Optical fiber sensing system and method for on-line monitoring in human knee arthroplasty

Abstract

The invention discloses an optical fiber sensing system and method for on-line monitoring in human knee arthroplasty. The optical fiber sensing system comprises an optical fiber grating pressure sensing probe 1, a sensing optical cable 2, a signal acquisition and communication module 3, an optical fiber grating demodulation module 4 and a computer display module 5, the pressure sensing probe is connected to the fiber bragg grating demodulation and processing module through a transmission optical cable for signal decoupling, result data is transmitted to the computer for processing through the signal acquisition and communication module, the influence of temperature fluctuation on the measurement precision is eliminated through a difference algorithm, and the display screen displays the pressure at different positions in the operation process in real time. And chart analysis and surgical operation parameter AI optimization can be carried out on the stored data. Due to the application of the system technology, inherent defects of knee joint balance caused by subjective judgment of surgeons are greatly reduced, reference can be provided for the doctors to evaluate soft tissue tension in total knee arthroplasty, and then the success rate of the operation is increased.

Description

Technical Field

[0001] The invention relates to the field of medical instruments, and in particular to an optical fiber sensing online monitoring system and method for human knee joint surgery. Background Art

[0002] The knee joint is the most important and complex joint in the human body. It bears the weight of the human body or even several times that of the human body. With the acceleration of the aging of the population in my country, the incidence of knee joint diseases is also increasing. For knee joints that have already developed severe inflammation, the most effective method is to undergo artificial knee replacement. With the rapid growth of the number of knee replacement surgeries in my country, how to reduce the incidence of soft tissue imbalance during surgery has become an important issue at present. At present, the traditional evaluation methods for soft tissue balance of the knee joint during knee replacement surgery mainly rely on the surgeon's experience and subjective evaluation. The inaccuracy of these evaluation methods can easily lead to soft tissue imbalance. Due to the different experience and basis of the surgeon, the subjective evaluation method has poor reliability and stability and cannot achieve a quantitative evaluation of soft tissue balance. Therefore, it is necessary to introduce sensors during surgery to assist doctors in determining soft tissue balance and reduce the influence of doctors' subjective factors. At present, there are several methods for measuring soft tissue balance during artificial knee replacement surgery:

[0003] 1. A Chinese patent (CN205612482U) discloses a system for measuring the soft tissue pressure and trajectory of a human knee joint, which includes a measuring device and a display device; the measuring device is placed between the femoral prosthesis and the tibial prosthesis, and the thin film sensor thereon generates a pressure signal under pressure, which is sent to the display device through a Bluetooth module. After the osteotomy of the artificial knee joint is completed, the measuring device is first turned on by a switch, and then the measuring device is placed on the patient's tibial platform to obtain the pressure and the movement trajectory of the femur, and sent to the display device through a Bluetooth module. The doctor can intuitively understand the pressure distribution state of the tibial platform and the movement trajectory of the femoral prosthesis through the display device, which is convenient for real-time guidance of the doctor to complete accurate soft tissue release and realize individualized treatment. However, the above technology has some defects: the sensor contained in the above pressure measuring device is susceptible to electromagnetic interference and does not have an explosion-proof function; in addition, the use of this electrical sensor for measurement has the disadvantages of low sensitivity, high temperature resistance, and poor corrosion resistance.

[0004] 2. Lin Qihang. Research on pressure sensor array for soft tissue balance measurement in joint replacement surgery [D]. Suzhou University, 2021 A flexible pressure sensor for soft tissue balance measurement is proposed. The smart gasket is inserted into the knee joint after osteotomy for monitoring, and the data is transmitted to the computer through a wire for processing and display. However, the sensor described in the invention content is a piezoelectric sensor, which is susceptible to electromagnetic interference and does not have explosion-proof function; at the same time, the sensor can only measure the pressure value of the corresponding point, and cannot cover the entire surface of the tibial gasket, so the measurement range is extremely limited.

