Vol 23, No 4 (2019)

Articles
ROLE OF PODOBAROMETRY IN THE ASSESSMENT OF PREOPERATIVE AND POSTOPERATIVE CONDITIONS OF PATIENTS WITH OVERLOAD METATARZALGIA
Slinyakov L.Y., Bogatov V.B., Rigin N.V., Bobrov D.S., Shubkina A.A.

Abstract

Surgical treatment of overload metatarsalgia is the actual problem, as this disease is subject to a large number of older patients. This contributes to the polyetiology of the disease. This article provides a comparative analysis of different types of surgical treatment of this pathology. The efficiency of surgical technique, which was supplemented by reinserting plantar ligaments of the metatarsophalangeal joint to the place of separation from the proximal phalanx of the finger compared to a classic small osteotomy of the metatarsal bones and phalanges. With the aim of evidence of the effectiveness of the proposed methods of treatment was used the method of podobarometry, which showed its effectiveness.
Russian Journal of Biomechanics. 2019;23(4):500-510
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MATHEMATICAL MODELLING OF EYE CORNEA DEFORMATION BY EXTERNAL PRESSURE
Moiseeva I.N., Stein A.A.

Abstract

The deformation of the eyeball under the effect of external pressure applied to the cornea in a limited area, for example, as a result of loading with an air jet, is considered. The cornea is modeled by a homogeneous, isotropic, momentless surface and, in the general case, is considered to be linearly Voigt-type viscoelastic. Its elastic properties are determined by the quadratic dependence of the strain energy on the components of the strain tensor, and viscous by the quadratic dissipative function of the strain rates. The scleral region is described by the differential relationship between the scleral volume and intraocular pressure.The process of slow deformation is considered in detail, when the derivatives of the deformation characteristics with respect to time can be neglected in the constitutive relations. It is shown that, at a certain external pressure, a section is formed in the central region of the zone of its influence, which can be considered to be flat with high accuracy. From the external pressure at which this zone occurs, the true intraocular pressure,i.e., pressure in an unloaded eye, can be determined with good accuracy. The relationship between these pressures is weakly affected by the elastic properties of both the cornea and the scleral region. In the area of external pressures corresponding to “flattening”, the rate of subsidence of the corneal apex at external pressure uniformly increasing changes. Possible generalizations of them ode land the problem formulation are discussed.
Russian Journal of Biomechanics. 2019;23(4):511-525
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BIOMECHANICAL PATIENT-ORIENTED ANALYSIS OF INFLUENCE OF THE ANEURYSM ON THE HEMODYNAMICS OF THE THORACIC AORTA
Skripachenko K.K., Golyadkina A.A., Morozov K.M., Chelnokova N.O., Ostrovsky N.V., Kirillova I.V., Kossovich L.Y.

Abstract

The aim of the study was biomechanical modeling of the development and influence of thoracic aortic aneurysm on the hemodynamics of the vessel. Aortic aneurysm is an irreversible expansion of the aorta and is one of the diseases of the cardiovascular system with a high fatal outcome. Biomechanical modeling included: setting the task, building a virtual model of the object under study, setting boundary and initial conditions and properties of materials, also assessment the results of a numerical experiment based on the physiological characteristics of the object. Two three-dimensional virtual models of the thoracic aorta were constructed on the basis of computed tomographic angiography of a real patient: with an aneurysm of the ascending division and after prosthetics. To analyze the development of pathology, were created additional virtual models with different degrees of aneurismal expansion. The calculation is carried out taking into account the parameters characterizing the work of the cardiovascular system (blood pressure value, dynamic viscosity and blood density). The analysis of the results showed a change in the character of blood flow, the formation of region of blood stagnation in the aneurysm zone. It was revealed that with the increase in the geometric dimensions of the pathology there is a drop in the blood flow rate and an increase in the flow pressure values in the aneurysm. Asymmetric distribution of pressure values on the inner surface of the aorta, triggered by the displacement of the flow velocity vector relative to the axis of the blood vessel, can to incite further development of an aneurysm.
Russian Journal of Biomechanics. 2019;23(4):526-536
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BIOMECHANICAL MODELING OF SURGICAL RECONSTRUCTIVE TREATMENT VARIANTS OF UNILATERAL SACRAL FRACTURES
Dol A.V., Ivanov D.V., Kazhanov I.V., Kirillova I.V., Kossovich L.Y., Mikityuk S.I., Petrov A.V.

