Knee joint motion analysis method and system

Abstract

The present invention relates to the field of motion analysis technology and provides a knee joint motion analysis method, comprising: S1: placing the knee joint in two X-ray devices and continuously taking X-ray images at different times; S2: marking two-dimensional anatomical feature points on the two X-ray images taken at the same time; S3: connecting the virtual X-ray light sources of the two X-ray devices with the two-dimensional anatomical feature points on the images, and using the intersection of the two connecting lines or the midpoint of the line segment with the closest distance between the two connecting lines as a three-dimensional anatomical feature point; S4: repeating step S3 to obtain a set of three-dimensional anatomical feature points of the knee joint; S5: establishing a local coordinate system including the femur, tibia, and patella based on the three-dimensional anatomical feature points in the set, and for any two coordinate systems, calculating the rotation matrix and displacement vector of one coordinate system relative to the other coordinate system to obtain the kinematic parameters of the patellofemoral and tibiofemoral joints. The spatial coordinate system of the bone is directly reconstructed from the feature points of the biplane images, thereby achieving rapid knee joint kinematic analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of motion analysis, and in particular to a knee joint motion analysis method and system. Background Art

[0002] Traditional biplane motion analysis relies on manual or automatic 2D-3D registration to reconstruct the spatial position of bones, or uses statistical shape models to directly generate corresponding 3D models from two 2D X-ray images to establish the spatial position of bones. This process is time-consuming and labor-intensive.

[0003] (1) Patent application CN112184782A performs image similarity matching on a virtual biplane X-ray sequence generated by projecting 3D volume data such as CT scans, and a real biplane X-ray sequence, and uses an optimization algorithm to automatically restore the 3D position of the bones. However, in this method, determining the initial position is crucial for automatic registration of the spatial position of the bones. With poor initial positions, the algorithm cannot register a large number of images to the appropriate position in space, so manual intervention is still required to obtain satisfactory results.

[0004] (2) Principal component analysis (PCA) is used to derive a statistical shape model (SSM) consisting of the average shape and its main variation patterns. The shape parameters are changed along the pattern to generate a new knee bone shape, and the surface models of the tibia and femur are aligned with the features in the biplane X-ray fluoroscopy image to achieve the acquisition of joint kinematics, reducing the time cost and possible radiation dose of three-dimensional model acquisition. However, in this method, the automatic modeling algorithm used has a high computational complexity. On a 2.26GHz processor with 24GB of memory, it takes 2 hours to calculate the knee kinematics based on SSM, including tracking and reconstructing the tibia and femur. In addition, most of the SSMs currently used are based on databases of healthy subjects. The degree of variation in subjects with skeletal deformities is large and generalization is difficult, making them unable to be applied to the estimation of knee kinematics in severe bone pathology. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a knee joint motion analysis method and system, which directly reconstructs the spatial coordinate system of the skeleton from the feature points of the biplane images to achieve rapid analysis of the knee joint kinematics.

[0006] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0007] A knee joint motion analysis method comprises the following steps:

[0008] S1: placing a knee joint to be analyzed in two non-overlapping X-ray devices, wherein the knee joint to be analyzed performs arbitrary translation and rotation movements within the fields of view of the two X-ray devices, and the X-ray devices continuously capture multiple sets of X-ray images at multiple different times;

[0009] S2: for the two X-ray images taken at the same moment, marking two-dimensional anatomical feature points for defining a three-dimensional anatomical coordinate system of the skeleton on the two X-ray images respectively;

[0010] S3: For the same 3D anatomical feature point, connect the virtual X-ray light sources simulated on the image processing device of the two X-ray devices with the 2D anatomical feature points corresponding to the 3D anatomical feature point on the two corresponding X-ray images, and use the intersection of the two connecting lines or the midpoint of the shortest distance between the two connecting lines as the 3D anatomical feature point;

[0011] S4: Repeat step S3 to obtain a set of three-dimensional anatomical feature points of a three-dimensional anatomical coordinate system defining the bones of the knee joint to be analyzed;

[0012] S5: Establish a local coordinate system including a femoral coordinate system, a tibial coordinate system, and a patellar coordinate system based on the three-dimensional anatomical feature points in the three-dimensional anatomical feature point set. For any two coordinate systems in the local coordinate system, calculate the rotation matrix and displacement vector of one coordinate system relative to the other coordinate system to obtain the kinematic parameters of the patellofemoral and tibiofemoral joints.

