The article presents the results of endoprosthesis replacement of joints and bones in 19 patients with bone metastasis. The complications resulted from endoprosthesis replacement of joints and bones in cases of bone metastasis were observed in 4 (21.1 %) patients, and tumor recurrences were observed in 2 (10.5 %) patients. In the preoperative period, 19 patients underwent courses of external beam radiotherapy with a total radiation dose (TRD) of 40 Gray, with a single mediated dose (SMD) of 2–2.5 Gray. Also, all patients received preoperative multiagent chemotherapy treatment cycles depending on the primary source of the tumor, and in cases of hormone-dependent tumors, the patients received hormone therapy. Depending on the specific anatomical and functional changes, special implant designs, tools, and techniques were used, which complemented the standard technique of operations. The basic principles of oncosurgery have been adhered to during endoprosthesis replacement of joints and bones, i.e. standard principles of resection and ablastics, removing en bloc of a biopsy area. In endoprosthesis replacement, a cement type of endoprosthesis fixation was used. For an adequate formation of the muscle envelope of the endoprosthesis, a plastic stage of the ope-ration was performed, which allowed to adequately cover the installed endoprosthesis, and thus, reduce the risk of infectious complications. Both displaced and free vascularized musculocutaneous flaps on microvascular anastomoses were used as plastic material. To limit the contact of the metal part of the endoprosthesis with the surrounding tissues and to reconstruct the tendon ligamentous apparatus, a tube of polyethylene tetraphthalate was used, resected tendon and muscles were sutured to it, which allowed to more fully restore joint action. The functioning of extremity according to the MSTS scale after endoprosthesis replacement of joints ranged from 70 to 92 %, and also the quality of life of patients improved up to 70–75 points.

The article contains analysis of complications after individual oncological knee joint endoprosthesis replacement in cases of tumor lesions. Complications were observed in 45 ,8% of cases after knee joint endoprosthesis replacement operations with tumor lesions. The main complications that were observed included infectious ones: 18,1%, aseptic instability of the endoprosthesis stem:  16,7%, bone fracture at the site of endoprosthesis stem implantation: 6,9%, destruction of the endoprosthesis structure: 4,2%. The factors that led to complications, as well as methods of their elimination are given. Dialysis and a long course of antibiotic therapy or the installation of a metal-cement spacer device followed by repeated endoprosthesis replacement is advised in case of an infectious complication. Repeated joint endoprosthesis replacement with replacement of only one (loose) component of the endoprosthesis, using a long intramedullary stem or replacement of the total endoprosthesis is advised in case of aseptic instability of the endoprosthesis stem. Metallic osteosynthesis of the  periprosthetic bone fracture is performed using bone plates  and cable grip in cases of bone fracture at the site of endoprosthesis stem implantation. Repeated joint endoprosthesis replacement is effected with replacement of the entire endoprosthesis structure in case of destruction of the endoprosthesis structure.

We discuss analysis of function outcome and complications in 65 patients undergoing endoprosthetic knee replacement for osteosarcoma after radiotherapy and multiagent chemotherapy. Specifically, we found that multiagent chemotherapy caused a periprosthetic infection in 7.7% of cases. Major complications of radiotherapy included periprosthetic infection (27.3%), bone fracture at the site of endoprosthesis stem implantation (27.3%), aseptic loosening of stem (18.2%) and in 9.1% of patients a post-radiation skin ulcer was observed. Strategies for eliminating complications of periprosthetic infection included: removal of the endoprosthesis, installation of a metal-cement spacer followed by repeated joint endoprosthesis replacement. Then metal osteosynthesis was performed with cover plates and cable grip in case of bone fractures at the site of endoprosthesis stem implantation. A revision knee replacement surgery was performed in case of aseptic loosening of stem; removal of ulcer, removal of necrotic tissue, wound revision, and wound closure by means of muscle reposition with the subsequent free skin grafting was carried out during removal of postradiation ulcer. Hip amputation or disarticulation of the thigh was carried out in case of recurrence; multiagent chemotherapy with metastasioctomy was performed in case of metastases in lung.