Data Acquisition System and Method Based on Planar Knee Joint Pressure Testing Pad

Abstract

This application provides a data acquisition system and method based on a planar knee joint pressure test pad, belonging to the field of knee joint detection technology. The system includes: a planar knee joint pressure test pad, with an embedded pressure sensor array for acquiring initial knee joint pressure data; a knee joint model construction module for constructing a corresponding three-dimensional surface model based on three-dimensional scan data of the target knee joint, and determining the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array; and a data compensation module for compensating the initial knee joint pressure data based on the virtual surface depth, a preset compensation intensity, and a preset sensitivity coefficient to obtain accurate knee joint pressure data. This application enables the planar knee joint pressure test pad to achieve soft tissue balance measurement accuracy equivalent to that of a curved test pad, while retaining the versatility advantages of the planar test pad.

Description

Technical Field

[0001] This application relates to the field of knee joint detection technology, and in particular to a data acquisition system and method based on a planar knee joint pressure test pad. Background Technology

[0002] In the field of joint replacement surgery, accurate assessment of surgical outcomes is crucial for postoperative recovery and joint function. Pressure measurement pads, as an effective assessment tool, have long been widely used in such surgeries. They provide surgeons with data on joint contact pressure, thereby assisting them in adjusting and optimizing surgical plans to ensure good function and durability after joint replacement.

[0003] In existing technologies, curved pressure test pads and planar pressure test pads are two common types. Curved pressure test pads can better conform to the anatomical shape of the joint, thus more realistically reflecting the joint contact pressure. However, their manufacturing process requires matching various curvature specifications, which not only significantly increases production costs but also necessitates frequent replacement of components of different specifications during surgery, causing considerable inconvenience to the surgical procedure. On the other hand, while planar pressure test pads can capture the actual contact pressure of the joint to some extent, their rigid contact characteristics often lead to the loss of edge signals, making it impossible to completely and accurately present the joint pressure distribution. Furthermore, most current virtual compensation technologies are based on linear interpolation algorithms, which have significant shortcomings in reconstructing the mechanical properties of joint curved surface contact, making it difficult to meet the high precision requirements of clinical surgery.

[0004] Therefore, improving the accuracy of planar pressure test pads in measuring knee joint pressure is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a data acquisition system and method based on a planar knee joint pressure test pad to solve the above-mentioned problems.

[0006] To achieve the above objectives, firstly, this application proposes a data acquisition system based on a planar knee joint pressure test pad, the system comprising:

[0007] A planar knee joint pressure test pad, wherein the planar knee joint pressure test pad is embedded with a pressure sensor array, the pressure sensor array being used to collect initial knee joint pressure data;

[0008] A knee joint model construction module is used to construct a corresponding three-dimensional surface model based on the three-dimensional scanning data of the target knee joint, and to determine the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array.

[0009] The data compensation module is used to compensate the initial knee joint pressure data based on the virtual surface depth, preset compensation intensity, and preset sensitivity coefficient to obtain real knee joint pressure data.

[0010] In some implementations, determining the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array includes:

[0011] The three-dimensional curved surface model and the geometric model of the planar knee joint pressure test pad are registered in three-dimensional space to align the model coordinate system with the test pad coordinate system.

[0012] Using each sensing unit in the pressure sensor array as a reference, a ray is projected onto the three-dimensional curved surface model along the normal direction of each sensing unit, and the intersection point of each ray with the surface of the three-dimensional curved surface model is determined.

[0013] Calculate the vertical distance from each intersection point to the plane where the pressure sensor array is located, and use the vertical distance as the virtual surface depth of the corresponding sensing unit.

[0014] In some embodiments, the system further includes an offset determination module, the offset determination module being used for:

[0015] The preset osteotomy plane is determined based on the aforementioned three-dimensional surface model;

[0016] Calculate the surface distance from the preset osteotomy plane to each point on the leg bone along the normal direction of the preset osteotomy plane;

[0017] The surface distance is used as a deformation variable, and the target pressure distribution is calculated based on Hooke's law;

[0018] The target pressure distribution is determined based on the target pressure distribution and the preset area of ​​each sensing unit;

[0019] The actual knee joint pressure data and the target pressure distribution are compared to determine whether the osteotomy has deviated.

[0020] In some implementations, comparing the actual knee joint pressure data with the target pressure distribution to determine whether the osteotomy has deviated includes:

[0021] Extract the true pressure center location, true left-side pressure, true right-side pressure, and true left-right pressure difference from the actual knee joint pressure data; and

[0022] Extract the target pressure center position, the pressure on the left side of the target, the pressure on the right side of the target, and the pressure difference between the left and right sides of the target pressure distribution.

[0023] When the actual left pressure is less than the target left pressure and the actual right pressure is less than the target right pressure, or when the actual left pressure is greater than the target left pressure and the actual right pressure is greater than the target right pressure, the osteotomy position is determined to be offset.