[0013] S6: For the two X-ray images at each moment, repeat steps S2-S5 to obtain continuous kinematic data of the knee joint to be analyzed.

[0014] Furthermore, in step S2, the method further includes: converting the two-dimensional anatomical feature points marked on the two X-ray images into the same coordinate system, specifically:

[0015] Taking any determined coordinate system including any actual physical space coordinate system of the X-ray device as the global coordinate system;

[0016] The two-dimensional anatomical feature points respectively marked on the two X-ray images are unified into the global coordinate system.

[0017] Furthermore, the actual physical space coordinate system of any one of the X-ray devices is used as the global coordinate system, and the two-dimensional anatomical feature points marked on the two X-ray images are unified into the global coordinate system, specifically:

[0018] The actual physical space coordinate systems of the two X-ray devices are C1 and C2 respectively, the conversion relationships between the image coordinate systems of the two X-ray devices and the actual physical space coordinate systems of the two X-ray devices are M1 and M2 respectively, and the relative position relationship of the two X-ray devices is R 12 ;

[0019] At the same time, the coordinates of the same three-dimensional anatomical feature point in the image coordinate systems of the two X-ray images are P1 = [x1, y1] and P2 = [x2, y2] respectively;

[0020] Convert P2 to the C1 coordinate system as follows:

[0021]

[0022] Convert P1 to C1 coordinate system, specifically:

[0023]

[0024] Furthermore, the steps of establishing the femoral coordinate system are:

[0025] The three-dimensional anatomical feature point set is recorded as P = [P G1 ,P G2 ,P G3 ,......,P GN ];

[0026] The origin of the femoral coordinate system is the line connecting the inner and outer malleolus of the femur, P G1 P G2 The midpoint o;

[0027] will be with the vector The parallel unit vector is used as the y-axis;

[0028] Connect the two points in the center of the femoral shaft to get the vector will be with the vector The parallel unit vector is translated to point O as z * axis;

[0029] Draw the y-axis and the z-axis * Axis cross product, x = z * ×y, get the x-axis;

[0030] Cross-product the x-axis and the y-axis, z = y × x, to obtain the z-axis.

[0031] Furthermore, the kinematic parameter calculation steps of the tibiofemoral joint are as follows:

[0032] The femur coordinate system is denoted as o-xyz, and the tibia coordinate system is denoted as O-XYZ;

[0033] The rotation matrix and displacement vector of the femoral coordinate system relative to the global coordinate system are R Femur =[x T y T z T ] and V Femur =[o x o y o z ] T ;

[0034] The rotation matrix and displacement vector of the tibia coordinate system relative to the global coordinate system are R Tibia =[X T Y T Z T ] and V Tibia =[O X O Y O Z ] T ;

[0035] The rotation matrix of the tibia coordinate system relative to the femur coordinate system is

[0036] The displacement vector of the tibia coordinate system relative to the femur coordinate system is Where T is the transpose of the matrix.

[0037] Furthermore, the tibia coordinate system is aligned to the femoral coordinate system in the order of first rotating around the Z axis of the tibia coordinate system, then rotating around the cross product vector direction of the Z axis of the tibia coordinate system and the y axis of the femoral coordinate system, and finally rotating around the y axis of the femoral coordinate system, by R T2F The three angles [a β γ] obtained by sequential rotation are respectively the internal and external rotation, internal and external valgus, and flexion and extension angles of the tibiofemoral joint.

[0038] A knee joint motion analysis system for executing the above-mentioned knee joint motion analysis method comprises:

[0039] An image capturing module is configured to place a knee joint to be analyzed in two non-overlapping X-ray devices, wherein the knee joint to be analyzed performs arbitrary translation and rotation movements within the fields of view of the two X-ray devices, and wherein the X-ray devices continuously capture multiple sets of X-ray images at multiple different times;

[0040] a two-dimensional feature point marking module, for marking two-dimensional anatomical feature points for defining a three-dimensional anatomical coordinate system of bones on the two X-ray images taken at the same moment;

