BACKGROUND: Endoprosthesis after bone and joint resection is the treatment of choice for patients with malignant bone tumors, especially in case of a favorable oncological prognosis. Endoprosthesis bone site infection and relapse associated with the underlying disease are important complications that are difficult to treat. The development of periprosthetic infection leads to the loss of functional potential after the end of this complication treatment and worsens oncologic prognosis. AIM: To study and improve the long-term results of treatment in patients with diagnosed periprosthetic infection who underwent oncologic endoprosthesis, to develop a preventive complex of measures aimed at reducing periprosthetic infection. MATERIAL AND METHODS: The study included 1292 patients with primary bone sarcomas, soft tissue sarcomas, metastatic and benign bone tumors who underwent 1671 primary and recurrent endoprosthetic replacements between January 1992 and January 2020. A total of 677 (52.4%) men and 615 (47.6%) women participated in the study. Patients ranged in age from 10 years to 81 years. Oncologic endoprosthetics were performed in 886 (68.6%) patients with primary malignancies, 144 (11.1%) with metastatic bone lesions, and 262 (20.3%) with benign neoplasms. The mean follow-up period after endoprosthetic replacement with various bone segments was 82.8 months (0-335.7 months). RESULTS: The incidence of periprosthetic infection during the entire follow-up period in primary endoprosthesis was 7.1%, and in repeat endoprosthesis 6.2%. The recurrence rate of endoprosthesis infection in primary endoprosthesis during the observation period was 83%, in repeat endoprosthesis 61.5%. The frequency of periprosthetic infection was reduced by changes in the endoprosthetic strategy. The prevalence of early (type IVA according to ISOLS 2013) infectious complications (15 and 11.9%) over late (type IVB) complications (5 and 4.4%, respectively) in both primary and repeat arthroplasty was higher. Staphylococcus aureus was most frequently identified after primary endoprosthetic replacement (38.1%) and Staphylococcus epidermidis was most commonly verified after repeat endoprosthetic replacement (53%). Two-stage reendoprosthesis was used most often to treat periprosthetic infection: after primary endoprosthesis in 58.3% of cases, after repeat endoprosthesis in 65.4%. The preventive measures developed in the study made it possible to reduce the incidence of the endoprosthesis site early infection by 15.3% in primary endoprosthesis and by 7.1% in repeat endoprosthesis. CONCLUSION: The perioperative antibiotic prevention regimen should provide a steady antibiotic concentration during the entire course of surgery and the time associated with the highest risk of endoprosthesis site early infection (extended antibiotic treatment up to 5 days), which allows to reduce the wound microbial contamination to a safe level. The findings suggest that two-stage reendoprosthetic replacement remains the main treatment option for periprosthetic infection.

Introduction. The distal tibia and fibula are rare sites of involvement by primary and metastatic tumors. For a long time, amputation remained the standard surgical intervention for this location. Oncological ankle replacement is associated with a number of difficulties, including a lack of soft tissue necessary to cover the implant, close proximity of anatomical structures, a high probability of vascular and infectious complications, and difficulties in restoring the biomechanics of the lost joint. Currently, due to the small number of analyzed groups and short-term observations, there is no generalized data on primary and revision oncological ankle replacement, and there is no developed approach to treatment and prevention of complications.Aim. To generalize the analysis of long-term results, the structure of complications, and functional results in a group of patients after primary and revision oncological ankle replacement in a statistically significant group of patients.Materials and methods. The study included 40 patients with benign bone tumors, primary localized sarcomas of bone and soft tissue, and metastatic lesions, which, since 2008, until 2023 56 primary and revision endoprosthetics of postresection defect of the distal tibia were performed. Over a period of 15 years, the study group included 40 (71.4 %) surgeries in the scope of primary endoprosthetics and 16 (28.6 %) surgeries in the scope of revision oncological endoprosthetics of the ankle joint.Results. Over a 15-year follow-up period, the overall incidence of complications, structured according to the International Society of limb Salvage (ISOLS) 2013 classification, after primary and revision arthroplasty was 50 %. The average time until detection of oncological and non-oncological complications was 16.1 months. The leading complication after endoprosthetics was aseptic instability (Type II; 21.4 %) and tumor recurrence (Type V) – 20 %. The average functional outcome after primary and revision ankle replacement was assessed using the MSTS scale and was 72 % after 6 months and ranged from 43 to 97 %. After 12 months, this figure was 78 % and ranged from 49 to 97 %.Conclusion. An objective assessment and increase in the statistical reliability of the results of oncological ankle replacement requires a larger number of surgeries, a longer observation period and joint consolidation of data from various clinics. Development of indications for such reconstructive operations, careful selection of patients taking into account the effect of conservative treatment allows to reduce the total number of complications, the number of local relapses and achieve a good functional result.

