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
This article studies several aspects of problems associated with diseases of big joints. It is an introductory essay to another three articles that focus on solving various biomechanical problems in hip joint. Stress limit states on contact surfaces of the hip joint can be considered as a common denominator of all these problems. General analyses of these states are described in a separate part of this article. Other general analyses concern the complex of problems associated with diseases of big joints. As an illustration (in view of the articles that follow), this article includes a systemic conception on analysis of the applicability of biomechanics in solving therapeutic problems of big joints. As an illustrative example, the hip joint was selected. and Obsahuje seznam literatury
This work presents the procedure of a computational model of pathological hip joint allowing a simple modification of individual parts of the model according to the planned course of femoral and pelvic osteotomy. Both presented models were subjected to strain-stress analysis by a finite element method using the ANSYS program system. The obtained results are compared with physiological hip joint results and the feasibility of planned osteotomy is evaluated based on selected mechanical parameters. The conclusions are consulted with surgeons and possible corelations with clinical results are searched for. and Obsahuje seznam literatury