A kinematic monitoring method for post-hip arthroplasty rehabilitation

Abstract

The application discloses a kind of kinematics monitoring methods for hip replacement post-rehabilitation, it is related to kinematics monitoring technical field;Including the following steps: monitoring element arrangement, IMU sensor group is arranged hip joint and thigh, and power module, processor and bluetooth communication module are worn on human body;Data acquisition, IMU sensor group gathers the vector data of hip joint and thigh, and is passed to processor, and processor passes data to PC end by bluetooth communication module, PC end simultaneously calculates the quaternion of hip bone angle and leg bone angle quaternion, then subtracts to obtain relative included angle quaternion, calibration, selects multiple standard poses in hip replacement post-rehabilitation evaluation as calibration reference.The application designs corresponding monitoring scheme based on multiple IMU sensors and forms software and hardware system, realizes the real-time measurement and calculation to the hip joint angle of patient, assists doctor to evaluate and guide the postoperative rehabilitation movement intensity of patient.

Description

Technical Field

[0001] This invention relates to the field of kinematic monitoring technology, and in particular to a kinematic monitoring method for rehabilitation after hip replacement surgery. Background Technology

[0002] The hip joint is the most important large joint connecting the trunk and lower limbs for stability. Once diseased, it will seriously affect the patient's health and quality of life. The risk of complications after hip replacement surgery is becoming increasingly serious. Dislocation is one of the most common and costly, mostly occurring within the first 3 months after surgery. Statistics show that the incidence of dislocation after primary hip replacement surgery is 0.2%-7% when patients follow postoperative rehabilitation guidelines, but it can increase to 10%-25% after revision hip replacement surgery. More than 60% of dislocation patients have a history of multiple dislocations, often requiring reoperation for closed or even open reduction, and more than 50% of dislocation patients require a second revision surgery. Developing kinematic monitoring technology and supporting wearable hardware and software devices for postoperative hip replacement surgery can enable real-time monitoring and perception of hip joint movement during postoperative rehabilitation, assisting doctors in assessing and guiding the intensity of postoperative rehabilitation exercises, making the postoperative transition smoother, reducing complications, improving rehabilitation outcomes, and empowering orthopedic postoperative rehabilitation, which has significant clinical application value.

[0003] Therefore, this invention proposes a kinematic monitoring method for post-hip replacement surgery rehabilitation. Summary of the Invention The purpose of this invention is to address the shortcomings of existing technologies by proposing a kinematic monitoring method for post-hip replacement surgery rehabilitation.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A kinematic monitoring method for rehabilitation after hip replacement surgery includes the following steps: S1: Monitoring element placement: The IMU sensor group is placed at the hip joint and thigh, and the power module, processor and Bluetooth communication module are worn on the human body. S2: Data acquisition. The IMU sensor group acquires vector data of the hip joint and thigh and transmits it to the processor. The processor transmits the data to the PC via the Bluetooth communication module. The PC simultaneously calculates the hip bone angle quadruple and the leg bone angle quadruple, and then subtracts them to obtain the relative angle quadruple. S3: Calibration. Select multiple standard postures in the postoperative rehabilitation assessment of hip replacement surgery as calibration benchmarks. Then, have the monitored subject maintain each standard posture in turn, and collect the relative angle quadruples data simultaneously. Then, establish a calculation model. S4: Define the constraints and establish constraints on the computational model; S5: Result calculation, calculates the angle of the hip joint based on real-time monitored sensor data.

[0005] Preferably, the IMU sensor group in step S1 includes an accelerometer, a gyroscope, and a magnetometer.

[0006] Preferably, the IMU sensor group is configured in six groups, of which four groups of IMU sensors are respectively located on the bilateral anterior superior iliac spines and bilateral posterior superior iliac spines, and the four groups of IMU sensors are arranged in an elliptical shape along the same hip joint circumference, and the other two groups of IMU sensors are respectively located on the lateral thigh and the anterior thigh, and the line connecting them is perpendicular to the direction of the leg bone.

[0007] Preferably, the multiple sets of IMU sensors use the same coordinate system, that is, their X-axis, Y-axis and Z-axis are all parallel.

[0008] Preferably, the multiple sets of IMU sensors use the same coordinate system, that is, their X-axis, Y-axis and Z-axis are all parallel, with the Y-axis pointing upward, the X-axis pointing to the right and the Z-axis pointing forward.

