CN219021769U

CN219021769U - Knee joint pressure measuring device

Info

Publication number: CN219021769U
Application number: CN202222593299.9U
Authority: CN
Inventors: 张海宁
Original assignee: Shandong Yi Mai Medical Technology Co ltd; Affiliated Hospital of University of Qingdao
Current assignee: Shandong Yi Mai Medical Technology Co ltd; Affiliated Hospital of University of Qingdao
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2023-05-16
Anticipated expiration: 2032-09-29

Abstract

The application discloses a knee joint pressure measuring device, comprising a lower shell; the circuit board is arranged above the lower shell and comprises a main control chip, a wireless communication module and two groups of symmetrically arranged pressure sensor arrays; the two metal plates are respectively arranged above the two groups of pressure sensor arrays, and the induction part of each pressure sensor of each group of pressure sensor arrays is contacted with the corresponding metal plate; the upper shell is connected with the lower shell and comprises a soft rubber part, two groups of hard plastic movable parts are arranged on the inner side of the soft rubber part, and the two groups of hard plastic movable parts are respectively arranged above the two metal plates; each group of hard plastic movable parts are simultaneously contacted with the soft rubber part and the corresponding metal plate. The upper shell is composed of soft rubber and hard plastic, and the loss of pressure on the shell can be reduced due to the fact that the soft rubber is deformed when the upper shell is subjected to pressure, so that measurement accuracy can be improved, dependence of the measurement accuracy on the manufacturing accuracy of the shell is reduced, and production efficiency and straight-through rate are improved.

Description

Knee joint pressure measuring device

Technical Field

The application relates to the technical field of medical equipment, in particular to a knee joint pressure measuring device.

Background

Proper ligament release and soft tissue balance are key to total knee replacement surgery. The existing device for assisting soft tissue balance adopts a mode of embedding a strain force sensor in a shell, wherein the shell is split into an upper shell 1 and a lower shell 2, and the shell is made of plastic materials. As shown in fig. 1, in the conventional device for assisting in balancing soft tissue, a sensor 3 is disposed between an upper shell and a lower shell, the lower shell is disposed on a section of a tibia 4, and has a supporting function, the lower shell 2 and the upper shell 1 are connected through processes such as gluing or ultrasonic welding, a femoral condyle 5 is pressed on the upper shell 1 of the device, and the pressure is transmitted to the sensor 3 through the upper shell 1, so that a pressure value is output

However, such prior art devices that assist in balancing soft tissue have mainly the following drawbacks:

(1) The shell is made of plastic, residual stress and deformation can be generated in the injection molding process, the requirement on the precision of the shell is high on the premise of guaranteeing the measurement precision, and the production straight-through rate of the product is low;

(2) The deformation of the upper shell plastic material can share a large proportion of force when being pressed, and the force shared by each shell is different, so that the product precision is reduced and the production complexity is increased;

(3) The measurement of the pressure point position is inaccurate;

(4) The upper shell is integrated, and left and right side deformation is mutually influenced under the action of pressure.

Disclosure of Invention

For this reason, this application provides a knee joint pressure measurement device to solve the current balanced device epitheca of supplementary soft tissue that prior art exists and be the integral type, the side warp is influenced each other about under the pressure effect, and the shell adopts plastic material, to the higher problem of precision requirement.

In order to achieve the above object, the present application provides the following technical solutions:

a knee joint pressure measurement device, comprising:

a lower case;

the circuit board is arranged above the lower shell and comprises a main control chip, a wireless communication module and two groups of symmetrically arranged pressure sensor arrays; each group of pressure sensor array comprises a plurality of pressure sensors, the data output end of each pressure sensor is electrically connected with the corresponding data input end of the main control chip, the data output end of the main control chip is electrically connected with the data input end of the wireless communication module, and the wireless communication module is used for establishing wireless communication connection with an external receiving device;

the two metal plates are respectively arranged above the two groups of pressure sensor arrays, and the induction part of each pressure sensor of each group of pressure sensor arrays is contacted with the corresponding metal plate;

the upper shell is connected with the lower shell and comprises a soft rubber part, the surface shape of the soft rubber part is matched with the tibia osteotomy surface, two groups of hard plastic movable parts are arranged on the inner side of the soft rubber part, and the two groups of hard plastic movable parts are respectively arranged above the two metal plates; each group of hard plastic movable parts are simultaneously contacted with the soft rubber parts and the corresponding metal plates, so that when the soft rubber parts are subjected to pressure, the pressure is transmitted to the induction parts of the corresponding pressure sensors through the hard plastic movable parts and the metal plates.

