Implanted pumps for accessory circulation should meet the requirement of a minimum continuous service life (8 years). The rotor bearing elements are most critical in terms of continuous service life. This is due to mechan ical wear of bearing elements of axial pumps. There are two approaches to construction of wear resistant bearing elements of axial pumps: 1) lubrication free sliding bear ing elements (Thoratec Corp., Jarvik Heart, Inc.) [1,2]; 2) contact free elements (magnetic suspension) (Berlin Heart GmbH) [3]. There are advantages and disadvan tages in both approaches.Sliding bearing elements are relatively simple and inex pensive in comparison with magnetic suspension [4,5]. The main problem is inability to construct sliding bearings using widely available materials because of biological incompati bility. Therefore, new antifriction materials and friction pairs should be studied for use in implanted mechanisms. These materials should meet the following requirements: low friction coefficient, low wear (assuring requirement of minimum continuous service life), and biocompatibility.The antifriction materials and friction pairs were selected in three stages: laboratory stage, standpoint stage, and experimental stage. The laboratory tests were directed toward increasing wear resistance of biologically compatible materials using wear tight coating. The sec ond stage was directed toward design of an experimental setup for testing axial load. The third stage involved test ing axial pumps in animals. Laboratory Tests of Antifriction Properties of MaterialsPreliminary tests allowed two materials to be select ed for blood axial pumps: CoCrMo alloy and Al2O3 syn thetic sapphire.Special diamond like coating (DLC) improved tribo logical parameters of the materials. DLC was applied using reactive ion rate synthesis (method of physical deposition).CoCrMo alloy and Al2O3 synthetic sapphire were coated using Optimol SRV vibrotribometer in dry friction mode (finger disk scheme) at load 5 25 N. CoCrMo samples coated with diamond like coating, prepared for tests in a vibrotribometer, are shown in Fig. 1. Test condi tions were close to exploitation conditions in terms of pressure, sliding rate, and the absence of lubrication. The laboratory tests determined friction coefficients for the friction pairs of interest.The working chamber of the Optimol SRV vibrotri bometer in tests for tribological parameters of tribological bearing element of the axial pump is shown in Fig. 2.An approach to the design of bearing units for an axial blood pump is suggested in this work. The design of the system places a limitation on the time of continuous pump operation. Antifriction materials for triboengineering elements were selected, and aspects of biological compatibility of such materials are discussed. The tribological elements of the system were tested in vivo and in vitro. Fig. 1. CoCrMo samples coated with diamond like coating.

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Based on the concept of biomechanic and biochemic compatibility of nikelide Ti implants with body tissues the application of devices with form memory effect as well as superelasticity for the treatment of uncomplicated compressive fractures of thoracic and lumbar spine was substantiated. Fixators played the role of so called endoprostheses for the injured posterior ligamentous apparatus resulted from superelasticity. In cases without severe disorders of spine mobility in postoperative period those fixators allowed early activization and rehabilitation of patients. On the basis of clinical outcomes of 32 patients with vertebral body fractures efficacy of posterior fixation by nikelide Ti brackets has been proven.

At the Scientific Research Institute of Emergency Care named after N.V. Sklifosovskiy the modern cruciate ligament implants (France) have been successfully used since 1994. Physical mechanical and deformed characteristics of ligaments of human knee joint and synthetic prostheses of ligaments were tested by machine «Zwick-1464». New original endoprostheses of knee joint ligaments as well as instruments for optimization of the points of entrance and exit within condyles were elaborated. The methods for elimination of different types of knee joint instability in cruciate ligament injury using authors' endoprostheses were worked out. Authors proved that it could improve the functional results of treatment.