[0009] Preferably, in step S2, the calculation method for the relative angle quadruple includes the following steps: S21: According to the formula Calculate the hip angle quaternion , Let m be the quadruplet vector of the i-th sensor located at the hip bone, where m represents the total number of sensors located at the hip bone. S22: According to the formula Calculate the leg bone angle quaternion , Let n be the quadruplet vector of the j-th sensor located on the leg bone, where n represents the total number of sensors located on the hip bone. S23: Then, subtract the hip angle quaternion from the bone angle quaternion to obtain the relative angle quaternion. , It is represented as: ,in As a scalar, It is a three-axis vector.

[0010] Preferably, in step S3, the standard pose includes: Standing position: The patient stands naturally with both lower limbs extended and the hip joint in a neutral position. At this time, the corresponding hip joint angles are flexion angle 0°, adduction and abduction angle 0°, and rotation angle 0°. Sitting upright: The patient sits upright in a chair with their thighs perpendicular to their torso. At this position, the corresponding hip joint angles are 90° flexion, 0° adduction / abduction, and 0° rotation. Left-side seated position: The patient sits upright in a chair with the thighs turned to the left at a 30° angle to the torso. The corresponding hip joint angles are 90° flexion, 0° adduction / abduction, and 30° rotation. Right-side sitting position: The patient sits upright in a chair with the thighs turned to the right at a 30° angle to the torso. At this position, the corresponding hip joint angles are 90° flexion, 0° adduction and abduction, and -30° rotation. Supine position: The patient lies flat with both lower limbs naturally extended, and the hip joint position is the same as in the standing position. At this time, the corresponding hip joint angles are flexion 0°, adduction and abduction 0°, and rotation 0°.

[0011] Preferably, in step S3, the model is: ,in These represent the buckling angle, adduction / abduction angle, and rotation angle, respectively. k and b are the regression coefficient and bias term, respectively. k and b are obtained from the sample data using standard pose data. calculate.

[0012] Preferably, in step S4, the constraint condition is: .

[0013] The beneficial effects of this invention are as follows: This invention designs a corresponding monitoring scheme based on multiple IMU sensors and forms a hardware and software system to realize real-time measurement and calculation of the patient's hip joint angle, assisting doctors in assessing and guiding the intensity of the patient's postoperative rehabilitation exercises. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the deployment scheme of hip joint kinematic monitoring sensors for a kinematic monitoring method for post-hip replacement surgery rehabilitation proposed in this invention; wherein, Figure A is the front view; Figure B is the rear view; and Figure C is the side view. Figure 2 This is a circuit diagram showing the connection between the sensor and processor in a kinematic monitoring method for post-hip replacement surgery rehabilitation proposed in this invention. Figure 3 This is a logic diagram of the data transfer control program for a kinematic monitoring method for post-hip replacement surgery rehabilitation proposed in this invention. Figure 4 This is a circuit diagram of a Bluetooth wireless transmission module for a kinematic monitoring method for post-hip replacement surgery rehabilitation proposed in this invention. Figure 5 This is a circuit diagram of a centralized power supply module for a kinematic monitoring method for post-hip replacement surgery rehabilitation proposed in this invention. Detailed Implementation

[0015] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0016] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0017] Example 1: This invention utilizes a measurement array composed of multiple IMU inertial sensors to perform real-time measurement of hip joint angles. The IMU inertial sensor consists of an accelerometer, a gyroscope, and a magnetometer. Through the mutual complementation of the measurement results from these three components, it can provide omnidirectional motion state measurements such as acceleration, angular velocity, and magnetic flight angle. This invention primarily utilizes the magnetic flight angle measurement function of the IMU sensors. The sensing and measurement system of this invention uses a measurement array composed of six IMU inertial sensors for measurement. Taking the left hip joint as an example, this invention will proceed as follows... Figure 1 The proposed solution involves sensor deployment.

[0018] A kinematic monitoring method for rehabilitation after hip replacement surgery is as follows: 1. This invention will be carried out in accordance with the following... Figure 1 The proposed method involves placing IMU sensors (numbers 1 to 4) at four bony landmarks on the patient's body surface, corresponding to the bilateral anterior superior iliac spines and bilateral posterior superior iliac spines. The elliptical plane formed by these four bony landmarks effectively reflects the pelvic angle, and since these landmarks are located at the points where bones are closest to the skin, placing the IMU sensors here reduces the influence of muscle tissue on pelvic angle measurements during movement.