[0024] When the pressure offset between the actual left-right pressure difference and the target left-right pressure difference is greater than a preset threshold, the osteotomy angle is determined to be offset.

[0025] In some embodiments, the system further includes an intraoperative correction module, which, when determining osteotomy position deviation, is used to determine the target pad thickness based on the pressure deviation between the actual left-right pressure difference and the target left-right pressure difference, and a preset conversion coefficient.

[0026] When determining the deviation of the osteotomy angle, the intraoperative correction module is used to calculate the compensation angle based on the center offset between the actual pressure center position and the target pressure center position.

[0027] In some embodiments, the offset determination module is further configured to:

[0028] The target pressure distribution was numerically verified using finite element analysis to generate an allowable error range.

[0029] The step of comparing the actual knee joint pressure data with the target pressure distribution to determine whether the osteotomy has deviated includes:

[0030] The actual knee joint pressure data is compared with the allowable error range to determine whether the osteotomy has deviated.

[0031] In some implementations, the step of numerically verifying the target pressure distribution through finite element analysis to generate an allowable error range includes:

[0032] Import the three-dimensional curved surface model, the geometric model of the planar knee joint pressure test pad, and the position information of the preset osteotomy plane into the finite element analysis software;

[0033] Based on the finite element analysis software, corresponding material parameters are set for each key anatomical structure in the three-dimensional curved surface model and the geometric model of the planar knee joint pressure test pad;

[0034] The target pressure distribution is converted into an equivalent normal force, and the equivalent normal force is applied to the three-dimensional curved surface model to obtain the simulated pressure distribution of the geometric model of the planar knee joint pressure test pad;

[0035] Based on the target pressure distribution and the simulated pressure distribution, an allowable error range is generated.

[0036] In some implementations, generating an allowable error range based on the target pressure distribution and the simulated pressure distribution includes:

[0037] Calculate the pressure difference between the target pressure distribution and the simulated pressure distribution in each sensing unit;

[0038] The confidence interval of the pressure difference within a preset range is used as the upper limit of the node error, and the allowable error range is formed based on the envelope of all the node error upper limits.

[0039] Secondly, this application proposes a data acquisition method based on a planar knee joint pressure test pad, applied to the data acquisition system based on a planar knee joint pressure test pad as described above, the method comprising:

[0040] Acquire initial knee joint pressure data collected by the pressure sensor array, as well as a three-dimensional surface model of the target knee joint;

[0041] Determine the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array;

[0042] Based on the virtual surface depth, preset compensation intensity, and preset sensitivity coefficient, the initial knee joint pressure data is compensated to obtain the real knee joint pressure data.

[0043] In some implementations, determining the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array includes:

[0044] The three-dimensional curved surface model and the geometric model of the planar knee joint pressure test pad are registered in three-dimensional space to align the model coordinate system with the test pad coordinate system.

[0045] Using each sensing unit in the pressure sensor array as a reference, a ray is projected onto the three-dimensional curved surface model along the normal direction of each sensing unit, and the intersection point of each ray with the surface of the three-dimensional curved surface model is determined.

[0046] Calculate the vertical distance from each intersection point to the plane where the pressure sensor array is located, and use the vertical distance as the virtual surface depth of the corresponding sensing unit.

[0047] Compared with the prior art, the beneficial effects of this application include:

[0048] This application achieves a virtual surface depth measurement accuracy equivalent to that of a planar knee pressure test pad by deeply coupling a planar knee pressure test pad with a three-dimensional surface model of the patient-specific target knee joint. Using preoperative scan data, the virtual surface depth is calculated on each sensing unit, and then nonlinear compensation is applied to the initial pressure data collected by the planar knee pressure test pad. This allows the planar knee pressure test pad to achieve the same soft tissue balance measurement accuracy as a flexure test pad without increasing the manufacturing cost or the number of surgical replacements. It also retains the versatility of the planar test pad, effectively solving the technical problems of existing flexure test pads, such as numerous specifications, high cost, and missing edge signals and measurement distortion. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0050] Figure 1 This is a schematic diagram of the functional modules of a data acquisition system based on a planar knee joint pressure test pad in one embodiment.

[0051] Figure 2 This is a schematic diagram of the functional modules of a data acquisition system based on a planar knee joint pressure test pad in another embodiment;

[0052] Figure 3 This is a schematic diagram of the osteotomy angle offset from the normal viewpoint of the osteotomy plane in one embodiment.

