A Finite Element Analysis Of The Location Of Femoral Tunnel In The Anterior Cruciate Ligament Reconstruction And Its Affection On The Isometry Of The Graft

Objective:Establish a three-dimensional finite element model of the knee to analysis the accurate location of femoral tunnel in anterior cruciate ligament reconstruction and its influence on the isometry of the ligament graft.Method:Select a healthy volunteer and used Philips3.0T MRI to get successive scanning with layer thickness of1millimeter of the knee。The images were saved as a form of Dicom.Used the Mimics to built a three-diamensional geometric model of knee joint,which included the skeletons,cartilages,meniscus and ligaments, and optimized it in Magics9.9.Then imported the model into ANSYS and assign the mesh with specific materials attribute to establish a three-dimensional finite element.The femur attachments center points of anterior cruciate ligament were defined by anatomic description, four additional attachments points which were set as contrast were positioned at5mm proximal, distal, anterior and posterior to the center point.The tibia attachment point was placed on the center of the tibia anatomic attachment.Respectively load simulation on finite element model of knee applied different knee flexion, so as to investigate the length change of anterior cruciate ligament.Results:1.Based on Dicom document of MRI scanning, used software of ANSYS and Mimics,the study have established a finite element model of knee joint. The elements of the model included skeleton, cartilage,meniscus and ligament.2.This study demonstrated that the different positioning of the femoral tunnel had a significant effect on the properties of the graft isometric (P<0.01).The center of ACL femoral attachment has good isometric characteristics.The changes of reconstruction location within3mm, could also achieve physiologically equidistant requirements.It has been confirmed by LSD-t test that with the change of knee flexion angle, the distance of the center point and each control point to tibial attachment point were significantly different (P<0.01)。Conclusions:1. Using of reverse engineering software, finite element analysis software and MRI scan data, the finite element model of the knee was established.The model was simple and practical, and can simulate the human complex structures.2. In the process of ACL reconstruction, changing the position of the femoral tunnel positioning would bring a significant effect on the isometric characteristics of graft. In the case that the tibial tunnel has been accurately established, the closer the femoral tunnel district to the anatomical positioning of femoral ACL, the better isometric characteristics the ligament graft would get.