A rotating arthroplasty post-operative prosthetic system with knee joint protection

Abstract

The application discloses a kind of rotation forming postoperative prosthesis system with knee joint protection, including: prosthesis support, fixed cavity, first inertial measurement unit, second inertial measurement unit, controller and motor correction protection device;Prosthesis support is used to replace physiological shank and foot before amputation;Fixed cavity is used to wrap thigh and protect hip joint;First inertial measurement unit is fixed to the lateral wall of fixed cavity, for measuring angular velocity value on the thigh of prosthesis;Second inertial measurement unit is fixed to the shank support part of prosthesis support, for measuring angular velocity value on the shank of prosthesis;Controller is used to calculate the flexion angle of knee joint according to the angular velocity value transmitted by first inertial measurement unit and second inertial measurement unit, and calculate the rotation angle of prosthesis according to the flexion angle of knee joint;Motor correction protection device is fixed on prosthesis support and fixed cavity, for controlling the rotation angle of prosthesis to correct and protect the over-torsion of knee joint according to the control of controller.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, and more particularly to a rotation forming postoperative prosthesis system with knee joint protection. BACKGROUND

[0002] Patients with femur / tibia malignant tumors or severe trauma who must be amputated usually have no lesions in the ankle joint, and the rotation forming is performed to maximize the function of the knee joint of the patient. The surgical feature is to retain the ankle joint during amputation, and to rotate it 180 degrees backward after lifting it to the original knee joint position, so that the ankle joint replaces the function of the pre-amputation knee joint.

[0003] However, the physiological ankle rotation has multi-axis characteristics, while the knee joint is a single-axis rotation like a single-axis hinge. In order to prevent the physiological ankle from replacing the knee joint from turning in and out, a single-axis hinge and a strut are usually installed on both sides of the prosthesis to limit the medial and lateral rotation of the prosthesis knee joint. However, this structure cannot limit the axial rotation angle of the physiological ankle, and the prosthesis wearer is prone to fall or even cause joint sprain when walking or running at a fast pace.

[0004] Therefore, how to provide a rotation forming postoperative prosthesis system with knee joint protection is a problem that those skilled in the art need to solve. SUMMARY

[0005] Therefore, the present application provides a rotation forming postoperative prosthesis system with knee joint protection, which arranges an inertial measurement unit on the thigh and the lower leg of the prosthesis respectively to detect the angle values on the thigh and the lower leg in real time and feed back to the controller, the controller calculates the flexion angle of the knee joint according to the angle values and issues control instructions to the motor, and the motor controls the rotation angle of the prosthesis connecting rod to correct and protect the over-torsion of the knee joint.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A rotation forming postoperative prosthesis system with knee joint protection, comprising: a prosthesis support, a fixed cavity, a first inertial measurement unit, a second inertial measurement unit, a controller and a motor correction protection device.

[0008] The prosthesis support is used to replace the physiological lower leg and foot before amputation;

[0009] The fixed cavity is used to wrap the thigh to protect the hip joint;

[0010] The first inertial measurement unit is fixed to the outer wall of the fixed cavity and is used to measure the angular velocity value on the thigh of the prosthesis;

[0011] The second inertial measurement unit is fixed to the prosthetic support lower leg support part for measuring angular velocity value on the prosthetic lower leg;

[0012] The controller is fixed to the outside wall of the fixed cavity for calculating the knee flexion angle according to the angular velocity value transmitted by the first and second inertial measurement units, and calculating the prosthetic rotation angle according to the knee flexion angle;

[0013] The motor correction protection device is fixed to the prosthetic support and the fixed cavity for regulating the prosthetic rotation angle according to the control of the controller to correct and protect the knee joint from over-torsion.

[0014] Preferably, the motor correction protection device comprises a first connecting rod, a second connecting rod, a rotating shaft and a motor transmission mechanism.

[0015] The upper end of the first connecting rod is provided with a circular ring groove, and a cylindrical head is arranged in the fixed cavity, the cylindrical head matches the circular ring groove, the cylindrical head slides in the circular ring groove during walking, and the lower end of the first connecting rod is connected with the rotating shaft.