[0053] Figure 4 This is a schematic diagram showing the osteotomy angle without offset from the normal view of the osteotomy plane in one embodiment;

[0054] Figure 5 This is a schematic diagram of the effect of the finite element model generated by Abaqus in one embodiment;

[0055] Figure 6 This is a schematic diagram illustrating the mesh generation of the geometric model of a planar knee joint pressure test pad using Abaqus as an example in one embodiment;

[0056] Figure 7 This is a schematic diagram illustrating the application of the equivalent normal force to a three-dimensional surface model using Abaqus as an example in one embodiment;

[0057] Figure 8 This is a schematic diagram of the simulated pressure distribution of a planar knee joint pressure test pad obtained using Abaqus as an example in one embodiment;

[0058] Figure 9This is a schematic diagram of the overall process of a data acquisition method based on a planar knee joint pressure test pad in one embodiment.

[0059] The following are the definitions of the reference numerals: 100, Data acquisition system based on planar knee joint pressure test pad; 1, Planar knee joint pressure test pad; 2, Knee joint model construction module; 3, Data compensation module; 4, Offset determination module; 5, Intraoperative correction module. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0061] All terms used in this application (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0062] For example, the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.

[0063] For example, the terms "comprising" or "including" used in this application indicate the presence of features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0064] As mentioned earlier, curved pressure test pads and planar pressure test pads are two common types in the prior art. Curved pressure test pads can better conform to the anatomical shape of the joint, thus more realistically reflecting the joint contact pressure. However, their manufacturing process requires matching various curvature specifications, which not only significantly increases production costs but also necessitates frequent replacement of components of different specifications during surgery, causing considerable inconvenience. On the other hand, while planar pressure test pads can capture the actual contact pressure of the joint to some extent, their rigid contact characteristics often lead to the loss of edge signals, making it impossible to fully and accurately present the joint pressure distribution. Furthermore, most current virtual compensation technologies are based on linear interpolation algorithms, which have significant shortcomings in reconstructing the mechanical properties of joint curved surfaces, making it difficult to meet the high precision requirements of clinical surgery. Therefore, how to improve the measurement accuracy of knee joint pressure using planar pressure test pads is a pressing technical problem that needs to be solved. To address this, this application proposes a data acquisition system and method based on a planar knee joint pressure test pad. This system enables the planar knee joint pressure test pad to achieve soft tissue balance measurement accuracy equivalent to that of the flexure test pad without increasing the manufacturing cost and number of surgical replacements. At the same time, it retains the versatility advantage of the planar test pad and effectively solves the technical problems of the existing flexure test pads having numerous specifications and high costs, as well as the lack of edge signals and measurement distortion of the planar knee joint pressure test pad.

[0065] like Figure 1 As shown in the figure, this application provides a data acquisition system 100 based on a planar knee joint pressure test pad. The system 100 includes: a planar knee joint pressure test pad 1, a knee joint model construction module 2, and a data compensation module 3.

[0066] The planar knee joint pressure test pad 1 in this embodiment is flat and is a force-sensitive pad inserted between the tibial osteotomy surface and the distal femur during surgery. The planar knee joint pressure test pad 1 is embedded with a pressure sensor array, which is a two-dimensional matrix composed of several miniature sensing units arranged in rows and columns. It can convert the "contact pressure" of the joint surface into a quantifiable electrical signal, i.e., the initial knee joint pressure data.

[0067] In this embodiment, the knee joint model construction module 2 is used to construct a corresponding three-dimensional surface model based on the three-dimensional scanning data of the target knee joint, and to determine the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array.

[0068] Specifically, 3D scan data refers to three-dimensional image data of a patient's target knee joint obtained through medical imaging technologies such as CT (Computed Tomography) or MRI (Magnetic Resonance Imaging), containing information about structures such as bones and soft tissues. In some implementations, 3D scan data can be imported using medical image processing software, and key anatomical structures of the knee joint can be extracted using algorithms such as threshold segmentation and region growing to generate a 3D surface model. Key anatomical structures include the femur, tibia, ligaments, and meniscus.

[0069] As a feasible implementation for determining the virtual surface depth of a 3D surface model within each sensing unit of a pressure sensor array, the 3D surface model and the geometric model of a planar knee joint pressure test pad 1 can be registered in 3D space to align the model coordinate system with the test pad coordinate system. For example, corresponding marker points can be added to the 3D surface model and the planar knee joint pressure test pad 1, and registration can be performed based on these marker points. Using each sensing unit in the pressure sensor array as a reference, rays are projected onto the 3D surface model along the normal direction of each sensing unit, and the intersection points of each ray with the surface of the 3D surface model are determined. For example, a corresponding normal vector can be defined for each sensing unit, and rays are projected along the direction of the corresponding normal vector using each sensing unit as a reference, and a ray tracing algorithm is used to determine the intersection points of each ray with the surface of the 3D surface model. The vertical distance from each intersection point to the plane where the pressure sensor array is located is calculated, and this vertical distance is used as the virtual surface depth of the corresponding sensing unit. This embodiment can effectively simulate the curved surface contact characteristics of the knee joint through precise registration, ray projection, and depth calculation, and determine the virtual curved surface depth corresponding to each sensing unit so as to compensate the initial knee joint pressure data according to the virtual curved surface depth.

