Abstract:
A surgical drill for providing holes at an angle for use in repair and replacement of the ACL is disclosed, generally comprising a drill guide having a head that is angularly adjustable with respect to a body, a flexible guide pin and a flexible drill. The adjustable head of the drill guide allows a surgeon to drill a hole in the femur at an angle to a tunnel provided in the tibia. Because the surgeon can access the femur via the hole in the tibia, the surgical drill of the present invention obviates the need for a second hole in the tissue and also makes placement of femur hole more precise for securement of the ligament or tendon graft within the hole.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a divisional of pending U.S. patent application Ser. No. 12/337,284, filed on Dec. 17, 2008, which claims the benefit under 35 U.S.C. §119 (e) of the U.S. Provisional Patent Application No. 61/014,188 filed on Dec. 17, 2007. The content of all prior applications is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a surgical drill. More specifically, the invention relates to a surgical drill for providing a second hole in a bone at an angle relative to a first hole drilled in a bone. 
       BACKGROUND OF THE INVENTION 
       [0003]    Damage to ligaments, such as anterior cruciate ligaments (ACL) and the posterior cruciate ligaments (PCL), cartilage, and tendons has become a relatively common occurrence and often requires surgical repair. Often, the ACL or the PCL is ruptured or torn as a result of physical activity and, consequently, various surgical procedures have been developed for replacing or reconstructing these ligaments. 
         [0004]    The knee joint is often repaired by substituting a harvested or synthetic replacement ligament for the damaged one. Commonly, a substitute ligament or graft is inserted into tunnels reamed in the femur and tibia bones. Once anchored in place, the graft ligament is able to cooperate with the surrounding bone and tissues and thereby perform the functions of the damaged ACL or PCL. One problem associated with this technique is locating the proper position and angle for drilling the tunnel in the femur (femoral tunnel). Several methods have been developed for determining the location for drilling the femoral tunnel. 
         [0005]    One such method is to insert a drill guide and guide pin through the incision and tunnel in the tibia and into the femur. In order to accurately shoot a guide pin for femoral tunnel preparation, most surgeons use an “over the top” drill guide, as shown in U.S. Pat. No. 5,320,115 to Kenna and U.S. Pat. No. 5,320,626 to Schmieding. This type of drill guide references the back wall of the femoral notch to deliver the guide pin a certain distance in millimeters from the back wall. The distance desired is chosen by the surgeon depending on the diameter of the ACL graft to be used. A reamer will be used over the guide pin to create the femoral tunnel, and  2  mm of back wall or less should be present behind the tunnel. It is undesirable to ream through the back wall and in many cases the chosen fixation method will not work if this occurs. For example, if an 8 mm ACL graft is to be used then a 6 mm over the top guide is selected. This will place the guide pin 6 mm from the back wall. When an 8 mm reamer is used over the guide pin, then 2 mm of back wall will remain. 
         [0006]    Traditionally the over the top guide is placed through the drilled tibial tunnel to position the guide easily on the back wall. When the tibial tunnel is drilled properly, however, the over the top guide is fairly vertical in the notch in the frontal plane because the placement of the guide is dictated by the angle of the tibial tunnel. Recent studies are indicating that a more lateral femoral tunnel placement is desirable. Yet, this angle is difficult to reach when using a traditional over the top guide in the tibial tunnel, so some surgeons are recommending using a second low medial portal to place the over the top guide. This allows for more lateral positioning in the AP plane, but, consequently, starting more superior decreases the angle of pin placement in the lateral plane, increasing the chance of reaming through the back wall of the femur. 
         [0007]    While the medial portal can be used, and has the advantage of allowing for a more lateral femoral tunnel, it has several disadvantages that make it undesirable. Notably, using the medial portal involves making a second incision in the tissue, which results in unnecessary fluid loss and an additional scar. Furthermore, in order to use the medial portal, hyperflexion of the knee must be performed which is sometimes difficult to do. Also, while some have probably begun designing new instruments and techniques for those who are comfortable using the medial portal, most surgeons are most familiar and most comfortable with using the tibial tunnel as a reference for placing the femoral tunnel. These surgeons are not likely to drastically change the technique they are comfortable with. Last, as stated above, using the medial portal increases the chance of reaming through the back wall of the femur which can make it difficult or impossible to properly secure the graft ligament. Using the tibial tunnel as a reference puts the guide pin in a safe trajectory so that the back wall will not be violated during reaming. 
