A pressure measuring device and method during knee replacement surgery

Abstract

The present application provides a pressure measurement device and method during knee replacement surgery, which belongs to the field of medical device technology. The device includes: a pressure sensing unit, which is used to detect the knee joint pressure of the object under test and convert the knee joint pressure into a sensing capacitance signal; a signal processing unit, which is used to convert the sensing capacitance signal into a detection voltage signal, and obtain the knee joint pressure value based on the detection voltage signal; an inertial sensing unit, which is respectively configured on the ankle and thigh of the object under test, and is used to measure the leg posture data of the object under test; a receiving unit, which is used to receive the knee joint pressure value and the leg posture data and transmit the knee joint pressure value and the leg posture data to an electronic device; an electronic device, which is used to generate the knee joint pressure distribution data between the femur and the tibia of the object under test at different posture angles based on the knee joint pressure value and the leg posture data. The present application improves the accuracy of the knee joint pressure balance measurement at different angles.

Description

Technical Field

[0001] The present application relates to the technical field of medical devices, and in particular to a pressure measurement device and method during knee replacement surgery. Background Art

[0002] Knee osteoarthritis (OA) is a common chronic joint disease characterized by degeneration of articular cartilage. Total knee arthroplasty (TKA) replaces the damaged joint surface by inserting a special metal component and a high-molecular polyethylene liner between the femur and tibia, which can effectively relieve pain and restore joint function. It is an ideal choice for treating severe knee joint diseases.

[0003] In the early stages of knee replacement surgery, intraoperative evaluation of the reconstructed joint is highly subjective. The evaluation process usually involves the surgeon manually placing the leg in different positions and repeatedly moving the joint through different degrees of leg flexion and extension, while visually evaluating the range of motion and relative stability of the joint. Intraoperative evaluation is highly subjective, and the performance of the reconstructed joint depends largely on the surgeon's level of experience. Currently, there are devices that can accurately measure pressure inside and outside the knee joint, but these devices still require the surgeon to manually place the leg in different positions and control the tibia and femur to form different angles to measure the changes in pressure at different angles of the knee joint, thereby determining whether the pressure in the knee joint is balanced.

[0004] However, this method relies on the doctor's adjustment of the leg posture. In actual operation, there may be errors in the angles of the tibia and femur, which in turn affects the accuracy of measuring the pressure balance of the knee joint. Summary of the invention

[0005] The purpose of the present application is to provide a pressure measurement device and method during knee replacement surgery to solve the above-mentioned problems.

[0006] To achieve the above objectives, in a first aspect, the present application proposes a pressure measurement device during knee replacement surgery, the device comprising:

[0007] A pressure sensing unit, comprising an ion-type pressure sensor array arranged in an array form of m rows and n columns, the ion-type pressure sensor array is used to detect the knee joint pressure of the object under test and convert the knee joint pressure into a sensing capacitance signal, m and n are integers greater than or equal to 1;

[0008] A signal processing unit, connected to the ion-type pressure sensor array, for converting the sensing capacitance signal generated by the ion-type pressure sensor array into a detection voltage signal, and obtaining a knee joint pressure value based on the detection voltage signal;

[0009] Inertial sensor units are respectively arranged on the ankles and thighs of the measured object, and are used to measure the leg posture data of the measured object;

[0010] a receiving unit, connected to the electronic device, for receiving the knee joint pressure value and the leg posture data and transmitting the knee joint pressure value and the leg posture data to the electronic device;

[0011] An electronic device is used to receive the knee joint pressure value and the leg posture data from the receiving unit, and generate knee joint pressure distribution data at different posture angles between the femur and tibia of the object under test based on the knee joint pressure value and the leg posture data.

[0012] In some embodiments, the inertial sensing unit includes at least one accelerometer and at least one gyroscope, which are used to measure static posture information and dynamic rotation information of the object under measurement, and fuse the static posture information and dynamic rotation information to obtain leg posture data of the object under measurement.

[0013] In some embodiments, the at least one acceleration sensor is used to measure the linear acceleration of the object under test in the three-axis directions of the spatial coordinate system to obtain static posture information of the object under test, and the at least one gyroscope is used to measure the angular velocity of the object under test in the three-axis directions of the spatial coordinate system to obtain dynamic rotation information of the object under test.

[0014] In some embodiments, the electronic device is configured to:

[0015] defining the initial posture of the legs of the measured object as an initial quaternion;

[0016] updating the initial quaternion according to the dynamic rotation information to reflect the leg movement of the subject;

[0017] The updated quaternion is corrected according to the static attitude information to eliminate the error caused by the gyroscope drift.

[0018] In some embodiments, the electronic device is also used to convert the corrected quaternion into a rotation matrix to calculate the posture angle between the femur and tibia of the subject, and calculate the knee joint pressure correction value under different posture angles between the femur and tibia of the subject based on the posture angle and the knee joint pressure value.

