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Background: Seven patients were subjected to intraoperative wake-up tests during reconstruction surgery of the anterior crucial ligament (ACL) to measure the tension of the reconstructed ligament., Methods: The patients were of 18 to 28 of age with ASA physical status 1. Anesthesia was maintained with nitrous oxide-sevoflurane-fentanyl or propofol-fentanyl under orotracheal intubation., Results: Patients anesthetized with nitrous oxide-sevoflurane-fentanyl did not perform smoothly in the wake-up test because of restless or delayed emergence from anesthesia, and two of them experienced intraoperative awareness. On the other hand, all patients anesthetized with propofol-fentanyl performed smoothly, and no patient experienced intraoperative awareness., Conclusions: Propofol-fentanyl is better than nitrous oxide-sevoflurane-fentanyl as the method of anesthesia for wake-up tests of ACL reconstruction surgery.

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.

The mechanical properties of a reconstruction of the anterior cruciate ligament (ACL) using an augmented substitute were investigated in rabbits' knees. After total resection of the ACL, 25 knees were reconstructed with a patellar tendon alone (nonaugmented group) and 25 with a patella tendon augmented by a Leeds-Keio artificial ligament (augmented group). The rabbits were sacrificed for biomechanical testing at 0, 4, 8, 12 and 24 weeks, respectively, after operation. In the augmented group, the mean ultimate load was 48.8% of the original ACL load at 4 weeks, and this gradually increased to 65.6% at 8 weeks. That of the twenty-four-week specimens was restored to 71% of the original ACL load. In the nonaugmented group, the mean ultimate load decreased to 9.3% at 8 weeks, but increased to 37.5% at 24 weeks. The mean static stiffness in the augmented group was higher than in the nonaugmented group at all time periods. The differences between the augmented and nonaugmented groups were statistically significant in the 8 to 12 week period (p < 0.01). Tan delta values, exhibiting the magnitude of viscosity in a viscoelastic material, in the augmented group were significantly higher than those in the nonaugmented group at 8 weeks (p < 0.05) and 12 weeks (p < 0.01). The mean tan delta in the augmented group decreased to 0.08 +/- 0.04 at 24 weeks, but the values were higher than those of the original ACL. The mean dynamic elastic modulus in the augmented group was higher than in the nonaugmented group at all time periods. The difference between the augmented and nonaugmented groups was statistically significant in the 8th week (p < 0.05). The values of dynamic elastic modulus in both groups were increased at 24 weeks: 96.4 MPa in the augmented group, and 77.5 MPa in the nonaugmented group. It was demonstrated that the augmented ligaments used for anterior cruciate ligament reconstruction had greater strength and static stiffness than the patellar tendon autograft. As for dynamic properties, the augmented group showed higher viscosity group than ACL.