It is well known now that COVID-19 can negatively influence different human body systems. Only few reports concerning avascular necrosis after COVID-19 have been accessible until now. The large-scale use of life-saving corticosteroids in COVID-19 treatment role is discussed in these papers. Four patients with bilateral avascular necrosis of the femoral head after being treated for COVID-19 infection are demonstrated. The doses of prednisolone used in three cases were 4000 mg, 746 mg and 533 mg. Сorticosteroids were not used for the treatment of one patient. Our data shows that the timing of the development of avascular necrosis after COVID-19 is significantly shorter than the terms of the osteonecrosis development in patients without COVID infection. Two patients out of four (sisters, 32 and 30 years old, 533 mg prednisolone dose and no corticosteroids) have burdened familial history (myocardial infarction, hypertension, thrombosis). Probably in these two sisters, hereditary vascular factors played some role in the genesis of avascular necrosis of femoral head. Further accumulation of evidence is needed to understand the characteristics of osteonecrosis after COVID-19. It is possible that several factors synergistically affect the development of this disease.

No abstract

Non traumatic osteonecrosis of the femoral head is one of the leading causes of hip function loss in young patients. At the late stages of this disease the only way to restore motor activity is total hip arthroplasty. Literature review presents the systematic analysis of the most significant causes of this disease (long-term intake of corticosteroids, alcohol abuse, thrombophilia). Pathogenetic mechanisms of femoral head vascularization disturbance are considered. In recent decades the fundamental genetic studies enabled to establish that pathogenesis of femoral head osteonecrosis is based on the polymorphisms of genes that ensure coagulation cascade, and angiogenesis disturbance.

621.762Microprobe analysis has been applied to the boundary layers between fibers and matrix to examine the phase composition in relation to mode of extrusion for composite materials based on iron and copper as reinforced with molybdenum and steel fibers. The width of the interaction zone varies from 2 to 4 µm.The phases correspond to the phase diagrams for these systems. Fractography indicates the failure mechanism for reinforced composites under conditions of stress and strain. At the points of application of shock loads, there is planar transverse fracture in the fibers by the cleavage mechanism. The peripheral layers are subject to viscous failure in the fibers with the formation of necks. Extrusion produces plastic strain uniform throughout the fiber length, and there are no breaks in the fibers, which provides conditions for complete realization of the strength of the reinforcing phase.

Relevance. Degenerative diseases of the spine are among the most common pathologies that cause significant medical, social and economic losses. Thus, a retrospective analysis of the Humana database from 2008 to 2014 indicates a sharp increase in discogenic neurocompression lesions of the cervical spine, which is 42 %. Degenerative processes are characterized by metabolic and structural changes in the intervertebral discs (IVD), which lead to the loss of its properties. The aim of the study was to analyze the results of intervertebral disc nucleoplasty and radiofrequency denervation of the facet joints in patients with cervical joint hernias. Materials and Methods . Intervertebral disc nucleoplasty and radiofrequency denervation of the facet joints in patients with hernias of the cervical spine was performed in 55 patients aged 18 to 74 years (mean age 36.28 ± 2.19 years), of which 56.36 % (31 patients) were men and 43.64 % (24 people) were women. Results and Discussion. The results demonstrate a significant improvement (p0.001) in VAS and ODI in patients after treatment. The majority of patients (45.45 %) rated their health status as “good”, 41.82 % of respondents believe that after the intervention, their health status can be assessed as “excellent”. Only 3 patients (5.45 %) indicated an unsatisfactory condition, which may be due to individual psychological characteristics, comorbidities, or a reduced sensitivity threshold. Conclusion. Nucleoplasty of the intervertebral disc and radiofrequency denervation of the facet joints is an effective and safe method for the treatment of intervertebral hernias of the cervical spine.