Papers by Author: A. Szarek

Abstract: The paper present the analysis of metal prosthesis head stress state of hip joint endoprosthesis which is a result of variable loads during human motor activity and its influence on the erosion of materials. The analysis of stress state was made with use of FEM – ADINA numerical tool. The analysis of surface erosion process was made with use of the scanning electron microscope. To the researches was taken for heads from CoCrMo bearing shell and polyethylene UHMWPE.

Abstract: Commercially available acrylic cement which has been popular in orthopaedics in the nineties of the recent century (SIMPLEX P, manufactured by HOWMEDICA LIMERICK) was used in the study. The choice of this material was caused by the fact that the average period of operation of cement prostheses in human body amounts to ca. 12 years and large percentage of prostheses implanted in this period is destabilized in the bone. The investigations focused on assessment of changes in strength parameters of PMMA used in human body over a period of 10 years and their effect on prosthesis loosening. In order to determine differences in strength parameters of the cement, directly after polymerization and after a particular period of use in human body, a series of tests were carried out, aimed at determination of the effect of aggressive environment inside human body and fatigue load which results from human motor activity on changes in strength parameters in PMMA. PMMA samples (30 days after polymerization, stored in saline solution) and the samples removed from human body due to aseptic loosening were used for comparison of strength. Due to a very complex character of operation and specific load, were tested in order to determine the dynamic properties by means of DMTA method, thus to determine the storage modulus E’ and the mechanical loss factor tgδ, responsible for dispersion of mechanical energy.