Somatosensory method and system based on intervertebral fusion cage implanted in optical fiber

Abstract

The application provides a somatosensory method and system based on an intervertebral fusion cage with an optical fiber inside, and relates to the technical field of intervertebral fusion cages. The method comprises arranging four cascaded optical fiber units arranged in the same direction and in a quadrangular distribution inside four support crossbeams of the intervertebral fusion cage respectively. When the intervertebral fusion cage is pressed, the support crossbeam arranged above the bone window is elastically deformed, four fiber gratings generate corresponding strains, the total pressure received by the intervertebral fusion cage is calculated according to the total strain generated by the four fiber gratings; the moment Mx in the X direction received by the intervertebral fusion cage is calculated according to the strain difference generated by the left two fiber gratings and the right two fiber gratings; the moment My in the Y direction received by the intervertebral fusion cage is calculated according to the strain difference generated by the front two fiber gratings and the back two fiber gratings; the motion state of the lumbar vertebrae is judged through the total pressure, the moment Mx and the moment My, and then the intervertebral fusion condition is evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of intervertebral fusion devices, and in particular to a body sensing method and system based on an optical fiber implanted intervertebral fusion device. Background Art

[0002] Posterior lumbar interbody fusion is a surgical procedure used to treat low back pain and intervertebral disc degeneration. Its goal is to stabilize the spine, relieve pain, and improve neurological function by fusing adjacent vertebrae together. It is suitable for conditions such as intervertebral disc degeneration, spinal stenosis, intervertebral instability, and recurrent disc herniation. However, nonfusion of the bone graft after interbody fusion often leads to a series of serious consequences, such as pedicle screw fracture, fusion cage displacement, and even more serious conditions such as spinal cord and nerve compression.

[0003] Titanium alloy intervertebral fusion cages are commonly used spinal implants, offering excellent biomechanical properties, good early stability, and the convenience of customizing them through 3D printing. However, they also have some drawbacks. During X-ray, CT, and MRI examinations, the presence of metal artifacts can affect image quality, making it difficult to accurately assess bone fusion within the cage. Summary of the Invention

[0004] The purpose of the present invention is to provide a body sensing method and system based on an optical fiber implanted intervertebral fusion cage, so as to solve the problem mentioned in the above background technology that it is difficult to accurately judge the bone fusion status inside the existing intervertebral fusion cage.

[0005] To achieve the above object, the application provides the following technical scheme: a somatosensory method based on an intervertebral fusion cage with an embedded optical fiber, the intervertebral fusion cage with the embedded optical fiber comprising: an intervertebral fusion cage body, the intervertebral fusion cage body having a longitudinally arranged middle through hole and four bone grafting windows arranged transversely, the four bone grafting windows being separated into two rows by the middle through hole, and the middle through hole and the four bone grafting windows dividing the intervertebral fusion cage body into four support beams; four cascaded optical fiber units arranged in the same direction and in a quadrilateral distribution, the four cascaded optical fiber units being arranged inside the four support beams respectively, the cascaded optical fiber unit comprising two fiber Bragg gratings (FBGs), and the eight FBGs corresponding to the upper and lower stress planes of the four bone grafting windows one by one; the method comprising the following steps: when the intervertebral fusion cage with the embedded optical fiber is subjected to pressure, the support beams arranged above the bone grafting windows are elastically deformed, the four FBGs generate corresponding strains, the total pressure Fz of the intervertebral fusion cage with the embedded optical fiber is calculated according to the total strain generated by the four FBGs, the moment Mx of the intervertebral fusion cage with the embedded optical fiber in the X direction is calculated according to the strain difference between the left two FBGs and the right two FBGs, the moment My of the intervertebral fusion cage with the embedded optical fiber in the Y direction is calculated according to the strain difference between the front two FBGs and the back two FBGs, and the mapping relationship between the total pressure Fz, the moment Mx and the moment My and the lumbar motion state is established, and the lumbar motion state is judged through the total pressure Fz, the moment Mx and the moment My, so as to evaluate the intervertebral fusion.

[0006] Optionally, the ends of the intervertebral fusion cage body are tapered on the upper and lower sides, the cascaded optical fiber unit further comprises a temperature measurement module FP, and the four temperature measurement modules FP are arranged close to the tapered surfaces; when the temperature changes, the cavity length of the four temperature measurement modules FP changes, and the center wavelength of the eight FBGs drifts by a corresponding amount; the temperature change value is calculated according to the change amount of the cavity length of the temperature measurement module FP, and the wavelength drift of the FBG is temperature-compensated.

[0007] Optionally, the included angle between the tapered surfaces on the upper and lower sides of the front end of the intervertebral fusion cage body is 50°-70°.

[0008] Optionally, the intervertebral fusion cage with the embedded optical fiber is manufactured by an additive manufacturing method, titanium alloy powder is completely melted by laser scanning, and the cascaded optical fiber unit is implanted in the manufacturing process of the intervertebral fusion cage.

