrate the features.  
           [0005]    The retractor&#39;s guide channel is of an appropriate length to provide access from the skin surface to the dorsal aspect of the vertebra over the pedicle. The handle of the retractor is attached to provide appropriate holding leverage to maintain the position of the retractor and to stabilize its guide portion against the lateral aspect of the facet with the paraspinous musculature.  
           [0006]    An elongated insert may be placed within the guide channel of the retractor. The insert provides a working channel or hollow bore of an appropriate size to accommodate various instruments. For example, the working channel may receive an awl or perforator for the bony cortex, a drill for the pedicle if desired, or a tap for the pedicle and body of the vertebra. The working channel also provides a pathway for a probe or feeler to inspect the placement of the screw. Additionally, the insert may be configured to allow for guided instruments to confirm position of the screw placement. Moreover, attachment of a tracker to the retractor, the insert, or to instruments used through the insert allows coupling of the surgical procedure with an image guided system.  
           [0007]    The retractor is configured such that removal of the insert from the guide channel of the retractor provides a protected working channel for placement of the pedicle screw. The tip of the retractor may be textured and obliquely cut to help maintain position of the retractor against the lateral aspect of the facet. The guide channel is preferably open on one side to allow removal of the retractor after placement of the screw. The channel is of sufficient length to maintain muscle retraction necessary for screw placement.  
           [0008]    The shape of the distal end of the retractor aids easy placement of the retractor with minimal muscle separation, thus helping to displace soft tissues while placing the retractor and minimizing the tendency of the retractor to catch on soft tissue during entry. Preferably, there are projections and a textured distal surface to help maintain position against the bone and to avoid displacement while working through the retractor. The cutout, preferably semicircular or curved, at the distal end is of an appropriate size to allow use of a tap and subsequent placement of a pedicle screw.  
           [0009]    In a separate aspect of the invention, a retractor including a tool groove is provided, wherein the tool groove is used to assist a surgeon in guiding a tool to the interior surgical work site. The tool groove may occupy only a portion of the length of the guide portion of the retractor, or it may extend the entire length of the guide portion of the retractor.  
           [0010]    In yet a separate aspect of the invention, a retractor including a guide wire channel is provided.  
           [0011]    Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a perspective view of one embodiment of the retractor of the present invention, and front and rear views of an embodiment of the insert for the retractor;  
         [0013]    [0013]FIG. 1 a  is an enlarged view of the distal end of the retractor;  
         [0014]    [0014]FIG. 2 is a front elevation view of the retractor of FIG. 1, taken along arrow  15 , of one embodiment of the insert for the retractor adapted for use with a surgical tap, and a surgical tap;  
         [0015]    [0015]FIG. 3 is a vertical cross-sectional view of the retractor and an insert mounted within the retractor;  
         [0016]    [0016]FIG. 4 is a horizontal cross-sectional view of the retractor taken along line  4 - 4  of FIG. 3 and an insert mounted within the retractor;  
         [0017]    [0017]FIG. 5 is perspective view of the retractor of the present invention during use in a human spine wherein an insert is placed within the retractor and a tap is inserted through the insert;  
         [0018]    [0018]FIG. 6 is another perspective view of the retractor, with the insert removed and the retractor being used as a guide for emplacement of a pedicle screw;  
         [0019]    [0019]FIG. 7 is a perspective view of a further embodiment of the present invention having a recessed and curved distal tip at its guide portion;  
         [0020]    [0020]FIG. 8 is a perspective view of the retractor of the present invention fitted with an image tracker on the retractor&#39;s handle, shown in simulated application with the human spine;  
         [0021]    [0021]FIG. 9 is a perspective view of a separate embodiment of the present invention having a partial-length tool groove;  