[0019] In some embodiments, the driving end of each row of the ion-type pressure sensor in the ion-type pressure sensor array is configured to input an excitation voltage, and the excitation voltage includes a positive excitation voltage and a negative excitation voltage that are input alternately;

[0020] The signal processing unit comprises:

[0021] At least one capacitance-to-pressure conversion circuit, each of which includes an operational amplifier and a reference capacitor, wherein two ends of the reference capacitor are respectively connected to an inverting input terminal and an output terminal of the operational amplifier, wherein the inverting input terminal of the operational amplifier is configured to be connected to a detection terminal of an ion-type pressure sensor of a corresponding column in the ion-type pressure sensor array; the non-inverting input terminal of the operational amplifier is configured to input a reference voltage, and the output terminal of the operational amplifier is configured to output a first detection voltage and a second detection voltage corresponding to the positive excitation voltage and the negative excitation voltage, respectively, when a positive excitation voltage and a negative excitation voltage are alternately input to a driving terminal of an ion-type pressure sensor of a target row in the ion-type pressure sensor array;

[0022] A control unit is connected to the output end of the operational amplifier, and is used to calculate the capacitance value of the ion-type pressure sensor in the target row in the ion-type pressure sensor array based on the amplitudes of the positive excitation voltage and the negative excitation voltage, the first detection voltage and the second detection voltage, and the capacitance value of the reference capacitor, and convert the capacitance value of the ion-type pressure sensor in the target row into the knee joint pressure value.

[0023] In some embodiments, the signal processing unit further includes a multi-way selection unit, which is used to sequentially connect the detection ends of at least one column of the ion-type pressure sensors in the ion-type pressure sensor array to the inverting input end of at least one operational amplifier.

[0024] In some embodiments, the signal processing unit is configured to automatically adjust the amplitudes of the positive excitation voltage and the negative excitation voltage according to the leg posture data of the subject to match the sensing accuracy requirements of the knee joint pressure of the subject under different leg postures.

[0025] In some embodiments, the signal processing unit is configured to increase the amplitude of the positive excitation voltage and the negative excitation voltage based on the leg posture data of the subject under test, when it is determined that the knee joint force is within a first range under the current leg posture of the subject under test; and reduce the amplitude of the positive excitation voltage and the negative excitation voltage when it is determined that the knee joint force is within a second range under the current leg posture of the subject under test.

[0026] In addition, to achieve the above-mentioned purpose, in a second aspect, the present application also provides a method for measuring pressure during knee replacement surgery, which is applied to the pressure measuring device during knee replacement surgery as described above, and the method comprises:

[0027] Detecting the knee joint pressure of the object under test based on an ion-type pressure sensor array, and converting the knee joint pressure into a sensing capacitance signal;

[0028] Converting the sensing capacitance signal generated by the ion-type pressure sensor array into a detection voltage signal, and obtaining a knee joint pressure value based on the detection voltage signal;

[0029] Measuring leg posture data of the subject based on inertial sensor units on the ankles and thighs of the subject;

[0030] The knee joint pressure value and the leg posture data are received, and based on the knee joint pressure value and the leg posture data, knee joint pressure distribution data at different posture angles between the femur and the tibia of the measured object are generated.

[0031] Compared with the prior art, the beneficial effects of this application include:

[0032] On the one hand, the present application can measure high-resolution knee joint pressure values ​​by providing a pressure sensing unit and a signal processing unit. On the other hand, by configuring an inertial sensing unit on the ankle and thigh of the subject, the leg posture data of the subject can be measured in real time. On the other hand, the knee joint pressure value and the leg posture data are transmitted to the electronic device through the receiving unit, and the electronic device can generate knee joint pressure distribution data at different posture angles between the femur and the tibia based on the knee joint pressure value and the leg posture data. This not only improves the accuracy of the knee joint pressure balance measurement at different angles, but also reduces the human risk during the operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0034] Figure 1 is an overall preview schematic diagram of a pressure measurement device in knee replacement surgery according to the first embodiment of the present application;

[0035] Figure 2 is a schematic diagram of the circuit structure of a signal processing unit in a pressure measurement device for knee replacement surgery according to the first embodiment of the present application;

[0036] Figure 3 is a schematic diagram of the principle of a capacitance-voltage conversion circuit in a signal processing unit according to the first embodiment of the present application;

[0037] Figure 4 is a schematic structural diagram of an electronic device in a pressure measurement device during knee replacement surgery according to the first embodiment of the present application;

[0038] Figure 5 is a schematic diagram of the circuit structure of a signal processing unit in a pressure measurement device for knee replacement surgery according to a second embodiment of the present application;

[0039] Figure 6 It is a flow chart of the pressure measurement method in knee replacement surgery according to the first embodiment of the present application.

[0040] Explanation of the accompanying drawings: 10-pressure measurement device during knee replacement surgery; 100-pressure sensing unit; 200-signal processing unit; 210-capacitance-pressure conversion circuit; 220-control unit; 230-multi-way selection unit; 300-inertial sensing unit; 400-receiving unit; 500-electronic device; 501-central processing unit (CPU); 502-read-only memory (ROM); 503-random access memory (RAM); 504-bus; 505-input / output (I / O) interface; 506-input part; 507-output part; 508-storage part; 509-communication part; 510-drive; 511-removable medium. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0042] All terms (including technical and scientific terms) used in this application have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used here should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0043] For example, the terms "first", "second", etc. used in this application may be used in this document to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element.

[0044] For another example, the terms “include”, “comprising”, etc. used in this application indicate the existence of features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0045] As mentioned above, there are devices that can accurately measure the pressure inside and outside the knee joint, but these devices still require the surgeon to manually place the leg in different postures and control the tibia and femur to form different angles to measure the pressure changes of the knee joint at different angles, thereby determining whether the pressure of the knee joint is balanced. However, this method relies on the doctor's adjustment of the leg posture. In actual operation, there may be errors in the angles of the tibia and femur, which in turn affects the accuracy of measuring the pressure balance of the knee joint. The present application proposes a pressure measurement device and measurement method during knee replacement surgery, which realizes the accurate measurement of the pressure of the knee joint at different angles during knee replacement surgery, thereby improving the objectivity and accuracy of intraoperative evaluation.