[0005] At present, there are few literatures on soft tissue balance monitoring in human knee replacement surgery. The existing monitoring methods mainly use electrical sensors for monitoring. Since electrical sensors themselves are susceptible to electromagnetic interference and do not have explosion-proof functions, it is difficult to network when using multi-point measurement, which limits the timely processing of signals. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a fiber optic sensing system and method for online monitoring during human knee replacement surgery. Since the optical fiber itself is a passive device, it has many advantages such as anti-electromagnetic interference, light weight, small size, high sensitivity, corrosion resistance, and good long-term stability. The use of this monitoring system can realize real-time measurement of soft tissue tension during human knee surgery. The application of intraoperative sensor technology greatly reduces the inherent defects of knee joint pressure balance caused by the surgeon's subjective judgment, and can assist doctors to observe the patient's soft tissue balance at any time and select the most suitable tibial gasket for the patient.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0008] A fiber optic sensing system for online monitoring during human knee replacement surgery comprises a fiber optic Bragg grating pressure sensing probe 1, a sensing optical cable 2, a signal acquisition and communication module 3, a fiber optic Bragg grating demodulation module 4, and a computer display module 5; the fiber optic Bragg grating pressure sensing probe 1 comprises a fiber optic Bragg grating array 11, a conformal elastic sensitive unit 12, a flexible coating 13, a transmission optical cable 14, a lead-out tube 15, and a biological gel 16; during human knee replacement surgery, the fiber optic Bragg grating pressure sensing probe 1 is pasted on an artificial tibia trial mold of the patient through the biological gel, and the pressure distribution on the artificial tibia trial mold is sensed through the grating; the pressure sensing probe is connected to the fiber optic Bragg grating demodulation and processing module through the transmission optical cable for signal decoupling, and the result data is transmitted to the computer for processing through the signal acquisition and communication module, and the display screen displays the pressure magnitude at different positions during the operation in real time.

[0009] In the optical fiber sensing system, the conformal elastic sensitive unit 12 is formed by laser welding two stamped high-elastic stainless steel sheets with a concave structure. After the optical fiber Bragg grating is pasted on the stamped concave surface, the two stamped stainless steel sheets are laser welded together, and the surface of the conformal elastic sensitive unit 12 is covered with a flexible coating 13 to protect the conformal elastic sensitive unit 12.

[0010] The optical fiber sensing system adopts three optical fiber gratings with diameters of 50μm to 125μm. After the optical fiber gratings are pasted on the stamping concave surface, two stamping blocks are welded by laser, and the surface is protected by a uniform human biocompatible flexible coating to conformal elastic sensitive units.

[0011] In the optical fiber sensing system, the conformable elastic sensitive unit 12 is of a crescent shape, which is the same shape as the artificial tibia trial mold implanted in the knee joint, and the overall thickness does not exceed 1 mm.

[0012] The optical fiber sensing system and the pressure sensing probe are arranged on the tibia trial mold in the form of surface bonding, and can be used immediately after bonding.

[0013] The fiber optic sensing system uses three fiber gratings. When pressure is applied to the probe, the grating of the conformal elastic sensitive unit is driven to produce strain. If the wavelength changes of any two gratings are in opposite directions, it means that the force application point is on the side of the grating with a smaller wavelength; if the wavelengths of any two gratings are both larger, it means that the force application point is in the middle position; the pressure distribution at the corresponding front, middle and back positions on the artificial tibia trial model during the pressure application process is obtained by measuring the size of the wavelength change of the gratings at different positions.

[0014] The optical fiber sensing system uses the difference between the center wavelengths of the two front and rear gratings in signal demodulation to eliminate the common mode signal caused by temperature on the center wavelength of the grating, thereby eliminating the influence of temperature fluctuations; at the same time, the measured data is fitted using a high-precision least squares method and a polynomial algorithm to obtain a more precise, direct and accurate measurement of the pressure distribution between the tibial pad test mold and the femoral condyle test mold, with higher accuracy.

[0015] The optical fiber sensing system and the computer can display the pressure values ​​of the inner and outer sides of the artificial tibia trial model, the pressure difference between the inner and outer sides, and the movement trajectory of the femur.

[0016] An online monitoring method during human knee replacement surgery based on any of the fiber optic sensing systems.

[0017] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0018] The monitoring system senses the pressure distribution by directly attaching the pressure sensor probe to the artificial tibial trial mold. The system is simple to operate and easy to monitor. It can be well applied to tibial prostheses of different specifications and has better versatility.

[0019] This monitoring system uses a fast signal processing method to quickly analyze and judge the collected data signals, cache the data and display the knee joint pressure balance status in real time. This product's "bridge structure" design, combined with the fiber grating detection principle and direct attachment detection form, can achieve higher detection accuracy.

[0020] This monitoring system can monitor the soft tissue balance status during knee surgery in real time. At the same time, based on big data and AI intelligence, it can propose corresponding solutions for selection to assist doctors in subsequent operations.

[0021] The sensor part of this monitoring system has a low manufacturing cost and uses a new biocompatible material. It has strong universality and three specifications can meet the needs of clinical use. It cleverly balances performance and price, allowing more people to easily afford and enjoy the convenience and efficiency it brings.

[0022] This monitoring system adopts all-fiber detection technology, which has many advantages such as anti-electromagnetic interference, light weight, small size, high sensitivity, corrosion resistance, good long-term stability, and easy reuse, which greatly improves the success rate of knee surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of an artificial knee joint model.

[0024] Figure 2 It is a schematic diagram of the structure of a fiber Bragg grating pressure sensor probe.