[0016] The second connecting rod is fixed in the prosthetic support and connected with the rotating shaft.

[0017] The motor transmission mechanism is connected with the rotating shaft.

[0018] Preferably, the motor transmission mechanism comprises a motor, a first bearing seat, a second bearing seat, a first coupling and a second coupling, the motor is fixed to the outside wall of the fixed cavity, the first bearing seat is fixed to the inside wall of the fixed cavity, the second bearing seat is fixed to the inner wall of the prosthetic support, the motor is connected with the rotating shaft through the second coupling and the first bearing seat, and the rotating shaft is connected with the second connecting rod through the first coupling and the second bearing seat.

[0019] Preferably, it further comprises a plantar pressure sensor module fixed to the plantar heel of the prosthetic support for detecting plantar pressure value, and when the detected plantar pressure value is greater than 0, the knee flexion angle value is calculated.

[0020] Preferably, the first inertial measurement unit, the second inertial measurement unit, the plantar pressure sensor module and the controller are all provided with a Bluetooth module, and the first inertial measurement unit, the second inertial measurement unit and the plantar pressure sensor module realize communication with the controller through the Bluetooth module.

[0021] Preferably, the motor is a two-phase stepping motor.

[0022] Preferably, the specific calculation process of the controller is:

[0023] (1) Establish a mathematical model of prosthesis movement:

[0024] The limb after the person wears the prosthesis is assumed to be a hinge structure, and a prosthesis movement constraint model is established;

[0025] (2) Inertial sensor coordinate system correction:

[0026] ||g1(t)×j1||2-||g2(t)×j2||2=0

[0027] Wherein, j1, j2 are variables, g1, g2 are the angular velocity values measured by the first and second inertial measurement units before correction, ||||2 is the second Euclidean distance, and × represents cross multiplication;

[0028] (3) Calculate the knee joint flexion angle θ(t):

[0029] W i (t)=g i ×j i , i=1,2

[0030]

[0031] Wherein, when i=1, g i represents the angular velocity value measured by the first inertial measurement unit after coordinate system correction, and when i=2, g i represents the angular velocity value measured by the second inertial measurement unit after coordinate system correction.

[0032] According to the above technical solution, compared with the prior art, the present application provides a kind of knee joint protection's rotation shaping post-prosthetic system, inertial measurement unit is arranged on the thigh and lower leg of prosthesis respectively, and the angle value on the thigh and lower leg is detected in real time and fed back to controller, controller calculates the knee joint flexion angle according to the angle value and issues control instruction to motor, and the rotation angle of prosthesis connecting rod is regulated by motor to correct and protect the knee joint over-torsion. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and those skilled in the art can obtain other drawings according to the provided drawings without creative labor.

[0034] Figure 1 The drawing is a structure diagram of a knee joint protection's rotation shaping post-prosthetic system provided by the present application.

[0035] Figure 2 The figure is a side view of the motor correction protection device provided by the application.

[0036] Figure 3 The figure is a front view of the motor correction protection device provided by the application.

[0037] Wherein, 1, prosthesis support, 2, fixed cavity, 3, first inertial measurement unit, 4, second inertial measurement unit, 5, controller, 6, motor correction protection device, 601, first connecting rod, 602, second connecting rod, 603, rotating shaft, 604, motor, 605, first bearing seat, 606 second bearing seat, 607, first coupling, 608, second coupling, 609, circular ring groove, 7, cylindrical head, 8, physiological ankle, 9, physiological foot, 10, plantar pressure sensor module. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0039] The embodiment of the application discloses a kind of with knee joint protection rotary forming post-prosthetic system, as shown in Figure 1 Including: prosthesis support 1, fixed cavity 2, first inertial measurement unit 3, second inertial measurement unit 4, controller 5 and motor correction protection device 6, wherein physiological ankle 8 and physiological foot 9 are as shown in Figure 1 Position, physiological ankle 8 and physiological foot 9 are worn into the inner wall side of prosthesis support 1 when wearing prosthesis;

