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.

Avascular necrosis (AVN) of the femoral head is a disease, characterized by the death of osteocytes and bone marrow, leading to collapse of the femoral head and dysfunction of the hip joint. There are many known risk factors for the development of this disease including trauma of the hip joint, hemoglobinopathy, alcoholism, taking corticosteroids, collagenosis, etc. Conservative treatment (drug therapy using vascular drugs, bisphosphonates, chondroprotectors, NSAIDs, physiotherapy, exercise therapy) is shown for any stage of the hip AVN, however, surgical treatment has a higher potential. The key to successful treatment is the detection of AVN at an early (pre-collapse) stage to prevent subsequent collapse by performing organ-sparing surgical interventions that reduce the rate of disease progression and allow delaying of the hip replacement. The literature describes a number of organ-preserving operations performed at an early stage of AVN. Currently, there are three main areas of surgical treatment of this disease: classical decompression of the femoral head, decompression using various types of grafts and combined treatment using various cellular technologies. This literature review is devoted to the consideration of the indications for implementation, as well as the results of treatment of patients using the above techniques.

BACKGROUND: There is no consensus on the methods of surgical treatment of early stages of avascular necrosis (AVN) of the femoral head. Decompression of the necrotic zone in different variations is the most widely used, but the effectiveness of it is debated. AIM: We evaluated the effectiveness of classic decompression of the necrotic zone and decompression using a percutaneous expandable reamer combined with bone graft. MATERIAL AND METHODS: Fifty patients were included in our study. The inclusion criteria were decompression of the necrotic zone in AVN of the femoral head at stages III and the possibility of assessing the effectiveness of surgical treatment after 12 months. Depending on the method of decompression, the patients were divided into two groups. Group 1 included 25 patients who underwent decompression using a percutaneous expandable reamer combined with bone graft. Group 2 consisted of patients who underwent classic decompression of the necrosis area. The groups were comparable in all major clinical characteristics. The efficacy of surgical interventions was assessed after 12 months by comparing pre- and postoperative assessment of the functional state of the hip joint using the Harris Hip Score and the intensity of pain syndrome using the visual analog score (VAS). The main criterion for ineffectiveness of AVN decompression of the femoral head was the need for total hip arthroplasty. RESULTS: Twelve months after surgical treatment of femoral head AVN, group 1 patients average Harris Hip Score was 63.9, group 2 patients average Harris Hip Score was 74.1 (versus 59.1 and 63.9 before surgery, respectively); VAS was 2.7 in both groups (versus 5.5 and 4.8 before surgery, respectively). Three patients (12%) from group 1 and four patients (16%) from group 2 underwent total hip arthroplasty, to persisting pain syndrome and progression of osteonecrosis of the femoral head to the subchondral fracture stage. The differences between the groups were statistically insignificant. CONCLUSION: Decompression of the necrosis zone is an effective method of treatment of stages I and II of AVN of the femoral head, significantly reducing the intensity of pain syndrome and slightly improving the functional characteristics of the hip joint. Studies in this direction should be continued with the involvement of more profiled patients and with the analysis of the effectiveness of other joint-preserving surgical techniques.

Introduction. Among the etiological factors of non-traumatic avascular necrosis of the femoral head are the following: the prolonged use of corticosteroids, alcohol abuse, systemic lupus erythematosus, sickle cell anemia, the Legg Calve Perthes disease, ionizing radiation, cytotoxic agents, etc. At the same time necrosis of the femoral head might occur in the absence of the above factors (idiopathic necrosis). The reasons for idiopathic avascular necrosis could be a mechanical obstacle to the flow of blood, thrombotic occlusion of vessels, extravascular compression. The purpose of this study is to examine the role of C677T gene mutation of the MTHFR gene in the development of non-traumatic avascular necrosis of the femoral head. Materials and methods. During this study there was a comparative analysis of the frequency of the C677T gene allelic variants conducted in 41 patients with a verified diagnosis of non-traumatic avascular necrosis (main group) and 320 healthy individuals (control group). The survey program included the study of polymorphisms of MTHFR C677T gene by PCR. Results. Differences in the frequency of occurrence of C allele of C677T gene MTHFR in the heterozygous state in case of non-traumatic avascular necrosis and in its absence were not statistically significant (51.2% against 37.2% respectively, 2 = 3.014, p = 0.083). The genotype TT (T in the homozygous state) of the C677T MTHFR gene was detected in 19.5% of the main group patients. A similar index in the control group was two times lower and amounted to 9.0 percent, the differences between groups statistically significant, 2 = 4.314, p = 0.038. Conclusion. The study showed the importance of having the T C677T MTHFR gene in the pathogenesis of non-traumatic avascular necrosis of the femoral head. The data obtained and the analysis of the current literature suggests that this polymorphism is one of genetic predictors of non-traumatic avascular necrosis of the femoral head and other cardiovascular diseases as well.

BACKGROUND: Nowadays total hip arthroplasty (THA) is the method of choice for the treatment of late stages osteonecrosis of the femoral head (OFH) and osteoarthritis (OA) of the hip joint. OBJECTIVE: To evaluate the efficacy and complication pattern of THA in late stages of OFH and OA. MATERIALS AND METHODS: The study included 74 patients who underwent primary THA for OA stages IIIIV (Kellgren and Lawrence classification) and for OFH stages IIIIV (ARCO classification). Group 1 included 34 patients with OFH stages IIIIV, and group 2 40 patients with OA stages IIIIV. The groups were comparable by gender and age. All patients underwent implantation of endoprosthesis components using press-fit fixation with a metalpolyethylene articulation. Treatment results were assessed with regard to the incidence of complications and functional results at 3, 6 months, 1 and 3 years after THA. RESULTS: In our study, the survival rate of components after THA within 3 years after implantation was 100%. No cases of periprosthetic fracture, periprosthetic infection, and aseptic instability of endoprosthesis components were observed in both groups. The surface inflammation of the postoperative wound was detected in 1 (2.9%) patient in the OFH group and in 1 (2.5%) patient in OA group. Dislocation of the endoprosthesis occurred in 1 patient with OFH; there were no such findings in the OA group. The frequency of peri-implant osteolysis was twice lower (2.5%) in patients with OA compared to OFH group (5.8%). There were no statistically significant differences in the functional results dynamics before and after surgery between the groups (Harris score). The average Harris scale score in patients with OFH was 63 and reached 94 after 3 years; in OA group 58 and 94, respectively. CONCLUSION: THA is an alternative method in the treatment of severe hip arthroplasty. Endoprosthetics using a cementless endoprosthesis with a metalpolyethylene articulation demonstrated high efficacy as well as a low number of complications among patients with OFH and OA. We found no significant difference in THA results in terms of survival, postoperative complications, and functional outcome in patients with OFH and OA. Longer postoperative follow-up is advisable, which may allow us to establish some differences in treatment outcomes.