Introduction . Giant cell tumor of bone is a relatively rare, locally aggressive osteolytic skeletal neoplasm with uncertain behavior: recurrence rates up to 70 % and distant metastases occur 2–6 % of cases. Nowadays denosumab is the choice of therapy for patients with unresectable or advanced disease. However, the efficiency, duration or administration and most of all safety of continuous denosumab are not established. Materials and methods . Fourty advanced or unresectable giant cell tumor cases were observed from 2005 till 2020 in N.N. Blokhin National Medical Research Center of Oncology. The average age of pts was 33,6 ± 13,1 years (18–64), and the women and men ratio was about 2,1 : 1. The most commonly affected sites were long bones of the lower extremities (22,5 %), sacrum (22,5 %), long bones of the upper extremities (17,5 %), spine (17,5 %), pelvis (10 %) and others. 70 % of cases were anatomically compounded due to tumor localization and 27,5 % of cases were primary disease. 37,5 % of cases were with pulmonary metastases. Patients underwent computed tomography / magnetic resonance imaging every 3 months during the first three years and then once every six months. Patient received subcutaneous denosumab 120 mg every 4 weeks with a loading dose of 120 mg subcutaneous on study days 8 and 15. After 2 years monthly therapy and confirmed stabilization effect patient then received maintenance therapy: once in three months injection. All patients received daily calcium and vitamin D supplement. Results . Median follow-up was 52,8 ± 41,3 months (3–219 months). The average denosumab injections were 25 ± 16 (4–85). Clinical and radiographically stabilization of the effect occurred on average at 12 ± 8 (4–32) injections. Hypocalcemia was registered in one case (2.5 %). There was significant improvement of Karnofsky scale, Visual analogue scale (VAS) and Watkins scale (p <0.001). 5-year progression-free survival for was 70.1 % (95 % confidence interval 55.7–88.0), the median was not reached. Progression of disease was observed only in subgroup with violations in denosumab administration or its cancellation (32,5 %). 3-year progression-free survival in subgroup with violations in denosumab administration or its cancellation was 10 % (95 % confidence interval 15.5–64.1). In subgroup with continuous denosumab and once in three months injection after 2 years monthly therapy there was no signs of progression. Conclusions . In this study we showed evidence of safety and effectiveness of continuous denosumab for unresectable or advanced giant cell tumor even with once in three months injection therapy. Denosumab for advanced giant cell tumor of bone became a choice of treatment, but we need further investigation for observation long term denosumab effectiveness and complications.

Introduction . Primary malignant tumors of the skeletal system mostly develop in young and middle-aged people. Morbidity in this age group amounts to between 75 and 80 % of overall morbidity. Due to low survival caused by patient death in the first 5 years mostly because of metastases of primary malignant tumors, the main focus of treatment was on prolongation of life, study and development of new methods of conservative therapy. Therefore, until the early 1970 amputation surgery was the generally accepted standard of surgical intervention. Positive oncological results required revision of the surgical concept of treatment in this patient group. This problem was solved through active development of oncological endoprosthesis started in the second half of the 1970s and led to shaping of orthopedic oncology into a separate oncological specialty. The study objective is to study long-term oncological results of treatment of patients with primary and metastatic tumors of the locomotor system after oncological endoprosthesis. Materials and methods . The study included 1292 patients with primary sarcomas of the bones, soft tissues and patients with metastatic and benign bone tumors who underwent 1200 bone resections/extirpations of varying scale with endoprosthetic replacement between January of 1992 and January of 2020. In the total group of patients who underwent endoprosthesis, the number of men and women was approximately the same: 677 (52.4 %) and 615 (47.6 %), respectively. At the time of surgery, age of the patients in the total group varied between 10 and 81 years. Mean patient age was 34.7 years. Most commonly, endoprosthetic replacement was performed in patients between the ages of 21 and 30 years (in 29 % of cases). Oncological endoprosthesic replacement was performed in 814 (67.8 %) patients with primary malignant tumors, 143 (11.9 %) patients with metastatic lesions in long bones, and 243 (20.3 %) patients with benign neoplasms. Mean follow-up period after endoprosthesis of different bone segments was 82.8 months (between 0 and 335.7 months). Results . In 27 years of observations, total frequency of recurrences after endoprosthesis for various tumor locations (type V complication per the International Society of Limb Salvage system (2013) (ISOLS 2013)) was 8.8 % (86/979); among them recurrence in the bone (type VA complication) was observed in 1.7 % (17/979) of cases, recurrence in the soft tissues (type VB complication) in 7.0 % (69/979) of cases. Primary endoprosthetic replacement due to recurrence after previous surgical treatment leads to 2.2-time increase in the risk of development of this complication. The obtained results show that repeat recurrence significantly increases the risk of recurrence in soft tissues and does not affect the risk of recurrence in the bone. The most recurrences developed in patients with non-differentiated pleomorphic sarcoma (15.4 % of cases), chondrosarcoma (15.0 % of cases) and parosteal osteosarcoma (14.3 % of cases). Frequency of recurrences in patients with giant cell bone tumors and aneurysmal bone cysts was 4.0 and 3.8 %, respectively. In cases of tumor recurrence after endoprosthesis, limb amputation was the most common treatment: 33.7 % (28/83) of cases. In this study, recurrence mostly developed after femur resection with knee joint endoprosthesis: in 45.8 % (38/83) of cases. Frequency of oncological complications in patients with bone sarcomas who underwent endoprosthetic replacement was 31.9 % (283/886). In the total patient group in 27 years of observations, in 25.3 % (224/886) of patients disease progression in the form of metastases was observed. Local tumor recurrence was accompanied by metastases in 6.7 % (59/886) of cases. Conclusion . Decreased risk of development of local recurrences depends on the effectiveness of complex approach to therapy in this disease group. Changes in surgical endoprosthesis techniques in tumors of varying differentiation levels allowed to achieve significant radicalness of treatment. Progression risk for bone sarcomas, level of response to specialized therapy and, as a result, patient’s prognosis depend on the presence of epigenetic, genetic, molecular and chromosomal abnormalities.

