Abstract:
An instrumentation kit for use in preparing a bone to receive a prosthetic component includes at least one first combination device, the at least one first combination device including a proximal portion configured to couple with a torque providing device and a distal portion configured to couple with a first instrument, the at least one first combination device pivotable between a first position whereat the proximal portion and the distal portion are (i) longitudinally aligned and (ii) configured to transfer a torque received by the proximal portion to the distal portion, and a second position whereat the proximal portion and the distal position are (i) not longitudinally aligned and (ii) configured to transfer a torque received by the proximal portion to the distal portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/051,026, entitled “Combination Reamer/Drill Bit for Shoulder Arthroscopy”, which was filed on Mar. 18, 2011, the entire contents of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to the field of orthopedics, and, more particularly, to glenoid component apparatuses for shoulder arthroplasty and methods for using them. 
     BACKGROUND 
     As depicted in  FIG. 1 , a typical shoulder or glenohumeral joint is formed in a human body where the humerus  10  movably contacts the scapula  12 . The scapula  12  includes a glenoid fossa  14  that forms a socket against which the head of the humerus  10  articulates. At this socket, the scapula  12  includes cartilage  16  that facilitates such articulation. Beneath the cartilage is subchondral bone  18  that forms a wall of a glenoid vault  20  that defines a cavity which contains cancellous bone  22 . The subchondral bone  18  that forms the glenoid vault  20  defines a glenoid rim  24  at a periphery of the glenoid vault  20  that is attached to the cartilage  16 . During the lifetime of a patient, the glenoid fossa  14  may become worn, especially at its posterior and/or superior portions thereby causing severe shoulder pain and limiting the range of motion of the patient&#39;s shoulder joint. To alleviate such pain and increase the patient&#39;s range of motion, a shoulder arthroplasty may be performed. Arthroplasty is the surgical replacement of one or more bone structures of a joint with one or more prostheses. 
     Shoulder arthroplasty often involves replacement of the glenoid fossa of the scapula with a prosthetic glenoid component. The conventional glenoid component typically provides a generally laterally or outwardly facing generally concave bearing surface against which a prosthetic humeral head (or, alternatively, the spared natural humeral head in the case of a glenoid hemi-arthroplasty) may bear during operation of the joint. The conventional glenoid component typically also includes a generally medially or inwardly projecting stem for fixing the glenoid component in a cavity constructed by suitably resecting the glenoid fossa  14  and suitably resecting cancellous bone  22  from the glenoid vault  20 . 
     The goal of shoulder arthroplasty is to restore normal kinematics to the shoulder. Accordingly, known systems attempt to replicate the normal kinematics by carefully controlling the geometry of the articulating surfaces in the joint as well as the positioning of the prostheses in the bones in which the prostheses are implanted. Thus, the articulating surface of a humeral component is typically spherical and positioning of the humeral component is accomplished by using the anatomical neck of the humerus as the reference plane for reconstruction of the humeral head. 
     Traditionally, shoulder joints have been understood to exhibit translation of the humeral component on the glenoid component in addition to rotation. Thus, the articulating surface of the glenoid is typically formed with a radius of curvature that is much larger than the radius of curvature of the humeral component. The increased radius of curvature of the glenoid articulating surface can be from 2-6 mm larger than the radius of curvature for the humeral component in these systems. 
     In known systems, the glenoid component is positioned in the geometric center of the glenoid fossa. The geometric center is established by generating a line from the most superior point of the glenoid rim to the most inferior point of the glenoid rim (“Saller&#39;s line”). A second line is generated between the most posterior point of the glenoid rim and the most anterior point of the glenoid rim. The intersection of the two generated lines is considered to be the geometric center of the area circumscribed by the glenoid rim. By way of example,  FIG. 2  depicts a sagittal view of the scapula  12 . In  FIG. 2 , Saller&#39;s line  30  extends between the most superior point  32  of the glenoid rim  24  to the most inferior point  34  of the glenoid rim  24 . A second line  36  extends from the most posterior point  38  of the glenoid rim  24  and the most anterior point  40  of the glenoid rim. The geometric center  42  of the glenoid fossa  14  is located at the intersection of the line  36  and Saller&#39;s line  30 . As used herein, the terms anterior, posterior, superior, and inferior, unless otherwise specifically described, are used with respect to the orientation of the scapula  12  as depicted in  FIG. 2 . 
