Ligament isometric analysis method, device and system

Abstract

The present application provides a ligament isometric analysis method, device, and system, including: determining the center position of the femoral head based on the position set of the femoral positioning device during femoral rotation, and determining the center position of the ankle joint based on the medial and lateral malleolus positions; during knee flexion, converting the acquired femoral ligament insertion point position, intercondylar notch apex position, tibial ligament insertion point position, tibial plateau center position, femoral head center position, and ankle joint center position in the local coordinate system to a global coordinate system; determining the knee flexion angle based on the intercondylar notch apex position, tibial plateau center position, femoral head center position, and ankle joint center position in the global coordinate system; determining the ligament length based on the femoral ligament insertion point position and tibial ligament insertion point position in the global coordinate system to obtain the ligament length difference; and constructing a ligament isometric curve showing the ligament length difference as the knee flexion angle changes. The present application can improve the accuracy of determining the ligament insertion point position.

Description

Technical Field

[0001] The present application relates to the technical field of ligament analysis, and in particular to a method, device and system for ligament isometric analysis. Background Art

[0002] The anterior cruciate ligament (ACL) is primarily responsible for stabilizing knee movement and preventing the tibia from shifting forward relative to the femur. ACL injury can cause knee instability, impacting mobility and daily activities. ACL reconstruction is a common knee surgery used to repair ligament ruptures caused by sports injuries or other causes. The success of ACL reconstruction surgery depends on the location of the femoral and tibia bone tunnels, particularly the location of the ligament insertion.

[0003] In existing anterior cruciate ligament reconstruction surgeries, doctors use their own experience to determine the ligament attachment point position under arthroscopy, thereby determining the length of the graft. However, the manual determination of the ligament attachment point position is affected by many factors, and the ligament attachment point position is prone to inaccurate, resulting in the graft being too long or too short. A graft that is too long cannot provide sufficient tension, and a graft that is too short will cause collision with the intercondylar fossa, resulting in a low success rate of the surgery. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a ligament isometric analysis method, device and system, which can pre-evaluate the rationality of the ligament attachment point by simulating the ligament isometric curve of the ligament, improve the accuracy of determining the position of the ligament attachment point, and help improve the success rate of surgery.

[0005] In a first aspect, an embodiment of the present application provides a method for analyzing ligament isometric properties, the method comprising:

[0006] According to the original image data of the knee joint, the femoral ligament insertion point position, the intercondylar notch apex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau and the knee joint registration point position set are determined in the image coordinate system;

[0007] Determine the center position of the femoral head based on the acquired position set of the femoral positioning device during the femoral rotation process, and determine the center position of the ankle joint based on the acquired medial malleolus position and lateral malleolus position;

[0008] According to the registration relationship between the image coordinate system and the local coordinate system, the femoral ligament insertion point position, the intercondylar notch apex position, the tibial ligament insertion point position and the tibial plateau center position in the image coordinate system are converted from the image coordinate system to the local coordinate system; according to the mapping relationship between the global coordinate system and the local coordinate system, the femoral head center position and the ankle joint center position in the global coordinate system are converted from the global coordinate system to the local coordinate system; wherein the registration relationship is determined based on the position set of the knee joint positioning device and the knee joint registration point position set, and the tibial plateau center position is determined based on the medial edge point position and the lateral edge point position of the tibial plateau;

[0009] During the knee flexion movement, the femoral ligament insertion point position, intercondylar notch apex position, tibial ligament insertion point position, tibial plateau center position, femoral head center position and ankle joint center position obtained in the local coordinate system are converted from the local coordinate system to the global coordinate system;

[0010] The knee flexion angle during knee flexion is determined based on the intercondylar notch apex position, tibial plateau center position, femoral head center position, and ankle joint center position in the global coordinate system. The ligament length corresponding to different knee flexion angles is determined based on the femoral ligament insertion point position and tibial ligament insertion point position in the global coordinate system. The ligament length difference corresponding to different knee flexion angles is obtained by comparison with the reference ligament length.

[0011] A ligament isometric curve showing the difference in ligament length as a function of knee flexion angle was constructed to evaluate the rationality of the ligament insertion point based on the ligament isometric curve.

[0012] In an optional embodiment, the knee joint positioning device includes a femoral positioning device and a tibial positioning device, the femoral positioning device is fixed on the femur, and the tibial positioning device is fixed on the tibia;

[0013] The method of determining the femoral ligament insertion point position, the intercondylar notch vertex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, and the knee joint registration point position set in the image coordinate system based on the original image data of the knee joint includes:

[0014] According to the original image data of the knee joint, the femoral ligament insertion point position, the intercondylar notch vertex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, the femoral registration point position set, and the tibial registration point position set are determined in the image coordinate system;

[0015] The method converts the femoral ligament insertion point, intercondylar notch vertex position, tibial ligament insertion point and tibial plateau center position in the image coordinate system from the image coordinate system to the local coordinate system according to the registration relationship between the image coordinate system and the local coordinate system, and converts the femoral head center position and ankle joint center position in the global coordinate system from the global coordinate system to the local coordinate system according to the mapping relationship between the global coordinate system and the local coordinate system, including:

[0016] According to the femoral registration relationship between the image coordinate system and the femoral local coordinate system, the femoral ligament attachment point position and the intercondylar notch vertex position are converted from the image coordinate system to the femoral local coordinate system; according to the tibial registration relationship between the image coordinate system and the tibial local coordinate system, the tibial ligament attachment point position and the tibial plateau center position are converted from the image coordinate system to the tibial local coordinate system; according to the femoral mapping relationship between the global coordinate system and the femoral local coordinate system, the femoral head center position in the global coordinate system is converted from the global coordinate system to the femoral local coordinate system; according to the tibial mapping relationship between the global coordinate system and the tibial local coordinate system, the ankle joint center position in the global coordinate system is converted from the global coordinate system to the tibial local coordinate system; wherein, the femoral registration relationship is determined according to the position set of the femoral positioning device and the femoral registration point position set, and the tibial registration relationship is determined according to the position set of the tibial positioning device and the tibial registration point position set;

[0017] During knee flexion, the femoral ligament insertion point, intercondylar notch vertex, tibial ligament insertion point, tibial plateau center, femoral head center, and ankle joint center obtained in the local coordinate system are converted from the local coordinate system to the global coordinate system, including:

[0018] During knee flexion, the femoral ligament attachment point, intercondylar notch apex position and femoral head center position obtained in the femoral local coordinate system are converted from the femoral local coordinate system to the global coordinate system according to the femoral mapping relationship between the global coordinate system and the femoral local coordinate system. The tibial ligament attachment point, tibial plateau center position and ankle joint center position obtained in the tibial local coordinate system are converted from the tibial local coordinate system to the global coordinate system according to the tibial mapping relationship between the global coordinate system and the tibial local coordinate system.

[0019] In an optional embodiment, the femoral registration relationship and the tibial registration relationship are determined by the following steps:

[0020] Calculate the femoral transformation matrix and the tibial transformation matrix according to the posture returned by the femoral positioning device and the posture returned by the tibial positioning device respectively;

[0021] Determine a mapped femoral position set of the femoral positioning device in a femoral local coordinate system based on the femoral transformation matrix and the position set of the femoral positioning device; determine a mapped tibial position set of the tibial positioning device in a tibial local coordinate system based on the tibial transformation matrix and the position set of the tibial positioning device;

[0022] Constructing a femoral registration matrix based on the mapped femoral position set and the femoral registration point position set, so as to characterize the femoral registration relationship through the femoral registration matrix; constructing a tibial registration matrix based on the mapped tibial position set and the tibial registration point position set, so as to characterize the tibial registration relationship through the tibial registration matrix;

[0023] And, determining the femur mapping relationship and the tibia mapping relationship by the following steps:

[0024] Calculating a femoral transformation matrix according to the posture returned by the femoral positioning device, so as to represent the femoral mapping relationship through the femoral transformation matrix;

[0025] A tibial transformation matrix is ​​calculated according to the position and posture returned by the tibial positioning device, so as to represent the tibial mapping relationship through the tibial transformation matrix.

[0026] In an optional embodiment, determining the center position of the femoral head based on the acquired position set of the femoral positioning device during the femoral rotation process, and determining the center position of the ankle joint based on the acquired medial malleolus position and lateral malleolus position, includes:

[0027] Obtaining three-dimensional position coordinates of a femoral positioning device during femoral rotation to form a position set;

[0028] Determining the femoral head center position using a random sampling consensus algorithm based on the position set;

[0029] According to the obtained medial and lateral malleolus positions, the center position of the ankle joint is calculated using the midpoint formula.

