Long-term results and modern principles of prevention and treatment patients with endoprosthesis aseptic instability in oncology

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.