Wearable angle monitoring system for knee joint rehabilitation training after knee joint replacement

Abstract

The invention provides a wearable knee joint rehabilitation training angle monitoring system after knee joint replacement, and the system comprises a wearable monitoring unit, a CPM machine adaption unit, a cloud data management unit, and a multi-terminal display unit, and is provided with a wearable inertial sensing module, a CPM machine adaption module, a cloud data processing module, and a multi-terminal display module. And integration of cooperative monitoring and autonomous monitoring of the CPM is realized. The system can be in butt joint with an existing CPM, the knee joint angle is calculated through the nine-axis IMU in combination with the self-adaptive Kalman filtering algorithm, and when the deviation exceeds a threshold value, the stroke of the CPM is automatically and finely adjusted; angle monitoring and action early warning can be independently realized in the mode, and the training data synchronization cloud supports remote evaluation. The knee joint rehabilitation training device is compatible with existing equipment, light and wearable, solves the problem of out-of-hospital fault of knee joint rehabilitation training, improves rehabilitation safety and individuation degree, and is suitable for orthopedic postoperative clinical rehabilitation scenes.

Description

Technical Field

[0001] This invention relates to the field of medical rehabilitation equipment technology, and more specifically, to a wearable knee joint rehabilitation training angle monitoring system after knee replacement surgery. Background Technology

[0002] Knee replacement surgery is the core treatment for end-stage knee joint diseases such as severe osteoarthritis and rheumatoid arthritis. Early continuous passive motion (CPM) training after surgery is a key step in preventing joint adhesions and restoring joint mobility.

[0003] Currently, most mainstream clinical CPM machines are bedside fixed structures that rely on mechanical push rods to drive the knee joint to complete flexion and extension movements, which have the following prominent drawbacks: Traditional CPM machines typically weigh over 20kg and require fixed installation beside the hospital bed, limiting patients to training within the ward. This fails to meet the needs of patients for continued rehabilitation after discharge, leading to a gap in outpatient rehabilitation training. Furthermore, traditional CPM machines can only preset motion angles based on mechanical travel, unable to detect actual angle deviations caused by limb displacement and changes in muscle tension in real time.

[0004] Traditional CPM machines cannot automatically record key data such as training angle and duration. Patients lack professional angle monitoring methods when training independently, and medical staff cannot grasp the progress of rehabilitation outside the hospital, making it difficult to dynamically adjust the rehabilitation plan.

[0005] Therefore, a knee joint angle monitoring system that is compatible with existing clinical CPM machines and is wearable and lightweight is needed to achieve a closed loop of accurate angle verification for CPM machine training and angle monitoring for out-of-hospital self-training. Therefore, a wearable knee joint rehabilitation training angle monitoring system after knee replacement surgery is proposed. Summary of the Invention

[0006] The purpose of this invention is to address the problems raised in the existing background technology. To achieve the above-mentioned objective, this invention provides the following technical solution: a wearable knee joint rehabilitation training angle monitoring system after knee replacement surgery, comprising a wearable monitoring unit, a CPM machine adapter unit, a cloud data management unit, and a multi-terminal display unit; the wearable monitoring unit includes a first strap adapted to the thigh segment, a second strap adapted to the calf segment, and nine-axis inertial measurement units respectively disposed on the two straps; The CPM machine adapter unit is used to connect the wearable monitoring unit with the existing clinical CPM machine to enable fine-tuning of data and parameters; the cloud data management unit is used to receive, store and process monitoring data and generate rehabilitation assessment reports; the multi-terminal display unit is used to display real-time angle data and rehabilitation assessment results to medical staff and patients.

[0007] As a preferred technical solution of the present invention, the first and second straps of the wearable monitoring unit are made of high-elastic nylon fabric, with built-in anti-slip silicone strips, and the tightness can be adjusted by Velcro. The fit range is from 40cm to 70cm, and the overall weight does not exceed 50g.

[0008] As a preferred technical solution of the present invention, the nine-axis inertial measurement unit integrates a three-axis accelerometer, a three-axis gyroscope and a three-axis magnetometer, and is installed in the lateral condyle region of the knee joint. It uses an adaptive Kalman filter algorithm to fuse the original sensor data, and the knee joint angle calculation accuracy is within ±1.5°.