         [0008]    It is therefore desirable to have a surgical drill which uses the tibial tunnel as a reference for placing the femoral tunnel. In addition, it is desirable to have a drill guide which allows for more lateral femoral tunnel placement. 
       SUMMARY OF THE INVENTION 
       [0009]    Accordingly, it is an object of the present invention to provide a method for drilling a tunnel in a human femur at an angle relative to a tunnel drilled in the tibia. 
         [0010]    It is a further object of the present invention to provide a surgical drill which allows a user to drill a tunnel in a femur at an angle to a tunnel in the tibia. 
         [0011]    It is yet a further object of the present invention to provide a drill guide having a head that is angularly adjustable relative to the body, thus allowing a user to drill a tunnel in a femur at an angle to a tunnel in the tibia. 
         [0012]    These and other objects and advantages are achieved by providing a surgical drill comprising a drill guide, a guide pin, which may be made of a flexible material, and a drill, which may also be flexible. The drill guide comprises a body and a head rotatably mounted to the body at a pivot point which allows a user to drill along an axis x and thereafter also along an axis y. The drill guide may further comprise a longitudinal channel passing through said body and into the head for releasably accepting the guide pin. 
         [0013]    In addition, the drill guide may also comprise an actuator, comprising a rod, a screw having external threads, and a knob threadably connected to the screw, for adjusting the angular orientation of the head with respect to the body. At a distal end, the rod may be connected to the head of the drill guide and may be connected at a proximal end to the screw. The rod may pass through the body of the drill guide. Rotation of the knob may cause the screw and the rod to advance in a distal direction or retract in a proximal direction, further causing the head to rotate about a pivot point. To allow for rotation of the head, the rod may be connected to the head at a point radially spaced from the pivot point. In one embodiment, clockwise rotation of said knob causes the screw and the rod to advance in a distal direction, further causing the head to rotate clockwise about a pivot point. In another embodiment, counter-clockwise rotation of the knob causes the screw and the rod to retract in a proximal direction, further causing the head to rotate counter-clockwise about a pivot point. 
         [0014]    A drill guide comprising a body, a head rotatably mounted to said body at a pivot point for permitting drilling along an axis x and thereafter also along an axis y, and an actuator for adjusting the angular orientation of the head with respect to the body is also provided. In one embodiment, the drill guide further comprises a longitudinal channel passing through said body and into said head for releasably accepting a guide pin. In another embodiment, the drill guide further comprises a handle located adjacent to the body. In yet another embodiment, the actuator comprises a rod, a screw, and a knob threadably connected to the screw, for adjusting the angular orientation of the head with respect to the body. 
         [0015]    A method of drilling a hole in a human femur is also provided, comprising the steps of: providing a hole in a human tibia along an axis x; providing a surgical drill comprising a guide pin, a drill guide for accepting said guide pin, and a drill, wherein the drill guide allows a user to drill a hole in a human femur at an angle relative to the hole in the tibia; inserting the drill guide into the hole in the tibia; inserting the guide pin into the drill guide until the pin comes into contact with and is anchored to the femur; removing the drill guide from the hole in the tibia while leaving the guide pin anchored to the femur; inserting the drill around the anchored guide pin until the drill comes into contact with the femur; drilling a hole in said femur along an axis y, at an angle relative to axis x. 
         [0016]    In one embodiment, the drill guide comprises a body and a head rotatably mounted to the body. The method may also comprise the step of adjusting the angle of the drill guide head with respect to the body until a desired angle is achieved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of an embodiment of the drill guide as used with the surgical drill of the present invention. 
           [0018]      FIG. 2  is a side view of an embodiment of the guide pin as used with the surgical drill of the present invention. 
           [0019]      FIG. 3  is a side view of an embodiment of the flexible drill as used with the surgical drill of the present invention. 
           [0020]      FIG. 4  is a side view of an embodiment of the drill guide as used with the surgical drill of the present invention. 
           [0021]      FIG. 5  is a side sectional view of an embodiment of the drill guide as used with the surgical drill of the present invention. 
           [0022]      FIG. 6(   a ) is a side view of an embodiment of the drill guide as used with the surgical drill of the present invention, showing the head aligned along an axis x. 