[0070] In this embodiment, the data compensation module 3 is used to compensate the initial knee joint pressure data based on the virtual surface depth, preset compensation intensity, and preset sensitivity coefficient to obtain real knee joint pressure data.

[0071] Specifically, data compensation module 3 is used based on The actual knee joint pressure data were calculated. For the first The actual knee joint pressure data after compensation by each sensing unit For the first Initial knee joint pressure data collected by each sensing unit For the first The virtual surface depth corresponding to the location of each sensing unit To preset the compensation strength, The preset sensitivity coefficient, and , .

[0072] It is important to understand the preset compensation strength. Before surgery, a calibration experiment is conducted to substitute the "true pressure" measured using a curved pressure test pad and the "original pressure" measured using a flat test pad back into the formula. The solution The optimal value, after compensation The result obtained using the curved test pad showed the smallest error. Similarly, through experimental comparison, the preset sensitivity coefficient was found to be... The compensation curve matches the true surface best when the value is between 0.1 and 0.2. The larger, Start by enlarging from the smallest size; The smaller the value, the more it will be magnified only for very steep depressions.

[0073] The data acquisition system based on the planar knee joint pressure test pad 1 proposed in this application deeply couples the planar knee joint pressure test pad 1 with the three-dimensional curved surface model of the patient-specific target knee joint. The virtual curved surface depth is calculated on each sensing unit using preoperative scanning data, and then nonlinear compensation is performed on the initial pressure data collected by the planar knee joint pressure test pad 1 accordingly. Thus, without increasing the manufacturing cost of the curved surface test pad or the number of surgical replacements, the planar knee joint pressure test pad 1 achieves soft tissue balance measurement accuracy equivalent to that of the curved surface test pad, while retaining the versatility advantage of the planar test pad. This effectively solves the technical problems of existing curved surface test pads having many specifications, high cost, and missing edge signals and measurement distortion of the planar knee joint pressure test pad.

[0074] In one embodiment, such as Figure 2 As shown, the data acquisition system 100 based on the planar knee joint pressure test pad 1 also includes an offset determination module 4.

[0075] In this embodiment, the offset determination module 4 is a functional module in the system used to analyze and determine whether the osteotomy position has shifted during knee replacement surgery.

[0076] Specifically, a preset osteotomy plane can be determined based on the three-dimensional surface model. This preset osteotomy plane refers to an osteotomy plane pre-set according to the surgical plan or standard surgical procedure. The surface distance from the preset osteotomy plane to various points on the leg bone is calculated along the normal direction of the preset osteotomy plane. This surface distance is used as a deformation variable, and the target pressure distribution is calculated based on Hooke's law. For example, based on... The target pressure distribution was calculated, where, Corresponding target pressure distribution The corresponding deformation, i.e., the surface distance from the preset osteotomy plane to each point on the leg bone, is represented by E, which is the elastic modulus of the material simulating the knee joint. This value is constant when the material is considered a perfectly elastic body. Based on the target pressure distribution and the preset area of ​​each sensing unit, the target pressure distribution is determined. For example, the target pressure distribution is obtained by using the preset area of ​​each sensing node to represent the target pressure distribution corresponding to each sensing unit. The actual knee joint pressure data is compared with the target pressure distribution to determine whether the osteotomy position has deviated. Through the deviation determination module 4, the accuracy of the osteotomy position in knee replacement surgery can be effectively evaluated, providing real-time feedback to the surgeon and thus improving the success rate of the surgery.

[0077] As a feasible implementation method for comparing the actual knee joint pressure data with the target pressure distribution to determine whether the osteotomy has deviated, the following can be extracted from the actual knee joint pressure data: the actual pressure center position, the actual left-side pressure, the actual right-side pressure, and the actual left-right pressure difference; and the target pressure center position, the target left-side pressure, the target right-side pressure, and the target left-right pressure difference. The actual pressure center position refers to the location of the point with the highest pressure in the actual knee joint pressure data. The actual left-side pressure refers to the average pressure value within a certain area to the left of the actual pressure center position (e.g., 20% of the sensor array width). The actual right-side pressure refers to the average pressure value within the corresponding area to the right of the actual pressure center position. The actual left-right pressure difference is the difference between the actual left-side pressure and the actual right-side pressure, reflecting the symmetry of the pressure distribution. The target pressure center position refers to the location of the point with the highest pressure in the target pressure distribution. The target left-side pressure refers to the average pressure value within a certain area to the left of the target pressure center position (e.g., 20% of the sensor array width). The target right-side pressure refers to the average pressure value within the corresponding area to the right of the target pressure center position. The pressure difference between the left and right sides of the target refers to the difference between the pressure on the left side and the pressure on the right side of the target, reflecting the symmetry of the pressure distribution.