         [0022]    [0022]FIG. 10 is a front elevation view of the retractor depicted in FIG. 9 along arrow  15 ;  
         [0023]    [0023]FIG. 11 is a perspective view of a separate embodiment of the present invention having a full-length tool groove;  
         [0024]    [0024]FIG. 11 a  is a detail drawing of the rounded tip of the device depicted in FIG. 11;  
         [0025]    [0025]FIG. 12 is a front elevation view of the retractor depicted in FIG. 11 along arrow  15 ;  
         [0026]    [0026]FIG. 13 is a perspective view of a further embodiment of the present invention having a recessed and curved distal tip at its guide portion and a partial-length tool groove;  
         [0027]    [0027]FIG. 14 is a perspective view of a further embodiment of the present invention having a recessed and curved distal tip at its guide portion and a full-length tool groove;  
         [0028]    [0028]FIG. 15 is an enlarged partial side elevation view of the bend between the handle and the guide portion of a retractor, wherein a partial-length tool groove is shown;  
         [0029]    [0029]FIG. 16 a  is a side elevation view of a separate embodiment of the present invention;  
         [0030]    [0030]FIG. 16 b  is a front elevation view of the device shown in FIG. 16 a;    
         [0031]    [0031]FIG. 16 c  is a cross section of the guide portion of the device of FIG. 16 b  taken along line  16   c - 16   c;    
         [0032]    [0032]FIG. 16 d  is a cross section of the guide portion of the device of FIG. 16 b , but with an interior hole and without a side slot;  
         [0033]    [0033]FIG. 17 a  is a front elevation view of a guide wire;  
         [0034]    [0034]FIG. 17 b  is a front elevation view of a dilator for the guide wire shown in FIG. 17 a;    
         [0035]    [0035]FIG. 17 c  is a front elevation view of yet a larger cylindrical dilator as compared to the dilator shown in FIG. 17 b;    
         [0036]    [0036]FIG. 17 d  is a cross-section taken through line  17   d - 17   d  of FIG. 17 b;  and  
         [0037]    [0037]FIG. 17 e  is a cross-section taken through line  17   e - 17   e  of FIG. 17 c.    
     
    
     DETAILED DESCRIPTION  
       [0038]    With reference to FIG. 1, retractor  10  of the present invention is depicted in a perspective view. Retractor  10  preferably comprises two portions, a handle  12  and a guide portion  14 . Handle  12  is attached to the proximal end of guide portion  14 . Handle  12  may be of various configurations to allow access to the surgical site while providing a means of gripping the retractor  10  such that sufficient leverage may be applied to maintain the desired orientation of retractor  10  at the surgical site. In a preferred embodiment, handle  12  is oriented at an angle of between about 90 and about 135 degrees from the guide portion  14 . Handle  12  may include a slot  18  for interconnecting an attachment or a supplemental handle using handle screws  20 . Provision of slot  18  allows for various supplemental handle configurations to be used with retractor  10  to provide different holding leverages, as well as to provide interchangeable geometries that may be desired to overcome spatial constraints imposed by a specific patient&#39;s physical attributes. Alternately, an image tracker may be attached to slot  18  as discussed further below.  
         [0039]    Guide portion  14  is used for access to the interior of the surgical site. Typically, an incision is made in the patient&#39;s skin and muscle. Subsequently, the guide portion  14  is inserted through the exterior portion of the incision to create and maintain access to the interior targeted body part, such as the patient&#39;s spine. As described below, specific features of guide portion  14  provide for improved access to the spine.  
         [0040]    Guide portion  14  is preferably half-cylinder or U-shaped. More particularly, the rear surface  16  of guide portion  14  is preferably convex when viewing retractor  10  from the rear side of retractor  10 . The U-shaped front of guide portion  14  includes a hollow region or guide channel  22 . Guide channel  22  extends from the distal end  23  of guide portion  14  up to and including the upper-most or proximal end of guide portion  14 . In this manner, guide channel  22  maybe used to guide surgical tools and implants from the exterior of the surgical site down to the interior-most portion of the surgical site by inserting surgical tools down through the guide channel.  
