Introduction Periprosthetic infection (PPI) is a serious challenge for orthopedic surgeons. Two-stage revision with an antibiotic-impregnated spacer is one of the most common methods for treating periprosthetic infection. Purpose To evaluate the functional results of the second stage of revision arthroplasty in patients with PPI and to determine the survival of the endoprosthesis components. Materials and methods We retrospectively studied the results of the second stage of treatment (removal of the spacer and installation of the endoprosthesis) in 23 patients admitted to the department for the period 2016–2019. All patients received a spacer during the first stage of treatment. The mean age of the patients was 53.7 ± 2.2 years. Males prevailed (91.3 %). Results Three patients developed infection recurrence in the follow-up period of 44.4 ± 1.9 months. The effectiveness of revision arthroplasty performed as the second stage of treatment was 87 %. The Harris Hip Score before the second examination was 42.3 ± 2.5 points, at the time of the last follow-up examination it was significantly higher, 78.32 ± 3.8 points (p = 0.000052; Z – 4.04). Discussion The success of two-stage revision arthroplasty is influenced by the factors associated with patients’ co-morbidities, pathogenicity of the pathogen identified at the first stage, as well as the features of the implants used and surgical tactics. Conclusion The second stage of revision arthroplasty in patients who received a spacer with an antibiotic for the treatment of periprosthetic infection at the first stage significantly improved their functional state. The Kaplan-Meier implant survival rate was 77.5 %. 

The objective was to determine most common pathogens causing periprosthetic joint infection (PJI) of major joints, to identify the tendency to antibiotic resistance over the period from 2015 to 2020. Material and methods Microbiological culture results of 354 patients with PJI of major joints treated at our department were retrospectively analyzed. The spectrum of the leading pathogens causing PJI and the antibacterial resistance were explored and the prevalence of common organisms depending on the type of PJI demonstrated. Results 354 patients were examined and 317 microbial isolates identified. Gram-positive bacteria was isolated in 70.7 % (224 microorganisms) of cases, Gram-negative bacilli isolated in 28.1 % (89 organisms) and Candida sp. identified in 1.2 % (4 isolates). Microbial associations were identified in 15% of cases. Discussion Most common pathogens causing PJI included S. aureus identified in 31.9 %; S. epidermidis, in 20.2 %; E. faecalis, in 8.5 %; P. aeruginosa, in 7.9 %; A. baumannii, in 7.3%. PJI associated MRSE strains increased from 12.1 % to 26.7 % and S. haemolyticus (MR) increased from 2 % to 11.6 %. S. aureus and Gram-negative bacilli were most common for early acute and hematogenous acute PJI. There were no significant differences in the prevalence of S. aureus and S. epidermidis in early/delayed and late chronic PJI. Enterococcus species and Gram-negative bacilli were detected less frequently with PJI. There was an increasing antibiotic resistance of A. baumannii and P. aeruginosa. Vancomycin-resistant strains and linezolid-resistant strains were newly found among Grampositive bacilli and pan drug-resistant A. baumannii strains. Conclusion The six-year microbiological monitoring showed S. aureus, S. epidermidis, P. aeruginosa, and A. baumannii as most common pathogens causing PJI. The growing antibiotic resistance of Gram-positive and Gram-negative bacilli and the increasing role of the latter in the pathogenesis of early acute PJI require changes in empirical antibiotic therapy regimens.

Purpose To study the most common gram-positive microflora and its antibiotic sensitivity in chronic osteomyelitis over a three-year period. Materials and methods The microbiological study included 5,226 clinical isolates of gram-positive microorganisms belonging to 6 taxa (S. aureus, S. epidermidis, S. saprophyticus, Enterococcus sp., Streptococcus sp., Corynebacterium sp.), detected in the period from 2017 to 2019 in primary cultures from wounds and fistulas of 5,116 patients with chronic osteomyelitis who were treated in the purulent department of our bone infection clinic. Results and its discussion According to our study, S. aureus strains are most common g gram-positive microflora in chronic osteomyelitis, taking the first place in terms of occurrence over a three-year period. The rate of isolation of methicillin-resistant strains of S. aureus (MRSA) over three years was 17.3 ± 1.9 %. In 2019, the occurrence of S. epidermidis strains increased by 28 % compared to 2017, while the number of isolated MRSE remained within 57.2 ± 1.8 %. The analysis of antibiotic patterns showed a tendency to an increase in the number of multi-resistant strains of Staphylococcus sp. Monitoring of the gram-positive microflora in chronic osteomyelitis revealed an insignificant isolation of the bacteria of the genus Enterococcus and Streptococcus (9–10 % of cases). The most effective against Enterococcus strains were glycopeptides and aminopenicillins, the least effective against strains of Enterococcus were quinolones and aminoglycosides. The most effective drugs against Streptococcus sp. were levofloxacin and clindamycin. The occurrence of bacteria of the genus Corynebacterium sp. was within 3–4 %. The least effective drugs against Corynebacterium sp. were clindamycin, gentamicin, and ciprofloxacin. The strains were susceptible to tetracycline drugs, penicillins, macrolides and rifampicin. Conclusions Considering that gram-positive microorganisms are primary pathogens in the etiology of chronic osteomyelitis, microbiological monitoring of the leading pathogens of the disease and their resistance enables to identify ineffective antibacterial drugs, optimize treatment, and thereby reduce the rate of poor outcomes in the management of the disease.