[0078] When the actual left-side pressure is less than the target left-side pressure and the actual right-side pressure is less than the target right-side pressure, or when the actual left-side pressure is greater than the target left-side pressure and the actual right-side pressure is greater than the target right-side pressure, the osteotomy position is determined to be off.

[0079] Specifically, when the actual left-side pressure is less than the target left-side pressure, and the actual right-side pressure is less than the target right-side pressure, it is determined that the osteotomy position has shifted away from the center of the knee joint relative to the preset osteotomy plane. When the actual left-side pressure is greater than the target left-side pressure, and the actual right-side pressure is greater than the target right-side pressure, it is determined that the osteotomy position has shifted closer to the center of the knee joint relative to the preset osteotomy plane.

[0080] When the pressure offset between the actual left-right pressure difference and the target left-right pressure difference exceeds a preset threshold (e.g., 5N), the osteotomy angle offset is determined. Figure 3 As shown. Conversely, it is determined that there is no osteotomy angle deviation, as shown. Figure 4 As shown. It can be understood that if, when determining osteotomy position deviation, the pressure deviation between the actual left-right pressure difference and the target left-right pressure difference is less than or equal to a preset threshold, then only osteotomy position deviation is determined to exist. If, when determining osteotomy position deviation, the pressure deviation between the actual left-right pressure difference and the target left-right pressure difference is greater than a preset threshold, then both osteotomy position deviation and osteotomy angle deviation are determined to exist simultaneously.

[0081] In some implementations, the offset determination module 4 is also used to: numerically verify the target pressure distribution through finite element analysis and generate an allowable error range, which refers to the maximum allowable deviation range of the actual knee joint pressure data. For example, the actual pressure center position can be offset to the right by 5mm-10mm and basically located within ±2mm of the target pressure center position in the vertical direction, and the actual right-side pressure can be 20N ±5N greater than the actual left-side pressure.

[0082] Specifically, the three-dimensional curved surface model, the geometric model of the planar knee joint pressure test pad 1, and the position information of the preset osteotomy plane can be imported into finite element analysis software (such as Abaqus, ANSYS, etc.). Taking Abaqus as an example, the generated finite element model looks like this: Figure 5 As shown. Based on the finite element analysis software, corresponding material parameters are set for each key anatomical structure in the three-dimensional curved surface model and the geometric model of the planar knee joint pressure test pad 1. For example, since the mechanical strength of the leg bone is much greater than that of the planar knee joint pressure test pad 1, the leg bone can be treated as a rigid body. The material parameters of the planar knee joint pressure test pad 1 can be set as follows: elastic modulus of 6 MPa, Poisson's ratio of 0.495, and 1.2 MPa. The density. For example... Figure 6 As shown, the geometric model of the planar knee joint pressure test pad 1 is meshed, and the total number of mesh nodes can be controlled to around 30,000 to meet the simulation requirements. The target pressure distribution is converted into an equivalent normal force, and as shown... Figure 7 As shown, the equivalent normal force is applied to the three-dimensional curved surface model to obtain the simulated pressure distribution of the geometric model of the planar knee joint pressure test pad 1, as follows. Figure 8 As shown. In some implementations, the sum of the forces distributed in the normal direction of the target pressure distribution can be used as the equivalent normal force. Furthermore, an allowable error range is generated based on the target pressure distribution and the simulated pressure distribution.

[0083] In some implementations, the pressure difference between the target pressure distribution and the simulated pressure distribution at each sensing unit can be calculated, and the statistical distribution (such as standard deviation, confidence interval, etc.) of the pressure difference corresponding to each sensing unit can be determined to generate an allowable error range. Specifically, the pressure difference between the target pressure distribution and the simulated pressure distribution at each sensing unit can be calculated; the confidence interval of the pressure difference within a preset range (such as 95%) can be used as the node error upper limit, and the allowable error range can be formed based on the envelope of all the node error upper limits. Here, the envelope refers to an "error upper limit surface" that connects the node error upper limits corresponding to each sensing unit in space in a two-dimensional array, i.e., the allowable error range.

[0084] As another feasible implementation of comparing the actual knee joint pressure data with the target pressure distribution to determine whether the osteotomy has deviated, the actual knee joint pressure data can be compared with the allowable error range to determine whether the osteotomy has deviated.

[0085] In some implementations, the allowable error range can be rendered as a dynamic mask grayscale image, and the real knee joint pressure data can be mapped as a pressure grayscale distribution image. In the dynamic mask grayscale image and the pressure grayscale distribution image, the larger the pressure value, the smaller the grayscale value. The dynamic mask grayscale image and the pressure grayscale distribution image are compared at the pixel level to determine whether the osteotomy has been offset.

[0086] Specifically, when the gray value on the left side of the pressure grayscale distribution map is greater than the gray value on the left side of the dynamic mask grayscale map, and the gray value on the right side of the pressure grayscale distribution map is greater than the gray value on the right side of the dynamic mask grayscale map, or when the gray value on the left side of the pressure grayscale distribution map is less than the gray value on the left side of the dynamic mask grayscale map, and the gray value on the right side of the pressure grayscale distribution map is less than the gray value on the right side of the dynamic mask grayscale map, the osteotomy position is determined to be off.