[0009] As a preferred technical solution of the present invention, the CPM machine adapter unit includes a wired adapter module and a wireless module: The wired adapter module is equipped with multi-specification adapter cables, which are compatible with mainstream CPM machine control ports such as RS232 and TTL. It can read the preset training parameters of the CPM machine and send angle fine-tuning commands. The wireless module has a built-in Bluetooth gateway, which can synchronize monitoring data to the CPM machine's display terminal, allowing medical staff to manually adjust the CPM machine parameters.

[0010] As a preferred technical solution of the present invention, when the actual knee joint angle measured by the wearable monitoring unit deviates from the preset angle of the CPM machine by ≥5°, the CPM machine adapter unit automatically sends a stroke adjustment command to the CPM machine to correct the displacement of the mechanical push rod of the CPM machine, so that the actual angle returns to the preset range.

[0011] As a preferred technical solution of the present invention, the cloud data management unit has a built-in clinical knee replacement surgery rehabilitation target database, which can automatically compare the rehabilitation standards at the same stage based on the patient's training angle data, and generate a rehabilitation assessment report including the angle achievement rate, the trend of the maximum flexion angle, and risk warning.

[0012] As a preferred technical solution of the present invention, the medical workstation supports real-time viewing of the patient's training angle curve, retrieval of historical rehabilitation reports, and push of personalized rehabilitation plans to the patient's mobile device via the cloud.

[0013] As a preferred technical solution of the present invention, the wearable monitoring unit has a built-in low-power Bluetooth module, a continuous working time of ≥8 hours, supports Type-C fast charging, and a 30-minute charge can meet the training and monitoring needs of 4 hours.

[0014] As a preferred technical solution of the present invention, the cloud data management unit uses the MQTT protocol to realize data transmission, encrypts and stores patient data, and associates it with the patient's unique identity ID, which complies with medical data privacy protection standards.

[0015] As a preferred technical solution of the present invention, it has two modes: CPM machine collaborative training and autonomous training. The system works in conjunction with the CPM machine to achieve automatic angle calibration and parameter fine-tuning; The wearable monitoring unit works independently, and training data is automatically uploaded to the cloud, allowing medical staff to remotely view and adjust the treatment plan.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: The wearable monitoring unit of this invention weighs less than 50g, is comfortable to wear and does not restrict daily activities, solving the pain point that traditional CPM machines cannot be used, and enabling seamless out-of-hospital rehabilitation training. This invention achieves high-precision angle calculation through an adaptive Kalman filter algorithm, effectively correcting mechanical travel errors of the CPM machine and movement deviations during autonomous training, avoiding joint adhesions or secondary injuries caused by improper angles. This invention achieves unified storage and analysis of out-of-hospital rehabilitation data through a cloud-based data management unit, providing medical staff with full-cycle rehabilitation data support, facilitating the development of dynamic and personalized rehabilitation plans. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall system architecture provided by the present invention; Figure 2 This is a schematic diagram showing the detailed parameters of the wearable monitoring unit provided by the present invention; Figure 3 This is a schematic diagram of the cloud data management unit provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention.

[0019] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features and technical solutions in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0020] Example 1: A wearable knee joint rehabilitation training angle monitoring system after knee replacement surgery, including a wearable monitoring unit, a CPM machine adapter unit, a cloud data management unit and a multi-terminal display unit: The wearable monitoring unit includes a first strap adapted to the thigh segment, a second strap adapted to the calf segment, and a nine-axis inertial measurement unit respectively set on the two straps. The CPM machine adapter unit connects the wearable monitoring unit to existing clinical CPM machines to enable fine-tuning of data and parameters; the cloud data management unit receives, stores, and processes monitoring data to generate rehabilitation assessment reports; and the multi-terminal display unit displays real-time angle data and rehabilitation assessment results to medical staff and patients.

[0021] The first and second straps of the wearable monitoring unit are made of high-elastic nylon fabric, with built-in anti-slip silicone strips. The tightness can be adjusted by Velcro, and it can fit leg circumferences of 40cm to 70cm. The overall weight does not exceed 50g.