[0046] Figure 1 FIG. 1 is a schematic diagram showing an overall preview of the pressure measurement device 10 during knee replacement surgery according to the first embodiment of the present application. Figure 1 As shown, the pressure measurement device 10 during knee replacement surgery of this embodiment includes:

[0047] The pressure sensing unit 100 comprises an ion-type pressure sensor array arranged in an array form of m rows and n columns, wherein the ion-type pressure sensor array is used to detect the knee joint pressure of the object under test and convert the knee joint pressure into a sensing capacitance signal, wherein m and n are integers greater than or equal to 1;

[0048] A signal processing unit 200, connected to the ion-type pressure sensor array, for converting the sensing capacitance signal generated by the ion-type pressure sensor array into a detection voltage signal, and obtaining a knee joint pressure value based on the detection voltage signal;

[0049] The inertial sensor units 300 are respectively arranged on the ankles and thighs of the measured object, and are used to measure the leg posture data of the measured object;

[0050] The receiving unit 400 is connected to the electronic device 500 and is used to receive the knee joint pressure value and the leg posture data and transmit the knee joint pressure value and the leg posture data to the electronic device 500;

[0051] The electronic device 500 is used to receive the knee joint pressure value and the leg posture data from the receiving unit 400, and generate knee joint pressure distribution data at different posture angles between the femur and tibia of the object under test based on the knee joint pressure value and the leg posture data.

[0052] The pressure sensing unit 100 and the signal processing unit 200 in the present embodiment are integrated inside the knee joint pressure measuring pad. In knee replacement surgery, the knee joint pressure measuring pad will be inserted into the inside of the knee joint of the subject. When the knee joint pressure measuring pad is inserted into place, the pressure sensing unit 100 uses an ion-type pressure sensor array to detect the pressure distribution inside the knee joint. The ion-type pressure sensor array can convert the pressure signal into a sensing capacitance signal. Subsequently, the signal processing unit 200 electrically connected to the ion-type pressure sensor array is responsible for converting these sensing capacitance signals into detection voltage signals, and measuring the knee joint pressure value based on the detection voltage signal.

[0053] The ion-type pressure sensor array in this embodiment is a group of integrated ion-type pressure sensors. They are arranged in an array form and are used to detect and measure the pressure distribution applied thereto. Each sensor unit can independently detect pressure changes without interfering with each other. This independent detection capability enables the ion-type pressure sensor array to capture pressure changes in various areas inside the knee joint, thereby providing comprehensive pressure distribution information.

[0054] Specifically, the ion-type pressure sensor array includes a flexible ion film dielectric layer and an electrode array layer consisting of m rows and n columns of electrodes. When the pressure inside the knee joint acts on the sensor array, the flexible ion film dielectric layer will deform, causing the capacitance between the electrodes to change, thereby converting the pressure inside the knee joint into a sensing capacitance signal. In this way, the ion-type pressure sensor array can monitor and measure the pressure distribution inside the knee joint in real time, providing important data support for applications such as knee replacement surgery.

[0055] In some embodiments, the driving end of each row of the ion-type pressure sensors in the ion-type pressure sensor array is configured to input an excitation voltage, and the excitation voltage includes a positive excitation voltage and a negative excitation voltage that are input alternately. Figure 2 FIG. 2 is a schematic diagram of the circuit structure of the signal processing unit 200 in the pressure measurement device 10 for knee replacement surgery according to the first embodiment of the present application. Figure 2 As shown, the signal processing unit 200 includes:

[0056] At least one capacitance-to-pressure conversion circuit 210, each of which includes an operational amplifier (OA1-OAn) and a reference capacitor (Cr1-Crn), two ends of the reference capacitor (Cr1-Crn) are respectively connected to the inverting input terminal and the output terminal of the operational amplifier (OA1-OAn), the inverting input terminal of the operational amplifier (OA1-OAn) is configured to be connected to the detection terminal of the ion-type pressure sensor of the corresponding column in the ion-type pressure sensor array; the non-inverting input terminal of the operational amplifier (OA1-OAn) is configured to input a reference voltage, and the output terminal of the operational amplifier (OA1-OAn) is configured to output a first detection voltage and a second detection voltage corresponding to the positive excitation voltage and the negative excitation voltage, respectively, when the driving terminal of the ion-type pressure sensor of the target row in the ion-type pressure sensor array is alternately input with a positive excitation voltage and a negative excitation voltage;

[0057] The control unit 220 is connected to the output end of the operational amplifier (OA1-OAn), and is used to calculate the capacitance value of the ion-type pressure sensor in the target row in the ion-type pressure sensor array based on the amplitudes of the positive excitation voltage and the negative excitation voltage, the first detection voltage and the second detection voltage, and the capacitance value of the reference capacitor (Cr1-Crn), and convert the capacitance value of the ion-type pressure sensor in the target row into the knee joint pressure value of the object under test.

