Abstract:
A transverse guide assembly for use in passing a transverse pin through a host bone and through a transversely-extending region formed in an interference screw, wherein the transverse guide assembly includes a key member, a boom member and a guide member, and further wherein the key member is adapted to be connected to a keyway formed in the proximal end of the interference screw, the boom member is connected to the key member and supports the guide member outboard of the interference screw, and the guide member is configured to support a drill for forming a hole to receive the transverse pin which extends transversely through the host bone and the transversely-extending region formed in the interference screw.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
   This is a division of U.S. patent application Ser. No. 09/837,594, filed Mar. 18, 2001 now U.S. Pat. No. 6,620,195, by E. Marlowe Goble et al. for APPARATUS AND METHOD FOR ATTACHING A GRAFT LIGAMENT TO A BONE. 

   FIELD OF THE INVENTION 
   The present invention relates to surgical apparatus and methods in general, and more particularly to apparatus and methods for attaching a graft ligament to a bone. 
   BACKGROUND OF THE INVENTION 
   In the human knee, the anterior cruciate ligament (i.e., the ACL) extends between the top end of the tibia and the bottom end of the femur. This ligament plays an important role in providing both static and dynamic stability to the knee. Often, the ACL is ruptured or torn as the result of, for example, a sports-related injury. Consequently, various surgical procedures have been developed for reconstructing the ACL so as to restore normal function to the knee. 
   For example, the ACL may be reconstructed by replacing the damaged ACL with a synthetic or harvested graft ligament. More particularly, with such a procedure, bone tunnels are typically formed in the top end of the tibia and the bottom end of the femur, with one end of the graft ligament being positioned in the femoral tunnel and the other end of the graft ligament being positioned in the tibial tunnel. The two ends of the graft ligament are anchored in place in various ways well known in the art so that the graft ligament thereafter extends between the tibia and the femur in substantially the same way, and with substantially the same function, as the original ACL. 
   In some circumstances, a graft ligament harvested from the body may include a bone block connected to one or both of its ends. For example, a portion of a patella tendon, with a portion of the patella still attached, may be harvested from the patient so as to provide the graft ligament. The graft ligament&#39;s bone block (i.e., the patella block) can facilitate integration of the graft ligament with the patient&#39;s host bone, due to the rapid integration of bone with bone. 
   In other circumstances, a graft ligament harvested from the body may consist entirely of soft tissue. For example, a portion of the hamstring tendon may be harvested from the patient so as to provide the graft ligament. In this case, only the soft tissue is available to integrate with the host bone. 
   In one well-known procedure, the graft ligament is placed in the bone tunnel and then fixed in place using a headless orthopedic screw, generally known as an “interference” (or “Kurosaka”) screw. More particularly, with this procedure, the graft ligament is placed in the bone tunnel and then an interference screw is advanced into the bone tunnel so that the screw extends parallel to the bone tunnel and simultaneously engages both the graft ligament and the host bone. The interference screw essentially drives the graft ligament laterally, into engagement with the opposite side of the bone tunnel, whereby to secure the graft ligament to the host bone. 
   Interference screws work well in many circumstances. Unfortunately, however, interference screws do not work perfectly in all clinical situations. For example, interference screws can have limited effectiveness where bone quality is poor. This can be particularly true in the tibia. In fact, in some circumstances, the bone quality in the tibia can be sufficiently poor that a surgeon will avoid the use of an interference screw altogether and uses some alternative form of ligament fixation. Unfortunately, however, such alternative forms of ligament fixation generally suffer from significant deficiencies of their own. 
   In addition to the foregoing, other objects frequently need to be attached to bone as well. For example, in the area of fracture fixation, bone fragments need to be re-attached to bone. Current attachment techniques typically rely on the use of bone screws and the like to effect re-attachment. However, bone screws typically only provide a single point of purchase with the bone and can provide less than optimal stability, frequently requiring the use of additional screws, etc. 
   SUMMARY OF THE INVENTION 
   Accordingly, a primary object of the present invention is to provide improved apparatus for attaching a graft ligament to a bone. 