[0022] The nine-axis inertial measurement unit integrates a three-axis accelerometer, a three-axis gyroscope, and a three-axis magnetometer. The installation position corresponds to the lateral condyle region of the knee joint. It uses an adaptive Kalman filter algorithm to fuse the original sensor data, and the knee joint angle calculation accuracy is within ±1.5°.

[0023] The CPM adapter unit includes a wired adapter module and a wireless module: The wired adapter module is equipped with multi-specification adapter cables, compatible with mainstream CPM machine control ports such as RS232 and TTL, and can read preset training parameters of the CPM machine and send angle fine-tuning commands. The wireless module has a built-in Bluetooth gateway, which can synchronize monitoring data to the CPM machine's display terminal, allowing medical staff to manually adjust the CPM machine parameters.

[0024] When the measured knee joint angle by the wearable monitoring unit deviates from the preset angle of the CPM machine by ≥5°, the CPM machine adapter unit automatically sends a stroke adjustment command to the CPM machine to correct the displacement of the mechanical push rod of the CPM machine, so that the actual angle returns to the preset range.

[0025] The cloud-based data management unit has a built-in database of rehabilitation goals after clinical knee replacement surgery. Based on the patient's training angle data, it can automatically compare with the rehabilitation standards at the same stage and generate rehabilitation assessment reports that include the angle achievement rate, the trend of the maximum flexion angle, and risk warnings.

[0026] The medical workstation supports real-time viewing of patients' training angle curves, retrieval of historical rehabilitation reports, and push of personalized rehabilitation plans to patients' mobile devices via the cloud. The wearable monitoring unit has a built-in low-power Bluetooth module, with a continuous working time of ≥8 hours. It supports Type-C fast charging, and a 30-minute charge can meet the training and monitoring needs for 4 hours.

[0027] The cloud-based data management unit uses the MQTT protocol to transmit data, encrypts and stores patient data, and associates it with the patient's unique identity ID, which complies with medical data privacy protection standards.

[0028] This invention system, based on inertial attitude sensing technology, multi-device technology, and cloud data analysis technology, achieves integrated knee joint rehabilitation angle management through CPM machine collaborative monitoring and autonomous monitoring. The specific working principle is as follows: The patient secures the wearable monitoring unit's thigh strap to the upper third of the thigh and the calf strap to the upper third of the calf, ensuring that both nine-axis inertial measurement units (IMUs) are aligned with the lateral condyle of the knee joint and within the same sagittal plane. Upon system startup, the system automatically enters a zero-position calibration process, guiding the patient to maintain full knee extension (0°) for 3 seconds. During this time, the system records the initial posture data of the thigh and calf IMUs, serving as the reference coordinate system for subsequent angle calculations and compensating for initial angle errors caused by wear position deviations.

[0029] Two IMUs simultaneously acquire raw data during the motion process: Triaxial accelerometer: Collects linear acceleration changes in the thigh and calf to identify the direction and amplitude of limb movements; Three-axis gyroscope: collects the angular velocity of limb rotation, captures the dynamic angle changes during the flexion and extension of the knee joint in real time, and compensates for the angle drift of the accelerometer in a static state; Three-axis magnetometer: senses the Earth's magnetic field, helps correct the cumulative errors caused by the long-term operation of the gyroscope, and stabilizes the coordinate system reference.

[0030] The acquisition frequency was set to 100Hz to ensure complete capture of detailed data on rapid knee flexion and extension movements.

[0031] Parameter synchronization: The CPM machine adapter unit reads the preset training parameters (including flexion and extension angle range, exercise cycle, and reciprocating speed) of the existing clinical CPM machine through a wired adapter cable or Bluetooth gateway, and uploads them to the cloud data management unit.

[0032] Dynamic angle verification: The wearable monitoring unit transmits the collected raw IMU data to the cloud in real time, and the cloud calculates the actual flexion and extension angle of the knee joint. The system compares the actual angle with the preset angle of the CPM machine in milliseconds. When the deviation is ≤5°, the training angle is deemed to meet the requirements; when the deviation is >5°, limb displacement or mechanical travel error is determined.

