Background: The sciatic nerve (SN) is the widest nerve of the human body that exits the pelvis through the greater sciatic foramen, usually below the piriformis muscle (PM), and descends between the greater trochanter of the femur and ischial tuberosity of the pelvis to the knee. The aim of this paper is to examine and identify the SN variations in relation to the PM, its prevalence, pattern, and course. Methods: A prospective-descriptive cross-sectional study was carried out to determine the frequency of anatomical variations in the exit of the SN in relation with the PM in 20 anatomical bodies (corpses) of both genders, in equal numbers. Results: The dissection of 40 SNs in corpses of both sexes in equal numbers showed that the SN exited inferior to the PM in 37 lower limbs (92.5%); between the fascicles of the PM and inferior to the PM in two lower limbs (5%); and in one thigh, between the fascicles of the PM and superior to the PM (2.5%). Our study reported that the SN divides in its terminal branches more commonly in the proximal part of the popliteal fossa in 55% of cases, in the gluteal region in 35% of cases, and in the middle third of the thigh in 10% of cases. Conclusions: Anatomical variations of the SN in relation to the PM are challenging for the diagnostic and therapeutic procedure in many clinical and surgical cases. Rapid recognition of the SN changes makes surgical approaches more accurate and effective. Our study confirmed that the SN exits the pelvis most commonly below the PM, although some anatomical variations may occur.

Objectives: Variations in the morphological anatomy of the median nerve such as formation, distribution, and communication have been well documented. All these variations should be taken into account when practicing any surgical approach for the treatment of injuries affecting the median nerve. Furthermore, they are of the utmost importance for interpretation of the clinical presentation. Methods: The objective of this investigation was to determine the anatomical variations in the formation of the median nerve in cadavers at the Forensic Pathology department in Central Clinical Hospital of the Academy of Sciences of the Russian Federation between January 2022 and April 2022. A descriptive, cross-sectional, and prospective information source study was conducted on 42 anatomical bodies (corpses) and 84 brachial plexuses. Results: After analyzing the results obtained in this investigation, we concluded that the median nerve presented variation in its formation in 22.6% of the investigated cases. These variations were more common in males (81.8%) than females (18.2%). The anatomical variation was unilateral in 7.1% and bilateral in 19% of all anatomical bodies examined. Conclusions: The median nerve presented a great number of variations in its formation in roughly 23% of the anatomical bodies, with male being the predominant gender. Furthermore, the most frequent region of formation was the axillary region (92.9%). For clinicians, it is important to remember these variations during surgical procedures in this area and during brachial plexus block.

BACKGROUND: Inflammation of the synovial membrane is a common manifestation in osteoarthritis which plays a role in complex pathophysiology of osteoarthritis. Synovitis leads to complications during knee replacement. AIM: To give clinical and morphological characteristics of the knee joint condition by histological assessment of the synovial membrane. MATERIALS AND METHODS: In the clinic of traumatology and orthopedics of North-Western State Medical University named after I.I. Mechnikov in 2022, 187 total knee arthroplasty operations were performed in patients with osteoarthritis. For morphological study of the synovial membrane of the knee joint biopsy specimens were taken from 30 patients (19 women and 11 men) by randomized sampling method. The age of patients: from 40 to 76 years, the average age was 59,3 ± 6,7 years. Immunohistochemical reactions were performed to characterize the cellular composition of the inflammatory infiltrate; antibodies to CD68, CD3, CD20, CD138, Ki-67 were used. Morphometry was performed at ×400 magnification. RESULTS: Only 48 (25.7%) patients had at least one course of inpatient conservative or minimally invasive surgical treatment for osteoarthritis of the knee joint before total knee arthroplasty. 18 (9.6%) patients had intraoperative and postoperative complications. Among 30 morphological studies conducted, 3 (10%) patients had verified stage I osteoarthritis of the knee joint, 8 (26.7%) were diagnosed with stage II osteoarthritis, and 19 (63.3%) — stage III osteoarthritis. Significant correlation was obtained between cells stained with antibodies to CD3 and CD20 (r = 0.69; p 0.05), CD68 and CD138 (r = 0.66; p 0.05). Cluster analysis identified three groups of patients with severe (10%), moderate (30%) and weak/absent infiltration (60%). CONCLUSIONS: To correct the treatment strategy for patients with osteoarthritis of the knee joint, it is advisable to strengthen the role of arthroscopic methods in the diagnostic and treatment processes.

This study provides a retrospective analysis of work to ensure high quality of medical care in an unfavorable epidemic situation. The consequence of COVID-19 was the implementation of a program to prevent the spread of infection, the re-profiling of medical institu-tions, and the introduction of restrictive and anti-epidemic measures. The experience of our work has shown the effectiveness of changing the order of med-ical care, the organization of the functioning of de-partments and patient routing. The study reflects the measures implemented in the hospital departments, the Department of clinical and laboratory diagnostics, radiation diagnostics and pathology Department. To ensure the safety of patients, it was decided to place patients on a single bed according to the type of infec-tious boxes. The safety of employees was ensured by the use of personal protective equipment, minimiza-tion of contact time with patients, and preventive weekly examination of staff for SARS-CoV-2 infection. The organized and well-coordinated work of the en-tire staff of the institution made it possible to prevent the spread of COVID-19 among employees, to detect cases of infection in a timely manner, and to carry out appropriate isolation and monitoring measures. At the time of completion of infectious diseases departments, the mortality rate among patients was less than 9%. Our experience in reorganizing a multi-specialty facil-ity can be used in the future when working with pa-tients who have undergone COVID-19, as well as in the context of a worsening epidemic situation.

Objective. To develop artificial intelligence-based software algorithm for quantitative assessment of reparative bone tissue regeneration, as well as to compare the results of histomorphometric analysis carried out by neural network and human. Material and methods. Morphometric parameters were determined and standardized. The authors developed artificial intelligence-based software algorithm with subsequent neural network training based on high-resolution images. Efficacy of human and software algorithm was compared. Results. Original software allows for automatic analysis of bone regenerate tissue composition within the shortest possible time. Conclusion. Original software may be equivalent for quick and effective analysis of bone regenerate tissue components. These data may be comparable with manual marking regarding reproducibility and accuracy.