[0025] Figure 3 It is a schematic diagram of the overall structure of the monitoring system of the present invention.

[0026] Numbers in the figure: 1. Fiber Bragg grating pressure sensing probe; 2. Sensing optical cable; 3. Signal acquisition and communication module; 4. Fiber Bragg grating demodulation module; 5. Computer; 6. Human tibial prosthesis; 8. Artificial tibial test model; 9. Tibia; 11. Flexible fiber Bragg grating array; 12. Conformal elastic sensitive unit; 13. Flexible coating; 14. Transmission optical cable; 15. Lead-out tube; 16. Biogel; DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with specific embodiments.

[0028] Figure 1It is a schematic diagram of a model of an artificial knee joint prosthesis. After the doctor completes the osteotomy operation, an artificial tibia trial mold 8 is implanted therein. The fiber grating pressure sensing probe 1 of the present invention is located on the artificial tibia trial mold 8.

[0029] Figure 2 It is a schematic diagram of the structure of a fiber Bragg grating pressure sensing probe. The fiber Bragg grating pressure sensing probe 1 of the present invention comprises a flexible fiber Bragg grating array 11, a conformable elastic sensitive unit 12, a flexible coating 13 (made of thin polyimide or silicone with human biocompatibility), a transmission optical cable 14, a lead-out tube 15, and a bio-gel 16. The conformable elastic sensitive unit 12 is formed by laser welding two stamped high elastic stainless steel sheets with a concave structure, one end of which is provided with a micro-hole as a channel for the lead-out tube 15, and the lead-out tube 15 accommodates the transmission optical cable 14. After the fiber Bragg grating with a diameter of 50 μm to 125 μm is pasted on the stamped concave surface, the two stamped stainless steel sheets are laser welded together, and the surface of the conformable elastic sensitive unit 12 is covered with a flexible coating 13 to protect the conformable elastic sensitive unit 12. When using the bio-gel, directly tear off the release paper on the surface, and paste it on the artificial tibia trial mold through the bio-gel.

[0030] Figure 3 It is a schematic diagram of a fiber optic sensing system for online monitoring of human knee joints described in the present invention, including a fiber optic Bragg grating pressure sensing probe 1, a sensing optical cable 2, a signal acquisition and communication module 3, a fiber optic Bragg grating demodulation module 4, and a computer display module 5; the fiber optic Bragg grating pressure sensing probe 1 is pasted between the femoral prosthesis and the tibial plateau of the patient, and the pressure distribution on the tibial plateau is sensed by the pressure sensor; the fiber optic Bragg grating pressure sensing probe 1 is connected to the signal acquisition and processing module 3 through the transmission optical cable 2, and the signal acquisition and communication module 3 is connected to the fiber optic Bragg grating demodulation module 4, and finally the result is transmitted to the computer 5. The above contents constitute the basic structure of the present invention.

[0031] The present invention adopts such a structural setting. After the doctor completes the osteotomy, the fiber Bragg grating pressure sensing probe 1 is pasted on the artificial tibial test mold. When the doctor drives the patient's femur to flex and extend, pressure is generated at different positions on the surface of the tibial test membrane. The gratings at different positions in the pressure sensing probe sense the pressure changes, and the pressure distribution of the patient's tibial platform can be monitored in real time. The fiber Bragg grating pressure sensing probe 1 transmits the acquired pressure information to the signal acquisition and communication module 3 in real time through the sensing optical cable 2. After processing, the signal is transmitted to the fiber Bragg grating demodulation module 4 to obtain the corresponding digital signal. The fiber Bragg grating demodulation module 4 transmits the signal to the computer 5. The doctor assists in judging whether soft tissue release is needed in the future and what type of joint gasket to choose based on the final display result.

[0032] In actual applications, external pressure acts on the patient's femur, and the femoral prosthesis transmits the pressure to the fiber Bragg grating pressure sensing probe 1. When the probe is pressurized, the grating of the conformal elastic sensitive unit is strained. The three gratings used in the present invention are arranged in a straight line. The present invention determines the specific position of the force application point by the following method. If the wavelength change directions of any two gratings are opposite, it means that the force application point is on the side of the grating with a smaller wavelength; if the wavelengths of any two gratings are both enlarged, it means that the force application point is in the middle. The pressure distribution of the corresponding front, middle and back positions on the test membrane during the pressure application process is obtained by measuring the size of the wavelength change of the gratings at different positions.

[0033] In signal demodulation, the difference between any two grating center wavelengths is used to remove the common mode signal caused by temperature on the grating center wavelength, thereby eliminating the influence of temperature fluctuations.

[0034] At the same time, the measured data is fitted using high-precision least squares method and polynomial algorithm to obtain a more precise, direct and accurate measurement of the pressure distribution between the tibial pad test mold and the femoral condyle test mold with higher accuracy.

