CN113017934A

CN113017934A - Dual-mode mechanical detection pad of PS type TKA prosthesis

Info

Publication number: CN113017934A
Application number: CN202110248515.3A
Authority: CN
Inventors: 薛宁; 尹思远; 刘春秀; 刘铁柱; 关振鹏; 张克石; 尤昌华; 孙旭光
Original assignee: PEKING UNIVERSITY SHOUGANG HOSPITAL; Aerospace Information Research Institute of CAS
Current assignee: PEKING UNIVERSITY SHOUGANG HOSPITAL; Aerospace Information Research Institute of CAS
Priority date: 2021-03-05
Filing date: 2021-03-05
Publication date: 2021-06-25

Abstract

The present disclosure provides a dual-mode mechanical detection spacer for a PS-type TKA prosthesis, comprising: the upper surface comprises a central upright post, and a plurality of strain gauges are implanted in the central upright post; the piezoresistive strain array unit is arranged at the joint of the middle part of the gasket and the lower surface of the top of the gasket and converts the transverse shearing force applied to the strain gauge and the vertical shearing stress applied to the detection gasket into electric signals; and the bottom of the pad is provided with a signal processing circuit for acquiring the electric signal and converting the electric signal into a digital signal.

Description

Dual-mode mechanical detection pad of PS type TKA prosthesis

Technical Field

The disclosure relates to the technical field of medical instruments, in particular to a dual-mode mechanical detection pad of a PS type TKA prosthesis.

Background

The 21 st century is entered, the aging problem of the Chinese population is gradually highlighted, and the proportion of the Chinese population over 65 years old to the total population of China is more than 20% by about 2033 years according to the prediction of relevant data of the State statistical office, which marks that China formally enters a super aging society. For the middle-aged and elderly population, various senile diseases seriously affect the daily life quality of the population due to the decline of body functions and long-term loss. Knee osteoarthritis is one of the most common middle-aged and old-aged diseases, for patients with advanced knee osteoarthritis, the recovery of the existing life quality is difficult, and Total Knee Arthroplasty (TKA) is one of the most ideal means for treating advanced arthritis to a certain extent.

The artificial joint prosthesis is mainly composed of three parts, namely a femoral prosthesis, a prosthetic liner and a tibial prosthesis, wherein the prosthetic liner has the function of being equal to a meniscus, bears the pressure from the femur while maintaining the stability of the whole joint, and is easy to wear in the actual use process. The reasonable placement of the gasket and the dynamic adjustment of the thickness of the gasket can avoid stress concentration to a certain extent, thereby avoiding excessive abrasion of a certain area of the gasket in use. In the actual operation process, the thickness and the placement position of the prosthesis liner have no fixed standards and completely depend on the individual operation experience of the primary surgeon, so that the operation effect of each case is different.

Therefore, it is an urgent technical problem to provide a pressure detection pad for monitoring the stress and distribution of a prosthesis in real time during an operation.

Disclosure of Invention

Technical problem to be solved

Based on the problems, the dual-mode mechanical detection pad of the PS-type TKA prosthesis is provided by the disclosure, so that the technical problems that the effect difference among individuals is large due to the fact that the thickness and the placement position of the pad of the prosthesis are not standardized, the transverse shearing force of a central upright column is difficult to detect and the like in the prior art are solved.

(II) technical scheme

The present disclosure provides a dual-mode mechanical detection spacer for a PS-type TKA prosthesis, comprising: the top of the liner is used for connecting and limiting the corresponding bottom end of the femur, the upper surface comprises a central upright post, and a plurality of strain gauges are implanted in the central upright post; the piezoresistive strain array unit is arranged at the joint of the middle part of the gasket and the lower surface of the top of the gasket and converts the transverse shearing force applied to the strain gauge and the vertical shearing stress applied to the detection gasket into electric signals; and the bottom of the liner is provided with a signal processing circuit which is used for acquiring an electric signal and converting the electric signal into a digital signal.

