Аннотация:Introduction/Purpose: Cardinal positive changes in oncological results of treatment, actualized the need to improve the quality of life in group of patients with tumor lesion located in rare anatomical localizations and move from amputational surgery to organ-preserving. The purpose of this study was to analyze long-term oncological and orthopedic outcomes, the incidence of complications depending on the anatomical area of endoprosthetics in patients with primary tumor and metastatic lesions of long tubular bones over a period of 22 years.Material/methods: Since 1995 to 2017, 138 primary and revision endoprosthetics were performed in rare anatomical localizations. Primary/revision endoprosthetics was performed in the following rare anatomical regions: 1) diaphysis of the humerus 8/3; 2) total endoprosthesis of the humerus 8/2; 3) elbow joint 15/4; 4) wrist joint 1/0; 5) femoral diaphysis 10/3; 6) total femoral arthroplasty 66/25; 7) diaphysis preserving the total hip replacement of the femur 1/0; 8) total endoprosthesis of the tibia 4/1; 9) ankle joint 25/8. The study included 79 men and 59 women. The age of the patients ranged from 16 to 69 years, the average age was 35.8 years. In the morbidity structure, 106(76.8%) were diagnosed with a primary malignant tumor (chondrosarcoma, osteosarcoma, Ewing's sarcoma, undifferentiated pleomorphic sarcoma, periosteal, parostal sarcoma, angiosarcoma, reticulosarcoma), 14(10.1%) with metastatic damage, 18 patients (13%) had a benign diagnosis.Results: In group of 138 patients, the total number of orthopedic and oncological complications was 29.7%. Complications associated with soft tissue failures arose in 3%. Aseptic instability in 8%. Structural failures in 5.8%. Bone fracture 0.7%. Endoprosthesis infection 5.8%. Tumor recurrence in 6.5%. The total number of complications: 1) ankle joint 52%; 2) diaphysis of humerus 50%; 3) total femoral endoprosthetics 27.2%; 4) total endoprosthesis of the tibia 25%; 5) femoral diaphysis 20%; 6) elbow joint 13.3%; 7) total shoulder arthroplasty 12.5%. The average period before non-oncological complications was 22.8 months. The average time to oncological complications was 25 months. The average time to relapse was 22 months. The average time to metastasis was 28 months. The prevalent number of complications of rare anatomical localizations occurs with endoprosthetics of the ankle and diaphysis of the humerus.Conclusion: Reconstructive primary and revision arthroplasty of rare anatomical areas have a significant potential, the development of which requires the joint work of surgeons and engineers. The production of endoprostheses that most fully imitates physiology and biomechanics of the human joint, the completion of the surgical technique of endoprosthetics will reduce the number of complications, increase the qualitative operational capabilities of the endoprosthesis, and reduce the frequency of revisions. Endoprosthetics of rare anatomical areas in some cases is an alternative type of endoprosthetics allowing qualitatively improve the functional capabilities, reduce the volume of endoprostheses and the traumatism of ongoing surgical treatment. Careful selection of patients, taking into account the effect on conservative treatment, allows to reduce the number of local relapses, achieve a good functional result. Performing more operations of rare anatomical areas will allow more objective and reliable evaluation of the results.