[0041] a three-dimensional feature point acquisition module, configured to connect, for the same three-dimensional anatomical feature point, the virtual X-ray light sources simulated on the image processing device of the two X-ray devices and the two-dimensional anatomical feature points corresponding to the three-dimensional anatomical feature point on the two correspondingly taken X-ray images, and to use the intersection of the two connecting lines or the midpoint of the shortest distance between the two connecting lines as the three-dimensional anatomical feature point;

[0042] a feature point set acquisition module, configured to repeatedly execute the three-dimensional feature point acquisition module to acquire a three-dimensional anatomical feature point set of a defined bone three-dimensional anatomical coordinate system of the knee joint to be analyzed;

[0043] a kinematic parameter acquisition module, configured to establish a local coordinate system including a femoral coordinate system, a tibia coordinate system, and a patellar coordinate system based on the three-dimensional anatomical feature points in the three-dimensional anatomical feature point set, and to calculate, for any two coordinate systems in the local coordinate system, a rotation matrix and a displacement vector of one coordinate system relative to the other coordinate system, thereby acquiring kinematic parameters of the patellofemoral and tibiofemoral joints;

[0044] The continuous motion data acquisition module is used to acquire the continuous kinematic data of the knee joint to be analyzed based on the two X-ray images at each moment.

[0045] A computer device includes a memory and one or more processors, wherein the memory stores computer code, and when the computer code is executed by the one or more processors, the one or more processors execute the above method.

[0046] A computer-readable storage medium stores computer code. When the computer code is executed, the above method is performed.

[0047] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0048] (1) No additional software is required to reconstruct the 3D bone model, thus avoiding 3D model reconstruction errors caused by poor image quality;

[0049] (2) It does not rely on a large number of iterative algorithms for initial condition settings, has low computational complexity, and has low requirements for equipment;

[0050] (3) Rapidly obtain the three-dimensional position of the skeletal anatomical coordinate system to enable timely analysis of joint kinematics;

[0051] (4) Due to the direct selection of bone feature points, the generalization degree for subjects with skeletal deformities is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1This is an overall flow chart of a knee joint motion analysis method of the present invention;

[0053] Figure 2 This is a schematic diagram of the dual-plane three-dimensional anatomical feature point reconstruction of the present invention;

[0054] Figure 3 Schematic diagram of the three-dimensional anatomical coordinate system of the tibiofemoral joint of the present invention;

[0055] Figure 4 This is an overall structural diagram of a knee joint motion analysis system of the present invention. DETAILED DESCRIPTION

[0056] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0057] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a," "an," "said," and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0058] The knee joint motion analysis method and system of the present invention obtain knee joint kinematic parameters based on the three-dimensional reconstruction of the knee joint anatomical feature points and the corresponding anatomical coordinate system from biplane X-ray images. The three-dimensional coordinates of the feature points, including those of the femur, tibia, and patella, are reconstructed based on the spatially registered internal and external parameters of the biplane X-rays and directly identified anatomical feature points in the images. The corresponding skeletal anatomical coordinate system is then established to determine the absolute spatial position of each bone in the knee joint, as well as the relative six-degree-of-freedom rotational and displacement relationships.

[0059] The present invention reconstructs the three-dimensional spatial position of the knee joint feature points based on the two-dimensional coordinate system of the knee joint anatomical feature points on the biplane X-ray image, thereby establishing the anatomical coordinate system of the knee joint bones (including the femur, tibia, and patella), and obtains the relevant parameters of the joint kinematics according to the coordinate system transformation principle. This is specifically illustrated by the following specific examples:

[0060] First embodiment

[0061] like Figure 1As shown, this embodiment provides a knee joint motion analysis method, comprising the following steps:

[0062] S1: The knee joint to be analyzed is placed in two non-overlapping X-ray devices, and the knee joint to be analyzed performs movements including arbitrary translation and rotation within the field of view of the two X-ray devices. The X-ray devices continuously take multiple sets of X-ray images at multiple different times.

[0063] Specifically, for the knee joint motion analysis method of the present invention, two non-overlapping X-ray devices are required. The placement rule of the two X-ray devices only requires that the shooting range can cover the entire range of knee joint motion, and the shooting directions of the two X-ray devices do not overlap, that is, the shooting directions are not on the same straight line. Preferably, the two non-overlapping X-ray devices can be two X-ray devices with mutually perpendicular shooting directions, that is, a forward X-ray device and a lateral X-ray device, and the two X-ray devices with mutually perpendicular shooting directions simultaneously obtain X-ray images of the knee joint during motion at multiple different times.

