Russian Journal of Biomechanics

The aim of the study is to develop a new method for noninvasive determination of dynamic viscosity. In the developed method, the methods of mathematical modelling and the laws of rheology, mechanics, biomechanics and human physiology were used. It has been shown that an increase in blood viscosity leads to functional failure of various organs and tissues, disorders of the coronary and cerebral circulation. As a result of the analysis, it was revealed that blood can be considered as a colloidal suspension in which particles of erythrocytes and platelets are suspended, and the viscosity of such a colloidal system in microcirculation does not obey the Newtonian law. At the same time, the main factors that significantly affect blood viscosity include: blood pressure of hematocrit, platelet count, absolute amount of fibrinogen proteins and microglobulins, and lipoprotein concentration. A mathematical model has been obtained for determining the viscosity of the colloidal dispersed blood system, considering the concentration of the dispersed phase (blood cells) and the structure formation of blood; a model for determining the thickness of the boundary layer of blood corpuscles adsorbed on the inner surface of blood vessels is proposed and the mechanism of blood structure formation associated with the surface charges of erythrocytes and platelets is shown.

Conducting a gait analysis allows us to make an accurate diagnosis to document the progress of rehabilitation, as well as properly adapt the prosthesis to the patient. This study focuses on examinating the differences between a choosen healthy person (OZ) and a choosen person after an amputation (OPA) with enucleation in the knee joint in case of climbing stairs (ascent and descent). Two male volunteers of similar age (20-22 years) and height (180-185 cm) participated in the study. Biomechanical analysis was carried out using three prosthetic sets differing in knee joints (1. Blatchford Mercury, 2. Guardian, 3. Ottobock 3R80) and prosthetic foot (1. Össur Vari-Flex XC Rotate, 2. SACH, 3. Blatchford Elite 2). The staircase consisted of four steps (height 170mm, width 320mm). During the experiment, an optoelectronic motion capture system and force plate were used. Obtained results showed limited efficiency of ascending and descending stairs by OPA, compared to OZ. The most important difference between a healthy person and an amputee is their gait pattern, step-over-step and step-by-step gait, respectively. The value of the vertical component of the ground reaction force when climbing stairs is similar for both subjects. The analyzed parameters differ depending on the prosthetic set used by OPA. During the descent, the OPA can implement the step-over-step pattern, but only using the prosthesis set I (everyday use). Then, the forces acting on the sound limb during the stance phase are much higher than for OZ, which creates the possibility of overloading the given limb. The conducted biomechanical analysis draws attention to the importance of proper selection of the prosthesis for the patient.

One of the world trends of Industry 4.0 is the introduction of exoskeletal technologies into production processes. Manufacturers of industrial exoskeletons designed to reduce the negative impact of the work process on the human locomotive apparatus provide for the redistribution of the external load on the human body by means of various technical solutions. However, there is currently no uniform methodology for assessing the operational safety of exoskeletons. A significant biomechanical factor contributing to the safety of industrial exoskeletons as promising means of personal protection of the locomotor apparatus, is possibility to work without significant restrictions on the volume of movements. In this connection, the development of a methodology for objective quantification of the influence of structural and mass dimensions of industrial exoskeletons on the biomechanics of human movements is a topical task. This article presents the results of the measurements of the amplitude of movements in the large joints and joints of the spine, when performing the tests for flexion-extension, adduction-abduction and lateroflexion. The testing of volunteers was carried out on the clinical base of NII MT. The tests were performed both without the use of industrial exoskeletons (Group I) and with their application (Group II). The influence on the biomechanical parameters of volunteer movements by the structural characteristics of the industrial exoskeleton “Exochair” and two different models of the industrial exoskeleton “Exoatlant” was investigated. Parameters of movements of segments of the human body were measured with the help of inertial measuring sensors of the software and hardware complex “Biomechanika Trust-M”. Quantitative indicators have been identified which show the limitations of movements caused by the operation of different models of industrial exoskeletons. Thus, the use of the exoskeleton “Exochair” in deep seating limits the flexion in the hip joint by 67.1 %, in the knee joint by 56.1 %, in the lumbar thoracic spine by 61.9 %, and practically does not affect the flexion in the shoulder joint. The first model of the exoskeleton “Exoatlant” limits the amplitude of movements in the hip joint by 41.2 % at flexion and by 74.5 % at extension. At the same time, the second model limits the abduction of the shoulder joint by 20.5 %, and in the lumbar thoracic spine limits forward flexion by 17.3 %, rearward extension by 50.6 %, bending to the right by 46.4 %, and bending to the left by 40.3 %.

Surgery of the anterior cruciate ligament with its injuries is currently one of the most frequent in sports traumatology. There are many methods for its implementation, but one of the most frequent questions is the choice of a transplant to replace it. The graft must withstand loads comparable to an intact ligament. It is necessary to choose the most suitable human tissue for this purpose. This article discusses the biomechanical characteristics of the long tibial tendon as a graft for the anterior cruciate ligament. Our results allowed us to evaluate the mechanical properties of the graft obtained from the tendon of the long fibular muscle, to compare the data obtained with the available literature data describing the mechanical properties of the grafts used, and to show that the graft chosen for evaluation in this study is not inferior in its properties to those already used. The presence of a correlation between the graft diameter and the gender of patients suggests that further detailed statistical analysis will determine the possibility of accurate prediction of the graft diameter for high-quality preoperative planning.