Introduction.The results of using various reconstructive technologies in the 1980–1990’s to replace post-resection bone defects determined oncological endoprosthetics as the most promising onco-orthopedics trend, due to the quality-of-life and functional potential restoration in a short time. Despite the constant improvement of the design and technology of oncological endoprosthesis at the moment, complications such as aseptic instability, mechanical failure and infection of the endoprosthesis significantly affect the reduction of implant survival. It is impossible to reduce the frequency of endoprosthesis aseptic instability without developing a unified strategy for the prevention and treatment of this type of complication.The study objective – to examine the main causes of early and late aseptic loosening, analyze complication rate in various periods after endoprosthesis using literature data and results of treatment of a large patient group who underwent primary and repeat endoprosthesis for different post-resection bone defects.Materials and methods. The study included 1292 patients aged 10 to 81 years with primary bone and soft tissues sarcomas, metastatic, benign lesions of the bone, who since January 1992 to January 2020 were performed 1671 primary and revision endoprosthetics of various bone segments. The age of the patients ranged from 10 years to 81 years. The mean age of the patients was 34.7 years. In the study group of patients, most often endoprosthetics was performed at the age of 21 to 30 years and accounted for 29 % of cases. The mean follow-up period after primary arthroplasty of various segments was 82.8 months (from 0 to 335.7 months). The mean follow-up period after revision arthroplasty was 54.2 months (from 0 to 282.8 months). In 1594 (95.4 %) cases were used bone cement stem fixation.Results. The results of the study show that the optimal shape of the endoprosthesis stem for primary and revision endo-prosthesis replacement is conical and cylindrical figured (made in the shape of the bone marrow canal). The most stable endoprosthesis stems are 60–100 mm long for upper limb arthroplasty and 110–150 mm for lower limb arthroplasty. Endoprosthesis stems longer than 160 mm can only be used in revision endoprosthetics. The length of the bone resection does not affect the incidence of endoprosthesis instability. The quality of the formed cement mantle affects the frequency of endoprosthesis instability. The presence of at least one revision arthroplasty with replacement of the endoprosthesis stem increases the risk of developing subsequent early instability (type IIA) about 4 times and the risk of late instability (type IIB) about 6 times compared with primary arthroplasty. The occurrence of late aseptic instability of the endoprosthesis (type IIB) will lead to the development of breakage/destruction of the endoprosthesis (type IIIA) in a shorter period than the breakage/ destruction of the endoprosthesis will lead to the development of late instability of the endoprosthesis (type IIB).Conclusion. The choice of an endoprosthesis, taking into account the optimal biomechanics of the endoprosthesis design, the shape of the stem, methods of fixation, the introduction of innovative technological solutions, adherence to the principles of oncological endoprosthesis replacement, is a means of reducing the incidence of this type of complications.

