Minimally invasive construction method of pig bone load-bearing and non-load-bearing region cartilage injury animal model

Abstract

The invention relates to the technical field of medicine, in particular to a minimally invasive construction method of a pig bone load-bearing and non-load-bearing area cartilage injury animal model, which comprises the following steps of: performing modeling based on pig CT (Computed Tomography) data; setting boundary conditions and applying a load; determining a stress area and a non-stress area according to a finite element analysis result; minimally-invasively exposing the medial condyle of the femur and performing osteochondral injury modeling; and noninvasively exposing the thighbone tackle cartilage and carrying out osteochondral injury modeling. According to the method, the stress area and the non-stress area of the pig knee joint are accurately defined through the finite element analysis technology. A minimally invasive surgery approach is creatively developed, full exposure of cartilages in different stress areas of the knee joint is achieved, and an important tool is provided for deep repair and reconstruction of cartilage injuries.

Description

Technical Field

[0001] The invention relates to the field of medical technology, and in particular to a minimally invasive method for constructing an animal model of cartilage injury in weight-bearing and non-weight-bearing areas of pig bones. Background Art

[0002] Osteochondral injury is a common disease in orthopedics, often affecting large joints such as the ankle, knee, and elbow. Since cartilage is a non-regenerative tissue, its treatment after injury has always been a difficult problem in the field of orthopedics. Existing methods have indeed achieved significant therapeutic effects in improving symptoms, but there are still many limitations in long-term effects and donor sources. Therefore, constructing a reliable animal model of cartilage injury to explore new treatment strategies is an important part of current cartilage repair and reconstruction.

[0003] At present, the construction of animal cartilage injury models mainly imitates the steps of total knee replacement surgery, but this method has problems such as large trauma, long recovery time, and high infection rate. In addition, the existing modeling methods often ignore the impact of different force differences at different injury sites on cartilage repair. Summary of the invention

[0004] The purpose of the present invention is to provide a minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing areas of pig bones, aiming to solve the problem of low safety of existing modeling methods and provide a reliable animal model for in-depth research on the influence of mechanical factors on cartilage repair.

[0005] To achieve the above object, the present invention provides a minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing regions of a pig bone, comprising the following steps:

[0006] Modeling based on pig CT data;

[0007] Set boundary conditions and apply loads;

[0008] Determine the stress-bearing area and non-stress-bearing area through finite element analysis results;

[0009] Minimally invasive exposure of the medial femoral condyle and osteochondral injury modeling;

[0010] The femoral trochlear cartilage was non-invasively exposed and osteochondral injury modeling was performed.

[0011] Among them, in "Modeling based on pig CT data", the following steps are included:

[0012] Obtain CT scan data of pig hind limbs;

[0013] The CT scan data was imported into the software for modeling.

[0014] Among them, in "Setting boundary conditions and applying loads", the load is 245N.

[0015] Among them, in “determining the stress-bearing area and the non-stress-bearing area through finite element analysis results”, the stress-bearing area is located at the medial condyle of the femur, with an average of 94.05 MPa, and the non-stress-bearing area is located at the medial trochlea of ​​the femur, with an average of 0.11 MPa.

[0016] Among them, in the "minimally invasive exposure of the medial femoral condyle and osteochondral injury modeling", it includes: exploring the surgical approach and constructing osteochondral injury on pig corpses.

[0017] The minimally invasive construction method of the pig bone weight-bearing and non-weight-bearing area cartilage injury animal model of the present invention comprises the following steps: modeling based on pig CT data; setting boundary conditions and applying loads; determining the force-bearing area and the non-force-bearing area through finite element analysis results; minimally invasively exposing the medial femoral condyle and modeling osteochondral injury; non-invasively exposing the femoral trochlear cartilage and modeling osteochondral injury. The present invention uses finite element analysis technology to deeply study the force conditions of the pig knee joint and accurately define the force-bearing area and non-force-bearing area of ​​the pig knee joint. Modeling in the same force-bearing area can compare the effects of different treatment methods on cartilage repair; while modeling in different force-bearing areas can explore the influence of mechanical factors on the same treatment method. In addition, the present invention innovatively develops a minimally invasive surgical approach, realizes the full cartilage exposure of the force-bearing area and the non-force-bearing area, effectively reduces the infection risk and surgical failure rate caused by surgical trauma, thereby improving the safety of existing animal experimental modeling methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is the result of finite element analysis.

[0020] Figure 2 A skin incision is made with the knee joint in natural flexion to expose the subcutaneous tissue.

