A device and method for applying compressive load to the irregular and complete surface of bone cartilage

Abstract

A device and method for applying compressive load to the irregular complete surface of bone cartilage, relating to the fields of biomechanics and mechanics. It comprises a cylindrical loading cylinder, a cross-shaped loading slider, a base, a customized mold, a U-shaped clamp, a positioning splint, and a connector. The bottom of the cylindrical loading cylinder is provided with a base that matches it, and the inner wall of the cylindrical loading cylinder is provided with a rectangular sliding guide rail, which matches the cross-shaped loading slider. The lower end of the cross-shaped loading slider is provided with a U-shaped clamp, and bolts and rectangular guide rails are installed on one side of the U-shaped clamp, and the bolts and rectangular guide rails are connected to the positioning splint. It is conducive to achieving full contact between the surface of the bone cartilage and the surface of the customized mold, so as to achieve the effect of simulating the interaction between the joint surfaces of animals; it is conducive to simulating the contact and force conditions of the surface of the articular cartilage when it is subjected to a compressive load in vivo, and plays a positive role in promoting in vitro cartilage experiments.

Description

Technical Field

[0001] The present invention relates to the field of biomechanics and mechanics, and specifically to a device and method connected to a testing machine for applying a compressive load to an irregular complete surface of bone cartilage, and is particularly suitable for simulating in vitro the compressive load that an irregular complete surface of a joint is subjected to in vivo. Background Art

[0002] Articular cartilage is a nonlinear viscoelastic material covering the surface of joints, and its structure and function are the result of adapting to the mechanical environment. The growth, development and maintenance of normal physiological functions of cartilage require the action of load. The stress state of articular cartilage is crucial to the normal movement and load-bearing capacity of the joints, and is also closely related to the pathological changes of the joints. Therefore, studying the mechanical properties of articular cartilage can well express the metabolic mechanism of cartilage tissue, and can help further reveal cartilage damage, providing guidance for the treatment of such diseases and the cultivation of artificial cartilage.

[0003] Various mechanical loading experiments have shown that articular cartilage has complex material properties and exhibits nonlinear mechanical behavior. Influencing factors include whether the cartilage is free from the subchondral bone; whether the depth-dependent characteristics of the cartilage are considered; whether the cartilage is in a compressed or stretched state; the strength and rate of the applied mechanical load, etc. For example, articular cartilage separated from the subchondral bone and articular cartilage attached to the subchondral bone exhibit different material responses to the same mechanical load.

[0004] However, in existing scientific research experiments, when applying static loads or corresponding dynamic loads to osteocartilage in vitro, the surface of the cartilage is usually removed and the subchondral bone is excised, so that the surface of the osteocartilage can become very flat, and then the compression load loading experiment is carried out. Such surface removal and deep peeling of the cartilage greatly destroy the organizational structure of the osteocartilage. When the corresponding mechanical loading is carried out, the measured results are greatly different from the properties of the osteocartilage itself.

[0005] Therefore, when applying bionic compressive loads to osteocartilage in vitro to study the material properties of articular cartilage, the form of the compressive load on the osteocartilage explant in vitro should be closer to the form of the compressive load on the osteocartilage in vivo, and the integrity of the osteocartilage structure should be ensured, so that more accurate data patterns can be obtained. Summary of the invention

[0006] Technical problem: In response to the problems existing in the prior art, the purpose of the present invention is to provide a device and method connected to a testing machine for applying compressive load to the irregular complete surface of osteocartilage, thereby solving the problem that the irregular complete surface of joint osteocartilage cannot fully simulate the compressive mechanical load it is subjected to in vivo in vitro.

[0007] Technical solution: To achieve the above technical purpose, the present invention provides a device connected to a testing machine for applying a compressive load to an irregular and complete surface of bone cartilage, comprising a cylindrical loading cylinder, a cross-shaped loading slider, a base, a customized mold, a U-shaped clamp, a positioning splint, and a connector. The bottom of the cylindrical loading cylinder is provided with a base that is matched with it through a thread, and a customized mold is assembled on the base. By disassembling the base, different customized molds can be replaced according to the different surface shapes of the bone cartilage.