In the surgical treatment of benign as well as low aggressive malignant (G1) bone tumors of small sizes, methods such as intralesional curettage, marginal resection, resection of part of the joint, or resection of the affected bone segment are used. In cases when intraosseous removal of the tumor is performed, there is a need for bone grafting of the defect, the purpose of which is to maintain and strengthen the structural strength of the bone, replace the volume of the bone defect, and accelerate the biological stimulation of bone tissue regeneration during fractures. The most widespread use of synthetic bone graft substitute based on calcium sulfate and calcium phosphate. The study included 24 patients, 15 (62.5%) of whom were diagnosed with chondrosarcoma G1, 9 (37.5%) were diagnosed with enchondroma. For these patients, from 2015 to 2019 (52 months), surgical treatment was performed in the amount of curettage with replacement of the defect with the phosphate calcium bone graft substitute. In the studied group of patients, in 12 (50%) the tumor was localized in the femur, in 10 (41.7%) in the humerus, in the tibia and radius of the 1 patient, respectively. The mean follow-up period was 32 months and ranged from 7 to 52 months. In the present study, during the observation period, none of the patients was diagnosed with local recurrence, distant metastasis, bone fracture, loss of bone graft substitute and infection. All patients showed satisfactory integration of tricalcium phosphate bone graft substitute. The average functional result after 6 months for the upper limb was 94%, for the lower limb 96%, according to the MSTS scale. Replacing of the formed bone defects with a synthetic bone graft substitute containing tricalcium phosphate provides reliable, predictably fast kinetics of resorption and substitution.

Background. The standard treatment for giant-cell tumors of the bone includes radical surgery. However, specific anatomical location of the tumor and/or its spread may hinder its complete excision or result in poor functional outcomes. Currently, combination treatment that includes preoperative denosumab and surgery is preferable. It saves patients’ lives and improves their quality of life. Reduction of local recurrence rate by combination therapy for giant-cell tumors of the bone is being actively studied now.Objective – to analyze treatment outcomes of patients with giant-cell tumors of the bone, including those who received combination treatment that included preoperative therapy with denosumab followed by surgery.Materials and methods. This study included 277 patients with giant-cell tumors treated in N.N. Blokhin National Cancer Research Center between 2005 and 2020. The mean duration of follow-up was 56 months. Study participants were divided into two groups. Group 1 included patients who received surgical treatment alone (n = 212), whereas Group 2 comprised patients who received combination treatment (n = 65). Neoadjuvant therapy included subcutaneous denosumab 120 mg on days 1, 8, 15, and 28, then every 4 weeks until stable effect. There were two variants of surgical treatment: radical (removal by a single block or segmental resection with defect replacement, with or without fixation) and non-radical (excochleation or marginal resection with defect replacement, with or without fixation).Results. During treatment, patients in Group 2 had a significantly milder pain syndrome (assessed both using the visual analog scale for pain and Watkins scale) compared to Group 1. In case of radical surgery, the incidence of local recurrence was 12 % and 0 % in Groups 1 and 2, respectively; the difference was significant (р <0.05). Tumor location and volume of surgery played an important role in disease recurrence (р <0.05). The incidence of complications after radical surgery was 36.9 % and 12.5 % in Groups 1 and 2, respectively; the difference was significant (р <0.05). In addition to that, neoadjuvant therapy with denosumab substantially reduced the duration of surgery and blood loss in patients with challenging anatomical location of the tumor (р <0.05).Conclusion. Combination treatment for giant-cell tumors that includes neoadjuvant therapy with denosumab reduces the risk of recurrence, duration of surgery, blood loss, and the risk of postoperative complications. However, it is important to consider tumor location and the volume of surgery. Since the disease is quite rare, further study of long-term efficacy and safety of combination treatment for giant-cell tumors, including rare ones and those with challenging anatomical location, is necessary.

Introdaction. In the general structure of oncological endoprosthetics, primary lesions of the distal tibia are rarely affected. Endoprosthetics of the ankle joint region are associated with characteristic difficulties consisting in soft tissue deficiency and restoration of the biomechanics of the lost joint. The existing scientific volume of the literature data on primary ankle replacement is insignificant. At the moment, there is no experience and clear strategy in revision endoprosthetics of this area, complications remain insufficiently explored.Objective. The aim of the study was a discrete analysis of medium- and long-term results, the structure of complications, and functional results in a group of patients after primary and repeated oncological ankle replacement.Materials and methods. The study included 20 patients with benign and malignant bone tumors, who from July 2008 to November 2019 underwent 33 primary and revision replacements in case of distal tibia tumor lesion. In the study group of patients, 70 % were diagnosed with a primary malignant tumor and 30 % had a benign lesion of the tibia. The mean follow-up period was 58,6 months.Results. The leading complication after primary and revision endoprosthetics was early aseptic instability (type IIA) – 20,0 and 23,1 %, respectively. Primary and revision endoprosthetics survival after 5 years was 40,1 ± 12 %.Conclusion. The average functional result after primary and revision ankle replacement was evaluated according to the MSTS scale and after 6 months was 70,5 % and varied from 40 to 87 %. After 12 months, this figure was 76 % and ranged from 46,7 to 96,7 %.The choice of an endoprosthesis, taking into account the optimal biomechanics design of the endoprosthesis unit, methods of fixation, the introduction of innovative technological solutions in the design, materials of the endoprosthesis, adherence to the principle of radicalism will become a means of reducing the frequency of complications.