   Another object of the present invention is to provide improved apparatus for attaching an object to bone. 
   And another object of the present invention is to provide an improved method for attaching a graft ligament to a bone. 
   Still another object of the present invention is to provide an improved method for attaching an object to bone. 
   These and other objects of the present invention are addressed by the provision and use of a novel fixation system for fixing a graft ligament in a bone tunnel, wherein the fixation system comprises an interference screw comprising a body having a distal end and a proximal end, screw threads extending longitudinally along the body, and a transversely-extending region formed in the body for receiving a transverse pin therein, whereby to securely lock the interference screw, and hence the graft ligament, to the bone. 
   In accordance with a further feature of the present invention, the transversely-extending region formed in the body of the interference screw may comprise a hole formed in the body of the interference screw. 
   And in accordance with a further feature of the present invention, the proximal end of the body of the interference screw has a keyway formed therein so as to permit (i) driving of the interference screw, and (ii) association with a transverse guide assembly for placing a transverse pin through the host bone and through the transversely-extending region formed in the interference screw, whereby to securely lock the interference screw, and hence the graft ligament, to the bone. 
   And in accordance with a further feature of the present invention, there is provided a novel transverse guide assembly for use in passing the transverse pin through the host bone and through the transversely-extending region formed in the interference screw, wherein the transverse guide assembly comprises a key member, a boom member and a guide member, and further wherein the key member is adapted to be connected to the keyway formed in the proximal end of the interference screw, the boom member is connected to the key member and supports the guide member outboard of the interference screw, and the guide member is adapted to support a drill for forming a hole to receive the transverse pin which extends transversely through the host bone and the transversely-extending region formed in the interference screw. 
   In accordance with a further feature of the present invention, there is provided a method for attaching a graft ligament to a bone, the method comprising the steps of: (i) drilling a tunnel in the bone; (ii) positioning the graft ligament in the bone tunnel; (iii) placing an interference screw in the bone tunnel so as to force the graft ligament laterally against the opposite side of the bone tunnel; and (iv) advancing a transverse pin transversely through the bone and through the interference screw so as to lock the interference screw, and hence the graft ligament, to the bone. 
   The present invention can also be applied to attach other objects to bone, e.g., a bone fragment to a bone. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will be more fully disclosed in, 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 side elevational view, partially in section, showing a novel fixation system attaching a graft ligament to a bone; 
       FIG. 2  is a side elevational view of a novel interference screw formed in accordance with the present invention; 
       FIG. 3  is an end view showing the distal end of the interference screw shown in  FIG. 2 ; 
       FIG. 4  is an end view showing the proximal end of the interference screw shown in  FIG. 2 ; 
       FIG. 5  is a side elevational view of a driver which may be used to set the interference screw shown in  FIG. 2 ; 
       FIG. 6  is an end view showing the distal end of the driver shown in  FIG. 5 ; 
       FIG. 7  is side elevational view of a transverse pin which may be used in connection with the present invention; 
       FIG. 8  is an end view showing the proximal end of the transverse pin shown in  FIG. 7 ; 
       FIG. 9  is a side elevational view of a transverse guide assembly formed in accordance with the present invention; 
       FIG. 10  is a sectional view taken along line  10 — 10  of  FIG. 9 ; 
       FIGS. 11–14  are side elevational views, partially in section, showing various steps in attaching a graft ligament to a bone; 
       FIGS. 15–17  are side elevational views, partially in section, showing various steps in an alternative method for attaching a graft ligament to a bone; 
       FIG. 18  is a side elevational view of an alternative form of interference screw formed in accordance with the present invention; 
       FIGS. 19–21  are schematic views showing various ways for effecting fracture fixation using bone screws; and 
       FIG. 22  is a schematic view illustrating a novel form of fracture fixation utilizing the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring first to  FIG. 1 , there is shown a novel fixation system  5  for securing a graft ligament  10  within a bone tunnel  15  of a tibia  20  of a human knee joint. 
