ИСТИНА

Introduction/Purpose: Cardinal positive changes in oncological results occurred in the treatment of bone tumor lesions actualized the need to improve the term of megaprosthesis use. The sensitizing capacity of acrylates, as the additives used for the polymerization of the bone cement and optional antibiotic supplements, is another problem which among others leads to stem aseptic loosening. The use of a cementless stem endoprosthesis reduces the risk of aseptic instability in the medium and long term. The purpose of this study was to analyze the possibility, orthopedic outcomes, complication risks and incidence of using cementless stem after the previous cemented arthroplasty based on the introduction of modern technological developments. Material/methods: Since 2014 to 2019, 10 revision endoprosthetics were performed with the application of technology cemented to cementless stem replacement. There were 4 males and 6 females with a mean age of 31,7 years (range, 22-39). In the morbidity structure, 50% were diagnosed with a primary malignant tumor (chondrosarcoma, osteosarcoma) and 50% had a GCT diagnosis. Аll patients at the time of surgery had no signs of disease. Nine replacement was performed after primary distal femur resection and one after previous revision replacement. Complete replacement of cemented to cementless endoprosthesis was performed in 7 patients and partial replacement (one stem) was performed in 3 patients with hybrid endoprosthesis, the model and design was preserved. Five patients had acrylate allergy. Results: The mean follow-up time after prosthesis exchange surgery was 24,6 months (min 9 months, max 56 months). During this period in group of 10 patients there were no orthopedic and oncological complications and signs of allergy. The radiological evaluation during the observation period showed satisfactory osseointegration of the cementless tibial and femoral sterms, which remained firmly attached, with no evidence of loosening or vertical migration. Bone cement mantle was completely purged by ultrasonic cement removal under endoscopic control which allowed obtaining satisfactory fixation. Osteolytic destruction defects of the bone marrow channel in 3 patients which pre-dates aseptic loosening were filled with tricalcium phosphate+ hydroxyapatite allograft. In all patients this technology showed satisfactory osseointegration and and extra stability of cementless stem. Functional result estimated by MSTS scale before surgery was 67,4%, six month after 95,3%, 12 month after 96,1%. Conclusion: Technology of replacing the cemented stem of the endoprosthesis to cementless have a significant potential, the development of which requires the joint work of surgeons and engineers. The use of this technology allows minimizing the risk of aseptic loosening and especially in patients with an allergic reaction to acrylates. Careful adherence to patient selection criteria avoids the complications of its use.