     Once a surgeon determines the placement of the glenoid component, a guide pin is positioned through the glenoid fossa. A reamer is then used to shape the scapula to receive a glenoid component, typically by forming a cavity in the glenoid vault. For glenoid components including a center peg for fixation of the glenoid component within the glenoid vault, a bore is drilled using the guide pin as a guide. The guide pin is then removed. For glenoid components including offset pegs in addition to the center peg for fixation of the glenoid component within the glenoid vault, a drill guide is introduced into the prepared cavity and additional bores are drilled for each of the offset pegs. A trial glenoid component is then implanted in the prepared cavity and, if the fit appears to be satisfactory, the trial is removed and a glenoid component is implanted in the prepared cavity. 
     There exists a need for a simplified method of implanting a glenoid component. There is a further need for reducing the instrumentation required to properly prepare the scapula to receive a glenoid component. 
     SUMMARY OF THE INVENTION 
     The present invention in one embodiment provides an instrumentation kit for use in preparing a bone to receive a prosthetic component which includes at least one first combination device, the at least one first combination device including a proximal portion configured to couple with a torque providing device and a distal portion configured to couple with a first instrument, the at least one first combination device pivotable between a first position whereat the proximal portion and the distal portion are (i) longitudinally aligned and (ii) configured to transfer a torque received by the proximal portion to the distal portion, and a second position whereat the proximal portion and the distal position are (i) not longitudinally aligned and (ii) configured to transfer a torque received by the proximal portion to the distal portion. 
     In another embodiment, a method of preparing a shoulder to receive a glenoid component includes accessing a glenoid of a shoulder, rotationally coupling a distal portion of a combination device to an instrument, applying a torque to a proximal portion of the combination device, transferring the applied torque from the proximal portion to the distal portion through a pivoting connection, rotating the instrument using the transferred applied torque, and reaming a portion of the glenoid with a rotating reaming section of the instrument using the transferred applied torque. 
     The above-noted features and advantages of the present invention, as well as additional features and advantages, will be readily apparent to those skilled in the art upon reference to the following detailed description and the accompanying drawings, which include a disclosure of the best mode of making and using the invention presently contemplated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a coronal view of an anatomically normal shoulder joint. 
         FIG. 2  depicts a sagittal view of the shoulder joint of  FIG. 1 ; 
         FIG. 3  depicts a bottom perspective view of a circular glenoid component that may be implanted in a scapula in accordance with principles of the invention; 
         FIG. 4  depicts a bottom plan view of the circular glenoid component of  FIG. 3 ; 
         FIG. 5  depicts a side plan view of the circular glenoid component of  FIG. 3 ; 
         FIG. 6  depicts a side perspective view of a combination reamer/drill device that may be used to simultaneously form a bore for receiving a peg of a glenoid component and to ream a glenoid fossa to receive the glenoid component; 
         FIG. 7  depicts a bottom perspective view of the combination device of  FIG. 6  showing the guide bore extending from a distal tip of the combination device; 
         FIG. 8  depicts a bottom plan view of the combination device of  FIG. 6 ; 
         FIG. 9  depicts a side plan view of the combination device of  FIG. 6  showing the guide bore extending to a drive section which in this embodiment is a hexagonally shaped bore in a body section of the combination device; 
         FIG. 10  depicts a perspective view of a combination power extension/anti-rotation handle which may be used with the combination device of  FIG. 6  to couple a power rotary tool (not shown) to the combination device; 
