Patent Publication Number: US-10758252-B2

Title: Retro guidewire reamer

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a division of co-pending U.S. patent application Ser. No. 14/198,900 filed Mar. 6, 2014, entitled RETRO GUIDEWIRE REAMER, which in turn claims benefit of the priority of U.S. Provisional Patent Application No. 61/776,896 filed Mar. 12, 2013, U.S. Provisional Patent Application No. 61/805,578 filed Mar. 27, 2013, and U.S. Provisional Patent Application No. 61/858,800 filed Jul. 26, 2013, the contents of which are incorporated by reference herein in their entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     The present application relates generally to surgical apparatus and methods, and more specifically to surgical apparatus and methods of creating tunnels through bone tissue during arthroscopic ligament reconstruction surgery. 
     BACKGROUND 
     Desired outcomes for arthroscopic ligament reconstruction surgery are generally achieved by establishing the proper shape and placement of torn tissue. In a typical arthroscopic procedure, however, a cruciate footprint is often hidden from view by soft tissue, as well as remnant cruciate tissue. Such an arthroscopic procedure typically includes debriding the soft tissue and/or the remnant cruciate tissue to visualize the repair site, and establishing approach angles through portals located on the patient&#39;s skin. The reconstruction can then be accomplished by creating bone tunnels through the patient&#39;s femur and tibia. These bone tunnels are subsequently filled with a tendon graft, replicating the original damaged tissue. 
     The typical arthroscopic procedure described above has shortcomings, however, due at least in part to problems pertaining to the lack of visualization, the approach angles, and the shape of the tendon graft. Although the shape of the tendon graft is generally not round, that is often the shape of the reconstructed repair. Because the approach angles are generally not perpendicular to the skin surface, however, the portals located on the patient&#39;s skin are often visualized as being elliptical, making proper placement of the bone tunnels through the patient&#39;s femur and/or tibia difficult to achieve. 
     While performing arthroscopic ligament reconstruction surgery, a surgeon typically makes a small incision in a patient&#39;s skin covering the surgical site, e.g., a bone joint, to allow a surgical instrument(s) to be placed in the bone joint and manipulated through arthroscopic visualization. One such surgical instrument can be configured to operate in both a drilling mode and a cutting mode. The surgical instrument includes a shaft, and a drill bit portion having a conical, multi-blade configuration. The drill bit portion is configured to engage with the shaft, and to articulate between a “straight” position approximately parallel to the longitudinal axis of the shaft, and a “flip” non-parallel position relative to the longitudinal axis of the shaft. While operating in the drilling mode, the surgical instrument can be employed in an antegrade manner with the conical, multi-blade drill bit portion in the straight parallel position relative to the shaft&#39;s longitudinal axis. While operating in the cutting mode, the surgical instrument can be employed in a retrograde manner with the conical, multi-blade drill bit portion in the flip non-parallel position relative to the shafts longitudinal axis. 
     For torn knee anterior cruciate ligament (ACL) reconstruction, there has been an evolution in the anatomic femoral placement at the reconstructed ACL. One approach to achieving proper placement of the reconstructed ACL includes creating a tunnel from the outside to the inside (i.e., from the “outside in”) of the patent&#39;s femur. With this approach, a guide can be used to establish a desired path for the femoral tunnel, and a guidewire can be placed along the desired path. A trans-tibial approach may then be employed, in which the knee is flexed to about 90°, the guide is placed in the center of the tibial footprint, and a tunnel is drilled through the tibia and extending into the femur. Alternatively, a flexible and/or retrograde drill may be employed, or the patient&#39;s knee may be hyper-flexed to allow the femoral and tibial tunnels to be drilled independent of one another. 
     Still another approach may be employed, in which the femoral/tibial tunnels are drilled through an anterior medial portal. With this approach, a curved guide can be used to place a guidewire, and an appropriately sized reamer can be advanced over the guidewire to create a bone tunnel. Alternatively, the patient&#39;s knee can be hyper-flexed to allow straight line drilling of the bone tunnel. A retro-drill can also be assembled inside the bone joint, and the bone tunnel can then be drilled in a retrograde manner. 
     SUMMARY 
     In accordance with the present application, surgical instruments and methods of using such surgical instruments (also referred to herein as a/the, “retro guidewire reamer(s)”) are disclosed. In a first aspect, a retro guidewire reamer includes at least one cutting member, and a mechanism operative to move the cutting member, by remote activation, from a closed position to an opened or deployed position and vice versa, thereby allowing for the creation a counter bore through bone tissue (e.g., a tibia, a femur). In an exemplary mode of operation, a surgeon establishes a path through the bone for a guidewire using a guide, places the guidewire along the path, and removes the guide. The surgeon then establishes the proper size of a bone tunnel to best fit a replacement tendon graft. Once the proper size of the bone tunnel is established, the surgeon uses the retro guidewire reamer with an appropriately sized drill bit to create a primary bone tunnel over, the guidewire from the outside in. Once the primary bone tunnel is drilled, the surgeon retracts the guidewire, and activates the mechanism to open or deploy the cutting member within the bone joint to conform to the established size of the bone tunnel for the replacement tendon graft. The surgeon then uses the retro guidewire reamer with the opened or deployed cutting member to create a counter bore through the bone in a retrograde manner. Once the counter bore is drilled, the surgeon activates the mechanism to close the cutting member, allowing the retro guidewire reamer to be withdrawn through the primary bone tunnel created by the drill bit. 