[0064] The present invention includes, but is not limited to, X-ray equipment including C-arm X-ray machines, dynamic DR equipment, and ordinary static DR equipment. The present invention does not impose any restrictions on the specific type of X-ray equipment, as long as it can achieve the acquisition of X-ray images.

[0065] During the continuous X-ray imaging process, the knee joint can move in any direction, including translation and rotation, within the field of view of the two X-ray devices. Of course, it is also possible to image the knee joint in a stationary state.

[0066] S2: For the two X-ray images taken at the same moment, two-dimensional anatomical feature points for defining a three-dimensional anatomical coordinate system of bones are marked on the two X-ray images respectively.

[0067] Specifically, for two X-ray images taken at the same moment during the movement, two-dimensional anatomical feature points are marked on the X-ray images for the same three-dimensional anatomical feature point on the corresponding two X-ray images taken in different shooting directions. The marking method for the two-dimensional anatomical feature points can be obtained by automatically recognizing the anatomical feature points required to define the three-dimensional anatomical coordinate system of the skeleton (for example, for the distal femur, this includes the medial / lateral femoral condyle and femoral shaft; for the proximal tibia, this includes the medial / lateral tibial plateau center, tibial shaft, Gerdy's tubercle, etc.).

[0068] Furthermore, this step also includes: converting the two-dimensional anatomical feature points marked on the two X-ray images into the same coordinate system, specifically:

[0069] Any determined coordinate system, including the actual physical space coordinate system of any one of the X-ray devices, is used as a global coordinate system, and the two-dimensional anatomical feature points marked on the two X-ray images are unified into the global coordinate system. The global coordinate system can be any determined three-dimensional coordinate system.

[0070] For example, assuming that the actual physical space coordinate system of the lateral X-ray device is C1, and the actual physical space coordinate system of the forward X-ray device is C2, the coordinate system C1 is used as the global coordinate system, and the two-dimensional anatomical feature points marked on the two X-ray images are unified into the coordinate system C1. The specific calculation process is:

[0071] The conversion relationships between the coordinate systems of the respective image pixels acquired by the two X-ray devices and the actual physical space coordinate systems of the two X-ray devices are respectively M1 and M2, and the relative position relationship of the two X-ray devices is R 12 ;

[0072] For two corresponding X-ray images at the same moment, the coordinates of the same three-dimensional anatomical feature point in the image coordinate systems of the two X-ray images are P1=[x1, y1] and P2=[x2, y2] respectively;

[0073] The two-dimensional anatomical feature point P2 on the X-ray image taken by the forward X-ray device is converted to the C1 coordinate system, specifically:

[0074]

[0075] The two-dimensional anatomical feature point P1 on the X-ray image taken by the lateral X-ray device is converted to the C1 coordinate system, specifically:

[0076]

[0077] It should be noted that the above conversion to coordinate system C1 is only a specific example. The present invention can also use coordinate system C2 as the global coordinate system and convert all coordinates to coordinate system C2. Alternatively, any specific three-dimensional coordinate system can be used as the global coordinate system of the present invention.

[0078] S3: For the same three-dimensional anatomical feature point, connect the virtual X-ray light sources simulated on the image processing device of the two X-ray devices and the two-dimensional anatomical feature points corresponding to the three-dimensional anatomical feature point on the two corresponding X-ray images, and use the intersection of the two lines or the midpoint of the line segment with the shortest distance between the two lines as the three-dimensional anatomical feature point.

[0079] like Figure 2As shown, for the same 3D anatomical feature point, the 2D anatomical feature point converted to the same global coordinate system and the light source position of the X-ray image are connected. Ideally, the two straight lines will intersect at a point P. G Since the system may have errors, when the two straight lines do not intersect, the midpoint of the line segment representing the shortest distance between the two straight lines is taken as P G .

[0080] S4: Repeat step S3 to obtain the three-dimensional anatomical feature point set of the three-dimensional anatomical coordinate system of the knee joint to be analyzed. For the bones that need to establish the coordinate system, all the required three-dimensional anatomical feature point sets P = [P G1 ,P G2 ,P G3 ,......,P GN ].