[0009] Optionally, the cascaded optical fiber unit is further metalized, and the metalization comprises activation, sensitization, chemical plating and electroplating.

[0010] Optionally, the diameter of the cascaded optical fiber unit before metallization is 125 μm, the diameter after metallization is 500 μm, the initial cavity length of the temperature measurement module FP is 180 μm, the grating region length of the fiber grating FBG is 5 mm, and the temperature measurement module FP cavity is arranged at the end of the optical fiber.

[0011] Optionally, the step of calculating the total pressure Fz on the optical fiber implanted intervertebral fusion device specifically includes: the arrangement area of ​​the four optical fiber Bragg gratings (FBGs) is a supporting beam with a rectangular cross-section, and when the optical fiber implanted intervertebral fusion device is subjected only to the pressure Fz, the supporting beam undergoes bending deformation, and its maximum deflection is: , where is a uniformly distributed load per unit length, and , is the length of the beam, is the elastic modulus of titanium alloy, is the moment of inertia of the beam section; at this time, the four fiber Bragg gratings (FBGs) will produce the same strain: , where is the dependent variable, is the length of the beam, The maximum deflection is calculated by the maximum strain of the optical fiber, and then the corresponding center wavelength drift of the four fiber gratings FBG are calculated.

[0012] Optionally, the step of calculating the moment Mx in the X direction to which the optical fiber implanted intervertebral fusion device is subjected specifically includes: when the optical fiber implanted intervertebral fusion device is only subjected to the moment Mx, the four supporting beams are subjected to different forces, and the four optical fiber Bragg gratings FBGs will produce strain differences; when the strain difference is greater than 0, the moment Mx is positive, corresponding to the lumbar vertebra bending to the left, and vice versa, it corresponds to the lumbar vertebra bending to the right; the magnitude of the moment Mx reflects the angle of lumbar joint bending; the step of calculating the moment Mx in the X direction to which the optical fiber implanted intervertebral fusion device is subjected specifically includes: when the optical fiber implanted intervertebral fusion device is only subjected to the moment My, the four supporting beams are subjected to different forces, and the four optical fiber Bragg gratings FBGs will produce strain differences; when the strain difference is greater than 0, the moment My is positive, corresponding to the lumbar vertebra bending forward, and vice versa, it corresponds to the lumbar vertebra bending backward; the magnitude of the moment My also reflects the angle of lumbar joint bending.

[0013] Optionally, the step of temperature compensating the wavelength drift of the fiber Bragg grating (FBG) specifically includes: when the ambient temperature changes, the fiber-implanted intervertebral fusion cage will undergo thermal expansion or contraction, and the change in cavity length due to the thermal expansion effect is: , where is the change in cavity length, is the thermal expansion coefficient of the intervertebral fusion cage, is the initial cavity length, is the temperature change; when the ambient temperature changes, the refractive index of the medium in the temperature measurement module FP cavity will also change: , where is the refractive index change, is the thermo-optical coefficient of air, is the temperature change; combined with the thermal expansion effect and the thermo-optical effect, the total cavity length change of the temperature measurement module FP cavity is expressed as: , where is the total cavity length change, is the thermal expansion coefficient of the intervertebral fusion cage, is the initial cavity length, is the temperature change, is the thermo-optical coefficient of air; the temperature compensation of the FBG center wavelength drift is: , where is the center wavelength drift after temperature compensation, is the center wavelength drift, The temperature sensitivity of the four fiber Bragg gratings (FBGs) on the upper surface of the fusion device.

[0014] On the other hand, the present invention also provides a body sensing system based on an optical fiber implanted intervertebral fusion device, comprising: an intervertebral fusion device body, the intervertebral fusion device body having a longitudinally opened middle through hole, and four transversely opened bone grafting windows, the four bone grafting windows being separated into two rows on the left and right by the middle through hole, the middle through hole and the four bone grafting windows separating the intervertebral fusion device body into four supporting beams; four cascaded optical fiber units arranged in the same direction and distributed at four corners, the four cascaded optical fiber units being respectively located inside the four supporting beams, the cascaded optical fiber units comprising two optical fiber gratings FBG, the eight optical fiber gratings FBG corresponding one to one to the upper and lower force planes of the four bone grafting windows; and further comprising: a total pressure Fz measurement module, which is used for causing the supporting beam arranged above the bone grafting window to undergo elastic deformation when the optical fiber implanted intervertebral fusion device is subjected to pressure, and the four optical fiber gratings The gratings FBG generate corresponding strains, and the total pressure Fz on the fiber-optic implanted intervertebral fusion device is calculated according to the total strain generated by the four fiber gratings FBG; the torque Mx measurement module is used to calculate the torque Mx on the fiber-optic implanted intervertebral fusion device in the X direction according to the strain difference generated by the two fiber gratings FBG on the left and the two fiber gratings FBG on the right; the torque My measurement module is used to calculate the torque My on the Y direction on the fiber-optic implanted intervertebral fusion device according to the strain difference generated by the two fiber gratings FBG on the front and the two fiber gratings FBG on the back; the fusion evaluation module is used to establish a mapping relationship between the total pressure Fz, the torque Mx and the torque My and the lumbar vertebrae motion state, and judge the lumbar vertebrae motion state through the total pressure Fz, the torque Mx and the torque My, and then evaluate the intervertebral fusion condition.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] Embedding a cascaded fiber optic unit within the intervertebral fusion cage allows for precise monitoring of the biomechanical state of the spine post-operatively. Four fiber gratings (FBGs) are positioned at the stress-bearing locations corresponding to the bone graft windows—the strain-sensitive areas—to monitor biomechanics in three directions. This addresses the difficulty of assessing bone fusion within metal intervertebral fusion cages. Furthermore, long-term data acquisition provides detailed, real-time feedback, enabling early identification of potential problems. Therefore, the implantation of fiber optic sensors within intervertebral fusion cages has significant practical implications for the success of posterior lumbar intervertebral fusion surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the installation of the optical fiber implanted intervertebral fusion device of the present invention.