     In a second aspect, a retro guidewire reamer includes a tubular shaft having a distal end, at least one cutting member disposed adjacent the distal end of the tubular shaft, and a first mechanism operative to move the cutting member from a closed position to an opened or deployed position. The tubular shaft is configured to be disposed over a guidewire, which can have at least one helix spline, flute, slot, thread, or any other suitable structural feature formed on a surface thereof. The cutting member includes at least one tab adapted to engage with the structural feature of the guidewire while the cutting member is disposed in the opened or deployed position, thereby securing the cutting member in the opened or deployed position. The retro guidewire reamer further includes a second mechanism operative to secure the guidewire within the tubular shaft while the cutting member is disposed in the opened or deployed position. 
     In a third aspect, a retro guidewire reamer includes a drill bit having a cannulated shaft with a longitudinal axis, and a cutting member configured as a small hollow segment with a central axis. The cutting member is pivotally, rotatably, or otherwise movably coupled at a distal end of the cannulated shaft such that it can pivot, rotate, or otherwise move between a first position where its central axis is coincident with the longitudinal axis of the shaft, and a second position where its central axis is disposed at an angle to the longitudinal axis of the shaft. The cutting member has a cannulated sidewall with sharpened edges at a forward circumferential end thereof, as well as sharpened edges on an outside surface thereof. 
     In a fourth aspect, a retro guidewire reamer includes a drill bit having a cannulated shaft with a longitudinal axis, and a cutting member configured as a small hollow segment with a central axis. The cutting member is pivotally, rotatably, or otherwise movably coupled adjacent a distal end of the cumulated shaft such that it can pivot, rotate, or otherwise move between a first position where its central axis is coincident with the longitudinal axis of the shaft, and a second position where its central axis is disposed at an angle to the longitudinal axis of the shaft. The cannulated shaft has sharpened edges at a forward circumferential end thereof, and the cutting member has a sidewall with sharpened edges on an outside surface thereof. 
     In a further exemplary mode of operation, a surgeon establishes a path through bone tissue for a guidewire using a guide, places the guidewire along the path, and then removes the guide. With the drill bit&#39;s cannulated shaft and cutting member in the first position (where its central axis is coincident with the longitudinal axis of the shaft) placed over the guidewire, the surgeon uses the retro guidewire reamer to drill a tunnel through the bone over the guidewire, from the outside in, in an antegrade manner. In accordance with the third aspect of the retro guidewire reamer described herein, the surgeon drills the bone tunnel using the sharpened edges at the forward circumferential end of the cutting member, in accordance with the fourth aspect of the retro guidewire reamer described herein, the surgeon drills the bone tunnel using the sharpened edges at the forward circumferential end of the cannulated shaft. Next, the surgeon retracts the guidewire to allow the cutting member to pivot, rotate, or otherwise move from the first position to the second position (where its central axis is disposed at an angle to the shaft&#39;s longitudinal axis). The surgeon then advances the guidewire and locks it to the cannulated shaft, for example, using a lock screw, thereby securing the cutting member in the angled second position. With the cannulated shaft paced over the guidewire and the cutting member in the second position, the surgeon drills a counter bore through the bone over the guidewire in a retrograde manner, using the sharpened edges on the outside surface of the cutting member&#39;s sidewall. 
     Using the disclosed retro guidewire reamers, a surgeon can advantageously deploy a cutting member within a bone joint with a single manual motion. Further, because the cutting member can be deployed within the bone joint by remote activation, the amount of bone joint space required for successful deployment of the cutting member is reduced. Moreover, by providing retro guidewire reamers that include a drill bit having a cannulated shaft, and a cutting member pivotally, rotatably, or otherwise movably coupled to the cannulated shaft and adapted to engage a guidewire at least while in an opened or deployed position, the retro guidewire reamers can be advantageously used with a guidewire for more accurate bone tunnel placement during arthroscopic ligament reconstruction surgery, such as ACL reconstruction surgery. 
     Other features, functions, and aspects of the invention will be evident from the Detailed Description that follows: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments described herein and, together with the Detailed Description, explain these embodiments. In the drawings: 
         FIGS. 1-5   b  illustrate an exemplary mode of operating exemplary retro guidewire reamer, in accordance with the present application; 
         FIGS. 6 a  and 6 b    illustrate the retro guidewire reamer employed in the mode of operation illustrated in  FIGS. 1-5   b;    
         FIG. 7  illustrates various components included in the retro guidewire reamer of  FIGS. 6 a    and  6   b;    
         FIGS. 8 a -8 c    illustrate an exemplary distal tip of the retro guidewire reamer of  FIGS. 6 a    and  6   b;    
         FIGS. 9 a  and 9 b    illustrate an exemplary mechanism or deploying a cutting member included in the retro guidewire reamer of  FIGS. 6 a    and  6   b;    
         FIGS. 10 a -12 b    illustrate various as relating to the operation of the mechanism of  FIGS. 9 a    and  9   b;    
         FIGS. 13 a   - 16  illustrate various aspects relating to the operation and assembly of the retro guidewire reamer of  FIGS. 6 a    and  6   b;    
         FIGS. 17 a -19 b    illustrate a first alternative embodiment of the retro guidewire reamer of  FIGS. 6 a    and  6   b;    
         FIGS. 20 a  and 20 b    illustrate a second alternative embodiment of the retro guidewire reamer of  FIGS. 6 a    and  6   b;    
         FIGS. 21 a  and 21 b    illustrate various components included in the retro guidewire reamer of  FIGS. 20 a    and  20   b;    
         FIGS. 22 a -22 c    illustrate additional views of the retro guidewire reamer of  FIGS. 20 a    and  20   b,  including an exemplary retro lock knob, an exemplary retro lock bushing ring, and an exemplary retro drive bushing; 
         FIGS. 22 d -22 f    illustrate are exemplary distal tip of the retro guidewire reamer of  FIGS. 20 a    and  20   b;    
         FIGS. 23 a -23 m    illustrate an exemplary mode of operating the retro guidewire reamer of  FIGS. 20 a    and  20   b;    
         FIG. 24  illustrates a third alternative embodiment of the retro guidewire reamer of  FIGS. 6 a    and  6   b;    
         FIG. 25  illustrates a detailed view of the retro guidewire reamer of  FIG. 24  in a configuration for drilling a tunnel through bone tissue over a guidewire in an antegrade manner; 
         FIG. 26  illustrates a detailed view of the retro guidewire reamer of  FIG. 24  in a configuration for drilling a counter bore through bone tissue over a guidewire in a retrograde manner; 
         FIGS. 27-31  illustrate an exemplary use of the retro guidewire reamer of  FIG. 24  for creating a tunnel and a counter bore through femoral bone tissue; 
         FIG. 32  illustrates an alternative embodiment of the retro guidewire reamer of  FIG. 24 ; and 
         FIG. 33  is a flow diagram illustrating an exemplary method of operating the retro guidewire reamer of  FIG. 24 . 