   Novel fixation system  5  generally comprises an interference screw  100 , a transverse pin  200  and a transverse guide assembly  300 . 
   Interference screw  100  is shown in greater detail in  FIGS. 2–4 . Interference screw  100  generally comprises a body  105  having a distal end  110  and a proximal end  115 . Screw threads  120  extend longitudinally along body  105 . Preferably screw threads  120  extend along the entire length of the screw, from distal end  110  to proximal end  115 ; however, if desired, screw threads  120  may extend along only a portion of the length of the body. Interference screw  100  is preferably cannulated, with a central lumen  125  extending along its length, whereby the interference screw may be delivered to a surgical site over a guidewire if desired. 
   Interference screw  100  has a transversely-extending region  130  formed in body  105  for receiving transverse pin  200  therein, as will hereinafter be discussed in further detail. Where interference screw  100  is formed out of a relatively permanent material, e.g., metal or plastic, transversely-extending region  130  comprises an opening  135  formed in body  105 , and this opening  135  may or may not be filled with a bioabsorbable material  138  if desired. Where interference screw  100  is formed entirely out of a bioabsorbable material, transversely-extending region  130  may, but need not, comprise such opening  135 . 
   The proximal end  115  of body  105  includes a keyway  140  to permit (i) driving of the interference screw, and (ii) association with transverse guide assembly  300  for placing transverse pin  200  through the host bone (e.g., tibia  20 ) and through transversely-extending region  130  formed in body  105 , whereby to lock the interference screw to the bone. Keyway  140  has a non-circular configuration (e.g., rectangular or ovoid, etc.) and a fixed angular orientation relative to transversely-extending region  130  (e.g., aligned). This construction is important, since it allows the particular angular orientation of transversely-extending region  130  to be determined from the angular orientation of keyway  140 , as will hereinafter be discussed in further detail. 
   Looking next at  FIGS. 5 and 6 , there is shown a driver  145  which may be used to set interference screw  100 . Driver  145  generally comprises a shaft  150  having a distal end  155  and a proximal end  160 . Distal end  155  includes a key projection  165  extending distally from shaft  150 . Key projection  165  is sized so as to be received within keyway  140  of interference screw  100 , whereby interference screw  100  can be turned by shaft  150 . A handle  170  is attached to the proximal end of shaft  150 . Driver  145  is preferably cannulated, with a central lumen  175  extending along its length, whereby driver  145  may be used in conjunction with a guidewire if desired. 
   Shaft  150  of driver  145  preferably has an orientation marking  180  formed thereon. Orientation marking  180  has a fixed angular orientation relative to key projection  165 . This construction is important, since it allows the particular angular orientation of key projection  165  (and, by extension, an interference screw  100  mounted to key projection  165 ) to be determined by the angular orientation of orientation marking  180 , as will hereinafter be discussed in further detail. 
   Looking now at  FIGS. 7 and 8 , transverse pin  200  comprises an elongated shaft  205  having a distal end  210  and a proximal end  215 . Transverse pin  200  may be formed out of a relatively permanent material, e.g., metal or plastic, or a bioabsorbable material, e.g., PLA, PGA, etc. Transverse pin  200  is sized so as to be received within transversely-extending region  130  formed in body  105  of interference screw  100 , as will hereinafter be discussed in further detail. 
   If desired, transverse pin  200  may be smooth, ribbed, threaded, etc., and may be headed or headless. If threaded, the threads may extend along the entire length of the shaft or only a portion thereof (e.g., along only the proximal end of shaft  205 ). 
   Looking next at  FIGS. 9 and 10 , transverse guide assembly  300  includes a key member  305 , a boom member  310 , and a guide member  315 . 
   Key member  305  comprises an elongated body  320  having a distal end  325  and a proximal end  330 . Distal end  325  includes a key projection  335  extending distally from body  320 . Key projection  335  is sized so as to be received within keyway  140  of interference screw  100 , as will hereinafter be discussed in further detail. Elongated body  320  of key member  305  is preferably cannulated, with a central lumen  337  ( FIG. 10 ) extending along its length, whereby transverse guide assembly  300  may be advanced to a surgical site over a guidewire if desired. 