[0018] Figure 2 It is an overall schematic diagram of the optical fiber implanted intervertebral fusion device of the present invention.

[0019] Figure 3 This is a layout diagram of the sensitive units of the optical fiber implanted intervertebral fusion device of the present invention.

[0020] Figure 4 This is a diagram showing the main dimensions of the optical fiber implanted intervertebral fusion device of the present invention.

[0021] Figure 5 This is a spectrum diagram of the cascaded optical fiber unit of the present invention.

[0022] In the figure: 1. Fiber-optic intervertebral fusion device; 2. L3 segmental spinal bone; 3. L4 segmental spinal bone; 11. Wedge-shaped surface; 12. Anti-slip serrations; 13. Bone graft window; 14. Middle through hole; 15. Flexible connection thread; 16. Cascaded fiber unit; 161. First FP cavity; 162 - Second FP cavity; 163 - First fiber Bragg grating; 164 - Second fiber Bragg grating, 165 - Third fiber Bragg grating; 166 - Fourth fiber Bragg grating. DETAILED DESCRIPTION

[0023] The following will provide a clear and complete description of the solutions of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of this application refers to the presence of features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or wireless couplings. The term "and / or" used herein includes all or any units and all combinations of one or more associated listed items.

[0026] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0027] It should be understood that the sequence numbers and sizes of the steps in this embodiment do not imply the order of execution. The order of execution of each process is determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of this application.

[0028] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] Please refer to Figure 1-Figure 5 The present invention provides a body sensing method based on an optical fiber implanted intervertebral fusion device, wherein the optical fiber implanted intervertebral fusion device comprises: an intervertebral fusion device body, wherein the intervertebral fusion device body has a longitudinally opened middle through hole and four transversely opened bone grafting windows, wherein the four bone grafting windows are separated into two rows of left and right by the middle through hole, and the middle through hole and the four bone grafting windows separate the intervertebral fusion device body into four supporting beams; four cascaded optical fiber units arranged in the same direction and distributed at four corners, wherein the four cascaded optical fiber units are respectively located inside the four supporting beams, and the cascaded optical fiber units include two optical fiber gratings (FBGs), and the eight optical fiber gratings (FBGs) correspond one to one to the upper and lower force planes of the four bone grafting windows; the method steps comprise: when the optical fiber implanted intervertebral fusion device is under pressure, the supporting beams arranged above the bone grafting windows Elastic deformation occurs, and the four fiber gratings FBGs generate corresponding strains. The total pressure Fz on the fiber-implanted intervertebral fusion device is calculated based on the total strain generated by the four fiber gratings; the torque Mx on the fiber-implanted intervertebral fusion device in the X direction is calculated based on the strain difference generated by the two fiber gratings FBGs on the left and the two fiber gratings FBGs on the right; the torque My on the fiber-implanted intervertebral fusion device in the Y direction is calculated based on the strain difference generated by the two fiber gratings FBGs on the front and the two fiber gratings FBGs on the back; a mapping relationship between the total pressure Fz, the torque Mx and the torque My and the lumbar vertebrae motion state is established, and the lumbar vertebrae motion state is judged by the total pressure Fz, the torque Mx and the torque My, thereby evaluating the intervertebral fusion condition.

[0030] Specifically, the intervertebral fusion cage is prepared by using an additive manufacturing process, and the performance of the intervertebral fusion cage is monitored through information collected during the preparation process, and the process parameters are adjusted. The intervertebral fusion cage comprises upper and lower wedge surfaces, anti-skid serrations, four bone graft windows, connecting threads, and four metalized cascade optical fiber units implanted in the circumference. The cascade optical fiber unit is an FP-FBG-FBG cascade optical fiber. Sixteen anti-skid serrations are arranged in the shape of an inverted triangle, two by two above the beam-like structures of the four bone graft windows, and the rear of the intervertebral fusion cage is provided with connecting threads.

