Three-Dimensional Finite Element Analysis Of The Effect On The Biomechanics Of Internal Collateral Ligament,Lateral Collateral Ligament And Anterior Cruciate Ligament After Posterior Cruciate Ligament Rupture

Objective:Collect the normal image of CT and MRI scans of the knee, take advantage of the three-dimensional reconstruction and ANSYS three-dimensional finite element softwares to the establishment of dimensional finite element model of the normal human knee. On this basis, the simulation of three-dimensional finite element model of the posterior cruciate ligament (PCL) complete rupture (Ⅲ injury), calculate and analyze the normal knee model and the PCL complete rupture model of the stress distribution and changes of the medial collateral ligament (MCL), the lateral collateral ligament (LCL and the anterior cruciate ligament (ACL) to a comprehensive understanding of the PCL rupture it would affect the surrounding ligaments,which provides a theoretical basis for testing the importance of restoring the stability of the knee after PCL rupture.Methods:1. CT images and knee sagittal proton density-weighted (PDWI) images and cross-sectional, coronal and sagittal fat-suppressed T2-weighted images (T2WI) were obtained by using Spiral CT machine and Siemens1.5T superconducting magnetic resonance instrument,which were saved Dicom format to a working computer for bone, ligament, meniscus and articular cartilage layer boundary, in the period of import E-feature Biomedical Modeler software. Data obtained from the E-feature Biomedical Modeler software was digitized to DIP file, to obtain a three-dimensional spatial coordinates of the boundary of each level, and then finite element mesh, the definition of material properties, the model and the resulting knee dimensional finite element model, and then import it into the ANSYS finite element analysis software, the model for biomechanical analysis.2. A flexion moment at0°,30°,60°, varus/valgus and internal/external rotation torque were applied on the established three-dimensional finite element model of the normal knee, calculate and record the average stress and the equivalent stress distribution of PCL, LCL, ACL, MCL.3. In the established three-dimensional finite element model of the knee,the PCL was removed to analog PCL complete rupture (Ⅲ degree injury). The same mechanical analysis of the PCL complete rupture of the finite element model, the same calculate and record the average stress and the equivalent stress distribution of LCL,ACL, MCL, then compared with normal knee model and the statistical analysis.Results:The purpose of this study is to establish the three-dimensional finite element model of normal human knee and the model of the PCL complete rupture, the biomechanical analysis of the models. The results showed that:1. with the20N· m varus PCL complete rupture of the model LCL equivalent stress at different flexion average value (3.39MPa,12.41MPa,14.56MPa) than the normal group (2.30MPa,11.22MPa,12.84MPa) significantly increased;2. With8N· m external rotation torque PCL complete rupture model LCL equivalent stress at different flexion average value(1.34MPa,12.24MPa,12.56MPa) than the normal group (0.22MPa,10.10MPa,10.42MPa) significantly increased;3. with20N· m varus/valgus moment or8N· m internal/external rotation torque PCL rupture model of ACL and MCL of average equivalent stress compared with the normal group, the change of the stress is very small.Conclusion:1. A three-dimensional finite element model of normal human knee and the PCL complete rupture ware established. On this basis, biomechanical analysis of ligaments of human knee joint can put into practice. 2. Through the data comparison, it shows that LCL in the knee of PCL rupture varus and external rotation exercise stress increased significantly, ACL and MCL in knee of PCL rupture varus-valgus and internal and external rotation exercise stress change is small,For further validation PCL rupture should be reconstructed early to avoid LCL chronic injury.