[0058] In this embodiment, the ion-type pressure sensor array includes m rows and n columns of ion-type pressure sensors, where m and n are integers greater than or equal to 1. The m rows and n columns of ion-type pressure sensors can be represented by the first row C11-C1n, the second row C21-C2n, ..., the mth row Cm1-Cmn according to the row; and can be represented by the first column C11-Cm1, the second column C12-Cm2, ..., the nth column C1n-Cmn according to the column. Each ion-type pressure sensor in each row of ion-type pressure sensors in the ion-type pressure sensor array has a driving end and a detection end, wherein the driving end of each row of ion-type pressure sensors is connected to an excitation voltage S1, and the excitation voltage S1 is an alternately input positive excitation voltage and a negative excitation voltage. In one embodiment, the driving end of each row of ion-type pressure sensors inputs the positive excitation voltage and the negative excitation voltage through at least one selection switch (SW1-SWm).

[0059] In this embodiment, each capacitance-pressure conversion circuit 210 includes an operational amplifier (OA1-OAn) and a reference capacitor (Cr1-Crn), and the two ends of the reference capacitor (Cr1-Crn) are respectively connected to the inverting input terminal and the output terminal of the operational amplifier (OA1-OAn), and the inverting input terminal of the operational amplifier (OA1-OAn) is configured to be connected to the detection end of the ion-type pressure sensor of the corresponding column in the ion-type pressure sensor array. For example, for the capacitance-pressure conversion circuit 210 composed of the operational amplifier OA1 and the reference capacitor Cr1, the inverting input terminal of the operational amplifier OA1 is connected to the detection terminal of the first column of ion-type pressure sensors C11-Cm1; for the capacitance-pressure conversion circuit 210 composed of the operational amplifier OA2 and the reference capacitor Cr2, the inverting input terminal of the operational amplifier OA2 is connected to the detection terminal of the second column of ion-type pressure sensors C12-Cm2; and so on, for the capacitance-pressure conversion circuit 210 composed of the operational amplifier OAn and the reference capacitor Crn, the inverting input terminal of the operational amplifier OAn is connected to the detection terminal of the nth column of ion-type pressure sensors C1n-Cmn.

[0060] In this embodiment, in each capacitance-to-pressure conversion circuit 210, a driving voltage S0 is input to the non-phase input terminal of the operational amplifier (OA1-OAn), and the driving voltage S0 is equal to a fixed reference voltage. When the driving terminal of each row of the ion-type pressure sensor is alternately input with a positive excitation voltage and a negative excitation voltage, the output terminal of the operational amplifier (OA1-OAn) can output a first detection voltage and a second detection voltage corresponding to the positive excitation voltage and the negative excitation voltage, respectively, and the first detection voltage and the second detection voltage can be detected by a control unit 220 connected to the output terminal of the operational amplifier (OA1-OAn). The control unit 220 can calculate the capacitance value of the ion-type pressure sensor of the target row in the m-row and n-column ion-type pressure sensor array based on the amplitude of the positive excitation voltage and the negative excitation voltage, the first detection voltage and the second detection voltage, and the capacitance value of the reference capacitor (Cr1-Crn).

[0061] In some embodiments, the control unit 220 may include analog-to-digital conversion (ADC) channels of a number corresponding to the number of columns n of the m-row and n-column ion-type pressure sensor array, and the output end of the operational amplifier (OA1-OAn) corresponding to each column is respectively connected to the corresponding analog-to-digital conversion (ADC) channel. Under the joint action of the driving voltage S0 (i.e., the reference voltage Vref) input to the non-inverting input end of the operational amplifier (OA1-OAn) and the excitation voltage S1 input to the driving end of the ion-type pressure sensor of the target row, the first detection voltage and the second detection voltage output from the output end of the operational amplifier (OA1-OAn) are input to the analog-to-digital conversion (ADC) channel corresponding to the control unit 220, and the capacitance value of each ion-type pressure sensor of the target row is calculated after analog-to-digital conversion.

[0062] The capacitance value calculation principle of the ionization pressure sensor in this embodiment can be combined with Figure 3 It is derived through the following formula. Figure 3 As shown, it is assumed that the capacitance value of the ionization pressure sensor C11 is expressed as , the capacitance value of the reference capacitor Cr1 is expressed as The reference voltage input to the positive input terminal of the operational amplifier OA1 is expressed as Vref, and the amplitude of the positive excitation voltage input to the driving terminal of the ionization pressure sensor C11 is expressed as , the amplitude of the negative excitation voltage is expressed as , the voltage change of the ion-type flexible pressure sensor C11 is expressed as , the capacitance value of the ion-type flexible pressure sensor C11 is expressed as , the voltage change of the reference capacitor Cr1 is expressed as , the charge change of the ionization flexible pressure sensor C11 is expressed as , the charge change of reference capacitor Cr1 is expressed as .

[0063] Since the charge change of the ionization type flexible pressure sensor C11 is basically the same as the charge change of the reference capacitor Cr1, it can be concluded that .

[0064] Then we can get:

[0065] .

[0066] When the driving end of the ionization pressure sensor C11 first changes from the input reference voltage to the input forward excitation voltage for a predetermined time, the input voltage of the driving end of the ionization pressure sensor C11 changes from the reference voltage Vref to At this time, the first detection voltage corresponding to the forward excitation voltage at the output end of the operational amplifier OA1 is expressed as , then we can further get:

[0067] .

[0068] When the driving end of the ionization pressure sensor C11 changes from the input reference voltage to the input negative excitation voltage for a predetermined time, the input voltage of the driving end of the ionization pressure sensor C11 changes from the reference voltage Vref to At this time, the second detection voltage corresponding to the negative excitation voltage at the output terminal of the operational amplifier OA1 is expressed as , then we can further get:

[0069] .

[0070] Subtracting the above two formulas, we can further deduce:

[0071] ;

[0072] Thus, formula (1) can be obtained as follows:

[0073] (1).