         FIG. 11  depicts a bottom plan view of the combination power extension/anti-rotation handle of  FIG. 10  showing a guide bore which extends from a distal tip of the lower portion; 
         FIG. 12  depicts a side cross sectional view of the combination power extension/anti-rotation handle of  FIG. 10 ; 
         FIG. 13  depicts a medical procedure that may be used to implant the circular glenoid component of  FIG. 3  into a scapula using the combination device of  FIG. 10 ; 
         FIG. 14  depicts a perspective view of the scapula of  FIG. 2  with a guide wire positioned in the scapula using a guide template and a guide template manipulator; 
         FIG. 15  depicts a partial cross-sectional view of the scapula of  FIG. 14  with the combination reamer/drill device of  FIG. 6  guided to a location adjacent to the glenoid fossa by the guide wire of  FIG. 14 ; 
         FIG. 16  depicts a partial cross-sectional view of the scapula of  FIG. 14  with the combination power extension/anti-rotation handle of  FIG. 10  coupled to the combination reamer/drill device of  FIG. 6 , both the combination power extension/anti-rotation handle and the combination reamer/drill device guided to a location adjacent to the glenoid fossa by the guide wire of  FIG. 14 ; 
         FIG. 17  depicts a partial cross-sectional view of the scapula of  FIG. 14  and the coupled combination power extension/anti-rotation handle and the combination reamer/drill devices of  FIG. 16  after the combination reamer/drill device has been used to form a bore in preparation for implanting the glenoid component of  FIG. 3  into the scapula; 
         FIG. 18  depicts a partial cross-sectional view of the scapula of  FIG. 14  and the coupled combination power extension/anti-rotation handle and the combination reamer/drill devices of  FIG. 16  after the combination reamer/drill device has been used to simultaneously ream the glenoid fossa and form a bore in preparation for implanting the glenoid component of  FIG. 3  into the scapula; 
         FIG. 19  depicts a perspective view of the scapula of  FIG. 14  after the combination power extension/anti-rotation handle has been withdrawn along the guide wire  236  to a location that allows pivoting of the proximal portion of the combination power extension/anti-rotation handle; 
         FIG. 20  depicts a perspective view of the combination power extension/anti-rotation handle after the proximal portion of the combination power extension/anti-rotation handle has been pivoted; 
         FIG. 21  depicts a perspective view of the scapula of  FIG. 14  after the pivoted combination power extension/anti-rotation handle of  FIG. 20  has been guided by the wire guide of  FIG. 14  and coupled with the combination reamer/drill device of  FIG. 6  allowing a user to manually orient the combination reamer/drill device on the scapula; 
         FIG. 22  depicts a perspective view of the scapula of  FIG. 14  with the combination reamer/drill device of  FIG. 6  used to guide a drill bit to form a bore to receive an offset peg of the glenoid component of  FIG. 3  while the pivoted combination power extension/anti-rotation handle of  FIG. 20  has been used to manually stabilize the combination reamer/drill device on the scapula; and 
         FIG. 23  depicts a perspective view of the combination reamer/drill device of  FIG. 6  and drill bit of  FIG. 22  with the pivoted combination power extension/anti-rotation handle of  FIG. 20 . 
     
    
    
     DETAILED DESCRIPTION 
     Like reference numerals refer to like parts throughout the following description and the accompanying drawings. 
       FIGS. 3-5  depict a glenoid component  100 . The glenoid component  100  includes a body portion  102  including a spherical articulating surface  104  and an opposite bone contacting surface  106 . An outer wall  108  extends away from the bone contacting surface  106  and defines an outer periphery of the body portion  102 . The bone contacting surface  106  is generally convex. A finned center peg  110  extends away from the nadir of the bone contacting surface  106  as viewed in  FIG. 5 . Three offset pegs  112 ,  114 , and  116  extend away from the bone contacting surface  106  at locations between the center peg  110  and the outer wall  108 . The nadir  118  of the spherical articulating surface  104  is located on the centerline  120  of the glenoid component  100 . 
