Device and method for detecting confining creep-recovery performance of cartilage

Abstract

The invention relates to a device and a method for detecting cartilage confinement creep-recovery performance. The device comprises a uniaxial compression testing machine, a confinement base, a confinement device, a cartilage fixing seat, a confinement pressure rod and a non-contact three-dimensional deformation measuring device, the confining base is fixedly arranged on a lower disc of the uniaxial compression testing machine and is used for supporting the confining device and loading a solution at the same time, so that the cartilage is kept in a liquid environment; the confining device is fixedly arranged in the confining base, so that the cartilage to be experimented is in a confining state; the cartilage fixing seat is detachably and fixedly arranged at the bottom of the confining device, and the upper end of the cartilage fixing seat is used for bearing and fixing a cartilage sample; the confining pressure rod is fixed to an upper disc of the testing machine, the lower end of the confining pressure rod makes contact with the cartilage, the testing machine applies pressure to the confining pressure rod, and meanwhile the descending height of the confining pressure rod is obtained; the non-contact three-dimensional deformation measuring device is arranged on one side of the uniaxial compression testing machine and is used for observing the recovery process after cartilage creep. The mechanical environment of the cartilage in-vivo environment is simulated to the maximum extent.

Description

Technical Field

[0001] The invention belongs to the field of biomechanics and material detection, and specifically relates to a device and method for detecting the confined creep-recovery performance of cartilage. Background Art

[0002] Bone joints are subjected to various loads generated by their own weight and muscle contraction, and articular cartilage plays an important role in buffering and transmitting these loads. Among them, the creep-recovery performance of articular cartilage directly affects the stability of joints under long-term loads. By studying the creep-recovery performance, we can better understand how articular cartilage maintains normal physiological functions under different static / dynamic mechanical environments. In addition, many joint diseases, such as osteoarthritis, sports injuries, etc., will lead to changes in the creep-recovery performance of articular cartilage. Therefore, studying this performance will help develop more efficient diagnostic methods, thereby achieving effective control of disease progression and detection of treatment effects.

[0003] The general method for testing the creep properties of materials is to use compression / tensile tests. This kind of experiment often requires the specimen to have regular size and shape to meet the test standards and loading requirements. Therefore, this method is frequently used in metals or artificial materials that are easy to sample. However, for natural cartilage, due to the individual differences of organisms and the particularity of their own mechanical properties, it is basically impossible to meet the requirements of general compression / tensile tests. More importantly, for biomaterials, maintaining the liquid environment in which they are located can avoid denaturation during the experiment, so it is necessary to find a creep-recovery performance testing method that is sufficient to meet the above-mentioned mechanical properties of cartilage.

[0004] Therefore, when conducting in vitro confined creep-recovery performance testing on cartilage with complex mechanical properties, the error caused by the irregular shape of the cartilage should be avoided as much as possible. Specifically, a sample with a larger contact area should be used to conduct the experiment, and the confining conditions and liquid environment should be guaranteed. At the same time, the device needs to be able to observe the recovery performance of the confined cartilage immediately after the creep experiment, and in order to ensure the detection accuracy, the device needs to be able to achieve micro-newton and micron-level detection effects.

[0005] SUMMARY OF THE INVENTION

[0006] In view of the deficiencies of the prior art, the present invention proposes a device and method for detecting the confined creep-recovery performance of cartilage, which effectively improves the detection accuracy and stability.

[0007] One of the above objects of the present invention is achieved by the following technical solution:

[0008] A device for detecting the confined creep-recovery performance of cartilage, comprising a uniaxial compression testing machine, a confining base, a confining device, a cartilage fixing seat, a confining pressure rod, and a non-contact three-dimensional deformation measuring device;

[0009] The confinement base is fixedly mounted on the lower disc of the uniaxial compression testing machine, and is used to support the confinement device and load the solution at the same time, so that the cartilage is kept in a liquid environment to maintain biological activity;

[0010] The confinement device is fixedly placed in the confinement base, so that the cartilage to be tested is in a confined state and provides space for the experiment;