   Boom member  310  has a first portion  340  for connection to key member  305 , and a second portion  345  for connection to guide member  315 . If desired, first portion  340  may be permanently attached to key member  305 , e.g., as shown in  FIG. 9 ; alternatively, it may be selectively detachable from key member  305 . 
   Guide member  315  has a distal end  350  and a proximal end  355 . Guide member  315  is cannulated, with a central lumen  360  extending from distal end  350  to proximal end  355 . Lumen  360  is sized so as to accommodate a drill bit and, thereafter, a transverse pin  200  therein, as will hereinafter be described in further detail. 
   Guide member  315  is attached to second portion  345  of boom member  310 . More particularly, guide member  315  may be permanently attached to second portion  345  if desired or, more preferably, it may be slidably mounted to second portion  345  by passing guide member  315  through a bore  365  formed in second portion  345 . Where guide member  315  is slidingly mounted to second portion  345  by passing guide member  315  through the bore  365  in second portion  345 , guide member  315  may be selectively locked to second portion  345  by a spring-biased pivot lever  370 . More particularly, spring-biased pivot lever  370  includes a center hole  375  which receives guide member  315  therein; when the free end of pivot lever  370  is pressed toward second portion  345 , against the bias of a spring  380 , center hole  375  will be aligned with guide member  315  and guide member  315  will be free to move relative to second portion  345 ; but when the free end of pivot lever  370  is released, so that spring  380  moves the free end of pivot lever away from second portion  345 , center hole  375  will move out of alignment with guide member  315  and guide member  315  will be locked relative to second portion  345 . 
   Regardless of how guide member  315  is attached to boom member  310 , guide member  315  is attached so as to have a fixed angular orientation relative to key projection  335  of key member  305 . This construction is important, since it allows the particular angular orientation of guide member  315  to be determined by the angular orientation of key projection  335  of key member  305 , as will hereinafter be discussed in further detail. 
   Fixation system  5  may be used to attach a graft ligament to a bone. More particularly, and looking now at  FIG. 11 , bone tunnel  15  is formed in bone  20 , and graft ligament  10  is positioned within the bone tunnel. Then interference screw  100  is mounted on driver  145  and advanced (preferably over a guidewire  25 ) into bone tunnel  15  until the interference screw engages both graft ligament  10  and bone  20 . Interference screw  100  essentially drives graft ligament  10  laterally, into engagement with the opposite side  30  of bone tunnel  15 , whereby to press the graft ligament against bone  20 . As driver  145  is turned, its orientation marking  180  can be observed, whereby to determine the angular orientation of interference screw  100 . After interference screw  100  has been properly set, driver  145  is removed. 
   Next, and looking now at  FIG. 12 , transverse guide assembly  300 , with its guide member  315  fit loosely to boom member  310 , has its key member  305  advanced toward interference screw  100 . Key projection  335  is fit into keyway  140  formed in the proximal end of interference screw  100 ; as this occurs, guide member  315  of transverse guide assembly  300  will be automatically aligned with the transversely-extending region  130  formed in body  105  of interference screw  100 . In this respect it will be recalled that where interference screw  100  comprises a substantially permanent material, transversely-extending region  130  comprises an opening  135  in body  105  (which opening  135  may or may not be filled with a bioabsorbable material  138  if desired), and guide member  315  will be aligned with this opening  135 . 
   Then, where guide member  315  is movable relative to boom member  310 , guide member  315  is advanced until its distal end  350  engages an outer surface  35  of bone  20 . This helps secure transverse guide assembly  300  relative to bone  20 . 