     The glenoid component  100  in this embodiment is an integrally formed unit made from a durable biocompatible plastic or any other suitable durable biocompatible material. For example, the glenoid component  100  may be made from a polyethylene. One particular polyethylene that is well suited for glenoid component  100  is a high molecular weight polyethylene, for example ultra-high molecular weight polyethylene (“UHMWPE”). One such UHMWPE is sold as by Johnson &amp; Johnson of New Brunswick, N.J. as MARATHON™ UHMWPE and is more fully described in U.S. Pat. Nos. 6,228,900 and 6,281,264 to McKellop, which are incorporated herein by reference. 
     In embodiments wherein the articulating surface  104  and the other portions of the glenoid component  100  are made from different materials, the portions of the glenoid component  100  other than the articulating surface  104  may be made from a suitable biocompatible metal such as, for example, a cobalt chromium alloy, a stainless steel alloy, a titanium alloy, or any other suitable durable material. In these embodiments, the articulating surface  104  is secured to the body portion  102  in any suitable manner. For example, articulating surface  104  may be bonded to body portion  102 , or articulating surface  104  could be made from polyethylene and compression molded to body portion  102 . Alternately, the articulating surface  104  may be glued to the body portion  102  by, for example, an adhesive. Alternatively, articulating surface  104  may be mechanically interlocked to the body portion  102  by taper locking or otherwise press-fitting the articulating surface  104  into the body  102  and the body  102  may include any other suitable interlocking features, for example, rib(s), lip(s), detent(s), and/or other protrusion(s) and mating groove(s), channel(s), or indent(s) (not shown). 
     In alternative embodiments, one or more of the outer wall  108 , the bone contacting surface  106 , the center peg  110  and the offset pegs  112 ,  114 , and  116  may include a porous coating to facilitate bone in-growth into the glenoid component  100 . The porous coating may be any suitable porous coating and may for example be POROCOAT®, a product of Johnson &amp; Johnson of New Brunswick, N.J. and more fully described in U.S. Pat. No. 3,855,638 to Pilliar, which is incorporated herein by reference. 
     In order to implant the glenoid component  100  into a scapula, the scapula must first be prepared to receive the glenoid component  100 . A device which can be used to prepare the scapula to receive the glenoid component  100  is depicted in  FIGS. 6-9 . With reference to  FIGS. 6-9 , a combination reamer/drill device  130  includes a drive section  132 , a body section  134 , and a drill or boring section  136 . The drive section  132  in this embodiment is a hexagonally shaped bore defined in the body section  134 . 
     A number of reaming fins  140  extend from the lower central portion of the body section  134  toward the drill section  136 . The reaming fins  140  curve proximally and outwardly from the lower central portion of the body section  134  to the outer periphery of the body section  134 . The reaming fins  140  include an arcuate leading edge  142 . The body section  134  defines a number of through-holes at locations between adjacent reaming fins  140 . The through-holes in the embodiment of  FIGS. 6-9  include three drill guides  146  and three ports  148 . 
     The drill section  136  extends away from the body section  134  to a distal tip  150 . Two flutes  152  and  154  extend helically about the drill section  136  between the body section  134  and the distal tip  150 . A guide bore  156  extends from the distal tip  150  to the drive section  132 . 
     As discussed in further detail below, a kit may include one or more combination reamer/drill devices  130  along with various instrumentation to facilitate use of the combination reamer/drill device  130 . By way of example,  FIGS. 10-12  depict a combination power extension/anti-rotation device  160  that may be included in the kit. The combination power extension/anti-rotation device  160  includes a longitudinally extending proximal portion  162  and a longitudinally extending distal portion  164 . The proximal portion  162  includes a power receiving portion  166  and a junction portion  168 . The power receiving portion  166  is sized and configured to couple with a power tool (not shown) and includes a pair of opposing power receiving flats  170  and a pair of coupling grooves  172  and  174  which extend about the power receiving portion  166  between the power receiving flats  170 . 