         [0041]    The distal end  23  of guide portion  14  includes a rounded tip  24 . In addition, the distal end  23  of guide portion  14  is shown as being truncated obliquely along the lower medial face  25  to more closely approximate the lateral aspect of the facet of the paraspinous musculature of the patient, and provide for improved medial positioning of the guide portion  14  for placement of a drill and/or tap into the bony structure of the patient. The rounded tip  24  may further include a cutout or an opening  26  at its end. In a preferred embodiment shown in FIG. 1 a,  opening  26  is semicircular. One or more projections  27  may be provided around the end-most portion of opening  26  to aid in maintaining the position of the retractor  10  during use by stabilizing retractor  10  against the bony surface of the vertebrae. In addition, texturing such as ridges and grooves or machined points may be placed on the medial surface  29  of the lower medial face  25  of guide portion  14  to further stabilize retractor  10  when in use.  
         [0042]    Referring now also to FIGS. 2 and 4, to aid in facilitating use of tools at the distal end of guide portion  14 , an insert  30  may be placed within guide channel  22  to assist the surgeon in guiding and aligning tools along the desired orientation. In a preferred embodiment, insert  30  is generally triangular-shaped and has an aperture or hollow bore  32 . Hollow bore  32  allows various tools to be guided down to the targeted area within the surgical site, such as tap  33 .  
         [0043]    Triangular-shaped insert  30  includes base edges  34 . Base edges  34  of insert  30  cooperate with grooves  36  located within guide channel  22  to stabilize insert  30  within guide channel  22 . Base edges  34  are simply side projections which mate with the grooves  36 . Alternately, in lieu of base edges  34 , insert  30  may include one or more discontinuous side projections (not shown). Similar to the base edges  34  of insert  30 , these side projections could cooperate with a corresponding number of discontinuous grooves (not shown) located within guide channel  22  to aid in stabilizing insert  30  within guide channel  22 .  
         [0044]    Insert  30  includes a distal tip  38 , a longitudinal shaft  40 , a proximal end  42 , and an optional handle  43 . The distal tip  38  of insert  30  maybe rounded, defining a perimeter edge  44 . Perimeter edge  44  cooperates with the lower distal portion of groove  36  within guide channel  22  to further stabilize the distal tip  38  of insert  30 , and to further prevent unnecessary entanglement with the patient&#39;s bodily tissues when inserting the insert  30  into the guide channel  22 .  
         [0045]    Referring now to FIGS. 3 and 4, the retractor  10  of the present invention is shown with insert  30  received in the retractor  10 . As described above, the base edges  34  of the triangular-shaped insert  30  mate with corresponding grooves  36  in the guide channel  22  of retractor  10 . The distal tip  38  of insert  30  mates with the distal end  23  and rounded tip  24  of retractor guide portion  14  such that insert  30  does not extend beyond distal end  23 . FIGS. 3 and 4 also depict the hollow bore  32  through which a drill or tap  33  is inserted, thereby guiding the tap  33  to its targeted location.  
         [0046]    With reference to FIG. 5, a tap  33  is shown inserted though the bore  32  of the insert  30 , and the insert is placed in the guide channel  22  of retractor  10 . Tap  33  is used to create an appropriate bore in the bone “B” for receipt of a medical device, such as a pedicle screw “S”. Tap  33  may be sized in diameter to restrict passage of the tap  33  beyond a specified length through insert  30 . Specifically, tap  33  may contain a larger diameter section  50  which prevents passage of the tap  33  beyond the proximal opening  42  of insert  30 .  
         [0047]    With reference now to FIG. 6, once the tapping operation is complete, tap  33  and insert  30  may be removed from guide channel  22 . Guide channel  22  remains in place and is then used to guide a medical device, in this case, a pedicle screw S. The retractor  10  thus provides for proper alignment of the screw S. Further, the opening  26  in the distal end  23  of guide channel  22  is sized and shaped to accommodate the shank of screw S so that screw S may be properly aligned with the bore created by tap  33 . Tool T, such as a medical screwdriver, is then used to finish installation of screw S by screwing screw S into bone B.  