     
    
    
     DETAILED DESCRIPTION 
     The disclosures of U.S. Provisional Patent Application No. 61/776,896 filed Mar. 12, 2013 entitled RETRO GUIDEWIRE REAMER, U.S. Provisional Patent Application No. 61/806,578 filed Mar. 27, 2013 entitled RETRO GUIDEWIRE REAMER, and U.S. Provisional Patent Application No. 61/858,800 filed Jul. 26, 2013 entitled RETRO GUIDEWIRE LOCK REAMER, are hereby incorporated herein by reference in their entirety. 
     An exemplary mode of operating an illustrative embodiment of a retro guidewire reamer  1100  is described below with reference to  FIGS. 1-5   b,  in accordance with the present application. As shown in  FIG. 1 , a surgeon establishes a desired path for a guidewire  1114  through femoral bone  1116 . For example, the desired path may be established using a guide (not shown), such as a pinpoint guide or any other suitable guide. The surgeon places the guidewire  1114  along the desired path, and removes the guide. The surgeon can then determine the size of a primary bone tunnel  1112  (see  FIG. 4 ), as well as the size of a counter bore  1110  (see  FIG. 4 ) through the femoral bone  1116  appropriate to fit a replacement tendon graft, using any suitable technique known in the art. As shown in  FIGS. 2 a    and  2   b,  using a drill bit  1102  appropriately sized to create the primary bone tunnel  1112  (e.g., the drill bit  1102  can be a 4.5 mm drill bit or any other suitable drill bit), the surgeon can use a power drill (not shown) to drill the primary bone tunnel  1112  through the femoral bone  1116  over the guidewire  1114  from the outside in. As shown in  FIGS. 3 a    and  3   b,  the surgeon then at least partially retracts the guidewire  1114  and uses a mechanism  1106  to manually open deploy at least one cutting member  1108  (e.g., 1 or 2 such cutting members) within a bone joint  1117  (see also  FIG. 1 ). In one embodiment, the surgeon can push or slide an outer tubular shaft  1104  toward the mechanism  1106  in the direction indicated by a directional arrow  1120  (see  FIG. 3 a   ), thereby causing the mechanism  1106  to open or deploy the cutting member  1108  within the bone joint  1117  in a single manual motion. As shown in  FIG. 4 , the surgeon then uses the power drill with the deployed cutting member  1108  to create the counter bore  1110  through the femoral bone  1116  in a retrograde manner. Once the counter bore  1110  is drilled, the surgeon activates the mechanism  1106  to close the cutting member  1108 , allowing the retro guidewire reamer  1100  to be withdrawn through the primary bone tunnel  1112  created by the drill bit  1102  (see  FIGS. 5 a  and 5 b   ). 
     It is noted that, in the exemplary mode of operation described above, the counter bore  1110  may be drilled along the axis of the primary bone tunnel  1112 , or at a predetermined angle to the primary bone tunnel axis. It is further noted that the retro guidewire reamer  1100  can be cannulated to allow fluid to pass through the tubular shaft during use, thereby clearing out any soft tissue that may potentially block the deployment of the cutting member  1108  within the bone joint  1117 . 
       FIG. 6 a    depicts a side view of the retro guidewire reamer  1100 , as well as a detailed view of the drill bit  1102  and the outer tubular shaft  1104  disposed over the guidewire  1114 .  FIG. 6 b    depicts a further side view of the retro guidewire reamer  1100 , as well as a detailed view of the drill bit  1102 , a tubular shaft  1103 , and the cutting, member  1108  in its fully opened or deployed position. As shown in  FIGS. 6 a    and  6   b,  the retro guidewire reamer  1100  includes the drill bit  1102  having the tubular (cannulated) shaft  1103 , the cutting member  1108  operatively coupled near a distal end of the tubular shaft  1103 , the elongated outer tubular shaft  1104 , and the mechanism  1106  for manually opening or deploying the cutting member  1108 . As discussed herein, the retro guidewire reamer  1100  can be advantageously used with the guidewire  1114  (e.g., a 2.4 mm guidewire, or any other suitable guidewire or guide pin) for more accurate bone tunnel placement during arthroscopic ligament reconstruction surgery, such as anterior cruciate ligament (ACL) reconstruction surgery. 
