Abstract:
A crosspin for supporting a graft ligament in a first bone tunnel formed in a bone. The crosspin is positioned in a second bone tunnel extending transverse to, and intersecting, the first bone tunnel. The crosspin is adapted to be drawn through the second bone tunnel by a flexible member attached to a distal portion of the cross pin. The crosspin includes a connector for releasably connecting the distal portion of the crosspin to an intermediate portion, such that the distal portion is separable from said intermediate portion.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
   This is a continuation of prior U.S. patent application Ser. No. 09/619,105, filed Jul. 19, 2000, now U.S. Pat. No. 6,752,830 by E. Marlowe Goble et al. for APPARATUS AND METHOD FOR RECONSTRUCTING A LIGAMENT, which in turn claims benefit of prior U.S. Provisional Patent Application Ser. No. 60/144,773, filed Jul. 20, 1999 by Eugene Marlowe Goble et al. for DEVICE AND METHOD TO HOLD GRAFT WITH A TRANSVERSE PIN. 

   FIELD OF THE INVENTION 
   This invention relates to medical devices and procedures in general, and more particularly to medical devices and procedures for reconstructing a ligament. 
   BACKGROUND OF THE INVENTION 
   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 . 
   OBJECTS OF THE INVENTION 
   One object of the present invention is to provide improved apparatus for positioning the graft ligament in the bone tunnel and/or for securing the graft ligament within the bone tunnel. 
   Another object of the present invention is to provide an improved method for reconstructing a ligament. 
   SUMMARY OF THE INVENTION 
   These and other objects of the present invention are addressed by novel apparatus and method for reconstructing a ligament. 
   In one preferred form of the invention, the invention comprises a crosspin for supporting a graft ligament in a first bone tunnel formed in a bone, by positioning the crosspin in a second bone tunnel extending transverse to, and intersecting, the first bone tunnel, the crosspin comprising: a shaft having a distal portion, in intermediate portion, and a proximal portion; the distal portion comprising attachment means for attaching a flexible member to the shaft; the intermediate portion comprising screw threads; and the proximal portion including driver engagement means for engagement by a driver adapted to turn the shaft; whereby the crosspin may be drawn through the second transverse bone tunnel by a flexible member attached to the distal portion by the attachment means, and the crosspin may have its screw threads turned into the bone by a driver engaged with the engagement means. 
   In another form of the invention, the invention comprises a crosspin for supporting a graft ligament in a first bone tunnel formed in a bone, by positioning the crosspin in a second bone tunnel extending transverse to, and intersecting, the first bone tunnel, the crosspin comprising: a shaft having a distal portion, in intermediate portion, and a proximal portion; the distal portion having a flexible member attached thereto; the intermediate portion comprising screw threads; and the proximal portion including driver engagement means for engagement by a driver adapted to turn the shaft; whereby the crosspin may be drawn through the second transverse bone tunnel by the flexible member, and the crosspin may have its screw threads turned into the bone by a driver engaged with the engagement means. 
   In another form of the invention, the invention comprises a crosspin for supporting a graft ligament in a first bone tunnel formed in a bone, by positioning the crosspin in a second bone tunnel extending transverse to, and intersecting, the first bone tunnel, the crosspin comprising: a cannulated shaft having a distal portion, in intermediate portion, and a proximal portion; the intermediate portion comprising screw threads; and the proximal portion including driver engagement means for engagement by a driver adapted to turn the shaft; whereby the crosspin may be positioned in the second transverse bone tunnel by loading the crosspin on, and moving the crosspin along, the flexible member, and the crosspin may have its screw threads turned into the bone by a driver engaged with the engagement means. 
