Abstract:
Apparatus is disclosed for reconstructing a ligament, the apparatus including a bone fixation element having a central bore and adapted for positioning in a bone tunnel, a flexible filament configured for holding a graft ligament, and a crimp configured for attachment to the flexible filament so as to prevent movement of the graft ligament in the bone tunnel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims benefit of prior U.S. Provisional Patent Application Ser. No. 60/237,817, filed Oct. 3, 2000 by E. Marlowe Goble for METHOD AND APPARATUS FOR RECONSTRUCTING A LIGAMENT, now abandoned , which patent application is hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     This invention relates to medical procedures and apparatus in general, and more particularly to bone fixation systems and related medical procedures that can be used in reconstructing a ligament. 
     2. The Relevant Technology 
     A ligament is a piece of fibrous tissue which connects one bone to another. Ligaments are frequently damaged (e.g., detached or torn or ruptured, etc.) as the result of injury and/or accident. A damaged ligament can impede proper motion of a joint and cause significant pain. 
     Various procedures have been developed to repair or replace a damaged ligament. The specific procedures used depend on the particular ligament which is to be restored and on the extent of the damage. 
     One ligament which is frequently damaged as the result of injury and/or accident is the anterior cruciate ligament (ACL). Looking now at  FIG. 1 , the ACL  5  extends between the top of the tibia  10  and the bottom of the femur  15 . A damaged ACL can cause instability of the knee joint and cause substantial pain and arthritis. 
     Numerous procedures have been developed to restore the ACL through a graft ligament replacement. In general, and looking now at  FIG. 2 , these ACL replacement procedures involve drilling a bone tunnel  20  through tibia  10  and up into femur  15 . Then a graft ligament  25 , consisting of a harvested or artificial ligament or tendon(s), is passed through the tibial portion  30  of tunnel  20  (sometimes referred to as the “tibial tunnel”), across the interior of the joint, and up into the femoral portion  35  of tunnel  20  (sometimes referred to as the “femoral tunnel”). Then a distal portion of graft ligament  25  is secured in femoral tunnel  35 , and a proximal portion of graft ligament  25  is secured in tibial tunnel  30 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which are to be considered together with the accompanying drawings wherein like numbers refer to like pars and further wherein: 
         FIG. 1  is an elevated side view of a knee joint having an anterior cruciate ligament; 
         FIG. 2  is a side view of the knee joint shown in  FIG. 1  with the anterior cruciate ligament replaced by a graft ligament; 
         FIG. 3  is a cross sectional side view of a knee joint having a drill guide partially disposed within a bone tunnel formed on the tibia and femur; 
         FIG. 4  is a perspective view of an alternative embodiment of the drill guide shown in  FIG. 3 ; 
         FIG. 5  is a top perspective view of a portion of the drill guide shown in  FIG. 4 ; 
         FIG. 6  is a bottom perspective view of a portion of the drill guide shown in  FIG. 4 ; 
         FIG. 7  is a cross sectional side view of the knee joint shown in  FIG. 3  having the drill and barrel guide removed; 
         FIG. 8  is a cross sectional side view of the knee joint shown in  FIG. 7  with a suture engaged with the endosteal guide; 
         FIG. 9  is a cross sectional side view of the knee joint shown in  FIG. 8  with a cannulated screw passed over the suture and driven into the angled tunnel; 
         FIG. 10  is a cross sectional side view of the knee joint shown in  FIG. 9  with the endosteal guide removed from the bone tunnel; 
         FIG. 11  is a cross sectional side view of the knee joint shown in  FIG. 10  with a graft ligament attached to the suture; 
         FIG. 12  is a cross sectional side view of the knee joint shown in  FIG. 11  with the draft ligament drawn into the bone tunnel and a crimp secured to the suture; 
