In endoprosthesis surgery there are typically a high percentage of implant defects, these can lead to failure of the whole prosthesis. One type of total hip replacement function loss is acetabular cup loosening from the pelvic bone. This article examines manufacture perturbations as one of the possible reasons for this kind of failure. Both dimension and geometry manufacturing perturbations of ceramic head and polyethylen cup were analyzed. We find that perturbations in the variables analysed here affect considered values of contact pressure and frictional moment. Furthermore, contact pressure and frictonal moment are quantities affecting replacement success and durability. From obtained results we can recommend to fit head and cup with a clearance of between 0 mm andd 0.05 mm. We do not recommend using interference type of fit. Roundness perturbation of ceramic head should not exceed 0.025 mm. and Obsahuje seznam literatury
Possibility of substituting the affected hip joint with endoprothesis is - for many people all over the world - the only way for returning to the normal life without pains and significant motion limitations. But the age limit requiring the application of replacement becomes lower and lower. The endoprothesis applied to young patients must be replaced several times during their lives and the application and repeated replacements affect the bone so that it may happen that the next application may not be possible any more. For such cases the surface replacement the propose of which is to postpone the need of the first application of the classic total endoprothesis, has been invented. So that the objective of the contribution consists in creating a computing model of the healthy hip joint and the hip joint with the classic total hip replacement and with the surface replacement, in carrying out the stress-strain analyses, and in mutually confronting the results obtained. The problem has been solved as a direct task by means of computational modelling, by the method of finite elements in the ANSYS. The computational model consists of these components: sacral, pelvic and femoral bone, muscles, cup, and femoral compponent. and Obsahuje seznam literatury