[0040] Prosthesis support 1 is used to replace physiological calf and foot before amputation;

[0041] Fixed cavity 2 is used to wrap thigh to protect hip joint;

[0042] First inertial measurement unit 3 is fixed to the outer side wall of fixed cavity 2, and is used to measure the angular velocity value on the thigh of prosthesis;

[0043] Second inertial measurement unit 4 is fixed to the calf support part of prosthesis support 1, and is used to measure the angular velocity value on the calf of prosthesis;

[0044] Controller 5 is fixed to the outer side wall of rotary forming prosthesis fixed cavity, and is rigidly connected through screw, and is used to calculate the knee joint flexion angle according to the angular velocity value transmitted by first inertial measurement unit 3 and second inertial measurement unit 4, and calculate the rotation angle of prosthesis according to the knee joint flexion angle;

[0045] The motor correction protection device 6 is fixed in the prosthetic support 1 and the fixed cavity 2, and is used for regulating the rotation angle of the artificial limb to correct and protect the knee joint from over-torsion according to the control of the controller 5.

[0046] Specifically, as shown in Figure 2 and 3 , the motor correction protection device 6 comprises a first connecting rod 601, a second connecting rod 602, a rotating shaft 603 (black filled part in the figure) and a motor transmission mechanism;

[0047] The upper end of the first connecting rod 601 is provided with a circular groove 609, and a cylindrical head 7 is arranged in the fixed cavity, which is matched with the circular groove 609. During walking, the cylindrical head 7 slides in the circular groove 609 to drive the second connecting rod 602 to rotate. The lower end of the first connecting rod 601 is provided with a through hole, which is connected with the rotating shaft 603 in an interference fit. The diameter of the through hole and the rotating shaft 603 is 5mm. The second connecting rod 602 is rigidly fixed in the prosthetic support 1 by screws and is connected with the rotating shaft 603.

[0048] The motor transmission mechanism comprises a motor 604, a first bearing seat 605, a second bearing seat 606, a first coupling 607 and a second coupling 608. The motor 604 is fixed on the outer wall of the fixed cavity 2, close to the physiological ankle position. The first bearing seat 605 is rigidly connected and fixed on the inner wall of the fixed cavity 2, close to the inner wall of the physiological ankle position. The second bearing seat 606 is rigidly connected and fixed on the inner wall of the prosthetic support 1. The motor 604 is connected with the rotating shaft 603 through the second coupling 608 and the first bearing seat 605. The rotating shaft 603 is connected with the second connecting rod 602 through the first coupling 607 and the second bearing seat 606. The motor torsion power is transmitted through the first coupling 607 and the second coupling 608, so that the transmission shaft has a space for radial size adjustment during assembly. The first bearing seat 605 and the second bearing seat 606 have the same effect, which limits the axial and radial movement of the transmission shaft and ensures the rotation accuracy.

[0049] The motor 604 adopts a two-phase stepping motor, and the model can be 57BYGH56-401A (Yuhui). The control mode is pulse control. The motor shaft adopts a 304 stainless steel rotating shaft, which has high strength, is not easy to wear and rust. The motor has a high-performance silicon steel sheet and stator lamination design inside, so that the motor has larger torque, higher precision and lower loss. The motor is used in combination with the controller to realize the regulation and control of the rotation angle of the motor, and then control the rotation angle of the second connecting rod.

[0050] The controller 5 selects the Kaidi Century TB6600 driver, which has the characteristics of sub-division selection (1 / 2 / 4 / 8 / 16 / 32 sub-division), optical coupling isolation signal input, strong anti-interference ability, overheat, overcurrent, undervoltage lock, input voltage anti-reverse connection protection and other functions. The normal movement range of the prosthetic knee joint is 0-100°, and if the controller ADC sampling detects that the knee joint angle deviates from 100°, the controller 5 controls the motor to rotate the corresponding deviation value for correction.