Introduction The use of laboratory tests to monitor the treatment of patients with chronic osteomyelitis has a lot of clinical relevance. The purpose of the study was to identify laboratory tests for assessing metabolic processes in patients with purulent lesions of the foot bones for monitoring the dynamics of the recovery processes in the course of treatment. Methods The studies were carried out in 36 patients with chronic osteomyelitis of the calcaneus and adjacent bones of the foot of traumatic etiology. All patients were treated with the method of the Ilizarov transosseous osteosynthesis. Biochemical and coagulation parameters were studied. Results It was found that in patients with purulent lesions of the foot bones, the elevated levels of blood serum lactate were most frequently detected before surgery (52.8 %, 95 % CI: 36.6-68.6). The incidence of elevated CRP was 27.7 % (95 % CI: 14.6-43.3) on average, and one third of patients had elevated fibrinogen levels (33.3 %, 95-CI: 19.1-49, 3). During the treatment period, the incidence of elevated lactate levels in patients did not change but the incidence of elevated CRP levels increased significantly which was observed in 77.8 % of patients on the 3rd post-surgery day. By discharge from the hospital, elevated values of CRP and lactate occurred in 11.1 % of patients. It is assumed that the greatest diagnostic significance is the assessment of the level of lactate in the dynamics of the treatment in target patients. Discussion Based on the results of the studies, a laboratory sign was found that indicates the effectiveness of surgical treatment in patients with chronic osteomyelitis of the foot bones using the method of transosseous osteosynthesis. Such a sign is a decrease in the initially elevated concentration of lactate in the blood serum of patients in the postoperative period. The detected sign meets the requirements for its applicability in laboratory tests: 1) this sign is the most common in the target group of patients; 2) the dynamics of changes in the level of lactate correlates with the ongoing treatment; 3) this test is an indicator of a significant physiological process: oxidative metabolic processes in patients with the studied pathology.

Introduction As the demand for joint replacement increases over time, the number of concurrent complications such as periprosthetic joint infection (PJI) will also increase. Surgical approaches in carbohydrate metabolism disorders (CMD) remain under-explored. Epidemiological and pathogenetic aspects of the metabolic status of patients with PJI and disorders of carbohydrate metabolism must be examined prior to revision total hip replacement. The objective was to identify statistically significant differences in blood serum biochemical parameters in patients with PJI of the hip joint in groups of patients with and without carbohydrate metabolism disorders. Material and methods The blood serum of 76 patients with PJI of the hip without a history of carbohydrate metabolism disorders and 56 patients with PJI of the hip and CMD as a concomitant pathology was examined. Patients had a history of diabetes mellitus and impaired glucose tolerance. Obesity, a preclinical form of CMD, was determined by calculating the body mass index (BMI > 30). Serum C-reactive protein (CRP), bilirubin, glucose, urea, total protein, albumin and globulins, creatinine, aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured using an automatic biochemical analyzer ILab Aries and BioSystems reagent kits. The measurements were compared using generally accepted methods of variation statistics. Results C-reactive protein and globulin levels were increased (the albumin-globulin coefficient was not within normal limits) in patients with PJI. Fasting glycemia, urea and creatinine showed significant differences in patients with CMD as compared comparison with those in no-CMD patients. Reliable excesses of the measurements do not, however, deduce them beyond the limits of normal values. Discussion Our findings indicate preclinical renal changes in patients with PJI of the hip and CMD.