   Next, a drill  400  ( FIG. 12 ) is advanced through the central lumen  360  of guide member  315 . Drill  400  is used to drill transversely through bone  20 , bone tunnel  15 , any bioabsorbable material  138  located in the transversely-extending region  130  formed in interference screw  100 , and into the bone on the opposite side  30  of the bone tunnel. Drill  400  may also pass through graft ligament  10 , depending on the angular disposition of guide member  315  and the size of graft ligament  10 . Then drill  400  is withdrawn ( FIG. 13 ), and transverse pin  200  is advanced through the central lumen  360  of guide member  315  ( FIG. 1 ). Transverse pin  200  is passed through bone  20 , across interference screw  100 , and back into bone  20 . Then transverse guide assembly  300  is withdrawn ( FIG. 14 ), leaving interference screw  100 , and hence graft ligament  10 , securely locked to bone  20 . 
   It is also possible to configure transverse guide assembly  300  so that guide member  315  approaches interference screw  100  at an angle other than perpendicular. See, for example,  FIGS. 15–17 , where guide member  315  approaches interference screw  100  at a acute angle. 
   It should also be appreciated that, if desired, a plurality of transversely-extending regions  130  may be provided in interference screw  100 . Where a plurality of transversely-extending regions  130  are provided, the regions may be spaced from one another about the circumference of the interference screw, or about the longitudinal axis of the interference screw, or both. See, for example,  FIG. 18 . 
   In addition to the foregoing, second portion  345  of boom member  310  may permit multiple positions for guide member  315 . This construction is advantageous, for example, in situations where interference screw  100  comprises multiple transversely-extending regions  130 , whereby one or more transverse pins  200  may be passed through the interference screw at various locations. 
   It should be appreciated that fixation system  5  may be used in conjunction with a graft ligament  10  comprising a synthetic or harvested graft ligament. Furthermore, where graft ligament  10  comprises a harvested graft ligament, the graft ligament may consist entirely of soft tissue or it may comprise one or more bone blocks as well. 
   Furthermore, while in the foregoing discussion bone  20  was described as being the tibia, it could also, in the case of an ACL repair, comprise the femur. 
   Additionally, it should be appreciated that the present invention may be used to reconstruct ligaments other than the ACL. Thus, the present invention could be used to reconstruct the posterior cruciate ligament (i.e., the PCL) or a ligament in the elbow, etc. 
   It has also been discovered that is it possible to extend the foregoing concepts to orthopedic screws other than interference screws. More particularly, bone fractures are frequently repaired using bone screws and using bone plates and bone screws. See, for example,  FIG. 19 , which shows a bone screw  100 A securing a bone fragment  20 A to a bone  20 ;  FIG. 20 , which shows a bone plate  500  and a plurality of bone screws  100 A securing a bone fragment  20 A to a bone  20 ; and  FIG. 21 , which shows a bone plate  500  and a plurality of bone screws  100 A securing a plurality of bone fragments  20 A to a bone  20 . 
   Bone screws are available in many configurations. They may have deep threads for cancellous bone (i.e., cancellous screws), or shallow threads for cortical bone (i.e., cortical screws). They may be solid or cannulated; and may comprise fully threaded or lag screws (i.e., screws having threads on the distal end thereof, with a smooth shaft between the threads and the head). 
   In accordance with the present invention, and looking now at  FIG. 22 , there is shown a bone screw  100 A formed in accordance with the present invention. Bone screw  100 A comprises a bone screw of the sort known in the art, except that it incorporates at least one transversely-extending region  130  of the sort previously described, and has a transverse pin  200  passed therethrough in accordance with the present invention. Preferably bone screw  100  also includes a keyway  140  of the sort previously described, so that transverse pin  200  can be placed using a transverse guide assembly  300 . A transverse pin  200  placed through bone screw  100 A provides greater axial and torsional fixation strength for the screw in a bone fragment when compared to a bone screw alone. This greater fixation strength is particularly advantageous in comminuted fractures, where enhanced stabilization of the various fragments will lead to a higher probability of union (i.e., bone healing) and less instability at the fracture site during the healing process. 
   Having thus described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the embodiments shown herein are provided by way of example only, and that various changes and modifications may be effected by one skilled in the art without departing from the scope or spirit of the invention as defined in the claims.