Mechanical Damage of Knee Endoprosthesis in Children with Malignant Bone Tumors. 49th CONGRESS OFT HE INTERNATIONAL SOCIETY OF PAEDIATRIC ONCOLOGY (SIOP) WASHINGTON, DC,USA,OCTOBER12–15,2017,SIOP ABSTRACTS. V. Kobys, V. Konovalenko. Kiev City Oncology Center, Pediatric Oncology, Kiev, Ukraine; 2 Institute of Experimental Oncology, Department of Osteology, Kiev, Ukraine