The Research On Mechanical Behavior Of Articular Cartilage In Total Knee Joint During Standing And Riding

Knee joint is the hub of human lower limb movement,and it is also an important weight-bearing joint,which has the characteristics of load-bearing and physical activities heavy.So the knee joint becomes the predilection site of clinical disease.Once the cartilage lesions,people daily life will be affected seriously.The research has shown that the generation of osteoarthritis is closely related with the mechanical state of the knee joint,so it is necessary to further research the mechanical state of the knee joint under different gaits and the mechanics characteristics of the knee joint with lesions.The article studies the biomechanical characteristics of the whole knee joint and the knee joint with cartilage injury in standing(two legs and one leg)and riding(60°,80°and 100° flexion)and then make a comparison,in order to provide the theoretical reference for the prevention and clinical treatment of knee joint disease.In this paper,the finite element technique is used to evaluate the biomechanical characteristics of knee joint.Firstly,a model of the whole knee joint is established,which based on CT scanning,combined with the medical image processing software Mimics,reverse engineering software Geomagic Studio and the 3D drawing software Pro-e.This model includes the distal femur,proximal tibia,patella,fibula as well as their corresponding cartilage,meniscus,anterior and posterior cruciate ligaments,inter and lateral collateral ligaments and the patellar tendon.Then,the finite element model of whole knee joint and knee joint with an 8-mm diameter osteochondral defect are established respectively by Abaqus.In the implicit static module,boundary conditions and physical load are imposed on the finite element model so as to simulate and calculate the mechanical behavior of knee joint when standing.On the other hand,in the explicit dynamic module,boundary conditions of displacement and riding load are applied to the model of knee joint,to simulate and calculate the mechanical properties of knee joint in three phases of riding.The results show that the stress of cartilages and meniscus when standing on single leg is about doubled than that when standing on two legs.The 8-mm diameter osteochondral defect in femur cartilage generated maximal changes in von-mises stress(by 36.74%)when standing on single leg,the von-mises stress on tibia cartilage with 8mm defect increase by 87%.The distribution of the stress in cartilages is almost same when knee joint is standing,there is not obvious stress concentration in the defect.In the state of riding,the stress on the cartilage increases with the increasing flexion angles and the Von-mises stress increases by 71.25% from 60°flexion to 100°flexion.The stress distribution of cartilage is mainly located on the interior and posterior of tibiofemoral joint when the flexion angles increase,which may be closely related with the relative motion of femur and tibia.In addition,the mechanics characteristics of cartilage with injury in three phases of riding is investigated.It was found that the stress on the defect cartilage is larger than that of the healthy cartilage and the stress distribution of cartilage with defect is a little different from the healthy cartilage.In a summary,compared with standing on double legs,there is more stress generated when standing on single leg.High stress will be generated when riding in large flexion angle and cartilage injury is tended to cause the increase of the stress.Therefore,attention should be paid to protect the knee joint during daily exercise,once the articular cartilage is injured,it should be treated in time.