Prosthetic reconstructions provide anatomical reconstruction to replace bones and joints. However, these operations have a high number of short- and long-term complications. One of the main problems in surgery is that the implant remains in the body after the operation. The solution to this problem is to use biomaterial for the implant, but biomaterial does not have the required strength characteristics. The implant must also have a mesh-like structure so that the bone can grow into the implant. The additive manufacturing process is ideal for the production of such a structure. The study deals with the correlation between different prosthetic structures, namely, the relationship between geometry, mechanical properties and biological additivity. The main challenge is to design an endoprosthesis that will mimic the geometric structure of bone and also meet the conditions of strength, hardness and stiffness. In order to match the above factors, it is necessary to develop appropriate algorithms. The main objective of this study is to augment the algorithm to ensure minimum structural weight without changing the strength characteristics of the lattice endoprosthesis of long bones. The iterative augmentation process of the algorithm was implemented by removing low-loaded ribs. A low-loaded rib is a rib with a maximum stress that is less than the threshold stress. Values within the range (10, 13, 15, 16, 17, 18, 19 and 20 MPa) were taken as the threshold stress. The supplement to the algorithm was applied to the initial structure and the designed structure at threshold stresses σ_f = 10, 13, 15, 16, 17, 18, 19 and 20 MPa. A Pareto diagram for maximum stress and the number of ribs is plotted for all cases of the design: original, engineered and lightened structures. The most optimal was the designed “lightweight” structure under the condition σ_f = 17 MPa. The maximum stress was 147.48 MPa, and the number of ribs was 741. Specimens were manufactured using additive manufacturing and then tested for four-point bending.

The quality of modern measuring instruments has a strong influence on the speed of diagnosing diseases of the human musculoskeletal system. The research is focused on automatization of the method of gait analysis. The study involved six healthy subjects. The subjects walk straight. Each subject made several gait types: casual walking and imitation of a non-standard gait, including shuffling, lameness, clubfoot, walking from the heel, rolling from heel to toe, walking with hands in pockets, and catwalk. Each type of gait was recorded three times. For video fixation, the Vicon Nexus system was used. A total of 27 reflective markers were placed on the special anatomical regions. The goniometry methods were used. The walk data were divided by steps and by step phases. Kinematic parameters for estimation were formulated and calculated. An approach for data clusterization is presented. For this purpose, angle data were interpolated and the interpolation coefficients were used for clustering the data. The data were processed and four cluster groups were found. Typical angulograms for cluster groups were presented. For each group, average angles were calculated. A statistically significant difference was found between received cluster groups.

The simulation of the stress-strain state of porous media is actual problem nowadays. The application of the mathematical apparatus of continuum mechanics to such media will make it possible to extend the scope of the problems to be solved. In this paper we study method of determination of mechanical properties in representative element bases on computer tomography data. To this task algorithm to create finite element grid connected with the data of the computed tomography was developed. Orthotopic properties can be determined by using target function. Unknown components of the target function are orthotropic directions. These directions can be determined by minimization of the target function. Rotating the matrix of anisotropic constants leads to components of the orthotopic tensor in orthotopic axes. These tensors are compared using of stress invariant.

The development of additive manufacturing technology leads to new concepts for design implants and prostheses. The necessity of such approaches is fueled by patient-oriented medicine. Such a concept involves a new way of understanding material and includes complex structural geometry, lattice constructions, and metamaterials. This leads to new design concepts. In the article, the structural design method is presented. The general approach is based on the separation of the micro- and macro-mechanical parameters. For this purpose, the investigated region as a complex of the basic cells was considered. Each basic cell can be described by a parameters vector. An initializing vector was introduced to control the changes in the parameters vector. Changing the parameters vector according to the stress-strain state and the initializing vector leads to changes in the basic cells and consequently to changes in the microarchitecture. A medium with a spheroidal pore was considered as a basic cell. Porosity and ellipticity were used for the parameters vector. The initializing vector was initialized and depended on maximum von Mises stress. A sample was designed according to the proposed method. Then, solid and structurally designed samples were produced by additive manufacturing technology. The samples were scanned by computer tomography and then tested by structural loads. The results and analyses were presented.

The development of composite materials and products with a complex internal structure poses questions to develop experimental methods to determine the stress-strain state. Standard experimental methods do not provide a broad picture of the internal changes in the inhomogeneous samples under loading. Moreover, a presence of internal defects, porosity, local buckling can significantly effect on the obtained results. Despite the development of tomography and data processing methods most studies are performed without any external loading on sample. The research presents a methods for studying the porosity of samples under uniaxial compression using an X-ray computed tomography. For this purpose, special equipment that allows loading the sample inside the tomography was made. Additionally, a methodology was developed. The equipment allows not only to transfer the axial compression force, but also to measure the corresponding load value. The equipment was designed to reduce artifactual rays in a place where studied sample mounted. To determine the reference points under loading, a contrasting copper grid was used. A modified Harris detector was used to quantify the displacements. The displacements of the reference points were interpolated to a regular initial grid to estimate the displacements inside the sample. Test samples were designed and manufactured using additive technologies to illustrate the methodology. A series of loadings and tomography scans were carried out for each sample. The tomography data were processed according to the methodology. As a result, the displacement fields of the samples, the values of porosity, volumetric strain and their distribution over the sample for each loading step were obtained.