         [0048]    Referring now to FIG. 7, in a further embodiment, a retractor  10 ′ without a rounded tip is illustrated. As shown, the retractor has a recessed and curved distal tip  54 . This embodiment offers the advantage of offering a U-shaped guide channel  22 ; however, a rounded tip is not present to interfere with visibility of the surgical site. The U-shaped guide channel  22  extends from the upper end of guide portion  14  down to the distal end  23  of the guide portion  14 . As with the previous embodiment, distal end  23  of the guide portion  14  may be obliquely cut, with optional projections (not shown) formed at the end-most portion of the distal end  23 . Additional texturing may also be provided along the medial surface of guide portion  14  to assist with stabilizing retractor  10 ′ against the neighboring area of the surgical site.  
         [0049]    Due to the frequently limited amount of exposure of the spine or interior surgical area, the spinal implant procedures lend themselves to use of image guidance for surgery. Examples of such image guidance systems include the BrainLAB System and the Stealth System. As understood by those skilled in the art, these image guidance systems utilize a computer system with a monitor and two cameras that emit infrared signals, thereby determining the patient&#39;s position in the operating room as well as the position of the surgical instruments in relation to the patient&#39;s spine. The image guidance systems use data from standard CT or MRI scans to build a three dimensional image of the patient&#39;s spine. This model is then electronically matched to the patient&#39;s anatomy during surgery, allowing the surgeon, in effect, to see through tissue in order to accurately determine the placement of instruments or devices. During the operation, sensitive structures such as blood vessels and nerves, which the surgeon wants to avoid on the way to the anatomical target, can be visualized. In addition, during the operation the surgeon can follow the movements of his or her instruments on the computer screen in real time.  
         [0050]    Referring now to FIG. 8, retractor  10  is shown in one possible relationship with the human spine. The retractor  10  can be positioned at a desired location in relation to spinal processes and maintained in position with the projections  27  and texturing  28  which assist in anchoring the retractor on the patient. The insert  30  may then be used as a guide for subsequent tapping, or like operations. The retractor  10  with insert  30  provides a working channel for tracked instruments. Attachment of a tracker  60  directly to insert  30 , or alternately to the retractor handle  12  as shown in FIG. 8, allows a surgeon to guide the guide channel  22  of retractor  10 , or hollow bore  32  of insert  30  directly, and thus avoid tracking the instruments themselves, such as a drill or tap  33 .  
         [0051]    Referring now to FIG. 9, in yet a separate embodiment, retractor  10  includes a tool groove  70 . Tool groove  70  is sized to cradle a surgical tool, such as tap  33 , to assist a surgeon in aligning the tap  33  with a desired target location. More particularly, tool groove  70  is a second channel like feature that is formed in the guide channel  22  of guide portion  14 . Tool groove  70  may be a partial-length or full-length groove within guide portion  14 , as more fully described below.  
         [0052]    Referring still to FIG. 9, tool groove  70  may be formed in only a portion of guide portion  14 , such as the upper half or upper one-third of guide portion  14 . FIG. 10 provides a front elevation view of the embodiment of retractor  10  shown in FIG. 9. The view of FIG. 10 is taken in the general direction of arrow  15  of FIG. 9. FIGS. 9 and 10 illustrate that in one preferred embodiment, tool groove  70  tapers along a portion of the length of guide portion  14 , where it terminates at tool groove end  74 . More specifically, tool groove  70  may be of a variety of depths set into the interior back surface  72  of guide channel  22  of guide portion  14 . For example, tool groove  70  may be relatively shallow near handle  12 , such that it cradles only a portion of the shaft of a tool, or it may relatively deep near handle  12 , such that it cradles all or nearly all of the circumference of the tool. Furthermore, as shown in FIGS. 9 and 10, tool groove  70  may vary in depth along its length within guide portion  14 , such that it essentially terminates at a tool groove end  74  at some point along the length of guide portion  14 . In so doing, the back surface  76  of tool groove  70  serves as a guide plane for the shaft  52  of a surgical tool, such as tap  33 . The tool groove end  74  may terminate at different locations along the length of guide portion  14 , resulting in separate retractors  10  having tool grooves  70  with back surfaces  76  having different guide planes, thus yielding tool grooves  70  with back surfaces  76  having a variety of slopes or pitches.  