Optionally, a concave fixing slot is formed in the bottom of the lower shell, so that the measuring device is prevented from sliding on the tibial plateau when the measuring device is used.

Optionally, each pressure sensor and the main control chip are welded on the circuit board.

Optionally, the metal plate is made of stainless steel, and the thickness of the metal plate is 2mm.

Optionally, a plurality of reinforcing ribs are further arranged on the lower shell, the reinforcing ribs correspond to the pressure sensors one by one, and the bottom of each pressure sensor is contacted with the top of the corresponding reinforcing rib.

Optionally, each set of pressure sensor arrays includes three pressure sensors, specifically a first pressure sensor, a second pressure sensor, and a third pressure sensor; the first pressure sensor is arranged at the upper position of the circuit board, the second pressure sensor is arranged at the side edge position of the circuit board, and the third pressure sensor is arranged at the lower position of the circuit board.

Further alternatively, the linear distance between the first pressure sensor and the second pressure sensor is 17.5mm, the linear distance between the first pressure sensor and the third pressure sensor is 20.5mm, and the linear distance between the second pressure sensor and the third pressure sensor is 12.3mm;

the included angle formed by the connecting line of the first pressure sensor and the second pressure sensor and the connecting line of the first pressure sensor and the third pressure sensor is 36 degrees, the included angle formed by the connecting line of the second pressure sensor and the first pressure sensor and the connecting line of the second pressure sensor and the third pressure sensor is 86 degrees, and the included angle formed by the connecting line of the third pressure sensor and the first pressure sensor and the connecting line of the third pressure sensor and the second pressure sensor is 58 degrees.

Optionally, two groups of metal plate positioning column arrays are symmetrically arranged on the lower shell, and each group of metal plate positioning column array comprises a plurality of metal plate positioning columns; the circuit board is provided with a plurality of holes, the periphery of each metal plate is provided with a plurality of grooves, and the holes and the grooves are in one-to-one correspondence with the metal plate positioning columns; each metal plate positioning column of each group of metal plate positioning column array penetrates through the corresponding hole and is clamped in the corresponding groove on the periphery of the corresponding metal plate.

Optionally, the upper shell further comprises a hard plastic fixing part, and the soft rubber part is connected with the lower shell through the hard plastic fixing part.

Optionally, the measuring device further comprises a battery, and a voltage output end of the battery is electrically connected with a voltage input end of the main control chip.

Compared with the prior art, the application has the following beneficial effects:

1. the utility model provides a knee joint pressure measuring device's new hardware architecture, the knee joint pressure measuring device that this application embodiment provided comprises epitheca, inferior valve, circuit board and metal sheet, and the epitheca can be through the pressure sensor on the circuit board of the pressure transmission that the metal sheet will receive; the upper shell consists of soft rubber and hard plastic, the soft rubber is an ultra-elastic body, and the deformation of the soft rubber part can reduce the loss of pressure on the shell when the soft rubber part is subjected to pressure, so that the measurement precision can be improved, the dependence of the measurement precision on the manufacturing precision of the shell is reduced, and the production efficiency and the straight-through rate are improved; meanwhile, the hard plastic movable part of the upper shell is divided into the left side and the right side, so that the mutual influence of the left side and the right side under the action of pressure is avoided.

2. The metal plate has high rigidity, is arranged on the pressure sensor array, and can regularly distribute pressure on the sensor array, so that the application can lay a foundation for improving the position measurement accuracy of the pressure point.

3. Two sets of pressure sensor array symmetry pendulum cloth in this application, every pressure sensor array of group all includes a plurality of pressure sensor, can measure knee joint pressure in full knee joint replacement art, and the quantity of the pressure sensor that sets up simultaneously compares current supplementary soft tissue balanced device more to can cover bigger effective measurement area, make the pressure of internal and external condyle when can measuring full knee joint replacement simultaneously, and then can promote the accuracy to knee joint pressure measurement.

4. The lower shell is also provided with a fixing clamping groove, so that the measurement distortion of pressure and pressure point positions caused by the sliding of the measuring device on the tibia platform in the use process can be prevented.

