Method and device for studying transosseous osteosynthesis model stiffness

FIELD: medicine; medical engineering.

SUBSTANCE: method involves studying transverse longitudinal and rotation stiffness characteristics. The studies are carried out step-by-step from the first order units to complete external fixation apparatus structure. The device has frame and is provided with calibration loads, wire rope, displacement indicators, strip for fastening to loading end of bone imitator fragment, beam for fixing displacement indicators, beams having unit for modeling longitudinal and transverse loadings. The frame is manufactured as parallelepiped. The fixing panel has openings for bone imitator, for fixing external fixation apparatus and yoke connection union and is fixed in end face part of the frame. Beam for fixing displacement indicators has longitudinal slit for fixing the indicators and arranging them on lateral slots in frame base. The beams having unit for modeling rotational, longitudinal and transverse loadings are arranged on lateral frame sides on lateral slots in base.

EFFECT: high vision acuity without applying spectacle-based correction; accelerated treatment course.

2 cl, 16 dwg, 1 tbl

 

The invention relates to medicine, namely to traumatology and orthopedics, and can be used for analytical determination of stiffness models osteosynthesis any external devices.

There is a method of determining the stiffness of the models of transosseous osteosynthesis by Ilizarov [1]. According to the known method ring apparatus that secures the proximal bone fragment, is rigidly fixed to the frame of the test bench. Then to the distal articular end in the transverse direction by means of bagged cargo exert the bias force: first, in the frontal plane, and then in the sagittal plane. The degree of displacement of bone fragments judged in terms of sensors, linear displacement gage installed near the fracture.

The disadvantage of this method and device for its implementation is the low information content.

In addition, an important drawback of all known methods is the lack of a strict designation of the investigated configurations of external fixation devices. It is known that a textual description of the operations of transosseous osteosynthesis, even in the presence of explanatory drawings, is accurate enough, as it leaves considerable scope for interpretation of the data. It is also known that even a slight change in the angle mutually is about the intersection of transosseous elements, the distance between transosseous elements, the diameter of the outer supports, their geometry, etc. significantly affect the performance of the rigidity of osteosynthesis [3]. Thus, when using the same research method, different researchers can get a variety of digital data. It is not possible to compare and analyze the data of different authors.

A known Method for the unified designation of external fixation” [4], which allows to precisely describe the type of transosseous elements, their spatial arrangement, the geometry of the external supports and biomechanically asked the state between them. But none of the known methods for investigating the rigidity of osteosynthesis this method is not used. It does not allow two independent researchers to accurately (identical) to build the model of osteosynthesis. Therefore, the result of the research will inevitably vary and cannot be considered objective. Model Ilizarov confirmed and confirmed its adequacy for the ability to treat functionally. Therefore, a standard design of Ilizarov invited to take for a unit of measure rigidity at the transosseous osteosynthesis.

Closest to the present invention is a method of research models osteosynthesis, involves a study of poperen the th and rotational stiffness characteristics fixation of bone fragments and test bench for its implementation [2].

How is that a hard fix one of the “fragments” in the grip, and for free take a load by means of bagged cargo, explore the offset from the bending load in the frontal and sagittal planes, as well as from turning in a horizontal plane. After that register the amount of displacement of the free “fragment” in place of “break” from the load sensors and compare the values Spitzweg and sizestring of external devices with each other.

The test stand consists of a fixing part (grip), a disk mounted on a fixed “the fragment”, which has two linear displacement sensor. The sensors are connected to a free fragment in the immediate vicinity of “break”to free “the fragment” put bagged cargo.

The disadvantages of this method and device for its manufacture are:

1. The design of the test bench does not allow to investigate the axial stability of the osteosynthesis.

2. The design of the test bench and used the way the experiment is not possible to examine individual modules external device.

Leads to lack of informativeness of the investigated structures.

Insufficient informat what you want to make about the stiffness characteristics of external devices.

The objective is to improve the quality of treatment by selection of an individual device.

Functional unit in the construction of the apparatus for external fixation is the external support pinned it transosseous elements. It is labeled “module of the first order” (M1).