[0081] S5: Establish a local coordinate system including a femoral coordinate system, a tibial coordinate system, and a patellar coordinate system based on the three-dimensional anatomical feature points in the three-dimensional anatomical feature point set. For any two coordinate systems in the local coordinate system, calculate the rotation matrix and displacement vector of one coordinate system relative to the other coordinate system to obtain the kinematic parameters of the patellofemoral and tibiofemoral joints.

[0082] Specifically, a local coordinate system of the skeleton is established based on the obtained three-dimensional anatomical feature points. In this embodiment, the local coordinate system follows the right-hand rule, and in actual operation, there is no such Figure 3 The skeleton model shown is only an example of feature points.

[0083] In this embodiment, if Figure 3 As shown, the process of establishing the femoral coordinate system is described as a specific example, specifically:

[0084] The origin of the femoral coordinate system is the line connecting the inner and outer malleolus of the femur, P G1 P G2 The midpoint o;

[0085] will be with the vector The parallel unit vector is used as the y-axis;

[0086] z * The axis is the femoral mechanical group. When the femoral head cannot be photographed due to imaging field of view, the femoral shaft center can be used instead. In this example, the vector is obtained by connecting the two points of the femoral shaft center. will be with the vector The parallel unit vector is translated to point O as z * axis;

[0087] Draw the y-axis and the z-axis * Axis cross product, x = z * ×y, get the x-axis;

[0088] At this time, the coordinate system formed by the three axes is not necessarily an orthogonal coordinate system, so the x-axis and the y-axis are cross-multiplied, z=y×x, and the result is used as the z-axis.

[0089] Similarly, the global coordinate system of the tibia and patella can be obtained. At this time, the origin and axis direction vectors of all local coordinate systems of the bones are expressed in the global coordinate system set uniformly in the previous article. By calculating the rotation matrix and displacement vector of one local coordinate system relative to another local coordinate system, the six-degree-of-freedom kinematic parameters of the patellofemoral and tibiofemoral joints can be obtained.

[0090] Taking the tibiofemoral joint as an example, the steps for calculating the kinematic parameters of the tibiofemoral joint are as follows:

[0091] The femur coordinate system is denoted as o-xyz, and the tibia coordinate system is denoted as O-XYZ;

[0092] The rotation matrix and displacement vector of the femoral coordinate system relative to the global coordinate system are R Femur =[x T y T z T ] and V Femur =[o x o y o z ] T , where T is the transpose of the matrix.

[0093] The rotation matrix and displacement vector of the tibia coordinate system relative to the global coordinate system are R Tibia =[X T Y T Z T ] and V Tibia =[O X O Y O Z ] T ;

[0094] The rotation matrix of the tibia coordinate system relative to the femur coordinate system is

[0095] The displacement vector of the tibia coordinate system relative to the femur coordinate system is

[0096] According to Grood & Suntay's definition of the six-degree-of-freedom motion of the tibia-femoral joint, the tibia coordinate system is aligned to the femoral coordinate system in the order of first rotating around the Z axis of the tibia coordinate system, then rotating around the cross product vector direction of the Z axis of the tibia coordinate system and the y axis of the femoral coordinate system, and finally rotating around the y axis of the femoral coordinate system. T2F The three angles [a β γ] obtained by sequential rotation are respectively the internal and external rotation, internal and external valgus, and flexion and extension angles of the tibiofemoral joint.

[0097] S6: For the two X-ray images at each moment, repeat steps S2-S5 to obtain continuous kinematic data of the knee joint to be analyzed.

[0098] Second embodiment

[0099] like Figure 4 As shown, this embodiment provides a knee joint motion analysis system for executing the knee joint motion analysis method as in the first embodiment, comprising:

[0100] An image capturing module 1 is configured to place a knee joint to be analyzed in two non-overlapping X-ray devices, wherein the knee joint to be analyzed is subjected to arbitrary translational and rotational motions within the fields of view of the two X-ray devices, and wherein the X-ray devices continuously capture multiple sets of X-ray images at multiple different times;

[0101] A two-dimensional feature point marking module 2 is used to mark two-dimensional anatomical feature points for defining a three-dimensional anatomical coordinate system of bones on the two X-ray images taken at the same time;