       FIG. 7  depicts various components of the retro guidewire reamer  100 , including the drill bit  1102 , the tubular shaft  1103 , the cutting member  1108 , the outer tubular shaft  1104 , and the mechanism  1106  for manually opening or deploying the cutting member  1108 .  FIG. 7  further depicts an actuator  1130 , at least one tab  1136  located at a proximal end of the tubular shaft  1104 , a compression spring  1138 , a cam wheel  1140 , at least one drive link  1142 , and a bushing  1144 , all of which are further described below. 
       FIG. 8 a    depicts another detailed view of the drill bit  1102 , the tubular shaft  1103 , the outer tubular shaft  1104 , and the cutting member  1108  in its fully opened or deployed position.  FIG. 8 a    further depicts the actuator  1130  and a lug configuration  1132  for use in conjunction with the mechanism  1106  for opening or deploying the cutting member  1108 . The actuator  1130  and the lug configuration  1132  are also further described below. In addition,  FIG. 8 a    depicts a hole  1134  through the cutting member  1108  that is adapted to accommodate the guidewire  1114  while the cutting member  1108  is in its closed position.  FIG. 8 b    depicts a detailed view of the cutting member  1108  in its closed position. 
       FIG. 8 c    depicts a further detailed view of the drill bit  1102 , the tubular shaft  1103 , and the outer tubular shaft  1104 , as well as an alternative embodiment  1108   a  of the cutting member in its fully deployed position.  FIG. 8 c    further depicts a hole  1134   a  (see also  FIG. 13 c   ) through the cutting member  1108   a  that is adapted to accommodate the guidewire  1114 , thereby securing the cutting member  1108   a  in its deployed position. 
       FIG. 9 a    depicts a detailed view of the outer tubular shaft  1104  and the mechanism  1106 , as well as a detailed view of various components within a mechanism housing  1156  (see also  FIG. 15 ), including the tab  1136  located at the proximal end of the tubular shaft  1104 , the compression spring  1138 , the cam wheel  1140 , and the drive link  1142  interconnecting the cam wheel  1140  and the bushing  1144 .  FIG. 9 b    depicts an exploded view of the various components within the mechanism housing  1156 , further including the actuator  1130  connectable between the cutting member  1108  and the bushing  1144 . 
     As described above with reference to  FIGS. 3 a  and 3 b   , a surgeon can push or slide the outer tubular shaft  1104  toward the mechanism  1106  in the direction indicated by the directional arrow  1120  to cause the mechanism  1106  to open or deploy the cutting member  1108  in a single manual motion. As shown in  FIGS. 10 a  and 10 b   , as the outer tubular shaft  1104  is pushed toward the mechanism  1106 , the tab  1136  comes in contact with the cam wheel  1140 , causing the cam wheel  1140  to rotate in the counter clockwise (CCW) direction and compressing the compression spring  1138  (see  FIG. 10 b   ). As shown in  FIGS. 10 b  and 11 a   , as the cam wheel  1140  rotates in the CCW direction and the compression spring  1138  becomes increasingly compressed, the drive link  1142  moves the bushing  1144  toward the distal end of the tubular shaft  1103 , thereby causing the actuator  1130  to open or deploy the cutting member  1108 . 
     Once the compression spring  1138  is fully compressed and the cutting member  1108  is fully deployed (see  FIG. 11 a   ), the surgeon can gradually release the outer tubular shaft  1104  to allow the compression spring  1138  to push the tubular shaft  1104  against the cutting member  1108  (see  FIG. 11 b   ), preventing the cutting member  1108  from moving from its deployed position. 
     As shown in  FIGS. 12 a    and  12   b,  to move the cutting member  1108  from its opened or deployed position back to its closed position, the surgeon can again push or slide the outer tubular shaft  1104  in the direction indicated by a directional arrow  1122  (see  FIG. 12 b   ) to partially compress the compression spring  1138  as well as partially expose the tubular shaft  1103 , and then push the bushing  1144  toward the mechanism  1106  to rotate the cam wheel  1140  in the clockwise (CW) direction (see  FIG. 12 b   ), thereby causing the actuator  1130  to move the cutting member  1108  to its closed position. 
       FIGS. 13 a   - 16  illustrate various exemplary aspects relating to the operation and assembly of the disclosed retro guidewire reamer  1100 . As shown in  FIG. 13   a,  the lug configuration  1132  (see also  FIG. 8 a   ) includes one or more internal lugs  1132 . 1  on the cutting member  1108  that are configured to slide over corresponding external lugs  1132 . 2  on the tubular shaft  1103 . As shown in  FIG. 13 b   , the actuator  1130  is configured to snap into a side hole  1146  formed in the cutting member  1108 .  FIG. 13 c    depicts the alternative embodiment  1108   a  of the cutting member  1108 , including the holes  1134  and  1134   a  adapted to accommodate the guidewire  1114  while the cutting member  1108   a  is in its closed and opened or deployed positions, respectively. 
     As shown in  FIG. 14   a,  the actuator  1130  is configured to slide into a slot hole  1145  formed in the bushing  1144 . As shown in  FIG. 14 b   , the drive links  1142  are configured slide into holes  1148 ,  1150  formed it the bushing  1144  and the cam wheel  1140 , respectively. As shown in  FIG. 15 , at least one hub  1152  on the cam wheel  1140  is configured to slide into at least one corresponding groove slot  1154  formed in the mechanism housing  1156 . As shown in  FIG. 16 , at least one cap screw  1158  can be employed to secure a housing cover  1160  to the mechanism housing  1156 . Further, at least one button head screw  1162  can be employed to secure the cam wheel  1140 , as well as the various components attached to the cam wheel  1140 , within the mechanism housing  1156 . In addition, at least one set screw  1164  can be employed to secure the mechanism housing  1156  to a portion of a drill  1166 . 