[0030] In an optional embodiment, determining the femoral ligament insertion point position, the intercondylar notch apex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, the femoral registration point position set, and the tibial registration point position set in the image coordinate system based on the original image data of the knee joint includes:

[0031] Determine the femur segmentation model and the tibia segmentation model according to the original image data of the knee joint;

[0032] Obtaining the femoral ligament insertion point position and the intercondylar notch vertex position in the image coordinate system from the femoral segmentation model, and obtaining the tibial ligament insertion point position, the medial edge point position of the tibial plateau, and the lateral edge point position of the tibial plateau in the image coordinate system from the tibial segmentation model;

[0033] Feature points are selected on the surface of the femur segmentation model to form a femur registration point position set, and feature points are selected on the surface of the tibia segmentation model to form a tibia registration point position set.

[0034] In an optional embodiment, the method of determining the knee flexion angle during knee flexion according to the intercondylar notch apex position, tibial plateau center position, femoral head center position, and ankle joint center position in a global coordinate system, and determining the ligament lengths corresponding to different knee flexion angles according to the femoral ligament attachment point position and the tibial ligament attachment point position in the global coordinate system, and comparing the ligament lengths with the reference ligament lengths to obtain ligament length differences corresponding to different knee flexion angles, includes:

[0035] The femoral mechanical axis is determined according to the center position of the femoral head and the apex position of the intercondylar notch in the global coordinate system, and the tibial mechanical axis is determined according to the center position of the tibial plateau and the center position of the ankle joint in the global coordinate system;

[0036] Calculating the knee flexion angle during knee flexion according to the femoral mechanical axis and the tibial mechanical axis using a vector angle formula;

[0037] According to the femoral ligament insertion point position and tibial ligament insertion point position in the global coordinate system, the ligament length corresponding to different knee flexion angles was calculated using the three-dimensional distance formula;

[0038] The differences between the ligament lengths corresponding to different knee flexion angles and the reference ligament lengths corresponding to the specified knee flexion angles are calculated to obtain the ligament length differences corresponding to different knee flexion angles.

[0039] In an optional embodiment, constructing a ligament isometric curve showing the variation of ligament length difference with knee flexion angle, and evaluating the rationality of ligament insertion points based on the ligament isometric curve, includes:

[0040] Construct the ligament isometric curve showing the difference in ligament length as the knee flexion angle changes;

[0041] If the ligament length difference is within a preset length difference range, it is determined that the ligament attachment point is reasonable.

[0042] In a second aspect, an embodiment of the present application further provides a ligament isometric analysis device, the device comprising:

[0043] a data acquisition module, configured to determine, based on the original image data of the knee joint, the femoral ligament insertion point position, the intercondylar notch apex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, and the knee joint registration point position set in the image coordinate system;

[0044] a first processing module, configured to determine the center position of the femoral head according to the acquired position set of the femoral positioning device during the femoral rotation process, and determine the center position of the ankle joint according to the acquired medial malleolus position and lateral malleolus position;

[0045] a coordinate system alignment module for converting the femoral ligament insertion point, intercondylar notch apex, tibial ligament insertion point, and tibial plateau center position in the image coordinate system from the image coordinate system to the local coordinate system based on a registration relationship between the image coordinate system and the local coordinate system, and for converting the femoral head center position and ankle joint center position in the global coordinate system from the global coordinate system to the local coordinate system based on a mapping relationship between the global coordinate system and the local coordinate system; wherein the registration relationship is determined based on a position set of a knee joint positioning device and a position set of knee joint registration points, and the tibial plateau center position is determined based on a medial edge point position and a lateral edge point position of the tibial plateau;

[0046] A coordinate system conversion module is used to convert the acquired femoral ligament insertion point position, intercondylar notch apex position, tibial ligament insertion point position, tibial plateau center position, femoral head center position and ankle joint center position from the local coordinate system to the global coordinate system during knee flexion movement;

[0047] The second processing module is used to determine the knee flexion angle during the knee flexion movement based on the intercondylar notch apex position, the tibial plateau center position, the femoral head center position and the ankle joint center position in the global coordinate system, and determine the ligament length corresponding to different knee flexion angles based on the femoral ligament insertion point position and the tibial ligament insertion point position in the global coordinate system, so as to compare with the reference ligament length to obtain the ligament length difference corresponding to the different knee flexion angles;

[0048] The isometric analysis module is used to construct a ligament isometric curve showing the difference in ligament length as the knee flexion angle changes, so as to evaluate the rationality of the ligament insertion point based on the ligament isometric curve.

[0049] In the third aspect, an embodiment of the present application also provides a ligament isometric analysis system, which is applied to the ligament isometric analysis method as described above. The system includes: a visual device, a knee joint positioning device, a mobile positioning device and a processing device. The visual device is used to collect the position set of the knee joint positioning device and the position information of the mobile positioning device. The visual device is connected to the processing device.

[0050] In an optional embodiment, the knee joint positioning device includes a femoral positioning device and a tibial positioning device, the femoral positioning device is fixed on the femur, and the tibial positioning device is fixed on the tibia.

[0051] The ligament isometric analysis method provided in the embodiments of the present application has at least the following technical effects:

[0052] By first aligning the coordinate systems and then analyzing the position changes of the knee joint during flexion movement in the local coordinate system, the dynamic changes of the ligament attachment points during knee joint movement can be accurately captured. By simulating the dynamic changes of the knee joint during flexion movement, a ligament isometric curve is constructed to show the difference in ligament length as the flexion angle changes. The rationality of the ligament attachment points is evaluated through the ligament isometric curve, which improves the accuracy of determining the position of the ligament attachment points, thereby ensuring the rationality of the position of the ligament attachment points, and helping to improve the success rate of anterior cruciate ligament reconstruction surgery.

[0053] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1 A flowchart of a ligament isometric analysis method provided in an embodiment of the present application;

[0056] Figure 2 A schematic diagram of femoral rotation provided in an embodiment of the present application;

[0057] Figure 3 A schematic diagram of the knee flexion angle provided in an embodiment of the present application;

[0058] Figure 4 A schematic diagram of a ligament isometric curve provided in an embodiment of the present application;

[0059] Figure 5 A flowchart of another ligament isometric analysis method provided in an embodiment of the present application;

[0060] Figure 6 A schematic structural diagram of a ligament isometric analysis device provided in an embodiment of the present application;

[0061] Figure 7A schematic structural diagram of a ligament isometric analysis system provided in an embodiment of the present application;

[0062] Figure 8 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for which protection is claimed, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, each other embodiment obtained by those skilled in the art without making creative work falls within the scope of protection of the present application.

[0064] Research has found that the anterior cruciate ligament is mainly responsible for stabilizing knee joint movement and preventing the tibia from moving forward relative to the femur. Anterior cruciate ligament injury may cause the knee joint to lose stability, affecting athletic ability and daily activities. Anterior cruciate ligament reconstruction surgery is a common knee surgery, mainly used to repair ligament damage and rupture caused by sports injuries or other reasons. In anterior cruciate ligament reconstruction surgery, the position of the bone tunnels of the femur and tibia determines the key to the success or failure of the operation, especially the position of the ligament attachment point. In existing anterior cruciate ligament reconstruction surgeries, doctors use their own experience to determine the position of the ligament attachment point under arthroscopy, thereby determining the length of the graft. However, the manual method of determining the position of the ligament attachment point is affected by many factors, and it is easy for the ligament attachment point to be inaccurate, resulting in the graft being too long or too short. A graft that is too long cannot provide sufficient tension, and a graft that is too short will cause collision with the intercondylar notch, resulting in a low success rate for the operation.

[0065] Based on this, an embodiment of the present application provides a ligament isometric analysis method, which can pre-evaluate the rationality of the ligament attachment point by simulating the ligament isometric curve of the ligament, improve the accuracy of determining the position of the ligament attachment point, and help improve the success rate of surgery.

