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ACL Graft Placement Theory

Discussion

  • femoral tunnel
  • tibial tunnel:
  • isometric placement of ACL refers to the concept that a full range of knee can be achieved w/o causing long-term ligament deformation;
  • isometry can not exist because, during ROM, there is no one point on femur that maintains a fixed distance from a single point on tibia;
    • elongation always will occur;
    • placement of graft as closely as possible to centers of tibial & femoral attachments of anterior medial band┬áresults in least amount of strain (least change in length of ACL during complete ROM of knee);
  • many researchers have tried to determine which bundle regions of ACL are most isometric;
    • bone patellar bone grafts attempted replacement of anteromedial band of ACL, which is most nearly isometric portion of the normal structure;
    • of note, most surgeons feel that it is more important to replace the more non-isometric posterolateral band;
  • ACL graft should pull up into the tibial tunnel by about 2-3 mm with extension when fixed on the femoral side;
    • this represents the closest reconstitution of the ACL's "physiometry";
    • a graft that tightens (pulls up into tibial tunnel) w/ flexion will have a much higher likelyhood of failure and usually indicates a femoral tunnel too far anterior in notch.