[0008] The inner wall of the cylindrical loading cylinder is provided with two sets of symmetrical rectangular sliding guide rails, which cooperate with the cross-shaped loading slider. The length of the two sets of symmetrical rectangular sliding guide rails reaches 2 / 3 of the length of the cylindrical loading cylinder, which can realize the full stroke loading of the loaded object in the cylinder. The cross-shaped loading slider can slide through the slide rails on the cylindrical loading cylinder. At the same time, under the restriction of the two sets of symmetrical rectangular sliding guide rails, the cross-shaped loading slider will not shake or deviate left and right, which can make the loading process more accurate.

[0009] The lower end of the cross-shaped loading slider is connected to a U-shaped clamp, and a bolt and a set of rectangular guide rails are installed on one side of the U-shaped clamp. The bolt and the rectangular guide rail are connected to the positioning clamp. The positioning clamp can be moved by rotating the bolt. By moving the positioning clamp, the bone cartilage can be clamped by cooperating with the U-shaped clamp and the positioning clamp.

[0010] A customized mold is provided in the cylindrical loading cylinder and on the base. The concave surface of the customized mold is obtained by 3D printing or high-temperature melting according to the surface of the bone cartilage. The concave surface of the obtained customized mold can fully contact the surface of the bone cartilage used in the loading process, thereby achieving the effect of simulating the real contact in the joint body by the contact between the irregular surface of the bone cartilage and the surface of the customized mold;

[0011] The cross-shaped loading slide block is provided with a connecting hole and a positioning bolt on its upper side, and the connecting piece is connected to the connecting hole and fixed by the positioning bolt. The connecting piece can be replaced according to the different shapes of the fixture on the testing machine.

[0012] The processing method of the customized mold includes but is not limited to melt solidification molding, 3D printing or laser sintering, and the processing materials include but are not limited to paraffin, engineering plastics, titanium alloy, cobalt-chromium alloy, resin, collagen or polymer materials.

[0013] Beneficial effects:

[0014] The present invention is provided with a customized mold designed according to the irregular surface of osteocartilage, which can achieve full contact between the surface of the customized mold and the surface of osteocartilage, thereby simulating the contact between osteocartilage in the joints of animals; by loading the osteocartilage with a compressive load, the contact and force conditions of the irregular complete surface of the osteocartilage when subjected to a compressive load in vivo can be more realistically simulated in vitro: thereby being able to more accurately simulate the stress and strain changes of the osteocartilage when subjected to a compressive load in vivo; by designing the customized mold to contact the irregular surface of the osteocartilage, the experimental operations of removing the cartilage surface and performing deep cartilage peeling to make the loading surface flat during compression loading are avoided, thereby ensuring the integrity of the cartilage structure; by designing the customized mold to mechanically load the compressive load with the irregular surface of the osteocartilage, a large area of ​​the osteocartilage can be loaded with a compressive load without damaging the surface of the osteocartilage, thereby making the compression loading experiment closer to the actual force compression process of the osteocartilage in the joints in vivo. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the load loading device of the present invention;

[0016] Figure 2 is an overall cross-sectional schematic diagram of a load-loading device of the present invention;

[0017] Figure 3 It is a schematic diagram of the structure of a cross-shaped loading slider of a load loading device of the present invention;

[0018] Figure 4 It is a schematic diagram of the combined structure of a cross-shaped loading slider and a U-shaped clamp of a load loading device of the present invention;

[0019] Figure 5 The U-shaped clamp structure of the load loading device of the present invention is schematically shown. Figure Ⅰ ;

[0020] Figure 6 The U-shaped clamp structure of the load loading device of the present invention is schematically shown. Figure II ;

[0021] In the figure: 1-cylindrical loading cylinder, 2-cross-shaped loading slider, 3-rectangular sliding guide, 4-customized mold, 5-base, 6-bone cartilage model, 7-positioning splint, 8-bolt, 9-U-clamp, 10-connector, 11-positioning bolt, 12-connecting hole, 13-positioning bolt hole, 14-rectangular guide, 15-concave surface, 16-surface of bone cartilage. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] See also Figures 1 to 6 In an embodiment of the present invention, a device connected to a testing machine for applying a compressive load to an irregular and intact surface of bone cartilage is provided. Figure 1 Figure and Figure 2 As shown, it includes a cylindrical loading cylinder 1, a cross-shaped loading slider 2, a base 5, a customized mold 4, a U-shaped clamp 9, a positioning clamp 7, and a connecting piece 10. The bottom of the cylindrical loading cylinder 1 is provided with a base 5 matched with it through a thread, and the customized mold 4 is assembled on the base 5. By disassembling the base 5, different customized molds 4 can be replaced according to the different shapes of the surface 16 of the bone cartilage.