[0021] Figure 3 The subcutaneous fascia is cut layer by layer to expose the joint capsule.

[0022] Figure 4 The joint capsule is cut to expose the articular surface of the medial femoral condyle.

[0023] Figure 5 The knee joint is straightened, a Hoffman retractor is inserted, and the trochlear articular surface is exposed.

[0024] Figure 6 and Figure 7 This is a postoperative specimen.

[0025] Figure 8 It is a flow chart of the minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing areas of a pig bone provided by the present invention. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0027] See also Figures 1 to 8 The present invention provides a minimally invasive method for constructing a pig bone weight-bearing and non-weight-bearing area cartilage injury animal model, comprising the following steps:

[0028] S1 was modeled based on pig CT data;

[0029] Obtain CT scan data of pig hind limbs; import the CT scan data into software for modeling.

[0030] Specifically, the CT scan data was imported into the medical 3D reconstruction software Mimics Research 19.0, and the femur, tibia, and patella were segmented and reconstructed by adjusting the threshold, region growth, segmentation mask, editing mask and other tools to establish the geometric model of the knee joint and output it as an STL format file. Then it was imported into the reverse engineering software Geomagic wrap 2017, and the model was denoised and smoothed. According to the geometric shape of each joint surface, the cartilage boundary was divided on each bone surface, and the cartilage was generated with a uniform offset of 0.2mm. Finally, the surface patches of each model were constructed, and the high-precision surfaces were fitted and output in Iges format. Then it was imported into the 3D design and modeling software NX12.0, and the various parts were assembled in space. The positions were placed according to the knee joint morphology of the miniature pig when walking. The 3D coordinate system was established with the femoral head as the center and the medial, mesial, and anterior sides of the knee joint as the XYZ axes. Finally, the data format was exported in Parasolid (X_T). The above model was imported into the finite element analysis software Abaqus6.14. For the nonlinear analysis of knee joint height discontinuity, the modified quadratic tetrahedron C3D10M unit was used for meshing to obtain better results. The specific unit and node numbers and material properties are shown below (Table 1, Table 2).

[0031] S2 sets boundary conditions and applies loads;

[0032] The load is 245N.

[0033] Specifically, the focus is on the stress distribution between the patellar joint and the knee joint, so the distal tibia is constrained: the degree of freedom is 0, the center of the femur is set as the reference point, the reference point is coupled with the femoral head, and a vertical downward concentrated force of 245N (approximately equal to the weight of the piglet 50 kg) is applied at the reference point.

[0034] S3 determines the stress-bearing area and the non-stress-bearing area through the finite element analysis results;

[0035] The stress-bearing area is located at the medial femoral condyle, with an average of 94.05 MPa, and the non-stress-bearing area is located at the medial femoral trochlea, with an average of 0.11 MPa.

[0036] Specifically, the maximum stress area of ​​the femur is in the medial femoral condyle, with an average of 94.05 MPa, and this area is defined as the stress-bearing area. The minimum stress area is located in the medial femoral trochlea, with an average of 0.11 MPa, and this area is defined as the non-stress-bearing area. This area is selected as the non-weight-bearing area modeling position ( Figure 1 ). The stress-bearing area and the non-stress-bearing area were selected as the target area for exposure and modeling.

[0037] S4 minimally invasively exposed the medial femoral condyle and performed osteochondral injury modeling;

[0038] The surgical approach and the construction of osteochondral lesions were explored in porcine cadavers.

[0039] Specifically, minimally invasive exposure of the medial femoral condyle and osteochondral injury modeling: exploration of surgical approach and construction of osteochondral injury were performed on pig cadavers. The pig cadavers were placed in a supine position with both knee joints in a natural flexion state. The inferior pole of the patella and the medial femoral condyle were touched, and a surgical incision of about 2 cm long was made from the inferior pole of the patella to the midpoint of the medial femoral condyle ( Figure 2 ), cut the skin and fascia layer by layer to expose the joint capsule ( Figure 3 ), cut the joint capsule along the direction of the skin incision, and pull the soft tissue to both sides to clearly expose the articular surface of the medial femoral condyle ( Figure 4 ). A Kirschner wire was inserted into the center of the modeling position for center positioning, and a matching electric twist drill was inserted along the Kirschner wire to create a bone cartilage defect. The depth and diameter were determined according to specific experiments.

[0040] S5 Non-invasively exposed the femoral trochlear cartilage and performed osteochondral injury modeling.