Introduction Literature data and analysis of our own material indicate a change in the density of the long bone cortical plate in patients with chronic osteomyelitis along its extension; however, the nature and degree of structural disorders of the cortical layer beyond the inflammation zone is an unexplored area of radiomorphology. Objective To study the structural features of the cortical plate of the femur and tibia outside the inflammation nidus and the change in its structure in the form of trabecularization. Material and methods The study is retrospective single-center work of level of evidence IV. In 86 patients with chronic osteomyelitis of the long bones of the lower extremities, using polypositional radiography and multislice computed tomography (MSCT), the features of radiological morphology of the femur and tibia were studied in order to identify structural features and quantify the density of the cortical plate and its trabecularization. Results The cause of the inflammatory process in the bone in 83 cases was trauma or surgery, and consequences of hematogenous osteomyelitis in three cases. The most common location of chronic osteomyelitis was the distal femur (24) and tibia (25) bones. Due to long-term disease, nonunion or a bone defect developed in 11 patients. Analysis of MSCT data in 86 patients with chronic osteomyelitis showed that anatomical changes in the femur and tibia and the density characteristics of the cortical plate near the focus of destruction were manifested in 79.5 % of patients with a decrease in the thickness of the cortical plate (up to 2 mm) with complete trabecularization in separate areas with density from 290 to 360HU in 47.7 % of the examined. Conclusion Radiological morphological changes in the cortical plate of the femur and tibia in patients with chronic osteomyelitis near the focus of destruction were characterized by a decrease in the thickness and density of the cortical plate, accompanied by its complete or partial trabecularization with a density not exceeding 315.5 ± 38.6 Hounsfield units (HU) in 41 ( 47.7 %) of 86 patients.

Introduction It is known that the density of the cortical plate of long bones in patients with chronic osteomyelitis changes throughout its extension. However, the nature of structural disorders in the cortical layer outside the inflammation zone has not been studied well. Purpose To study the structural features of the cortical plate of the femur and tibia outside the focus of inflammation to identify microcavities and microabscesses. Material and methods The study is retrospective conducted at one center. Evidence level IV. In 92 patients with chronic osteomyelitis of long bones of the lower extremities, using polypositional radiography and multislice computed tomography (MSCT), the features of radiological morphology of the femur and tibia were studied in order to reveal structural features of the cortical plate and identify microcavities. Results The cause of osteomyelitis in 5 cases was a consequence of hematogenous osteomyelitis, and in 87 cases it developed due to trauma or surgery. The most common location of chronic osteomyelitis was the distal femur and tibia. Anatomical changes in the femur and tibia in all patients had individual differences. Radiological morphological manifestations such as local and general osteoporosis, foci of osteosclerosis, architectonic disorders occurred in all patients. However, the severity of changes in the bone structure was extremely diverse, including the changes in bone density. Conclusion The data obtained indicate that radiological morphological changes in the cortical plate outside the zone of destruction are manifested by formation of microcavities and microabscesses in 15.6 % of patients, what plays an important role in possible recurrence of osteomyelitis.

Introduction It is known that the function and structure of the muscles of the thigh and lower leg are closely related to the function of the lower limb, which is impaired to one degree or another in all patients with chronic osteomyelitis. However, the nature of structural changes in the muscles, which, in turn, affect the condition of the bones, has not been well studied. Purpose of the work To study the features of changes in the muscles of the thigh and lower leg in patients with chronic osteomyelitis according to MSCT data. Material and methods The study is retrospective conducted at a single centre of Evidence level IV. Multislice computed tomography (MSCT) was used in 112 patients with chronic osteomyelitis of long bones of the lower extremities to study the radiological morphology of the muscles of the thigh and lower leg, including density, muscle belly area, and anatomical features. Twenty patients had chronic osteomyelitis in the area of transosseous elements (pins). The mean age of the patients was 48.5 ± 9.8 years. Males prevailed among the patients (87.5 %). The cause of osteomyelitis in 107 cases was trauma or surgery, five patients had consequences of hematogenous osteomyelitis. Results The results of the study showed that the muscles of the thigh and lower leg in patients with chronic osteomyelitis have pronounced dystrophic changes. In 89.4 % of patients, they were manifested by an increase in the density of the anterior tibial muscle, long extensor of the toes (84.7 %), peroneal muscles (78.5 %) and a decrease in the density of the head of the gastrocnemius muscle (91.3 %). In 10.6 % of the patients, there was a decrease in the density of the anterior tibial muscle, the long extensor of the fingers. In all patients with chronic osteomyelitis of the femur, the density of the muscles of the anterior and posterior groups was reduced, except for the musculus vastus intermedius of the thigh that was characterized by fibrotic changes with an increase in density. Conclusion The data obtained indicate that radiological morphological changes in muscles occur in all patients with chronic osteomyelitis of the femur and lower leg. The most pronounced alterations in the architectonics were in the anterior tibial and gastrocnemius muscles, and the intermediate broad muscle of the thigh.