[0074] It can be seen that the capacitance value of the ion-type pressure sensor C11 is highly correlated with the ratio of the difference between the first detection voltage and the second detection voltage to the sum of the amplitudes of the positive excitation voltage and the negative excitation voltage, and the capacitance value of the reference capacitor. Therefore, the control unit 220 can calculate the capacitance value of the ion-type pressure sensor in the target row of the m-row and n-column ion-type pressure sensors based on the amplitudes of the positive excitation voltage and the negative excitation voltage, the first detection voltage and the second detection voltage, and the capacitance value of the reference capacitor.

[0075] The sensing calculation method of the ion-type pressure sensor of the control unit 220 can quickly and accurately calculate the capacitance value of the ion-type pressure sensor of the target row based on the amplitudes of the positive excitation voltage and the negative excitation voltage, the difference between the first detection voltage and the second detection voltage, and the capacitance value of the reference capacitor by alternately inputting a positive excitation voltage and a negative excitation voltage into the driving end of the ion-type pressure sensor. This can significantly improve the detection accuracy of the signal processing unit 200 for the ion-type pressure sensor, and meet the needs of high-precision pressure distribution measurement in the knee joint pressure sensing scenario.

[0076] In some embodiments, the signal processing unit 200 is configured to automatically adjust the amplitudes of the positive excitation voltage and the negative excitation voltage according to the leg posture data of the subject to match the sensing accuracy requirements of the knee joint pressure of the subject under different leg postures. This is because, based on the formula described above, , it can be known that the amplitude of the excitation signal is proportional to the amplitude of the first detection voltage and the second detection voltage change. At the same time, there is a positive correlation between the capacitance of the ionization pressure sensor and the force it receives. The greater the force it receives, the greater the capacitance, and the smaller the force, the smaller the capacitance. When it is judged that the knee joint force under the current leg posture of the measured object is in a first range (small range) less than the first threshold, the change of knee joint pressure may be very subtle. By increasing the amplitude of the excitation signal, these subtle changes can be more obviously captured and amplified, thereby improving the measurement accuracy. When it is judged that the knee joint force under the current leg posture of the measured object is in a second range (i.e., a large range) greater than the second threshold, the change of knee joint pressure may be very drastic. If the amplitude of the excitation signal is too large, it may cause the conversion voltage to exceed the processing range of the circuit, thereby causing distortion of the measurement result. By reducing the amplitude of the excitation signal, it can help avoid the overflow of the conversion voltage of the capacitance-pressure conversion circuit 210, thereby maintaining the linearity and accuracy of the measurement and increasing the measurement range. By automatically adjusting the amplitude of the excitation signal, more accurate testing and a wider measurement range can be achieved under different force conditions.

[0077] The inertial sensor unit 300 in this embodiment may be one or more inertial measurement units (IMUs), which are arranged on the ankles and thighs of the measured object and are used to measure the leg posture data of the measured object.

[0078] In some embodiments, the inertial sensing unit 300 includes at least one accelerometer and at least one gyroscope, wherein the accelerometer is used to measure the linear acceleration of the object under test in the directions of three axes in space (usually X, Y, and Z axes), thereby obtaining static posture information to distinguish the user's motion state (such as stillness or leg bending). The gyroscope is used to measure the angular velocity of the object under test in the directions of three axes in space, thereby obtaining dynamic rotation information, that is, the rotation of the femur and tibia of the object under test during the leg bending process, so as to accurately capture the leg posture changes of the object under test. The leg posture data of the object under test is obtained by fusing the static posture information and the dynamic rotation information. In some embodiments, the inertial sensing unit 300 may also include a three-axis magnetometer / barometer for measuring acceleration and angular velocity, etc.

[0079] The receiving unit 400 in this embodiment is communicatively connected to the inertial sensing unit 300 and the signal processing unit 200, respectively, and is used to receive the leg posture data transmitted by the inertial sensing unit 300 and the knee joint pressure value transmitted by the signal processing unit 200 in a wireless communication manner, and transmit the leg posture data and the knee joint pressure value to the electronic device 500 through a wireless communication manner (such as Bluetooth, Wi-Fi, zigbee, etc.), a wired transmission manner (such as a serial port, a USB port, an Ethernet, etc.) or a storage manner (such as a TF card, an SD card, a FLASH storage chip, etc.).

[0080] The electronic device 500 in this embodiment is configured to define the initial leg posture of the subject (a static state with the legs fully extended) as an initial quaternion by integrating the initial leg posture data transmitted by the inertial sensing unit 300 when the device is started. In posture representation, quaternions are usually used to represent rotation from one coordinate system to another coordinate system, which can be expressed as ,in w, x, y, z is a real number, i, j, k is an imaginary unit that satisfies certain multiplication rules, satisfying In some embodiments, the initial leg posture data may also be filtered and denoised before integration to reduce measurement errors.

[0081] Subsequently, the electronic device 500 updates the initial quaternion according to the dynamic rotation information to reflect the leg movement of the object under test. This process can be achieved by integrating the dynamic rotation information, but direct integration will cause drift because the gyroscope inevitably has certain errors. Therefore, the electronic device 500 also needs to correct the updated quaternion according to the static posture information to eliminate the error caused by the gyroscope drift. This is because the acceleration sensor can measure the components of gravity acceleration in the three axes of space, thereby helping to correct the pitch angle and roll angle. The process of updating and correcting this quaternion can be achieved by Kalman filtering or its variants (such as extended Kalman filtering, unscented Kalman filtering, etc.). Kalman filtering is an effective data fusion algorithm that can combine information from different sensors to optimally estimate the state of the system. During the Kalman filtering process, the electronic device 500 constructs a state equation to describe the change of the quaternion over time, and an observation equation to represent the measurement results of the acceleration sensor and the gyroscope. The Kalman filter then iteratively updates its estimate of the quaternion to reflect the latest leg movements while minimizing the bias caused by sensor errors.