Abstract

A comparative analysis of two surgical treatment variants for a unilateral longitudinal sacral fracture was carried out in three possible localization of the fracture line: outside the zygapophysis, inside and directly on the zygapophysis. Two variants of implants were considered: cannulated sacroiliac screws and a similar variant in combination with a bilateral lumbar-pelvic transpedicular structure. Analysis and selection of the most rational surgical treatment variant was carried out with the help of biomechanical and computer modelling methods. Surgical treatment variants were evaluated on the basis of investigated succes criteria. Finite-element modelling of static loading of the vertebral-pelvic complex segment was carried out. Displacements and equivalent stresses in bone tissues and implants were analyzed. From the biomechanical point of view, the installation of a transpedicular screws in combination with sacroiliac screws was the most rational variant of surgical treatment. This conclusion is valid for all simulated cases of the fracture line localization. The most unstable fracture variant was a one-sided longitudinal fracture of the sacrum passing through the zygapophysis.
Russian Journal of Biomechanics. 2019;23(4):537-548
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EVALUATION OF STRESS-STRAIN STATE OF THE FEMORAL ENDOPROSTHESIS COMPONENT WITH A NON-STANDARD CONE SIZE AND ADAPTER FOR ITS STANDARDIZATION
Zvereva K.P., Markov D.A., Golyadkina A.A., Polienko A.V.

Abstract

This paper presents the results of biomechanical modelling of the “femur-implant” system under condition of non-standard cone size and addition of the developed hip replacement adapter. One of the most effective treatment methods for diseases and injuries of the hip joint is total hip replacement. Expansion of indications for total hip replacement led not only to an increase in the percentage of implants, but also to an increase in the number of recorded complications. The leading position among complications is occupied by aseptic instability of the endoprosthesis components. With isolated reimplantation of the endoprosthesis cup and the friction pair “head-liner”, orthopedists are faced with the problem of non-standard sizes of the neck cone of the stem. This leads to the need for extraction of stable femoral components and a significant decrease in the effectiveness of the technique. To solve this problem, we developed an adapter, which is shaped as a truncated cone. The inner diameter of the adapter corresponds to the outer diameter of the non-standard cone, and the outer diameter of the structure has standard size. Biomechanical modelling methods were used to introduce this development into practical medicine. This paper presents stages of creating biomechanical models of the "bone-implant" system. Biomechanical modelling is carried out in the Ansys Workbench software. The main attention is focused on the distribution of equivalent stress values. Stresses occur in the metal structure elements with application of physiological loads. The maximum values of equivalent stresses in the structure under study at the load of 800 N (133.3 MPa) are comparable to maximum equivalent stresses in standard endoprosthesis structures, ranging from 31 to 195 MPa. The maximum values do not exceed yield strength of the material, which is 350 MPa. Thus, the results of biomechanical modelling showed high operational reliability of the developed adapter with a non-standard size of the femoral component’s neck.
Russian Journal of Biomechanics. 2019;23(4):549-556
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INFLUENCE OF AN ASYMMETRICAL LOAD ON GROUND REACTION FORCES DURING GAIT
Talar I., Hasiński K., Semmad P.-., Zagrodny B.

Abstract

Carrying loads asymmetrically can leads to pathological changes in musculoskeletal system or to its overload and injury. This work aims to show and analyze the distribution of ground reaction forces under the feet when an individual carries a load asymmetrically with different methods of carrying. The data were collected for young males. The values of forces were recorded on a pedobarographic force platform for 0%, 5%, 10% and 15% of the body mass and different way of carrying the load (backpack carried on one shoulder, cross body laptop bag, laptop bag held in one hand and laptop bag carried on one shoulder). This kind of carrying the asymmetrical load is most commonly observed on the university facilities. For all considered cases of asymmetrical loading, there were statistically important differences at the ground reaction forces in comparison to gait without any load. This indicates that wearing asymmetrical loading should be avoided.
Russian Journal of Biomechanics. 2019;23(4):557-565
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ERGONOMIC PROPOSALS FOR THE DEVELOPMENT OF ROBOT-ASSISTED GAIT TRAINING DEVICES
Žarković D., Šorfová M., Groleger-Sršen K., Ravnik D.