Introduction. In the existing models of osteomyelitis, there is no unified scheme for creating a pathological focus. To obtain reliable comparative data from Introduction There is no unified scheme for creating a pathological site in the existing osteomyelitis models. The location, the size of the defect, the dosage of the infecting agent and the carrier material are to be standardized to facilitate reliable comparative data from different authors and reproducibility of the experimental model. The objective was to demonstrate experimental results of simulated chronic osteomyelitis using a unified scheme for creating a pathological site. Material and methods An identical defect was simulated in the proximal tibia taepiphysis of 15 rabbits using a four-sided cone-shaped drill with a diameter of 0.5 cm and a limiter to a depth of 0.5 cm. An allobone fragment impregnated with Staphylococcus aureus suspension with a microbial cell concentration of 1.0 × 108 CFU/mL was placed into the defect site. A part of sutures was removed from the middle third of the wound and the edges were diluted to initiate a fistula course at 3 postoperative days. An experimental model of chronic osteomyelitis was developed using unified parameters of location, defect size, dosage of the infecting agent and carrier material. The method was technically simple, required no additional infection and provided a chronic osteomyelitic process. Observation period was 21 days. The control of the model formation was produced through clinical observation, inflammatory changes in the peripheral blood, bacteriological, radiological and pathomorphological examinations. Results Postoperatively, the animals demonstrated a decreased physical activity, increased body temperature, impaired function of the operated limb, a non-healing fistula with an abundant purulent discharge of curd consistency formed at the site of the postoperative wound. Computed tomography showed a cavity with irregular sclerotic edges filled with multiple bone sequesters, edema of adjacent soft tissues and fistula at 21 postoperative days. Leukocytosis was observed in the peripheral blood. Bacteriological examination of the wound discharge showed growth of Staphylococcus aureus. Pathomorphological investigation indicated chronic osteomyelitis with bone defects in the proximal metaepiphysis of the tibia and necrotic areas, pronounced leukocyte infiltration, fragments of dissolving bone tissue, growth of connective tissue surrounding foci of chronic purulent inflammation. An experimental model of chronic osteomyelitis was developed using unified location parameters, defect size, dosing of the infecting agent and carrier material. The method was technically simple, required no additional infection and facilitated formation of a chronic osteomyelitic process for 21 days. Discussion We used allobone in our model to cause infection by impregnation of microbial suspension without additional removal of the carrier. The amount of infecting suspension to initiate osteomyelitic process to be absorbed by the allobone and avoid the death of the animal from septic complications was determined in the course of the study. For passive drainage of the wound, a fistula course was provided and its functioning maintained, with the osteomyelitic focus localized and survival of animals ensured throughout the experiment. Conclusions An experimental model of chronic osteomyelitis was demonstrated using a unified scheme for a pathological focus. The model allowed us to avoid generalization of the osteomyelitic process, ensure the survival of animals throughout the experiment and simulate the process being consistent with pathomorphological changes characteristic of human chronic osteomyelitis.

Introduction While the COVID-19 pandemic may still be ongoing, we have simultaneously entered into the post-acute phase of COVID-19, which comes with its own challenges. This case series reports 11 patients of COVID-19 treated with corticosteroids who subsequently developed osteonecrosis of the femoral head (ONFH). Methods All consecutive patients diagnosed on MRI with ONFH from August 2020 to May 2021 and were retrospectively COVID-19 positive were included. The treatment administered for COVID-19 was retrieved and evaluated. The patients were managed for femoral head necrosis, and results were reported. Results Overall, 11 patients developed ONFH in a total of 16 hips. The severity of femoral head necrosis depended on the dose of corticosteroid administered during COVID-19. A high dose for a longer duration resulted in a higher ONFH stage (FICAT & Arlet ). Hips in the lower grade were treated conservatively, and in the higher grade were treated surgically. The follow-up scores of patients demonstrated steady improvement. Conclusions High suspicion of femoral head necrosis has to be considered in patients treated with corticosteroids for COVID-19 as it can aid in early detection and early intervention to preserve the native femoral head.