   In another form of the invention, the invention comprises a method for securing a graft ligament in a bone tunnel, wherein the graft ligament comprises a bone block and a ligament attached to the bone block, the method comprising the steps of: (1) forming a first bone tunnel in a bone, and forming a second bone tunnel in the same bone, the second bone tunnel being transverse to, and intersecting, the first bone tunnel; and (2) positioning the graft ligament in the first bone tunnel, and positioning a crosspin in the second transverse bone tunnel, so that the bone block is positioned in the first bone tunnel on one side of the crosspin and the ligament is positioned in the first bone tunnel so that the ligament extends past the crosspin to the other side of the crosspin, whereby when tension is applied to the end of the ligament opposite from the bone block, the bone block will be stopped from movement past the crosspin by engagement of the bone block with the crosspin. 
   In another form of the invention, the invention comprises a method for securing a graft ligament in a bone tunnel, wherein the graft ligament comprises a bone block and a ligament attached to the bone block, the method comprising the steps of: (1) forming a first bone tunnel in a bone, and forming a second bone tunnel in the same bone, the second bone tunnel being transverse to, and intersecting, the first bone tunnel; and (2) positioning the graft ligament in the first bone tunnel, and positioning a crosspin in the second transverse bone tunnel, so that the bone block is positioned in the first bone tunnel on one side of the crosspin, and the ligament is positioned in the first bone tunnel so that the ligament extends past the crosspin to the other side of the crosspin, loops over the crosspin, and extends past the crosspin back to the first side of the crosspin, whereby when tension is applied to the end of the ligament opposite from the bone block, the bone block will be stopped from movement past the crosspin by engagement of the bone block with the crosspin. 
   In another form of the invention, the invention comprises apparatus for securing a graft ligament in a bone tunnel, wherein the graft ligament comprises a bone block and a ligament attached to the bone block, the apparatus comprising: a plate having a body with an opening formed therein, and a plurality of pointed legs extending therefrom, the body being sized to receive the bone block between the pointed legs; and a crosspin comprising a shaft and screw threads formed thereon, the shaft being sized to pass through the opening such that the crosspin may secure the bone block to the wall of the bone tunnel. 
   In another form of the invention, the invention comprises a method for securing a graft ligament in a bone tunnel, wherein the graft ligament comprises a bone block and a ligament attached to the bone block, the method comprising the steps of: (1) forming a first bone tunnel in a bone, and forming a second bone tunnel in the same bone, the second bone tunnel being transverse to, and intersecting, the first bone tunnel, and providing a plate having a body with an opening formed therein, and a plurality of pointed legs extending therefrom, the body being sized to receive the bone block between the pointed legs, and providing a crosspin comprising a shaft and screw threads formed thereon; (2) positioning the graft ligament and the plate in the first bone tunnel, and positioning the crosspin in the second transverse bone tunnel, so that the crosspin extends through the opening in the plate and urges the plate against the bone block, whereby the graft ligament will be secured in the first bone tunnel. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above 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 is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
       FIG. 1  is a schematic side view of a knee joint, showing an ACL extending between the top of the tibia and the bottom of the femur; 
       FIG. 2  is a schematic side view of the same knee joint, except showing portions of an ACL reconstruction; 
       FIGS. 3–7  are schematic front views of a knee joint, illustrating a crosspinning procedure utilizing a first type of crosspin; 
       FIG. 8  is a schematic front view of a knee joint, illustrating a crosspinning procedure utilizing a second type of crosspin; 
       FIG. 9  is a schematic front view of a knee joint, illustrating a crosspinning procedure utilizing a third type of crosspin; 
       FIGS. 10–12  are schematic views illustrating a crosspinning procedure utilizing a graft ligament comprising a bone block; 
       FIGS. 13–15  are schematic views illustrating another crosspinning procedure utilizing a graft ligament comprising a bone block; 
       FIGS. 16–18  are schematic views illustrating still another crosspinning procedure utilizing a graft ligament comprising a bone block; 
       FIGS. 19–21  are schematic views illustrating a crosspinning procedure utilizing a plate and a graft ligament comprising a bone block; and 
       FIG. 22  is a schematic view illustrating another crosspinning procedure utilizing a plate and a graft ligament comprising a bone block. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Non-Cannulated Crosspin 
   In one form of the invention, there is provided a novel non-cannulated crosspin for supporting a graft ligament in a bone tunnel. 
