[Biomechanical study on the optimal running route for anterior cruciate ligament reconstruction].

The purpose of this study was to determine the isometric points for anterior cruciate ligament (ACL) reconstruction and to investigate notch impingement with isometric reconstruction. The length pattern of ACL was assessed by three-dimensional bi-plane X-ray photogrammetry for determining the isometric point for ACL reconstruction. The isometric points were studied in six fresh cadaveric knees with no injury in any ligament. Five femoral and four tibial attachment sites were selected for intra-articular reconstruction. In each knee, 20 different combinations were studied. For extra-articular reconstruction, three femoral and three tibial sites were selected. In these knees, nine different combinations were studied. One isometric point for intra-articular ACL reconstruction was a combination of the 5-mm superior posterior point from the femoral attachment of the ACL and the center point of the tibial attachment. The other was a combination of the anterior-proximal edge of the femoral attachment and anterior edge of the tibial attachment. There were no isometric points for extra-articular ACL reconstruction. To investigate notch impingement, eight cadaveric knees were studied. One femoral and three tibial attachment sites were selected. For the reconstructed ligaments, 8-mm and 10-mm cables were used. In each cadaveric knee, six different conditions were studied. When the tibial hole was positioned in the center of the attachment of ACL with an 8-mm graft, then notch impingement did not occur. When the tibial drill holes were positioned in a more anterior position, then notch impingement occurred in all the cadaveric knees in which an 8-mm graft was used. With the 10-mm grafts, notch impingement occurred in all three bony tunnel conditions. In these conditions, notch impingement occurred widely from the medial side of the roof to the wall of the lateral femoral condyle. Thus, if the graft diameter is greater than 8 mm, adequate notch plasty must be performed.