[0011] The cartilage fixing seat is detachably fixed to the bottom of the confinement device, and its upper end is used to carry and fix the cartilage sample;

[0012] The confining pressure rod is fixed to the upper disc of the testing machine, the confining pressure rod and the confining base are aligned vertically, the lower end of the confining pressure rod is in contact with the cartilage, the testing machine applies pressure to the confining pressure rod, and simultaneously obtains the descending height of the confining pressure rod, and the descending height of the confining pressure rod is consistent with the deformation amount of the cartilage;

[0013] The non-contact three-dimensional deformation measuring device is arranged on one side of the uniaxial compression testing machine and is used to observe the recovery process of cartilage after creep.

[0014] Moreover, the confinement base adopts a columnar structure with a flange at the lower end, and a support hole and a liquid storage hole are coaxially arranged above and below the center of the columnar part of the confinement base. The support hole adopts a rectangular hole, and the liquid storage hole adopts a circular hole. The side length of the support hole is greater than the diameter of the liquid storage hole, and the two constitute a space that can carry the confinement device; screw through holes are arranged on both sides of the support hole in the columnar part of the confinement base, and the screw through holes are vertically connected to the support hole; the lower end flange of the confinement base is connected to the lower disc of the uniaxial compression testing machine by screws.

[0015] Moreover, the confinement device adopts a three-section structure, consisting of an upper cylindrical section, a middle long square section and a lower cylindrical section; the side length of the middle long square section is greater than the diameter of the upper and lower cylindrical sections; the shape and size of the middle long square section are consistent with the shape and size of the support hole on the confinement base, and threaded holes are arranged on both sides of the middle long square section, and the two threaded holes correspond one by one to the two screw holes on the confinement base, and the diameter of the lower cylindrical section is smaller than the diameter of the liquid storage hole on the confinement base; a through hole is arranged at the center of the confinement device, and the through hole is composed of a main hole section and a bottom hole section arranged upper and lower; the middle long square section of the confinement device is inserted and positioned with the support hole of the confinement base, and a fixed connection is formed by the set screws connected to the two sides; the lower cylindrical section of the confinement device extends into the liquid storage hole of the confinement base.

[0016] Moreover, the cartilage fixing seat adopts a three-section structure, which is composed of an upper cylindrical section, a middle rod-shaped transition connecting section and a lower rectangular parallelepiped buckle section; the upper end surface of the upper cylindrical section is the bonding and fixing surface of the cartilage; the middle rod-shaped transition connecting section is freely assembled and matched with the bottom hole section of the confining device, and its length is consistent with the length of the bottom hole section; the long side dimension of the lower rectangular parallelepiped buckle section is smaller than the length of the bottom hole section and larger than the width of the bottom hole section. After passing through the bottom hole section of the confining device, the lower rectangular parallelepiped buckle section is rotated and clamped, so that the cartilage fixing seat forms a detachable connection with the confining device.

[0017] Moreover, a reflux hole is arranged on the side wall corresponding to the main hole section near the bottom hole section, and the distance between the lower edge of the reflux hole and the bottom of the main hole section should be greater than the upper end position of the cartilage after being placed in the main hole section.

[0018] Moreover, the confining pressure rod is a cylindrical rod with a flange at the upper end. The upper end flange of the confining pressure rod is connected to the upper disc of the uniaxial compression testing machine by screws, and the diameter of the cylindrical rod is consistent with the diameter of the main hole section of the confining device.