         [0053]    In use, after inserting the retractor  10  into an incision and exposing an internal surgical site, the surgeon places the shaft  52  of a tool, such as tap  33 , within tool groove  70  of the retractor  10 . The tool groove  70  supports the shaft  52  of tap  33 , thereby allowing the surgeon to better align the tap  33  with the patient&#39;s internal surgical site. If a tap  33  is used, the surgeon may rotate the tap  33  at the surgical site while maintaining the tap  33  in contact with the back surface  76  of tool groove  70 , thereby creating a precisely aligned hole for an implant, such as a pedicle screw S.  
         [0054]    In yet an alternate embodiment shown in FIGS. 11 and 12, retractor  10  may include tool groove  70 ′ that extends the full length of the guide portion  14 . FIG. 12 depicts a front elevation view along arrow  15  of the retractor  10  shown in FIG. 11. As with the embodiment shown in FIGS. 9 and 10, the embodiment shown in FIGS. 11 and 12 serves to support the shaft of a tool, such as the shaft  52  of tap  33 . Tool groove  70 ′ may maintain a constant depth along the back surface  72  of guide portion  14 , or it may vary in depth. Regardless of whether tool groove  70 ′ maintains a constant depth or varies in depth along the back surface  72 , the back surface  76 ′ of tool groove  70 ′ provides a plane against which the shaft of a tool maybe used by a surgeon to align the tool with the internal surgical site. Tool groove  70 ′ preferably aligns with opening  26  at the distal end  23  of guide portion  14 , as shown in FIG. 11 a.    
         [0055]    As shown in FIGS.  9 - 12 , the tool groove  70  or  70 ′ may be used with retractors  10  that have means for holding an insert  30 , such as grooves  36 . Thus, a retractor  10  incorporating a tool groove  70  or  70 ′, can be used in combination with an insert  30 , as previously described. As noted above, grooves  36  receive base edges  34  of insert  30  to hold insert  30  within guide channel  22 . When an insert  30  is used in combination with a retractor  10  having a tool groove  70  or  70 ′, the insert  30  fits in front of the tool groove  70  or  70 ′. Alternatively, retractor  10  may not include grooves  36 , and can be used without insert  30 . Nonetheless, retractor  10  can incorporate tool grooves  70  or  70 ′, and can also be combined with the features at the distal end  23  of guide portion  14 , such as the rounded tip  24 , opening  26 , projections  27 , and texturing along the medial surface  29  of the lower medial face  25 .  
         [0056]    Referring now to FIG. 13, retractor  10 ′ of FIG. 7 can be modified to include a tool groove  70  within its guide portion  14 . That is, a retractor  10 ′ without a rounded tip  24  can have a tool groove  70 . This separate embodiment of the present invention incorporates all of the features of the embodiment shown and described in conjunction with FIG. 7, but also includes the partial-length tool groove  70  that can be used to provide a cradle for the shaft of a tool, such as the shaft  52  of tap  33 , or the shaft  52  of a medical screwdriver T, as shown in FIG. 6.  
         [0057]    Referring now to FIG. 14, retractor  10 ′ of FIG. 7 can be modified to include a tool groove  70 ′ within its guide portion  14 . That is, a retractor  10 ′ without a rounded tip  24  can have a tool groove  70 ′. This separate embodiment of the present invention incorporates all of the features of the embodiment shown and described in conjunction with FIG. 7, but also includes the full-length tool groove  70 ′ that can be used to provide a cradle for the shaft of a tool, such as the shaft  52  of tap  33 .  