[0051] Specifically, the connection between the first and second inertial measurement units 3 and 4 and the prosthetic limb can be achieved through medical double-sided tape, medical elastic bandage, or rigid connection using screws through threaded holes in the side wall of the prosthetic limb. The first and second inertial measurement units 3 and 4 are equipped with a Bluetooth module and a battery module, model BWT901CL (Shenzhen Wit Intelligent Technology Co., Ltd.), size 42x22x12mm, meeting the performance characteristics of portability and ease of use. The product integrates an attitude solver, which can accurately output the current attitude in a dynamic environment, with a static attitude measurement accuracy of 0.05° and high stability.

[0052] Specifically, it also includes a plantar pressure sensor module 10, which is composed of a plantar pressure sensor, a voltage conversion module, a Bluetooth module, and a power module. The plantar pressure sensor realizes gait recognition and is attached to the heel of the foot. The pressure waveform of human walking is a periodic downward-opening parabolic shape, and the pressure value at the starting point of each cycle is 0. According to the pressure waveform value, the heel sticking point is determined as the starting point of a gait cycle. When the pressure value is greater than 0, it is considered to enter a gait cycle. The pressure value measured by the plantar pressure sensor serves as the starting point for calculating the knee joint angle, i.e., when the plantar pressure value is greater than 0, the knee joint flexion and extension angle value is calculated.

[0053] The plantar pressure sensor selects the FSR resistive film pressure sensor produced by WAAAX Company, with a range of 2.5kg-35kg and a circular shape with a diameter of 4mm. A layer of elastic and relatively stable flexible gasket is added between the sensor and the measured object during use to ensure effective contact between the sensor and the measured object. The pressure sensor output is converted by the voltage conversion module, changing the resistance change to a voltage change in the range of 0-3.3V, which is easy for the ADC of the main control such as the single-chip microcomputer in the controller to read and process. Therefore, the frequency of the voltage conversion module collecting pressure data is set to 30Hz, which can collect gait data under different motion states (standing, fast walking, slow walking, etc.).

[0054] Specifically, the first and second inertial measurement units 3 and 4, the plantar pressure sensor module 10, and the controller 5 are all equipped with Bluetooth modules, and the first and second inertial measurement units 3 and 4 and the plantar pressure sensor module 10 communicate with the controller 5 through the Bluetooth modules.

[0055] The Bluetooth module model is FSC-BT816S, which integrates TI CC2564C Bluetooth 4.2 dual-mode chip and STM32 CPU (Cortex M0), and is a kind of Bluetooth master-slave data transparent and networking module. The controller 5 is a master Bluetooth module, and the first inertial measurement unit 3, the second inertial measurement unit 4 and the plantar pressure sensor module 10 are slave Bluetooth modules. The master Bluetooth module can realize one-to-many intercommunication with the slave Bluetooth modules.

[0056] Specifically, the specific calculation process of the controller is as follows:

[0057] (1) Establish a mathematical model of prosthesis movement:

[0058] The limb after the person wears the prosthesis is assumed to be a hinge structure, and a prosthesis movement constraint model is established;

[0059] (2) Inertial sensor coordinate system correction:

[0060] Since the installation direction of the inertial unit is inconsistent with the corresponding limb coordinate system, j1 and j2 variables are introduced for correction and compensation. The angular velocity values obtained by the inertial measurement unit before correction are g1 and g2, which are corrected by the following formula:

[0061] ||g1(t) x j1||2-||g2(t) x j2||2=0

[0062] Wherein, j1 and j2 are variables, g1 and g2 are the angular velocity values measured by the first and second inertial measurement units before correction, ||||2 is the second Euclidean distance, and x represents cross multiplication.

[0063] (3) Calculate the knee joint flexion angle θ(t):

[0064] The calculation of j1 and j2 variables can be solved by gradient descent method, Gauss-Newton method or Levenberg-Marquardt method, least squares method and other parameter estimation methods. The corrected angular velocity W1 and W2 can be calculated by integrating the angular velocity to calculate the knee joint angle θ(t) based on the two inertial sensors.