The first-order modules with the same type of transosseous elements (only spokes or rods-screws) taken as a homogeneous first-order modules (Mo). External support, which set forth the various types of external elements (e.g., needle and rod-screw) are combined modules of the first order (M1K).

In accordance with the established biomechanical requirements of each bone fragment in an external device is recorded in one or two modules of the first order. Two modules of the first order, are combined into one subsystem (fixing one bone fragment), labeled “module of the second order” (M2).

Homogeneous second-order modules (Mo) are combined into a single subsystem two homogeneous first-order module. Accordingly, the combined modules of the second order (M2K) are combined into a single subsystem two combined module of the first order.

The modules of the third order for one bone fragment can only speak hypothetically. So what oblem third order (M3) is the full layout of the external device. If there are two bone fragments of the M3-module can be formalized three options:

- M1+M1

M1+M2 (M2+M1)

- M2+M2

Depending on the types used transosseous elements (only spokes, only rods-screws, the combination of pins and rods-screws) M3 formally identified as Mo and MC.

General classification of modules in transosseous osteosynthesis presented in table 1.

Classification of modules external fixation provides the systematic nature of the research, assuming the definition of “white spots” biomechanics of external fixation in the direction from the most studied homogeneous (Spitzweg) modules of the first order (Mo) to the combined modules of the second order (M2K) and a complete layout of the external device (M3). Cross in any of the planes of rotation, the longitudinal stiffness of the bone fragment fixation (bone simulator) as external modules and the layout in General is provided by the use of biomechanical stand. Its design features allow you to easily and accurately investigate the rigidity of external modules, and a complete layout of the apparatus for external fixation in all six degrees of freedom.

To identify weak links in the layout of the investigated external device it is being researched phased towards the situation from the characteristics of individual supports to complete the layout.

High accuracy, reproducibility and validation of data obtained by any researcher also ensured by the use of a Method of unified designation of external fixation”.

The proposed stand for biomechanical studies (figure 1) consists of the frame 1, the fixing panel - 2, clamp couplings, two beams with block - 5, one beam for mounting sensors - 3, two sensors linear displacement of 6, set of bagged cargo.

Base stand is made of steel area, rigidly connected among themselves in the area of the joints and takes the form of a parallelepiped.

The use of steel area provides high rigidity and, in addition, the edges of the area is convenient to use as a “guide” for beams commit sensors, beams with block rotation, axial (compression, distraction and lateral loads.

The shape of the box is chosen because it provides convenience for fixing of external modules and bone fragments, devices for bias application loads, measurement of displacements. In addition, the shape of a parallelepiped has its own sufficient rigidity.

The locking panel of the stand (figure 2) rigidly attached to the end of the bed. In the center of the fixing panel there is a hole. Besides him, fiksiruya panel has radial orifices. The hole is designed to hold it vistiesako the end of the bone model. Radial orifices are designed for fixing by means of bolts (clamps) external supports external fixation devices. Has holes for fixing the clamping couplings in figure 3.

The clamping sleeve (3) is rigidly attached to the locking bar stand. Consists of a disk (Fig) and bracket (Fig). The clamping sleeve is functionally designed for rigid fixation of the bone model to the fixing panel stand. Drive (Fig) clamping coupling has holes for attaching bolts brackets and attaching to the fixing panel stand. Bracket (Fig) consists of two symmetrical parts, connected by bolts.

The stand is equipped with a beam for fixing indicators linear (figure 5). Beam with transverse grooves made with each of its ends, can be moved in the plane of the base frame. Throughout the length of the beam is made of a longitudinal slot for fixing the legs indicators (sensors). The presence of transverse slots and a longitudinal slot in the beam makes it possible to wrap the sensor in any selected position.

To allow the simulation of rotary, axial (compression, distraction and lateral loads stand is equipped with two beams with a block (6). Beam with transverse grooves made with ka the instrument from its ends, can be moved in the lateral plane of the bed. On one end of the beam there is a thread with nut 2. By tightening the nuts beam, due to the wedging firmly secured to the frame of the stand. The beam can move in the longitudinal direction of the block consisting of the clutch 4 and the rod 5 with the roller 6. The clutch 4 may reciprocating travel along beam 1. To lock in the selected position serves as the bolt 7.

