This work examines a biomechanical system consisting of the hip endoprosthesis and bones of the pelvic region of a person under a load corresponding to the equilibrium of a person in double-supported state. An assessment of the strength of a customised endoprosthesis has been carried out based on the analysis of the stress-strain state of the finite element model of the "skeleton-hip prosthesis" system when tightening the screws and when the system is subjected the person's weight; dangerous areas of the pelvic bone with high level of stresses have been identified. As recommendations, optimization of the location and number of screws used in order to create a more uniform stress distribution is proposed.

The aim of this paper is to investigate and compare the stress distribution of a reconstructed pelvis under different screw forces in a typical walking pattern. Computer-aided design models of the pelvic bones and sacrum made based on computer tomography images and individually designed implants are the basis for creating finite element models, which are imported into ABAQUS software. The screws provide compression loading and bring the implant and pelvic bones together. The sacrum is fixed at the level of the L5 vertebrae. The variants of strength analyses are carried out with four different screw pretension forces. The loads equivalent to the hip joint reaction forces arising during moderate walking are applied to reference points based on the centres of the acetabulum. According to the results of the performed analyses, the optimal and critical values of screw forces are estimated for the current model. The highest stresses among all the models occurred in the screws and implant. As soon as the screw force increases up to the ultimate value, the bone tissue might be locally destroyed. The results prove that the developed implant design with optimal screw pretension forces should have good biomechanical characteristics.

The article contains a biomechanical assessment of the performance of a customized endoprosthesis of the hip joint. Finite-element models of the hip bone and the implant in the projected and actual positions are prepared. The article provides the results of the static structural analysis for a patient in the two-leg standing position in the post-operative period. The results are compared for various implant positions. As a recommendation, it is proposed to optimize the location and the number of screws for a more uniform stress distribution.

This study presents a model for Ti6Al4V alloy produced by applying electron beam melting as continuum media with orthotropic elastic and plastic properties and its application in total hip replacement (THR). The model exhibits three Young’s moduli, three shear moduli, and three Poisson’s ratios as elastic properties and six coefficients describing the Hill yield criterion. Several uniaxial tension and torsion experiments and subsequent data processing were performed to evaluate the properties and coefficients. The typical values obtained for Young’s moduli, shear moduli, and Poisson’s ratio were 121–124 MPa, 37–42 MPa, and 0.25–0.26, respectively. A comparison of the experimental tension and torsion curves with those obtained by a finite element analysis revealed a good correlation with a maximum error of 9.5%. The finite element simulation of a personalised pelvic implant for THR manufactured from the obtained material proved the mechanical capability of the implant to successfully withstand the applied loads.

Current article is devoted to the application of computer-aided engineering technologies to the virtual testing of customized endoprostheses of large joints. The research is performed for a representative case, where the personalized prosthesis of the hip joint is used as a part of the process of treatment of osteosarcoma, as conventional systems are not applicable. The study is highly relevant due to the intensive development of personalized medicine allowing for the patients’ successful recovery and mobilization. However, since each of the customized implants is a unique part, a rapid, accurate and financially efficient methodology of performing the structural analysis of such components is required to avoid the real testing of each implant. The article describes the all steps of the structural simulation of the series of loading scenarios for the biomechanical system consisting of the pelvis and endoprosthesis. The process of preparing the finite element models of pelvic bones and components of the implant is also explained in detail. The stress-strain state of the pelvis and implant is investigated for a number of values of the pretension force of the screws. Based on the comparative analysis, a set of practical recommendations is formulated to reduce the stress in the bone tissue. The discussed steps are the elements of the methodology of the rapid finite element virtual testing of the customized implants that is currently developed by the research group.