     The junction portion  168  includes two tines  180 / 182  which define a receiving area  184  therebetween. A guide bore  186  extends from the receiving area  184  to the proximal tip  188  of the proximal portion  162 . Two bores  190 / 192  extend through the respective tines  180 / 182 . 
     The distal portion  164  includes a power transfer portion  200  at a distal end  202 . The power transfer portion  200  is shaped to be complimentary to the drive section  132  of the combination reamer/drill  130 . In the embodiment of  FIGS. 10-12 , the power transfer portion  200  is thus a hexagonally shaped protrusion sized to fit within the drive section  132 . 
     A junction portion  204  is located at a proximal end  206  of the distal portion  164 . The junction portion  204  includes two tines  208 / 210  which define an upper receiving area  212  and a lower receiving area  214  therebetween. A guide bore  216  extends from the lower receiving area  214  to the distal end  202  of the distal portion  164 . Two bores  218 / 220  extend through the respective tines  208 / 210 . The bores  218 / 220  are countersunk so that two pins  222 / 224  may be received therein and be flush with the outer surface of the tines  208 / 210 . 
     When the combination power extension/anti-rotation handle  160  is assembled, the tines  180 / 182  of the proximal portion  162  are received with in the upper receiving area  212  of the distal portion  162 . Additionally, the bores  190 / 192  are aligned with the bores  218 / 220 , respectively. The pin  222  is positioned within the aligned bores  190 / 218 , while the pin  224  is positioned within the aligned bores  192 / 220 . The pins  222 / 224  and bores  190 / 192 / 218 / 220  are configured to allow the proximal portion  162  to pivot with respect to the distal portion  164  about an axis defined by the pins  222 / 224 . To this end, the pins  222 / 224  in one embodiment are in the form of rivets. In another embodiment, the pins  222 / 224  are threadedly engaged with the bores  190 / 192 , respectively and configured to articulate with the bores  218 / 220 . 
     Additionally, the guide bore  186  and the guide bore  216  lie within the same plane when the combination power extension/anti-rotation handle  160  is assembled. As the proximal portion  162  is pivoted with respect to the distal portion  164 , the guide bore  186  pivots within that same plane. Accordingly, the guide bores  186  and  216  may be pivoted into alignment with each other. When the guide bores  186  and  216  are aligned, the proximal portion  162  and the distal portion  164  are longitudinally aligned as depicted in  FIG. 10 . 
     A kit including the combination reamer/drill device  130  and the power extension/anti-rotation handle  160  may be used in preparing a shoulder to receive a glenoid component such as glenoid component  100  in accordance with a procedure  230  depicted in  FIG. 13 . Initially, a scapula is accessed at block  232  in accordance with a desired surgical approach. At block  234 , a guide wire, which may be provided in a kit along with other instrumentation used in the procedure  230 , is positioned on the scapula. Positioning of the guide wire may be computer aided. In one embodiment, the guide wire is positioned based upon identification of the center of an inferior glenoid circle. By way of example,  FIG. 14  depicts a guide wire  236  implanted into a glenoid  238  of a scapula  240 . In the embodiment of  FIG. 20 , the guide wire  236  has been positioned with the aid of a guide plate  242  and a guide plate manipulator  244 . 
     Once the guide wire is positioned, a combination reamer/drill device  130  is positioned with the guide bore  156  aligned with the guide wire  236 . The combination reamer/drill device  130  is then moved toward the guide wire  236  and at block  246  the guide wire  236  is used to guide the combination reamer/drill device  130  to a location adjacent to the glenoid  238  of the scapula  240  as depicted in  FIG. 15 . 