[0087] Specifically, when the grayscale value on the left side of the pressure grayscale distribution map is greater than that on the left side of the dynamic mask grayscale map, and the grayscale value on the right side of the pressure grayscale distribution map is greater than that on the right side of the dynamic mask grayscale map, it is determined that the osteotomy position has shifted away from the center of the knee joint relative to the preset osteotomy plane. When the grayscale value on the left side of the pressure grayscale distribution map is less than that on the left side of the dynamic mask grayscale map, and the grayscale value on the right side of the pressure grayscale distribution map is less than that on the right side of the dynamic mask grayscale map, it is determined that the osteotomy position has shifted closer to the center of the knee joint relative to the preset osteotomy plane.

[0088] An osteotomy angle shift is determined when the grayscale offset between the left and right grayscale differences in the pressure grayscale distribution image and the dynamic mask grayscale image exceeds a preset threshold. In other words, if the grayscale offset between the left and right grayscale differences in the pressure grayscale distribution image and the dynamic mask grayscale image is less than or equal to the preset threshold when determining osteotomy position shift, then only osteotomy position shift is determined to exist. If the grayscale offset between the left and right grayscale differences in the pressure grayscale distribution image and the dynamic mask grayscale image exceeds the preset threshold when determining osteotomy position shift, then both osteotomy position shift and osteotomy angle shift are determined to exist simultaneously.

[0089] Furthermore, the data acquisition system 100 based on the planar knee joint pressure test pad 1 also includes an intraoperative correction module 5.

[0090] When determining the displacement of the osteotomy position, the intraoperative correction module 5 is used to determine the pressure displacement based on the actual left-right pressure difference and the target left-right pressure difference. and preset conversion coefficients Determine the thickness of the target gasket. , ,in, The preset conversion coefficient can be pre-calculated through preoperative calibration experiments. When determining the osteotomy angle deviation, the intraoperative correction module 5 is used to calculate the compensation angle based on the center offset between the actual pressure center position and the target pressure center position. , ,in, The center offset, It is the straight-line distance between the farthest points of the medial and lateral condyles of the femur.

[0091] In the data acquisition system 100 based on the planar knee joint pressure test pad 1 proposed in this application embodiment, firstly, the offset determination module 4 can analyze real knee joint pressure data in real time and quickly identify deviations in osteotomy position and angle to guide intraoperative correction. This real-time feedback mechanism not only reduces waiting and adjustment time during surgery and speeds up the surgical process, but also reduces patient infection and other surgery-related risks by reducing unnecessary surgical operations. Secondly, the instant feedback provided by the intraoperative correction module 5 enables doctors to make quick decisions, reducing the number of intraoperative adjustments and additional material consumption, which not only improves surgical efficiency but also helps to reduce surgical costs. Thirdly, the target pressure distribution is numerically verified through finite element analysis to generate an allowable error range, providing a quantitative evaluation standard for the deviation between real knee joint pressure data and the target pressure distribution.

[0092] In one embodiment, such as Figure 9As shown, this application provides a data acquisition method based on a planar knee joint pressure test pad. The method is applied to the data acquisition system 100 based on a planar knee joint pressure test pad as described in any of the above embodiments or implementations. The method includes:

[0093] Step S10: Obtain the initial knee joint pressure data collected by the pressure sensor array, and the three-dimensional surface model corresponding to the target knee joint.

[0094] In this embodiment, the pressure sensor array is a two-dimensional matrix composed of several miniature sensing units arranged in rows and columns. It can convert the "contact pressure" of the joint surface into a quantifiable electrical signal, i.e., the initial knee joint pressure data. Three-dimensional scan data refers to the three-dimensional image data of the patient's target knee joint obtained through medical imaging technologies such as CT (Computed Tomography) or MRI (Magnetic Resonance Imaging), containing information about structures such as bones and soft tissues. In some implementations, medical image processing software can be used to import the three-dimensional scan data and extract key anatomical structures of the knee joint through algorithms such as threshold segmentation and region growing to generate a three-dimensional surface model. Key anatomical structures include the femur, tibia, ligaments, and meniscus.

[0095] Step S20: Determine the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array.