[0066] See also Figure 1 , Figure 1 This is a flow chart of a ligament isometric analysis method provided in an embodiment of the present application. Figure 1 As shown in , the method provided in the embodiment of the present application includes:

[0067] S101, determining, based on the original image data of the knee joint, the femoral ligament insertion point position, the intercondylar notch apex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, and the knee joint registration point position set in the image coordinate system;

[0068] S102, determining the center position of the femoral head based on the acquired position set of the femoral positioning device during the femoral rotation process, and determining the center position of the ankle joint based on the acquired medial and lateral malleolus positions;

[0069] S103. Based on the registration relationship between the image coordinate system and the local coordinate system, the femoral ligament insertion point, the intercondylar notch apex position, the tibial ligament insertion point position, and the tibial plateau center position in the image coordinate system are converted from the image coordinate system to the local coordinate system; and based on the mapping relationship between the global coordinate system and the local coordinate system, the femoral head center position and the ankle joint center position in the global coordinate system are converted from the global coordinate system to the local coordinate system; wherein the registration relationship is determined based on the position set of the knee joint positioning device and the knee joint registration point position set, and the tibial plateau center position is determined based on the medial edge point position and the lateral edge point position of the tibial plateau;

[0070] S104, during the knee flexion movement, converting the acquired femoral ligament insertion point position, intercondylar notch apex position, tibial ligament insertion point position, tibial plateau center position, femoral head center position, and ankle joint center position in the local coordinate system to the global coordinate system;

[0071] S105, determining the knee flexion angle during knee flexion based on the intercondylar notch apex position, the tibial plateau center position, the femoral head center position, and the ankle joint center position in the global coordinate system; determining the ligament lengths corresponding to different knee flexion angles based on the femoral ligament insertion point positions and the tibial ligament insertion point positions in the global coordinate system, and comparing the ligament lengths with the reference ligament lengths to obtain ligament length differences corresponding to different knee flexion angles;

[0072] S106. Construct a ligament isometric curve showing the difference in ligament length as a function of knee flexion angle, and evaluate the rationality of the ligament insertion point based on the ligament isometric curve.

[0073] In the above steps S101 to S106, the coordinate systems are first aligned, and then the position changes obtained by the knee flexion movement in the local coordinate system are analyzed. This can accurately capture the dynamic changes of the ligament attachment points during the knee joint movement. By simulating the dynamic changes of the knee joint during the knee flexion movement, a ligament isometric curve is constructed in which the ligament length difference changes with the knee flexion angle. By analyzing the ligament isometric curve, the rationality of the ligament attachment points is evaluated, and the accuracy of determining the position of the ligament attachment points is improved, thereby ensuring that the position of the ligament attachment points is reasonable, which helps to improve the success rate of anterior cruciate ligament reconstruction surgery.

[0074] The above steps are described in detail below through specific embodiments:

[0075] In step S101, based on the original image data of the knee joint, the femoral ligament attachment point position, the intercondylar notch vertex position, the tibial ligament attachment point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau and the knee joint registration point position set are determined in the image coordinate system. Here, the original image data of the knee joint can be image information of the knee joint obtained by CT scanning or other methods, which includes morphological and structural information of bones such as the femur and tibia; the femoral ligament insertion point is the attachment point of the anterior cruciate ligament on the femur, and its accurate position is crucial for anterior cruciate ligament reconstruction surgery; the intercondylar notch apex is the apex position of the femoral intercondylar notch, which is an important reference point in surgical planning; the tibial ligament insertion point is the attachment point of the anterior cruciate ligament on the tibia, and together with the femoral ligament insertion point, it determines the length and tension of the ligament; the medial edge point of the tibial plateau and the lateral edge point of the tibial plateau are specific position points on the edge of the tibial plateau, which are used to determine the center position of the tibial plateau; the knee joint registration point position set is a set of a series of feature points selected on the knee joint image, which is used for subsequent registration operations between the image and the real object. For example, the original image data of the knee joint can be obtained by a high-precision CT scanner, which can provide high-resolution images and clearly show the detailed structure of the bones. For example, before the actual surgical planning, the patient first undergoes a CT scan of the knee joint. The scanning equipment will image the knee joint from multiple angles, and ultimately obtain original image data containing a large number of feature points. In an optional embodiment, the knee joint registration point position set can select some obvious bony landmarks on the surface of the femur and tibia, such as protrusions, depressions, etc. For example, several representative protrusions on the surface of the femur are selected as registration points. These points are easy to identify on the CT image and the corresponding positions can be accurately found on the actual bones. In practical applications, taking the anterior cruciate ligament reconstruction surgery planning as an example, the original CT scan image data of the patient's knee joint is first obtained, and then professional medical image processing software can be used to mark the femoral ligament attachment point position, intercondylar notch apex position, tibial ligament attachment point position, tibial plateau medial edge point position and tibial plateau lateral edge point position on the image, and at the same time select a suitable set of knee joint registration point positions to provide basic data for subsequent analysis and surgical planning. Through the above processing, the femoral ligament attachment point position, intercondylar notch apex position, tibial ligament attachment point position, tibial plateau medial edge point position, tibial plateau lateral edge point position and knee joint registration point position set can be obtained in the image coordinate system.

[0076] In step S102, the center position of the femoral head is determined based on the position set of the femoral positioning device during the femoral rotation, and the center position of the ankle joint is determined based on the medial malleolus position and lateral malleolus position. In this step, the femoral positioning device is a device fixed on the femur and used to assist in determining the femoral position information. It will generate a series of position change data during the femoral rotation process. Figure 2As shown, the femoral head center position is the center point of femoral rotation. The position set of the femoral positioning device during femoral rotation refers to the set of position information of the femoral positioning device at different times when the femur rotates around the femoral head center. The medial malleolus position and lateral malleolus position are the positions of the ankle protrusions formed on the medial and lateral sides of the lower ends of the tibia and fibula, respectively, and are used to determine the center position of the ankle joint. In an optional embodiment, the femoral positioning device can be a device with multiple reflective marking points, and the positions of these marking points in space can be tracked in real time using equipment such as an optical locator. For example, in a femoral rotation experiment, the femoral positioning device is fixed to the femur. As the femur rotates, the optical locator continuously collects the position information of the marking points, thereby obtaining the position set of the femoral positioning device during femoral rotation. Furthermore, the femoral head center position can be determined using a random sample consensus algorithm (RANSAC). That is, multiple points are randomly selected from the position set of the femoral positioning device and the femoral head center position is determined by spherical fitting. Assuming that these points are on a sphere with the center of the femoral head as the center, a more accurate position of the center of the femoral head is finally obtained through continuous iterative calculation.

[0077] Specifically, the three-dimensional position coordinates of the femoral positioning device during femoral rotation are obtained to form a position set. That is, during the simulated knee flexion movement, the visual device continuously tracks the position of the markers on the femoral positioning device, and the three-dimensional coordinates (x, y, z) of the markers recorded at each moment are added to the position set. The visual device can be an optical locator, and based on the position set, a random sampling consensus algorithm is used to determine the center position of the femoral head.

[0078] For example, the femur is rotated slowly and steadily with the center of the femoral head as the center, and the position set of the femoral positioning device is collected in the global coordinate system. , according to the random sampling consistency algorithm, select four non-coplanar points in G , from the standard equation of a sphere (where (a, b, c) is the center of the sphere and r is the radius) ,make , we get the linear equations , solve this system of equations to get (a, b, c, d), and then according to , get the radius r of the circle, and for all data points, calculate the distance error to the sphere: ,like < preset threshold, it is marked as an inlier. Iterate the above steps, if the proportion of inliers exceeds the set threshold (such as 95%) or reaches the maximum number of iterations , (where p is the expected success probability, w is the proportion of internal points, and k is the minimum number of samples) the iteration can be terminated, and the center of the circle (a, b, c) is finally obtained as the center position of the femoral head, which is recorded as .

[0079] The above method can effectively eliminate the interference of external points and accurately find the internal points that conform to the spherical model (i.e., conform to the femoral rotation characteristics) from noisy data, thereby more accurately determining the center position of the femoral head.

[0080] In an optional embodiment, the medial and lateral malleolus positions can be acquired using a mobile positioning device (e.g., a probe with a sensor). For example, in the preoperative preparation phase, the medial and lateral malleolus positions are measured using a mobile positioning device, and then the ankle joint center position is calculated using the midpoint formula. For example, the medial malleolus position is acquired using the mobile positioning device in a global coordinate system. , lateral ankle position , according to the formula Get the ankle center position , where t is a constant value. For example, t can be set to 0.46.

[0081] In actual applications, during preoperative planning for anterior cruciate ligament reconstruction surgery, the femoral positioning device is fixed to the patient's femur to simulate the rotation process of the femur during knee joint movement. The position set of the femoral positioning device is collected using an optical positioner, and then the center position of the femoral head is calculated using a random sampling consistency algorithm. At the same time, a mobile positioning device is used to measure the medial and lateral malleolus positions, and then the midpoint formula is used to determine the center position of the ankle joint, providing key position information for subsequent knee joint motion analysis.