         FIG. 13  is a cross sectional side view of the knee joint shown in  FIG. 12  wherein the graft ligament is depicted as a bone-tendon-bone graft that is coupled with the suture and is disposed outside of the bone tunnel; 
         FIG. 14  is a cross sectional side view of the knee joint shown in  FIG. 13  wherein the bone-tendon-bone graft is drawn into the bone tunnel; 
         FIG. 15  is a cross sectional side view of the knee joint shown in  FIG. 7  wherein a grasper disposed within the bone tunnel is grasping a suture passed through the angled tunnel; 
         FIG. 16  is a cross sectional side view of the knee joint shown in  FIG. 7  wherein the suture has been pulled through the bone tunnel by the grasper; 
         FIG. 17  is an elevated side view of an assembly including a suture, cannulated screw, collet, and drivers; 
         FIG. 18  is a back perspective view of the cannulated screw and collet shown in  FIG. 17 ; 
         FIG. 19  is a cross sectional side view of the cannulated screw shown in  FIG. 18 ; 
         FIG. 20  is a cross sectional side view of the assembled suture, cannulated screw, collet shown in  FIG. 17 ; and 
         FIG. 21  is a perspective view of the driver for driving the cannulated screw and the driver for driving the collet as shown in  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     There are numerous ways in which graft ligament  25  may be loaded into bone tunnel  20  and then secured in position. The present invention is directed to a new method for positioning a graft ligament  25  in bone tunnel  20  and for securing the graft ligament in position, and to new apparatus for use in the same. 
     More particularly, and looking now at  FIG. 3 , after bone tunnel  20  (consisting of tibial tunnel  30  and femoral tunnel  35 ) has been drilled, a drill guide  40  is inserted into the bone tunnel  20 . Specifically, the drill guide  40  has an endosteal guide  45  passed up tibial tunnel  30 , across the interior of the knee joint, and then up femoral tunnel  35 . Then an anterolateral portal is made on the anterior border of the IT band, and an angled tunnel  50  is drilled from the periosteum to the proximal end of femoral tunnel  35 . Thus, angled tunnel  50  opens on, and communicates with, femoral tunnel  35 . In this respect it should be appreciated that drill guide  40  is essentially a cross-pin drill guide of the sort well known in the art, except modified so as to enable the angled tunnel  50  to be drilled at an acute angle (e.g., 45 degrees) to the axis of femoral tunnel  35 . 
     If desired, drill guide  40  can be set so as to always drill the angled tunnel  50  at the same angle (e.g., 30 or 45 or 60 degrees, etc.), or the approach may be straight, i.e., aligned with the femoral tunnel (e.g., at 0 degrees), or drill guide  40  can be configured so as to be adjustable, whereby the surgeon can select the specific angle of angled tunnel  50 . By way of example but not limitation, some details regarding the construction of one preferred form of drill guide  40  is shown in  FIGS. 4–6 . 
     Looking next at  FIG. 7 , after angled tunnel  50  is drilled, the drill and barrel guide are removed from drill guide  40 . The drill guide  40  is then rotated about the axis of bone tunnel  20  so as to swing the head of drill guide  40  away from the entrance to angled tunnel  50 , whereby to provide convenient access to the entrance of angled tunnel  50 . 
     Looking next at  FIG. 8 , a braided wire suture  55  is inserted down angled tunnel  50  and “grabbed” by the distal end of endosteal guide  45 . To this end, the endosteal guide  45  may include some sort of grippers at its distal end, or the end of the wire suture  55  may include a loop at its distal end and the endosteal guide  45  may include some sort of hook at its distal end, or the end of the endosteal guide  45  may include some sort of loop at its distal end and the end of the wire suture  55  may include some sort of hook at its distal end, etc. Alternatively, endosteal guide  45  may be cannulated so as to permit grippers or a hook to be passed down the interior of the endosteal guide  45  to grab the distal end of the wire suture  55 . In any case, the endosteal guide  45  and wire suture  55  are configured so as to permit the distal end of the endosteal guide  45  to connect up with the distal end of the wire suture  55 . 
