Scoliosis biomechanical testing method

Abstract

The invention provides a scoliosis biomechanical testing method, and belongs to the technical field of scoliosis testing, and the scoliosis biomechanical testing method comprises sheep spine bending and nail bar implantation. Sheep spine bending comprises the steps of cutting a sheep spine, fixing an end cover, connecting a translation tool and a clamping tool, driving a middle vertebral body of the sheep spine to move so as to bend the sheep spine, releasing an intervertebral disc with the maximum bending degree, filling denture powder for fixing, and turning segments above and below a lateral convex part of the sheep spine back to be vertical; nail and bar implanting comprises bone nail hole drilling, bone nail implanting and bar implanting. The sheep spine is selected to simulate the human spine, high similarity is achieved, human scoliosis is completely simulated through specific steps of bending and nail bar implantation, and biomechanical testing on human scoliosis is facilitated.

Description

Technical Field

[0001] This invention relates to the field of scoliosis testing technology, and more specifically to a biomechanical testing method for scoliosis. Background Technology

[0002] Scoliosis is a disease characterized by three-dimensional spinal deformities, primarily including coronal scoliosis, sagittal imbalance, and horizontal rotation. In recent years, its incidence has been on the rise, with a high proportion of cases occurring in adolescents. Currently, patients with severe deformities often require surgical correction, such as posterior fusion or hemivertebrae resection. Static or dynamic studies on cadaveric specimens have long been considered the "gold standard" for biomechanical research of various surgical procedures. However, due to limitations imposed by traditional concepts and preservation conditions, obtaining fresh frozen cadaveric specimens is extremely difficult, and obtaining pediatric spinal specimens for scoliosis modeling is even more challenging. Current technologies employ three-dimensional modeling and 3D printing to create human spinal models for experiments. However, 3D printing cannot simulate the soft tissues of the human spine, such as intervertebral discs, ligaments, and joint capsules, resulting in differences in stability and function between the 3D-printed model and the human spine, leading to unsatisfactory simulation results.

[0003] Furthermore, existing technologies, such as finite element method (FEM), offer advantages like high repeatability and ease of operation, making them an ideal method for measuring stress-strain. FEM allows for comparison of stress-strain differences between different surgical procedures within the same spinal model, and can simulate the stress trends at any location within the spinal structure to a certain extent. However, human tissues are extremely complex, and current FEM methods cannot accurately reflect the diversity of human tissues.

[0004] Previous studies have shown that sheep spines can serve as animal models for biomechanical studies of the human spine. Animal spine specimens share good similarities with human tissue structure and are readily available. By applying different mechanical loads, the movement trajectory of the human spine can be simulated, thereby allowing analysis of the stress-strain characteristics of specific nodes.

[0005] Therefore, this invention provides a method for creating a scoliosis model based on the sheep spine to study the biomechanical properties of different orthopedic surgical procedures. Summary of the Invention

[0006] The purpose of this invention is to provide a biomechanical testing method for scoliosis.