[0019] The second objective of the present invention is achieved by the following technical solutions:

[0020] A method for detecting the confined creep performance and creep recovery performance of cartilage, the method is implemented by using the above-mentioned device for detecting the confined creep-recovery performance of cartilage, and comprises the following steps:

[0021] Step 1: Process the cartilage sample containing the underlying bone, remove the cartilage calcification layer and the tissue below, and ensure that the cartilage can be easily flattened; then use a round-mouth punch to make the cartilage into a disc shape, and evenly apply ethyl cyanoacrylate adhesive on the lower surface of the cartilage and the upper surface of the cartilage fixation seat to fix them together; place the two at the bottom of the confinement device, and rotate the cartilage fixation seat to fix it in the confinement device;

[0022] Step 2: Place the enclosure in the enclosure base and fasten the enclosure to the enclosure base using screws on both sides;

[0023] Step 3, drip the solution required for the experiment into the confining vessel so that the liquid level is higher than the reflux hole;

[0024] Step 4: fix the confinement base to the lower disc of the testing machine, fix the confinement pressure rod to the upper disc of the testing machine, and move the confinement pressure rod to just contact the upper surface of the cartilage;

[0025] Step 5: Adjust the non-contact three-dimensional deformation measuring device so that it can clearly observe the cartilage deformation, reset the values ​​of the pressure sensor and displacement sensor of the testing machine, set appropriate pressure and time, and start the experiment; after the experiment, set the limiting pressure rod to be lifted immediately, and the non-contact three-dimensional deformation measuring device 1 will record the recovery process of the cartilage.

[0026] The advantages and positive effects of the present invention are:

[0027] 1. The present invention ensures the accuracy and stability of the test by using the downward pressure actuator and the pressure / displacement sensor mechanism which are arranged relatively up and down on the testing machine. Specifically, the downward pressure actuator under closed-loop control applies a highly stable constant load to the confining pressure rod; at the same time, the downward pressure actuator includes a high-precision displacement sensor, which can accurately detect the height index of the confining pressure rod falling due to cartilage deformation.

[0028] 2. This device and detection method can keep the sample in a liquid environment for a long time, measure and record its creep and recovery performance in real time, and simulate the mechanical environment of cartilage in the body to the maximum extent. Compared with most conventional creep tests, it effectively avoids the errors caused by the timeliness and individual differences of biological samples, and promotes the development of the field of biomaterial mechanical properties testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the device for detecting the confined creep-recovery performance of cartilage of the present invention (without a computer);

[0030] Figure 2 yes Figure 1 The front view of the non-contact three-dimensional deformation measuring device (including the computer) is removed;

[0031] Figure 3 yes Figure 2 Front view without the uniaxial compression testing machine and computer;

[0032] Figure 4 is a stereoscopic diagram of the confinement device of the present invention;

[0033] Figure 5 It is a stereoscopic diagram of the cartilage fixation seat of the present invention. DETAILED DESCRIPTION

[0034] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0035] A device and method for detecting the confined creep-recovery performance of cartilage, see Figure 1-5The invention point is: it mainly includes a non-contact three-dimensional deformation measuring device 1, a uniaxial compression testing machine 2, a confining pressure rod 4, a confining base 5, a computer 7, a fastening screw 8, a confining device 9, a cartilage fixing seat 11, etc., wherein the upper disc 3 of the uniaxial compression testing machine is a power disc that can move up and down by applying downward pressure, and the lower disc 6 of the uniaxial compression testing machine is a fixed disc, and the upper pressure plate and the lower pressure plate are coaxially arranged up and down.

[0036] The uniaxial compression testing machine, the confining pressure rod, the confining base, the computer, the fastening screws, the confining device, and the cartilage fixing seat constitute a device for applying pressure to deform the cartilage.

[0037] The non-contact three-dimensional deformation measurement device is set outside the device that applies pressure and deformation, and is used to obtain information about the compression deformation process of the cartilage. Specifically, the front image of the cartilage recovery process is collected at a fixed frequency, and then the strain is calculated using software such as Image-J to obtain its strain-time curve.

[0038] The confinement base adopts a columnar structure with a flange at the lower end. The columnar shape is preferably a square column. A support hole and a liquid storage hole are coaxially arranged at the upper and lower centers of the columnar part of the confinement base. The support hole is a rectangular hole, and the liquid storage hole is a circular hole. The side length of the support hole is greater than the diameter of the liquid storage hole. The space formed by the two can carry the confinement device. Screw holes are arranged on both sides of the support hole in the columnar part of the confinement base. The screw holes are vertically connected to the support holes and are used to install fastening screws to fix the confinement device installed therein. The lower end flange of the confinement base is connected to the lower disc of the uniaxial compression testing machine by screws to fix the confinement base to the lower disc of the uniaxial compression testing machine.