[0019] 2. This invention will also deploy IMU sensors No. 5 and No. 6 on the thigh. IMU sensor No. 5 is located at the front of the left thigh, and sensor No. 6 is located on the outer side of the left thigh (left side), without affecting the patient's movement. The vertical position of sensors No. 5 and No. 6 can be adjusted as needed, but their plane must be perpendicular to the leg bone to ensure that sensors No. 5 and No. 6 can effectively measure the leg movement angle.

[0020] 3. The above six IMU sensors use a consistent coordinate system during deployment. For Figure 1 In Figure A (front view), all IMU sensors are positioned with the y-axis pointing upwards, the x-axis to the right, and the z-axis forward. For Figure 1 The coordinate systems indicated in Figure B (rear view) and Figure C (side view) are also consistent with this. This allows for the processing of angles measured by the six IMU sensors within the same coordinate system without the need for complex coordinate transformations.

[0021] 4. Each IMU sensor measures angles in the form of a quadruplet. To reduce the influence of angle errors during IMU sensor deployment and their own measurement errors, this invention uses the average angle measurement value of the quadruplet of IMU sensors No. 1 to No. 4 in the waist as the pelvic angle measurement value, and uses the average angle measurement value of the quadruplet of IMU sensors No. 5 and No. 6 in the leg as the leg bone angle measurement value.

[0022] Figure 1 This is a kinematic monitoring deployment scheme using the left hip joint as an example. For the right hip joint, the sensor deployment scheme is similar: the positions of IMU sensors 1 through 4 in the lumbar region remain unchanged, and all six IMU sensors maintain an upward y-axis, a rightward x-axis, and an forward z-axis. Figure 1 The solutions shown are all consistent. The only difference is that IMU sensor #5 is placed directly in front of the right thigh, while IMU sensor #6 is placed on the outside (right side) of the left thigh. This difference in the deployment of the left / right hip joint monitoring sensors will not affect the subsequent device implementation or angle calculation.

[0023] Sensor data relay implementation as follows Figure 2 As shown in the diagram, in the sensor data transfer circuit, the sensor's input and output interfaces are connected to the central processing unit's interface using a network tag interface, and a 5V power supply is provided to the sensor. TX8 is the input terminal for sensor 8 data, and RX8 is the output terminal for sensor 8 data. After connection, data transmission between the sensor and the processor can be achieved. Other sensor circuits are similar.

[0024] The sensor's input / output interface is connected to the processor's serial port via a circuit. The communication through this serial port is controlled by setting the state of registers on the program side, thus controlling the sensor. The specific data transfer control program logic is as follows: Figure 3 As shown in the diagram. The specific data relay protocol is as follows: The sensors report 8-byte data frames via serial port. Each sensor is assigned an ID number, and then the reported data from all sensors are grouped into packets for backend processing. The start byte of the data packet is 0xAAAA, and the end byte is 0x4D4D. The sensor ID number follows the start byte, followed by the data reported by that sensor.

[0025] The circuit of the Bluetooth wireless data transmission module is as follows: Figure 4 As shown, the input and output interfaces of the Bluetooth module are connected to the interface of the central processing unit using a network tag interface, and a 5V power supply is provided to the sensor. TX5 is the input terminal of the Bluetooth module, and RX8 is the output terminal of the Bluetooth module. After connection, data transmission between the Bluetooth module and the processor can be realized. Then, a Bluetooth connection is made on the PC to realize communication between the hardware and the PC.

[0026] The circuit diagram of the centralized power supply module for each IMU sensor, central processing unit, Bluetooth transmission module and other electronic components is as follows: Figure 5 As shown, this centralized power supply module uses a single port to input the total voltage, which is then divided into 5V and 3.3V by a voltage regulator module. Another voltage regulator module then divides the 5V into 1.5V. The 5V powers the sensors, the 3.3V powers the processor and Bluetooth module, and the 1.5V powers other electronic components.