[0007] To solve the above-mentioned technical problems, the objective of this invention is achieved as follows: A biomechanical testing method for scoliosis includes the following steps: S1. Spine bending in sheep; S2, implant the nail rod; Step S1 includes the following steps: ① Cutting the sheep spine, including several thoracic vertebrae and several lumbar vertebrae connected to the thoracic vertebrae, while preserving the transverse processes, spinous processes, ligaments and joint capsules of the sheep spine; ② The end caps are placed on the vertebrae at both ends of the sheep's spine for embedding, and dental plaster is filled between the vertebrae and the end caps for fixation; ③ Fix both ends of the sheep spine to two translation fixtures respectively, and use clamping fixtures to clamp the middle of the sheep spine; the two translation fixtures can drive the ends of the sheep spine to move horizontally and longitudinally and rotate along the axis of the sheep spine; the clamping fixtures can translate horizontally, rotate along the longitudinal axis and rotate along the vertical axis. ④ Use a clamping device to cause the middle of the sheep's spine to protrude to one side or / and twist, thus bending and fixing the sheep's spine. Cut open the intervertebral disc with the greatest degree of lateral curvature of the sheep's spine to release it, and remove the excess intervertebral disc and scrape away the intervertebral discs that are adhered to the vertebral lamina. After the release is completed, use the clamping device to continue to cause the middle of the sheep's spine to protrude or / and twist until the Cobb angle meets the set requirements and then fix it. After fixation, use dental tray powder to fill the intervertebral space and use a film to cover it to prevent the dental tray powder from flowing out. ⑤ After the dental tray powder solidifies, use a clamping fixture to clamp and fix the vertebra above the scoliosis of the sheep's spine. The translation fixture at the top of the sheep's spine moves and / or rotates to move the sheep's spine, gradually bringing the segment above the scoliosis back to a vertical position. The process of turning it vertical is as follows: when the translation fixture moves and / or rotates the segment of the sheep's spine above the scoliosis to the maximum curvature of the sheep's spine, it is fixed. After fixing, the intervertebral disc with the greatest curvature is cut open to release it. After the release is completed, the translation fixture at the top of the sheep's spine continues to move and / or rotate, bringing the segment above the scoliosis back to a vertical position, and the Cobb angle meets the set requirements, and is then fixed. After fixing, dental tray powder is used to fill the intervertebral space, and a film is used to cover it to prevent the dental tray powder from flowing out. ⑥ After the dental tray powder solidifies, it helps the segment below the scoliosis of the sheep's spine return to a vertical position. The operation method is the same as that for the segment above the scoliosis of the sheep's spine. After the segments above and below the scoliosis of the sheep's spine have returned to a vertical position, the deformed spine model is completed. Step S2 includes the following steps: ① Pin tract detection: using a C-arm machine for detection; the C-arm machine partially surrounds the sheep's spine, with an X-ray emitting end at one end and an X-ray receiving end at the other end. The C-arm machine moves the X-ray emitting end and the X-ray receiving end to perform X-ray scanning on the sheep's spine to determine the position and direction of the pin tract. ② Drilling: Based on the results of the nail track detection, drill several bone nail screw holes in the sheep's spine; ③ Insert the screw: Screw the bone screw into the screw hole of the bone screw; ④ Mounting the rod: First, bend the malleable rod to match the curvature of the sheep's spine. Then, connect the bent rod to the bone screw. Adjust the bending state of the rod according to the sheep's spine until it perfectly matches the curvature of the sheep's spine, serving as a reference for the bending shape and length of the titanium rod. Process the titanium rod according to the bending state and length of the rod to match the sheep's spine. Then, connect the processed titanium rod to the bone screw to complete the assembly of the test model.

[0008] Based on the above scheme and as a preferred embodiment of the above scheme, step S1 further includes: after the dental tray powder solidifies, removing the covering film, and then disassembling the sheep spine and end caps that have completed the deformity simulation from the translation fixture and clamping fixture, and transferring them to the testing equipment.

[0009] Based on the above scheme and as a preferred embodiment of the above scheme, the bone screw includes a rod portion that is inserted into the bone screw hole and an insert portion connected to the end of the rod portion; the insert portion includes two support arms that hold the titanium rod and a screw plug that is threaded between the two support arms.

[0010] Based on the above scheme and as a preferred embodiment of the above scheme, the drilling step S2 includes: disassembling the X-ray transmitter and X-ray receiver on the C-arm machine, then installing the guide sleeve, and using the C-arm machine to fix the guide sleeve to ensure accurate drilling positioning.

[0011] Based on the above scheme and as a preferred embodiment of the above scheme, the surface of the mold rod is provided with a number of length marks evenly distributed along its length; the distance between two adjacent length marks is the unit length, and the required length of the titanium rod can be quickly determined by the number of the length marks.

[0012] The beneficial effects of this invention are: 1. This invention uses a sheep spine to simulate the human spine. The sheep spine shares a high degree of similarity with the human spine in terms of tissue structure and characteristics. Simulating the human spine for mechanical testing ensures more accurate test results and better performance. Sheep spines are inexpensive and readily available, reducing the difficulty and cost of testing.

[0013] 2. In simulating scoliosis in sheep, the present invention first bends the sheep's spine to its maximum extent, then removes the intervertebral disc with the greatest curvature, and fills the intervertebral disc gap with dental tray powder to keep it fixed and prevent the sheep's spine from returning to vertical, thus keeping the sheep's spine in a scoliosis state to simulate human scoliosis. The operation is simple; the dental tray powder can simulate the intervertebral disc, ensuring the reliability of the test results.

