Knee Joint Edoprosthesis - Verification of Contact Pressures by Pressure Sensitive Films

Abstract — Common total knee endoprosthesis (TKE) consist of a metal femoral component and a tibial component (an UHMWPE plateau and its metal tray). Though metal in case of the femoral component can be replaced with the more progressive material like Zirconia [1] (the endoprosthesis developed with a contribution of our Laboratory of Biomechanics) a loading remains unchanged. For future development of actual endoprosthesis, a quality FE model seems to be a key-goal. While developing a dynamic model [2] of a lower limb focusing on the knee joint with the implanted endoprosthesis, every partial result is being verified. One of the most important characteristics of the endoprosthetic system using the UHMWPE plateau is contact pressure between the plateau and the femoral component. For the mechanical test serving for verification of contact pressures (formerly calculated by FEA) by means of pressure sensitive films, special jigs were designed for the femoral and the tibial component and the measurement up to 3000 N were made. Then using the single-purpose software, magnitudes and a distribution of a contact pressure were calculated and compared with FEM results. Since a geometric model of the endoprosthesis and a factory-made endoprosthesis seem not to be identical in shape of contact surfaces, a result comparison was very hard. Based on a position of a contact and its area we beg to conclude that the results are very promising.