[0102] The three-dimensional feature point acquisition module 2 is configured to connect, for the same three-dimensional anatomical feature point, the virtual X-ray light sources simulated on the image processing device of the two X-ray devices and the two-dimensional anatomical feature points corresponding to the three-dimensional anatomical feature point on the two corresponding X-ray images, and use the intersection of the two connecting lines or the midpoint of the shortest distance between the two connecting lines as the three-dimensional anatomical feature point;

[0103] The feature point set acquisition module 4 is used to repeatedly execute the three-dimensional feature point acquisition module to acquire a three-dimensional anatomical feature point set of the three-dimensional anatomical coordinate system of the defined bones of the knee joint to be analyzed.

[0104] a kinematic parameter acquisition module 5, configured to establish a local coordinate system including a femoral coordinate system, a tibial coordinate system, and a patellar coordinate system based on the three-dimensional anatomical feature points in the three-dimensional anatomical feature point set, and to calculate, for any two coordinate systems in the local coordinate system, a rotation matrix and a displacement vector of one coordinate system relative to the other coordinate system, thereby acquiring kinematic parameters of the patellofemoral and tibiofemoral joints;

[0105] The continuous motion data acquisition module 6 is used to acquire the continuous kinematic data of the knee joint to be analyzed based on the two X-ray images at each moment.

[0106] A computer-readable storage medium stores computer code. When the computer code is executed, the above-described method is performed. A person skilled in the art will appreciate that all or part of the steps in the various methods of the above-described embodiments can be performed by a program instructing related hardware. The program can be stored in a computer-readable storage medium. The storage medium may include a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0107] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0108] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of the present invention. It should be pointed out that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A knee joint motion analysis method, characterized in that: The following steps are involved: S1: placing a knee joint to be analyzed in two non-overlapping X-ray devices, wherein the knee joint to be analyzed performs arbitrary translation and rotation movements within the fields of view of the two X-ray devices, and the X-ray devices continuously capture multiple sets of X-ray images at multiple different times; S2: for the two X-ray images taken at the same moment, marking two-dimensional anatomical feature points for defining a three-dimensional anatomical coordinate system of the skeleton on the two X-ray images respectively; S3: For the same 3D anatomical feature point, connect the virtual X-ray light sources simulated on the image processing device of the two X-ray devices with the 2D anatomical feature points corresponding to the 3D anatomical feature point on the two corresponding X-ray images, and use the intersection of the two connecting lines or the midpoint of the shortest distance between the two connecting lines as the 3D anatomical feature point; S4: Repeat step S3 to obtain a set of three-dimensional anatomical feature points of a three-dimensional anatomical coordinate system defining the bones of the knee joint to be analyzed; S5: Establish a local coordinate system including a femoral coordinate system, a tibial coordinate system, and a patellar coordinate system based on the three-dimensional anatomical feature points in the three-dimensional anatomical feature point set. For any two coordinate systems in the local coordinate system, calculate the rotation matrix and displacement vector of one coordinate system relative to the other coordinate system to obtain the kinematic parameters of the patellofemoral and tibiofemoral joints.

2. The knee joint motion analysis method according to claim 1, characterized in that: Also includes: S6: For the two X-ray images at each moment, repeat steps S2-S5 to obtain continuous kinematic data of the knee joint to be analyzed.

3. The knee joint motion analysis method according to claim 1, characterized in that: In step S2, the method further includes: converting the two-dimensional anatomical feature points marked on the two X-ray images into the same coordinate system, specifically: Taking any determined coordinate system including any actual physical space coordinate system of the X-ray device as the global coordinate system; The two-dimensional anatomical feature points respectively marked on the two X-ray images are unified into the global coordinate system.

