RU160190U1 - STAND FOR MEASURING THE RIGIDITY OF MODELS OF THE BONE BIOMECHANICAL SYSTEM WITH AN EXTERNAL FIXING DEVICE - Google Patents

Abstract

A stand for measuring the stiffness of models of a bone biomechanical system with an external fixation device, comprising a frame, a fixing plate, a clamping sleeve with the ability to fix a bone simulator with an external fixation device, sensors, a loading device, characterized in that the frame is made in the form of four racks installed in the upper and the lower fixing plates, in which clamping couplings are installed with the possibility of fixing the bone simulator with transosseous osteosynthesis apparatus, the stand contains inductance fixing bones sensors mounted on half-clamps with the possibility of mounting them on a bone simulator, inductive sensors have the ability to connect to an analog-to-digital converter that is connected to a computer, strain gauges that record the applied force are fixed to the lower fixing plate, strain gauges are connected to the dynamometer electronic units, which have the ability to connect to an analog-to-digital converter that is connected to a computer.

Description

The utility model relates to the field of medicine, namely to traumatology and orthopedics, and is intended to measure the rigidity of models of a bone biomechanical system with an external fixation apparatus.

External fixation devices are designed to give the correct location to bone fragments and stabilize the fracture zone until the osteogenesis process is completed. Various mechanical constructions are usually used as external fixation devices, which ensure the long-term elimination of the mobility of bone fragments by means of pins or spokes made of biocompatible materials with biological, chemical, and physical inertness. Mutually exclusive requirements are imposed on the design of external fixation devices. The design of the apparatus should provide the possibility of metered movements for the implementation of axial distraction or compression and angular or translational correction. At the same time, the apparatus should provide sufficient rigidity of the bone biomechanical system, allowing immediate postoperative load perception. The determination of the necessary complex of biomechanical characteristics of a bone biomechanical system with external fixation devices is possible on the basis of experimental measurements of axial, lateral and rotational stiffness under various types of impacts on a special stand.

A known method for evaluating the reliability of fixation of bone fragments on a bone model by connecting fragments using an external or internal fixation device, installing strain gauges in the area of attachment of the device elements and applying a dosed static or dynamic load. After carrying out the studies, the device is dismantled, the bone model is sawn, the strain gauges are calibrated, then the testimony of the strain gauge equipment is decrypted and plots of the forces arising in the bone are constructed as the device elements are tightened and the load is applied. Choose an option that ensures uniform distribution of efforts in the bone (patent RU No. 20177460 C1).

The disadvantage is the need for gluing strain gauges and low accuracy of measurement of displacements.

A device for modeling transosseous osteosynthesis is known, made in the form of a detachable cylinder, the opposing ends of the parts of which are equipped with removable nozzles with risks having comparable surfaces of different configurations, and the bases with supporting platforms, with holes of different diameters made along the perimeter of each part. The nozzles are provided with indicative risks (patent RU No. 107384 U1). The description of the utility model says “... to determine the power and linear parameters of the applied forces, the measuring devices are attached.”, But it is not indicated which measuring devices are used, where and how they are attached.

The device is intended for modeling osteosynthesis techniques.

The closest is a device for studying the rigidity of transosseous osteosynthesis models, containing a bed made in the form of a parallelogram, a fixing panel for fixing the supports of external fixation devices and a clamping sleeve for fixing the bone simulator, a beam with a longitudinal slot for fixing movement indicators, a beam with blocks for modeling loads located on the sides of the bed, tared loads with a cable, movement indicators (patent RU No. 2246139 C2).

The disadvantage of this device is the lack of accuracy, complexity and high complexity of the analytical determination of stiffness, consisting in a large number of experimental studies with the replacement of modules and calibration weights for the selection of parameters of the external fixation apparatus.

To increase accuracy, reduce labor intensity and simplify the process of measuring axial, transverse and rotational stiffness components, a stand for measuring the stiffness of bone biomechanical system models with an external fixation apparatus is proposed, comprising a frame, a fixing plate, an external fixation apparatus, a bone simulator, and a clamping sleeve for fixing a bone simulator , sensors, loading devices. The frame is made in the form of four racks installed in the upper and lower fixing plates, in which there are clamping couplings for fixing the bone simulator with an external fixation device. In the area of a bone fracture, half-clamps are fixed with inductive sensors installed in them, recording the movement of the bone and connected to an analog-to-digital converter and a computer. Strain gauges that record the applied force are fixed on the bottom panel, strain gauges are connected to the dynamometer electronic units, with an analog-to-digital converter, which is connected to a computer that processes the incoming information according to a given program.

Common features of the bed (frame), fixing panel (fixing plates), external fixation apparatus, bone simulator, clamping sleeve for fixing the bone simulator, movement indicators (inductive sensors), calibrated loads (loading devices).

