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
The presented work is focused on the biomechanical study of the dental disk implant. The first part of the study deals with the strain analysis of the affected bone tissue and the dental implant loaded in the coronoapical direction by force 190 N. The study includes three types of implant anchorge, four degrees (stages) of osseointegration and nine degrees describing the quality of the cancellous bone. Two types of the disk implant were researched: single-disk and double-disk implant. Biomechanical study of the implant was focused on a stress-strain analysis of the affected bone rissue. The highest influence on the stresses in the bone tissue was primarily an implant anchorage. By the application of correlation relationships between Young modulus and the apparent density of the bone tissue - which is measurable in patients - we achieved the variable presented in this study. and Obsahuje seznam literatury
The presented work follows the first part [1], which is focused on the analysis of bone tissue in terms of dependence of bone tissue 'quality' and its subsequent behaviour based on the stress around the disk implant when biting.
This second part is focused on the stress-strain analysis (and tolerability) of disk implants as loaded during the masticating process.
The study includes two types of disk implants (single-disk and double-disk), three types of anchorage, four degrees (stages) of osseointegration in three quality degrees of the cancellous bone. The study, as expected, has shown that the problematic area of he implants is a transition between the implant body and the disk component, where the equivalent stress in the analyzed implants reaches 700 MPa. and Obsahuje seznam literatury
This article deals with determining the size of linear wear of acetabulum of total hip endoprosthesis by experimental modelling. The creation of an experimental sample and the equipment to simulate human walking are described in detail. The greatest attention is paid to the method form determining the topography of polyethylene cup and measuring of the loss of polyethylene during the simulation of walking. Holographic interferometry was selected to determine the loss of polyethylene cup on the basis of extensive analysis. Further parts of the article focus on first experience with the application of this method results and other possibilities. 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
The paper is focused on computational modeling of elbow articulation with radial head replacement. The main part of the project is aimed towards the creation of computational model of suitable partial endoprothesis of proximal part of the radial bone tissue which would keep the function of the elbow articulation while replacing the distance created by resection. The geometrical and computational models of radial head replacements and elbow joint were created. Computational models with these implants were compared with given physiological state of elbow articulation. The influence of friction and material characteristics of bone tissue and cartilage on changes in contact pressure (and therefore to the abrasion) were analyzed using those models. and Obsahuje seznam literatury
This review deals with the stress strain analysis of the normal tibio-femoral joint in its basic position (extension). On the basis of the analysis, a contact pressure between a femoral and tibial cartilage and femoral cartilage and meniscus has been obtained. The geometry of bones (tibia and femur) was described by computer tomography and the shape of cartilage and meniscus was created with the aid of literature [1], [3], [16]. The system was loaded by displacement. Following the Ansys analysis, force representing the load within the knee joint area has been determined. and Obsahuje seznam literatury
In case of a traumatological contusion of the elbow joint the bearing surfaces of the proximal end of the radius are damaged or broken off, resulting in their surgical removal. This operation does not make the elbow connection non-functional; however, it results in shortening the antebrachial bones, causing unpleasant pain in the patient‘s wrist. The medical team of the Traumatological Hospital in Brno has asked us to come up with a partial radio-humeral alloplasty, eliminating such adverse effects.
The presented paper is focused on the stress-strain analysis of the restored tooth. For this problem computational modelling was chosen using the finite element method. The tooth is modelled from dentin and dental enamel with a class II cavity. The size of the dental cavity is considered in three sizes and three shapes. For restoration two types of filling materials were used. A physiological model of the tooth was created as well. Force was prescribed on the occlusal surface of the tooth. The analysis of results shows that from the different filling materials, and their interaction with the dental tissues, amalgam is from a mechanical aspect the best material for the restored tooth in the molar segment. 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