Introduction Custom-made acetabular componenents demonstrate a higher clinical efficiency in revision hip arthroplasty for 3A and 3B uncontained acetabular defects and pelvic discontinuity in comparison with serial implants. However, the cost of customized implants still outweighs the cost of serial implants. Accordingly, the level of economic feasibility of using different implants for various defects of the acetabulum seems to be interesting to investigate. Purpose To analyze the economic efficiency of using customized acetabular implants for 3A and 3B uncontained acetabular defects and pelvic discontinuity in comparison with serial implants. Materials and methods To assess the economic efficiency, the Markov model was applied. The model was built on the basis of 4-year survival data for aseptic loosening, infection, and dislocation in 133 cases of revision hip arthroplasty. Results According to the results of modeling, over a 5-year cycle, customized implants showed a reduction in costs by 11.7 % and an increase in the quality of life of patients by 0.2 QALY in the group of patients with 3A uncontained defects in comparison with serial implants. In patients with 3B uncontained defects and pelvic discontinuity, custom-made implants also showed a reduction in costs by 20.8 % and 41.1 %, and QALY values were also higher in the groups of patients who had custom-made implants at 0.6 and 1.4 QALY units, respectively. Conclusion The use of custom-made implants is a more cost-effective strategy in comparison with the implantation of serial acetabular components.

Introduction A pathological fracture in patients with primary bone sarcomas is a complication that requires specific management with the prognosis affecting the disease. The treatment strategy of the patients with pathological fracture remains controversial. The aim was to explore the effect of a pathological bone fracture on treatment of pediatric bone sarcoma. Material and methods The study included 141 children with bone sarcomas, residents of Moscow. A pathological fracture was observed in 17 (12.1 %) cases accompanied by osteosarcoma in 10 (58.8 %) cases and Ewing's sarcoma in 7 (41.2 %) cases. Long bones were most common location of the fracture seen in 15 (88.2 %) cases. Results Errors in establishing the diagnosis of bone sarcomas occurred in children with/without a fracture with no statistically significant differences (p = 0.239). There were no statistically significant differences in the volume of surgical interventions, functional assessment using the Musculoskeletal Tumor Society System (MSTS), and 5-year survival in children with/without a fracture (p ≥ 0.05). Discussion Treatment of pathological fractures in children should be produced after obtaining biopsy and the histological diagnosis. The frequency of local recurrence and functional outcome does not depend on the fracture. Conclusion Pathological process is to be ruled out in the presence of a fracture, and adequate visualization using MRI to be followed by a biopsy in a specialized institution would be needed if a pathological focus is suspected.

Introduction Osteoarthritis (OA) has long been considered from the mechanical point of view of etiology and pathogenesis, as a "wear and tear" disease. However, advances in fundamental medicine have changed the way we look at this disease. The role of systemic inflammation was determined in OA progression and risk factor related clinical phenotypes were differentiated as post-traumatic OA, age associated OA, genetic OA and metabolic syndrome associated OA. The development and progression of OA in metabolic disorders envision a concept of systemic regulation of osteocartilaginous and synovial tissues, and several studies showed that dysregulation of circadian rhythms may be involved in the development of dyslipidemia and systemic inflammation associated with obesity. The objective was to explore the effect of melatonin on the dynamics of lipid metabolism and the severity of clinical symptoms in patients with OA and insomnia based on the role of dyslipidemia in the pathogenesis of degenerative diseases. Materials and Methods The study included 36 individuals including 12 healthy volunteers and 24 inpatients of experimental groups with insomnia and Kellgren-Lawrence grades 2 and 3 gonarthrosis. Standard conservative treatment consisted of drug and physical therapy. Medical history, complaints were collected from the patients and physical examination performed to evaluate edema of the joint, alignment of the lower limb, range of motion in the joints and measure waist circumference, body height, body weight; body mass index. The biochemistry blood parameters measured included total cholesterol concentration (TCC), high-density lipoprotein cholesterol, low density lipoprotein cholesterol (LDL) and triglycerides (TG). VAS and Lequesne scale were used to assess pain and function of the joints. Results Patients with the metabolic OA showed statistically significant (p < 0.05) increase in TCC (6.23 (4.28 to 6.44) mmol/L, p < 0.0002), LDL fractions (4.52 (3.08 to 4.92) mmol/L, p < 0.00004), atherogenic coefficient (CA) (4.33 (3.15–4.8) mmol/L, p < 0.00003) and a decrease in the HDL fraction (1.08 (0.93 to 1.4) mmol/L, p < 0.01) before treatment in comparison with healthy individuals. The TG level remained within the normal range (0.73 [0.62 to 0.78] mmol/L). At a month, a statistically significant (p < 0.006) decrease in TC (4.62 [3.71 to 5.29] mmol/L), a decrease in atherogenic fractions of LP (LDL) (2.65 [1.90 to 3.05] mmol / L) (p < 0.002), an increase in the HDL fraction (1.49 [1.17 to 1.72] mmol/L) (p < 0.004) and a decrease in CA (2.07 [1.81 to 2.34] mmol/L) (p < 0.002) were observed in the experimental group of patients who received melatonin at the dose of 3 mg per day as an adjunctive therapy to the basic treatment. There was no significant dynamics of lipid metabolism in patients receiving standard treatment. The Lequesne's functional index significantly (p < 0.03) decreased in melatonin patients after treatment from 12 [12 to 13] to 10 (8.75 to 10.25) points and showed no significant dynamics measuring 10.5 [10 to 11.75] and 10 [10 to 19.25] points in patients receiving standard treatment. Although positive dynamics in VAS scores was observed in both experimental groups a greater improvement (p < 0.005) was seen in the drug group with VAS score improved from 4.5 [3.75 to 5] to 2.5 [2 to 3.25] mm versus 4.5 [4 to 5] and 3.5 [3 to 4] mm in the no-drug group (p < 0.01). Conclusion Melatonin incorporated into the basic therapy was shown to exert a positive effect on pain assessment, condition of the knee joint evaluated with knee rating scales and subjective instruments, objective examination. The moderate antiatherogenic effect facilitates the therapeutic regimen to be considered in management of metabolic osteoarthritis.

