WO2025200291A1 - Dynamic simulation and isometric analysis method and system for ligament - Google Patents

Abstract

The present invention relates to the technical field of ligament simulation analysis. Provided is a dynamic simulation and isometric analysis method for a ligament, the method comprising: S1: respectively selecting a ligament origin and a ligament insertion from surfaces of a bone of origin and a bone of insertion, which are connected by a current ligament; S2: connecting the ligament origin and the ligament insertion to form a rotation axis, and acquiring a plurality of cross-sectional planes passing through the rotation axis; S3: for each cross-sectional plane, acquiring an admissible region where a three-dimensional connection line of the current ligament can be established, calculating in the admissible region a set of feasible lines through which the current ligament can pass, and calculating the shortest three-dimensional path on the basis of the set of feasible lines; and S4: constructing a ligament length set on the basis of the shortest three-dimensional paths calculated from all of the cross-sectional planes, and taking from the length set the shortest path as a three-dimensional spatial path of the current ligament at the current moment. A ligament length during a movement process can be quickly calculated to realize ligament simulation, and three-dimensional ligament length information can be obtained without the need for a large amount of simulation analysis.

Description

A ligament dynamic simulation and isometric analysis method and system Technical Field

The present invention relates to the technical field of ligament simulation analysis, and in particular to a ligament dynamic simulation and isometric analysis method and system.

Background Art

Ligaments are important structures that maintain stability in the body's joints. They are connective tissues that connect bones and are crucial for the stability and function of the body's joints. Here are some key facts about the importance of ligaments in maintaining joint stability:

Connecting Bones: Ligaments are connective tissues made of fibers that connect one bone to another. They surround joints, forming the joint capsule and providing structural support between bones through bundles of fibers.

Maintaining joint stability: One of the main functions of ligaments is to maintain the stability of bone joints. Ligaments prevent excessive movement or dislocation of joints during exercise by resisting the tensile and torsional forces around the joints.

Transmitting force: Ligaments transmit force during movement and activity. They help share the body's load, allowing the body to maintain balance and coordination during movement and activity.

Sensing joint position: Ligaments also work with the nervous system to help the body sense and adjust its position in space by sensing signals about joint position and range of motion.

Injury and Rehabilitation: Due to their importance, ligament injuries can affect joint stability and function. Rehabilitation and treatment often include an emphasis on ligament restoration and strengthening.

Analyzing ligament length during motion can help assess the biomechanical behavior of ligaments during movement, aiding clinical surgical planning and risk assessment. Dynamic X-rays can be used to analyze joint motion, but traditional X-rays cannot visualize ligaments and other tissues. Simulating ligaments will further expand the clinical application of X-rays for ligaments and other soft tissues.

In the prior art, in order to achieve ligament measurement, the following methods are usually adopted:

(1) Guenoun et al. published a study in the journal Surgical and Radiologic Anatomy in 2017 titled “Dynamic study of the anterior cruciate ligament of the knee using open MRI”. Vibration information is used to reconstruct ligament models and map their three-dimensional condition, which is extremely accurate and can reflect the morphology of the ligaments. However, capturing MRI information from multiple body positions to reconstruct ligament models, while accurate, is time-consuming and impractical for scalability. Furthermore, it cannot reflect the load conditions of joints under weight-bearing conditions.

(2) Hang Xu’s 2015 paper, “An Improved OpenSim Gait Model with Multiple Degrees of Freedom for the Knee Joint and Ligaments,” published in the journal Applications of Computational Methods in Biomechanics and Biomedical Engineering, used a linear model to measure the linear distance between ligaments based on human motion captured by light. This model is a functional motion under load-bearing conditions and can measure ligament information under different motions. However, the linear model cannot reflect the ligament distance under the actual knee joint geometry based on human motion captured by light, and the accuracy cannot be guaranteed.

Summary of the Invention

In response to the above problems, the purpose of the present invention is to provide a ligament dynamic simulation and isometric analysis method and system, which can quickly calculate the ligament length during movement to achieve ligament simulation, and obtain three-dimensional ligament length information without a large amount of simulation analysis.

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

A ligament dynamic simulation and isometric analysis method, comprising:

S1: Based on the three-dimensional model of the bone joint, select the current ligament starting point and ligament ending point on the surface of the starting bone and ending bone to which the current ligament is connected for dynamic simulation;

S2: connecting the starting point of the ligament and the ending point of the ligament to form a rotation axis, and obtaining a plurality of cross-sectional planes passing through the rotation axis;

S3: for any of the cross-sectional planes, respectively, obtaining a passable region capable of establishing a three-dimensional connection line of the current ligament, calculating a set of connected lines through which the current ligament can pass within the passable region, and calculating the shortest three-dimensional path from the starting point of the ligament to the ending point of the ligament based on the set of connected lines;

S4: constructing a ligament length set based on the shortest three-dimensional paths calculated on all the cutting planes, and taking the shortest three-dimensional path in the ligament length set as the three-dimensional spatial path of the current ligament at the current moment.

S5: Select multiple ligament termination points on the termination bone surface and repeat step S2 - S4 calculates the three-dimensional spatial path based on the different ligament end points, finds all the ligament end points whose three-dimensional spatial paths are shorter than a preset length to draw contour lines, and the range corresponding to the contour lines is the equal length interval required to construct the current ligament;

S6: Set different weights for all the three-dimensional spatial paths in the equal-length interval, calculate the weighted center point in the equal-length interval based on the weights, the three-dimensional spatial path corresponding to the weighted center point is the most equal-length point of the current ligament, and the most equal-length point is the final spatial path of the current ligament.