       FIGS. 17 a -19 b    depict various exemplary aspects relating to an alternative embodiment  11700  of the retro guidewire reamer  1100 . As shown in  FIG. 17 a   , the retro guidewire reamer  11700  includes a drill bit  11702 , an elongated outer tubular shaft  11704 , and one or more cutting members  11708  (e.g., 1 or 2 cutting members). Like the retro guidewire reamer  1100 , the retro guidewire reamer  11700  can be advantageously used with a guidewire  11714  (e.g., a 2.4 mm guidewire, or any other suitable guidewire or guide pin) for more accurate bone tunnel placement during arthroscopic ligament reconstruction surgery, such as ACL reconstruction surgery. 
     As shown in  FIGS. 19 a    and  19   b,  the cutting members  11708  are attached to the outer tubular shaft  11704  by a ball and socket connection  11770 ,  11772 . The cutting members  11708  are configured to move axially with the outer tubular shaft  11704 , and to rotate via the ball and socket connection  11770 ,  11772 . The ball and socket connection  11770 ,  11772  is integrated into the cutting members  11708  and the outer tubular shaft  11704 , respectively, advantageously providing a “pin-less” design. Each “male” ball (see reference numeral  11770 ) is integrated into one of the cutting members  11708 , and each “female” socket (see reference numeral  11772 ) is integrated into the outer tubular shaft  11704 . Further embodiments of the retro guidewire reamer  11700  may employ at least one pin (not shown) to connect the cutting members  11708  to the outer tubular shaft  11704 . 
     During an arthroscopic procedure, a surgeon can push or slide the outer tubular shaft  11704  toward the drill bit  11702  to cause the cutting members  11708  to impinge against a stop on the drill bit  11702  and to rotate outward, thereby opening or deploying the cutting members  11708  in a single manual motion. The outer tubular shaft  11704  disposed against the drill bit  11702  prevents the cutting members  11708  from moving from their opened or deployed positions ( FIGS. 17 b  and 17 d   ). The surgeon can subsequently push the outer tubular shaft  11704  away from the drill bit  11702  to cause the cutting members  11708  to rotate inward back to their closed positions (see  FIGS. 17 a  and 17 c   ). 
     To facilitate assembly of the retro guidewire reamer  1700 , an assembly slot  11774  (see  FIG. 18 ) can be provided to allow the cutting members  11708  to be fully inserted into the inner diameter of the retro guidewire reamer  11700 , and to allow the outer tubular shaft  11704  to be advanced to the proper location for alignment of the ball and socket connection  11770 ,  11772 . Once the female socket  11772  is aligned with the assembly slot  11774 , the cutting members  11708  can be rotated outward until the male ball  11770  resides within the female socket  11772 . At that point, the outer tubular shaft  11704  with the cutting members  11708  attached thereto can be advanced distally beyond the assembly slot  11774 . 
       FIGS. 20 a  and 20 b    depict a further illustrative embodiment of an exemplary retro guidewire reamer  2100 , in accordance with the present application. As shown in  FIGS. 20 a    and  20   b,  the retro guidewire reamer  2100  includes a drill bit  2102  having a tubular (cannulated) shaft  2103 , at least one cutting member  2108  operatively coupled near a distal end of the tubular shaft  2103 , an elongated outer tubular shaft  2104 , a retro drive bushing  2172 , a retro lock knob  2174 , a retro lock bushing ring  2176 , and a depth slide  2180 .  FIG. 20 a    further depicts a detailed view of the drill bit  2102 , the tubular shaft  2103 , and the outer tubular shaft  2104  disposed over a guidewire  2114 .  FIG. 20 b    further depicts a detailed view of the drill bit  2102 , the tubular shaft  2103 , the outer tubular shaft  2104 , and the cutting member  2108  in its fully opened or deployed position. The retro guidewire reamer  2100  can be advantageously used with the guidewire  2114  (e.g., a 2.4 mm guidewire, or any other suitable guidewire or guide pin) for more accurate bone tunnel placement during arthroscopic ligament reconstruction surgery, such as AOL reconstruction surgery. 
       FIGS. 21 a  and 21 b    depict various components of the disclosed retro guidewire reamer  2100 , including the drill bit  2102 , the tubular shaft  2103 , the cutting member&#39; 2108 , the outer tubular shaft  2104 , the retro drive bushing  2172 , the depth slide  2180 , a retrograde actuator  2130 , the retro lock knob  2174 , and the retro lock bushing ring  2176 . The retro lock knob  2174  can have a pin or projection configured to engage a hole  2178  (see  FIG. 21 b   ) in the tubular shaft  2103 , and to make contact with the guidewire  2114  disposed in the tubular shaft  2103 . During use, the retro drive bushing  2172  and the retrograde actuator  2130  cooperate to move the cutting member  2108  from a closed position to its opened or deployed position, and vice versa. Further, during use, the retro lock knob  2174  and the retro lock bushing ring  2176  cooperate to secure the guidewire  2114  within the tubular shaft  2103 , and to stabilize and strengthen the guidewire  2114  the tubular shaft  2103 , and the cutting member  2108  as a unit, as further described herein. 