[0033] Closed-loop adjustment: When the angle deviation exceeds the threshold, the CPM machine adapter unit sends a stroke fine-tuning command to the CPM machine control module. The CPM machine automatically adjusts the extension and retraction length of the push rod to correct the actual angle of the knee joint to the preset range, thereby achieving precise matching between mechanical movement and actual posture.

[0034] When not in use with a CPM machine, the wearable monitoring unit independently completes data collection and preliminary calculation, synchronizing real-time angle data to the patient's mobile device via Bluetooth. The mobile device has a built-in lightweight angle calculation algorithm that enables real-time angle display and basic alerts without relying on the cloud, ensuring responsiveness during training. It also caches complete training data and uploads it to the cloud after the network is restored, achieving data completion.

[0035] Cloud-based data processing and evaluation: High-precision angle calculation. The cloud-based data management unit uses an adaptive Kalman filter fusion algorithm to process the raw IMU data: Gravity component decomposition is performed on the accelerometer data to obtain the static tilt angle of the limb. By combining gyroscope data to compensate for angle changes during dynamic motion, the measurement error of the accelerometer under motion is corrected; the coordinate system orientation is calibrated by magnetometer data to offset the angle drift caused by indoor magnetic field interference (such as metal hospital beds and medical devices); based on the calibrated thigh and lower leg coordinate systems, the angle between the two is calculated, and finally the knee flexion and extension angle is obtained, with the calculation accuracy stable within ±1.5°.

[0036] Intelligent Rehabilitation Assessment: The system incorporates a cloud-based clinical rehabilitation database for knee replacement surgery, matching rehabilitation goals to patients at corresponding stages based on postoperative time (1 week, 2 weeks, 1 month, 3 months post-surgery). Angle compliance rate statistics: The system automatically calculates the proportion of the total training time in a single training session where the knee joint angle falls within the preset rehabilitation range, reflecting the standardization of training movements; Rehabilitation trend analysis: Based on data such as daily maximum flexion angle and average flexion-extension speed, an angle change trend curve is generated to visually display the rehabilitation progress; Risk warning: When knee hyperextension >5° or flexion >135° is detected, the risk event is automatically marked and intervention suggestions are generated, such as reducing the range of knee extension and reducing the speed of flexion; Personalized program adjustments: Based on the patient's assessment results and rehabilitation guidelines, the system automatically pushes training suggestions for the next stage, such as increasing the training angle to 0°-50° and increasing the duration of a single training session to 20 minutes.

[0037] The healthcare workstation displays real-time patient training angle curves, target achievement rates, and risk warning information. Healthcare professionals can directly adjust preset parameters of the CPM machine or modify the cloud-based rehabilitation goal database via the workstation, and push personalized rehabilitation plans to patients' mobile devices. Simultaneously, the system supports batch export of patient rehabilitation data for clinical case analysis and research statistics.

[0038] The patient's mobile device displays real-time angle values, a training progress bar, and goal completion status through a visual interface. When the angle does not reach the training target, a voice prompt will indicate that the current angle is 45° and you should continue to bend to 55°. When there is a risk of hyperextension or excessive flexion, a dual warning of vibration and voice will be triggered immediately: Be aware of knee hyperextension and please adjust your posture. After training, a simple rehabilitation report is automatically generated, showing the day's training results and the training plan for tomorrow.

[0039] Family members can synchronize patient rehabilitation data and view daily training progress. When a patient fails to complete training as planned, the system sends a reminder message to the family member to help monitor the patient's rehabilitation adherence.

[0040] Example 2: Ten traditional fixed CPM machines were installed in the orthopedic ward of a tertiary hospital. After applying the system of this invention: Medical staff put a wearable monitoring unit on the patient after knee replacement surgery and connect the CPM machine adapter unit to the CPM machine control port through an adapter cable; Set the CPM machine training angle to 0°-45° and the exercise cycle to 12 seconds / repetition; During training, the cloud data management unit calculates the actual knee joint angle as 0°-43°, which deviates from the preset angle by 2°. Within the normal error range, the system maintains stable monitoring. When the patient's limb shifts and the deviation reaches 6°, the CPM machine adapter unit automatically sends a fine-tuning command, and the CPM machine push rod travel is adjusted by 0.5cm, correcting the actual angle to 45°. After each day's training, the medical workstation automatically generates a rehabilitation report, showing that the training angle achieved the target rate of 96% that day. Based on this, the medical staff adjust the training angle to 5°-10° for the next day.