   More particularly, and looking now at  FIG. 3 , during one type of ACL reconstruction, the bone tunnel  20  is formed by drilling through tibia  10  and up into femur  15 , whereby to form tibial tunnel  30  and femoral tunnel  35 . Then a transverse bone tunnel  40  is formed in femur  15  so that transverse bone tunnel  40  intersects femoral tunnel  35 . Bone tunnel  20  bifurcates transverse bone tunnel  40  into two tunnel portions, a first transverse bone tunnel portion  45  and a second transverse bone tunnel portion  50 . 
   After transverse bone tunnel  40  has been formed, a flexible member  55  is used to draw graft ligament  25  up into place. 
   There are a number of ways that this may be accomplished and, for the purposes of the present invention, all are satisfactory. However, for purposes of example but not limitation, a particular method for drawing graft ligament  25  into place using flexible member  55  will now be reviewed. 
   First, flexible member  55  is threaded through transverse bone tunnel  40 . Then a crochet-hook device (not shown) is passed up tibial tunnel  30 , across the interior of the knee joint, and up femoral tunnel  35 . The crochet-hook device is used to hook flexible member  55  at the intersection of bone tunnel  20  and transverse bone tunnel  40 . Then the crochet-hook device is used to pull flexible member  55  down femoral tunnel  35 , across the interior of the knee joint, down tibial tunnel  30 , and out the front side of tibia  10 . Next, graft ligament  25  is looped over flexible member  55  ( FIG. 3 ). If desired, graft ligament  25  can be secured around flexible member  55  by a suture, a clip or a tie device (not shown) so as to prevent graft ligament  25  from slipping off flexible member  55 . Flexible member  55  is then used to pull the looped graft ligament  25  up tibial tunnel  30 , across the interior of the knee joint, and then up into femoral tunnel  35  ( FIG. 4 ). 
   Once graft ligament  25  and flexible member  55  have assumed the position shown in  FIG. 4 , the graft ligament may be retained in that position through the use of a novel non-cannulated crosspin. 
   More particularly, and looking now at  FIGS. 5–7 , graft ligament  25  may be supported in femoral tunnel  35  with a novel crosspin  60 . Crosspin  60  generally comprises a solid shaft  65  having a distal portion  66 , an intermediate portion  67  and a proximal portion  68 . One or more openings  70  are formed in the shaft&#39;s distal portion  66 , and screw threads  75  are formed in the shaft&#39;s intermediate portion  67 , adjacent to proximal portion  68 . Crosspin  60  also comprises a recess  80  in its proximal portion  68  for receiving the front end of a driver  85  ( FIG. 6 ). 
   Crosspin  60  is deployed by (1) attaching one end,  55 A, of flexible member  55  to crosspin  60  using openings  70  ( FIG. 5 ); (2) drawing crosspin  60  across first transverse bone tunnel portion  45 , under the looped graft ligament  25 , across second transverse bone tunnel portion  50 , and out the far side of transverse bone tunnel  40 , until the crosspin&#39;s screw threads  75  engage femur  15 ; (3) turning crosspin  60  with driver  85  so that threads  75  are set into femur  15  ( FIG. 6 ); and (4) removing the distal and proximal portions of crosspin  60  that extend beyond the outside surfaces of femur  15  ( FIG. 7 ). 
   Non-Cannulated Crosspin with Pre-Attached Flexible Member 
   Looking next at  FIG. 8 , there is shown a novel non-cannulated crosspin  60 A which is similar to the crosspin  60  described above, except that the distal portion  66 A of crosspin  60 A has flexible member  55  permanently attached thereto. Thus, with crosspin  60 A, flexible member  55  does not need to be connected to the crosspin at the time of use, as is the case with the crosspin  60  discussed above. With this one exception, crosspin  60 A is intended to be used in substantially the same way as the crosspin  60  discussed above. 
