Knee Sagittal Plane Elastic Contact Properties

Human knee joint is one of the biggest and most complex arthroses in the human body. Anatomically, it consists of femur, tibia, patella, various ligaments, meniscus and other soft tissue. There exist contact interactions in tibio-femoral and patello-femoral. In daily life, the knee joint is very prone to injury for supporting the weight of the human body and doing some three-dimensional movements like flexion, extension, etc. As one of the most important joint, the study of knee contact mechanism is helpful to understand the actual movement of the joint, analyze the stress during the movement, find the pathological mechanism of knee joint degeneration or damage, and thus guide the therapy of knee illness and artificial joint replacement.Based on the anatomical structure of the knee joint, a two-dimensional finite element model of a sagittal knee joint including tibio-femoral and patello-femoral joint is developed in ABAQUS/CAE. The elastic bio-contact response during flexion from 0° to 90° of natural and artificial human knee joints is investigated. The tibio-femoral bio-contact mechanical behaviors with or without articular cartilage and the effect of different replacement materials on the biomechanical behavior of the knee joint are studied. The numerical simulations show that the articular cartilage is a vital component of the human knee joint by providing a low friction, wear resistant contact surface and distributed stress for the tibia. The presence of a healthy articular cartilage is helpful to increase the contact line of the tibio-femoral joint and decrease the external moment and tibial pressure. For artificial knee joints, there is no correlation between tibial stress and femoral replacement material when the same replacement material of tibia and the same friction coefficient of the tibio-femoral bio-contact interaction is adopted. The artificial knee joint bio-contact mechanism is similar to that of the natural knee joint when the elastic moduli of femoral replacement materials approach to those of bones.