Drawings

For a more visual illustration of the prior art and the present application, several exemplary drawings are presented below. It should be understood that the specific shape and configuration shown in the drawings should not be considered in general as limiting upon the practice of the present application; for example, based on the technical concepts and exemplary drawings disclosed herein, those skilled in the art have the ability to easily make conventional adjustments or further optimizations for the add/subtract/assign division, specific shapes, positional relationships, connection modes, dimensional scaling relationships, etc. of certain units (components).

Fig. 1 is a schematic diagram of an application of a conventional device for assisting in balancing soft tissues.

Reference numerals illustrate:

1. an upper case; 2. a lower case; 3. a sensor; 4. tibia; 5. femoral condyles.

Fig. 2 is a schematic overall structure of a knee joint pressure measurement device according to an embodiment of the present disclosure;

FIG. 3 is an exploded view of a knee joint pressure measurement device according to an embodiment of the present disclosure;

fig. 4 is a circuit block diagram of a knee joint pressure measurement device according to an embodiment of the present application;

FIG. 5 is a schematic diagram of two sets of pressure sensor arrays according to an embodiment of the present application;

FIG. 6 is a schematic diagram of another view of two sets of pressure sensor arrays according to an embodiment of the present application;

fig. 7 is a schematic cross-sectional view of a knee joint pressure measurement device according to an embodiment of the present application.

Reference numerals illustrate:

1. a lower case; 11. a concave fixing clamping groove; 12. reinforcing ribs; 13. a metal plate positioning column; 14. a clamping column;

2. a circuit board; 21. a main control chip; 22. a wireless communication module; 23. a pressure sensor; 24. a hole; 25. a second groove;

3. a metal plate; 31. a first groove;

4. an upper case; 41. a soft rubber part; 42. a hard plastic movable part; 43. a hard plastic fixing portion;

5. and a battery.

Detailed Description

The present application is further described in detail below with reference to the attached drawings.

In the description of the present application: unless otherwise indicated, the meaning of "a plurality" is two or more. The terms "first," "second," "third," and the like in this application are intended to distinguish between the referenced objects without a special meaning in terms of technical connotation (e.g., should not be construed as emphasis on degree or order of importance, etc.). The expressions "comprising", "including", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

The terms such as "upper", "lower", "left", "right", "middle", and the like, as referred to in this application, are generally used for convenience in visual understanding with reference to the drawings, and are not intended to be an absolute limitation of the positional relationship in actual products. Such changes in relative positional relationship are considered to be within the scope of the present description without departing from the technical concepts disclosed herein.

In an embodiment of the present application, there is provided a knee joint pressure measurement apparatus, referring to an overall structural schematic diagram of fig. 2, an explosion schematic diagram of fig. 3, and a circuit structural schematic diagram of fig. 4, the apparatus including:

a lower case 1 having a planar overall shape;

the circuit board 2 is arranged above the lower shell 1 and assembled on the lower shell 1, and is conformal with the inner cavity of the device; the circuit board 2 comprises a main control chip 21, a wireless communication module 22 and two groups of pressure sensor arrays symmetrically arranged on the left side and the right side; each group of pressure sensor array comprises a plurality of pressure sensors 23, the data output end of each pressure sensor 23 is electrically connected with the corresponding data input end of the main control chip 21, the data output end of the main control chip 21 is electrically connected with the data input end of the wireless communication module 22, and the wireless communication module 22 is used for establishing wireless communication connection with an external receiving device; the external receiving device may be various terminal devices including, but not limited to, various smartphones, notebook computers, and computers; each pressure sensor 23 is used for measuring the pressure generated by the femoral condyle pressure on the device when the tibial osteotomy face is in contact with the measuring device;

the two metal plates 3 are arranged on the left side and the right side, are respectively arranged above the two groups of pressure sensor arrays, and the induction part of each pressure sensor 23 of each group of pressure sensor arrays is contacted with the corresponding metal plate 3;

the upper shell 4 is connected with the lower shell 1 and comprises a soft rubber part 41, the surface shape of the soft rubber part 41 is matched with the tibia-osteotomy surface, two groups of hard plastic movable parts 42 are arranged on the inner side of the soft rubber part 41, and the two groups of hard plastic movable parts 42 are respectively arranged above the two metal plates 3; each set of the hard plastic movable portions 42 is simultaneously in contact with the soft rubber portion 41 and the corresponding metal plate 3, so that when the soft rubber portion 41 is subjected to pressure, the pressure can be transmitted to the sensing portions of the corresponding pressure sensors 23 via the hard plastic movable portions 42 and the metal plate 3.