       FIGS. 22 a -22 c    depict additional views of the retro guidewire reamer  2100  of  FIGS. 20 a  and 20 b   , including the drill bit  2102 , the tubular shaft  2103 , the cutting member  2108 , the outer tubular shaft  2104 , the retro lock knob  2174 , the retro lock bushing ring  2176 , and the retro drive bushing  2172 . As shown in  FIG. 22 a   , the tubular shaft  2103  is configured to be disposed over the guidewire  2114 . As shown in  FIG. 22 b   , once the guidewire  2114  is at least partially retracted within the tubular shaft  2103 , the retro drive bushing  2172  can be moved along the cuter tubular shaft  2104  toward the distal end of the tubular shaft  2103 , causing the retrograde actuator  2130  to move the cutting member  2108  to its deployed position. 
     As shown in  FIG. 22   c,  while the cutting member  2108  is being moved to its fully deployed position, the guidewire  2114  can twist within the tubular shaft  2103  and become engaged with and/or locked into the cutting member  2108 . In one embodiment, the guidewire  2114  can include at least one helix spline  2170  (see  FIGS. 20   a,    22   a,  and  22   c - 22   e ), or any other suitable structural feature (e.g., a flute, a slot, a thread), configured to engage with and/or lock into the cutting member  2108  as the guidewire  2114  twists (or is twisted by a user) within the tubular shaft  2103 . Once the cutting member  2108  is in its fully deployed position, the retro lock knob  2174  can be rotated (e.g., clockwise) to cause the pin or projection to engage the hole  2178  and make contact with the guidewire  2114  disposed in the tubular shaft  2103 , thereby securing, stabilizing, and strengthening the guidewire  2114 , the tubular shaft  2103 , and the cutting member  2108  as a unit. 
       FIG. 22 d    depicts a detailed view of the drill bit  2102 , the tubular shaft  2103 , the outer tubular shaft  2104 , and the cutting member  2108  in its fully deployed position. While the cutting member  2108  is in its fully deployed position, the helix spline  2170  (or any other suitable structural feature of the guidewire  2114 ) can engage with and/or lock into the cutting member  2108 . In one embodiment, the helix spline  2170  can engage with and/or lock into a tab  2182  formed in the cutting member  2108 , as shown in  FIG. 22 e   .  FIG. 22 d    further depicts the retrograde actuator  2130 , as well as a lug configuration  2132 , for use in conjunction with the retro drive bushing  2172  for deploying the cutting member  2108 .  FIG. 22 d    also depicts a hole  2134  through the cutting member  2108  that is adapted to accommodate the guidewire  2114  while the cutting member  2108  is in its closed position.  FIG. 22 f    depicts a detailed view of the cutting member  2108  in its closed position, a plurality of flutes  2102   a  formed on the drill bit  2102 , and a hole  2147  through the cutting member  2108  that is adapted to accommodate the guidewire  2114  while the cutting member  2108  is in its deployed (or opened) position. In one embodiment, the hole  2147  through the cutting member  2108  is adapted to receive the helix spline  2170  of the guidewire  2114 , which, in conjunction with the retro lock knob  2174 , can provide further support and stabilization to the cutting member  2108  in its deployed position, while securing the guidewire  2114 , the tubular shaft  2103 , and the cutting member  2108  as a unit. 
       FIGS. 23 a -23 m    illustrate an exemplary mode of operating the retro guidewire reamer  2100  of  FIGS. 20 a    and  20   b.  In this mode of operation, a surgeon can use a guide (not shown) to establish a desired path for the guidewire  2114  through femoral bone  2116  (see  FIG. 23 a   ). For example, the guide may be a pinpoint guide, or any other suitable guide. The surgeon places the guidewire  2114  along the desired path and removes the guide. The surgeon then obtains a measure straw  2115  that is substantially the same length as the guidewire  2114  (see  FIG. 23 b   ). The surgeon places the measure straw  2115  against the femoral bone  2116 , and cuts the measure straw  2115 , as desired and/or required, at its proximal end (see  FIG. 23 c   ). 
     Next, the surgeon determines the size of a primary bone tunnel  2112  (see  FIGS. 23 k -23 m   ), as well as the size of a counter bore  2110  (see  FIGS. 23 k -23 m   ) through the femoral bone  2116  appropriate to fit a replacement tendon graft, using any suitable technique known in the art. Using the drill bit  2102  appropriately sized to create the primary bone tunnel  2112  (e.g., the drill bit  2102  can be a 4.5 mm drill bit or any other suitable drill bit), the surgeon uses a power drill (not shown) to drill the bone tunnel  2112  through the femoral bone  2116  over the guidewire  2114  from the outside in (see  FIGS. 23 d  and 23 e   ). The surgeon then at least partially retracts the guidewire  2114 , and moves the retro drive bushing  2172  along the outer tubular shaft  2104  toward the distal end of the tubular shaft  2103 , causing the retrograde actuator  2130  to move the cutting member  2108  to its deployed position (see  FIGS. 23 f  and 23 g   ). While the cutting member  2108  is being moved to its fully deployed position, the guidewire  2114  twists within the tubular shaft  2103  as the helix spline  2170  becomes engaged with and/or locks into the tab  2182  (see  FIG. 22 e   ) of the cutting member  2108  (see  FIG. 23 h   ). Once the cutting member  2108  is in its fully deployed position, the surgeon rotates (e.g., clockwise) the retro lock knob  2174  to secure and stabilize the guidewire  2114 , the tubular shaft  2103 , and the cutting member  2108  together as a unit (see  FIG. 23 i   ). 