[0039] The confinement device adopts a three-section structure, consisting of an upper cylindrical section 9.1, a middle long square section 9.2 and a lower cylindrical section 9.3. The three sections are coaxially arranged and can be integrally formed by 3D printing. The side length of the middle long square section is greater than the diameter of the upper and lower cylindrical sections. The shape and size of the middle long square section are consistent with the shape and size of the support hole on the confinement base, and threaded holes 9.4 are relatively arranged on both sides of the middle long square section, and the two threaded holes correspond one by one to the two screw holes on the confinement base. The diameter of the lower cylindrical section is smaller than the diameter of the liquid storage hole on the confinement base. In the present invention, the diameter of the liquid storage hole is 14.5 mm, and the outer diameter of the lower cylindrical section is 11.5 mm.

[0040] A through hole is provided at the center of the confinement device, and the through hole is composed of a main hole section and a bottom hole section arranged up and down. The main hole section adopts a round hole, and the bottom hole section adopts a waist-shaped hole, and the cross-sectional size of the bottom hole section is smaller than the cross-sectional size of the main hole section. The function of the bottom hole section is to realize the installation of the cartilage fixing seat. Further, a reflux hole 9.5 is provided on the side wall corresponding to the main hole section near the bottom hole section, and the distance between the lower edge of the reflux hole and the bottom of the main hole section should be greater than the upper end position of the cartilage after being placed in the main hole section. In the present invention, the height of the cartilage is generally 2-3mm, and the reflux hole is preferably a rectangular hole with a length of 2mm and a width of 1mm, and the distance between the lower edge of the reflux hole and the bottom of the main hole section is 4mm. The purpose of using the reflux hole is: after testing the creep performance of the confinement, after the testing machine lifts the confinement pressure rod, part of the liquid in the liquid storage cavity enters the main hole section from the reflux hole, so as to achieve the purpose of cartilage recovery in a liquid-filled environment.

[0041] The cartilage fixing seat adopts a three-section structure, which is composed of an upper cylindrical section 11.1, a middle rod-shaped transition connecting section 11.2 and a lower rectangular parallelepiped buckle section 11.3. The upper end surface of the upper cylindrical section is the bonding and fixing surface of the cartilage, which is used to bond with the lower end of the hose to be tested through an adhesive to fix the cartilage to the upper end of the cartilage fixing seat. The middle rod-shaped transition connecting section is used to freely fit with the bottom hole section of the confinement device, and its length is consistent with the length of the bottom hole section. The long side dimension of the lower rectangular parallelepiped buckle section is smaller than the length of the bottom hole section, but larger than the width of the bottom hole section, so that the lower rectangular parallelepiped buckle section can smoothly pass through the bottom hole section from top to bottom. After passing through the bottom hole section, it can be rotated at a certain angle to clamp the cartilage fixing seat at the bottom of the confinement device. At this time, the cartilage fixing seat is completely placed in the main hole section of the confinement device. The use of this cartilage fixing seat has the advantage of convenient installation and disassembly.

[0042] The confining pressure rod 4 is a cylindrical rod with a flange at the upper end, and the upper end flange of the confining pressure rod is connected to the upper disc of the uniaxial compression testing machine by screws. The diameter of the cylindrical rod is consistent with the diameter of the main hole section of the confining device, so that the cylindrical rod can be inserted into the main hole section from top to bottom in a clearance fit manner. When the lower end of the cylindrical rod contacts the upper end of the cartilage to be tested, the testing machine applies pressure to the confining pressure rod, and at the same time obtains the descending height of the confining pressure rod, which is the deformation amount of the cartilage. The magnitude of the applied pressure of the uniaxial compression testing machine is obtained by the pressure sensor on the uniaxial compression testing machine. In the present invention, the upper pressure limit of the pressure sensor of the uniaxial compression testing machine 2 is 120N, the force sensing accuracy is 0.0001N, and the displacement sensing accuracy is 0.0001mm.