[0025] The inner wall of the cylindrical loading cylinder is provided with two sets of symmetrical rectangular sliding guides 3, which cooperate with the cross-shaped loading slider 2. The length of the two sets of symmetrical rectangular sliding guides 3 reaches 2 / 3 of the length of the cylindrical loading cylinder, which can realize the full stroke loading of the loaded object in the cylinder. The cross-shaped loading slider 2 can slide through the rectangular sliding guides 3 on the cylindrical loading cylinder. At the same time, under the restriction of the two sets of symmetrical rectangular sliding guides 3, the cross-shaped loading slider 2 will not shake or deviate left and right, which can make the loading process more accurate.

[0026] like Figure 4 As shown, the lower end of the cross-shaped loading slider 2 is connected to a U-shaped clip 9. Figure 5 As shown, a bolt 8 and a set of rectangular guide rails 14 are installed on one side of the U-shaped clamp 9, and the bolt 8 and the rectangular guide rail 14 are connected to the positioning splint 7. The positioning splint 7 can be moved by rotating the bolt 8, and the positioning splint 7 can be moved to clamp the bone cartilage through the cooperation of the U-shaped clamp 9 and the positioning splint 7.

[0027] like Figure 2As shown, a customized mold 4 is provided inside the cylindrical loading cylinder 1 and on the base 5. The concave surface 15 of the customized mold is obtained by 3D printing or high-temperature melting according to the surface 16 of the osteocartilage. The concave surface 15 of the obtained customized mold 4 is in full contact with the surface 16 of the osteocartilage used in the loading process.

[0028] like Figure 3 and Figure 4 As shown, the cross-shaped loading slide block 2 is provided with a connecting hole 12 on its upper side, a positioning bolt hole 13 and a positioning bolt 11 are provided on one side of the connecting hole, and a connecting member 10 is connected to the connecting hole 12 and fixed by the positioning bolt 11. The connecting member 10 can be replaced according to the different shapes of the fixture on the testing machine.

[0029] The processing methods of the customized mold include melt solidification molding, 3D printing or laser sintering, and the materials used to make the customized mold include paraffin, engineering plastics, titanium alloy, cobalt-chromium alloy, resin, collagen and polymer materials.

[0030] A method for applying a compressive load to an irregular complete surface of bone cartilage by connecting it to a testing machine, comprising: fixing a customized mold in a cylindrical loading tube 1 and on the upper side of a base 5, and screwing the base 5 and the cylindrical loading tube 1 together by threads; fixing the prepared bone cartilage on the U-shaped clamp 9 by means of a U-shaped clamp 9 and a positioning clamp 7; fixing the prepared bone cartilage on the U-shaped clamp 9 by means of a U-shaped clamp 9 and a positioning clamp 7; selecting a suitable loading connector 10 according to the loading end of the testing machine, connecting the circular end of the connector 10 to the connecting hole 12 on the upper side of a cross-shaped loading slider 2, and fixing it by means of a positioning bolt 11, connecting the other end of the connector to the loading end of the compression testing machine, connecting the base 5 to the other end of the compression testing machine, and then applying a compressive load to the irregular complete curved surface of the bone cartilage.

[0031] The method of the present invention is further described below using the customized mold 4 as paraffin material, and the specific operation steps are as follows:

[0032] Step 1: melt the heated paraffin and inject it into the cylindrical loading tube 1, and the height of the paraffin in the cylindrical loading tube 1 reaches between 1 / 5 and 1 / 4 of the overall tube height.

[0033] Step 2: Fix the prepared bone cartilage on the U-shaped clamp 9 through the U-shaped clamp 9 and the positioning splint 7.

[0034] Step 3: When the temperature of the paraffin in the cylindrical loading tube 1 drops to about 45°C, the paraffin is not completely hardened at this time, push the U-shaped clamp 9 and the cross-shaped loading slider 2 that clamp the cartilage into the tube from the upper side of the cylindrical loading tube 1, and press until the paraffin completely wraps the surface of the cartilage.

[0035] Step 4: After the paraffin is cooled, take the cross-shaped loading slider 2 out of the cylindrical loading tube 1.