     At block  248 , a combination power extension/anti-rotation handle  160  is coupled to the combination device  130  by first aligning the guide bore  216  (see  FIG. 12 ) with the guide wire  236 . The combination power extension/anti-rotation handle  160  is then moved over the guide wire  236  until the guide wire  236  extends through the guide bore  216  and into the lower receiving area  214 . The proximal portion  162  is then pivoted with respect to the distal portion  164  as necessary to align the guide bore  186  with the guide wire  236 . The combination power extension/anti-rotation handle  160  is then moved over the guide wire  236  until the power transfer portion  200  is adjacent to the drive section  132  of the combination reamer/drill device  130 . If needed, the combination power extension/anti-rotation handle  160  is rotated on the guide wire  236  to rotationally align the shaped power transfer portion  200  with the shaped drive section  132  and the power transfer portion  200  is inserted into the drive section  132  resulting in the configuration of  FIG. 16 . 
     A rotary tool (not shown) is then coupled to the combination power extension/anti-rotation handle  160  at block  250 . Thus, the rotary tool is coupled to the power receiving portion  166  of the proximal portion  162  so as to be indirectly coupled to the combination reamer/drill device  130 . 
     Power is then applied to the rotary tool causing the rotary tool to rotate the combination power extension/anti-rotation handle  160 . Rotary force is transferred to the drive section  132  of the combination reamer/drill device  130  through the power transfer portion  164  (see  FIG. 12 ). More specifically, torque is passed from the rotary tool to the power receiving portion  166 . The tines  180 / 182 / 208 / 210  are configured such that the torque received by the proximal portion  162  is transferred to the tines  208 / 210  through the tines  180 / 182 . The torque is then transferred from the power transfer portion  200  to the drive section  132 , causing the combination reamer/drill device  130  to rotate. 
     As the combination reamer/drill device  130  initially rotates about the guide wire  236 , the drill section  136  contacts the glenoid  238  and begins to bore a hole in the glenoid  238 . The reaming fins  140 , however, are initially spaced apart from the glenoid  238  as depicted in  FIG. 17 . Accordingly, no reaming occurs. As a hole is formed in the glenoid  238  by the drill section  136 , the combination reamer/drill device  130  is guided by the guide wire  236  such that the reaming fins  140  come into contact with the glenoid  238  as depicted in  FIG. 18 . Continued rotation of the combination reamer/drill device  130  with the rotary tool thus causes simultaneous reaming of the glenoid  238  with the reaming fins  140  and boring of the scapula  240  with the drill section  136  at block  252 . 
     Once the glenoid  238  has been reamed to the desired depth, the power tool is de-energized and disconnected at block  254 . The size of the drill section  132 , both in length and diameter, is selected to be complimentary to the size of the center peg  110  of the glenoid component  100 . Thus, upon completion of the reaming, the bore formed by the drill section  132  is sized to receive the finned center peg  110 . 
     The combination power extension/anti-rotation handle  160  is then backed away from the combination reamer/drill device  130  along the guide wire  236  at block  256  until the end of the guide wire  126  is located within the receiving area  184  of the proximal portion  162  resulting in the configuration of  FIG. 19 . While the guide wire was within the guide bore  186  of the proximal portion  162 , the proximal portion  162  was maintained in alignment with the distal portion  164  which enables smooth transfer of torque through the combination power extension/anti-rotation handle  160 . Once the guide wire  236  is no longer within the guide bore  186 , however, the proximal portion  162  may be pivoted with respect to the distal portion  164  to the configuration of  FIG. 20  (block  258 ). 