In an embodiment of the disclosure, a piezoresistive strain array cell includes an upper electrode structure layer, a lower electrode structure layer, and a piezoresistive sensitive layer between the upper electrode structure layer and the lower electrode structure layer.

In embodiments of the present disclosure, the piezoresistive sensitive layer includes a strain array and a piezoresistive array.

In an embodiment of the disclosure, the signal processing circuitry includes array scanning circuitry for connecting and scanning the strain array and the piezoresistive array.

In the disclosed embodiment, the strain array comprises a plurality of first piezoresistive sensing blocks respectively connected to a plurality of strain gauges; when the central upright post is subjected to transverse shear stress, the strain gauge can deform, so that the array scanning circuit obtains a first electric signal reflecting the transverse shear stress on the central upright post.

In the disclosed embodiment, the piezoresistive array comprises a plurality of second piezoresistive sensitive blocks, and the second piezoresistive sensitive blocks deform when receiving a vertical shear stress, so that the array scan circuit obtains a second electrical signal reflecting the vertical shear stress to which the detection pad is subjected.

In the embodiment of the disclosure, the whole middle part of the pad is in a soft plate shape, copper foil is used as an electrode contact point of the piezoresistive strain array unit and a lead wire for connecting an electrode, the tail end of the piezoresistive strain array unit is led out through a gold finger, metal wires for connecting rows and columns of the piezoresistive strain array are distributed on different layers, and an electric signal is led out by using a metal electrode site.

In the embodiment of the present disclosure, the second piezoresistive sensitive block is made of any one of carbon nanotube-PDMS, graphene-PDMS, or a rubber material mixed with metal particles.

In the embodiment of the disclosure, the surface of the second piezoresistive sensitive block has an uneven surface structure, and the uneven structure deforms under the action of external force, so that the resistance value of the resistor changes.

In the disclosed embodiment, the top and bottom of the pad are made of flexible material, wrapping the middle of the pad in the middle.

(III) advantageous effects

As can be seen from the above technical solutions, the dual-mode mechanical detection pad of the PS-type TKA prosthesis of the present disclosure has at least one or some of the following beneficial effects:

(1) the column can be prevented from being broken due to overlarge shearing stress on the column in a certain direction; meanwhile, a high-density array is obtained by customizing the density and the arrangement of the piezoresistive array, and a high-density and high-sensitivity pressure detection array can be finally obtained by means of the uneven surface structure of the sand paper mold;

(2) different from the hard shell used in the prior art, the cushion can better transmit the pressure on the surface of the pad to the internal pressure sensitive element, namely under the same external force action, the cushion has higher sensitivity in pressure reading and can detect more and more subtle stress conditions compared with the hard shell. Meanwhile, the bonding of the upper and lower layers of cushions is tighter than that of the hard shell, so that the dislocation of the whole cushion under the action of horizontal shearing force can be avoided;

(3) the whole system does not need external lead connection, can realize real wireless, and is more convenient to use in actual clinic;

(4) the production cost is not high, the formed product can be put into clinical use at a lower price, and the operation quality is improved on the premise of not increasing high economic burden on patients;

drawings

Fig. 1a is a schematic structural diagram of a PS-type gasket in the prior art.

Fig. 1b is a schematic diagram of a prior art CR-type gasket.

FIG. 2a is a schematic diagram of a multi-layer cavity structure of a PS-type detection pad in the prior art.

Fig. 2b is a schematic diagram of a prior art CR-type gasket.

Fig. 3 is a schematic structural view of a bimodal mechanical test pad of a PS type TKA prosthesis according to an embodiment of the present disclosure.

Fig. 4 is a schematic structural diagram of the detection system for the dual-mode mechanical detection pad using the PS-type TKA prosthesis according to the embodiment of the present disclosure.

Fig. 5 is a schematic flow chart of the preparation process of the piezoresistive strain array unit of the double-mold mechanical detection pad of the PS-type TKA prosthesis according to the embodiment of the present disclosure.

Fig. 6 is a schematic structural diagram of a piezoresistive strain array unit of a bi-modal mechanical test pad of a PS-type TKA prosthesis according to an embodiment of the present disclosure.