         [0058]    Referring now to FIG. 15, an enlarged partial side elevation view of the transition between the handle  12  and the guide portion  14  is shown. For the example shown in FIG. 15, a retractor having a partial tool groove  70  is depicted, with the tool groove  70  having a back surface  76 . The back surface  76  of tool groove  70  intersects a top surface  80  of the handle  12  at an angle θ. Also shown in FIG. 15 is the interior back surface  72  of the guide channel  22 . Interior back surface  72  of guide channel  22  forms an angle φ with the top surface of handle  22 . Preferably, angle θ is greater than angle φ, such that back surface  76  of tool groove  70  intersects the interior back surface  72  of guide channel  22  at tool groove end  74 . Thus, back surface  76  of tool groove  70  serves as an inset and alternately angled surface than that of the interior back surface  72  of guide channel  22 .  
         [0059]    Referring now to FIG. 16 a - 16   c , a separate embodiment of a retractor  82  is shown. Retractor  82  includes a guide portion  14  attached to handle  12 , where the guide portion  14  includes slot or wire channel  84 , as best seen in FIG. 16 c , where the slot or wire channel  84  is suited for placing a guide wire W, as shown in FIG. 17 a . Alternatively, as shown in FIG. 16 d,  the wire channel  84  can be enclosed on its sides with a hole  86  provided through its interior for the guide wire placement. Upon placing a guide wire W, retractor  82  can be withdrawn and subsequent access for tapping and/or pedicle screw placement can be performed by placing a dilator D, over the guide wire W, or a series of cylindrical dilators D 1  and D 2  as is shown in FIGS. 17 b  and  17   c . In addition, a separate retractor, such as retractor  10 ′, can then be placed against the dilator and slid into position with the rounded tip  24  of distal end  23  smoothly guiding the muscle from against the dilator to the outer surface of the retractor  10 ′. Cross sections of the cylindrical dilators shown in FIGS. 17 b  and  17   c  are depicted in FIGS. 17 d  and  17   e , respectively.  
         [0060]    Retractors  10  or  10 ′ incorporating a tool groove  70  or  70 ′ may be used in combination with an image tracker  60  as previously described. Retractor  82  may also incorporate an image tracker  60 .  
         [0061]    A plurality of retractors  10  or  10 ′ may be used by a surgeon, wherein the retractor&#39;s  10  or  10 ′ possess a variety of tool groove  70  or  70 ′ configurations that allow a surgeon to choose a retractor  10  or  10 ′ with a full-length tool groove  70 ′ within guide portion  14  or a partial-length tool groove  70  within guide portion  14 , and wherein the tool grooves  70  or  70 ′ may have different depths and pitches. Retractor  82  may be used prior to changing to retractor  10  or  10 ′.  
         [0062]    Alternatively, it is another aspect of the present invention that the guide portion  14  may be detachably connected at a connection point  78  to the handle  12 . Guide portion  14  is detachably connected to handle  12  preferably using screws, bolts, a quick connect coupling or some other means, thereby allowing various configurations of guide portions  14  to be interchangeably connected to the handle  12 . As a result, various guide portions  14  can be produced having a variety of tool groove  70  or  70 ′ configurations, and the surgeon can attach the desired guide portion  14  deemed appropriate for the given surgical conditions.  
         [0063]    All components of the invention and its various embodiments and alternatives described herein are manufactured of a material appropriate for surgical use. For example, the components can be made of stainless steel. However, it is to be understood that other types of materials may also be used, such as titanium or ceramics. Alternatively, it is yet an another aspect of the present invention that the retractor  10  may be manufactured of surgical quality plastics or other disposable materials. This manufacturing aspect allows for relatively inexpensive production of a surgically sterile retractor that can be disposed after each use. A surgeon can pick one or more retractor configurations having different guide portion arrangements for each individual surgery. Alternatively, disposable guide portions  14  can be produced for temporary attachment to a reusable handle  12 .  
         [0064]    While various embodiments of the present invention have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention.