Theoretical Comparison of the Methods of Surgical Treatment of Deforming Arthrosis of the Knee Joint

Comparison of the techniques of valgus osteotomy with resection osteotomy of the fibula in combination with sanitation arthroscopy. Resection of the fibula, debridement arthroscopy is characterized by minimally invasiveness, targeted therapeutic effect on the focus of destruction of the cartilaginous cover, removal of inflammatory mediators with abundant lavage, low-trauma intervention. Abrasive chondroplasty, subchondral tunneling during arthroscopy make it possible to create conditions for reparative processes, and the formation of hyaline-like cartilage in the defect zone. Corrective osteotomy may result in fractures of the tibial plateau, fractures of the cortical loop (instability of fixation), false joints, and fractures of metal structures.

Influence of Internal Defects of Basic Metal of the Equipment on Its Operational Properties

The paper deals with the issue of safe operation of technological equipment with a defect in the base metal of the delamination type. Mathematical modeling of the stress-strain state in the defect zone by the finite element method in ANSYS software package is carried out. The article presents and analyzes the obtained graphs of the distribution of stress intensity factors. Based on the analysis of the obtained dependences, it is shown that stratification of the base metal does not have a significant effect on the performance of the process equipment.

The Conformity of Rehabilitation Protocols Used for Different Cartilage Repairs of the Knee Joint—A Review on Rehabilitation Standards in German Speaking Countries

The present study analysed current rehabilitation protocols to investigate whether there is a standard for early rehabilitation after microfracturing (MFX), matrix-assisted cartilage transplantation (MACT), and osteochondral autograft transfer (OATS) of the knee joint in clinical routine, and if rehabilitation protocols differ in the repair technique used or the localization of the cartilage defect. The evaluation included rehabilitation criteria such as weight-bearing, range of motion, use of an orthosis, motion therapy, and rehabilitation training during the early rehabilitation phase after MFX, MACT, and OATS of the femorotibial and retropatellar joint space. We analysed 153 rehabilitation protocols after cartilage repair of the knee joint, including 137 protocols for after repair of the main weight-bearing (femorotibial) area and 16 for after retropatellar cartilage repair. Most of the protocols differed significantly according to the location of the repair and the procedure performed. Our findings indicate that full weight-bearing can be achieved significantly faster after MFX (5.6 weeks) and OATS (5.3 weeks) than after MACT of the main weight-bearing zone (6.6 weeks, p < 0.001). In addition, after retropatellar cartilage repair, patients are allowed full weight-bearing after 2.1 weeks compared to the main weight-bearing zone (5.3–6.6 weeks; p < 0.001). No standardized rehabilitation recommendations have been established. The present study shows that rehabilitation needs to be adjusted to the surgical technique and the location of the defect zone, and further investigation is warranted to establish standardized rehabilitation protocols after cartilage repair of the knee joint.

Shorting Resection and Correction of the Leg Length in the Treatment of Posttramatic Tibial Defects Complicated by Osteomyelitis

Background. Severe fractures of the shin bones are often accompanied by the formation of defects in the tibia, suppuration and soft tissue necrosis. In the case of surgical treatment of fractures, infectious complications reach 3.6-9.1%. One of the methods of treatment of infected defects is resection of the ends of the tibia with shortening. This operation has proven to be effective in the treatment of fresh fractures. The relevance of the work is due to the prospects of using this technique in the treatment of the consequences of fractures with the formation of infected defects of the tibia.Aim of the study. Improving the results of treatment of patients with post-traumatic defects of the tibia complicated by osteomyelitis by performing a shortening resection with simultaneous or sequential correction of the segment length.Material and methods. The results of treatment of 65 patients with diaphyseal post-traumatic tibial defects complicated by osteomyelitis were analysed. They were divided into 2 groups. Group 1 was formed by 31 (47.7%) patients, they underwent shortening resection of the ends of bone fragments in the defect zone with simultaneous lengthening at another level. Group 2 included 34 (52.3%) patients who underwent a shortening resection of the tibia without lengthening. In all cases, the Ilizarov apparatus was used as a fixator.Results. The technique for assessing the size of the true defect of the tibia was optimized taking into account the initial shortening of the segment and the distance between the proximal and distal fragments after resection of their ends. A treatment regimen was developed depending on the level of localization of the tibial defect, and the results of treatment of patients in the compared groups were assessed.Conclusion. Shortening resection is an effective treatment for patients with post-traumatic tibial defects complicated by osteomyelitis. Depending on the level of localization of the defect, it is advisable to carry out treatment according to one of two possible options. When the defect is localized in the upper and middle third of the tibia, shortening resection in an isolated form is shown. If the defect is localized in the lower third of the tibia, it is possible to supplement the shortening resection with an osteotomy in the upper third with Ilizarov lengthening.

DEVELOPMENT OF A BIODEGRADABLE MATERIAL FOR BONE REGENERATION BASED ON SILICON COMPOUNDS

In the course of this study we established that the laboratory sample in granulated form developed by us has a stimulating effect on the growth and proliferation of osteoblasts. Analysis of the data (CT, MRI) of the biological material obtained from the animals withdrawn from the experiment showed a statistically significant replacement of the artificial defect with bone tissue with signs of restoration of the cortical plate. The analysis of the CT results indicates that this method is sufficiently informative in assessing the regeneration of the trabecular structure of bone tissue. The study (MRI) of the bone material obtained from the animals participating in the experiment showed that when the osteoinductive material was integrated, the defect zone was replaced by 90%. In the projection of the defect, the newly formed tissue of a homogeneous structure was determined, corresponding in density to bone tissue with a high degree of mineralization. There was a complete restoration of bone tissue in the projection of the defect.

ASPECTS OF USAGE OF ORGANIC OR AQUEOUS BINDERS BASED ON III OR IV GROUP ELEMENTS OXIDES IN THE PRODUCTION OF CERAMIC MOLDS FOR CHEMICALLY ACTIVE ALLOYS CASTING (review)

The article considers the experience of using organic and aqueous binders based on silicon or aluminum oxides in the manufacturing of ceramic casting molds, and tendencies of world manufacturers in this industry to improve the quality, accuracy and operational reliability of cast products, especially critical parts made of titanium, intermetallic and heat-resistant alloys obtained by investment casting. The paper gives information on the results of studying physical and mechanical properties of ceramic molds and defect zone of the outer surface of castings made of various alloys.

CREATING OSTEOPLASTIC MATERIALS TO REPAIR JAW BONES DEFECTS

In the course of our research we have developed a technology for fabricating an osteoplastic material from natural bone tissue. The obtained preparation in the form of gel contains hydroxyapatite, calcium triphosphate compounds and stimulators for regeneration. The proposed experimental material produces a stimulating effect on the growth of animal cell types; it enables to produce bioactive materials with increased biocompatibility. Application of the experimental gel facilitates the process of bone-tissue regeneration in the laboratory animals, which, in its turn, confirms the optimal composition of the material. We have established that during the integration of our osteoinductive material the defect zone is completely replaced by the bone tissue.

Investigation of the nature of defects on the outer surface of heat-treated seamless pipes

Compliance with the quenching technology ensures a high-quality product with the required properties. Violation of the modes of heating for quenching and cooling during quenching leads to the formation of defects such as soft spots and quenching cracks. The presence of soft spots in the metal is unacceptable due to structural stresses and the difference in mechanical properties between the base metal and the defective areas. To remove soft spots, repeated heat treatment is required. Quenching cracks occur due to internal stresses that exceed the resistance to destruction, due to non-simultaneous transformations and thermal expansion and compression. Products with quenching cracks are the final rejects.The article examines soft spots and thermal cracks on the outer surface of seamless pipes formed during heat treatment. The results of metallographic studies of the microstructure in the defect zone are presented, and the genetic and morphological features of defects are determined and studied. The structural heterogeneity was confirmed by Rockwell hardness measurements. Based on the data obtained, the causes of defects were determined.

Analysis of the influence of residual stresses on possible defects formed during production of carbon-epoxy composites

В настоящей работе изучено влияние наличия остаточных напряжений в образце углерод-эпоксидного композита, сформировавшихся в процессе его производства, на такие возможные дефекты как межслоевое расслоение. Исследование посвящено анализу НДС в регулярных образцах вблизи зоны дефекта в течение цикла отверждения, а также при образовании свободного края в материале после разреза в зависимости от длины трещины. Для моделирования процесса отверждения решалась связанная тепловая и прочностная задача в условиях плоской деформации. Для описания поведения композитного материала в процессе производства, включая процессы формования, полимеризации, развития остаточных напряжений и деформаций, была разработана и реализована специальная пользовательская подпрограмма для ПО ABAQUS. В частности, в данной работе была проанализирована история величин скоростей энерговыделения в режимах раскрытия трещины по механизму нормального отрыва и поперечного сдвига в процессе полимеризации и последующего разрезания с образованием свободного края. Обнаружен незначительный рост значений GI , GII в вершине трещины в процессе полимеризации и многократное превышение этих значений после механического среза. В результате численного моделирования выявлено, что остаточные напряжения не оказывают существенного влияния на рост дефекта в композите на этапе его изготовления, но при приложении дальнейшей нагрузки на образец могут способствовать интенсивному росту расслоения. In the present study, the effect of presence of residual stresses inherited during manufacturing on delamination defect in carbon-epoxy composite specimen is investigated. The research is devoted to understanding of strain-stress state in regular specimens near defect zone during cure cycle and after free edge cut depending on crack length. To describe the behavior of the composite material during manufacturing process- including processes of formation, polymerization, development of residual stresses and strains, the special user subroutine was developed and implemented in ABAQUS FEM software. The history of energy release rates under mode I, II ( GIc , GIIc) where analyzed over time during process of polymerization and free edge cut. A slight increase in the GI and GII values at the crack tip during polymerization and a multiple excess of these values after a mechanical cut is shown. Obtained by modelling values for stress components are essential and cannot be ignored in consequent structural analysis. The results of the study can be applied for prediction of residual stresses in composite structure by means of simulation and further understanding the nature of fracture of composites.

Vibration Analysis of Deep Groove Ball Bearings With Local Defect Using a New Displacement Excitation Function

Bearings are vital parts of many mechanical equipment, the vibration signal analysis of bearings with local defects is important in guiding the fault diagnosis. In this paper, a dynamic analysis method is proposed to investigate the vibration response of the deep groove ball bearings (DGBBs) with local defect using a new displacement excitation function based on the Hertz contact theory and Newton's second law. The DGBB is modeled as a two degrees-of-freedom system, and an additional friction force in the defect zone, the influence of centrifugal force, the gravity of rolling elements, and lubrication traction/slip force between rolling elements and raceway are considered. And this model is used to study the dynamic signals of DGBB under different fault sizes and rotation speeds. Results indicate that the simulation signal has many continuous impacts and change over the time which is closer to the actual situation compared with the one-shot impulse function such as rectangular or half-sine or piecewise function when the rolling elements passed through the defect zone. Finally, the validity of the proposed model is verified by experiments. The simulated and experimental results indicate that the proposed model would achieve a more appropriate and accurate dynamic simulation.