Pigmented villonodular synovitis (PVNS) is a rare benign proliferative disorder affecting synovial membranes, bursae, tendons, skin and bone. Materials The article presents a rare clinical case treated for PVNS of the subacromial space. The patient complained of pain in the shoulder joint at the largest possible points, and a deformity developed 7 months prior to the visit could be visualized at the anterior aspect of the shoulder joint. The patient denied any history of trauma. Arthroscopy of the shoulder joint was performed to rule out the intra-articular nature of the lesion with an exploratory puncture performed to establish the diagnosis with instrumental methods. Delto-pectoral approach was used to remove the neoplasm that was histologically examined to confirm the diagnosis. The upper limb was postoperatively immobilized with a Gilchrist-bandage for 2 weeks. The sutures were removed 2 weeks after the operation. Result The patient underwent a course of rehabilitation to restore the function of the upper limb. The upper limb function was preoperatively and postoperatively evaluated with the ASES questionnaire. The patient showed the shoulder function completely regained at two years with ASES scored 100. MRI scan of the shoulder joint showed no signs of recurrence. Extra-articular location of PVNS is very rare and is described in few case reports. Open procedure or arthroscopic removal of the affected synovial membrane are used to treat the condition. Conclusion Removal of the affected synovial membrane allowed us to obtain a good clinical result.

Introduction Malignant tumors are frequently localized in the long bones. Radical resection and reconstruction with megaprostheses is the gold standard of surgery in this group of patients. Unfortunately, the use of standard modular components is not possible in subtotal resection or is associated with a high risk of instability. Development of personalized shortened components of endoprostheses based on 3D computer modeling expands the possibilities of limb salvage surgical treatment. Materials and methods We describe a case of surgical treatment of a patient with extensive tibial fibrosarcoma. Pre-operative diagnosis based on CT, MRI, PET-CT and biopsy was low-grade fibrosarcoma, post-operative diagnosis was the same. Radical subtotal proximal resection of the tibia was performed, and modular knee megaprosthesis based on 3D-modelling custommade distal short tibial component of hybrid fixation was used for reconstruction. Rehabilitation after surgery included wearing knee and ankle orthoses. Results No tumor recurrence or metastases were revealed one year after surgery, functional and radiological results were excellent. Patient walked without support, her gate was correct, and MSTS score was 83 %. Discussion In recent years, custom-made short components of oncological endoprostheses using 3D computer modeling have been developed. The short custom-made tibial component used by us in the report is a combination of a short cemented stem locked with two extraosseous plates with a rough surface. It simultaneously ensures the strength of the implant and increases the contact with the distal tibia. Excellent radiological and functional results obtained one year after the operation allow us to hope for a positive outcome in the medium term and to delay extirpation of the tibia. Conclusion Radical bone resections and megaprosthetic reconstruction in malignant tumors provide the best functional results. Implementation of based on 3D-modelling custom-made prosthetic components in extensive resections is a perspective trend in limb-salvage surgery.