[0031] Specifically, when the intervertebral fusion cage is under pressure, the deformation near the wedge surface is negligible, and the cavity length of the four FP cavities is basically unchanged. The beam-like structure arranged above the bone graft window is elastically deformed, and the four FBGs produce corresponding strains. The total pressure Fz on the intervertebral fusion cage can be obtained according to the total strain generated by the four FBGs. The moment Mx in the X direction on the intervertebral fusion cage can be obtained according to the strain difference generated by the left two FBGs and the right two FBGs. The moment My in the Y direction on the intervertebral fusion cage can be obtained according to the strain difference generated by the front two FBGs and the rear two FBGs.

[0032] Specifically, further, by analyzing and calculating the size and direction of the moments Mx and My, the motion state of the lumbar spine in the forward flexion, backward extension, and left and right lateral bending can be determined, and the intervertebral fusion condition can be evaluated through the actual motion state.

[0033] It can be understood that the cascade optical fiber unit is embedded in the intervertebral fusion cage, and the biomechanical state of the spine can be accurately monitored after the operation. Through the four fiber Bragg gratings FBGs arranged in the strain sensitive area at the corresponding stress position of the bone graft window, the monitoring of the biological force in three directions is realized, and the problem that the metal intervertebral fusion cage is difficult to evaluate the bone fusion condition is solved. In addition, long-term data collection can provide detailed real-time feedback, making it possible to identify potential problems early. Based on this, implanting the optical fiber sensor in the intervertebral fusion cage has important practical significance for the success of the lumbar interbody fusion surgery.

[0034] In some embodiments, the ends of the intervertebral fusion cage body are wedge-shaped on the upper and lower sides, and the cascade optical fiber unit further comprises temperature measurement modules FP, and four temperature measurement modules FP are arranged near the wedge surfaces. When the temperature changes, the cavity length of the four temperature measurement modules FP changes, and at the same time, the center wavelengths of the eight fiber Bragg gratings FBGs produce corresponding drift amounts. The change value of the temperature is calculated through the change amount of the cavity length of the temperature measurement module FP, and the wavelength drift amount of the fiber Bragg grating FBG is temperature compensated.

[0035] In some embodiments, the included angle between the wedge surfaces on the upper and lower sides of the front end of the intervertebral fusion cage body is 50°-70°.

[0036] Specifically, the angle between the wedge-shaped surfaces on the upper and lower sides of the front end of the intervertebral fusion device body is set to 50°-70°, which is convenient for effectively spreading the two vertebrae and providing precise guidance, ensuring the smooth progress of the implantation process. If the angle is too small, it cannot be guaranteed that when the intervertebral fusion device is compressed, the wedge-shaped surfaces will not be deformed by the pressure, thereby ensuring the accuracy of the temperature measurement module FP. If the angle is too large, it is not convenient to effectively spread the two vertebrae and provide precise guidance.

[0037] In some embodiments, the optical fiber implanted intervertebral fusion cage is manufactured using an additive manufacturing method, wherein titanium alloy powder is completely melted by laser scanning, and a cascade optical fiber unit is implanted during the manufacturing process of the intervertebral fusion cage.

[0038] Specifically, the method for preparing an intervertebral fusion device is as follows: creating a three-dimensional model of the intervertebral fusion device and exporting it as an STL file for slicing; setting printing process parameters, laser scanning and printing titanium alloy powder to prepare the intervertebral fusion device base, and pausing the printing process; embedding the prepared metallized cascade optical fiber 16 into the reserved optical fiber arrangement hole and leading its pigtail from the printing device; setting the first layer after the pause layer as the starting layer, and setting the number of prints to 2. The powder coating amount for the second to ninth layers is increased, the powder is re-applied, and a second print is initiated. Real-time cavity length and wavelength information is collected to reconstruct the temperature and strain field during the printing process. Furthermore, a deep learning algorithm is used to determine the powder melting state and bonding strength during the printing process, allowing for timely adjustment of subsequent printing parameters such as scanning speed and laser power to achieve closed-loop control of process parameters. The printing time and number of layers are controlled until the reserved hole for the bioforce monitoring optical fiber is printed, and the second print is completed. The printing process is paused and the metallized cascade optical fiber 16 is embedded. The second print process is repeated three times until the printing is complete.

[0039] In some embodiments, the method further includes metallizing the cascaded optical fiber units, wherein the metallization includes activation, sensitization, chemical plating, and electroplating.