     Next, the surgeon places the depth slide  2180  against a lateral side of the femoral bone  2116  to determine the length of the counter bore  2110  (see  FIG. 23 j   ). Alternatively, instead of the depth slide  2180 , a depth straw (not shown) may be employed for determining the length of the counter bore  2110 . The surgeon then uses the power drill with the deployed cutting member  2108  to create the counter bore  2110  through the femoral bone  2116  in a retrograde manner (see  FIG. 23 k   ). Once the counter bore  2110  is drilled, the surgeon rotates (e.g., counter clockwise) the retro lock knob  2174  to release the guidewire  2114  from within the tubular shaft  2103 , untwists the guidewire  2114  within the tubular shaft  2103  to disengage the helix spline  2170  from the cutting member  2108 , and moves the retro drive bushing  2172  along the outer tubular shaft  2104  toward the retro lock knob  2174  to cause the retrograde actuator  2130  to move the cutting member  2108  from its deployed (opened) position to its closed position, allowing the retro guidewire reamer  2100  to be withdrawn through the primary bone tunnel  2112  created by the drill bit  2102  (see  FIGS. 23 l  and 23 m   ). 
     It is noted that, in the exemplary mode of operation described above, the counter bore  2110  may be drilled along the axis of the primary bone tunnel  2112 , or at a predetermined angle to the primary bone tunnel axis. It is further noted that the retro guidewire reamer  2100  is cannulated to allow fluid to pass through the tubular shaft  2103  and/or the outer tubular shaft  2104  during use, thereby clearing out any soft tissue that may potentially block the deployment of the cutting member  2108 . 
     Having described the above exemplary embodiment of the retro guidewire reamer  2100 , other alternative embodiments or variations may be made. For example, the bone tunnel  2112  may be drilled through the femoral bone  2116  over the guidewire  2114  with the distal tip of the retro guidewire reamer  2100  enclosed. The counter bore  2110  may then be drilled after pivoting, rotating, or otherwise moving the cutting member  2108  to its deployed position. 
       FIG. 24  depicts another illustrative embodiment of an exemplary retro guidewire reamer  3100  for creating tunnels through bone tissue during arthroscopic ligament reconstruction surgery, in accordance with the present application. As shown in  FIG. 24 , the retro guidewire reamer  3100  includes a drill bit  3101  having a tubular (cannulated) shaft  3102 , and a cutting member  3104  configured as a small hollow segment. The cutting member  3104  is pivotally, rotatably, or otherwise movably coupled at a distal end of the cannulated shaft  3102 . The retro guidewire reamer  3100  is operative to drill a tunnel through bone over a guidewire  3106  in an antegrade manner, and to drill a counter bore through the bone over the guidewire  3106  in a retrograde manner. The retro guidewire reamer  3100  further includes a lock screw  3108  for locking the guidewire  3106  in place, as needed, during use. As further shown in  FIG. 24 , the guidewire  3106  can have a pointed distal end  3106   a.    
       FIG. 25  depicts a detailed view of the retro guidewire reamer  3100  of  FIG. 24  in a configuration for drilling a tunnel through bone over the guidewire  3106  in an antegrade manner. As shown in  FIG. 25 , the cutting member  3104  is pivotally coupled, by a pair of pivot pins  3105   a  at a distal end of the cannulated shaft  3102  in a first position where its central axis  3107  is coincident with the longitudinal axis  3109  of the shaft  3102 . The cutting member  3104  has a tubular (cannulated) sidewall  3111  with sharpened edges  3104 . 1  at a forward circumferential end thereof. 
       FIG. 26  is another detailed view of the retro guidewire reamer  3100  of  FIG. 24  in a configuration for drilling a counter bore through bone over the guidewire  3106  in a retrograde manner. As shown in  FIG. 26 , the cutting member  3104  is pivotally, rotatably, or otherwise movably coupled at the distal end of the cannulated shaft  3102  such that it can pivot, rotate, or otherwise move from the first position where its central axis  3107  was coincident with the longitudinal axis  3109  of the shaft  3102  (see  FIG. 25 ), to a second position where its central axis  3107  is disposed at an angle θ to the longitudinal axis  3109  of the shaft  3102 . The cannulated sidewall  3111  of the cutting member  3104  also has sharpened edges  3104 . 2  on an outside surface thereof. 
     The disclosed retro guidewire reamer  3100  will be further understood with reference to the following illustrative example, and  FIGS. 27-31 . In this example, the retro guidewire reamer  3100  is employed in an arthroscopic surgical procedure to drill a tunnel  3402  (see  FIG. 27 ) through femoral bone  3400  over the guidewire  3106  in an antegrade manner, and to drill a counter bore  3802  (see  FIG. 30 ) through the femoral bone  3400  over the guidewire  3106  in a retrograde manner. First, a surgeon establishes a desired path  3401  through the femoral bone  3400  for the guidewire  3106  using a guide (not shown), places the guidewire  3106  along the path  3401 , and removes the guide. With the cannulated shaft  3102  and the cutting member  3104  in the first position (see  FIG. 25 ) placed over the guidewire  3106 , the surgeon uses the retro guidewire reamer  3100  to drill the tunnel  3402  through the femoral bone  3400  over the guidewire  3106  from the outside in, in an antegrade manner. In this example, the surgeon drills the bone tunnel  3402  using the sharpened edges  3104 . 1  at the forward circumferential end of the cutting member  3104 . 