[0096] In some implementations, the three-dimensional curved surface model and the geometric model of the planar knee joint pressure test pad 1 can be registered in three-dimensional space to align the model coordinate system with the test pad coordinate system. For example, corresponding marker points can be added to the three-dimensional curved surface model and the planar knee joint pressure test pad 1, and registration can be performed based on the corresponding marker points. Using each sensing unit in the pressure sensor array as a reference, rays are projected onto the three-dimensional curved surface model along the normal direction of each sensing unit, and the intersection points of each ray with the surface of the three-dimensional curved surface model are determined. For example, a corresponding normal vector can be defined for each sensing unit, and rays are projected along the direction of the corresponding normal vector using each sensing unit as a reference, and the intersection points of each ray with the surface of the three-dimensional curved surface model are determined using a ray tracing algorithm. The vertical distance from each intersection point to the plane where the pressure sensor array is located is calculated, and the vertical distance is used as the virtual surface depth of the corresponding sensing unit. This implementation can effectively simulate the curved surface contact characteristics of the knee joint through accurate registration, ray projection, and depth calculation, and determine the virtual surface depth corresponding to each sensing unit to compensate the initial knee joint pressure data according to the virtual surface depth.

[0097] Step S30: Based on the virtual surface depth, preset compensation intensity, and preset sensitivity coefficient, the initial knee joint pressure data is compensated to obtain the real knee joint pressure data.

[0098] Specifically, based on The actual knee joint pressure data were calculated. For the first The actual knee joint pressure data after compensation by each sensing unit For the first Initial knee joint pressure data collected by each sensing unit For the first The virtual surface depth corresponding to the location of each sensing unit To preset the compensation strength, The preset sensitivity coefficient, and , .

[0099] It is important to understand the preset compensation strength. Before surgery, a calibration experiment is conducted to substitute the "true pressure" measured using a curved pressure test pad and the "original pressure" measured using a flat test pad back into the formula. The solution The optimal value, after compensation The result obtained using the curved test pad showed the smallest error. Similarly, through experimental comparison, the preset sensitivity coefficient was found to be... The compensation curve matches the true surface best when the value is between 0.1 and 0.2. The larger, Start by enlarging from the smallest size; The smaller the value, the more it will be magnified only for very steep depressions.

[0100] In the data acquisition method based on the planar knee joint pressure test pad 1 proposed in this application embodiment, the planar knee joint pressure test pad 1 is deeply coupled with the three-dimensional curved surface model of the patient-specific target knee joint. The virtual curved surface depth is calculated on each sensing unit using preoperative scanning data, and then nonlinear compensation is performed on the initial pressure data acquired by the planar knee joint pressure test pad 1 accordingly. Thus, without increasing the manufacturing cost of the curved surface test pad or the number of surgical replacements, the planar knee joint pressure test pad 1 achieves the same soft tissue balance measurement accuracy as the curved surface test pad, while retaining the versatility advantage of the planar test pad. This effectively solves the technical problems of the existing curved surface test pads having many specifications, high cost, and missing edge signals and measurement distortion of the planar knee joint pressure test pad.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0102] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the embodiments or implementations claimed above can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A data acquisition system based on a planar knee joint pressure test pad, characterized in that, The system includes: A planar knee joint pressure test pad, wherein the planar knee joint pressure test pad is embedded with a pressure sensor array, the pressure sensor array being used to collect initial knee joint pressure data; A knee joint model construction module is used to construct a corresponding three-dimensional surface model based on the three-dimensional scanning data of the target knee joint, and to determine the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array. A data compensation module is used to compensate the initial knee joint pressure data based on the virtual surface depth, a preset compensation intensity, and a preset sensitivity coefficient to obtain real knee joint pressure data; wherein, , For the first The actual knee joint pressure data after compensation by each sensing unit For the first Initial knee joint pressure data collected by each sensing unit For the first The virtual surface depth corresponding to the location of each sensing unit To preset the compensation strength, Preset sensitivity coefficient, preset compensation intensity The solution is obtained by substituting the actual knee joint pressure data measured with a curved pressure test pad and the initial knee joint pressure data measured with a flat knee joint pressure test pad back into the above formula through a preoperative calibration experiment. The optimal value, after compensation The result with the curved pressure test pad has the smallest error.

2. The data acquisition system based on a planar knee joint pressure test pad according to claim 1, characterized in that, Determining the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array includes: The three-dimensional curved surface model and the geometric model of the planar knee joint pressure test pad are registered in three-dimensional space to align the model coordinate system with the test pad coordinate system. Using each sensing unit in the pressure sensor array as a reference, a ray is projected onto the three-dimensional curved surface model along the normal direction of each sensing unit, and the intersection point of each ray with the surface of the three-dimensional curved surface model is determined. Calculate the vertical distance from each intersection point to the plane where the pressure sensor array is located, and use the vertical distance as the virtual surface depth of the corresponding sensing unit.

3. The data acquisition system based on a planar knee joint pressure test pad according to claim 1, characterized in that, The system further includes an offset determination module, which is used for: The preset osteotomy plane is determined based on the aforementioned three-dimensional surface model; Calculate the surface distance from the preset osteotomy plane to each point on the leg bone along the normal direction of the preset osteotomy plane; The surface distance is used as a deformation variable, and the target pressure distribution is calculated based on Hooke's law; The target pressure distribution is determined based on the target pressure distribution and the preset area of ​​each sensing unit; The actual knee joint pressure data and the target pressure distribution are compared to determine whether the osteotomy has deviated.