     At block  260 , the combination power extension/anti-rotation handle  160  is coupled to the combination device  130  substantially in the manner described above. Since the guide wire  236  does not extend through the proximal portion  162 , however, the proximal portion  162  may be used as a handle to rotate the coupled combination power extension/anti-rotation handle  160  and combination reamer/drill device  130  about an axis defined by the guide wire  236  as indicated by the arrow  262  of  FIG. 21 . The combination power extension/anti-rotation handle  160  is thus used to align a drill guide  146  in the combination reamer/drill device  130  with a desired location (block  264 ). In one embodiment, a handle similar to the handle shown attached to the guide plate manipulator  244  of  FIG. 14  may be included in the kit. Such a handle may be removably coupled to the power receiving portion  166  of the proximal portion  162  to facilitate manipulation of the combination power extension/anti-rotation handle  160 . 
     The ability to pivot the proximal portion  162  provides a surgeon with a relatively unobstructed view of the combination reamer/drill device  130 . Accordingly, the surgeon may view the reamed surface of the glenoid  238  through the drill guides  146 . This allows a surgeon to view the location in the scapula  240  at which the offset fixation pegs  112 ,  114 , and  116  of the glenoid component  100  will be anchored. In the embodiments in this example wherein the number and positioning of the drill guides  146  are complimentary to the number and positioning of the offset fixation pegs  112 ,  114 , and  116 , the surgeon may orient the combination reamer/drill device  130  such that each of the drill guides  146  is aligned with portions of the scapula  240  that can provide a good anchor for the offset fixation pegs  112 ,  114 , and  116 . 
     Once the combination reamer/drill device  130  is aligned at the block  264 , a drill bit is inserted through one of the drill guides  146  to drill an additional bore at a location spaced apart from the first bore formed using the drill section  136  at block  230 . By way of example,  FIGS. 22 and 23  depict a drill bit  266  positioned in a drill guide  146  of the combination device  130 . The combination power extension/anti-rotation handle  160  may be used to steady the combination reamer/drill device  130  during the drilling process. The offset of the proximal portion  162  from the axis defined by the wire guide  236  results in a mechanical advantage in maintaining the combination reamer/drill device  130  at the desired orientation. Blocks  264  and  268  may be repeated as desired to form additional holes. 
     Once all of the desired holes are formed, the combination reamer/drill device  130  is removed at block  270 . The combination power extension/anti-rotation handle  160  may be used to aid in removal of the combination reamer/drill device  130 . At block  272 , the glenoid component is implanted. In this example, the glenoid component  100  has a lower bone contacting surface  106  shaped complimentary to the reaming cross-section of the reaming fins  140 . Thus, in this example the lower bone contacting surface  106  is curved complimentary to the distal curve of the reaming fins  140 . In other embodiments, the reaming fins  140  may be configured to produce a flat bottomed area if a glenoid component with a flat lower bone contacting surface is used. Accordingly, a kit in one embodiment includes different combination devices with differently shaped reaming cross-sections. 
     Moreover, while in the embodiment of  FIGS. 10-12  the proximal portion  162  is only pivotably connected to the distal portion  164 , in another embodiment the proximal portion is both pivotably and slidably connected to the distal portion. This can be accomplished by providing longitudinal slots connected to the bores  218 / 220 . In this embodiment, once the proximal portion is aligned with the distal portion, the proximal portion may be moved toward the distal portion. Accordingly, in addition to torque being passed through the tines in the junction portion, additional features may be incorporated in the proximal and distal portions which are selectively interlocked. This arrangement allows for a more robust connection between the proximal portion and the distal portion which is useful in embodiments wherein weaker materials are desired to be used in forming a combination power extension/anti-rotation handle. 
     In yet another embodiment, the guide bores in the proximal portion and the distal portion are positioned substantially immediately adjacent to one another when the proximal and distal portions are aligned. In this embodiment, pivoting between the proximal and distal portions is enabled by moving the combination power extension/anti-rotation handle such that the wire guide does not extend into the guide bore in the proximal portion. 
     The foregoing description of the invention is illustrative only, and is not intended to limit the scope of the invention to the precise terms set forth. Further, although the invention has been described in detail with reference to certain illustrative embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.