     Next, the surgeon retracts the guidewire  3106 , causing its pointed distal end  3106   a  to be withdrawn inside the cannulated shaft  3102  so that it is no longer engaged with the cutting member  3104  and blocking or otherwise preventing the cutting member  3104  from movement (see  FIG. 28 ). Such retraction of the guidewire  3106  allows the cutting member  3104  to pivot, rotate, or otherwise move from the first posit on where its central axis  3107  was coincident with the shafts longitudinal axis  3109  (see  FIG. 25 ), to the second position where its central axis  3107  is disposed at the angle θ to the shaft&#39;s longitudinal axis  3109  (see  FIGS. 26 and 29 ). The surgeon then advances the guidewire  3106 , causing pointed distal end  3106   a  to pass through the cannulated shaft  3102  to a position beyond the pivot coupling of the cutting member  3104  and the shaft  3102 , and to block or otherwise prevent any further movement of the cutting member  3104  (see  FIG. 29 ). The surgeon can now lock the guidewire  3106  to the cannulated shaft  3102  using the lock screw  3108  (see  FIG. 31 ), thereby securing the cutting member  3104  in the angled second position. With the cannulated shaft  3102  placed over the guidewire  3106  and the cutting member  3104  in the second position, the surgeon can drill the counter bore  3802  (see  FIG. 30 ) through the femoral bone  3400  over the guidewire  3106  in a retrograde manner, using the sharpened edges  3104 . 2  on the outside surface of the cutting member&#39;s sidewall  3111 . 
     Having described the above exemplary embodiment of the disclosed retro guidewire reamer  3100 , other alternative embodiments or variations may be made. For example, it was described herein that a surgeon can drill a bone tunnel over the guidewire  3106  in an antegrade manner using the sharpened edges  3104 . 1  at the forward circumferential end of the cutting member  3104 , and drill a counter bore through the bone over the guidewire  3106  in a retrograde manner using the sharpened edges  3104 . 2  on the outside surface of the cutting member&#39;s sidewall  3111 . In an alternative embodiment  3900  of the retro guidewire reamer (see  FIG. 32 ) sharpened edges at a forward circumferential end of a tubular (cannulated) shaft  3902  can be used to drill a bone tunnel over a guidewire in an antegrade manner. 
       FIG. 32  depicts the retro guidewire reamer  3900 , which includes a drill bit having the cannulated shaft  3902  with a longitudinal axis  3909 , and a cutting member  3904  configured as a small hollow segment with a central axis  3907 . The cutting member  3904  is pivotally coupled by pivot pins  3905  adjacent a distal end of the cannulated shaft  3902  such that it can rotate from a first position where its central axis  3907  is coincident with the longitudinal axis  3909  of the shaft  3902 , to a second position where its central axis  3907  is disposed at an angle γ to the longitudinal axis  3909  of the shaft  3902 . The cannulated shaft  3902  has sharpened edges  3902 . 1  at a forward circumferential end thereof for drilling a bone tunnel over a guidewire  3906  in an antegrade manner, and the cutting member  3904  has a sidewall with sharpened edges  3904 . 1  on an outside surface thereof for drilling, a counter bore over the guidewire  3906  in a retrograde manner. 
     It is noted that, after the cutting member  3904  is rotated to the second position where its central axis  3907  is disposed at the angle γ to the longitudinal axis  3909  of the shaft  3902 , a surgeon can advance the guidewire  3906 , causing its pointed distal end  3906   a  to pass through the cannulated shaft  3902  to a position beyond the pivot coupling of the cutting member  3904  and the shaft  3902 , and to block or otherwise prevent any further rotation or movement of the cutting member  3904  (see  FIG. 32 ). An opening is provided in the portion of the cutting member&#39;s sidewall disposed within the cannulated shaft  3902  to allow the pointed distal end  3906   a  of the guidewire  3906  to pass through the cutting member  3904  when it is disposed in the second position (see  FIG. 32 ). To allow the cutting member  3904  to pivot, rotate, or otherwise move from the second position back to the first position, where its central axis  3997  is coincident with the longitudinal axis  3909  of the shaft, the surgeon can retract the guidewire  3906 , causing its pointed distal end  3906   a  to be withdrawn inside the cannulated shaft  3902  so that it is no longer engaged with the cutting member  3904  and blocking or otherwise preventing the cutting member  3904  from rotation or movement. 
     A method of operating the disclosed retro guidewire reamers  3100 ,  3900  for creating tunnels through bone tissue during arthroscopic ligament reconstruction surgery is described below with reference to  FIG. 33 . As depicted in block  31002 , a retro guidewire reamer is provided including a drill bit having a cannulated shaft, and a cutting member configured as a small hollow segment, in which the cutting member is pivotally, rotatably or otherwise movably coupled at a distal end of the cannulated shaft, allowing the cutting member to pivot, rotate, or otherwise move from a first position where its central axis is coincident with a longitudinal axis the shaft, to a second position where its central axis is disposed at an angle to the longitudinal of the shaft. As depicted in block  31004 , with the cutting member disposed in the first position, a tunnel is drilled through the bone over a guidewire in an antegrade manner. As depicted in block  31006 , with the cutting member disposed in the second position, a counter bore is drilled through the bone over the guidewire in a retrograde manner. 
     It will be appreciated by those of ordinary skill in the art that modifications to and variations of the above-described apparatus and methods may be made without departing from the inventive concepts disclosed herein. Accordingly, the invention should not be viewed as limited except as by the scope and spirit of the appended claims.