Development of a New Knee Endoprosthesis and Finite Element Analysis of Contact Stresses

In this paper, based on the virtual model of a classic knee prosthesis and on the clinical observations on the limitations of the range of motion of the prosthetic knee, the 3D virtual model of a new knee prosthesis is developed. This new prosthesis allows the development of lower contact stresses and an increase in the flexion-extension interval of the prosthetic knee. Finite element analysis (FEA) is applied in order to obtain the stress maps and the maximum von Mises stress obtained on the three components of the prosthesis and on the femur and tibia. Six models of prosthetic knee assembly were developed, obtained for three different varus angles and for both prostheses: the classic one (initial prosthesis) and the new one, (proposed prosthesis)). The results obtained lead to the conclusion that, with increasing varus angle, the von Mises stresses increase in each of three prosthetic components. Due to the curvatures and of added material in the new proposed prosthesis and due to the increase of the contact surface between the prosthesis elements, the contact stress decreases in the case of the new prosthesis compared to the classic one, which leads to improved biomechanics of the prosthetic knee.