[0082] Specifically, in this iterative calculation process, the electronic device 500 needs to use the quaternion estimated in the previous time step and the state equation to predict the quaternion of the current time step. The time step is used to determine the frequency of state equation prediction, that is, how often the state prediction and update are performed. Shorter time steps can provide more frequent updates, but may increase the computational burden, while longer time steps are the opposite. In addition, the noise covariance matrix of the current time step is predicted by using the noise covariance matrix estimated in the previous time step. Next, the Kalman gain is calculated using the predicted noise covariance matrix and the observed noise covariance matrix. Finally, the Kalman gain and static posture information are used to update the leg posture estimate, and the Kalman gain is used to update the noise covariance matrix of the current time step. In each iteration of the Kalman filter, the electronic device 500 reduces the uncertainty of the leg posture data estimation by combining the prediction of the state equation and the observation of the observation equation.

[0083] In some embodiments, the present application can more accurately calculate the posture angle (e.g., pitch angle) between the femur and tibia of the subject by converting the corrected quaternion into a rotation matrix, and calculate the knee joint pressure correction value at different posture angles between the femur and tibia of the subject based on the posture angle and the knee joint pressure value.

[0084] In this embodiment, in the sitting position with the legs fully extended, the pressure between the femur and tibia in the knee joint of the subject reaches the lowest point, and the posture angle between the femur and tibia is exactly 0°. With the natural movement of the tibia, when the angle between the two gradually increases to 90°, that is, in a vertical state, the pressure reaches a peak. In order to quantify the relationship between the pressure of the knee joint and the angle between the femur and tibia, this embodiment regards the movement of the femur as moving in the coordinate system, and the femur is used as the Y-axis to move around the X-axis of the tibia to generate different angles. During the movement, the resultant force in the Y direction measured by the knee joint pressure measurement pad is Fy, and the posture angle between the femur and the tibia measured by the inertial sensor unit 300 is Since the decomposition of force is the reverse process of the composition of force, a force can be decomposed into two or more component forces. In orthogonal decomposition, a force is decomposed into two component forces along the coordinate axis. The calculation formula is as follows:

[0085] ;

[0086] .

[0087] Among them, F represents the resultant force of the pressure on the inside and outside of the knee joint, and Fy is the component of the resultant force F along the y-axis. It is the angle between the femur and tibia, which represents the angle between the resultant force F and the y-axis. This formula describes the resultant force F of the pressure on the inner and outer sides of the knee joint and the angle between the femur and tibia at different bending angles of the knee joint. The relationship between.

[0088] In this embodiment, the electronic device 500 includes one or more processors; a memory, in which one or more programs are stored, wherein when the one or more programs are executed by the one or more processors, the one or more processors execute the steps in the above-mentioned method embodiments.

[0089] In one embodiment, Figure 4 , which shows a schematic diagram of the structure of an electronic device 500 in a pressure measurement device 10 for knee replacement surgery. The electronic device 500 includes a central processing unit (CPU) 501, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 502 or a program loaded from a storage part 508 to a random access memory (RAM) 503. In the RAM 503, various programs and data required for the operation of the electronic device 500 are also stored. The CPU 501, the ROM 502, and the RAM 503 are connected to each other via a bus 504. An input / output (I / O) interface 505 is also connected to the bus 504.

[0090] The following components are connected to the I / O interface 505: an input section 506 including a keyboard, a mouse, etc.; an output section 507 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 508 including a hard disk, etc.; and a communication section 509 including a network interface card such as a LAN card, a modem, etc. The communication section 509 performs communication processing via a network such as the Internet. A drive 510 is also connected to the I / O interface 505 as needed. A removable medium 511, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 510 as needed, so that a computer program read therefrom is installed into the storage section 508 as needed.

[0091] In this embodiment, on the first hand, by providing a pressure sensing unit 100 and a signal processing unit 200, a high-resolution knee joint pressure value can be measured. On the second hand, by configuring an inertial sensing unit 300 on the ankle and thigh of the subject, the leg posture data of the subject can be measured in real time. On the third hand, the knee joint pressure value and the leg posture data are transmitted to the electronic device 500 through the receiving unit 400, and the electronic device 500 can generate knee joint pressure distribution data at different posture angles between the femur and the tibia based on the knee joint pressure value and the leg posture data. This not only improves the accuracy of the knee joint pressure balance measurement at different angles, but also reduces the human risk during the operation.

[0092] Figure 5 is a schematic diagram of the circuit structure of the signal processing unit 200 in the pressure measurement device 10 for knee replacement surgery according to the second embodiment of the present application, as shown in FIG. Figure 5 As shown, the signal processing unit 200 of this embodiment, based on any of the aforementioned implementations, further includes a multi-way selection unit 230, and the multi-way selection unit 230 is used to connect the detection ends of at least one column of the ion-type pressure sensors in the ion-type pressure sensor array to the inverting input end of at least one operational amplifier in sequence.