4. The data acquisition system based on a planar knee joint pressure test pad according to claim 3, characterized in that, The step of comparing the actual knee joint pressure data with the target pressure distribution to determine whether the osteotomy has deviated includes: Extract the true pressure center location, true left-side pressure, true right-side pressure, and true left-right pressure difference from the actual knee joint pressure data; and Extract the target pressure center position, the pressure on the left side of the target, the pressure on the right side of the target, and the pressure difference between the left and right sides of the target pressure distribution. When the actual left pressure is less than the target left pressure and the actual right pressure is less than the target right pressure, or when the actual left pressure is greater than the target left pressure and the actual right pressure is greater than the target right pressure, the osteotomy position is determined to be offset. When the pressure offset between the actual left-right pressure difference and the target left-right pressure difference is greater than a preset threshold, the osteotomy angle is determined to be offset.

5. The data acquisition system based on a planar knee joint pressure test pad according to claim 4, characterized in that, The system also includes an intraoperative correction module. When determining the displacement of the osteotomy position, the intraoperative correction module is used to determine the thickness of the target pad based on the pressure displacement between the actual left and right pressure difference and the target left and right pressure difference, as well as a preset conversion coefficient. When determining the deviation of the osteotomy angle, the intraoperative correction module is used to calculate the compensation angle based on the center offset between the actual pressure center position and the target pressure center position.

6. The data acquisition system based on a planar knee joint pressure test pad according to claim 3, characterized in that, The offset determination module is also used for: The target pressure distribution was numerically verified using finite element analysis to generate an allowable error range. The step of comparing the actual knee joint pressure data with the target pressure distribution to determine whether the osteotomy has deviated includes: The actual knee joint pressure data is compared with the allowable error range to determine whether the osteotomy has deviated.

7. The data acquisition system based on a planar knee joint pressure test pad according to claim 6, characterized in that, The step of numerically verifying the target pressure distribution through finite element analysis and generating an allowable error range includes: Import the three-dimensional curved surface model, the geometric model of the planar knee joint pressure test pad, and the position information of the preset osteotomy plane into the finite element analysis software; Based on the finite element analysis software, corresponding material parameters are set for each key anatomical structure in the three-dimensional curved surface model and the geometric model of the planar knee joint pressure test pad; The target pressure distribution is converted into an equivalent normal force, and the equivalent normal force is applied to the three-dimensional surface model to obtain the simulated pressure distribution of the geometric model of the planar knee joint pressure test pad. Based on the target pressure distribution and the simulated pressure distribution, an allowable error range is generated.

8. The data acquisition system based on a planar knee joint pressure test pad according to claim 7, characterized in that, The step of generating an allowable error range based on the target pressure distribution and the simulated pressure distribution includes: Calculate the pressure difference between the target pressure distribution and the simulated pressure distribution in each sensing unit; The confidence interval of the pressure difference within a preset range is used as the upper limit of the node error, and the allowable error range is formed based on the envelope of all the node error upper limits.

9. A data acquisition method based on a planar knee joint pressure test pad, applied to the data acquisition system based on a planar knee joint pressure test pad as described in any one of claims 1-8, characterized in that, The method includes: Acquire initial knee joint pressure data collected by the pressure sensor array, as well as a three-dimensional surface model of the target knee joint; Determine the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array; Based on the virtual surface depth, preset compensation intensity, and preset sensitivity coefficient, the initial knee joint pressure data is compensated to obtain the actual knee joint pressure data; wherein... , For the first The actual knee joint pressure data after compensation by each sensing unit For the first Initial knee joint pressure data collected by each sensing unit For the first The virtual surface depth corresponding to the location of each sensing unit To preset the compensation strength, Preset sensitivity coefficient, preset compensation intensity The solution is obtained by substituting the actual knee joint pressure data measured with a curved pressure test pad and the initial knee joint pressure data measured with a flat knee joint pressure test pad back into the above formula through a preoperative calibration experiment. The optimal value, after compensation The result with the curved pressure test pad has the smallest error.

10. The data acquisition method based on a planar knee joint pressure test pad according to claim 9, characterized in that, Determining the virtual surface depth of the three-dimensional surface model in each sensing unit of the pressure sensor array includes: The three-dimensional curved surface model and the geometric model of the planar knee joint pressure test pad are registered in three-dimensional space to align the model coordinate system with the test pad coordinate system. Using each sensing unit in the pressure sensor array as a reference, a ray is projected onto the three-dimensional curved surface model along the normal direction of each sensing unit, and the intersection point of each ray with the surface of the three-dimensional curved surface model is determined. Calculate the vertical distance from each intersection point to the plane where the pressure sensor array is located, and use the vertical distance as the virtual surface depth of the corresponding sensing unit.

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