Shevchenko I. Modular arthroplasty in the treatment of malignant tumors of the distal femur

Object: a surgery treatment of patients with malignant tumors of the distal femur with use of modular replacement. Purpose: to improve the efficiency of surgical treatment of patients with malignant tumors of the distal femur by founding and developing methods for replacement of postresection osteoarticular defects with modular endoprostheses based on experimental and clinical studies. Methods: clinical, roentgenological, computer and magnetic resonance tomography, pathomorphologic, mathematical modeling using finite element method, statistical. For the first time using the method of mathematical modeling a stress-strain state of the system "prosthesis - bone" was analyzed by the example of the endoprosthesis of the distal femur. It allowed to determine the highest values of the stress under axial load to intramedullary prosthesis stem along its entire length with maxima on its base and attachment point of prosthesis module with the stem depending on the stem inclination angle, its length and size of the prosthesis body. The design of the modular implant of the distal femur has been optimized. The fixation possibilities in the system "prosthesis - bone" were increased by the use of additional extracortical fixation of prosthesis stem, conical form of stem, cementless fixation by the ceramic coating. First the method of individual modular replacement for the postresection distal femur defects which involves using additional extracortical fixation of prosthesis stem was developed for patients with malignant tumors. Indications and contraindications for individual modular replacement of the distal femur were identified. Technique of this kind of surgery after the removal of the malignant bone tumors of extremities has been proposed. This helps to obtaining positive oncologic and functional orthopedic outcomes, decrease of percent postoperative complications and improves long-term outcomes of these patients. Increasing the "survival time" of modular prostheses with improved design features achieved by a combined fixing of prosthesis stem, modularity and the use of a hinged knee prosthesis unit. Results of the study are introduced into clinical practice in SI "Sytenko Institute of Spine and Joints Pathology NAMS of Ukraine", MHA "Kharkiv Regional Clinical Trauma Hospital", MHA "Regional Clinical Hospital - Center for emergency medical care and disaster medicine", MHA "Kharkiv City Hospital № 18", as well as in the educational process of the Department of Traumatology and Orthopedics of Kharkiv National Medical University Ministry of Health of Ukraine. Traumatology and Orthopaedics.