     Referring next to  FIG. 9 , once the distal end of endosteal guide  45  is connected with the distal end of wire suture  55 , a cannulated screw  60  is slid down the wire suture  55  and screwed into angled tunnel  50 . This can be done by using a cannulated driver (not shown in  FIG. 9 ) of the sort well known in the art. Cannulated screw  60  is screwed into femur  10  until the head of the screw  60  contacts the periosteum so that the head of the screw  60  does not stand proud above the bone. Cannulated screw  60  essentially acts as a sort of liner for angled tunnel  50 , providing a bearing surface for wire suture  55  so as to prevent the wire suture  55  from cutting into femur  15  as the wire suture  55  is moved through angled tunnel  50 , as will hereinafter be discussed. 
     Next, and looking now at  FIG. 10 , drill guide  40  is withdrawn from the surgical site. As this occurs, the endosteal guide  45  of drill guide  40  is removed from bone tunnel  20 , causing wire suture  55  to be pulled down femoral tunnel  35 , across the interior of the knee joint, down tibial tunnel  30  and then out the bottom end of the tibial tunnel  30 . 
     Then, as shown in  FIG. 11 , the graft ligament  25 , e.g., one or more strands of a hamstring tendon, is attached to the distal end of wire suture  55 . In the case where the graft ligament  25  comprises one or more strands of hamstring tendon, such attachment can be easily accomplished by forming a loop at the lower end of wire suture  55  and then passing the tendon strand(s) through the loop, in the manner shown in  FIG. 11 . 
     Next, as shown in  FIG. 12 , wire suture  55  is pulled proximally so as to tow graft ligament  25  up bone tunnel  20  until the distal end of the graft ligament  25  is positioned in femoral tunnel  35  and the proximal end of the graft ligament  25  is positioned in tibial tunnel  30 . Then a crimp  65  is attached to wire suture  55  adjacent to cannulated screw  60  so that engagement of crimp  65  with cannulated screw  60  will prevent the wire suture  55  from being pulled back in the tibial direction. Next, graft ligament  25  is tensioned by pulling the proximal end of the graft ligament  25  in the proximal direction. The proximal end of the graft ligament  25  is then fixed to the tibia in ways well known in the art. 
     If desired, the proximal end of cannulated screw  60  can have a modest recess therein so as to receive crimp  65  when the ligament is tensioned, whereby to keep the crimp from standing proud above the femur. Alternatively, the bone screw  60  can be eliminated, utilizing only the crimp  65  on the wire suture  55  to prevent distal migration. Finally, the end of wire suture  55  proximal to crimp  65  is trimmed off, thus effectively completing the ACL reconstruction procedure. 
     In the foregoing description, and in  FIGS. 11 and 12 , graft ligament  25  was discussed in the context of comprising one or more strands of hamstring tendon. However, it should also be appreciated that graft ligament  25  may comprise other constructs as well. Thus, for example, graft ligament  25  may comprise one or more bone blocks attached to a tendon (e.g., a so-called “bone-tendon-bone” graft), or a totally artificial prosthesis, etc. 
     By way of example but not limitation,  FIGS. 13 and 14  show a bone-tendon-bone graft being towed into position within bone tunnel  20 . In this case, wire suture  55  may be attached to the leading bone block  70 , e.g., by passing the wire suture  55  through one or more holes formed in the bone block  70  and making it fast. If desired, a second wire suture  75  may be attached to the trailing bone block  80  so as to fasten the trailing end of the ligament graft to tibia  10  in ways well known in the art. 
     It should be appreciated that the aforementioned procedure and apparatus may be modified without departing from the scope of the present invention. Thus, for example, and looking now at  FIG. 15 , in one alternative reconstruction procedure, after angled tunnel  50  has been drilled, drill guide  40  is completely removed from the surgical site. Then a wire suture  55 , preferably having a loop  83  at its distal end, is passed down angled tunnel  50  until the wire suture  55  begins to pass into the top end of femoral tunnel  35 . 