In FIG. 1. depicts a stand for measuring the rigidity of models of a bone biomechanical system with an external fixation device; in FIG. 2 - upper clamping sleeve 4; in FIG. 3 - lower clamping sleeve 5; in FIG. 4 - mounting the strain gauge 12 on the lower fixing plate 3; in FIG. 5 - fastening of inductive displacement sensors 15; in FIG. 6 - fastening of inductive displacement sensors 16; in FIG. 7 is an electronic circuit of the stand.

The stand consists of a frame consisting of four racks 1 installed in the upper fixing plate 2 and the lower fixing plate 3. A clamping sleeve 4 is installed on the upper fixing plate 2, a clamping sleeve 5 is installed on the lower fixing plate 3. It is fixed in the clamping sleeves 4 and 5 bone simulator 6 with an external fixation device for transosseous osteosynthesis, consisting of semirings 7, rods 8, spokes 9. Strain gauges of applied force 10, 11, 12 are fixed on the lower fixing plate (sensor 12 is attached to Fig. 4). On the bone simulator in the fracture area, half-clamps 13, 14 are installed with two inductive sensors of bone movement 15 (compression, bending) and two inductive sensors 16 (torsion) fixed on them (Fig. 5, 6). Loading devices 17, 18, 19, made in the form of a screw pair, act through the strain gauges 10, 11, 12 on the bone simulator 6.

The electronic circuit of the stand is shown in Fig. 7. Strain gauges of effort 10, 11, 12 are connected by wires 20, 21, 22 to electronic blocks of dynamometers EB1, EB2, EB3, which are connected to an analog-to-digital converter (ADC) and then to a computer that processes the incoming information on a given program. Inductive displacement sensors 15, 16 are connected by wires 23, 24, 25, 26 to an analog-to-digital converter (ADC) and then to a computer that processes the incoming information according to a given program. To equip the stand, dynamometers with compression ADC / 2C are installed, which are designed to measure static and slowly changing forces. The dynamometer consists of an elastic element with glued strain gages, power-input elements, an electronic unit and a connecting cable. The principle of operation of the dynamometer is to convert the deformation of the elastic element caused by the action of the applied force to the loading device into an electrical signal. The bone simulator is made of a material having the properties of natural bone, and natural bone can also be used.

The stand works as follows. Assemble the frame of the stand. Strain gauge force sensors 10, 11, 12 are fixed on the lower fixing plate 3, connected with wires 20, 21, 22 to electronic blocks of dynamometers EB1, EB2, EB3, which are connected to an analog-to-digital converter (ADC) and then to a computer. In the clamping sleeves 4 and 5 mounted on the fixing plates 2 and 3, a bone simulator 6 is fixed with an external fixation apparatus for transosseous osteosynthesis. In the area of a bone fracture, half-clamps 13, 14 are fixed, inductive displacement sensors 15, 16 are installed in them, which are connected by wires 23, 24, 25, 26 with an analog-to-digital converter (ADC) and then with a computer.

The load is created by devices 17, 18 (torsion) or 19 (compression, bending) by turning a screw pair, thereby acting through tensometric sensors 10, 11, 12 on the bone simulator 6, which changes position. The values of the loads acting on the bone simulator, and the amount of movement of the bone simulator 6, recorded by strain gauges 10, 11, 12 and inductive sensors 15, 16 are transmitted to the ADC, then to the computer. According to a given program, the computer calculates and displays the dependence of the stiffness on the load in the form of graphs. Based on the constructed graphs, an analysis is carried out and the optimal parameters and type of apparatus for external fixation are determined, which ensures the best combination and fixation of bone fragments.

The bench can be used to measure the rigidity of models of a bone biomechanical system with external fixation devices of various parts and materials. Depending on the purpose of the research, the number of sensors and their installation location may vary.

The use of the bench compared to the prototype will increase the accuracy, reduce the complexity and simplify the process of measuring the axial, transverse and rotational stiffness of various models of the bone biomechanical system with an external fixation device, which will allow you to choose the type and parameters of the external fixation device that provides the best combination, fixation of bone fragments and osteosynthesis method.

Claims (1)

A stand for measuring the stiffness of models of a bone biomechanical system with an external fixation device, comprising a frame, a fixing plate, a clamping sleeve with the ability to fix a bone simulator with an external fixation device, sensors, a loading device, characterized in that the frame is made in the form of four racks installed in the upper and the lower fixing plates, in which clamping couplings are installed with the possibility of fixing the bone simulator with transosseous osteosynthesis apparatus, the stand contains inductance fixing bones sensors mounted on half-clamps with the possibility of mounting them on a bone simulator, inductive sensors have the ability to connect to an analog-to-digital converter that is connected to a computer, strain gauges that record the applied force are fixed to the lower fixing plate, strain gauges are connected to the dynamometer electronic units, which have the ability to connect to an analog-to-digital converter that is connected to a computer.

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