[0082] In step S103, based on the registration relationship between the image coordinate system and the local coordinate system, the femoral ligament insertion point position, the intercondylar notch vertex position, the tibial ligament insertion point position and the tibial plateau center position in the image coordinate system are converted from the image coordinate system to the local coordinate system, and based on the mapping relationship between the global coordinate system and the local coordinate system, the femoral head center position and the ankle joint center position in the global coordinate system are converted from the global coordinate system to the local coordinate system; wherein, the registration relationship is determined based on the position set of the knee joint positioning device and the knee joint registration point position set, and the tibial plateau center position is determined based on the tibial plateau medial edge point position and the tibial plateau lateral edge point position. Here, the image coordinate system is a coordinate system established based on the acquired original image of the knee joint, which is used to describe the position of each point in the image. The global coordinate system is a unified coordinate system used to describe the position and motion state of the entire knee joint in space. The embodiment of the present application is established based on the visual device, that is, the global coordinate system can also be defined as the visual device coordinate system, that is, the world coordinate system. The local coordinate system is a relative coordinate system established to facilitate accurate analysis of the various structural components of the knee joint. Specifically, it includes the femoral local coordinate system established relative to the femur and the tibial local coordinate system established relative to the tibia. The registration relationship refers to the transformation relationship between the image coordinate system and the local coordinate system. This relationship allows the positional information in the image to be accurately converted to the actual knee joint local coordinate system. This can be calculated using a specific algorithm, such as a registration algorithm. The mapping relationship refers to the transformation relationship between the global coordinate system and the local coordinate system, which is used to unify positional information in different coordinate systems.

[0083] Exemplarily, the registration relationship can be calculated using an iterative closest point (ICP) algorithm. For example, based on the position set of the knee joint positioning device and the position set of the knee joint registration points, the ICP algorithm is used to iteratively calculate and find the optimal rotation and translation parameters, thereby determining the registration relationship between the image coordinate system and the local coordinate system.

[0084] Optionally, the tibial plateau center position is determined based on the medial edge point position of the tibial plateau and the lateral edge point position of the tibial plateau, specifically, obtaining the medial edge point position of the tibial plateau and the lateral edge of the tibial plateau , by calculating Get the tibial plateau center position .

[0085] For example, a knee joint positioning device can be fixed to the knee joint, and the vision device can collect the position set of the knee joint positioning device and perform registration in combination with the position set of the knee joint registration points. Specifically, the knee joint positioning device can include a femoral positioning device and a tibial positioning device, which are fixed to the femur and tibia, respectively, to provide spatial position information of the femur and tibia.

[0086] Furthermore, when planning anterior cruciate ligament reconstruction surgery, the image coordinate system, global coordinate system and local coordinate system are first determined. Then, based on the position set of the knee joint positioning device and the previously determined knee joint registration point position set, the registration algorithm is used to calculate the registration relationship between the image coordinate system and the local coordinate system. Then, key positions such as the femoral ligament insertion point position and the intercondylar notch apex position are converted from the image coordinate system to the local coordinate system. According to the mapping relationship between the global coordinate system and the local coordinate system, the femoral head center position and ankle joint center position in the global coordinate system are converted from the global coordinate system to the local coordinate system to prevent the knee joint position or the visual device from moving during the acquisition and registration process.

[0087] In step S104, during the knee flexion movement, the femoral ligament attachment point position, intercondylar notch apex position, tibial ligament attachment point position, tibial plateau center position, femoral head center position and ankle joint center position obtained in the local coordinate system are converted from the local coordinate system to the global coordinate system.

[0088] Among them, during the knee flexion movement, the coordinates of each key position point of the knee joint in the local coordinate system are collected in real time, and the mapping relationship between the global coordinate system and the local coordinate system is used to convert these coordinates into the global coordinate system, so as to analyze the movement state of the knee joint and the relationship between each position point from a holistic perspective.

[0089] In an optional embodiment, a visual device mounted on the operating table monitors the positional changes of the knee positioning device in real time during knee flexion, thereby obtaining the latest coordinates of each key position point in the local coordinate system. For example, before surgery, when the surgeon manually flexes and extends the patient's knee, the visual device continuously collects positional information of the femoral positioning device and the tibial positioning device, thereby determining the coordinates of each position point in the local femoral coordinate system and the local tibial coordinate system.

[0090] For example, when converting coordinates from a local coordinate system to a global coordinate system, the coordinates can be transformed using a transformation matrix based on the previously determined mapping relationship between the global coordinate system and the local coordinate system. For example, the coordinates of the femoral ligament insertion point in the femoral local coordinate system can be multiplied by the corresponding femoral transformation matrix to obtain their coordinates in the global coordinate system.

[0091] In step S105, the flexion angle of the knee joint during the flexion movement is determined based on the intercondylar notch apex position, tibial plateau center position, femoral head center position and ankle joint center position in the global coordinate system, and the ligament length corresponding to different flexion angles is determined based on the femoral ligament attachment point position and tibial ligament attachment point position in the global coordinate system, and the ligament length corresponding to different flexion angles is compared with the reference ligament length to obtain the ligament length difference corresponding to different flexion angles. Here, the flexion angle refers to the change in the angle between the femur and tibia when the knee joint performs flexion movement. The ligament length refers to the distance between the femoral ligament attachment point and the tibial ligament attachment point at different flexion angles. The reference ligament length is a pre-set standard length value, and the ligament length at a specific flexion angle (such as 90 degrees) can usually be selected as a reference. In an optional embodiment, the flexion angle can be determined based on the vector angle formula. Specifically: the femoral mechanical axis is determined based on the center position of the femoral head and the apex position of the intercondylar notch in the global coordinate system, and the tibial mechanical axis is determined based on the center position of the tibial plateau and the center position of the ankle joint in the global coordinate system; based on the femoral mechanical axis and the tibial mechanical axis, the vector angle formula is used to calculate the knee flexion angle during knee flexion movement.

[0092] That is to say, the vector formed by the center position of the femoral head and the apex position of the intercondylar notch is used as the direction vector of the femoral mechanical axis, and the vector formed by the center position of the tibial plateau and the center position of the ankle joint is used as the direction vector of the tibial mechanical axis. The knee flexion angle is determined by calculating the angle between these two vectors.

[0093] For example, Figure 3 As shown, the center position of the femoral head in the global coordinate system is defined , the position of the apex of the intercondylar notch in the global coordinate system , then the femoral mechanical axis , define the midpoint of the tibial plateau in the global coordinate system as , the midpoint position of the ankle joint in the global coordinate system , then the tibial mechanical axis , according to the vector angle formula , calculate the knee flexion angle In an optional embodiment, the ligament length differences corresponding to different knee flexion angles can be determined using a three-dimensional distance formula. Specifically: based on the femoral ligament attachment point position and the tibial ligament attachment point position in the global coordinate system, the ligament lengths corresponding to different knee flexion angles are calculated using a three-dimensional distance formula; the differences between the ligament lengths corresponding to different knee flexion angles and the reference ligament lengths corresponding to the specified knee flexion angles are calculated to obtain the ligament length differences corresponding to different knee flexion angles.

[0094] For example, the femoral ligament insertion point position in the global coordinate system is defined as , the insertion point of the tibial ligament in the global coordinate system is , ligament length , assuming the ligament length when the angle is 90 degrees is is the reference ligament length, the ligament length difference .

[0095] Specifically, given the three-dimensional coordinates of the femoral and tibial ligament insertions at different knee flexion angles in a global coordinate system, the distance between the two points is calculated using a three-dimensional distance formula to obtain the ligament length at each flexion angle. This distance is then subtracted from the reference ligament length to obtain the ligament length difference corresponding to each flexion angle. In step S106, a ligament isometric curve is constructed to show the ligament length difference as a function of flexion angle, and the rationality of the ligament insertions is evaluated based on the ligament isometric curve. The ligament isometric curve is constructed with flexion angle as the horizontal axis and ligament length difference as the vertical axis, visually displaying the changes in ligament length at different knee flexion angles. Assessing the rationality of the ligament insertions involves analyzing the ligament isometric curve to determine whether the currently set femoral and tibial ligament insertions are reasonable and whether they ensure ligament isometric stability during knee joint motion.

[0096] For example, control the knee joint to flex between 30 degrees and 120 degrees, and collect the knee flexion angle and ligament length data. The reference ligament length when the knee flexion angle is 90 degrees is recorded as , generate the difference set of knee flexion angle and ligament length , draw the ligament isometric curve.