[0027] For the monitoring data measured using the aforementioned equipment and received in real time via Bluetooth, the hip joint angle can be calculated as follows. Let the quadruplet vectors measured by sensors 1 to 4 at each time point be V1, V2, V3, and V4, and the quadruplet vectors measured by sensors 5 and 6 be V5 and V6. This invention first parses the obtained data to obtain the quadruplet for each sensor, and then averages the quadruplets from the four sensors on the hip joint to obtain the hip angle quadruplet: (1) Then, the quaternion vectors from sensors 5 and 6 on the thigh are averaged to obtain the leg bone angle quaternion: (2) The vector subtraction of the hip bone angle quaternion and the leg bone angle quaternion yields the vector estimate of the relative hip joint angle quaternion: (3) The above calculation uses a concise quadruplet vector to represent the three-dimensional pose, denoted as the relative angle quadruplet Q = (q0, q1, q2, q3), where q0 is the scalar part and q1, q2, q3 are the vector parts. However, in clinical applications, it needs to be converted to the intuitive Euler angles (hip joint angles). Considering the characteristics of hip joint movement (mainly involving flexion, adduction / abduction, and rotation), Euler angles are calculated using the ZYX rotation sequence (first rotating around the Z-axis, then around the Y-axis, and finally around the X-axis), with the corresponding angle definitions as follows: Around the Z-axis (anteroposterior direction): Hip joint rotation angle ( ); Around the Y-axis (vertical direction): Hip adduction and abduction angle ( ); Around the X-axis (left-right direction): Hip flexion angle ( ).

[0028] Meanwhile, to eliminate the influence of inherent sensor errors, deployment deviations, and individual human differences on the measurement results, it is necessary to calibrate the relative angle quadruple based on standard poses. Five standard poses commonly used in post-hip replacement rehabilitation assessments are selected as calibration benchmarks: Standing position: The patient stands naturally with both lower limbs extended and the hip joint in a neutral position. At this time, the corresponding hip joint angles are flexion angle 0°, adduction and abduction angle 0°, and rotation angle 0°. Sitting upright: The patient sits upright in a chair with their thighs perpendicular to their torso. At this position, the corresponding hip joint angles are 90° flexion, 0° adduction / abduction, and 0° rotation. Left-side seated position: The patient sits upright in a chair with the thighs turned to the left at a 30° angle to the torso. The corresponding hip joint angles are 90° flexion, 0° adduction / abduction, and 30° rotation. Right-side sitting position: The patient sits upright in a chair with the thighs turned to the right at a 30° angle to the torso. At this position, the corresponding hip joint angles are 90° flexion, 0° adduction and abduction, and -30° rotation. Supine position: The patient lies flat with both lower limbs naturally extended, and the hip joint position is the same as in the standing position. At this time, the corresponding hip joint angles are flexion 0°, adduction and abduction 0°, and rotation 0°. By having the patient wear the measuring device of this invention and then hold the above five standard poses sequentially for 1 to 2 seconds, the measurement results of each IMU sensor during the measurement period are obtained using the measuring device. The relative angle quadruplets under the five standard poses are denoted as Q1, Q2, Q3, Q4, and Q5, and the flexion angles under each pose are also known. Inward and outward angles Rotation angle Therefore, we can obtain the following 5 sample data: (4) Theoretical analysis shows that the buckling angle Inward and outward angles Rotation angle The components of the relative angle quadruple Q = (q0, q1, q2, q3) maintain a linear relationship, that is: (5) In equation (5), kij is the regression coefficient and bi is the bias term. Based on the measurement results of the five standard poses in equation (4), five sample data were constructed, with the four components q0, q1, q2, and q3 of the quadruple as independent variables, and the three angles of the hip joint (flexion angle) as independent variables. Inward and outward angles Rotation angle Using q0, q1, q2, q3 as the dependent variable, the required regression coefficients kij and bi are determined by a linear regression algorithm. For the sensor data measured in real time, the corresponding relative angle quadruple Q = (q0, q1, q2, q3) can be obtained first by following the calculation methods in equations (1) to (3), and then substituted into equation (5) determined by linear regression to calculate the corresponding buckling angle. Inward and outward angles Rotation angle Finally, the calculated Euler angles are constrained to a range of -120° to 60°, adduction and abduction angles of -45° to 45°, and rotation angles of -45° to 45°. Abnormal values ​​that exceed the physiological range of motion are removed, and the accurate hip joint angles are finally output.

[0029] This invention designs a corresponding monitoring scheme based on multiple IMU sensors and forms a hardware and software system to realize real-time measurement and calculation of the patient's hip joint angle, assisting doctors in assessing and guiding the intensity of the patient's postoperative rehabilitation exercises.