[0014] 3. Using X-ray scanning of the sheep's spine to determine the location and direction of the screw holes for the bone nails can prevent drilling through the sheep's spine and thus avoid test failure. At the same time, it can also improve the accuracy of the bone nail implantation position, making the model more realistic.

[0015] 4. In this invention, a malleable mold rod is fixed to the sheep's spine. Through multiple bending, the bending degree of the mold rod is made to completely match the bending state of the sheep's spine, which serves as a bending reference for the titanium rod. The titanium rod is then processed, which can ensure that the titanium rod is formed in one step, saving more time and effort. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the sheep spine and various tooling components of the present invention.

[0017] Figure 2 This is a schematic diagram of the structure of the sheep spine end cap of the present invention.

[0018] Figure 3 This is a schematic diagram of the nail rod structure of the present invention.

[0019] In the diagram: 1. End cap; 2. Translation fixture; 3. Clamping fixture; 4. C-arm machine; 5. Bone screw; 6. Titanium rod; 7. Plug. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] A biomechanical testing method for scoliosis includes the following steps: S1. Spine bending in sheep; S2, implant the nail rod.

[0022] Step S1 includes the following steps: ① The sheep spine is harvested, including several thoracic vertebrae and several lumbar vertebrae connected to the thoracic vertebrae. The transverse processes, spinous processes, ligaments, and joint capsules of the sheep spine are preserved to ensure that the spinal structure and intervertebral tissues are similar to those of the human body. In this embodiment, 13 thoracic vertebrae and 6 lumbar vertebrae of the sheep spine are harvested, totaling 19 segments. Seventeen vertebrae in the middle segments are harvested, preserving the transverse processes, spinous processes, ligaments, joint capsules, and other features, while ensuring that the surface of the vertebral body is free of defects such as knife marks and holes.

[0023] ② The end cap 1 is fitted over the vertebral bodies at both ends of the sheep's spine for embedding. Dental adhesive powder is used to fill the gap between the vertebral bodies and the end cap 1 for fixation. The function of the end cap 1 is to provide a connection at both ends of the sheep's spine, facilitating subsequent processing and testing. The end cap 1 has a cylindrical structure, fitted over both ends of the sheep's spine, and the gap between them is filled with dental adhesive powder to ensure the stability of the connection. Figure 1 and Figure 2 As shown, a connecting block is provided at the bottom of the end cap 1 to facilitate the connection of the end cap 1 with subsequent processing fixtures and testing equipment.

[0024] ③ Fix both ends of the sheep's spine to two translation fixtures 2, and clamp the middle of the sheep's spine using clamping fixtures 3. The translation fixtures 2 can move the ends of the sheep's spine laterally and longitudinally, and rotate along the axis of the sheep's spine; the clamping fixtures 3 can translate laterally and rotate along the longitudinal and vertical axes. By using the translation fixtures 2 and clamping fixtures 3 to move and deform the sheep's spine, the purpose of simulating scoliosis in the human spine is achieved.

[0025] ④ Using clamping fixture 3, the middle of the sheep's spine is protruded to one side or / and twisted to bend and fix the spine. The intervertebral disc with the greatest degree of lateral curvature is cut open for release, and excess intervertebral discs and adhesions on the lamina are removed. After release, clamping fixture 3 is used again to continue protruding and / or twisting the middle of the sheep's spine until the Cobb angle meets the set requirements and then it is fixed. After fixation, dental tray powder is used to fill the intervertebral space to prevent the sheep's spine from returning to a round shape after the fixture is removed. A thin film is used to cover the dental tray powder during filling to prevent it from flowing out, because the dental tray powder is initially liquid, which is convenient for filling. After filling, it will become fixed, thus achieving fixation. In this embodiment, after the intervertebral disc removal and dental tray powder filling are completed, the entire sheep spine is C-shaped.