[0097] In an optional embodiment, a preset length difference range can be set to evaluate the rationality of the ligament attachment point. Specifically, step S105 specifically includes: constructing a ligament isometric curve showing the change of ligament length difference with knee flexion angle; if the ligament length difference is within the preset length difference range, then the ligament attachment point is determined to be reasonable. For example, during the knee flexion movement, With the transformation data set of knee flexion angle θ, the horizontal axis is the knee flexion angle θ. Length difference As the vertical axis, draw the ligament isometric curve, such as Figure 4 As shown, if the ligament length difference is between (-2mm, 2mm), it is considered that the ligament is of good isometry and the ligament attachment point is in a reasonable position, and the next surgery can be performed; if it exceeds this range, the doctor needs to adjust the position of the ligament attachment point based on experience or further analysis.

[0098] Furthermore, after obtaining ligament length difference data at different knee flexion angles, specialized software can be used to construct a ligament isometric curve. Doctors or researchers can assess the rationality of the ligament insertion by observing the curve shape and analyzing whether the ligament length difference is within the preset length difference range. If the ligament insertion is unreasonable, the position of the ligament insertion in the surgical plan is readjusted to ensure that the ligaments during surgery are biomechanically isometric, thereby improving the success rate of anterior cruciate ligament reconstruction surgery.

[0099] See also Figure 5 , Figure 5 This is a flow chart of another ligament isometric analysis method provided in an embodiment of the present application, such as Figure 5 As shown, the method provided in the embodiment of the present application includes:

[0100] S501. Determine, based on the original image data of the knee joint, the femoral ligament insertion point position, the intercondylar notch vertex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, the femoral registration point position set, and the tibial registration point position set in the image coordinate system;

[0101] S502, determining the center position of the femoral head based on the acquired position set of the femoral positioning device during the femoral rotation process, and determining the center position of the ankle joint based on the acquired medial malleolus position and lateral malleolus position;

[0102] S503, according to the femoral registration relationship between the image coordinate system and the femoral local coordinate system, converting the femoral ligament insertion point position and the intercondylar notch vertex position from the image coordinate system to the femoral local coordinate system; according to the tibial registration relationship between the image coordinate system and the tibial local coordinate system, converting the tibial ligament insertion point position and the tibial plateau center position from the image coordinate system to the tibial local coordinate system; according to the femoral mapping relationship between the global coordinate system and the femoral local coordinate system, converting the femoral head center position in the global coordinate system from the global coordinate system to the femoral local coordinate system; according to the tibial mapping relationship between the global coordinate system and the tibial local coordinate system, converting the ankle joint center position in the global coordinate system from the global coordinate system to the tibial local coordinate system; wherein the femoral registration relationship is determined based on the position set of the femoral positioning device and the femoral registration point position set, and the tibial registration relationship is determined based on the position set of the tibial positioning device and the tibial registration point position set;

[0103] S504. During knee flexion, the femoral ligament insertion point, intercondylar notch apex position, and femoral head center position acquired in the femoral local coordinate system are converted from the femoral local coordinate system to the global coordinate system based on the femoral mapping relationship between the global coordinate system and the femoral local coordinate system. Furthermore, the tibial ligament insertion point, tibial plateau center position, and ankle joint center position acquired in the tibial local coordinate system are converted from the tibial local coordinate system to the global coordinate system based on the tibial mapping relationship between the global coordinate system and the tibial local coordinate system.

[0104] S505, determining the knee flexion angle during the knee flexion movement based on the intercondylar notch apex position, the tibial plateau center position, the femoral head center position, and the ankle joint center position in the global coordinate system; determining the ligament lengths corresponding to different knee flexion angles based on the femoral ligament insertion point positions and the tibial ligament insertion point positions in the global coordinate system, and comparing the ligament lengths with the reference ligament lengths to obtain ligament length differences corresponding to different knee flexion angles;

[0105] S506. Construct a ligament isometric curve showing how the ligament length difference changes with the knee flexion angle, and evaluate the rationality of the ligament insertion point based on the ligament isometric curve.

[0106] Among them, the above steps S502, S505 and S506 can refer to steps S102, S105 and S106, and can achieve the same technical effects, which will not be repeated here.

[0107] In step S501, the original image data, typically a CT scan of the knee joint, is used to separate the 3D models of the femur and tibia from the CT data using image processing algorithms (such as threshold segmentation, region growing, and level set algorithms). The anatomical landmarks required for surgical planning are precisely located within the segmented models, all of which are in the global coordinate system.

[0108] Here, step S501 specifically includes: determining the femoral segmentation model and the tibial segmentation model based on the original image data of the knee joint; obtaining the femoral ligament attachment point position and the intercondylar notch vertex position in the image coordinate system from the femoral segmentation model, and obtaining the tibial ligament attachment point position, the medial edge point position of the tibial plateau and the lateral edge point position of the tibial plateau in the image coordinate system from the tibial segmentation model; selecting feature points on the surface of the femoral segmentation model to form a femoral alignment point position set, and selecting feature points on the surface of the tibial segmentation model to form a tibial alignment point position set.

[0109] The femoral ligament insertion point and intercondylar notch vertex position in the image coordinate system can be directly obtained from the femoral segmentation model. The tibial ligament insertion point, medial edge of the tibial plateau, and lateral edge of the tibial plateau can be directly obtained from the tibial segmentation model. Several feature points (such as protrusions, depressions, or areas with significant curvature changes on the bone surface) are manually or automatically selected from the surfaces of the femoral and tibial segmentation models to form a set of femoral and tibial registration point positions, respectively.

[0110] In step S503, according to the femoral registration relationship between the image coordinate system and the local femoral coordinate system, the femoral ligament attachment point position and the intercondylar notch vertex position are converted from the image coordinate system to the local femoral coordinate system; according to the tibial registration relationship between the image coordinate system and the local tibial coordinate system, the tibial ligament attachment point position and the tibial plateau center position are converted from the image coordinate system to the local tibial coordinate system; according to the femoral mapping relationship between the global coordinate system and the local femoral coordinate system, the femoral head center position in the global coordinate system is converted from the global coordinate system to the local femoral coordinate system; according to the tibial mapping relationship between the global coordinate system and the local tibial coordinate system, the ankle joint center position in the global coordinate system is converted from the global coordinate system to the local tibial coordinate system; wherein, the femoral registration relationship is determined based on the position set of the femoral positioning device and the femoral registration point position set, and the tibial registration relationship is determined based on the position set of the tibial positioning device and the tibial registration point position set.

[0111] Here, the femoral local coordinate system refers to the coordinate system fixed to the femur, the origin can be the center of the femoral head, and the coordinate axis direction can be aligned with the mechanical axis of the femur; the tibial local coordinate system refers to the coordinate system fixed to the tibia, the origin can be the center of the ankle joint, and the coordinate axis can be aligned with the mechanical axis of the tibia.

[0112] Specifically, the positions of the femoral ligament attachment point and the intercondylar notch apex in the femoral local coordinate system are fixed, and the positions of the tibial ligament attachment point and the tibial plateau center in the tibial local coordinate system are fixed. Furthermore, in order to prevent the knee joint position or the visual device from moving during the acquisition and alignment process, the femoral ligament attachment point and the intercondylar notch apex are converted from the image coordinate system to the femoral local coordinate system, and the tibial ligament attachment point and the tibial plateau center are converted from the image coordinate system to the tibial local coordinate system, so that these feature points are not affected by individual body position changes.

[0113] In an optional embodiment, the femoral transformation matrix and the tibial transformation matrix are calculated respectively based on the posture returned by the femoral positioning device and the posture returned by the tibial positioning device; the femoral registration matrix is ​​constructed based on the position set of the femoral positioning device, the femoral transformation matrix and the femoral registration point position set; and the tibial registration matrix is ​​constructed based on the position set of the tibial positioning device, the tibial transformation matrix and the tibial registration point position set.

[0114] Specifically, the femur registration relationship and the tibia registration relationship are determined by the following steps:

[0115] According to the posture returned by the femoral positioning device and the posture returned by the tibial positioning device, a femoral transformation matrix and a tibial transformation matrix are calculated respectively; according to the femoral transformation matrix and the position set of the femoral positioning device, a mapped femoral position set of the femoral positioning device in the femoral local coordinate system is determined; according to the tibial transformation matrix and the position set of the tibial positioning device, a mapped tibial position set of the tibial positioning device in the tibial local coordinate system is determined; according to the mapped femoral position set and the femoral registration point position set, a femoral registration matrix is ​​constructed to characterize the femoral registration relationship through the femoral registration matrix; according to the mapped tibial position set and the tibial registration point position set, a tibial registration matrix is ​​constructed to characterize the tibial registration relationship through the tibial registration matrix;

[0116] And, determine the femur mapping relationship and tibia mapping relationship through the following steps:

[0117] The femoral transformation matrix is ​​calculated according to the posture returned by the femoral positioning device to represent the femoral mapping relationship through the femoral transformation matrix; the tibial transformation matrix is ​​calculated according to the posture returned by the tibial positioning device to represent the tibial mapping relationship through the tibial transformation matrix.

