Human Knee Biomechanics Modelling And Research On Biomechanical Characteristics Of Flexion Movement

This research is supported by NSFC (Natural Science Foundation of China), Key Project'Implanting prothesis's biotribological key basic research'and'Mechanical Virtual Human of China'. Based on reconstructed model of three-dimensional (3D) geometric knee including both bone and soft-tissue and the analysis of knee flexion motion, natural knee and post total knee arthroplastic knee three-dimensinal geometric models were built, the overall reconstruction precision of the 3D medical imaging of human knee bone was predicted. The models include femoral-tibial articulation, patella-femoral articulation and their bone, cartilage, meniscus and ligments. 3D registration combined with coordinate transformation technique was proposed and applied to investigate the relative flexion kinematics of the normal knee in vivo including stibio-femoral joint and patello-femoral joint. Dynamic finite element (FE) model of knee and post total knee replacement (TKR), which include tibio-femoral, patello-femoral articulations and the surrounding soft tissues, were developed in this research, to simulate both the kinematics and the internal stresses during knee flexion simulation. The biomechanical experimental system of knee flexion motion was set up to simulate human knee squatting using cadaver knees. The flexion motion and dynamic contact characteristics of knee joint and knee post TKR were analysed, and were verified by comparison with the data from cadaver in vitro experiment. Results showed that dynamic FE models of knee and knee post TKR are capable of predicting kinematics and contact stresses during flexion,and could be a efficient tool for the analysis of TKR and knee prosthesis design. Contents of this thesis are as following: (1) Three-dimensional bone and soft-tissue geometric knee and knee post TKR models. By the analysis of human knee anatomic structure impact on human biomechanical behavior, the main components of knee were included to be built as 3D geometric knee models.Quadriceps tendon, patella tendon, tibia collateral ligament, fibular collateral ligament, posterior cruciate ligament, anterior cruciate ligament, meniscus and femur, tibia, patella's cartilage were built in knee model. Commonly adopted TKR components (Sigma PFC) were modeled in this research. The Simulation resection and prosthesis assembly were carried out on the natural knee models. By above mentioned, the 3D geometric model of knee joint post TKR was established. Both of above models are relatively comprehensive and higher comparability models for the analysis of knee, TKR and knee prosthesis design.The overall reconstruction precision of the 3D medical imaging of complex surfaces human bone was evaluated by acquiring not only translational but also angular errors in three orthogonal directions between six orthogonal planes on machined bone segments. In this way, the error based on the identification of anatomical landmarks was avoided. This method can provide a reference for assessing the sensitivity, reliability and accuracy of human bone reconstruction.(2) The typical flexion motion-squating was measured by motion capturing system. The basic motion characteristics of knee flexion were obtained. Different models of several flexion knee positions were aligned to the same coordinate system by using the technique of 3D registration algorithm. Moreover, as for each model of the knee, an improved orthogonal object coordinate system was built on femur, tibia and patella. By establishing orthogonal coordinates on each part of the knee, the Euler angle coordinate transformation was applied to acquire data of knee relative flexion kinematics. In this way, 3D registration combined with coordinate transformation technique was proposed and applied to study the relative kinematics of knee.(3) A dynamic biomechanical experimental in vitro system of knee and knee post TKR flexion motion was established. This system was used to simulate human knee squatting using cadaver knee. Not only the synchronal measurement of both tibio-femoral and patello-femoral articulations but also the synchronal measurement of both kinematics and contact can be implemented in this experiment system. By comparing the results of cadaver knee flexion to those of FE model analysis, the effective degree of FE model analysis could be evaluated.(4) Dynamic finite element model of knee and post TKR, which include tibio-femoral, patello-femoral articulations and the surrounding soft tissues, were developed in this research, to simulate both the kinematics and the internal stresses during squat simulation. The kinematic simulating results and the contact stresses distribution of a full deformable contact analysis of knee and prosthetic knee joint during squat were verified by comparing to data from in vitro experiment. The established dynamic FE models of knee and knee after TKR could be used to predict the biomechanical characteristics of kinematics and the contact stresses during flexion. Not only the knee FE model but also the FE model of knee post TKR was esteablished. By using these established models, analysis of both tibio-femoral and patello-femoral articulations can be synchronal. Also, the synchronal biomechanical analysis of both kinematics and contact can be obtained.The three-dimensional geometric model of knee and knee post TKR including key bone and soft-tissue were built in this research. The motion of knee squat was measured and the relative movement of knee flexion was investigaed. A dynamic biomechanical experimental in vitro system of knee and knee post TKR flexion motion was established. Dynamic finite element model of knee and post TKR were developed in this research. The biomechanical characteristics of knee and knee post TKR flexion were studied. And the reference factors and the prediction of artificial knee joint design were discussed in this research. The established dynamic FE models and experiment system are capable of predicting the kinematics and the stresses during knee flexion,and could be efficient tools for the analysis of TKR and knee prosthesis design. Results of this research could be references for the research of knee pathology, rehabilitation and prosthesis design.