Abstract

Neurological gait disturbances require long-term gait rehabilitation. According to existing research results, robot-assisted gait training devices are designed to improve patient’s walking capabilities and to eliminate the operator's physical overloading. The aim of this paper is to present an ergonomic analysis of commercially available robot-assisted gait training devices, including both the operators and patients postures during robot-assisted gait training therapy. This ergonomics analysis was performed on the Hocoma’s Lokomat Pro, involving five randomly chosen device's operators and ten adult and children patients who received gait therapies on the day of the experiment. Both evaluators concluded that the most problematic points, from aspects of safety and fatigue for the operators, were the preparation process of the device, device adjustments to each patient individually, and the noise produced by the device. Subsquently patients mostly struggled with the device's ramp and uncomfortable harness. It was noted that although the Lokomat Pro is the most widely used robot-assisted gait training device with many advantages that contribute to improved patient ́s gait capacities, like in every medical device, there is always room for improvement. Research and development of robot-assisted gait training devices is a long-term process requiring multidisciplinary cooperation. The cooperation represents an enriching experience for a whole team of specialists and ensures that the product meets the criteria for the end-users.
Russian Journal of Biomechanics. 2019;23(4):566-578
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DISTRIBUTED CONTROL IN STABILIZATION OF A MODEL OF INFECTION DISEASES
Domoshnitsky A., Bershadsky M., Volinsky I.

Abstract

In this paper, we consider a model of infection diseases built by G.I. Marchuk in the form of system of ordinary differential equations. A distributed feedback control is added to achieve a stabilization in the neighborhood of a suitable stationary solution in the case where other methods do not work. An idea of a reduction of integro-differential systems to ones of ordinary differential equations is proposed. We study the exponential stability of a stationary point of the integrodifferential system.
Russian Journal of Biomechanics. 2019;23(4):579-585
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CLINICAL MARKERS OF FUNCTIONAL CONDITION OF RESISTIVE ARTERIES IN THE YOUNG MEN
Mantskava M.M., Momtselidze N.G.

Abstract

Research of resistive vessels, assessment of their functional state is one of the key issues of blood circulation from the point of view of physics, angiology, rheology, blood biomechanics and related sciences. The article examined some physical quantities that describe the functional state of resistive arteries. According to the results of our study, such physical components as the thickness of the intimal medial layer, the coefficient of resistance of the resistive arteries and Young's module turned out to be interesting pathophysiological markers that can reflect the change in the vascular wall at earliest stages, when there are no yet other precursors of the disease. It is very important to continue research in this direction in order to deepen, transport and generalize our data to large-scale cohort studies.
Russian Journal of Biomechanics. 2019;23(4):586-591
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THE STUDY OF BLOOD CIRCULATION AT EXPERIMENTAL TUMOR PARANEOPLASTICISM
Mantskava M.M., Nyashin Y.I., Lokhov V.A.

Abstract

The work is part of a joint project in which the authors investigated the blood circulation in experimental animals directly in the area of oncological cell transplantation and in the periphery by monitoring intensity of the local blood, hemolysis intensity, deformation of erythrocyte membranes and their aggregation. These values were compared with each other and with similar indicators of control animals. The results of the study were considered in the context of paraneoplasticism as the basic pathophysiological properties of the body to regulate, inhibit and not spread foreign cells. The authors plan to find a solution to the paraneoplastic reactions of the body using digital technology in conjunction with experimental data by mathematical modelling, transporting “paraneoplasticism” into the system of equations.
Russian Journal of Biomechanics. 2019;23(4):592-598
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NUMERICAL ASSESSMENT OF FATIGUE STRENGTH OF TRANSCATHETER MITRAL BIOPROSTHETIC STENT BASED ON THE TITANIUM NICKELIDE MODEL
Zhuravleva I.Y., Nushtaev D.V., Ardatov K.V., Sharifulin R.M., Afanasyev A.V., Bogachev-Prokofiev A.V.

