Finite Element Analysis and Comparison of Stress Distribution in Cartilages and Meniscus of Two Healthy and Varus Knee Specimens

In a varus knee, the load balance on two sides of the knee joint is disturbed and the stress applied to the medial side of the joint will be greater than that of a healthy knee. Such a case is often progressive and gradually leads to wear and pain. In this study, the finite element model for two 3D samples of healthy knee joint and varus knee in normal standing position was generated from MRI images and after loading and solving the problem, the stress distribution status in menisci and cartilage is obtained for both modes. The obtained results show the difference in maximum stresses and the difference in the shape of stress distribution areas. The results also show that the maximum values of von Mises stress and also the contact pressure in the inner area of the knee for the varus knee are much higher values compared to a healthy knee. In the standing position, the maximum contact pressure in the inner area of the joint, under a 400 Newtons load applied to the upper end of the femoral head, was obtained 4.527 and 7.821 MPa for a healthy knee and varus, respectively. For maximum values of von Mises stress, 2.821 and 6.501 MPa was obtained respectively.Due to the results and differences in stresses, the need for surgery to balance the stresses and loads on two sides of the knee is essential for a patient with varus knees. The amount of correction can be determined in addition to examining the joint geometry by examining the differences in stresses on both sides of the joint in a more accurate way.