4. The knee joint motion analysis method according to claim 3, characterized in that: The actual physical space coordinate system of any one of the X-ray devices is used as the global coordinate system, and the two-dimensional anatomical feature points marked on the two X-ray images are unified into the global coordinate system, specifically: The actual physical space coordinate systems of the two X-ray devices are C1 and C2 respectively, the conversion relationships between the image coordinate systems of the two X-ray devices and the actual physical space coordinate systems of the two X-ray devices are M1 and M2 respectively, and the relative position relationship of the two X-ray devices is R 12 ; At the same time, the coordinates of the same three-dimensional anatomical feature point in the image coordinate systems of the two X-ray images are P1 = [x1, y1] and P2 = [x2, y2] respectively; Convert P2 to the C1 coordinate system as follows: Convert P1 to C1 coordinate system, specifically:

5. The knee joint motion analysis method according to claim 1, characterized in that: The steps of establishing the femoral coordinate system are: The three-dimensional anatomical feature point set is recorded as P = [P G1 ,P G2 ,P G3 ,......,P GN ]; The origin of the femoral coordinate system is the line connecting the inner and outer malleolus of the femur, P G1 P G2 The midpoint o; will be with the vector The parallel unit vector is used as the y-axis; Connect the two points in the center of the femoral shaft to get the vector will be with the vector The parallel unit vector is translated to point O as z * axis; Draw the y-axis and the z-axis * Axis cross product, x = z * ×y, get the x-axis; Cross-product the x-axis and the y-axis, z = y × x, to obtain the z-axis.

6. The knee joint motion analysis method according to claim 3, characterized in that: The kinematic parameter calculation steps of the tibiofemoral joint are as follows: The femur coordinate system is denoted as o-xyz, and the tibia coordinate system is denoted as O-XYZ; The rotation matrix and displacement vector of the femoral coordinate system relative to the global coordinate system are R Femur =[x T y T z T ] and V Femur =[o x o y o z ] T ; The rotation matrix and displacement vector of the tibia coordinate system relative to the global coordinate system are R Tibia =[X T Y T Z T ] and V Tibia =[O X O Y O Z ] T ; The rotation matrix of the tibia coordinate system relative to the femur coordinate system is The displacement vector of the tibia coordinate system relative to the femur coordinate system is 7. The knee joint motion analysis method according to claim 6, characterized in that: Also includes: The tibia coordinate system is aligned to the femoral coordinate system in the order of first rotating around the Z axis of the tibia coordinate system, then rotating around the cross product vector direction of the Z axis of the tibia coordinate system and the y axis of the femoral coordinate system, and finally rotating around the y axis of the femoral coordinate system. T2F The three angles aβγ obtained by rotation in sequence are respectively the internal and external rotation, internal and external varus, and flexion and extension angles of the tibiofemoral joint.

8. A knee joint motion analysis system for executing the knee joint motion analysis method according to claims 1-7, characterized in that: include: An image capturing module is configured to place a knee joint to be analyzed in two non-overlapping X-ray devices, wherein the knee joint to be analyzed performs arbitrary translation and rotation movements within the fields of view of the two X-ray devices, and wherein the X-ray devices continuously capture multiple sets of X-ray images at multiple different times; a two-dimensional feature point marking module, for marking two-dimensional anatomical feature points for defining a three-dimensional anatomical coordinate system of bones on the two X-ray images taken at the same moment; a three-dimensional feature point acquisition module, configured to connect, for the same three-dimensional anatomical feature point, the virtual X-ray light sources simulated on the image processing device of the two X-ray devices and the two-dimensional anatomical feature points corresponding to the three-dimensional anatomical feature point on the two correspondingly taken X-ray images, and to use the intersection of the two connecting lines or the midpoint of the shortest distance between the two connecting lines as the three-dimensional anatomical feature point; a feature point set acquisition module, configured to repeatedly execute the three-dimensional feature point acquisition module to acquire a three-dimensional anatomical feature point set of a defined bone three-dimensional anatomical coordinate system of the knee joint to be analyzed; A kinematic parameter acquisition module is used to establish a local coordinate system including a femoral coordinate system, a tibial coordinate system, and a patellar coordinate system based on the three-dimensional anatomical feature points in the three-dimensional anatomical feature point set, and for any two coordinate systems in the local coordinate system, calculate the rotation matrix and displacement vector of one coordinate system relative to the other coordinate system to obtain the kinematic parameters of the patellofemoral and tibiofemoral joints.

9. The knee joint motion analysis system according to claim 8, characterized in that: Also includes: The continuous motion data acquisition module is used to acquire the continuous kinematic data of the knee joint to be analyzed based on the two X-ray images at each moment.

10. A computer device comprising a memory and one or more processors, wherein the memory stores computer code, and when the computer code is executed by the one or more processors, the one or more processors are caused to perform the method according to any one of claims 1 to 7.

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