Fig. 7 is a cross-talk current schematic diagram of a piezoresistive strain array element of a bi-modal mechanical test pad of a PS-type TKA prosthesis according to an embodiment of the present disclosure.

Fig. 8 is a schematic diagram of zero potential scanning of piezoresistive strain array elements of a dual mode mechanical detection pad of a PS-type TKA prosthesis according to an embodiment of the present disclosure.

Fig. 9 is a schematic diagram of a piezoresistive strain array element of a bi-modal mechanical test pad of a PS-type TKA prosthesis with standard resistors added according to an embodiment of the present disclosure.

Fig. 10 is a schematic flow chart of the manufacturing process of the bi-modal mechanical testing liner shell of the PS-type TKA prosthesis according to the embodiment of the present disclosure.

Detailed Description

The utility model provides a bimodulus mechanics of PS type TKA prosthesis detects liner, can monitor the size and the distribution condition of artificial joint prosthesis stress that receives in real time, avoids artificial knee joint prosthesis's stress concentration through adjustment thickness.

In carrying out the present disclosure, the inventors have discovered that the currently clinically used liners can be roughly classified structurally into two types, posterior-stabilized (PS) type prosthetic liners and cruciate-retaining (CR) type prosthetic liners, the structures of which are shown in fig. 1a and 1b, wherein fig. 1a shows a PS type liner; figure 1b shows a CR type gasket. In practical clinical application, because the central position of the surface of the PS-type liner pad is provided with the upright post, the intercondylar notch matched with the bottom end of the femur can play the roles of connection and limitation, and therefore, the PS-type liner pad is more widely used in clinic. However, most of the current research results of pressure detection liners are based on CR-type prosthetic liners, and the stress detection of the liners is limited to the axial stress of the entire tibial plane, and only some of the mechanical detection liners based on PS-type prostheses do not bring the shear force of the central pillar into the detection range, as exemplified by the research results of the subject group of the professor David forschelet 2014, they designed a knee joint prosthetic pressure detection liner with a multi-layer cavity structure, as shown in fig. 2a and 2b, wherein fig. 2a shows a schematic diagram of the multi-layer structure, and fig. 2b shows an assembled finished diagram. Different from a single-layer printed circuit board, the strain gauge and the signal processing circuit in the structure are divided into two layers, two structural body cavities are arranged between the two layers of circuit boards, the cavities are located below the medial condyle and the lateral condyle of the femur, and meanwhile, the upper layer of each cavity is attached with one strain gauge, so that the structure can ensure that the strain gauges have enough strain space and better sense the pressure change condition. However, this structure does not detect the stress condition of the central column, and for the hard shell, the sensitivity of pressure transmission is poor, and because of the need of external lead wires, the whole shell has poor sealing performance, and is easy to be displaced integrally when receiving shearing force. Thus, the present disclosure proposes a dual-mode mechanical test pad for a PS-type TKA prosthesis to alleviate the above problems.

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

In an embodiment of the present disclosure, there is provided a dual-modulus mechanical test pad for a PS-type TKA prosthesis, as shown in fig. 3, the test pad comprising:

the upper surface comprises a central upright post, and a plurality of strain gauges are implanted in the central upright post;

the piezoresistive strain array unit is arranged at the joint of the middle part of the gasket and the lower surface of the top of the gasket and converts the transverse shearing force applied to the strain gauge and the vertical shearing stress applied to the detection gasket into electric signals; and

and the bottom of the liner is provided with a signal processing circuit for acquiring the electric signals and converting the electric signals into digital signals.

The piezoresistive strain array unit comprises an upper electrode structure layer, a lower electrode structure layer and a piezoresistive sensitive layer positioned between the upper electrode structure layer and the lower electrode structure layer; forming a three-layer sandwich structure.

The piezoresistive sensitive layer comprises a strain array and a piezoresistive array;

the signal processing circuit comprises an array scanning circuit for connecting and scanning the strain array and the piezoresistive array.