Abstract

This study is devoted to assessing the fatigue strength of a self-expanding Nitinol frame for a prosthetic heart valve when reconstructing the conditions of primary implantation in the mitral position. The object of research is a stent-like supporting frame, which is a cellular structure that performs the function of the main fastening and maintaining the shape of the leaflets and cover. The study included two stages of the formation of the stress-strain state of the frame: the creation of a mathematical model that provides an assessment of the state of the structure of the support frame in the final state and an assessment of the fatigue strength. It is shown that during the packaging of the frame in the delivery system (compression), a high degree of localization of inelastic deformations leading to surface destruction of a number of cells and joints at the final stage of the compression process, is noted. In a number of cell vertices and frame junctions, the fatigue strength coefficient exceeded its limit value, which indicates their destruction under the influence of long cyclic alternating loads. The main effect on the fatigue strength of the structure is the stress-strain state obtained at the stages of compression and implantation. To meet the conditions of static and fatigue strength, a modification of the support frame structure is required.
Russian Journal of Biomechanics. 2019;23(4):599-612
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EXPERIMENTAL DETERMINATION OF THE MECHANICAL PROPERTIES OF THE PORCINE AREOLAR TISSUE
Shitoev I.D., Tverier V.M., Slovikov S.V., Wildeman V.E.

Abstract

In the literature, there are many examples and assumptions about the possible effect of dysfunction of the temporomandibular joint and general dental diseases on the state of a very important vascular artery, namely the internal carotid artery, the kinking and coiling in it, which can lead to the development of a stroke and ischemic disease of a brain. Nowadays, these diseases are one of the most frequent causes of severe disability and premature death of people. Unfortunately, at present there is no comprehensive explanation of influence mechanism of a person’s dentition on the damage of the vital vascular line that connects and unites the work of the brain and the heart. These discrepancies and contradictions can be eliminated after developing the biomechanical model of the influence of the temporomandibular joint dysfunction on the internal carotid artery. In order to correctly solve this problem, it is necessary to know the mechanical properties of the tissues located between the temporomandibular joint and the internal carotid artery. In this article, we selected the experimental technique, determined the theory that describes the behavior of the tissue in this experiment, selected and manufactured equipment, simulated the experiment in the ANSYS software package and compared the simulation results and theoretical calculation of the experiment. The simulation coincided with experiment with good accuracy, as a result the elastic modulus for areolar tissue E = 3 MPa was determined.
Russian Journal of Biomechanics. 2019;23(4):613-622
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NUMERICAL MODELING OF THE PROCESS OF ERYTHROCYTES AGGREGATION IN EXPERIMENT WITH MICROPIPETS
Kalyagina N.V.

Abstract

The numerical finite element method is proposed as a method to model the erythrocyte aggregation process. The results of the simulation of an experiment are presented in which hydraulic micropipettes were used to form a pair of erythrocyte aggregates in a dextran medium with a molecular mass of 150 kDa. The parameters of erythrocyte aggregation were determined: the value of pressure normal to the surface of erythrocytes, which attracts them; size of the contact zone; erythrocyte membrane strain energy; by comparing the results obtained experimentally and performed numerical simulation. The mathematical modeling of the erythrocyte aggregation process was performed taking into account shear stresses. The shear stress values were obtained using the Couette model and compared with the results of experiments on the separation of paired aggregates of erythrocytes.
Russian Journal of Biomechanics. 2019;23(4):623-637
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PERSONALIZED GEOMETRY DIGITIZATION TECHNIQUE OF THE VERTEBROMOTOR SEGMENT L4-L5 IN VIVO
Khoroshev D.V., Ilyalov O.R., Ustyuzhantsev N.E., Nyashin Y.I.

Abstract

The article aim is to present a technique for digitizing personalized lumbar computed tomography data into a finite element geometric model of the vertebromotor segment L 4- L 5 in vivo . The computer tomography images set digitization of the lumbar spine without pathological changes took place using Mimics Materialise . A total of 34 people were selected in the study, including 20 men and 14 women. The young patients’ age is ranged from 19 to 41 years. The article presents a technique for digitizing personalized data of computed tomography of the lumbar region into a finite element geometric model of the vertebromotor segment L 4- L 5 in vivo in Mimics Materialise . As an example, the technique application to obtain morphometric parameters of the vertebromotor segment L 4- L 5 in vivo on a finite element model is analyzed. The technique of digitizing personalized computed tomography data into a finite element geometric model in vivo can be used for any the spine segment.
Russian Journal of Biomechanics. 2019;23(4):638-646
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