[0040] Specifically, the preparation method of the four metalized cascaded fiber units is as follows: a double-FBG fiber drawing grating fiber with a diameter of 80 μm and a center wavelength of 10 nm is prepared by using a fiber drawing tower grating technology, a phase mask plate and other devices during the fiber drawing process; the coating layers of the prepared double-FBG fiber drawing grating fiber and the hollow core fiber are stripped, and the two fibers are cut on a fiber cutting knife; and the double-FBG fiber drawing grating fiber and the hollow core fiber are placed in a fiber fusion machine for discharge fusion. The electrode discharge generates high temperature, causing the hollow core fiber to collapse and affecting the light path transmission. To avoid serious collapse of the hollow core fiber during the fusion process, the end face of the hollow core fiber is offset by 30 μm from the electrode. In addition, appropriate fusion parameters, including discharge time and discharge intensity, also need to be set. Too long time and too high intensity will also cause the hollow core fiber to collapse seriously. Here, the discharge time is set to 1300 ms, and the discharge intensity is 65 bit. The fused hollow core fiber end is placed in a fiber cutting knife for cutting, and a certain length of the hollow core fiber is reserved as the FP cavity length. The cut hollow core fiber and the single-mode fiber are placed in a fiber fusion machine for fusion. The fused cascaded fiber is metalized, specifically including activation, sensitization, chemical plating and electroplating.

[0041] In some embodiments, the diameter of the cascaded fiber unit before metalization is 125 μm, the diameter after metalization is 500 μm, the initial cavity length of the temperature measurement module FP is 180 μm, the grating length of the fiber grating FBG is 5 mm, and the temperature measurement module FP cavity is arranged at the end of the fiber.

[0042] In some embodiments, the step of calculating the total pressure Fz received by the intervertebral fusion cage implanted in the fiber specifically includes that the arrangement region of the four fiber gratings FBG is a support beam with a rectangular cross section, when the intervertebral fusion cage implanted in the fiber is only subjected to the pressure Fz, the support beam is bent and deformed, and the maximum deflection is: , wherein is the uniformly distributed load per unit length, and , is the length of the beam, is the elastic modulus of titanium alloy, is the moment of inertia of the beam section; at this time, the four fiber gratings FBG produce the same strain, and the maximum strain of the fiber is calculated by the maximum deflection: , wherein is the strain, is the length of the beam, is the maximum deflection, and the corresponding center wavelength drift of the four fiber gratings FBG is calculated.

[0043] Specifically, when the optical fiber implanted intervertebral fusion cage is subjected only to the pressure Fz, the supporting beam is bent and deformed, and the four optical fiber Bragg gratings (FBGs) generate the same strain: , where is the strain of the first fiber Bragg grating, is the strain of the second fiber Bragg grating, is the strain of the third fiber Bragg grating, is the strain of the fourth fiber Bragg grating, is the strain; the corresponding center wavelength drifts are: ,in is the central wavelength drift of the four FBGs on the upper surface of the fusion device; is the initial center wavelength of the four FBGs on the upper surface of the fusion device; is the effective elastic-optical coefficient of the optical fiber core.

[0044] In some embodiments, the step of calculating the moment Mx in the X direction applied to the fiber-optic implanted intervertebral fusion device specifically includes: when the fiber-optic implanted intervertebral fusion device is only subjected to the moment Mx, the four supporting beams are subjected to different forces, and the four fiber gratings FBG will produce strain differences; when the strain difference is greater than 0, the moment Mx is positive, corresponding to the lumbar vertebra bending to the left, and vice versa, it corresponds to the lumbar vertebra bending to the right; the magnitude of the moment Mx reflects the angle of lumbar joint bending; the step of calculating the moment Mx in the X direction applied to the fiber-optic implanted intervertebral fusion device specifically includes: when the fiber-optic implanted intervertebral fusion device is only subjected to the moment My, the four supporting beams are subjected to different forces, and the four fiber gratings FBG will produce strain differences; when the strain difference is greater than 0, the moment My is positive, corresponding to the lumbar vertebra bending forward, and vice versa, it corresponds to the lumbar vertebra bending backward; the magnitude of the moment My also reflects the angle of lumbar joint bending.

[0045] Specifically, when the optical fiber implanted intervertebral fusion device is subjected to only the moment Mx, the four supporting beams are subjected to different forces: ,in , where is the force on the first supporting beam, is the force on the second supporting beam, is the force on the third supporting beam, is the force on the fourth supporting beam, is the distance between two fiber Bragg gratings in the cascaded optical fiber. The four fiber Bragg gratings (FBGs) will generate a strain difference: , where is the x-direction strain of the first fiber Bragg grating, is the strain of the second fiber Bragg grating in the x direction, is the x-direction strain of the third fiber Bragg grating, is the strain of the fourth fiber Bragg grating in the x direction; when When , the moment Mx is positive, corresponding to the lumbar vertebra bending to the left, vice versa, it corresponds to the lumbar vertebra bending to the right; the magnitude of the moment Mx reflects the angle of the lumbar joint bending.