[0118] In other words, determining the femoral registration relationship, tibial registration relationship, femoral mapping relationship, and tibial mapping relationship primarily relies on the pose and position set data returned by the positioning devices (femoral positioning device and tibial positioning device). The femoral transformation matrix is ​​calculated using the pose returned by the femoral positioning device. Combined with its position set, the mapped femoral position set in the femoral local coordinate system is determined. This mapped femoral position set, combined with the femoral registration point position set, constructs the femoral registration matrix, representing the femoral registration relationship. Similarly, the same operation is performed for the tibial positioning device to determine the tibial registration relationship. When determining the mapping relationship, the transformation matrices are calculated directly based on the poses returned by the femoral and tibial positioning devices, respectively, and these matrices are used to represent their respective mapping relationships.

[0119] The determination of the above-mentioned registration and mapping relationships can accurately convert the image coordinate system and the local coordinate system, and the global coordinate system and the local coordinate system, which helps to achieve accurate analysis of ligament isometrics.

[0120] For example, the femoral registration point position set , tibia registration point location set Positioning device (femoral positioning device, tibial positioning device) returns to the position , according to the unit quaternion, the corresponding rotation matrix is ​​obtained

[0121] , the translation vector The transformation matrix is ​​obtained from the rotation matrix and the translation vector , and then, according to the posture returned by the femoral positioning device Determine the femoral transformation matrix Similarly, according to the posture returned by the tibial positioning device The tibial transformation matrix can be determined In the global coordinate system, the position set of the femoral positioning device is collected and the position set of the tibial positioning device According to the femoral mapping relationship between the global coordinate system and the femoral local coordinate system, the position set of the femoral positioning device is converted to the femoral local coordinate system to obtain the mapped femoral position set According to the tibia mapping relationship between the global coordinate system and the tibia local coordinate system, the position set of the tibia positioning device is converted to the tibia local coordinate system to obtain the mapped tibia position set ,according to and , the femoral registration matrix can be obtained using the registration algorithm ,according to and , the tibia registration matrix can be obtained using the registration algorithm .

[0122] For the femoral ligament insertion point position and the intercondylar notch vertex position in the image coordinate system, the femoral ligament insertion point position and the intercondylar notch vertex position are converted to the femoral local coordinate system through the femoral registration matrix. For the tibial ligament insertion point position and the tibial plateau center position in the image coordinate system, the tibial ligament insertion point position and the tibial plateau center position are converted to the tibial local coordinate system through the tibial registration matrix. For the femoral head center position in the global coordinate system, the femoral head center position is converted to the femoral local coordinate system according to the femoral mapping relationship between the global coordinate system and the femoral local coordinate system. For the ankle joint center position in the global coordinate system, the ankle joint center position is converted to the tibial local coordinate system according to the tibial mapping relationship between the global coordinate system and the tibial local coordinate system.

[0123] Here, the image coordinate system is transformed into the local coordinate system (femur local coordinate system and tibia local coordinate system), according to the coordinate transformation formula Calculate, where represents the position coordinates in the local coordinate system, Represents the position coordinates in the image coordinate system, Represents the registration matrix, including the femur registration matrix and tibia registration matrix . Convert from the global coordinate system to the local coordinate system (femur local coordinate system and tibia local coordinate system), according to the coordinate conversion formula Calculate, where Represents the position coordinates in the global coordinate system, Represents the transformation matrix, including the femur transformation matrix and the tibia transformation matrix .

[0124] From the local coordinate system (femur local coordinate system and tibia local coordinate system) to the global coordinate system, according to the coordinate transformation formula Calculate, where Represents the inverse transformation of the transformation matrix, including the inverse transformation of the femoral transformation matrix and the inverse transformation of the tibial transformation matrix .

[0125] During preoperative planning, the image coordinates of the femoral ligament insertion and intercondylar notch apex were converted to the local femoral coordinate system using the femoral registration matrix. The image coordinates of the tibial ligament insertion and tibial plateau center were converted to the local tibial coordinate system using the tibial registration matrix. The global coordinates of the femoral head center were converted to the local femoral coordinate system using the femoral transformation matrix, and the global coordinates of the ankle joint center were converted to the local tibial coordinate system using the tibial transformation matrix.

[0126] The embodiments of the present application achieve accurate mapping of anatomical structures in different coordinate systems through registration matrices and transformation matrices, thereby avoiding positioning errors caused by differences in coordinate systems.

[0127] In step S504, during the knee flexion movement, the femoral ligament attachment point position, intercondylar notch apex position and femoral head center position obtained in the femoral local coordinate system are converted from the femoral local coordinate system to the global coordinate system according to the femoral mapping relationship between the global coordinate system and the femoral local coordinate system. The tibial ligament attachment point position, tibial plateau center position and ankle joint center position obtained in the tibial local coordinate system are converted from the tibial local coordinate system to the global coordinate system according to the tibial mapping relationship between the global coordinate system and the tibial local coordinate system.

[0128] Specifically, for the femoral ligament attachment point position, intercondylar notch apex position and femoral head center position in the femoral local coordinate system, combined with the femoral transformation matrix, the femoral ligament attachment point position, intercondylar notch apex position and femoral head center position are converted to the global coordinate system through inverse transformation. For the tibial ligament attachment point position, tibial plateau center position and ankle joint center position in the tibial local coordinate system, combined with the tibial transformation matrix, the tibial ligament attachment point position, tibial plateau center position and ankle joint center position are converted to the global coordinate system through inverse transformation.

[0129] Furthermore, during knee flexion, dynamic points in the femoral and tibia local coordinate systems are converted to the global coordinate system to uniformly observe the relative motion of the femur and tibia. The femoral and tibia local coordinate systems rotate and translate with movement (for example, the femur rotates around the center of the knee joint during knee flexion). Therefore, local coordinates (such as the center of the femoral head) must be converted to global coordinates to track their actual positions in space.

[0130] The ligament isometric analysis method provided in the embodiment of the present application can accurately evaluate the rationality of the ligament attachment points through precise determination of key positions of the knee joint, coordinate system conversion, and data calculation and analysis. It effectively solves the problem of poor surgical results caused by inaccurate determination of the ligament attachment point positions in anterior cruciate ligament reconstruction surgery in the prior art, improves the accuracy and reliability of surgical planning, and thus improves the success rate of anterior cruciate ligament reconstruction surgery.

[0131] Based on the same inventive concept, a ligament isometric analysis device corresponding to the ligament isometric analysis method is also provided in the embodiment of the present application. Since the principle of solving the problem by the device in the embodiment of the present application is similar to the above-mentioned ligament isometric analysis method in the embodiment of the present application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0132] See also Figure 6 , Figure 6 This is a schematic diagram of the structure of a ligament isometric analysis device provided in an embodiment of the present application. Figure 6 As shown in , the apparatus 600 includes:

[0133] The data acquisition module 601 is used to determine the femoral ligament insertion point position, the intercondylar notch vertex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, and the knee joint registration point position set in the image coordinate system based on the original image data of the knee joint;

[0134] A first processing module 602 is configured to determine the center position of the femoral head based on the acquired position set of the femoral positioning device during the femoral rotation process, and determine the center position of the ankle joint based on the acquired medial and lateral malleolus positions;

[0135] A coordinate system alignment module 603 is configured to convert the femoral ligament insertion point, intercondylar notch apex, tibial ligament insertion point, and tibial plateau center position in the image coordinate system from the image coordinate system to the local coordinate system based on a registration relationship between the image coordinate system and the local coordinate system; and to convert the femoral head center position and ankle joint center position in the global coordinate system from the global coordinate system to the local coordinate system based on a mapping relationship between the global coordinate system and the local coordinate system; wherein the registration relationship is determined based on a set of knee joint positioning device positions and a set of knee joint registration point positions, and the tibial plateau center position is determined based on the medial edge point position and the lateral edge point position of the tibial plateau;

[0136] A coordinate system conversion module 604 is used to convert the acquired femoral ligament insertion point position, intercondylar notch apex position, tibial ligament insertion point position, tibial plateau center position, femoral head center position, and ankle joint center position in the local coordinate system to the global coordinate system during knee flexion movement;

[0137] The second processing module 605 is configured to determine the flexion angle of the knee joint during the flexion movement based on the intercondylar notch apex position, the tibial plateau center position, the femoral head center position, and the ankle joint center position in the global coordinate system, and determine the ligament lengths corresponding to different flexion angles based on the femoral ligament insertion point position and the tibial ligament insertion point position in the global coordinate system, and compare the ligament lengths with the reference ligament lengths to obtain ligament length differences corresponding to different flexion angles;

[0138] The isometric analysis module 606 is used to construct a ligament isometric curve showing the difference in ligament length as a function of knee flexion angle, so as to evaluate the rationality of the ligament insertion point based on the ligament isometric curve.

