The Biomechanical Three-dimensional Finite Element Analysis Of The Effects About Posterior Cruciate Ligament Rupture On Lateral Collateral Ligament

Objective The purpose of this study is to establish three-dimensional finite element model of healty human knee including the posterior cruciate ligament (PCL) and lateral collateral ligament (LCL) with a set of consecutive MRI images and three-dimensional finite element software(ANSYS software). In this model,the PCL was removed to simulate its injury of gradeâ…¢.Then we calculated and analyzed the stress distribution and-variation of LCL both in the normal knee model and PCL injury ones. Based on this,we want to fully understand whether the injury of PCL will affect the biomechanics of LCL,which is one of the important structure of posterolateral corner(PLC), whether LCL will have secondary injury for compensating some loss function of PCL,so as to provide theoretical guidances for the clinical diagnosis and treatment of both PCL and LCL injury.Methods MRI images of a normal male volunteer's knee jiont (including sagittal proton density-weighted images(PDWI),cross and sagittal fat-suppressed T2-weighted images(T2WI)) were obtained using Siemens 1.5 Testla high field superconducting magnetic resonance. Then saved these images into the computer workstation. Using 3D-DOCTOR software obtained the boundary of every structure of the knee jointat at a set of consecutive MRI images and digitized these data(IGS file) before importing the data into ANSYS software. According to the model building principle from point to line to area to volume of ANSYS software, a three-dimensional model of the knee joint was reconstructed on the basis of the images of MRI.By meshing every part in the three-dimensional model,a three-dimensional finite element model of healty human knee was established.A flexion moment, varus/valgus torque and internal/external axial torque were applied on the established three-dimensional finite element model of the nomal knee,to mimic flexion of normal knee at 30 degrees and 60 degrees, varus/valgus movement, internal/external rotation movement, calculate and recorde the average stress and the equivalent stress nephrogram images of PCL, LCL, ACL and MCLIn the established three-dimensional finite element model of the normal knee,the PCL was removed to simulate its injury of gradeâ…¢. A flexion moment,varus/valgus torque and internal/external axial torque were aslo applied on the PCL injured model. Then calculated and recorded the average stress and the equivalent stress nephrogram images of LCL, the peak Von Mises Stress(VMS) of femoral attachment and fibula attachment of LCLResults A three-dimensional finite element model of healty human knee was successfully established, and PCL's injury of gradeâ…¢was also successfully simulated. The data of biomechanical analysis using these two models confirmed the following discoverise: 1. PCL and LCL can do something to prevent the knee varus and external rotation movements.2. The average stress of LCL is lager in the nomal model than in the PCL injured ones when knee joint do varus and external rotation movements, which had statistic significance(p<0.05). However, there is no deference of the average stress of LCL between the nomal model and the PCL injured one when knee joint do valgus and internal rotation movements(p>0.05).3. The peak Von Mises Stress(VMS) of femoral attachment and fibula attachment of LCL is lager in the nomal model than in the PCL injured ones when knee joint do varus and external rotation movements (p<0.05). Compared the added value of the peak VMS of the fibula attachment and the femoral attachment, we found that the former is grater than the latter (p<0.05).Conclusion 1. A three-dimensional finite element model of healty human knee, which can reflect anatomical structures and simulate a variety of motion of human knee joint was reconstructed using MRI images and ANSYS software. On this basis, biomechanical analysis of ligaments of human knee jiont can put into practice.2. PCL's injury of gradeâ…¢was also successfully simulated using the established model.3. We confirmed that PCL and LCL can both prevented varus an external rotation of the knee joint using three-dimensional finite element method.4. We confirmed the LCL would have a secondary damage due to the injury of PCL. The damage usually take place in the flexion, varus and external rotation situation, and injuries often occur in the fibula attachment.