Use the method and the device are as follows. The first stage determines the stiffness of the modules of the first and second order of the investigated device. The algorithm experiment for M1 and M2 are equal.

The study of longitudinal stiffness M1 and M2 (Fig.7, 8).

For studies of the longitudinal stiffness of the modules required equipment, see figure 7, 8.

External support of the investigated module is firmly fixed to the fixing panel 2 (figure 1). To inundate the end securing metal lath. When ″compression″ beams with a block down so that the generated force loads are parallel to the axis of the bone model (Fig.7). Accordingly, when ″distraction″ (Fig) beams with blocks down on the opposite side from the fixed to the simulator strap. As shown in Fig.7 and 8, the end face of the free end of the bone simulator fail indicator linear displacements. By Taree is avannah 50 N loads applied to the monitored load (for example, “distraction”) with its gradual increase: 50 N 100 N 150 N 200 N, etc. Record sensor values showing the amount of displacement of the bone model depending on each increment of load. The experiment stopped when the indicator will show the amount of displacement of the bone model by 1.2-1.5 mm Reinstalling blocks, explore the rigidity of the module from loading the compression. The experience is repeated three times and calculate the average magnitude of displacement of the bone model depending on each step of the load. Control is recognized as the amount that causes the offset value of 1 mm.

Step load size 50 N selected imperiously, in experimental substantiation of the method of the experiment. It was found that in the study of most first captured by the displacement sensors, which are significant for reparative osteogenesis occurred at this load. In the study designs that provide low rigidity of osteosynthesis, the magnitude of the step load can be reduced.

The maximum value of the indicator 1.2-1.5 mm was chosen due to the fact that the displacement of the fragments in large numbers taken impractical for use in the clinic, because the load is causing this shift, not favorably affect the formation of callus.

Research rotation as is dosti M1 and M2 (figure 9).

For this series of experiments use the equipment presented on Fig.9.

External support of the investigated module is firmly fixed to the fixing panel 2 (figure 1). At the free end loaded fragment simulator bone mount metal lath (Fig.9) at a distance of 50 mm from the plane of support (in M2 from the distal support). In point a and b, which are equidistant from the center of the model bone, down two sensors. The recommended distance between the sensors L=100 mm Load attaching points A1 and B2 of the metal lath. Points A1 and B2 are also equidistant from the center of the bone model. The recommended distance between the points A1 and B2, h=200 mm Rope fixed to the blade at the point A1, thrown through the block, which is rigidly attached to the frame of the stand so that the roller is located 30 mm above the metal bracket. The second cable is attached to a metal strip at the point B1.

Through a tared 10 N loads, simultaneously on both sides, put the load with its gradual increase: 20 N - 40 N - 60 N - 80 N etc.

Obtained by the sensors of the figures of the movement (the movement is labeled “V”) at the points a and b from each increment of load (VAiand VBi, where i is the number of the applied load), is used for further processing.

According to the formula tgαi=57,3 (VAi+VBi)/L (where L p is sloanie between points a and b) calculate the angle of the bone model.

The experiment is stopped at the angular offset of the tgαi=1.2 to 1.5 degrees. The experience is repeated three times and calculate the average magnitude of the load, which causes a displacement of the bone model on tgαi=1 degree.

The study of transverse stiffness M1 and M2

For this series of experiments use the equipment presented on figure 10 and 11.

The study of transverse stiffness in the sagittal plane

For loading in the sagittal plane (For Me - in solution angle 60°) use the diagram of the experiment in figure 10. To the free end of the bone model down two indicator linear gage at a distance of a=40 mm from each other. The distance from the ring support (point O) to the first indicator b=40 mm, in the study of M2 point O is in the plane of the distal support. Through a tared 10 N loads applied load in the sagittal (relative to the orientation of M1 and M2) plane with its gradual increase: 10 N - 20 N - 30 N - 40 N and so the Load is applied at a distance of 100 mm from the conventional point O.

Write values of the sensors showing the offset bone simulator (V) at the points a and b depending on each increment of the load: VAiand VBi(i is the number of applied load).