[0139] The ligament isometric analysis device provided in the embodiment of the present application first aligns the coordinate system and then analyzes the position changes obtained by the knee flexion movement in the local coordinate system. It can accurately capture the dynamic changes of the ligament attachment points during the knee joint movement, and construct a ligament isometric curve of the ligament length difference as the knee flexion angle changes by simulating the dynamic changes of the knee joint during the knee flexion movement. The rationality of the ligament attachment points is evaluated by the ligament isometric curve, which improves the accuracy of determining the position of the ligament attachment points, thereby ensuring the rationality of the position of the ligament attachment points, and helping to improve the success rate of anterior cruciate ligament reconstruction surgery.

[0140] See also Figure 7 , Figure 7 This is a schematic diagram of the structure of a ligament isometric analysis system provided in an embodiment of the present application. Figure 7As shown in , the system includes: a visual device 1, a knee joint positioning device, a mobile positioning device 4 and a processing device 5. The visual device 1 is used to collect the position set of the knee joint positioning device and the position information of the mobile positioning device 4. The visual device 1 is connected to the processing device 5.

[0141] Specifically, the knee joint positioning device includes a femoral positioning device 2 and a tibial positioning device 3. The femoral positioning device 2 is fixed on the femur, and the tibial positioning device 3 is fixed on the tibia.

[0142] Optionally, the visual device 1 is used to monitor the knee joint positioning device and the mobile positioning device 4, thereby collecting the position set of the knee joint positioning device and the position information of the mobile positioning device 4. Furthermore, the knee joint positioning device is further subdivided into the femoral positioning device 2 and the tibial positioning device 3, and the visual device is used to collect the position set of the femoral positioning device 2 and the position set of the tibial positioning device 3. The visual device 1 is typically a device based on optical principles, such as an optical locator.

[0143] Specifically, both the femoral positioning device 2 and the tibial positioning device 3 are devices with optical markers. These optical markers can be accurately identified and tracked by the visual device 1. In actual application, the femoral positioning device 2 is stably fixed to the femur. For example, a stable connection can be achieved by using Kirschner wires, thereby ensuring that the femoral positioning device 2 and the femur remain relatively stationary during knee joint movement, thereby truly reflecting the position and posture changes of the femur. Similarly, the tibial positioning device 3 is fixed to the tibia and is used to collect position information of the tibia.

[0144] Optionally, the mobile positioning device 4 is mainly used to collect the position information of some specific parts, such as the position of the medial malleolus and the lateral malleolus. It can be a handheld positioning device with a sensor, such as an electromagnetic locator, an optical positioning probe, etc. During operation, the operator can hold the mobile positioning device 4 and touch or approach the medial malleolus, lateral malleolus, etc. with its probe. The mobile positioning device 4 can obtain the three-dimensional coordinate information of the medial malleolus and the lateral malleolus through the internal sensor. The mobile positioning device 4 is provided with an optical marking point so that the visual device can collect the position information of the mobile positioning device 4 through visual recognition technology. Furthermore, the processing device 5 receives data from the visual device 1. The processing device 5 can be a computer, server, or other device with powerful data processing capabilities. It stores, analyzes, and calculates the received data, and performs a series of complex calculation tasks such as determining the center position of the femoral head using a random sampling consistency algorithm, performing coordinate transformation based on the alignment relationship, calculating the ligament length difference, and constructing the ligament isometric curve, and finally outputs an evaluation result of the rationality of the ligament insertion point.

[0145] The ligament isometric analysis system provided in the embodiment of the present application can comprehensively and accurately obtain the overall position of the femur and tibia, as well as the position of key anatomical points. The data is more comprehensive and accurate, and can complete complex knee joint position information analysis tasks in a relatively short period of time, while ensuring the accuracy of the analysis results. It uses visual devices and positioning devices (such as femoral positioning device 2, tibial positioning device 3 and mobile positioning device 4) to simulate the isometric curve of the ligament, thereby analyzing the feasibility of the bone tunnel plan, helping doctors to adjust the bone tunnel plan, improving the efficiency and quality of surgical planning, and ensuring the success of the operation.

[0146] See also Figure 8 , Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 8 As shown in FIG, the electronic device 800 includes a processor 801, a memory 802 and a bus 803.

[0147] The memory 802 stores machine-readable instructions executable by the processor 801. When the electronic device 800 is running, the processor 801 communicates with the memory 802 via the bus 803. When the machine-readable instructions are executed by the processor 801, the above-mentioned Figure 1 as well as Figure 5 The specific implementation of the steps of the ligament isometric analysis method in the method embodiment shown can be found in the method embodiment and will not be repeated here.

[0148] The embodiment of the present application also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the computer program can execute the above-mentioned Figure 1 as well as Figure 5 The specific implementation of the steps of the ligament isometric analysis method in the method embodiment shown can be found in the method embodiment and will not be repeated here.

[0149] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0150] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. There may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed may be through some communication interface, indirect coupling or communication connection of devices or units, which may be electrical, mechanical or other forms.

[0151] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0152] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0153] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0154] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The scope of protection of the present application is not limited thereto. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-mentioned embodiments within the technical scope disclosed in the present application, or perform equivalent replacements for some of the technical features thereof. These modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A ligament isometric analysis method, characterized in that: The method comprises: According to the original image data of the knee joint, the femoral ligament insertion point position, the intercondylar notch apex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau and the knee joint registration point position set are determined in the image coordinate system; Determine the center position of the femoral head based on the acquired position set of the femoral positioning device during the femoral rotation process, and determine the center position of the ankle joint based on the acquired medial malleolus position and lateral malleolus position; According to the registration relationship between the image coordinate system and the local coordinate system, the femoral ligament insertion point position, the intercondylar notch apex position, the tibial ligament insertion point position and the tibial plateau center position in the image coordinate system are converted from the image coordinate system to the local coordinate system; according to the mapping relationship between the global coordinate system and the local coordinate system, the femoral head center position and the ankle joint center position in the global coordinate system are converted from the global coordinate system to the local coordinate system; wherein the registration relationship is determined based on the position set of the knee joint positioning device and the knee joint registration point position set, and the tibial plateau center position is determined based on the medial edge point position and the lateral edge point position of the tibial plateau; During the knee flexion movement, the femoral ligament insertion point position, intercondylar notch apex position, tibial ligament insertion point position, tibial plateau center position, femoral head center position and ankle joint center position obtained in the local coordinate system are converted from the local coordinate system to the global coordinate system; The knee flexion angle during knee flexion is determined based on the intercondylar notch apex position, tibial plateau center position, femoral head center position, and ankle joint center position in the global coordinate system. The ligament length corresponding to different knee flexion angles is determined based on the femoral ligament insertion point position and tibial ligament insertion point position in the global coordinate system. The ligament length difference corresponding to different knee flexion angles is obtained by comparison with the reference ligament length. A ligament isometric curve showing the difference in ligament length as a function of knee flexion angle was constructed to evaluate the rationality of the ligament insertion point based on the ligament isometric curve.