[0093] In this embodiment, the number a of the capacitive-pressure conversion circuits 210 depends on the number a of the analog-to-digital conversion (ADC) channels of the control unit 220. When the number a of the analog-to-digital conversion (ADC) channels of the control unit 220 is less than the number n of columns of the m-row and n-column ion-type pressure sensors, that is, it is insufficient to meet the detection requirements of all columns of the m-row and n-column ion-type pressure sensors, the detection ends of the n-column ion-type pressure sensors can be connected to the inverting input ends of the corresponding operational amplifiers (OA1-OAa) in a capacitive-pressure conversion circuits 210 in a sequentially selected manner through the multi-way selection unit 230.

[0094] For example, when the number of analog-to-digital conversion (ADC) channels of the control unit 220 is 1, the number of the capacitive-pressure conversion circuit 210 is 1, and the one capacitive-pressure conversion circuit 210 includes an operational amplifier (OA1). At this time, the multiplexer 230 can connect the detection ends of all n columns of ion-type pressure sensors to the inverting input end of the operational amplifier (OA1) of the capacitive-pressure conversion circuit 210 in a sequentially selected manner; when the number of analog-to-digital conversion (ADC) channels of the control unit 220 is 2, the number of the capacitive-pressure conversion circuit 210 is 2, and the two capacitive-pressure conversion circuits 210 include operational amplifiers (OA1, OA2). At this time, the multiplexer 230 can connect all n columns of ion-type pressure sensors to the inverting input end of the operational amplifier (OA1) of the capacitive-pressure conversion circuit 210 in a sequentially selected manner. The detection ends of every two columns of the ion-type pressure sensors in the n columns of ion-type pressure sensors are connected to the inverting input ends of the operational amplifiers (OA1, OA2) of the capacitive-pressure conversion circuit 210 in a sequentially selected manner; similarly, by analogy, when the number of analog-to-digital conversion (ADC) channels of the control unit 220 is a, a is less than n, the number of the capacitive-pressure conversion circuits 210 is a, and the a capacitive-pressure conversion circuits 210 include operational amplifiers (OA1-OAa). At this time, the multiplexing unit 230 can connect the detection ends of every a columns of ion-type pressure sensors in all the n columns of ion-type pressure sensors to the inverting input ends of the operational amplifiers (OA1-OAa) of the capacitive-pressure conversion circuit 210 in a sequentially selected manner.

[0095] It can be understood that when the number of analog-to-digital conversion (ADC) channels of the control unit 220 is n, the number of the capacitive-pressure conversion circuits 210 is n, and the n capacitive-pressure conversion circuits 210 include operational amplifiers (OA1-OAn). At this time, all the paths of the multi-way selection unit 230 are enabled, that is, the detection ends of all n columns of ion-type pressure sensors can be simultaneously connected to the inverting input ends of the operational amplifiers (OA1-OAn) of the n capacitive-pressure conversion circuits 210.

[0096] In this embodiment, through the multi-way selection unit 230, the detection end of at least one column of ion-type pressure sensors can be connected to the inverting input end of at least one operational amplifier (OA1-OAa) in sequence, so that even if the number of analog-to-digital conversion (ADC) channels of the control unit 220 is limited, it can still ensure that the detection requirements of all ion-type pressure sensors are met. In summary, this embodiment can not only effectively utilize limited hardware resources and avoid resource waste, but also ensure the detection accuracy and efficiency of the device. Through the flexible switching and control of the multi-way selection unit 230, efficient management and data collection of the ion-type pressure sensor array are achieved, providing a reliable basis for subsequent data analysis and decision-making.

[0097] Figure 6 FIG. 1 is a flow chart of a method for measuring pressure during knee replacement surgery according to the first embodiment of the present application. Figure 6 As shown, the method for measuring pressure during knee replacement surgery of this embodiment is applied to the device for measuring pressure during knee replacement surgery 10 of the first embodiment or the second embodiment and its subsidiary embodiments, and comprises the following steps:

[0098] Step S10, detecting the knee joint pressure of the object under test based on the ion-type pressure sensor array, and converting the knee joint pressure into a sensing capacitance signal;

[0099] Step S20, converting the sensing capacitance signal generated by the ion-type pressure sensor array into a detection voltage signal, and obtaining a knee joint pressure value based on the detection voltage signal;

[0100] Step S30, measuring the leg posture data of the subject based on the inertial sensor unit 300 on the ankle and thigh of the subject;

[0101] Step S40, receiving the knee joint pressure value and the leg posture data, and generating knee joint pressure distribution data at different posture angles between the femur and tibia of the measured object based on the knee joint pressure value and the leg posture data.