           [0023]      FIG. 6(   b ) is a side view of an embodiment of the drill guide as used with the surgical drill of the present invention, showing the head aligned along an axis y, at an angle A to axis x. 
           [0024]      FIG. 7  is a view of an embodiment of the drill guide and guide pin, as used with the surgical drill of the present invention, being used in a human knee. 
           [0025]      FIG. 8  is a view of an embodiment of the drill guide and guide pin, as used with the surgical drill of the present invention, being used in a human knee. 
           [0026]      FIG. 9  is a view of an embodiment of the guide pin, as used with the surgical drill of the present invention, anchored in a human femur bone. 
           [0027]      FIG. 10  is a view of an embodiment of the flexible drill and guide pin, as used with the surgical drill of the present invention, being used to drill a tunnel in a human femur bone. 
           [0028]      FIG. 11  is a view of a femoral tunnel placed by the surgical drill of the present invention, at an angle relative to a tibial tunnel. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]      FIGS. 1-3  depict the surgical drill in accordance with the present invention, which comprises drill guide  20 , pin  60 , and flexible drill  70 . The surgical drill of the present invention provides a second hole along an axis y that may be at an angle relative to a first hole along an axis x. More specifically, particularly in view of the problems associated with the prior art described herein, the surgeon can drill a tunnel in the femur at an angle relative to a tunnel in the tibia. Because the surgeon can access the femur via the tunnel in the tibia, the surgical drill of the present invention obviates the need for a second hole in the tissue and also makes placement of femoral tunnel  90  more precise for securement of the ligament or tendon graft within the tunnel. As discussed in the prior art, placement of the femoral tunnel was problematic and poor placement may lead to improperly secured ligaments or tendons. 
         [0030]    Referencing  FIG. 1 , drill guide  20  of the surgical drill comprises a head  22 , rotatably connected to a body  24 , an actuator assembly  26 , a handle  28 , and an internal longitudinal channel  30  having an opening  32  for releasably accepting guide pin  60 . The channel  30  extends through the body  24  and into the head  22 . As shown in more detail in  FIG. 5 , actuator assembly  26  comprises a rod  34  having a distal end  36  and a proximal end  38 , a screw  40  having external threads  42 , and a knob  44  threadably connected to the screw  40 . The distal end  36  of the rod  34  is connected to the head and the proximal end  38  is connected to the screw  40 . The actuator assembly is contained within a housing  46 . 
         [0031]    To adjust the angle A of head  22  relative to body  24 , a user rotates knob  44 . Due to their threaded connection, this rotation of the knob  44  translates into linear movement of screw  40  and rod  34 . To provide rotation of the head  22  with actuation of the rod  34 , the rod is connected to the head at a point radially spaced apart from the pivot point  48  where the head  22  connects to the body  24 . In the present embodiment, clockwise rotation of the knob  44  causes the rod  34  to advance towards the distal end  36 , which causes the head  22  to accordingly rotate clockwise. Counter-clockwise rotation of the knob  44  causes the rod  34  to retract towards the proximal end  38 , which, in turn, causes the head to rotate counter-clockwise. In a preferred embodiment, the ratio of rotation of the knob to angular rotation of the head is 18:1, meaning that for every 18 degrees of rotation of knob  44 , angle A will change by 1 degree. Thus, to adjust angle A by 15 degrees, the knob  44  must be rotated by 270 degrees. This ratio provides the user with acceptable precision for adjustment of angle A, yet allows full range of motion of the head with only one turning motion. Other ratios are contemplated herein and could be easily adjusted by one having skill in the art. In addition, other mechanisms, such as a trigger, are contemplated for adjusting the angular orientation of the head  22  with respect to the body  24 . 
         [0032]    Guide pin  60  of the surgical drill, depicted in  FIG. 2 , has a distal end  62  and a proximal end  64 . Pin head  66 , located at the distal end  62 , is pointed in the present embodiment so that it may penetrate a patient&#39;s femur bone. In an alternative embodiment, distal end  62  may be formed as a screw so that it may be screwed into a patient&#39;s femur bone. As shown in  FIGS. 6(   a ) and  6 ( b ), angular adjustment of head  22  causes an angular displacement A of pin  60  with respect to the body  24 . Thus, guide pin  60  is made of a flexible material such that it can bend when the angle A of the head  22  of the drill guide  20  is adjusted. However, the material must be rigid enough so that it will maintain its shape when the drill  70  is passed over the guide pin  60 . 