The strain array comprises a plurality of first piezoresistive sensitive blocks which are respectively connected with the plurality of strain gauges; when the central upright post is subjected to transverse shear stress, the strain gauge deforms, so that the array scanning circuit obtains a first electric signal reflecting the transverse shear stress applied to the central upright post;

the piezoresistive array comprises a plurality of second piezoresistive sensitive blocks, and when the second piezoresistive sensitive blocks receive vertical shear stress, the second piezoresistive sensitive blocks deform, so that the array scanning circuit obtains a second electric signal which reflects the vertical shear stress on the detection liner;

in the disclosure, the middle part of the pad is integrally in a soft plate shape, copper foil is used as an electrode contact point of the piezoresistive strain array unit and a lead wire for connecting an electrode, the tail end of the piezoresistive strain array unit is led out through a gold finger, metal wires for connecting rows and columns of the piezoresistive strain array unit are distributed on different layers, a piezoresistive block is pressed in the middle, and an electric signal is led out by using a metal electrode site.

As shown in fig. 3, the uppermost layer of the sensing mat includes a central pillar, in which a number of strain gauges are implanted for sensing horizontal shear stress; the middle layer is provided with a high-density piezoresistive array for detecting axial shear stress; the last layer is a signal acquisition and data transmission circuit.

In the embodiment of the disclosure, the architecture of the whole detection system for performing the dual-mode mechanical detection of the TKA prosthesis by using the detection pad is shown in fig. 4, the piezoresistive strain array is a mechanical detection element, mechanical quantity is converted into electrical quantity, and sampling and extraction are performed by using a scanning circuit. The whole scanning circuit consists of a microprocessor, a switch array and an operational amplifier, wherein the microprocessor outputs corresponding pulse signals to open and close the switch array, each closed row is a target row, and the change condition of each point in the row can be reflected only by scanning the output voltage at the tail end of each column. The pressure stress distribution display device is characterized in that the pressure stress distribution display device is used for converting the sampling of an ADC (analog to digital converter) into a digital signal and sending the digital signal back to a microprocessor circuit, then starting Bluetooth transmission and sending the digital signal to a computer end, and the computer end receives data through a Bluetooth receiving module and sends the data to an upper computer for pressure stress distribution display.

In an embodiment of the present disclosure, there is also provided a method for manufacturing the piezoresistive strain array unit, as shown in fig. 5, the method includes:

firstly, making a structure layer with an electrode, firstly, spin-coating a layer of PDMS (polydimethylsiloxane) or a rubber material with the elastic modulus similar to that of PDMS on a substrate (silicon, glass or stainless steel), heating and curing, then sputtering a metal layer (which can be Cr, Au or Al) with a certain thickness on the layer of film to be used as an electrode layer, photoetching and corroding electrode sites through a mask plate, simultaneously using a gel layer as a protective layer of the electrode, and finally stripping from the substrate;

and (b) manufacturing a piezoresistive sensitive layer, wherein a pressure sensitive nano composite material (such as carbon nano tube-PDMS, graphene-PDMS or a rubber material mixed with metal particles) is used as the piezoresistive sensitive material, a layer of pressure sensitive material is firstly coated on a mould in a spinning mode and is subjected to thermosetting, then the mask plate in the previous step is subjected to photoetching corrosion to obtain a piezoresistive sensitive block, and then the sensitive unit is peeled off from the mould. The die used here needs to have an uneven surface structure (such as P800 and P1000 type abrasive paper), the surface of the pressure-sensitive material coated in this way is also uneven, and the uneven structure is deformed under the action of external force, so that the resistance value of the resistor is changed, and meanwhile, the sensitivity of the piezoresistive array can also be improved;

and (c) manufacturing a filling layer of the piezoresistive sensitive layer, namely, firstly, coating a flexible film on the mould in the second step in a rotating mode to serve as an intermediate isolating layer, and cutting the isolating layer by using a hard mask after thermal curing. The fourth step is to stack an intermediate spacer layer between the top and bottom layers and fill the composite sensing element in the indents of the spacer layer with its abnormally shaped surface structures facing in the same direction.