[0046] Similarly, when the optical fiber implanted intervertebral fusion device is subjected only to the moment My, the four supporting beams are subjected to different forces: ,in , where is the force on the first supporting beam, is the force on the second supporting beam, is the force on the third supporting beam, is the force on the fourth supporting beam, is the distance between two fiber Bragg gratings in the cascaded optical fiber. The four fiber Bragg gratings (FBGs) will generate a strain difference: , where is the strain of the first fiber Bragg grating in the y direction, is the strain of the second fiber Bragg grating in the y direction, is the strain of the third fiber Bragg grating in the y direction, is the strain of the fourth fiber Bragg grating in the y direction; when When , the moment My is positive, corresponding to the lumbar vertebra bending forward, vice versa, it corresponds to the lumbar vertebra bending backward; the magnitude of the moment My also reflects the angle of lumbar vertebra joint bending.

[0047] In some embodiments, the step of temperature compensating the wavelength drift of the fiber Bragg grating (FBG) specifically includes: when the ambient temperature changes, the fiber-optic implanted intervertebral fusion cage will undergo thermal expansion or contraction, and the change in cavity length caused by the thermal expansion effect is: , where is the change in cavity length, is the thermal expansion coefficient of the intervertebral fusion cage, is the initial cavity length, is the temperature change; when the ambient temperature changes, the refractive index of the medium in the temperature measurement module FP cavity will also change: , where is the refractive index change, is the thermo-optical coefficient of air, is the temperature change; combined with the thermal expansion effect and the thermo-optical effect, the total cavity length change of the temperature measurement module FP cavity is expressed as: , where is the total cavity length change, is the thermal expansion coefficient of the intervertebral fusion cage, is the initial cavity length, is the temperature change, is the thermo-optical coefficient of air; the temperature compensation of the FBG center wavelength drift is: , where is the center wavelength drift after temperature compensation, is the center wavelength drift, The temperature sensitivity of the four fiber Bragg gratings (FBGs) on the upper surface of the fusion device.

[0048] On the other hand, the present invention also provides a body sensing system based on an optical fiber implanted intervertebral fusion device, comprising: an intervertebral fusion device body, the intervertebral fusion device body having a longitudinally opened middle through hole, and four transversely opened bone grafting windows, the four bone grafting windows being separated into two rows on the left and right by the middle through hole, the middle through hole and the four bone grafting windows separating the intervertebral fusion device body into four supporting beams; four cascaded optical fiber units arranged in the same direction and distributed at four corners, the four cascaded optical fiber units being respectively located inside the four supporting beams, the cascaded optical fiber units comprising two optical fiber gratings FBG, the eight optical fiber gratings FBG corresponding one to one to the upper and lower force planes of the four bone grafting windows; and further comprising: a total pressure Fz measurement module, which is used for causing the supporting beam arranged above the bone grafting window to undergo elastic deformation when the optical fiber implanted intervertebral fusion device is subjected to pressure, and the four optical fiber gratings The gratings FBG generate corresponding strains, and the total pressure Fz on the fiber-optic implanted intervertebral fusion device is calculated according to the total strain generated by the four fiber gratings FBG; the torque Mx measurement module is used to calculate the torque Mx on the fiber-optic implanted intervertebral fusion device in the X direction according to the strain difference generated by the two fiber gratings FBG on the left and the two fiber gratings FBG on the right; the torque My measurement module is used to calculate the torque My on the Y direction on the fiber-optic implanted intervertebral fusion device according to the strain difference generated by the two fiber gratings FBG on the front and the two fiber gratings FBG on the back; the fusion evaluation module is used to establish a mapping relationship between the total pressure Fz, the torque Mx and the torque My and the lumbar vertebrae motion state, and judge the lumbar vertebrae motion state through the total pressure Fz, the torque Mx and the torque My, and then evaluate the intervertebral fusion condition.

[0049] Specifically, through additive manufacturing methods, metallized cascade fiber units are implanted in the manufacturing process of intervertebral fusion cages to achieve temperature and strain field reconstruction during the manufacturing process. Deep learning algorithms are combined for intelligent defect identification to adjust printing parameters in real time, achieve closed-loop control of process parameters, and improve printing quality.

[0050] Specifically, the drawing tower grating technology is used to prepare a cascaded optical fiber unit with a diameter of 80μm. Compared with traditional optical fibers, its diameter is thinner and can better adapt to the thickness of the micro-printing layer of metal additive manufacturing. The prepared optical fiber grating has higher strain sensitivity.

[0051] Specifically, the FP cavity is arranged in the strain-insensitive area of ​​the intervertebral fusion cage, making it sensitive only to temperature, thereby achieving accurate temperature monitoring.

[0052] Specifically, by arranging four FBGs in the strain-sensitive area above the bone graft window, bioforce monitoring in three directions is achieved, solving the problem of difficulty in evaluating bone fusion status in metal intervertebral fusion cages.

[0053] Specifically, a mapping relationship between the moments Mx and My and the lumbar spine motion state was established, enabling real-time feedback on the patient's postoperative spinal curvature angle and degree, creating the possibility of early detection of potential problems.