AbstractA methodology has been developed for measuring radius R _v and eccentricity (conic parameter k ) of large concave aspherical mirrors using a wavefront sensor. Analytical expressions that directly relate Zernike coefficients a _4 and a _9 to parameters R _v and k of the mirror are obtained. It is shown that the technique does not require accurate mirror alignment before measurements. A computer analysis showed that the developed scheme enables measurements with errors of δ R _v < 0.1% and δ k < 0.01 for mirrors with radii from 100 to 2000 mm and with errors of δ R _v < 0.01% and δ k < 0.001 for mirrors with radii of more than 5000 mm.

A methodology has been developed for measuring radius Rv and eccentricity (conic parameter k) of large concave aspherical mirrors using a wavefront sensor. Analytical expressions that directly relate Zernike coefficients a4 and a9 to parameters Rv and k of the mirror are obtained. It is shown that the technique does not require accurate mirror alignment before measurements. A computer analysis showed that the developed scheme enables measurements with errors of δRv < 0.1% and δk < 0.01 for mirrors with radii from 100 to 2000 mm and with errors of δRv < 0.01% and δk < 0.001 for mirrors with radii of more than 5000 mm.

В эпоху применения различных металлических и других устройств с лечебной целью отмечается появление инфекций, связанных с установкой и длительным нахождением этих устройств (англ. – device) в организме человека. Помимо широкораспространенных катетер-ассоциированных инфекций (КАИ) кровотока и КАИ мочевых путей, а также инфекционных эндокардитов, связанных с протезированием клапанов, все большее значение приобретают перипротезные инфекции (в ортопедии, онкоортопедии), инфекции, связанные с установкой сеток (в хирургии), стентов (в сосудистой хирургии и др.), водителей ритма (в кардиохирургии) и др. В основе подобных инфекций лежит формирование биопленок, которые затрудняют микробиологическую диагностику инфекции и ее лечение в связи с антибиотикорезистентностью микроорганизмов в биопленке. Подробно представлены данные по инфекциям в ложе эндопротеза, их этиологии, подходам к диагностике и лечению.

The current statistical data show an increased number of malignancies with skeletal bones involvement, that comprise in average 1.5-2 % of all malignancies. Among them according to some authors, the most common, in decreasing order of incidence, are: multiple myeloma (35-50 %), osteosarcomas (20-30 %), chondrosarcomas (10-17 %), Ewing’s sarcoma (6-12 %), and lymphomas (3-7 %). Therefore, the issue of treating pathological fractures of the spine in multiple myeloma or lymphoma becomes more pressing, since the number of such patients is increasing. Existing surgical minimally invasive techniques enable to increase the quality of life in these groups and start special conservative treatment as soon as possible.

Data on the retrospective analysis of 245 cases of endoprosthetic replacement of bones and major joints are presented. Intraprosthetic infection-related complications were reported in 11%. They developed within 3 months in 64% and their frequency was significantly higher in cases of repeat surgery, resection of proximal tibia with subsequent endoprosthetic replacement of defective knee joint as well as adjuvant polychemotherapy. Anti-infective treatment alone was effective in 11%; complications were aborted by means of surgery of varying extent in 75%.

Most patients had bone malignancies 223 (86,7%) and 34 (13,2%) patients had benign bone lesions. Knee implants were made in 181 (70,4%), shoulder implants in 24 (9,3%), hip joint implants in 38 (14,8%), elbow implants in 4 (1,6%) cases. Total replacement of the upper arm was made in 1 (0,4%), total replacement of the thigh bone in 8 (3,1%) and replacement of the femoral diaphysis in 1 (0,4%) cases. Postoperative events included surgical complications (16, 6.2%), purulent inflammations 32 (12,5%), orthopedic complications 17 (6,6%). Local recurrence was detected in 25 (9,8%) cases.