   As an additional alternative construction, distal portion  66 A of crosspin  60 A may be joined to intermediate portion  67 A of the crosspin through a male/female screw mount, such as is shown generally at  90 . Such a feature facilitates removal of distal portion  66 A from intermediate portion  67 A after the crosspin has been set in femur  15 . Of course, if desired, such a screw mount may also be incorporated into the construction of the crosspin  60  discussed above. 
   Cannulated Crosspin 
   Looking next at  FIG. 9 , there is shown a novel cannulated crosspin  60 B. Crosspin  60 B is identical to the crosspin  60  discussed above, except that (1) crosspin  60 B lacks the openings  70  formed in the distal portion  66  of the crosspin  60  discussed above, and (2) crosspin  60 B is cannulated along its length with a longitudinal bore  95 . 
   In use, flexible member  55  and graft ligament  25  are first positioned in the manner shown in  FIG. 4 , and then crosspin  60 B is slipped over the free end  55 A of flexible member  55 , with flexible member  55  being received in the crosspin&#39;s longitudinal bore  95 . Crosspin  60 B is then advanced along flexible member  55  so that the crosspin passes through first transverse bone tunnel portion  45 , under the looped graft ligament  25 , and through second transverse bone tunnel portion  50 , until the crosspin&#39;s threads  75 B engage the outer surface of femur  15 . A cannulated driver (not shown, but similar to the driver  85  shown in  FIGS. 6–8 , except that it is cannulated) is then loaded over the free end  55 A of flexible member  55 , advanced along flexible member  55 , and then used to advance crosspin  60 B so that the crosspin&#39;s screw threads  75 B are set in femur  15 . The cannulated driver is then withdrawn, flexible member  55  is removed, and the crosspin&#39;s protruding distal portion  66 B and proximal portion  60 B trimmed off so as to complete the crosspinning procedure. 
   Crosspinning a Graft Ligament Comprising a Bone Block 
   In another novel aspect of the present invention, and looking now at  FIGS. 10–18 , there is disclosed a novel method for crosspinning a graft ligament comprising a bone block. 
   More particularly, in the preceding sections, the present invention has been discussed in the context of a graft ligament  25  comprising a loop of soft tissue, e.g., a hamstring tendon. However, it is also possible to crosspin a graft ligament comprising a bone block. 
   More particularly, and looking now at  FIGS. 10 and 11 , there is shown a graft ligament  25 A comprising a ligament  100  and a bone block  105 . By way of example but not limitation, graft ligament  25 A might be a patellar graft comprising a portion of the patella tendon and a portion of the patella. Such graft ligaments are sometimes preferred since ligament  100  is naturally, and hence securely, attached to bone block  105 , and since it is relatively easy to achieve good osseointegration between bone block  105  and femur  15 . 
   In accordance with a teaching of the present invention, graft ligament  25 A is positioned in bone tunnel  20  so that bone block  105  resides distal to crosspin  60 A, i.e., so that bone block  105  resides outboard of crosspin  60 A relative to the interior of the joint. As a result, when graft ligament  25 A is thereafter placed under tension, crosspin  60 A will prevent the bone block  105  from passing by the crosspin, whereby graft ligament  25 A will be maintained in position. 
     FIG. 12  illustrates how graft ligament  25 A may be loaded onto flexible member  55  so that it achieves the position shown in  FIGS. 10 and 11 . If desired, a suture  110  ( FIGS. 11 and 12 ) may be used to help keep graft ligament  25 A properly positioned relative to flexible member  55  and, subsequently, crosspin  60 A. 
   Similarly, and looking now at  FIGS. 13 and 14 , the graft ligament  25 A may also be secured in position by positioning bone block  105  proximal to crosspin  60 A, with ligament lob looping over crosspin  60 A before passing proximally out of femoral tunnel  35 . As a result, when graft ligament  25 A is thereafter placed under tension, crosspin  60 A will prevent the bone block  105  from passing by the crosspin, whereby graft ligament  25 A will be maintained in position. 
     FIG. 15  illustrates how graft ligament  25 A may be loaded onto flexible member  55  so that it subsequently achieves the position shown in  FIGS. 13 and 14  with respect to crosspin  60 A. 