         [0033]    Drill  70  of the surgical drill, depicted in  FIG. 3 , has a distal end  72  and a proximal end  74 . Located at the distal end  72  is the drill bit  76  and flexible portion  78 . An internal channel  80  that runs the length of the drill  70  is also provided so that the drill  70  may be slid over the guide pin  60 . Flexible portion  78  allows the drill  70  to pass over the guide pin  60  in a bent shape. 
         [0034]    In operation, known methods are used to create a tibial tunnel  86  in the tibia  82  that extends towards the femur  84 . Typically, a drill guide specifically designed for drilling tibial tunnels is placed against the tissue. A guide pin is then inserted into the drill guide for piercing the tissue to create a first tissue hole. Once the guide pin is anchored in the tibia, the drill guide is removed and a standard drill is slid over the drill guide and is used to create tibial tunnel  86 . 
         [0035]    Referring now to  FIGS. 7 and 8 , to create a femoral tunnel  90 , guide pin  60  is inserted into opening  32  of drill guide  20 . Together, the drill guide  20  and guide pin  60  are inserted into the tibial tunnel  86  until the guide  20  is in close proximity to the femur and the head  22  has passed through tibial tunnel  86 . The user, typically a surgeon, then rotates knob  44  to adjust the angle A of head  22 . Because the body  24  of the drill guide  20  remains stationary within the tibial tunnel  86  while the head  22  is free to rotate with respect to the body  24 , the drill guide of the present invention allows the user to drill a second (femur) tunnel at an angle to the first (tibia) tunnel. Once a desired angle is achieved, pin  60  is pushed further through the internal channel  30  until pin head  66  passes through the now angled head  22  and in comes in contact with femur  84 . Once in contact with femur  84 , further force is needed to anchor pin head  66  within femur  84 . In some cases, this further force is achieved by drilling the pin through drill guide  20 . 
         [0036]    Notably, the drill guide of the present invention is versatile in that it provides a surgeon with a large range of angles at which to place the femoral tunnel with respect to the tibial tunnel. Thus, the surgeon is not limited to either drilling a straight femoral tunnel or to drilling the femoral tunnel at a single, fixed angle, as is the case with the straight or fixed angle drill guides of the prior art. 
         [0037]    Drill guide  20  is then removed by sliding it away from the femur  84  back through the tibial tunnel  86  and away from the patient. As shown in  FIG. 9 , guide pin  60  is left in place anchored to femur  84 . Flexible drill  70  is then inserted around pin  60  toward the patient by passing pin  60  through internal channel  80  of flexible drill  70 . The diameter of flexible drill  70  should be the same as or smaller than the diameter of tibia tunnel  86  such that flexible drill  70  passes through tibia tunnel  86  and toward femur  84 . It should be understood that pin  60  acts as a guide for leading flexible drill  70  toward femur  84  at the angle set by pin  60  and head  22 . Once in contact with femur  84 , flexible drill  70  drills femoral tunnel  90  by being rotated about with a standard driller, or machine for rotating a drill bit. 
         [0038]    After femoral tunnel  90  is drilled, flexible drill  70  and guide pin  60  are removed from the patient. As shown in  FIG. 11 , resulting is a femoral tunnel placed at an angle with respect to the tibial tunnel. 
         [0039]    In another embodiment, flexible pin  60  and flexible drill  70  are used to drill both tibial tunnel  86  and femoral tunnel  90 . This is accomplished by pin  60  first being anchored in tibia  82 , at which point the tibia drill guide is removed from pin  60  as described above. Flexible drill  70  is then slid over pin  60 , but this time to simply create a straight tunnel, or a tunnel being straight relative to body  24 . Since tibial tunnel  86  is straight, either a straight drill (not shown) standard in the industry or prior art, or flexible drill  70  may be used. Once tibial tunnel  86  is created, flexible drill  70  is removed and the drill guide  20  is inserted in order to locate femur hole  90  at an angle relative to tibia tunnel  86 . The above description for placing femur hole  90  is then followed. 
         [0040]    It should be understood that the foregoing is illustrative and not limiting, and that obvious modifications may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, reference should be made primarily to the accompanying claims, rather than the foregoing specification, to determine the scope of the invention.