Finite element simulation of hip joint replacement under static and dynamic loading

The objective of this work is to develop methods for the structural analysis of orthopaedic implants. The central argument is that, if stress distributions are interpreted in the context of failure models of the component materials, significant advantages can be made in our ability to design these devices. The artificial hip joint is used throughout as an example. The finite element method was used as a structural analysis tool and its pplicability was discussed. Validity and accuracy were assessed and results were ompared with previous experimental and finite element studies. By comparing tress distributions with failure criteria for prosthesis and cement, the suitability of roposed design changes were assessed and guidelines for materials selection were resented. Prediction of bone stresses were also given for different prosthesis designs n the region of the artificial hip joint where bone adaption contributes to failure. hereafter the focus was on utilizing a new technique to develop a new hip prosthesis model. This study was divided into two parts according to the loading type. In this regard the stress field in the artificial hip components (prostheses, cement mantle, and bone) is analysed statically and dynamically to assess the implant longevity. In this static analysis all the simulations were conducted by assuming the peak loads during the normal gait at a particular time (static loads). The aim was to study the effects of a set of variables within which an optimal prosthesis design can be made by means of finite element analysis to qualify and quantify the stresses and the strains in natural and treated human femur for different cases of implantation. Until now, models developed to predict stresses in total hip replacements have been generally poorly validated. This could be because all the pre-clinical simulations were performed statically, that is by selecting the greatest load at a particular time of the activity cycle. The second part of the study was aimed to take into consideration, in designing total hip replacement, another factor belongs to the patient activity (stamping, jumping, walking, etc) and the effect of impact over the prosthesis head during these activity into the prosthesis performance. This study considered the prosthesis hip deformation with time, dynamic loads study. The elimination of impact cracking was considered by studying the effect of using “damper” trapped between the grooved prosthesis collar and the bone. Material selection of the total hip replacements was also investigated under the dynamic loading. The approaches of prosthesis fixation have been studied, too. This study was conducted by onstructing three-dimensional finite element model for a femur implanted with a cemented prosthesis with a representative physiological loading condition by using he LS-DYNA3D software