EFFECTS OF THE ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTIONS ON THE STRESS DISTRIBUTION OF THE TIBIO-FEMORAL JOINT

Based on MRI images of the normal human knee, the normal, single-bundle and double-bundle ligaments reconstruction models of tibio-femoral joint were built. In the experiment, single load (axial force) and combined loads (axial force and torque) were applied to these models for the finite element simulation to obtain the stress distribution. Then we acquired stress distributions of the femur, tibia, articular cartilage, meniscus, posterior cruciate, medial collateral and the lateral collateral ligament to make a comparison between the stress distributions before and after the ACL reconstruction. The results show that: 1) The high-stress areas of the femur/tibia are located in the connection parts of the femur/tibia and ligament and the contact area between tibia and fibular. Meanwhile, the stresses on the tibia/femur after the reconstruction are close to those on the normal joint except for that the maximum stress in the junction between the femur and the MCL after single-bundle reconstruction under the combined loads exceeds that on the normal joint; 2) Single-bundle reconstruction can lead to the increment of the equivalent stress on femoral/tibial cartilages and the medial meniscus while double-bundle reconstruction lead to the increment on the femoral cartilage and the lateral meniscus; 3) Reconstructions have a greater impact on MCL; particularly, under the combined loads, there is a high-stress distribution in the middle and lower zone of the MCL. In summary, the increment of the additional stress after ACL reconstruction is the main reason for the chronic arthritis of the knee. As the tibia-femoral joint after double-bundle reconstruction are close to the normal joint in biological characteristics, we can make such a conclusion that double-bundle reconstruction is superior to single-bundle one.