[0043] In the above structure, the confinement base and the confinement device are made of transparent materials, and the processing methods of the two include but are not limited to additive manufacturing or subtractive molding, and the processing materials include but are not limited to resin, engineering plastics or polymer materials. The confinement pressure rod and cartilage fixing seat are made of high-hardness metal materials.

[0044] A method for detecting the confined creep performance and creep recovery performance of cartilage, the method is implemented by using the above-mentioned device for detecting the confined creep-recovery performance of cartilage, and comprises the following steps:

[0045] Step 1: Process the cartilage sample containing the lower bone, remove the cartilage calcification layer and the tissue below, and ensure that the cartilage can be easily flattened; then use a round-mouth punch to make the cartilage into a disc shape. In this embodiment, a disc shape with a diameter of 7.5 mm is used, and the lower surface of the cartilage 10 and the upper surface of the cartilage fixing seat 11 are evenly coated with ethyl cyanoacrylate adhesive to fix them together; place the two at the bottom of the confinement device 9, and rotate the cartilage fixing seat to fix it in the confinement device 9;

[0046] Step 2: Place the confinement device 9 in the confinement base 5, and fasten the confinement device 9 to the confinement base 5 using screws 8 on both sides;

[0047] Step 3, drip the solution required for the experiment into the confinement vessel 9 so that the liquid level is higher than the reflux hole;

[0048] Step 4, fix the confining base 5 to the lower disc 6 of the testing machine, fix the confining pressure rod 4 to the upper disc 3 of the testing machine, and move the confining pressure rod 4 to make it just contact the upper surface of the cartilage 10;

[0049] Step 5: Adjust the non-contact three-dimensional deformation measuring device 1 so that it can clearly observe the cartilage deformation, reset the values ​​of the pressure sensor and displacement sensor of the testing machine, set appropriate pressure and time, and start the experiment; after the experiment, set the limiting pressure rod 4 to be lifted immediately, and the non-contact three-dimensional deformation measuring device 1 will record the recovery process of the cartilage.

[0050] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A device for detecting the confined creep-recovery performance of cartilage, characterized in that: It includes a uniaxial compression testing machine, a confining base, a confining device, a cartilage fixing seat, a confining pressure rod, and a non-contact three-dimensional deformation measuring device; The confinement base is fixedly mounted on the lower disc of the uniaxial compression testing machine, and is used to support the confinement device and load the solution at the same time, so that the cartilage is kept in a liquid environment; The confinement device is fixedly placed in the confinement base, so that the cartilage to be tested is in a confined state; The cartilage fixing seat is detachably fixed to the bottom of the confinement device, and its upper end is used to carry and fix the cartilage sample; The confining pressure rod is fixed to the upper disc of the testing machine, the confining pressure rod and the confining base are aligned vertically, the lower end of the confining pressure rod is in contact with the cartilage, the testing machine applies pressure to the confining pressure rod, and simultaneously obtains the descending height of the confining pressure rod, and the descending height of the confining pressure rod is consistent with the deformation amount of the cartilage; The non-contact three-dimensional deformation measuring device is arranged on one side of the uniaxial compression testing machine and is used to observe the recovery process of cartilage after creep.

2. The device for detecting the confined creep-recovery performance of cartilage according to claim 1, characterized in that: The confinement base adopts a columnar structure with a flange at the lower end, and a support hole and a liquid storage hole are coaxially arranged at the upper and lower centers of the columnar part of the confinement base. The support hole is a rectangular hole, and the liquid storage hole is a circular hole. The side length of the support hole is greater than the diameter of the liquid storage hole, and the two constitute a space that can carry the confinement device; screw through holes are arranged on both sides of the support hole in the columnar part of the confinement base, and the screw through holes are vertically connected to the support hole; the lower end flange of the confinement base is connected to the lower disc of the uniaxial compression testing machine by screws.