[0041] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A wearable knee joint rehabilitation training angle monitoring system after knee replacement surgery, characterized in that, It includes a wearable monitoring unit, a CPM machine adaptation unit, a cloud data management unit, and a multi-terminal display unit: the wearable monitoring unit includes a first strap adapted to the thigh segment, a second strap adapted to the calf segment, and a nine-axis inertial measurement unit respectively set on the two straps; The CPM machine adapter unit is used to connect the wearable monitoring unit with the existing clinical CPM machine to enable fine-tuning of data and parameters; the cloud data management unit is used to receive, store and process monitoring data and generate rehabilitation assessment reports; the multi-terminal display unit is used to display real-time angle data and rehabilitation assessment results to medical staff and patients.

2. The wearable knee joint rehabilitation training angle monitoring system according to claim 1, characterized in that, The first and second straps of the wearable monitoring unit are made of high-elastic nylon fabric, with built-in anti-slip silicone strips. The tightness can be adjusted by Velcro, and it is suitable for leg circumferences of 40cm to 70cm. The overall weight does not exceed 50g.

3. The wearable knee joint rehabilitation training angle monitoring system according to claim 1, characterized in that, The nine-axis inertial measurement unit integrates a three-axis accelerometer, a three-axis gyroscope, and a three-axis magnetometer. The installation position corresponds to the lateral condyle region of the knee joint. It uses an adaptive Kalman filter algorithm to fuse the original sensor data, and the knee joint angle calculation accuracy is within ±1.5°.

4. The wearable knee joint rehabilitation training angle monitoring system according to claim 1, characterized in that, The CPM machine adapter unit includes a wired adapter module and a wireless module: The wired adapter module is equipped with multi-specification adapter cables, which are compatible with mainstream CPM machine control ports such as RS232 and TTL. It can read the preset training parameters of the CPM machine and send angle fine-tuning commands. The wireless module has a built-in Bluetooth gateway, which can synchronize monitoring data to the CPM machine's display terminal, allowing medical staff to manually adjust the CPM machine parameters.

5. The wearable knee joint rehabilitation training angle monitoring system according to claim 4, characterized in that, When the measured knee joint angle by the wearable monitoring unit deviates from the preset angle of the CPM machine by ≥5°, the CPM machine adapter unit automatically sends a stroke adjustment command to the CPM machine to correct the displacement of the mechanical push rod of the CPM machine, so that the actual angle returns to the preset range.

6. The wearable knee joint rehabilitation training angle monitoring system according to claim 1, characterized in that, The cloud-based data management unit has a built-in clinical knee replacement surgery rehabilitation target database. Based on the patient's training angle data, it can automatically compare with the rehabilitation standards at the same stage and generate a rehabilitation assessment report that includes the angle achievement rate, the trend of the maximum flexion angle, and risk warnings.

7. The wearable knee joint rehabilitation training angle monitoring system according to claim 1, characterized in that, The medical workstation supports real-time viewing of patients' training angle curves, retrieval of historical rehabilitation reports, and push of personalized rehabilitation plans to patients' mobile devices via the cloud.

8. The wearable knee joint rehabilitation training angle monitoring system according to claim 1, characterized in that, The wearable monitoring unit has a built-in low-power Bluetooth module, can work continuously for ≥8 hours, supports Type-C fast charging, and a 30-minute charge can meet the training and monitoring needs for 4 hours.

9. The wearable knee joint rehabilitation training angle monitoring system according to claim 1, characterized in that, The cloud-based data management unit uses the MQTT protocol to transmit data, encrypts and stores patient data, and associates it with the patient's unique identity ID, which complies with medical data privacy protection standards.

10. A wearable knee joint rehabilitation training angle monitoring system according to claim 1, characterized in that, It has two modes: CPM machine collaborative training and autonomous training. The system works in conjunction with the CPM machine to achieve automatic angle calibration and parameter fine-tuning; the wearable monitoring unit works independently, and training data is automatically uploaded to the cloud, supporting remote viewing and plan adjustment by medical staff.

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