Bicortical tibial fixation of ACL grafts

Abstract

A method of securing a graft in a bone tunnel, in which graft is secured within the tunnel at both the entrance and the exit ends of the tunnel to provide bicortical fixation of the graft in the bone. Interference screws or other fixation devices are used to secure the graft within the tunnel. For tibial tunnel fixation using an interference screw, the back end of the distal screw is angled so that it closely approximates the angle of the outer tibial tunnel rim. The distal screw is non-cannulated to prevent hematomas from being formed by blood flowing from the tibial tunnel into the surrounding soft tissue. The proximal screw has a restricted cannula to minimize the flow of synovial fluid entering the tibial tunnel. Advantageously, the space between the two screws fills with blood to promote faster healing and incorporation of the graft in the tibial tunnel.

1. A method of securing a graft in a single bone, the method comprising the steps of:
 (a) forming a tunnel through the single bone, the tunnel having an entrance and an exit at opposing ends of the tunnel; 
 (b) subsequently to step (a), extending a portion of the graft within the tunnel between the entrance and the exit; and 
 (c) subsequently to step (b), securing the graft within the tunnel to cortical bone by inserting and rotating interference screws at both the entrance and the exit of the tunnel to provide bicortical fixation of the portion of the graft in the tunnel. 
 
     
     
       2. The method of  claim 1 , wherein the step of securing the graft comprises installing an interference fixation device at each of the opposing ends of the tunnel. 
     
     
       3. The method of  claim 1 , further comprising the steps of extending the graft between the bone and another bone, and securing the graft to the other bone. 
     
     
       4. The method of  claim 1 , wherein the step of securing the graft is performed using interference screws. 
     
     
       5. The method of  claim 1 , wherein the step of securing the graft is performed using an adhesive. 
     
     
       6. The method of  claim 1 , wherein the bone is a tibia. 
     
     
       7. The method of  claim 1 , wherein the graft replaces an anterior cruciate ligament. 
     
     
       8. A set of fixation devices for securing a graft an autograft or allograft in a tunnel formed through a single bone, the tunnel having a proximal end and a distal end located at opposing ends of the tunnel, the set of fixation devices comprising:
 an autograft or allograft; 
 a proximal fixation device interference screw configured to secure the graft autograft or allograft to cortical bone at the proximal end of the tunnel; and 
 a distal fixation device interference screw configured to secure the graft autograft or allograft to cortical bone at the distal end of the tunnel, wherein the distal interference screw is partially cannulated and has a back end with a surface disposed at an angle relative to a central axis of the interference screw. 
 
     
     
       9. The set of fixation devices of  claim 8 , wherein the proximal device has a tip with a rounded profile. 
     
     
       10. The set of fixation devices of  claim 8 , wherein the proximal device is fully-threaded. 
     
     
       11. The set of fixation devices of  claim 8 , wherein the distal device is partially cannulated and has a back end with a surface disposed at an angle relative to a perpendicular to a central axis of the fixation device. 
     
     
       12. The set of fixation devices of  claim 8 , wherein at least one of the distal device and the proximal device is an interference screw. 
     
     
       13. The set of fixation devices according to  claim 8 , wherein the proximal and distal fixation devices interference screws are configured to substantially occlude the respective opposing ends of the tunnel. 
     
     
       14. An interference screw for graft fixation, the screw having a fully-threaded outer surface, and at least one of a back end with a surface disposed at an angle relative to a perpendicular to a central axis of the interference screw and a front end having a rounded profile. 
     
     
       15. A method of securing a graft in a tibia during ligament reconstruction surgery, comprising the steps of:
 forming a tunnel through the tibia, the tunnel having an entrance at a tibial plateau and an exit at an anterior surface of the tibia;   extending a portion of the graft within the tunnel between the entrance and the exit; and   securing the graft within the tunnel by inserting, into the exit of the tunnel at the anterior surface of the tibia, an interference screw having a fully-threaded outer surface and a back end with an angled profile and a face disposed non-orthogonally relative to a central axis of the interference screw, the interference screw being turned during insertion so that the angled face of the back end of the screw is substantially flush with the anterior surface of the tibia, to wedge the graft directly against the tibia by the interference screw.   
     
     
       16. The method of claim 15, wherein the graft extends between the tibia and a femur, and replaces an anterior cruciate ligament. 
     
     
       17. The method of claim 15, wherein the interference screw is formed of a bioabsorbable material. 
     
     
       18. The method of claim 17, wherein bioabsorbable material comprises poly-(L-lactic acid).