[0102] In summary, the pressure measurement device 10 and method during knee replacement surgery of the embodiment of the present application, on the one hand, can measure high-resolution knee joint pressure values ​​by setting a pressure sensing unit 100 and a signal processing unit 200. On the second hand, by configuring an inertial sensing unit 300 on the ankle and thigh of the subject, the leg posture data of the subject can be measured in real time. On the third hand, the knee joint pressure value and the leg posture data are transmitted to the electronic device 500 through the receiving unit 400, and the electronic device 500 can generate knee joint pressure distribution data at different posture angles between the femur and the tibia based on the knee joint pressure value and the leg posture data. This not only improves the accuracy of the knee joint pressure balance measurement at different angles, but also reduces the human risk during the operation.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0104] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A pressure measurement device during knee replacement surgery, characterized in that: The device comprises: A pressure sensing unit, comprising an ion-type pressure sensor array arranged in an array form of m rows and n columns, the ion-type pressure sensor array is used to detect the knee joint pressure of the object under test and convert the knee joint pressure into a sensing capacitance signal, m and n are integers greater than or equal to 1; A signal processing unit, connected to the ion-type pressure sensor array, for converting the sensing capacitance signal generated by the ion-type pressure sensor array into a detection voltage signal, and obtaining a knee joint pressure value based on the detection voltage signal; Inertial sensor units are respectively arranged on the ankles and thighs of the measured object, and are used to measure the leg posture data of the measured object; a receiving unit, connected to the electronic device, for receiving the knee joint pressure value and the leg posture data and transmitting the knee joint pressure value and the leg posture data to the electronic device; An electronic device, configured to receive the knee joint pressure value and the leg posture data from the receiving unit, and generate knee joint pressure distribution data at different posture angles between the femur and the tibia of the measured object based on the knee joint pressure value and the leg posture data; The driving end of each row of ion-type pressure sensors in the ion-type pressure sensor array is configured to input an excitation voltage, and the excitation voltage includes an alternately input positive excitation voltage and a negative excitation voltage. The signal processing unit is configured to automatically adjust the amplitudes of the positive excitation voltage and the negative excitation voltage according to the leg posture data of the object under test to match the sensing accuracy requirements of the knee joint pressure of the object under test under different leg postures.

2. The pressure measurement device during knee replacement surgery according to claim 1, characterized in that: The inertial sensing unit includes at least one acceleration sensor and at least one gyroscope, which are used to measure the static posture information and dynamic rotation information of the measured object, and fuse the static posture information and the dynamic rotation information to obtain the leg posture data of the measured object.

3. The pressure measurement device during knee replacement surgery according to claim 2, characterized in that: The at least one acceleration sensor is used to measure the linear acceleration of the object under test in the three-axis directions of the spatial coordinate system to obtain the static posture information of the object under test, and the at least one gyroscope is used to measure the angular velocity of the object under test in the three-axis directions of the spatial coordinate system to obtain the dynamic rotation information of the object under test.

4. The pressure measurement device during knee replacement surgery according to claim 2, characterized in that: The electronic device is configured as follows: defining the initial posture of the legs of the measured object as an initial quaternion; updating the initial quaternion according to the dynamic rotation information to reflect the leg movement of the subject; The updated quaternion is corrected according to the static attitude information to eliminate the error caused by the gyroscope drift.

5. The pressure measurement device during knee replacement surgery according to claim 4, characterized in that: The electronic device is also used to convert the corrected quaternion into a rotation matrix to calculate the posture angle between the femur and tibia of the object under test, and calculate the knee joint pressure correction value under different posture angles between the femur and tibia of the object under test based on the posture angle and the knee joint pressure value.

6. The pressure measurement device during knee replacement surgery according to claim 1, characterized in that: The signal processing unit comprises: At least one capacitance-to-pressure conversion circuit, each of which includes an operational amplifier and a reference capacitor, wherein two ends of the reference capacitor are respectively connected to an inverting input terminal and an output terminal of the operational amplifier, wherein the inverting input terminal of the operational amplifier is configured to be connected to a detection terminal of an ion-type pressure sensor of a corresponding column in the ion-type pressure sensor array; the non-inverting input terminal of the operational amplifier is configured to input a reference voltage, and the output terminal of the operational amplifier is configured to output a first detection voltage and a second detection voltage corresponding to the positive excitation voltage and the negative excitation voltage, respectively, when a positive excitation voltage and a negative excitation voltage are alternately input to a driving terminal of an ion-type pressure sensor of a target row in the ion-type pressure sensor array; A control unit is connected to the output end of the operational amplifier, and is used to calculate the capacitance value of the ion-type pressure sensor in the target row in the ion-type pressure sensor array based on the amplitudes of the positive excitation voltage and the negative excitation voltage, the first detection voltage and the second detection voltage, and the capacitance value of the reference capacitor, and convert the capacitance value of the ion-type pressure sensor in the target row into the knee joint pressure value.

7. The pressure measurement device during knee replacement surgery according to claim 6, characterized in that: The signal processing unit further comprises a multi-way selection unit, which is used to sequentially connect the detection ends of at least one column of the ion-type pressure sensors in the ion-type pressure sensor array to the inverting input end of at least one operational amplifier.

8. The pressure measurement device during knee replacement surgery according to claim 6, characterized in that: The signal processing unit is configured to increase the amplitude of the positive excitation voltage and the negative excitation voltage based on the leg posture data of the object under test, when it is determined that the knee joint force is within the first range under the current leg posture of the object under test; and reduce the amplitude of the positive excitation voltage and the negative excitation voltage when it is determined that the knee joint force is within the second range under the current leg posture of the object under test.

9. A method for measuring pressure during knee replacement surgery, applied to the device for measuring pressure during knee replacement surgery as claimed in any one of claims 1 to 8, characterized in that: include: Detecting the knee joint pressure of the object under test based on an ion-type pressure sensor array, and converting the knee joint pressure into a sensing capacitance signal; Converting the sensing capacitance signal generated by the ion-type pressure sensor array into a detection voltage signal, and obtaining a knee joint pressure value based on the detection voltage signal; Measuring leg posture data of the subject based on inertial sensor units on the ankles and thighs of the subject; The knee joint pressure value and the leg posture data are received, and based on the knee joint pressure value and the leg posture data, knee joint pressure distribution data at different posture angles between the femur and the tibia of the measured object are generated.

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