• Smart Structures and Systems
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• v.17 no.1
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• pp.107-122
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• 2016

We propose an effective methodology using electromechanical impedance characteristics for estimating the remaining tensile force of tendons and simultaneously detecting damages of the anchorage blocks. Once one piezoelectric patch is attached on the anchor head and the other is bonded on the bearing plate, impedance responses are measured through these two patches under varying tensile force conditions. Then statistical indices are calculated from the impedances, and two types of relationship curves between the tensile force and the statistical index (TE Curve) and between statistical indices of two patches (SR Curve) are established. Those are considered as database for monitoring both the tendon and the anchorage system. If damage exists on the bearing plate, the statistical index of patch on the bearing plate would be out of bounds of the SR curve and damage can be detected. A change in the statistical index by damage is calibrated with the SR curve, and the tensile force can be estimated with the corrected index and the TE Curve. For validation of the developed methodology, experimental studies are performed on the scaled model of an anchorage system that is simplified only with 3 solid wedges, a 3-hole anchor head, and a bearing plate. Then, the methodology is applied to a real scale anchorage system that has 19 strands, wedges, an anchor head, a bearing plate, and a steel duct. It is observed that the proposed scheme gives quite accurate estimation of the remaining tensile forces. Therefore, this methodology has great potential for practical use to evaluate the remaining tensile forces and damage status in the post-tensioned structural members.

• Journal of the Korean Arthroscopy Society
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• v.9 no.2
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• pp.222-231
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• 2005

Purpose: This article describes a double-bundle ACL reconstruction technique using a five-strand hamstring tendon autograft with conventional anteromedial bundle reconstruction and additional posterolateral bundle reconstruction. Operative technique: For the tibial tunnel, the conventional single tunnel technique is performed and for the femoral tunnel, the double tunnel technique is performed with the anteromedial and posterolateral bundle. After minimal notchplasty, the anteromedial femoral tunnel is prepared with leaving one milimeter of posterior femoral cortex within the over-the-top, which if positioned at the 11-o'clock orientation for the right knee or at the 1-o'clock position for the left knee. The posterolateral femoral tunnel that is located 5 to 7 mm superior to the inner margin of the lateral meniscus anterior horn at $90^{\circ}$ of flexion is prepared with tile outside-in technique using a 4.5 cannulated reamer. The graft material for the double bundle reconstruction is made of the conventional four-strand hamstring autograft in the anteromedial bundle and of a single-strand semitendinosus tendon in the posterolateral bundle. The anteromedial bundle is fixed with using a rigid fix system on the femoral side and the posterolateral bundle is fixed to tie with the miniplate from the outside femur. Then, with the knee in $10^{\circ}\;to\;20^{\circ}$ of flexion, a bioabsorbable screw is simultaneously applied to achieve tibial fixation with tensioning of both bundles. Conclusion: A double bundle reconstruction with five-strand hamstring autograft, which is designed with a favorable conventional anteromedial bundle and an additional posterolateral bundle to restore rotation stability, seems to be a very effective method for the treatment for ACL instabilities.

• Journal of the Korean Arthroscopy Society
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• v.6 no.2
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• pp.195-199
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• 2002

This article is to report a new technique for reconstruction of the anteromedial and posterolateral bundles of anterior cruciate ligament by separate tensioning and fixation of the each bundle. Method : Tibial and femoral tunnels were made with conventional technique of anterior cruciate ligament reconstruction. Tibial tunnel was enlarged $5\~7$ mm in anterior-posterior direction to make oval it in cross section. When preparing the Achilles tendon allograft, bone plug portion was trimmed as the conventional technique. The tendinous portion was trimmed as two separate bundles by dividing the tendinous portion longitudinally, so the graft is shaped like 'Y'. The bone plug portion of allograft was inserted into the femoral tunnel and fixed with absorbable cross pins. Two ligamentous portionss of the distal part of the grafts were tensioned separately at the external orifice. Anteromedial bundle was fastened under maximum tension with the knee flexed 90 degrees by post-tie method. The posterolateral bundle was fixed by the same technique with the knee in full extension. Then, an absorbable interference screw was inserted between the two bundles upto the upper end of the tibial tunnel, to get more initial rigidity of the reconstructed graft as well as to locate the two bundles in more anatomic position.