   Furthermore, and looking now at  FIGS. 16 and 17 , if desired, a suture  110  may be used to hold the graft ligament in a looped form. Again,  FIG. 18  illustrates how graft ligament  25 A may be loaded onto flexible member  55  so that it subsequently achieves the position shown in  FIGS. 16 and 17  with respect to crosspin  60 A. 
   With respect to the bone-block-based crosspinning techniques described above and illustrated in  FIGS. 10–18 , it should also be appreciated that while the techniques have been discussed in the context of the aforementioned crosspin  60 A, they may also be practiced equally well with the crosspins  60  and  60 B discussed above, as well as with other crosspins well known in the art. 
   Crosspinning Procedure Utilizing a Plate and a Graft Ligament Comprising a Bone Block 
   In yet another preferred embodiment of the present invention, and looking now at  FIGS. 19–21 , there is shown a plate  115  which may be used to secure bone block  105  of graft ligament  25 A to femur  15 . Plate  115  comprises a body portion  120 , an opening  125  formed in body portion  120 , and a plurality of pointed legs  130 . 
   Plate  115  is arranged to have flexible member  55  passed through opening  125 , and bone block  105  seated against body portion  120  ( FIG. 19 ), with or without a securing suture  131 , whereby flexible member  55  may be used to draw plate  115 , and hence graft ligament  25 A, up into position in femur  15  ( FIG. 20 ) Thereafter, a cannulated crosspin  135 , comprising a shaft  140  and enlarged screw threads  145 , is passed over flexible member  55  and into first transverse bone tunnel portion  45 . Crosspin  135  is then advanced within transverse bone tunnel  40  so that the crosspin&#39;s shaft  140  passes through opening  125  in plate  115  and into second transverse bone tunnel portion  50 , and so that the crosspin&#39;s enlarged screw threads  145  engage the outside surface of femur  15 . A cannulated driver (not shown) is then used to advance crosspin  135  further into transverse bone tunnel  40 . By sizing the plate&#39;s opening  125  so that it will make a snug fit with the crosspin&#39;s shaft  140 , the crosspin will drive plate  115  laterally, whereby to drive the plate&#39;s pointed legs  130  into the side wall of femoral tunnel  35 , and whereby to hold bone block  105  securely against the side wall of the bone tunnel ( FIG. 21 ). Flexible member  55  may thereafter be removed so as to complete the crosspinning procedure. 
   Looking next at  FIG. 22 , it is also possible to use crosspin  60 A in conjunction with plate  115 . In this case it is desirable to size the plate&#39;s opening  125  so that it will make a snug fit with the shaft of crosspin  60 A, whereby the crosspin will drive the plate laterally against the side wall of femoral tunnel  35 , whereby to fix graft ligament  25 A in position. 
   With respect to the plate-and-bone-block-based crosspinning techniques described above and illustrated in  FIGS. 19–22 , it should also be appreciated that while the techniques have been discussed in the context of the aforementioned crosspins  135  and  60 A, they may also be practiced equally well with the crosspins  60  and  60 B discussed above, as well as with other crosspins well known in the art. 
   The inventions discussed in the preceding sections can be comprised of any material applicable to orthopedic fixation devices such as implantable metallic, polymeric, composite, biologic or ceramic materials. However, in the case of the non-cannulated crosspins  60  and  60 A, the solid cross-section unique to non-cannulated devices provides shear strength greater than that of similar diameter cannulated devices. Connection features, such as the openings  70  and threads  90 , allow the non-cannulated crosspins  60  and  60 A to be pulled through the knee and placed without any of the cross-sectional area being used for guidance tools such as the flexible member  55 . This additional cross-sectional area helps to strengthen the portion of the crosspin that is under load by the ACL graft in actual clinical use. This consequently allows the non-cannulated crosspin with solid cross-sectional area to be made from a material which is typically weaker in shear strength than metal, such as non-absorbable or absorbable polymeric, composite, biologic or ceramic biomaterials, without significantly compromising the crosspin holding strength.