[0054] Specifically, the FP cavity is placed at the end of the optical fiber, minimizing its negative impact on spectral quality. Furthermore, the FP cavity length signal is used to achieve temperature compensation for the FBG signal, overcoming the FBG's inherent temperature-strain cross-sensitivity and significantly improving the accuracy of bioforce monitoring.

[0055] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0056] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the above-described method embodiments. Any reference to memory, storage, database, or other media used in the embodiments provided by the present invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct RAMbus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM).

[0057] The above are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A body perception method based on an optical fiber implanted intervertebral fusion device, characterized in that: The optical fiber implanted intervertebral fusion device comprises: An intervertebral fusion device body, the intervertebral fusion device body having a longitudinally opened central through hole and four transversely opened bone grafting windows, the four bone grafting windows being separated into two rows by the central through hole, the central through hole and the four bone grafting windows dividing the intervertebral fusion device body into four supporting beams; Four cascaded optical fiber units arranged in the same direction and distributed in four corners, the four cascaded optical fiber units are respectively located inside the four supporting beams, the cascaded optical fiber units include two fiber gratings (FBGs), and the eight fiber gratings (FBGs) correspond one-to-one to the upper and lower force-bearing planes of the four bone graft windows; The method steps include: When the optical fiber implanted intervertebral fusion device is under pressure, the supporting beam arranged above the bone graft window undergoes elastic deformation, and the four optical fiber Bragg gratings (FBGs) generate corresponding strains. The total pressure Fz exerted on the optical fiber implanted intervertebral fusion device is calculated based on the total strain generated by the four optical fiber Bragg gratings. The moment Mx in the X direction on the optical fiber implanted intervertebral fusion device is calculated based on the strain difference generated by the two optical fiber Bragg gratings (FBGs) on the left and the two optical fiber Bragg gratings (FBGs) on the right; The moment My in the Y direction on the optical fiber implanted intervertebral fusion device is calculated based on the strain difference between the two front optical fiber Bragg gratings (FBGs) and the two rear optical fiber Bragg gratings (FBGs); Establishing a mapping relationship between the total pressure Fz, the moment Mx, and the moment My and the motion state of the lumbar spine, and judging the motion state of the lumbar spine by the total pressure Fz, the moment Mx, and the moment My, and then evaluating the intervertebral fusion condition; The upper and lower sides of the end of the intervertebral fusion cage body are gradually converged into wedge-shaped surfaces, and the cascade optical fiber unit further includes a temperature measurement module FP, and four of the temperature measurement modules FP are arranged close to the wedge-shaped surfaces; When the temperature changes, the cavity lengths of the four temperature measurement modules FP change, and at the same time, the center wavelengths of the eight fiber gratings FBG produce corresponding drifts; the temperature change value is calculated by the change in the cavity length of the temperature measurement module FP, and the wavelength drift of the fiber grating FBG is temperature compensated.

2. The body perception method based on optical fiber implanted intervertebral fusion cage according to claim 1, characterized in that: The angle between the wedge-shaped surfaces on the upper and lower sides of the front end of the intervertebral fusion cage body is 50°-70°.

3. The body perception method based on optical fiber implanted intervertebral fusion cage according to claim 1, characterized in that: The optical fiber implanted intervertebral fusion device adopts an additive manufacturing method, completely melts titanium alloy powder through laser scanning, and implants a cascade optical fiber unit during the manufacturing process of the intervertebral fusion device.

4. The body perception method based on optical fiber implanted intervertebral fusion cage according to claim 1, characterized in that: The method further includes metallizing the cascaded optical fiber unit, wherein the metallization includes activation, sensitization, chemical plating, and electroplating.

5. The body perception method based on optical fiber implanted intervertebral fusion cage according to claim 1, characterized in that: The diameter of the cascaded optical fiber unit before metallization is 125 μm, and the diameter after metallization is 500 μm. The initial cavity length of the temperature measurement module FP is 180 μm, the grating region length of the fiber grating FBG is 5 mm, and the temperature measurement module FP cavity is arranged at the end of the optical fiber.

6. The body perception method based on optical fiber implanted intervertebral fusion cage according to claim 1, characterized in that: The step of calculating the total pressure Fz on the optical fiber implanted intervertebral fusion device specifically includes: The arrangement area of ​​the four fiber gratings FBG is a supporting beam with a rectangular cross section. When the optical fiber implanted intervertebral fusion device is subjected only to the pressure Fz, the supporting beam bends and deforms, and its maximum deflection is: , where is a uniformly distributed load per unit length, and , is the length of the beam, is the elastic modulus of titanium alloy, is the moment of inertia of the beam section; At this time, the four fiber gratings FBG will produce the same strain, and the maximum strain of the optical fiber can be calculated by the maximum deflection: , where is the dependent variable, is the length of the beam, is the maximum deflection, and then the corresponding center wavelength drifts of the four fiber gratings FBG are calculated.