3. The device for detecting the confined creep-recovery performance of cartilage according to claim 2, characterized in that: The confinement device adopts a three-section structure, consisting of an upper cylindrical section, a middle long square section and a lower cylindrical section; the side length of the middle long square section is greater than the diameter of the upper and lower cylindrical sections; the shape and size of the middle long square section are consistent with the shape and size of the support hole on the confinement base, and threaded holes are arranged on both sides of the middle long square section, and the two threaded holes correspond to the two screw holes on the confinement base one by one, and the diameter of the lower cylindrical section is smaller than the diameter of the liquid storage hole on the confinement base; a through hole is arranged at the center of the confinement device, and the through hole is composed of a main hole section and a bottom hole section arranged upper and lower; the middle long square section of the confinement device is inserted and positioned with the support hole of the confinement base, and a fixed connection is formed by the set screws connected to the two sides; the lower cylindrical section of the confinement device extends into the liquid storage hole of the confinement base.

4. The device for detecting the confined creep-recovery performance of cartilage according to claim 3, characterized in that: The cartilage fixing seat adopts a three-section structure, which is composed of an upper cylindrical section, a middle rod-shaped transition connecting section and a lower rectangular parallelepiped buckle section; the upper end surface of the upper cylindrical section is the bonding and fixing surface of the cartilage; the middle rod-shaped transition connecting section is freely assembled and matched with the bottom hole section of the confining device, and its length is consistent with the length of the bottom hole section; the long side dimension of the lower rectangular parallelepiped buckle section is smaller than the length of the bottom hole section and larger than the width of the bottom hole section. After passing through the bottom hole section of the confining device, the lower rectangular parallelepiped buckle section is rotated and clamped, so that the cartilage fixing seat forms a detachable connection with the confining device.

5. The device for detecting the confined creep-recovery performance of cartilage according to claim 3, characterized in that: A reflux hole is arranged on the side wall corresponding to the main hole section near the bottom hole section, and the distance between the lower edge of the reflux hole and the bottom of the main hole section is greater than the upper end position of the cartilage after being placed in the main hole section.

6. The device for detecting the confined creep-recovery performance of cartilage according to claim 1, characterized in that: The confining pressure rod is a cylindrical rod with a flange at the upper end. The upper end flange of the confining pressure rod is connected to the upper disc of the uniaxial compression testing machine by screws. The diameter of the cylindrical rod is consistent with the diameter of the main hole section of the confining device.

7. A method for detecting the confined creep performance and creep recovery performance of cartilage, the method being implemented by the device for detecting the confined creep-recovery performance of cartilage according to any one of claims 1 to 6, comprising the following steps: Step 1: Process the cartilage sample containing the underlying bone, remove the cartilage calcification layer and the tissue below, and ensure that the cartilage can be easily flattened; then use a round-mouth punch to make the cartilage into a disc shape, and evenly apply ethyl cyanoacrylate adhesive on the lower surface of the cartilage and the upper surface of the cartilage fixation seat to fix them together; place the two at the bottom of the confinement device, and rotate the cartilage fixation seat to fix it in the confinement device; Step 2: Place the enclosure in the enclosure base and fasten the enclosure to the enclosure base using screws on both sides; Step 3, drip the solution required for the experiment into the confining vessel so that the liquid level is higher than the reflux hole; Step 4: fix the confinement base to the lower disc of the testing machine, fix the confinement pressure rod to the upper disc of the testing machine, and move the confinement pressure rod to just contact the upper surface of the cartilage; Step 5: Adjust the non-contact three-dimensional deformation measuring device so that it can clearly observe the cartilage deformation, reset the values ​​of the pressure sensor and displacement sensor of the testing machine, set appropriate pressure and time, and start the experiment; after the experiment, set the limiting pressure rod to be lifted immediately, and the non-contact three-dimensional deformation measuring device 1 will record the recovery process of the cartilage.

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