In other words, the measuring device is composed of a shell and a device inside the shell, the shell is divided into an upper shell 4 and a lower shell 1, and the upper shell 4 and the lower shell 1 are connected into an integrated structure through an adhesive or ultrasonic welding process.

Further, the bottom (lower) plane of the lower shell 1 is further provided with a concave fixing slot 11 for preventing the measuring device from sliding on the tibial plateau during the use of the measuring device, and for limiting the tibial plateau, i.e. for fixing the position of the measuring device when measuring knee joint pressure.

Further, each of the pressure sensors 23 and the main control chip 21 is fixed to the circuit board 2 by a soldering process, wherein each of the pressure sensors 23 penetrates through the circuit board 2. That is, the sensing portion of the top of each pressure sensor 23 is located above the circuit board 2, and the bottom of each pressure sensor 23 is located below the circuit board 2.

Further, the wireless communication module 22 may be, but is not limited to, a bluetooth module or a 433m wireless module. The main control chip 21 of the circuit board 2 is used for receiving the signals of each pressure sensor 23, packaging the data and transmitting the data to an external receiving device in a wireless mode (wireless communication mode such as Bluetooth, 433MHz and the like) by means of the wireless communication module 22.

Further, the material of the metal plate 3 may be, but not limited to, stainless steel, having a sufficiently high rigidity, and the thickness of the metal plate 3 is 2mm. The metal plate 3 serves to conduct pressure and to regularly distribute the pressure on the sensor arrays on the left and right sides, thereby improving the measurement accuracy of the pressure point positions.

Further, the lower shell 1 is further provided with a plurality of reinforcing ribs 12 (square rib positions), the reinforcing ribs 12 are in one-to-one correspondence with the pressure sensors 23, and the bottom of each pressure sensor 23 is in contact with the top of the corresponding reinforcing rib 12. That is, how many pressure sensors 23 are provided with how many reinforcing ribs 12 are provided, and when the reinforcing ribs 12 are provided, each reinforcing rib 12 is provided below the corresponding pressure sensor 23 to provide a supporting effect for the corresponding pressure sensor 23.

Further, the upper case 4 further includes a hard plastic fixing portion 43, and the soft rubber portion 41 is connected to the lower case 1 through the hard plastic fixing portion 43. In other words, the upper case 4 is composed of an upper case soft rubber part 41, an upper case hard plastic fixing part 43 and an upper case hard plastic movable part 42, which are manufactured by a two-shot injection molding process, so as to realize a soft and hard combination effect, the hard plastic fixing part 43 is connected with the lower case 1, when in use, pressure acts on the soft rubber part 41 and the hard plastic movable part 42, and the hard plastic movable part 42 transmits the pressure to the corresponding pressure sensor array through the metal plate 3.

The pressure conduction is realized through the deformation of the soft rubber part 41, and the soft rubber is an ultra-elastic body, so that the loss of the pressure on the shell can be reduced to a great extent by controlling the hardness of the soft rubber, the dependence of the measurement precision on the precision of the shell is reduced, and the measurement precision and the production straight-through rate are improved. Meanwhile, since the upper case hard plastic movable portion 42 is divided into the left and right sides, the left and right sides are prevented from being affected by each other under the pressure, that is, the effect that the left and right side pressures are not affected by each other is achieved. In addition, the accuracy of pressure point position measurement can be improved by conducting pressure through the metal plate 3 (steel plate).

Further, the measuring device further comprises a battery 5, the battery 5 can be arranged above the main control chip 21, and a voltage output end of the battery 5 is electrically connected with a voltage input end of the main control chip 21. The battery 5 may be a button cell battery for providing the required operating voltages for the modules of the measuring device, including each pressure sensor 23 and including the main control chip 21, supplying power to the pressure sensors 23 and the control circuit.

Further, the structure of the two sets of pressure sensor arrays is shown in fig. 5. The two groups of pressure sensor arrays are arranged on the left side and the right side of the lower shell 1, three pressure sensors 23 are respectively arranged on the left side and the right side, and correspondingly, 3 square frame-shaped rib positions are respectively arranged on the left side and the right side of the upper part of the lower shell 1, and play a role in supporting the square frame-shaped rib positions. The two groups of pressure sensor arrays are arranged in a butt-array mode along the central axis of the measuring device, and can simultaneously measure the pressure of the medial condyle and the lateral condyle during total knee replacement.

