Investigation into the analysis method for assessing contact stress in joint prosthesis

Contact stress is the important cause of wear and failure of knee joint prostheses implanted in the human body during movement. The calculation of contact stress on joint prostheses is often inaccurate due to the deviation of joint position during activity. This paper proposes a correction method for contact stress based on finite element results. Firstly, the contact stress and contact radius between femoral and tibial prostheses of knee joint were calculated and analyzed by Hertz contact theory. Then, individualized finite element models based on the individualized geometry of the joint prosthesis and individualized loading were constructed, and the finite element contact stress was analyzed. The finite element results were calibrated utilizing the Hertz contact theory. Additionally, this study investigated the impact of three gait patterns (normal gait, medial thrust gait, and bouncing gait) on the contact stress experienced by the tibial insert. The research methods and results can provide ideas for theoretical analysis and finite element simulation of prosthetic joint contact, as well as offer theoretical support and analysis methods for evaluating the lifespan of prosthetic joints.