The angle of rotation of the simulator the spine depending on each increment of load is determined by the formula tgϕ i=57,3 (VAi-VBi)/a.

The experiment is stopped at the angular offset of the tgαi=1.2 to 1.5 degrees.

The experience is repeated three times and calculate the average magnitude of the load, leading to displacement of the bone model on tgαi=1 degree.

The study of transverse stiffness in the frontal plane

For the application of the load in the frontal plane (For Me - in solution angle 30°) use the scheme of experiment 11. In the study of rigidity in the frontal plane can not change the location of the fixation of the model after the experiment in the sagittal plane, and you can simulate the load direction using the blocks. The algorithm experiment similar to that described above for the load module in the sagittal plane.

The research module in any other intermediate transverse plane is carried out with the difference that the model is fixed to the fixing panel stand in the position selected for the study. The location of the sensors, distance and volume of the applied load, and the calculations are similar to the study in the sagittal plane.

The second stage of the experiment is the study module 3-th order (M3). The algorithm experiment for M3 is as follows.

The study of longitudinal stiffness M3 (Fig and 13).

For research about Olney stiffness modules required equipment, shown in Fig, 13.

Free portion of the proximal fragment 1 (Fig and 13) is fixed in the clamping sleeve 2 (Fig and 13), which is bolted rigidly attached to the fixing panel stand 3 (Fig. and 13). Free loaded (distal) end securing metal lath 4 (Fig and 13). When “compression” beams with a block down so that the generated force loads are parallel to the axis of the bone model. Accordingly, when the “distraction” (Fig) beams with 5 blocks down on the opposite side from the fixed to the simulator strap. As shown in Fig and 13, the end face of the free end of the bone simulator fail indicator linear displacements. Through a tared 50 N loads applied to the monitored load (for example, “distraction”) with its gradual increase: 50 N 100 N 150 N 200 N, etc. Record sensor values showing the amount of displacement of the bone model depending on each increment of load. The experiment stopped when the indicator will show the amount of displacement of the bone model by 1.2-1.5 mm Reinstalling blocks, explore the rigidity of the module from loading the compression. The experience is repeated three times and calculate the average magnitude of the applied load that causes displacement of the bone model size 1 mm.

Studies of rotational stiffness M3 (Fig).

For p is Ogadenia this series of experiments used equipment, presented at Fig.

Free portion of the proximal fragment is similar to studies of longitudinal, transverse rigidity is fixed in the clamping sleeve, which is bolted rigidly attached to the fixing panel stand. At the free end loaded fragment simulator bone mount metal lath 1 (Fig) at a distance of 50 mm from the plane of the distal support. In point a and b, which are equidistant from the center of the model bone, down two sensors. The recommended distance between the sensors L=100 mm Load attaching points A1 and B2 of the metal lath. Points A1 and B2 are also equidistant from the center of the bone model. The recommended distance between the points A1 and B2, h=200 mm Rope fixed to the blade at the point A1, thrown through the block, which is rigidly attached to the frame of the stand so that the roller is located 30 mm above the metal bracket. The second cable is attached to a metal strip at the point B1.

Through a tared 10 N loads, simultaneously on both sides, put the load with its gradual increase: 20 N - 40 N - 60 N - 80 N etc.

Obtained by the sensors of the figures of the movement (the movement is labeled “V”) at the points a and b from each increment of load (VAiand VBi, where i is the number of the applied load), is used for further processing.

According to the formula tgαi =57,3 (VAi+VBi)/L (where L is the distance between points a and b) calculate the angle of the bone model.

The experiment is stopped at the angular offset of the tgαi=1.2 to 1.5 degrees.

The experience is repeated three times and calculate the average magnitude of the load, which causes a displacement of the bone model on tgαi=1.

The study of transverse stiffness MOH

For this series of experiments use the equipment presented on Fig and 16.

