CN112051118A

CN112051118A - 3D prints human bone joint biomechanics experimental system

Info

Publication number: CN112051118A
Application number: CN201910486202.4A
Authority: CN
Inventors: 刘展; 周佳盛; 罗皓天; 柳有好; 张远理
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2019-06-05
Filing date: 2019-06-05
Publication date: 2020-12-08

Abstract

The invention relates to a 3D printing human body bone joint biomechanical experiment system, which comprises: loading device, human bone joint 3D print model, pressure acquisition system, strain acquisition system. The loading device is a universal testing machine, and a pressure head of the universal testing machine generates vertical downward pressure on the 3D printing model. The 3D printing model is manufactured by 3D printing by utilizing a three-dimensional model established by a real human body CT/MRI scanning image. The pressure acquisition system is a film pressure test system, and a sensor of the pressure acquisition system is plugged into the joint to acquire pressure change data in the loading process. The strain acquisition system is a strain gauge, is adhered to the surface of the clean bone joint model and acquires the strain condition of the model in the loading process. The experiment system is used for carrying out relevant biomechanical research on a human bone joint system, and can be used for quickly and conveniently carrying out experiments while ensuring higher reliability.

Description

3D prints human bone joint biomechanics experimental system

Technical Field

The invention relates to a 3D printing human body bone joint biomechanical experiment system which is characterized in that a 3D printing technology is adopted to establish a bone joint model, and various obtained biomechanical properties of the model, including pressure, strain and other related data under different working conditions, are tested.

Background

The human bone joint generally consists of two bones and articular cartilage, a joint capsule, joint fluid and the like between the two bones. It is accompanied with various diseases in a human life, such as degenerative arthritis, synovitis, cervical spondylosis, lumbar disc herniation, etc., which are collectively called osteoarthropathy. Generally, various joint diseases of the patient can affect the normal life of the patient to a greater or lesser extent, and even can cause amputation and paralysis of the patient.

Along with the improvement of living standard, people pay more and more attention to joint health, and research on bone joint diseases is more and more. The most common method for the research of bone joint diseases at present is to research the bone joint system of human body by adopting theoretical knowledge of bone biomechanics and combining experiments and numerical simulation. However, in the current study of biomechanically relevant content of bone joints, there are certain factors that can seriously affect the study process. These factors include: the biomechanical experiments of the bone joints are usually performed in an animal experiment or human cadaver experiment mode, however, the animal experiment and the human cadaver experiment can consume a large amount of scientific research expenses and time of researchers, unnecessary psychological burdens of the researchers can be caused to a certain extent, and research work is seriously influenced. Secondly, if a living body testing mode is adopted, the method is limited by the current technical level, certain parameters cannot be measured on a living body, and the biomechanical property under abnormal working conditions cannot be researched. And thirdly, when the numerical simulation is carried out on the bone joint, the correctness of the obtained result cannot be known. However, if the numerical simulation is combined with the experiment for verification, the above-mentioned influencing factors (i) are present.

Disclosure of Invention

In view of the factors affecting the biomechanical studies of the bone joint discussed in the background section, the present invention aims to provide an experimental solution combining 3D printing technology and modern mechanical testing systems.

When solving a plurality of difficulties influencing the biomechanical research of the bone joint, the following technical problems to be solved exist: the method can establish a model with high similarity to the bone joints of a real human body. Secondly, when the model is prepared, the expenditure of the expenditure and the time can be reduced to the maximum extent by which mode. And thirdly, how the experimental system ensures convenient and fast data acquisition. Whether the established model can be stored for a long time or not and whether the experiment can be repeatedly carried out or not. How to ensure the accuracy of the experiment.