The arrangement of each of the pressure sensor arrays on the left and right sides is constructed as shown in fig. 5: each group of pressure sensor arrays comprises three pressure sensors 23 which are distributed in a triangular shape, the three pressure sensors 23 are respectively marked as a first pressure sensor A, a second pressure sensor B and a third pressure sensor C, the first pressure sensor A is arranged at the upper position of the circuit board 2, the second pressure sensor B is arranged at the side position of the circuit board 2, and the third pressure sensor C is arranged at the lower position of the circuit board 2.

Meanwhile, the placement of the three pressure sensors 23 satisfies the following position special requirements: the linear distance between the first pressure sensor A and the second pressure sensor B is 17.5mm, the linear distance between the first pressure sensor A and the third pressure sensor C is 20.5mm, and the linear distance between the second pressure sensor B and the third pressure sensor C is 12.3mm.

In addition, as shown in fig. 6, θ1 is an angle formed by a connection line between the first pressure sensor a and the second pressure sensor B and a connection line between the first pressure sensor a and the third pressure sensor C, θ2 is an angle formed by a connection line between the second pressure sensor B and the first pressure sensor a and a connection line between the second pressure sensor B and the third pressure sensor C, and θ3 is an angle formed by a connection line between the third pressure sensor C and the first pressure sensor a and a connection line between the third pressure sensor C and the second pressure sensor B; among the angles formed, the angle θ1 was 36 °, the angle θ2 was 86 °, and the angle θ3 was 58 °.

Further, in order to better fix and limit the circuit board 2 and the metal plate 3, two groups of metal plate positioning column arrays are symmetrically arranged on the left side and the right side of the upper part of the lower shell 1, and each group of metal plate positioning column arrays comprises a plurality of metal plate positioning columns 13; correspondingly, the circuit board 2 is provided with a plurality of holes 24, the periphery of each metal plate 3 is provided with a plurality of first grooves 31, the holes 24 and the first grooves 31 are in one-to-one correspondence with the metal plate positioning columns 13, that is, how many metal plate positioning columns 13 are provided, and how many holes 24 and first grooves 31 are required to be provided correspondingly. Each metal plate positioning post 13 of each set of metal plate positioning post arrays penetrates a corresponding hole 24 on the circuit board 2 and is clamped or embedded in a corresponding first groove 31 on the periphery of the corresponding metal plate 3. Therefore, the two metal plates 3 can be clamped between the corresponding metal plate positioning column arrays and fixed through the corresponding metal plate positioning column arrays, so that the two metal plates 3 cannot be easily shifted when in use, and the accuracy of the measuring device on pressure measurement is ensured.

Since each group of pressure sensor arrays comprises three pressure sensors 23, three metal plate positioning columns 13 are respectively arranged on the left side and the right side of the upper part of the lower shell 1 to limit the circuit board 2 and the metal plate 3.

Further, a plurality of clamping columns 14 (also can be regarded as rib positions) are arranged on the periphery of the lower shell 1, and correspondingly, a plurality of second grooves 25 are also arranged on the circuit board 2, and the clamping columns 14 are in one-to-one correspondence with the second grooves 25; that is, how many clamping columns 14 are provided, and how many second grooves 25 are correspondingly provided, when the circuit board 2 is assembled, each clamping column 14 can be clamped in the corresponding second groove 25, so that a good limiting effect can be achieved on the circuit board 2.

In order to more intuitively show the internal configuration of the present application, a cross-sectional view of the present application is shown in fig. 7.

The application method comprises the following steps: after the artificial knee replacement osteotomy is completed, placing the knee pressure measurement device between the patient's knee femoral prosthesis and tibial prosthesis; then the knee joint of the movable patient performs flexion and extension movements, at this time, the pressure sensor 23 generates a pressure signal after detecting the pressure and sends the pressure signal to the main control chip 21, and the main control chip 21 packages the data and sends the data to an external receiving device in a wireless mode. So that doctors can know the knee joint pressure information of the patients through the external receiving device; and then the knee joint pressure measuring device is taken down, the knee joint pressure information provides powerful basis for the subsequent operation of the patient, and doctors are guided to finish accurate knee joint soft tissue loosening, so that the personalized operation treatment is realized.