[0041] Specifically, non-invasive exposure of femoral trochlear cartilage and osteochondral injury modeling: straighten the knee joint, the surgical incision is moved upward to the inner side of the femoral trochlear as the knee joint is straightened, and a Hoffman retractor is inserted from the incision to the outer wall of the femoral trochlear, and the outer wall of the incision skin together with the subcutaneous fascia tissue is pulled to the outer side of the trochlear, completely exposing the inner and outer sides of the entire trochlear ( Figure 5 ). The osteochondral defect was created on the femoral trochlea in the same way as the medial femoral condyle.

[0042] Table 1: Elements and nodes

[0043] unit node Femur 117671 147880 Tibia 73449 93561 patella 7396 12023 Cartilage 37279 73059 Meniscus 9278 15882

[0044] Table 2: Material properties

[0045]

[0046]

[0047] Figure 6 The black arrow in the middle indicates the lateral surface of the joint capsule and the suture line in the surgical area, indicating that there is no obvious inflammatory hyperplasia around the surgical area.

[0048] Figure 7 The middle shows the joint capsule being incised from the contralateral side of the surgery. The black arrow indicates the medial side of the joint capsule in the surgical area, and the black triangle indicates the repaired cartilage tissue, indicating that minimally invasive modeling is conducive to the rapid healing of the joint capsule, significantly reducing inflammatory exudation and iatrogenic cartilage degeneration in the joint cavity, and improving the cartilage repair effect of the intervention measures.

[0049] The minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing regions of pig bones provided by the present invention has the following beneficial effects:

[0050] 1. The minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing areas of pig bones provided by the present invention improves the accuracy and safety of surgery:

[0051] Finite element analysis technology was used to accurately define the stress-bearing and non-stress-bearing areas of the pig knee joint, allowing the modeling process to be targeted at specific areas, avoiding the blindness of traditional modeling methods. The use of minimally invasive surgical approaches significantly reduced surgical trauma, reduced infection risks and surgical failure rates, and improved overall surgical safety and success rates.

[0052] 2. The minimally invasive method for constructing the animal model of cartilage injury in the weight-bearing and non-weight-bearing areas of pig bones provided by the present invention provides a new perspective and tool for the study of cartilage injury:

[0053] This method can construct an animal model that is consistent with the actual situation of human cartilage injury and is easy to observe and study. By modeling in the same stress zone, the effects of different treatments on cartilage repair can be compared, providing the possibility of exploring new treatment strategies. Modeling in different stress zones can explore the impact of mechanical factors on the same treatment method, providing an important tool for in-depth research on the impact of mechanical factors on cartilage repair.

[0054] 3. The minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing areas of pig bones provided by the present invention has promoted a breakthrough in the field of orthopedic research:

[0055] The proposal and application of this method not only solves the problems of large trauma, long recovery time, and high infection rate in existing modeling technologies, but also provides new ideas and methods for the research of cartilage injury repair and reconstruction. Through the continuous promotion and improvement of this method, it is expected to bring more innovative results and clinical application value to the field of orthopedics.

[0056] The above disclosure is only a preferred embodiment of the minimally invasive construction method of the animal model of cartilage injury in the weight-bearing and non-weight-bearing areas of the pig bone of the present invention. Of course, this cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention are still within the scope of the invention.

Claims

1. A minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing regions of a pig bone, characterized by: The following steps are involved: Modeling based on pig CT data; Set boundary conditions and apply loads; Determine the stress-bearing area and non-stress-bearing area through finite element analysis results; Minimally invasive exposure of the medial femoral condyle and osteochondral injury modeling; The femoral trochlear cartilage was non-invasively exposed and osteochondral injury modeling was performed.

2. The minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing regions of a pig bone according to claim 1, characterized in that: In "Modeling based on pig CT data", the following steps are included: Obtain CT scan data of pig hind limbs; The CT scan data was imported into the software for modeling.

3. The minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing regions of a pig bone according to claim 1, characterized in that: In "Setting Boundary Conditions and Applying Loads", the load is stated to be 245N.

4. The minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing regions of a pig bone according to claim 1, characterized in that: In "Determining the stress-bearing area and non-stress-bearing area through finite element analysis results", the stress-bearing area is located at the medial femoral condyle, with an average of 94.05 MPa, and the non-stress-bearing area is located at the medial femoral trochlea, with an average of 0.11 MPa.

5. The minimally invasive method for constructing an animal model of cartilage injury in the weight-bearing and non-weight-bearing regions of a pig bone according to claim 1, characterized in that: In "Minimally invasive exposure of the medial femoral condyle and osteochondral injury modeling", it includes: exploring the surgical approach and constructing osteochondral injury on pig corpses.

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