7. The body perception method based on optical fiber implanted intervertebral fusion cage according to claim 1, characterized in that: The step of calculating the moment Mx in the X direction on the optical fiber implanted intervertebral fusion device specifically includes: When the fiber-optic intervertebral fusion device is subjected only to the torque Mx, the four supporting beams are subjected to different forces, and the four fiber gratings (FBGs) will produce strain differences. When the strain difference is greater than 0, the torque Mx is positive, corresponding to the lumbar vertebra bending to the left, and vice versa, corresponding to the lumbar vertebra bending to the right. The magnitude of the torque Mx reflects the angle of lumbar vertebral joint bending. The step of calculating the moment Mx in the X direction on the optical fiber implanted intervertebral fusion device specifically includes: When the optical fiber implanted intervertebral fusion device is only subjected to the torque My, the four supporting beams are subjected to different forces, and the four optical fiber Bragg gratings (FBGs) will produce strain differences. When the strain difference is greater than 0, the torque My is positive, corresponding to the lumbar vertebra bending forward, and vice versa, it corresponds to the lumbar vertebra bending backward. The magnitude of the torque My also reflects the angle of lumbar joint bending.

8. The body perception method based on optical fiber implanted intervertebral fusion cage according to claim 1, characterized in that: The step of performing temperature compensation on the wavelength drift of the fiber grating (FBG) specifically includes: When the ambient temperature changes, the optical fiber implanted intervertebral fusion cage will undergo thermal expansion or contraction. The change in cavity length due to the thermal expansion effect is: , where is the change in cavity length, is the thermal expansion coefficient of the intervertebral fusion cage, is the initial cavity length, is the temperature change; When the ambient temperature changes, the refractive index of the medium in the temperature measurement module FP cavity will also change: , where is the refractive index change, is the thermo-optical coefficient of air, is the temperature change; Combining the thermal expansion effect and the thermo-optical effect, the total cavity length change of the temperature measurement module FP cavity is expressed as: , where is the total cavity length change, is the thermal expansion coefficient of the intervertebral fusion cage, is the initial cavity length, is the temperature change, is the thermo-optical coefficient of air; Temperature compensation for FBG center wavelength drift: , where is the center wavelength drift after temperature compensation, is the center wavelength drift, The temperature sensitivity of the four fiber Bragg gratings (FBGs) on the upper surface of the fusion device.

9. A body sensing system based on an optical fiber implanted intervertebral fusion device, characterized in that: include: An intervertebral fusion device body, the intervertebral fusion device body having a longitudinally opened central through hole and four transversely opened bone grafting windows, the four bone grafting windows being separated into two rows by the central through hole, the central through hole and the four bone grafting windows dividing the intervertebral fusion device body into four supporting beams; Four cascaded optical fiber units arranged in the same direction and distributed in four corners, the four cascaded optical fiber units are respectively located inside the four supporting beams, the cascaded optical fiber units include two fiber gratings (FBGs), and the eight fiber gratings (FBGs) correspond one-to-one to the upper and lower force-bearing planes of the four bone graft windows; Also includes: a total pressure Fz measurement module, configured to calculate the total pressure Fz exerted on the fiber-optic intervertebral fusion device based on the total strain generated by the four fiber gratings (FBGs), when the fiber-optic intervertebral fusion device is subjected to pressure, causing the support beam arranged above the bone graft window to elastically deform and the four fiber gratings (FBGs) to generate corresponding strain; a torque Mx measurement module, configured to calculate the torque Mx in the X direction exerted on the optical fiber implanted intervertebral fusion device according to the strain difference generated by the two optical fiber Bragg gratings (FBGs) on the left and the two optical fiber Bragg gratings (FBGs) on the right; a torque My measurement module, configured to calculate the torque My in the Y direction exerted on the optical fiber implanted intervertebral fusion device based on the strain difference between the two front optical fiber Bragg gratings (FBGs) and the two rear optical fiber Bragg gratings (FBGs); a fusion assessment module, configured to establish a mapping relationship between the total pressure Fz, the moment Mx, and the moment My and the motion state of the lumbar spine, and to determine the motion state of the lumbar spine based on the total pressure Fz, the moment Mx, and the moment My, thereby assessing the intervertebral fusion condition; The upper and lower sides of the end of the intervertebral fusion cage body are gradually converged into wedge-shaped surfaces, and the cascade optical fiber unit further includes a temperature measurement module FP, and four of the temperature measurement modules FP are arranged close to the wedge-shaped surfaces; When the temperature changes, the cavity lengths of the four temperature measurement modules FP change, and at the same time, the center wavelengths of the eight fiber gratings FBG produce corresponding drifts; the temperature change value is calculated by the change in the cavity length of the temperature measurement module FP, and the wavelength drift of the fiber grating FBG is temperature compensated.

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