Aiming at the technical problems, the experiment provides the following experimental scheme which can solve various problems faced at present. The method comprises the following steps of establishing a bone joint three-dimensional digital model by taking CT (computed tomography) and Magnetic Resonance Imaging (MRI) scanning data of a real human bone joint as a basis, and manufacturing and generating a solid bone joint model by using the digital model through a 3D printing technology. CT scanning has a higher resolution for high density regions (bones), and therefore building a bone model using CT scan image data is more realistic. Since MRI has a higher resolution for low-density tissues (articular cartilage), it is also more realistic to scan bone joints with MRI and thus to model articular cartilage. ② 3D printing is a novel manufacturing technology, which has the advantages of high precision, high material utilization rate and the like, and can be used for manufacturing very complex structures conveniently. The technology is used for model making in the experimental system, and can meet the requirement of high similarity between the experimental model and the shape of the real human bone joint. Meanwhile, polylactic acid is used as a printing material of the skeleton, so that the model can be stored for a long time, and the experiment can be repeated, so that the verification experiment can be carried out, a large amount of experiment expenses and time can be saved, and the reliability of experiment data can be improved through repeated experiments. In addition, an experimental model is generated through 3D printing, a corpse experiment or an animal experiment with a complex flow can be omitted, the medical ethical problem does not exist or is few, scientific research personnel can conduct research conveniently, and the contradiction that finite element analysis cannot know the correctness of a calculation result is solved. And the related research shows that the elastic modulus of the articular cartilage is about 44.1MPa, so that the articular cartilage is similar to the actual human articular cartilage in the aspect of mechanical property as much as possible by selecting the silica gel as the material of the articular cartilage. In addition, in order to ensure that the model for the experiment is similar to the articular cartilage in the real human bone joint in shape, the articular cartilage is manufactured by adopting a mode of 3D printing an articular cartilage mould and then carrying out silica gel perfusion on the articular cartilage mould, so that the higher similarity of the cartilage model and the real articular cartilage on the appearance is ensured. And fourthly, the film pressure sensor is adopted as a pressure testing device, and the film pressure sensor has the characteristics of high precision, small thickness, relatively high toughness and the like, so that the film pressure sensor can be better qualified for pressure acquisition when testing structures with complicated shapes, such as bone joints, and the reliability of the measured pressure value is high. And fifthly, the strain gauge is adhered to the outer surface of the bone joint model by adopting the strain gauge, the strain test and the pressure test are carried out simultaneously, and the strain data and the pressure data can be conveniently compared, so that more reliable and useful information can be excavated.

Drawings

Fig. 1 is a schematic structural diagram of the present invention, and is also a front view of the experimental system.

Fig. 2 is an enlarged view of a right side view of a portion of the structure of fig. 1.

Fig. 3 is an enlarged view of a front view of a portion of the structure of fig. 1.

FIG. 4 is a schematic diagram of the pressure sensor of the experimental system of FIG. 1 disposed in the articular cartilage.

In the figure: the device comprises a universal testing machine 1, a universal testing machine 2, a pressure head of the universal testing machine 3, a bone model a, a bone model b 4, a temperature compensation device 5, a strain gauge 6, a pressure collector 7, a strain gauge 8, a cartilage model 9, a thin film pressure sensor 10, a thin film pressure sensor plug inlet and a thin film pressure sensor 11.

Detailed Description

The present invention will now be described by way of example using biomechanical tests of the temporomandibular joint of the human body.

As shown in fig. 1 to 4, a 3D printing human body bone joint biomechanics experiment system comprises: loading devices (corresponding to 1 and 2 in the figure); 3D printing models of human bone joints (corresponding to 3, 4 and 9 in the figure); a pressure acquisition system 9 (corresponding to 7, 10 and 11 in the figure); strain acquisition systems (corresponding to 5, 6 and 8 in the figure).

The experimental system is divided into five main steps: firstly, making a model; (II) preparing experimental equipment; (III) pretreating experimental materials; (IV) experiment; and (V) collecting and analyzing experimental data.

And (I) model making.

And (3) collecting one volunteer related to the content to be researched, and performing CT and MRI scanning on a maxillofacial temporomandibular joint region of the volunteer to obtain temporomandibular joint CT and MRI data.

Further, the collected CT/MRI file is converted in a computer into a digital imaging and communications in medicine (DICOM) format, which facilitates the three-dimensional modeling work.

Further, a three-dimensional temporomandibular joint bone file model is established in the computer by utilizing the DICOM format file of CT. Namely, a three-dimensional upper jaw model and a three-dimensional lower jaw model are established. Preferably, in order to simplify the experiment, the maxillary model is established by only keeping the maxillary bone, the temporal bone, the nasal bone, the zygomatic bone, part of occipital bone and other bones distributed on the outer side of the craniofacial bone. And the mandible model takes down the whole mandible.

Further, a three-dimensional model of the articular cartilage is established in a computer by utilizing a DICOM format file converted from a data file acquired by MRI scanning, and then a three-dimensional model of an articular cartilage mold is established, namely, a mold which is hollow inside and the hollow shape is the appearance of the articular cartilage is established in a Boolean operation mode and the like.

Further, the established three-dimensional digital upper and lower jaw model and the joint disc model are exported to a file format supported by 3D printing, and the digital model is printed into a solid model by using polylactic acid as a printing material by using a 3D printing technology.

(II) preparing experimental equipment.