[0026] ⑤ After the dental tray powder solidifies, clamping fixture 3 is used to clamp and fix the vertebra above the scoliosis of the sheep's spine. The translation fixture 2 located at the top of the sheep's spine moves and / or rotates to move the sheep's spine, gradually bringing the segment above the scoliosis back to a vertical state. The specific process of verticalization is as follows: when the translation fixture 2 moves and / or rotates the segment of the sheep's spine above the scoliosis to the maximum curvature of the sheep's spine, it is fixed. After fixing, the intervertebral disc with the greatest curvature is cut to release it. After the release is completed, the translation fixture 2 located at the top of the sheep's spine continues to move and / or rotate, bringing the segment above the scoliosis back to a vertical state. After the Cobb angle meets the set requirements, it is fixed. After fixing, dental tray powder is used to fill the intervertebral space, and a film is used to cover it to prevent the dental tray powder from flowing out.

[0027] ⑥ After the dental plaster has solidified, it moves the segment below the scoliosis of the sheep's spine back to a vertical position, using the same method as for the segment above the scoliosis. In this embodiment, clamping fixture 3 holds the vertebra below the scoliosis of the sheep's spine, while translation fixture 2 at the bottom of the sheep's spine moves the spine laterally to a set position. Then, the intervertebral disc with the greatest curvature of the sheep's spine is removed. After removal, the spine continues to move laterally to the segment below the scoliosis, returning it to a vertical position, and is then filled with dental plaster for fixation. The degree of curvature of the sheep's spine is obtained by measuring the Cobb angle.

[0028] After the dental tray powder solidifies, the covering film is removed, and then the deformed simulated sheep spine and end caps are disassembled from the translation fixture 2 and clamping fixture 3.

[0029] The deformed spinal model was completed after the segments above and below the scoliosis of the sheep's spine were straightened back to a vertical position.

[0030] Step S2 includes the following steps: ① Nail path detection: Using a C-arm machine 4, the C-arm machine 4 partially surrounds the sheep's spine, with an X-ray transmitter at one end and an X-ray receiver at the other end. The C-arm machine 4 moves the X-ray transmitter and X-ray receiver along the sheep's spine to perform X-ray scanning on the sheep's spine to determine the position and direction of the nail path.

[0031] ② Drilling: Based on the nail path detection results, drill several bone nail screw holes on the sheep's spine. Specifically, disassemble the X-ray transmitter and receiver on the C-arm machine 4, then install the guide drill sleeve. Use the C-arm machine 4 to fix the guide drill sleeve to ensure accurate drilling positioning. After the guide drill sleeve is fixed, the drill bit passes through the guide drill sleeve to drill, ensuring that the drilling position and direction conform to the settings.

[0032] ③ Inserting the screw: Screw the bone screw 5 into the screw hole. The bone screw 5 includes a shaft that inserts into the screw hole and a fitting connected to the end of the shaft. The fitting includes two arms that hold the titanium rod 6 and a threaded plug 7 between the two arms. Figure 3 As shown, the function of the screw plug 7 is to fix the titanium rod 6 between the two arms.

[0033] ④ Mounting the Rod: First, bend the malleable mandrel to match the curvature of the sheep's spine. Then, connect the bent mandrel to the bone screw 5. Adjust the bending state of the mandrel according to the sheep's spine until it perfectly matches the curvature. Remove the mandrel and use it as a reference for the bending shape and length of the titanium rod 6. Process the titanium rod 6 according to the bending state and length of the mandrel to match the sheep's spine. Then, connect the processed titanium rod 6 to the bone screw 5 to complete the assembly of the test model. The test model can then be assembled into the testing equipment.

[0034] The surface of the mold rod is provided with several length marks that are evenly distributed along its length. The distance between two adjacent length marks is the unit length. The required length of the titanium rod 6 can be quickly determined by the number of length marks.