The study of transverse stiffness to the MOH in the sagittal plane

For loading in the sagittal plane (For Me - in solution angle 60° base supports) using the scheme of the experiment on Fig. To the distal free end of the bone model down two sensor linear displacement gage at a distance of a=40 mm from each other. The distance from the ring support (point O) to the first indicator b=40 mm By means of calibrated by 10 N loads applied load in the sagittal (relative to the orientation MA) plane with its gradual increase: 10 N - 20 N - 30 N - 40 N and so the Load is applied at a distance of 100 mm from the conventional point O, located in the plane of the distal support. Write values of the sensors showing the offset bone simulator (V) at the points a and b depending on each increment of the load is: V Aiand VBi(i is the number of applied load).

The angle of the bone model depending on each increment of load is determined by the formula tgϕi=57,3 (VAi-VBi)/a.

The experiment is terminated upon the occurrence of angular displacement tgαi=1.2 to 1.5 degrees.

The experience is repeated three times and calculate the average magnitude of the load, leading to displacement of the bone model on tgαi=1 degree.

The study of transverse stiffness M3 in the frontal plane

For the application of the load in the frontal plane (For Me - in solution angle 30° base supports) using the scheme of the experiment on Fig. In the study of rigidity in the frontal plane can not change the location of the fixation of the model after the experiment in the sagittal plane, and you can simulate the load direction, using the blocks. The algorithm experiment similar to that described above for the load module in the sagittal plane.

The research module in any other intermediate transverse plane is carried out with the difference that the model is fixed to the fixing panel stand in the position selected for the study. The location of the sensors, distance and volume of the applied load, and the calculations are similar to the study in the sagittal plane.

So what Braz, the proposed method research stiffness models of transosseous osteosynthesis and device for its implementation allows for the study of rigidity models of external modules and full configurations of external devices, algorithm standard actions determine the basic characteristics of rigidity. Device biomechanical stand allows you to explore how the modules of transosseous osteosynthesis and full layout of the apparatus for external fixation in all six degrees of freedom.

To identify weak links in the layout of the investigated external device it is being researched in stages in the direction from the characteristics of individual supports to complete the layout. Thus the task of improving quality of care through the selection of an individual device.

Sources of information

1. Collars A.A. Clinical and experimental aspects of the treatment of diaphyseal fractures of the forearm method of transosseous osteosynthesis: Dis.... Kida. the honey. Sciences. - Stavropol, 1984. - 137 C.

2. Novoselov K.A. Rationale and development of new methods of surgical treatment of closed diaphyseal fractures of the femur: Dis.... Kida. the honey. Sciences. - Leningrad, 1988. - S-102 - (219 S.).

3. Shevtsov V.I., Nemkov V., Sklar L.V. Ilizarov. Biomechanics: barrow, 1995 - 165 C.

4. Barabash A.P., Solomin L.N. “Esperan what about the” holding of transosseous elements when osteosynthesis by Ilizarov: Novosibirsk, 1997. - 187 S.

METHOD RESEARCH STIFFNESS MODELS of EXTERNAL OSTEOSYNTHESE AND DEVICE FOR ITS IMPLEMENTATION

Table 1.

Modules in transosseous osteosynthesis
M1 - the first-order modulesM2 - second-order modules
Mo - homogeneous first-order modulesMo - homogeneous second-order modules
M1K - combined first-order modulesM2K - composite second-order modules
M3 - modules third-order
Mo - homogeneous modules third-order
MC - combined modules of the third order

1. Method research stiffness models of transosseous osteosynthesis by examining transverse and rotational characteristics, characterized in that it further examine the longitudinal characteristics of rigidity, and the research carried out in stages from the first-order modules to complete the layout of the external fixation device.

2. Device for determination of the rigidity models of transosseous osteosynthesis containing a frame, characterized in that it has bagged goods, rope, indicators movement, strap for the rise to inundate the end of the section of the bone model, the locking panel clamp coupling for fixing bone simulator, beam to lock indicators movement, beams with blocks for modeling rotational, longitudinal and transverse loads, the bed is made in the form of a parallelepiped, the locking panel is made with holes for bone simulator, fixing supports external fixation devices and clamping sleeve and fixed to the end part of the base, a beam for fixing indicators of movements performed with a longitudinal slot for capturing and placed at the base of the bed on the side grooves, and beams with blocks for modeling rotational, lateral and longitudinal loads are placed on the sides of the bed on the side grooves.



 

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