[0065] W i (t)=g i x j i ,i=1,2

[0066]

[0067] Wherein, when i=1, g i represents the angular velocity value measured by the first inertial measurement unit after coordinate system correction, and when i=2, g i represents the angular velocity value measured by the second inertial measurement unit after coordinate system correction.

[0068] The various embodiments described in this specification are presented by way of example, and each embodiment is not necessarily composed of all features described with respect to other embodiments. Each embodiment described in this specification can be implemented in conjunction with one or more other embodiments described in this specification without departing from the scope or spirit of the application. In the drawings, the same reference numbers and designations in different drawings indicate embodiments that are the same, functionally similar, comiieet with one or more of the same requirements, or are otherwise functionally related. The various embodiments described in this specification can be implemented in conjunction with computer hardware, computer program products, and / or computer-implemented methods.

[0069] The previous description of the disclosed embodiments is not intended to limit the application, as claimed, but to provide an illustrative description. Various modifications and changes can be made to the described embodiments without departing from the spirit and scope of the application. The scope of the application is defined by the appended claims, along with the full scope of equivalents to which such claims are entitled. It is intended that the application encompass all such modifications and changes as fall within the scope of the appended claims.

Claims

1. A post-operative rotationplasty prosthetic system with knee joint protection, characterized in that: include: Prosthetic support, fixed cavity, first inertial measurement unit, second inertial measurement unit, controller and motor correction protection device; The prosthetic support is used to replace the physiological lower leg and foot before amputation; The fixed cavity is used to wrap the thigh and protect the hip joint; The first inertial measurement unit is fixed to the outer side wall of the fixed cavity and is used to measure the angular velocity value of the prosthetic thigh; The second inertial measurement unit is fixed to the prosthetic shank support portion and is used to measure the angular velocity value of the prosthetic shank; The controller is fixed to the outer wall of the fixed cavity, and is used to calculate the knee joint flexion and extension angle according to the angular velocity values ​​transmitted by the first inertial measurement unit and the second inertial measurement unit, and calculate the prosthesis rotation angle according to the knee joint flexion and extension angle; The motor correction and protection device is fixed to the prosthesis support and fixing cavity, and is used to adjust the rotation angle of the prosthesis according to the control of the controller to correct and protect the knee joint from excessive torsion; The motor correction protection device includes a first connecting rod, a second connecting rod, a rotating shaft and a motor transmission mechanism; The upper end of the first connecting rod is provided with a circular groove, and the fixed cavity is provided with a cylindrical head, which matches the circular groove. The cylindrical head slides in the circular groove during walking, and the lower end of the first connecting rod is connected to the rotating shaft; The second connecting rod is fixed in the prosthetic support and connected to the rotating shaft; The motor transmission mechanism is connected to the rotating shaft; The motor transmission mechanism includes a motor, a first bearing seat, a second bearing seat, a first coupling and a second coupling. The motor is fixed to the outer wall of the fixed cavity, the first bearing seat is fixed to the inner wall of the fixed cavity, and the second bearing seat is fixed to the inner wall of the prosthesis support. The motor is connected to the rotating shaft through the second coupling and the first bearing seat, and the rotating shaft is connected to the second connecting rod through the first coupling and the second bearing seat.

2. A post-operative rotationplasty prosthetic system with knee joint protection according to claim 1, characterized in that: It also includes a plantar pressure sensor module, which is fixed at the heel of the prosthetic support and is used to detect the plantar pressure value. When the plantar pressure value is detected to be greater than 0, the knee joint flexion and extension angle value is calculated.

3. A post-operative rotationplasty prosthetic system with knee joint protection according to claim 2, characterized in that: The first inertial measurement unit, the second inertial measurement unit, the plantar pressure sensor module and the controller are all provided with a Bluetooth module, and the first inertial measurement unit, the second inertial measurement unit and the plantar pressure sensor module communicate with the controller through the Bluetooth module.

4. A post-operative rotationplasty prosthetic system with knee joint protection according to claim 1, characterized in that: The motor is a two-phase stepping motor.

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