Introduction Gaucher disease belongs to the group of hereditary lysosomal orphan cumulative diseases caused by deficiency of the β-glucocerebrosidase enzyme. It features polysystemic affection, including bone tissue. The osteoarticular system in Gaucher disease is affected in 75–83 % of cases. Moreover, infectious processes may frequently develop, including tuberculosis. Purpose The aim of this work was to demonstrate the features and difficulties in diagnosing osteoarticular pathology in Gaucher disease complicated by tuberculosis infection in patients of different ages. Material and methods The following methods were used in the study: clinical material (including a retrospective case history), additional research methods, imaging diagnosis (radiography, computed tomography, magnetic resonance imaging), data from the protocols of surgical interventions, morphological study of biopsy / surgical material with microbiological confirmation. Results Two case reports are presented that demonstrate destructive changes in bones and joints developed due to Gaucher disease, and its further association with tuberculosis infection. One patient was diagnosed with Gaucher disease in childhood and gradually developed osteoarticular pathology that was later complicated by tuberculous. In the second case, the patient sought medical help due to pain in the lumbar spine as he already had osteoarticular manifestations. Upon further examination at the age of 32, Gaucher disease was diagnosed. Tuberculosis infection of the bones was suspected but was questioned several times by various medical institutions. Conclusion The clinical cases discussed confirm the difficulty of diagnosing osteoarticular pathology in Gaucher disease, especially in associated tuberculosis. This issue dictates the need for a specific examination algorithm.

Introduction Avascular necrosis of the femoral head is a debilitating disease affecting people of working age and having an important medical and social role. Total hip arthroplasty is the only effective treatment for late stages of necrosis. Various joint-preserving operations and non-surgical methods can be successfully used for less severe types. There is no unequivocal opinion on the effectiveness of various conservative treatments offered for avascular necrosis of the femoral head. The aim was to summarize data on the role of medications and physiotherapy in treatment of avascular necrosis of the femoral head through the analysis of the modern world literature. Material and methods The original literature search was conducted on key resources including elibrary, PubMed and ResearchGate. Results Outcomes of avascular necrosis of the femoral head treated conservatively were overviewed. The effectiveness of various treatments using bisphosphonates, anticoagulants, statins, prostacyclin derivatives was evaluated. Physiotherapy with shock wave therapy, pulsating electromagnetic fields, and hyperbaric oxygenation was also reviewed. Conservative treatment is reported to be effective only for early (pre-collapse) stages of avascular necrosis of the femoral head. Conclusions A conservative treatment used as a monotherapy for AVN cannot be assessed as a standalone procedure because various combinations of comprehensive treatment are used for the majority of patients. There are no studies in the literature comparing the effectiveness of conservative therapies using iloprost and statins, bisphosphonates and anticoagulants, shockwave and hyperbaric oxygen therapy in homogeneous patient samples. A deeper study of the underlying pathogenesis of avascular necrosis of the femoral head is required to develop personalized treatment strategies.

Introduction Diabetic neuroosteoarthropathy (DNOAP) is a serious medical and social problem, a potentially life-threatening condition associated with increased mortality. Purpose Analysis of the literature data on DNOAP complicated by osteomyelitis in terms of pathogenesis and histological diagnostic methods. Materials and methods The review considers studies from various information systems (eLibrary.ru, PubMed, etc.) published from 2001 to 2021. Results Differential diagnosis of DNOAP and chronic osteomyelitis is a poorly understood issue. The "gold standard" in determining the nature of bone tissue destruction is bone biopsy. An analysis of the literature shows that changes in the structure of the bone in chronic osteomyelitis are of varying severity, and the determination of its boundaries is of considerable difficulty. Histomorphometric diagnostic criteria for chronic osteomyelitis have not been defined. Studies of pathomorphological changes in foot tissues affected by DNOAP are scarce. The most significant pathomorphological changes in the bone tissue in DNOAP are the following: focal necrosis, desolated osteocytic lacunae, endosteal resorption, thinning of the subchondral layer. The inflammatory infiltrate is mild or moderately expressed and is composed by lymphocytes, plasma cells and macrophages, rarely neutrophils and fibroblasts. One of the leading components in the initiation of pathological changes in the tissues of the foot affected by DNOAP is pronounced disorders in the structure of the vessel wall. Degeneration processes are expressed in peripheral nerves. Conclusion The pathogenesis of the Charcot foot and pathomorphological changes in the tissues of the foot, depending on etiopathogenetic factors and comorbidity, is not well understood. Histological studies of foot tissues in this pathology are promising for the differential and early diagnosis of Charcot foot, justifying the need for an individual approach to treatment, paying attention to certain morphological changes.