[0036] Step 5: According to the loading end of the test machine, select a suitable loading connector 10, connect the circular end of the connector 10 to the connecting hole 12 on the cross-shaped loading slider, and fix it with the positioning bolt 11. The other end of the connector is connected to the loading end of the compression tester, the base 5 is connected to the other end of the compression tester, and then the irregular complete curved surface of the bone cartilage is loaded with a compressive load.

[0037] Different from the above embodiments, if the customized mold 4 of the present invention is made of engineering plastics, resin, polymer materials, etc., the specific operation steps are as follows:

[0038] Step 1: Scan the osteochondral model using CT scanning.

[0039] Step 2: Use modeling software to model the osteochondral data obtained from CT scanning, and obtain a mold surface that matches the cartilage surface through model conversion.

[0040] Step 3: Adjust the mold surface so that the circumferential size of the mold is consistent with the size of the cylindrical loading cylinder 1 , and the height of the mold is 1 / 4 of the height of the cylindrical loading cylinder 1 .

[0041] Step 4: Use 3D printing technology to print the modeled mold 4.

[0042] Step 5: Load the printed mold 4 into the cylindrical loading tube 1, and then the irregular complete curved surface of the bone cartilage can be loaded with a compressive load.

[0043] Further different from the above embodiments, when the customized mold 4 of the present invention is made of titanium alloy, the specific operation steps are as follows:

[0044] Step 1: Scan the osteochondral model using CT scanning.

[0045] Step 2: Use modeling software to model the osteochondral data obtained from CT scanning, and obtain a mold surface that matches the cartilage surface through model conversion.

[0046] Step 3: Process the mold surface to obtain processing information of each layer of the mold. The circumferential size of the mold is consistent with the size of the cylindrical loading cylinder 1, and the height of the mold is 1 / 4 of the height of the cylindrical loading cylinder 1.

[0047] Step 4: Lay titanium powder on the forming workbench and perform laser sintering.

[0048] Step 5: The sintered mold 4 is loaded into the cylindrical loading cylinder 1, and then the irregular complete curved surface of the bone cartilage can be loaded with a compressive load.

[0049] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention, and the contents not described in detail in this specification shall belong to the prior art known to professional and technical personnel in the field.

Claims

1. A device for applying compressive load to the irregular intact surface of bone cartilage, characterized in that: It comprises a cylindrical loading cylinder (1), a cross-shaped loading slider (2), a base (5), a customized mold (4), a U-shaped clamp (9), a positioning clamp (7), and a connecting piece (10), characterized in that: the bottom of the cylindrical loading cylinder (1) is provided with a base (5) matched with it, two groups of symmetrical rectangular sliding guide rails (3) are provided on the inner wall of the cylindrical loading cylinder (1), the two groups of symmetrical rectangular sliding guide rails (3) are matched with the cross-shaped loading slider (2), the lower end of the cross-shaped loading slider (2) is provided with a U-shaped clamp (9), one side of the U-shaped clamp (9) is installed with a bolt (8) and a rectangular guide rail (14), the bolt (8) and the rectangular guide rail (14) are connected with the positioning clamp (7), and the positioning clamp (7) and the U-shaped clamp (9) are matched to clamp the bone cartilage model (6); A custom mold (4) is fixed inside the cylindrical loading cylinder (1) and on the upper side of the base (5), and the concave surface (15) of the custom mold (4) is designed based on the surface (16) of the osteochondral model, and the concave surface (15) is in full contact with the surface (16) of the osteochondral used in the loading process; A connecting hole (12) is provided on the upper side of the cross-shaped loading slide block (2), a positioning bolt hole (13) and a positioning bolt (11) are provided on one side of the connecting hole, and the connecting piece (10) is connected to the connecting hole (12) and fixed by the positioning bolt (11).

2. The device for applying compressive load to the irregular intact surface of bone cartilage according to claim 1, characterized in that: The length of the two sets of symmetrical rectangular sliding guide rails (3) reaches 2 / 3 of the length of the cylindrical loading cylinder, thereby achieving full-stroke loading of the object being loaded in the cylinder.

3. The device for applying compressive load to the irregular intact surface of bone cartilage according to claim 1, characterized in that: The cross-shaped loading slide block (2) slides through the rectangular sliding guide rail (3) on the cylindrical loading cylinder, and under the restriction of the two sets of symmetrical rectangular sliding guide rails (3), no left-right shaking or deviation occurs.