[0035] The fiber Bragg grating demodulation unit 4 timely decouples the pressure acting on the femoral pad, and the doctor determines the subsequent operation based on the result. The knee joint online monitoring system can monitor the status of multiple knee joint surgeries at the same time through the same instrument and wavelength division multiplexing technology, greatly improving the efficiency of the operation.

[0036] This monitoring system adopts all-fiber detection technology, which has many advantages such as anti-electromagnetic interference, light weight, small size, high sensitivity, corrosion resistance, good long-term stability, and easy reuse, which greatly improves the success rate of knee surgery.

[0037] The fiber grating pressure sensing probe 1 adopts a wrapping structure, the middle layer adopts a conformable elastic sensitive unit, and the outer layer adopts a human biocompatible silicone flexible coating. It is elastic at room temperature, can produce a large deformation under a very small external force, and can return to its original state after the external force is removed. It also has excellent biocompatibility and non-toxicity. Such a structural setting can effectively protect the sensor without affecting the working performance of the sensor.

[0038] The computer 5 can provide a variety of pressure images for doctors to choose from, and can recommend a reasonable surgical plan to doctors based on big data and AI intelligence. With such a structural setting, doctors can have more diverse choices and further improve the success rate of surgery.

[0039] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A fiber optic sensing system for online monitoring of human knee replacement surgery, characterized in that: The invention comprises a fiber Bragg grating pressure sensing probe (1), a sensing optical cable (2), a signal acquisition and communication module (3), a fiber Bragg grating demodulation module (4), and a computer display module (5); the fiber Bragg grating pressure sensing probe (1) comprises a fiber Bragg grating array (11), a conformal elastic sensitive unit (12), a flexible coating (13), a transmission optical cable (14), a lead-out tube (15), and a biological gel (16); during human knee replacement surgery, the fiber Bragg grating pressure sensing probe (1) is pasted onto the patient's artificial tibia trial mold via the biological gel, and the pressure distribution on the artificial tibia trial mold is sensed via the grating; the pressure sensing probe is connected to the fiber Bragg grating demodulation and processing module via the transmission optical cable for signal decoupling, and the result data is transmitted to the computer for processing via the signal acquisition and communication module, and the display screen displays the pressure magnitude at different positions during the surgical process in real time.

2. The optical fiber sensing system according to claim 1, characterized in that: The conformal elastic sensitive unit (12) is formed by laser welding two stamped high elastic stainless steel sheets with concave structures. After the optical fiber grating is pasted on the stamped concave surface, the two stamped stainless steel sheets are laser welded together. The surface of the conformal elastic sensitive unit (12) is covered with a flexible coating (13) to protect the conformal elastic sensitive unit (12).

3. The optical fiber sensing system according to claim 1, characterized in that: Three fiber gratings with diameters of 50 μm to 125 μm are used. After the fiber gratings are pasted on the stamping concave surface, two stamping blocks are welded by laser, and the surface is protected by a uniform human biocompatible flexible coating to protect the conformal elastic sensitive unit.

4. The optical fiber sensing system according to claim 1, characterized in that: The conformable elastic sensitive unit (12) is in a crescent shape, which is the same shape as the tibial pad implanted in the knee joint, and the overall thickness does not exceed 1 mm.

5. The optical fiber sensing system according to claim 1, characterized in that: The pressure sensing probe is arranged on the tibia trial mold in the form of surface pasting, and can be used immediately after pasting.

6. The optical fiber sensing system according to claim 1, characterized in that: Three fiber Bragg gratings are used. When pressure is applied to the probe, the gratings of the conformal elastic sensitive unit are driven to produce strain. If the wavelength changes of any two gratings are in opposite directions, it means that the force application point is on the side of the grating with a smaller wavelength; if the wavelengths of any two gratings are both enlarged, it means that the force application point is in the middle position. The pressure distribution at the corresponding front, middle and back positions on the artificial tibia trial model during pressure application is obtained by measuring the size of the wavelength change of the gratings at different positions.

7. The optical fiber sensing system according to claim 1, characterized in that: In signal demodulation, the difference between the center wavelengths of the two gratings is used to eliminate the common mode signal caused by temperature on the center wavelength of the grating, thereby eliminating the influence of temperature fluctuations; at the same time, the measured data is fitted using the least squares method and polynomial algorithm.

8. The optical fiber sensing system according to claim 1, characterized in that: The computer can display the pressure values ​​of the inner and outer sides of the tibial pad, the pressure difference between the inner and outer sides, and the movement trajectory of the femur.

9. A method for online monitoring during human knee replacement surgery using a fiber optic sensing system according to any one of claims 1-8.

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