The last step (d) is to bond the upper structural layer to the lower two layers using a gel and to thermoset the device. The piezoresistive array with the sandwich structure can be obtained through the steps, partial materials are selected as examples, and the whole process flow is shown as the following figures:

in the present disclosure, the whole array is made into a flexible board, copper foil is used as an electrode contact point and a lead wire for connecting electrodes, and the tail end is led out through a gold finger, so that the whole circuit design is shown in fig. 3, metal wires for connecting rows and columns are distributed on different layers, a piezoresistive block is pressed in the middle, and an electrical signal is led out by using a metal electrode site.

In a commonly used scan circuit, crosstalk current interference from many sources is accompanied, for example, a 3 × 3 array is taken as an example, crosstalk current in the array is as shown in fig. 7, and it can be seen from the schematic diagram that when the system scans to R12 in the second row in the array, only the current represented by the dotted line 2 with an arrow ideally flows through R12, but the current actually flowing through R11, R21 and R22 also flows out along the path of the solid line 1 with an arrow, and the same solid line 3 with an arrow flowing through R13, R23, R22 and R32 flows out from the output end of the second column, and such currents are collectively referred to as crosstalk current. In practical situations, crosstalk currents caused by different paths are still many, which causes that signals detected in a scanning circuit do not only include signals of a target node, and for application scenarios with high accuracy requirements, the scanning mode is difficult to meet requirements.

The scanning circuit in the present disclosure uses a zero potential method to scan, and connects the end of each column in the array to the negative input terminal of the operational amplifier, and connects the output terminal of the operational amplifier through the feedback resistor, so that the operational amplifier operates under a deep negative feedback condition, as shown in fig. 8. Meanwhile, the positive input end of the operational amplifier is grounded, and the voltages at the two input ends of the operational amplifier are approximately equal according to the basic principle of virtual short and virtual disconnection, so that the negative input end is approximately grounded. Taking the path shown by the solid line 3 with an arrow in fig. 7 as an example, since the negative input terminal is approximately grounded, the current will be directly output from the output end of the third column after flowing through R13, and will not flow to R23, R22, and R32, and will not affect the scanning of R12, thereby it can be shown that the method can greatly avoid the influence of crosstalk current at each site between arrays, and improve the accuracy of piezoresistive array scanning.

In addition, a standard resistor with constant resistance is added at the tail end of each column, so that the relation between input and output voltages can be converted into the relation between the voltage of the piezoresistive block and the voltage of the standard row, the measurement accuracy change caused by the fluctuation of the input voltage can be effectively avoided, and the circuit is as shown in fig. 9.

The difference from the circuit of fig. 8 is that fig. 9 adjusts the resistor of the third row in the circuit to be the standard resistor with constant resistance, and scans the target resistor R_ijIn the process of (3), the relationship between the input voltage, the output voltage and the resistance is as follows:

rf in the formula is a feedback resistor of the operational amplifier, and it can be seen from the formula that when Vin fluctuates, if an accurate input voltage value cannot be accurately detected in time, the scanned point resistance value is extremely inaccurate. After the standard row resistance is introduced, the relation between the standard resistance and the voltage meets the following formula:

by combining the above two equations, the influence of the input voltage on the detection result can be eliminated exactly, so that a more accurate scanning result can be obtained, and the target resistance calculation expression is as follows.

The shell is made of soft materials, a model of the whole knee joint prosthesis is firstly drawn through 3D modeling software, the shell is poured through the model making mold, and the making process of the whole shell is shown in the following figure 10: wherein (a) represents the fabrication of a cast mold. (b) Showing the upper and lower portions of the housing being cast through the mold. (c) Representing the attachment of a piezoresistive array to a single side housing surface. (d) The upper and lower shells are heated and bonded together, and the piezoresistive array is wrapped in the middle layer.