[0035] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A biomechanical testing method for scoliosis, characterized in that, Includes the following steps: S1. Spine bending in sheep; S2, implant the staple; Step S1 includes the following steps: ① Cutting the sheep spine, including several thoracic vertebrae and several lumbar vertebrae connected to the thoracic vertebrae, while preserving the transverse processes, spinous processes, ligaments and joint capsules of the sheep spine; ② The end caps are placed on the vertebrae at both ends of the sheep's spine for embedding, and dental plaster is filled between the vertebrae and the end caps for fixation; ③ Fix both ends of the sheep spine to two translation fixtures respectively, and use clamping fixtures to clamp the middle of the sheep spine; the two translation fixtures can drive the ends of the sheep spine to move horizontally and longitudinally and rotate along the axis of the sheep spine; the clamping fixtures can translate horizontally, rotate along the longitudinal axis and rotate along the vertical axis. ④ Use a clamping device to cause the middle of the sheep's spine to protrude to one side or / and twist, thus bending and fixing the sheep's spine. Cut open the intervertebral disc with the greatest degree of lateral curvature of the sheep's spine to release it, and remove the excess intervertebral disc and scrape away the intervertebral discs that are adhered to the vertebral lamina. After the release is completed, use the clamping device to continue to cause the middle of the sheep's spine to protrude or / and twist until the Cobb angle meets the set requirements and then fix it. After fixation, use dental tray powder to fill the intervertebral space and use a film to cover it to prevent the dental tray powder from flowing out. ⑤ After the dental tray powder solidifies, use a clamping fixture to clamp and fix the vertebra above the scoliosis of the sheep's spine. The translation fixture at the top of the sheep's spine moves and / or rotates to move the sheep's spine, gradually bringing the segment above the scoliosis back to a vertical position. The process of turning it vertical is as follows: when the translation fixture moves and / or rotates the segment of the sheep's spine above the scoliosis to the maximum curvature of the sheep's spine, it is fixed. After fixing, the intervertebral disc with the greatest curvature is cut open to release it. After the release is completed, the translation fixture at the top of the sheep's spine continues to move and / or rotate, bringing the segment above the scoliosis back to a vertical position, and the Cobb angle meets the set requirements, and is then fixed. After fixing, dental tray powder is used to fill the intervertebral space, and a film is used to cover it to prevent the dental tray powder from flowing out. ⑥ After the dental tray powder solidifies, it helps the segment below the scoliosis of the sheep's spine return to a vertical position. The operation method is the same as that for the segment above the scoliosis of the sheep's spine. After the segments above and below the scoliosis of the sheep's spine have returned to a vertical position, the deformed spine model is completed. Step S2 includes the following steps: ① Pin tract detection: using a C-arm machine for detection; the C-arm machine partially surrounds the sheep's spine, with an X-ray emitting end at one end and an X-ray receiving end at the other end. The C-arm machine moves the X-ray emitting end and the X-ray receiving end to perform X-ray scanning on the sheep's spine to determine the position and direction of the pin tract. ② Drilling: Based on the results of the nail track detection, drill several bone nail screw holes in the sheep's spine; ③ Insert the screw: Screw the bone screw into the screw hole of the bone screw; ④ Mounting the rod: First, bend the malleable rod to match the curvature of the sheep's spine. Then, connect the bent rod to the bone screw. Adjust the bending state of the rod according to the sheep's spine until it perfectly matches the curvature of the sheep's spine, serving as a reference for the bending shape and length of the titanium rod. Process the titanium rod according to the bending state and length of the rod to match the sheep's spine. Then, connect the processed titanium rod to the bone screw to complete the assembly of the test model.

2. The biomechanical testing method for scoliosis according to claim 1, characterized in that, Step S1 further includes: after the dental tray powder solidifies, removing the covering film, and then disassembling the deformed sheep spine and end caps from the translation fixture and clamping fixture.

3. The biomechanical testing method for scoliosis according to claim 1, characterized in that, The bone screw includes a rod portion that is inserted into the screw hole of the bone screw and an insert portion connected to the end of the rod portion; the insert portion includes two arms that hold the titanium rod and a screw plug that is threaded between the two arms.

4. The biomechanical testing method for scoliosis according to claim 1, characterized in that, The drilling step S2 includes: disassembling the X-ray transmitter and X-ray receiver on the C-arm machine, then installing the guide sleeve, and using the C-arm machine to fix the guide sleeve to ensure accurate drilling positioning.

5. The biomechanical testing method for scoliosis according to claim 1, characterized in that, The surface of the mold rod is provided with several length marks evenly distributed along its length; the distance between two adjacent length marks is the unit length, and the required length of the titanium rod can be quickly determined by the number of length marks.

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