     Next, a suture grasper  85  passed up bone tunnel  20  until the distal end of the suture grasper  85  is positioned adjacent to the distal end of wire suture  55 . The suture grasper  85  is then used to pick up the distal end of wire suture  55  and draw the wire suture  55  down femoral tunnel  35 , across the interior of the knee joint, down tibial tunnel  30 , and finally out the front of tibia  10 , as shown in  FIG. 16 . The cannulated screw  60  can then be mounted on the proximal end of wire suture  55 , the cannulated screw  60  screwed down into the periosteum, the distal end of wire suture  55  fastened to the graft ligament  25 , the wire suture  55  retracted so as to tow the graft ligament  25  up bone tunnel  20  and into position, the crimp  65  applied to the wire suture  55 , and then the graft ligament  25  made fast to the tibia, all in substantially the same manner as previously described. 
     In another alternative reconstruction procedure, cannulated screw  60  and crimp  65  may be replaced by an alternative construction. More particularly, and looking now at FIGS.  17 – 19 , a cannulated screw  90  and an associated threaded collet  95  are shown. Cannulated screw  90  has the usual external threads  100  and central bore  105 . Cannulated screw  90 , however, also has a threaded counterbore  110  terminating, intermediate the cannulated screw  90 , in a smooth tapered section  115 . Correspondingly, threaded collet  95  comprises a leading tapered section  120 , a trailing threaded section  125 , and a central bore  130 . The leading tapered section  120  of collet  95  is slit, whereby the tapered section  120  can be forced radially inward so as to close down the diameter of the central bore  130  of collet  95 . Depicted in  FIG. 20 , cannulated screw  90  and threaded collet  95  are sized so that the threaded collet  95  may be lightly screwed into the rear of cannulated screw  90  and wire suture  55  threaded therethrough. Thereafter, threaded collet  95  may be screwed further into cannulated screw  90  so that the nose of the threaded collet  95  will close down on wire suture  55 , thereby clamping the wire suture  55  to the threaded collet  95  and, hence, to the cannulated screw  90 . 
       FIGS. 17 and 21  show drivers for advancing and, alternatively, retracting cannulated screw  90  and threaded collet  95 . More particularly, a first cannulated driver  135  is provided for turning cannulated screw  90 . A second cannulated driver  140  is provided for turning threaded collet  95 . Second cannulated driver  140  may be positioned within first cannulated driver  135 , as will hereinafter be discussed. 
     In use, after wire suture  55  had been passed through angled tunnel  50 , cannulated screw  90 , threaded collet  95 , second driver  140  and first driver  135  are mounted on the proximal end of wire suture  55  ( FIG. 17 ). Next, the components are manipulated so that threaded collet  95  is lightly threaded into cannulated screw  90 , second driver  140  is engaged with threaded collet  95 , and first driver  135  is engaged with cannulated screw  90 . Then the aforementioned assembly is moved down wire suture  55  until the leading tip of cannulated screw  90  engages the femur, whereupon first driver  135  is used to drive the cannulated screw into the femur. 
     At this point, cannulated screw  90  lines angled tunnel  50 , but wire suture  55  is free to move relative to cannulated screw  90  and, hence, the patient&#39;s anatomy. Wire suture  55  is then used in the manner previously described to pick up graft ligament  25  and tow the graft ligament  25  back up into position within the bone tunnel. Once the graft ligament  25  is in position, wire suture  55  is made fast by screwing threaded collet  95  further into cannulated screw  90 , using second driver  140 , until the leading tip of the threaded collet  95  closes down on wire suture  55 , whereupon the wire suture  55  is clamped to the threaded collet  95  and, hence, the cannulated screw  90 . Once this has been achieved, drivers  135  and  140  may be removed, the excess wire  55  trimmed away, and the tibial side of the graft secured. 
     It should also be appreciated that the procedure and apparatus described above may be used for purposes other than an ACL repair, e.g., they may be used to repair other ligaments, the apparatus may be used in other types of surgical procedures such as trauma, spine, etc. 
     Also, the wire suture may be braided polyethylene or monofilament suture; and the cannulated screw and/or threaded collet may be plastic or even reabsorbable.