[0030] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A kinematic monitoring method for rehabilitation after hip replacement surgery, characterized in that, Includes the following steps: S1: Monitoring element placement: The IMU sensor group is placed on the surface of the hip joint and thigh, and the power module, processor and Bluetooth communication module are worn on the human body. S2: Data acquisition. The IMU sensor group acquires vector data of the hip joint and thigh and transmits it to the processor. The processor transmits the data to the PC via the Bluetooth communication module. The PC simultaneously calculates the hip bone angle quadruple and the leg bone angle quadruple, and then subtracts them to obtain the relative angle quadruple. The calculation method for the relative included angle quadruple includes the following steps: S21: According to the formula Calculate the hip angle quaternion , Let m be the quadruplet vector of the i-th sensor located at the hip bone, where m represents the total number of sensors located at the hip bone. S22: According to the formula Calculate the leg bone angle quaternion , Let n be the quadruplet vector of the j-th sensor located on the leg bone, where n represents the total number of sensors located on the leg bone. S23: Then, subtract the hip angle quaternion from the leg angle quaternion to obtain the relative angle quaternion. , It is represented as: ,in As a scalar, It is a three-axis vector; S3: Calibration. Select multiple standard postures in the postoperative rehabilitation assessment of hip replacement surgery as calibration benchmarks. Then, have the monitored subject maintain each standard posture in turn, and collect the relative angle quadruples data simultaneously. Then, establish a calculation model. The standard pose includes: Standing position: The patient stands naturally with both lower limbs extended and the hip joint in a neutral position; at this time, the corresponding hip joint position angles are flexion angle 0°, adduction and abduction angle 0°, and rotation angle 0°. Sitting position: The patient sits upright in a chair with his thighs perpendicular to his torso; at this time, the corresponding hip joint angles are 90° flexion, 0° adduction and abduction, and 0° rotation. Left-side sitting position: The patient sits upright in a chair with the thighs turned to the left at a 30° angle to the torso; at this time, the corresponding hip joint position angles are 90° flexion, 0° adduction and abduction, and 30° rotation. Right-side sitting position: The patient sits upright in a chair with the thighs turned to the right at a 30° angle to the torso; at this time, the corresponding hip joint position angles are flexion angle 90°, adduction and abduction angle 0°, and rotation angle -30°. Supine position: The patient lies flat with both lower limbs naturally extended, and the hip joint position is the same as in the standing position; at this time, the corresponding hip joint position angles are flexion angle 0°, adduction and abduction angle 0°, and rotation angle 0°. The calculation model is as follows: ,in These are the buckling angle, the adduction / abduction angle, and the rotation angle, respectively. and These are the regression coefficients and the bias term, respectively. and Sample data was obtained from standard pose data. The calculation specifically involves the four components of the quaternion. , , , As independent variables, the three angles of the hip joint are used. The dependent variable is determined through calculation using a linear regression algorithm; S4: Define the constraints and establish constraints on the computational model; S5: Result calculation, calculates the angle of the hip joint based on real-time monitored sensor data.

2. The kinematic monitoring method for post-hip replacement surgery rehabilitation according to claim 1, characterized in that, The IMU sensor group in step S1 includes an accelerometer, a gyroscope, and a magnetometer.

3. The kinematic monitoring method for post-hip replacement surgery rehabilitation according to claim 1, characterized in that, The IMU sensor group consists of six sets, with four sets of IMU sensors located on the bilateral anterior superior iliac spines and bilateral posterior superior iliac spines, respectively, and arranged along the same hip joint circumference. The other two sets of IMU sensors are located on the lateral thigh and the anterior thigh, respectively, and the line connecting them is perpendicular to the direction of the leg bone.

4. The kinematic monitoring method for post-hip replacement surgery rehabilitation according to claim 2, characterized in that, The multiple sets of IMU sensors use the same coordinate system, that is, their X-axis, Y-axis and Z-axis are all parallel.

5. A kinematic monitoring method for post-hip replacement surgery rehabilitation according to claim 2, characterized in that, The multiple sets of IMU sensors use the same coordinate system, that is, their X-axis, Y-axis and Z-axis are all parallel, with the Y-axis pointing upwards, the X-axis pointing to the right and the Z-axis pointing forwards.

6. The kinematic monitoring method for post-hip replacement surgery rehabilitation according to claim 1, characterized in that, In step S4, the constraints are as follows: .

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