So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It is to be noted that, in the attached drawings or in the description, the implementation modes not shown or described are all the modes known by the ordinary skilled person in the field of technology, and are not described in detail. Further, the above definitions of the various elements and methods are not limited to the various specific structures, shapes or arrangements of parts mentioned in the examples, which may be easily modified or substituted by those of ordinary skill in the art.

From the above description, those skilled in the art should clearly recognize the dual-mode mechanical test pad of the PS-type TKA prosthesis of the present disclosure.

In summary, the disclosure provides a dual-mode mechanical detection pad for various PS-type TKA prostheses, which can detect the stress conditions of knee joint prostheses in TKA surgery, including the axial stress on the lateral plane of the tibia and the horizontal shear stress on the central upright post, by two different detection methods of piezoresistive array strain. The piezoresistive array adopted by the design has a large pressure detection range, and can detect the pressure intensity distribution condition received by more sites on the whole tibial plane. Compared with the existing TKA pressure detection gaskets, the design has the greatest advantage that the high-density axial stress detection of the gasket plane is used for detecting the horizontal shearing force of the central upright post, and the stress concentration is avoided by detecting the stress of the structure and adjusting the position of the prosthesis, so that the service life of the prosthesis can be greatly prolonged. Meanwhile, the sensitive element and the processing circuit of the gasket are completely sealed in the PDMS cushion, and an external lead is not needed, so that the gasket is convenient to use clinically. Meanwhile, the production cost is low, and the operation quality can be improved on the basis of not increasing the economic burden of a patient.

It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure.

And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.

In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.

Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Also in the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware.

The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.

Claims

1. A dual-modulus mechanical test pad for a PS-type TKA prosthesis, comprising:

2. The dual modulus mechanical test pad of a PS-type TKA prosthesis of claim 1, the piezoresistive strain array unit comprising an upper electrode structure layer, a lower electrode structure layer, and a piezoresistive sensitive layer between the upper and lower electrode structure layers.

3. The dual modulus mechanical test pad of a PS-type TKA prosthesis of claim 2, the piezoresistive sensitive layer comprising a strain array and a piezoresistive array.

4. The dual modulus mechanical detection pad of a PS type TKA prosthesis of claim 3, the signal processing circuitry comprising array scanning circuitry for connecting and scanning the strain array and piezoresistive array.

5. The dual modulus mechanical test pad of a PS-type TKA prosthesis of claim 4, the strain array comprising a plurality of first piezoresistive sensitive blocks respectively connected to the plurality of strain gages; when the central upright post is subjected to transverse shear stress, the strain gauge can deform, so that the array scanning circuit obtains a first electric signal reflecting the transverse shear stress on the central upright post.

6. The dual-modal mechanical test pad of a PS-type TKA prosthesis of claim 4, the piezoresistive array comprising a plurality of second piezoresistive sensitive blocks which deform when subjected to vertical shear stress, thereby enabling the array scan circuit to obtain a second electrical signal which reflects the vertical shear stress to which the test pad is subjected.

7. The dual-mode mechanical detection pad of the PS-type TKA prosthesis according to claim 1, wherein the pad is integrally soft in middle, copper foil is used as electrode contact points of the piezoresistive strain array unit and a lead wire for connecting electrodes, the tail end of the pad is led out through a gold finger, metal wires connecting rows and columns of the piezoresistive strain array are distributed on different layers, and electric signals are led out through metal electrode sites.

8. The dual-mode mechanical detection pad of the PS-type TKA prosthesis according to claim 6, wherein the second piezoresistive sensitive block is made of any one of carbon nanotube-PDMS, graphene-PDMS or a rubber material mixed with metal particles.

9. The dual-mode mechanical detection pad of the PS-type TKA prosthesis according to claim 8, wherein the surface of the second piezoresistive sensitive block is provided with an uneven surface structure, and the uneven structure is deformed under the action of external force, so that the resistance value of the resistor is changed.

10. The dual-modulus mechanical testing spacer for a PS-type TKA prosthesis according to claim 1, wherein the top and bottom spacer portions are made of flexible material, and the middle spacer portion is wrapped in the middle.