The utility model provides a knee joint pressure measuring device's new hardware architecture, the knee joint pressure measuring device that this application embodiment provided comprises epitheca, inferior valve, circuit board and metal sheet, and the epitheca can be through the pressure sensor on the circuit board of the pressure transmission that the metal sheet will receive; the upper shell consists of soft rubber and hard plastic, the soft rubber is an ultra-elastic body, and the deformation of the soft rubber part can reduce the loss of pressure on the shell when the soft rubber part is subjected to pressure, so that the measurement precision can be improved, the dependence of the measurement precision on the manufacturing precision of the shell is reduced, and the production efficiency and the straight-through rate are improved; meanwhile, the hard plastic movable part of the upper shell is divided into the left side and the right side, so that the mutual influence of the left side and the right side under the action of pressure is avoided.

In addition, the metal plate has high rigidity, is arranged on the pressure sensor array, and can regularly distribute pressure on the sensor array, so that the pressure point position measurement device can lay a foundation for improving the measurement accuracy of the pressure point position (the position of the femur applying pressure to the measurement device).

Two sets of pressure sensor array symmetry pendulum cloth in this application, every pressure sensor array of group all includes a plurality of pressure sensor, can measure knee joint pressure in full knee joint replacement art, and the quantity of the pressure sensor that sets up simultaneously compares current supplementary soft tissue balanced device more to can cover bigger effective measurement area, make the pressure of internal and external condyle when can measuring full knee joint replacement simultaneously, and then can promote the accuracy to knee joint pressure measurement.

The lower shell is also provided with a fixing clamping groove, so that the measurement distortion of pressure and pressure point positions caused by the sliding of the measuring device on the tibia platform in the use process can be prevented.

Any combination of the technical features of the above embodiments may be performed (as long as there is no contradiction between the combination of the technical features), and for brevity of description, all of the possible combinations of the technical features of the above embodiments are not described; these examples, which are not explicitly written, should also be considered as being within the scope of the present description.

The foregoing has outlined and detailed description of the present application in terms of the general description and embodiments. It should be appreciated that numerous conventional modifications and further innovations may be made to these specific embodiments, based on the technical concepts of the present application; but such conventional modifications and further innovations may be made without departing from the technical spirit of the present application, and such conventional modifications and further innovations are also intended to fall within the scope of the claims of the present application.

Claims

1. A knee joint pressure measurement device, comprising:

a lower case;

2. The knee joint pressure measurement device of claim 1, wherein the bottom of the inferior shell is provided with a concave fixation slot for preventing the measurement device from sliding on the tibial plateau when the measurement device is in use.

3. The knee joint pressure measurement device of claim 1, wherein each of the pressure sensors and the master control chip are soldered to the circuit board.

4. The knee joint pressure measurement apparatus according to claim 1, wherein the metal plate is made of stainless steel, and the thickness of the metal plate is 2mm.

5. The knee joint pressure measurement apparatus of claim 1, wherein the lower shell is further provided with a plurality of reinforcing ribs, the reinforcing ribs are in one-to-one correspondence with the pressure sensors, and the bottom of each pressure sensor is in contact with the top of the corresponding reinforcing rib.

6. The knee joint pressure measurement device of claim 1, wherein each set of pressure sensor arrays comprises three pressure sensors, in particular a first pressure sensor, a second pressure sensor and a third pressure sensor; the first pressure sensor is arranged at the upper position of the circuit board, the second pressure sensor is arranged at the side edge position of the circuit board, and the third pressure sensor is arranged at the lower position of the circuit board.

7. The knee joint pressure measurement apparatus of claim 6, wherein the first and second pressure sensors have a linear distance of 17.5mm, the first and third pressure sensors have a linear distance of 20.5mm, and the second and third pressure sensors have a linear distance of 12.3mm;

8. The knee joint pressure measurement apparatus of claim 1, wherein the lower shell is further symmetrically provided with two sets of metal plate positioning post arrays, each set of metal plate positioning post arrays comprising a plurality of metal plate positioning posts; the circuit board is provided with a plurality of holes, the periphery of each metal plate is provided with a plurality of grooves, and the holes and the grooves are in one-to-one correspondence with the metal plate positioning columns; each metal plate positioning column of each group of metal plate positioning column array penetrates through the corresponding hole and is clamped in the corresponding groove on the periphery of the corresponding metal plate.

9. The knee joint pressure measurement device of claim 1, wherein the upper shell further comprises a hard plastic fixation portion, the soft gel portion being coupled to the lower shell by the hard plastic fixation portion.

10. The knee joint pressure measurement device of claim 1, further comprising a battery, wherein a voltage output of the battery is electrically connected to a voltage input of the main control chip.