Based on the acquisition of biomechanical relevant data of human joints, the invention needs to prepare the following equipment in the experimental process: the temperature compensation plate comprises a universal testing machine, a strain gauge and a temperature compensation plate (made of polylactic acid).

And (III) pretreating experimental materials.

And (3) polishing the surfaces of the upper and lower jaw models by using sand paper, and repeatedly cleaning the outer surfaces of the models by using acetone or industrial alcohol until the surfaces of the models are smooth and dustless.

Further, the strain gauge is adhered to the surface of the area to be studied of the upper and lower jaws with 502 glue, and the thumb of the user is compacted after adhering to ensure that no gap exists between the strain gauge and the model. The strain gage is then connected to the lead wire by soldering.

Further, a thin opening is cut on the side of the articular cartilage model by using a thin blade, and a thin film pressure sensor is plugged into the thin opening. Glue is suitably applied outside the thin opening to stabilize the membrane pressure sensor.

Furthermore, a temporomandibular joint system is placed below the universal tester pressure head, the placement of the joint system should be strictly performed according to physiological conditions (including normal physiological conditions and abnormal physiological conditions), and the upper end of the joint system is supported by a support to be flush with the universal tester pressure head.

Furthermore, the strain gauge is connected with a connecting wire of each part of the pressure sensor, wherein the strain gauge needs to be connected with a flat plate made of polylactic acid material for temperature compensation.

Further, the loading and unloading are repeated five times or so before the experiment is started, the loading pressure depends on different joints, and the loading of 100N is taken as an example in the embodiment. The influence of mechanical hysteresis on the experiment is reduced by repeatedly loading and unloading.

Furthermore, information such as the position of the articular cartilage in the joint gap, the contact area between the pressure head and the upper plane of the joint and the like is marked, and if a plurality of groups of models are tested, the names, the numbers, the codes and the like of the models in each group are marked so as to facilitate the distinguishing during data analysis.

And (IV) performing experiments.

And (3) pressing down the pressure head of the universal testing machine, loading the model from the pressure of 0N, stopping loading when the load is added to exceed a preset loading value of 10N-15N, and keeping about ten seconds until the loading load shown by the universal testing machine is unchanged. The final stable load value displayed by the universal tester is required to be within an acceptable range from the predetermined value. Preferably, for each predetermined load, the loading is repeated three times, and the average value is obtained to reduce experimental error.

And (V) collecting and analyzing experimental data.

And recording the strain and pressure values in each experiment, and calculating the mean value of the strain and pressure of the model under each preset load.

The present invention has been described more fully with reference to an exemplary embodiment, but it is not possible to cite all the possible experimental cases in this description, and therefore the above description is not meant to be a complete description of the invention. The invention can carry out relevant improvements according to the self requirements of experimenters, such as changing the joint area, changing the position of the film pressure sensor, selecting high load and the like. Therefore, any experimental scheme based on the idea of the invention and without innovative improvement is within the protection scope of the patent of the invention.

Claims

1. A3D printing human body bone joint biomechanical experiment system comprises: (1) a loading device; (2) 3D printing a model of a human bone joint; (3) a pressure acquisition system; (4) strain acquisition system, its characterized in that: a joint system model is established by using a 3D printing technology, the model is loaded by using a loading device (1), and various data obtained in the experimental process are collected by using a pressure acquisition system (3) and a strain acquisition system (4).

2. The (1) loading device according to claim 1, wherein a universal tester is used as the loading means, and a universal tester indenter is brought into contact with and applies downward pressure to the upper surface of the model.

3. The (2) human bone joint 3D printing model according to claim 1, wherein: the model is divided into two major parts, namely (5) a bone model and (6) a cartilage model.

4. The (5) skeleton model in the (2) human body bone joint 3D printing model according to the claim 1 and 3, characterized in that the model is made by building a digital three-dimensional model in a computer by medical image data acquired by CT scanning and then by 3D printing with polylactic acid as material.

5. The cartilage model (6) in the 3D printing model of human body bone joint according to the claim 1 and 3, characterized in that the model is made by building a digital three-dimensional model in a computer from medical image data obtained by Magnetic Resonance Imaging (MRI) scanning, then making a perfusion mold of the model through 3D printing, and finally perfusing with silica gel.

6. The (3) pressure acquisition system of claim 1, wherein: a thin opening is cut in the area to be studied and the membrane pressure sensor is inserted into the thin opening.

7. Strain acquisition system according to claim 1, characterised in that strain gauges are used as the instruments for strain measurement.

8. The strain acquisition system according to claims 1 and 7, characterized in that: the strain gauge attached strain gage was glued 502 to the outer surface of the bone model after cleaning with acetone.