2. The method according to claim 1, characterized in that The knee joint positioning device includes a femoral positioning device and a tibial positioning device, wherein the femoral positioning device is fixed on the femur and the tibial positioning device is fixed on the tibia; The method of determining the femoral ligament insertion point position, the intercondylar notch vertex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, and the knee joint registration point position set in the image coordinate system based on the original image data of the knee joint includes: According to the original image data of the knee joint, the femoral ligament insertion point position, the intercondylar notch vertex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, the femoral registration point position set, and the tibial registration point position set are determined in the image coordinate system; The method converts the femoral ligament insertion point, intercondylar notch vertex position, tibial ligament insertion point and tibial plateau center position in the image coordinate system from the image coordinate system to the local coordinate system according to the registration relationship between the image coordinate system and the local coordinate system, and converts the femoral head center position and ankle joint center position in the global coordinate system from the global coordinate system to the local coordinate system according to the mapping relationship between the global coordinate system and the local coordinate system, including: According to the femoral registration relationship between the image coordinate system and the femoral local coordinate system, the femoral ligament attachment point position and the intercondylar notch vertex position are converted from the image coordinate system to the femoral local coordinate system; according to the tibial registration relationship between the image coordinate system and the tibial local coordinate system, the tibial ligament attachment point position and the tibial plateau center position are converted from the image coordinate system to the tibial local coordinate system; according to the femoral mapping relationship between the global coordinate system and the femoral local coordinate system, the femoral head center position in the global coordinate system is converted from the global coordinate system to the femoral local coordinate system; according to the tibial mapping relationship between the global coordinate system and the tibial local coordinate system, the ankle joint center position in the global coordinate system is converted from the global coordinate system to the tibial local coordinate system; wherein, the femoral registration relationship is determined according to the position set of the femoral positioning device and the femoral registration point position set, and the tibial registration relationship is determined according to the position set of the tibial positioning device and the tibial registration point position set; During the knee flexion movement, the femoral ligament attachment point position, intercondylar notch apex position, tibial ligament attachment point position, tibial plateau center position, femoral head center position and ankle joint center position acquired in the local coordinate system are converted from the local coordinate system to the global coordinate system, including: During knee flexion, the femoral ligament attachment point, intercondylar notch apex position and femoral head center position obtained in the femoral local coordinate system are converted from the femoral local coordinate system to the global coordinate system according to the femoral mapping relationship between the global coordinate system and the femoral local coordinate system. The tibial ligament attachment point, tibial plateau center position and ankle joint center position obtained in the tibial local coordinate system are converted from the tibial local coordinate system to the global coordinate system according to the tibial mapping relationship between the global coordinate system and the tibial local coordinate system.

3. The method according to claim 2, characterized in that The femoral registration relationship and the tibial registration relationship are determined by the following steps: Calculate the femoral transformation matrix and the tibial transformation matrix according to the posture returned by the femoral positioning device and the posture returned by the tibial positioning device respectively; Determine a mapped femoral position set of the femoral positioning device in a femoral local coordinate system based on the femoral transformation matrix and the position set of the femoral positioning device; determine a mapped tibial position set of the tibial positioning device in a tibial local coordinate system based on the tibial transformation matrix and the position set of the tibial positioning device; constructing a femoral registration matrix according to the mapped femoral position set and the femoral registration point position set, so as to characterize the femoral registration relationship through the femoral registration matrix; constructing a tibia registration matrix according to the mapped tibia position set and the tibia registration point position set, so as to represent the tibia registration relationship through the tibia registration matrix; And, determining the femur mapping relationship and the tibia mapping relationship by the following steps: Calculating a femoral transformation matrix according to the posture returned by the femoral positioning device, so as to represent the femoral mapping relationship through the femoral transformation matrix; A tibial transformation matrix is ​​calculated according to the position and posture returned by the tibial positioning device, so as to represent the tibial mapping relationship through the tibial transformation matrix.

4. The method according to claim 1, wherein The method of determining the center position of the femoral head according to the acquired position set of the femoral positioning device during the femoral rotation process, and determining the center position of the ankle joint according to the acquired medial malleolus position and lateral malleolus position, comprises: Obtaining three-dimensional position coordinates of a femoral positioning device during femoral rotation to form a position set; Determining the femoral head center position using a random sampling consensus algorithm based on the position set; According to the obtained medial and lateral malleolus positions, the center position of the ankle joint is calculated using the midpoint formula.

5. The method according to claim 2, characterized in that The method of determining the femoral ligament insertion point position, the intercondylar notch vertex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, the femoral registration point position set, and the tibial registration point position set in the image coordinate system based on the original image data of the knee joint includes: Determine the femur segmentation model and the tibia segmentation model according to the original image data of the knee joint; Obtaining the femoral ligament insertion point position and the intercondylar notch vertex position in the image coordinate system from the femoral segmentation model, and obtaining the tibial ligament insertion point position, the medial edge point position of the tibial plateau, and the lateral edge point position of the tibial plateau in the image coordinate system from the tibial segmentation model; Feature points are selected on the surface of the femur segmentation model to form a femur registration point position set, and feature points are selected on the surface of the tibia segmentation model to form a tibia registration point position set.

6. The method according to claim 1, characterized in that The method comprises determining the knee flexion angle during knee flexion according to the intercondylar notch apex position, the tibial plateau center position, the femoral head center position, and the ankle joint center position in the global coordinate system, determining the ligament lengths corresponding to different knee flexion angles according to the femoral ligament attachment point position and the tibial ligament attachment point position in the global coordinate system, and comparing the ligament lengths with the reference ligament lengths to obtain ligament length differences corresponding to different knee flexion angles, including: The femoral mechanical axis is determined according to the center position of the femoral head and the apex position of the intercondylar notch in the global coordinate system, and the tibial mechanical axis is determined according to the center position of the tibial plateau and the center position of the ankle joint in the global coordinate system; Calculating the knee flexion angle during the knee flexion movement using a vector angle formula according to the femoral mechanical axis and the tibial mechanical axis; According to the femoral ligament insertion point position and tibial ligament insertion point position in the global coordinate system, the ligament length corresponding to different knee flexion angles was calculated using the three-dimensional distance formula; The differences between the ligament lengths corresponding to different knee flexion angles and the reference ligament lengths corresponding to the specified knee flexion angles are calculated to obtain the ligament length differences corresponding to different knee flexion angles.

7. The method according to claim 1, characterized in that The step of constructing a ligament isometric curve showing changes in ligament length differences with knee flexion angles, and evaluating the rationality of ligament insertion points based on the ligament isometric curve, includes: Construct the ligament isometric curve showing the difference in ligament length as the knee flexion angle changes; If the ligament length difference is within a preset length difference range, it is determined that the ligament attachment point is reasonable.

8. A ligament isometric analysis device, characterized in that: The device comprises: a data acquisition module, configured to determine, based on the original image data of the knee joint, the femoral ligament insertion point position, the intercondylar notch apex position, the tibial ligament insertion point position, the medial edge point position of the tibial plateau, the lateral edge point position of the tibial plateau, and the knee joint registration point position set in the image coordinate system; a first processing module, configured to determine the center position of the femoral head according to the acquired position set of the femoral positioning device during the femoral rotation process, and determine the center position of the ankle joint according to the acquired medial malleolus position and lateral malleolus position; a coordinate system alignment module for converting the femoral ligament insertion point, intercondylar notch apex, tibial ligament insertion point, and tibial plateau center position in the image coordinate system from the image coordinate system to the local coordinate system based on a registration relationship between the image coordinate system and the local coordinate system, and for converting the femoral head center position and ankle joint center position in the global coordinate system from the global coordinate system to the local coordinate system based on a mapping relationship between the global coordinate system and the local coordinate system; wherein the registration relationship is determined based on a position set of a knee joint positioning device and a position set of knee joint registration points, and the tibial plateau center position is determined based on a medial edge point position and a lateral edge point position of the tibial plateau; A coordinate system conversion module is used to convert the acquired femoral ligament insertion point position, intercondylar notch apex position, tibial ligament insertion point position, tibial plateau center position, femoral head center position and ankle joint center position from the local coordinate system to the global coordinate system during knee flexion movement; The second processing module is used to determine the knee flexion angle during the knee flexion movement based on the intercondylar notch apex position, the tibial plateau center position, the femoral head center position and the ankle joint center position in the global coordinate system, and determine the ligament length corresponding to different knee flexion angles based on the femoral ligament insertion point position and the tibial ligament insertion point position in the global coordinate system, so as to compare with the reference ligament length to obtain the ligament length difference corresponding to the different knee flexion angles; The isometric analysis module is used to construct a ligament isometric curve showing the difference in ligament length as the knee flexion angle changes, so as to evaluate the rationality of the ligament insertion point based on the ligament isometric curve.

9. A ligament isometric analysis system, characterized in that: The system includes: a visual device, a knee joint positioning device, a mobile positioning device and a processing device, the visual device is used to collect the position set of the knee joint positioning device and the position information of the mobile positioning device, the visual device is connected to the processing device, the knee joint positioning device includes a femoral positioning device and a tibial positioning device, the femoral positioning device is fixed on the femur, and the tibial positioning device is fixed on the tibia, the mobile positioning device is used to measure the medial malleolus position and the lateral malleolus position, and the processing device is used to execute the ligament isometric analysis method as described in any one of claims 1 to 7.

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