Inflammation plays critical role in the onset and progression of osteoarthritis (OA), a joint disease affecting more than 10 % of the world's population. Exporing immunological mechanisms of osteoarthritis is essential. The present paper is a literature review of immunogenetic aspects of the pathogenesis of the disease. The study is aimed at analysis and summary of information concerning the immunogenetics and molecular mechanisms of osteoarthritis. Material and methods The original literature search was conducted on key resources including Scientific Electronic Library (www.elibrary.ru) and the National Library of Medicine (www.pubmed.org) with subsequent selection of articles, analysis and synthesis of information. Results and discussion Mutations in proinflammatory cytokine and receptor genes, metalloprotease genes, HLA genes and in the anti-inflammatory cytokine (IL-4) gene, polymorphisms in phospholipase and IL-2 genes are more common for OA patients than for healthy subjects. Epigenetic regulation in OA include a decreased methylation of the promoters of proinflammatory cytokine and metalloprotease genes and a decreased methylation of NF‑κB‑sensitive iNOS enhancer sites. OA patients show an increased activity of histone acetylases in the IL-6 promoter area. In contrast, the expression of anti-inflammatory cytokines is decreased due to the reduced activity of the SIRT1 deacetylase.

Introduction Neurofibromatosis type 1 (NF1) is one of the most common hereditary tumor syndromes. The average incidence of NF1 in the world is 1:3000 of the population. The characteristic signs of the disease are neurofibromas and café-au-lait macules on the skin. 60 % of patients with NF1 develop specific skeletal anomalies: scoliosis, chest deformity, pseudarthrosis, requiring surgical treatment and long-term rehabilitation. It is necessary to develop prognostic criteria for the development of severe skeletal anomalies in NF1 and take early measures to prevent their progression. Congenital pseudarthrosis of the tibia is diagnosed in 5 % of children with NF1, accounting for 80 % of all cases of this pathology in the general population. Spinal scoliosis is detected in 60 %, osteoporosis in 50 %, chest deformity in 37.6 %, microgenia in 53 %, increased head circumference in 25 %, sphenoid wing dysplasia in 12 %, facial asymmetry in 10 % of patients with NF1. The aim of the review is to focus on the pathogenesis of skeletal anomalies development in NF1 that result in disorders of the musculoskeletal system in NF1 in order to take early measures for the prevention and treatment of the disease. Materials and method The review is based on numerous studies found in the databases: PubMed, Scopus, Web of Science, published mainly over the past 5 years. The suitable studies were searched by keywords and their combinations «neurofibromatosis type 1» with the words «skeletal abnormalities», «musculoskeletal system», «pseudarthrosis», «scoliosis», «pathogenesis», «deformation», «treatment», «frequency», «prevalence», «genotype-phenotype correlation», « modifier genes». Results and discussion The pathogenesis of skeletal anomalies is due to both the loss of heterozygosity of the NF1 gene in pseudoarthrosis and the effect of neurofibromin deficiency on the development of connective tissue. Currently, the only effective drugs for the treatment of tumor syndrome in NF1 are inhibitors of mitogen-activated kinase (MEK), which suppress the increased activity of Ras oncogenes. A promising issue is the study of the effect of MEK inhibitors on the progression of skeletal anomalies in patients with NF1 in the treatment of tumor syndrome. Therefore, dynamic observation by an orthopedic surgeon with an objective assessment of the observed changes is of great importance in the management of patients. It is necessary to widely introduce molecular genetics methods for confirming the diagnosis of NF1 in the clinic in cases of a combination of skeletal anomalies with individual signs of the disease, since the manifestations of NF1 are steadily progressing with age, even in the presence of erased and atypical forms of the disease. Since the analysis of scientific literature has shown the possible influence of modifier genes on the pathogenesis of NF1, the search for mutations in these genes is promising. Conclusion Most patients with NF1 develop orthopedic pathology, which is associated with the role of the NF1 gene in the development of connective tissue. The increased mutability of this gene causes the loss of heterozygosity in the development of congenital pseudoarthrosis of the tibia. At the same time, NF1 driver mutations are detected in 10 % of sporadic malignant neoplasms. Therefore, the role of somatic mutations in the NF1 gene in the development of skeletal anomalies in the general population is probable. The methods of NF1 therapy that are under investigation may become the basis for the complex treatment of oncological and orthopedic patients.