Construction and simulation mechanical analysis of dynamic knee joint finite element model based on CT image

Abstract

To construct a dynamic knee joint finite element model based on CT image data and verify the validity of the model. To provide a simulation model and basic data for biomechanical research of the knee joint by further finite element analysis. The CT data of a healthy male knee joint was selected. With the help of Mimics 19.0 and Hypermesh 12.0 software, a high simulation finite element model of knee joint was established following steps, including geometric reconstruction, reverse engineering, meshing and material characterization. The dynamic knee flexion model was generated by determining the boundary conditions and torque loading, and the validity of themodel was confirmed. The biomechanical changes of the tibiofemoral and patellofemoral joints under different knee flexion angles were analyzed by applying the loads (500 N) to the finite element model during knee flexion. A finite element model of knee joint was established based on CT images and anatomical characteristics. The model included three-dimensional elements such as bone, ligament, cartilage, meniscus and patellar retinaculum. The different finite element models of knee flexion states were produced by applying different torques after establishing boundary conditions. According to equivalent conditions (knee flexion 30 degrees, quadriceps tendon under 200 N stretch), the peak stress value of patella was 2.209 MPa and the average Mises stress was 1.132 MPa; the peak stress value of femoral trochlear was 1.405 MPa and the average Mises stress was 0.936 MPa. The validity of the model was proved by the difference between the model and previous studies of 1% to 13.5%. Dynamic model loading showed that the Mises stressof tibiofemoral joint decreased with the increase of knee flexion angle, while the Mises stress of patellofemoral joint was positively correlated with knee flexion angle. The Mises stress of cartilage stress planes at different knee flexion angles was significantly different(P<0.05). The finite element model established in this study is more comprehensive and can effectively simulate the biomechanical characteristics of dynamic knee joint, which provides support for further simulation mechanics researches of the knee joint.