4. A method for applying a compressive load to an irregular intact surface of bone cartilage, implemented by the device according to any one of claims 1 to 3, characterized in that The steps are as follows: a customized mold is fixed inside a cylindrical loading cylinder (1) and on the upper side of a base (5), and the base (5) and the cylindrical loading cylinder (1) are screwed together by means of threads; the prepared bone cartilage is fixed on the U-shaped clamp (9) by means of a U-shaped clamp (9) and a positioning clamp (7); the prepared bone cartilage is fixed on the U-shaped clamp (9) by means of a U-shaped clamp (9) and a positioning clamp (7); according to the loading end of the testing machine, a suitable loading connector (10) is selected, the circular end of the connector (10) is connected to the connecting hole (12) on the upper side of the cross-shaped loading slider (2), and fixed by means of a positioning bolt (11), the other end of the connector is connected to the loading end of the compression testing machine, the base (5) is connected to the other end of the compression testing machine, and then the irregular complete curved surface of the bone cartilage is subjected to a compressive load.

5. The method for applying compressive load to the irregular intact surface of bone cartilage according to claim 4, characterized in that: The customized mold is formed by 3D printing, laser sintering or high-temperature melting; the materials used for the customized mold include paraffin, titanium alloy, cobalt-chromium alloy, stainless steel, aluminum alloy, ceramics, graphene or polymer materials.

6. The method for applying compressive load to the irregular intact surface of bone cartilage according to claim 5, characterized in that: The steps for customizing the mold (4) to be made of paraffin wax are as follows: Step 1: melt the heated paraffin and inject it into the cylindrical loading tube (1), and the height of the paraffin in the cylindrical loading tube (1) reaches between 1 / 5 and 1 / 4 of the overall tube height; Step 2: Fix the prepared bone cartilage on the U-shaped clamp (9) through the U-shaped clamp (9) and the positioning splint (7); Step 3: When the temperature of the paraffin in the cylindrical loading cylinder (1) drops to about 45°C, the paraffin is not completely hardened at this time, and the U-shaped clamp (9) holding the cartilage and the cross-shaped loading slider (2) are pushed into the cylinder from the upper side of the cylindrical loading cylinder (1) and pressed until the paraffin completely covers the surface of the cartilage; Step 4: After the paraffin has cooled, remove the cross-shaped loading slider (2) from the cylindrical loading cylinder (1); Step 5: Select a suitable loading connector (10) according to the loading end of the testing machine, connect the circular end of the connector (10) to the connecting hole (12) on the upper side of the cross-shaped loading slider (2), and fix it with a positioning bolt (11). Connect the other end of the connector to the loading end of the compression testing machine, connect the base (5) to the other end of the compression testing machine, and then apply a compressive load to the irregular complete curved surface of the bone cartilage.

7. The method for applying compressive load to the irregular intact surface of bone cartilage according to claim 5, characterized in that: The custom mold (4) is made of polymer material, and the specific operation steps are as follows: Step 1: Scan the osteochondral model using CT scanning; Step 2: Use modeling software to model the osteochondral data obtained from CT scanning, and obtain a mold surface that matches the cartilage surface through model conversion; Step 3: Adjust the mold surface so that the circumference of the mold is consistent with the size of the cylindrical loading cylinder (1), and the height of the mold is 1 / 4 of the height of the cylindrical loading cylinder (1); Step 4: Use 3D printing technology to print the modeled mold (4); Step 5: The printed mold (4) is loaded into the cylindrical loading cylinder (1), and then the irregular complete curved surface of the bone cartilage can be subjected to compressive load loading.

8. The method for applying compressive load to the irregular intact surface of bone cartilage according to claim 5, characterized in that: When the customized mold (4) is made of titanium alloy, the specific operation steps are as follows: Step 1: Scan the osteochondral model using CT scanning; Step 2: Use modeling software to model the osteochondral data obtained from CT scanning, and obtain a mold surface that matches the cartilage surface through model conversion; Step 3: Process the mold surface to obtain processing information of each layer of the mold. The circumferential size of the mold is consistent with the size of the cylindrical loading cylinder (1), and the height of the mold is 1 / 4 of the height of the cylindrical loading cylinder (1); Step 4: Lay titanium powder on the forming workbench and perform laser sintering; Step 5: The sintered mold (4) is placed into the cylindrical loading cylinder (1), and then the irregular and complete curved surface of the bone cartilage can be subjected to compressive load loading.

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