Furthermore, in step S1, based on the three-dimensional model of the bone joint, the ligament starting point and the ligament ending point at the current moment are respectively selected on the surfaces of the starting bone and the ending bone to which the current ligament to be dynamically simulated is connected, specifically:

S11: establishing three-dimensional surface models of the starting bone and the ending bone connected to the current ligament, respectively, wherein the point set formed by the three-dimensional surface model of the starting bone is recorded as a three-dimensional point set P _start , and the point set formed by the three-dimensional surface model of the ending bone is recorded as a three-dimensional point set P _end ;

S12: The ligament starting point at the initial moment is recorded as L _start , and the ligament ending point is recorded as L _end , and the motion conversion matrix T _start and the motion conversion matrix T _end of the starting bone and the ending bone from the initial moment to the current moment T are respectively obtained, and the motion conversion matrix T _start and the motion conversion matrix T _end are used to convert the ligament starting point L _start and the ligament ending point L _end to the ligament starting point L start at the current moment T and the ligament termination point

Furthermore, in step S2, the ligament starting point and the ligament ending point are connected to form the rotation axis, and a plurality of cross-sectional planes passing through the rotation axis are obtained, specifically:

S21: connecting the starting point of the ligament and the ending point of the ligament to form a line segment V;

S22: Rotate the line segment V as the rotation axis multiple times by an angle α to generate a plurality of cross-sectional planes passing through the rotation axis until the cross-sectional planes uniformly cover the rotation range of 0-180 degrees, wherein the angle α is set according to the accuracy of simulating the current ligament.

Furthermore, in step S3, the passable area capable of establishing the three-dimensional connection line of the current ligament is obtained for any of the section planes, specifically:

The number of the cutting planes is recorded as n. For any of the cutting planes, the cutting plane is compared with The set of intersection points of the three-dimensional surface model of the starting bone and the ending bone is recorded as and Where i ranges from 1 to n;

At this time, the set range of the intersection is defined and The bone tissue portion inside the cavity is the impassable area, and the area other than the bone tissue portion is the passable area;

The calculated three-dimensional connection line of the current ligament is the curve connection line within the passable area.

Furthermore, in step S3, the set of connected lines through which the current ligament can pass is calculated within the passable area, specifically:

Dividing the bones around the joints using a plurality of polygons on the section plane, each of the polygons being composed of a set of nodes and edges;

For each of the nodes in all of the polygons, connect each of the nodes in all of the polygons to form a plurality of node lines;

A plurality of node lines are judged respectively. If the node line intersects with any of the polygons, it does not constitute the connected line; otherwise, it is added to the set of connected lines.

Furthermore, in step S3, the shortest three-dimensional path from the ligament starting point to the ligament ending point is calculated based on the set of connected lines, specifically:

S31: Initializing an open list for storing the path that the current ligament is about to take and a closed list for storing the path that the current ligament has already taken;

S32: Add the ligament starting point to the open list;

S33: When the open list is not empty, taking the last node on the path with the minimum cost of the adjacent points that has been calculated from the open list and adding it to the closed list as the current node, wherein when step S33 is executed for the first time, the current node is the starting point of the ligament; when step S33 is not executed for the first time, the current node is the last node on the path with the minimum cost of the adjacent points that has been calculated;

S34: Determine whether the current node is the ligament termination point. If it is the ligament termination point, the algorithm ends and jumps directly to step S37;

S35: Obtain all the next nodes adjacent to the current node according to the connected lines in the set, and calculate the adjacent distances from the ligament starting point to all the next nodes respectively. point cost, and if the adjacent next node is not in the open list and the closed list, add the adjacent next node to the open list;

S36: In the open list, update the adjacent point costs from the ligament starting point to all the next nodes, and determine whether the current node is the ligament ending point. If it is the ligament ending point, the algorithm ends and jumps directly to step S37; otherwise, jumps to step S33 to continue executing the current algorithm;

S37: Output all the nodes from the starting point of the ligament to the ending point of the ligament from the closed list, and record them as the shortest three-dimensional path.

Furthermore, the adjacent point cost _Fligament is calculated using the Euclidean distance formula, specifically:

F _ligament = G + H

Among them, G is the actual cost, that is, the path that has been traveled from the starting point of the ligament to the current node, and H is the estimated cost and the estimated path to be traveled from the current node to the next node adjacent to the current node.

A ligament dynamic simulation and isometric analysis system for performing the above-mentioned ligament dynamic simulation and isometric analysis method comprises:

A ligament starting and ending point selection module is used to select the starting point and ending point of the ligament at the current moment on the surface of the starting bone and ending bone to which the current ligament is connected that needs to be dynamically simulated based on the three-dimensional model of the bone joint;

a ligament section plane acquisition module, configured to connect the ligament starting point and the ligament ending point to form a rotation axis, and acquire a plurality of section planes passing through the rotation axis;

a cross-sectional path calculation module, configured to obtain, for any of the section planes, a passable region capable of establishing a three-dimensional connection line of the current ligament, calculate within the passable region a set of connected lines through which the current ligament can pass, and calculate, based on the set of connected lines, a shortest three-dimensional path from a starting point of the ligament to an ending point of the ligament;

A spatial path acquisition module is used to construct a ligament length set based on the shortest three-dimensional paths calculated on all the cutting planes, and take the shortest shortest three-dimensional path in the ligament length set as the three-dimensional spatial path of the current ligament at the current moment.

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

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

(1) A ligament dynamic simulation and isometric analysis method is provided, comprising: S1: based on a three-dimensional model of a bone joint, selecting the ligament starting point and ligament ending point at the current moment on the surface of the starting bone and ending bone to which the current ligament to be dynamically simulated is connected; S2: connecting the ligament starting point and the ligament ending point to form a rotation axis, and obtaining a plurality of cross-sectional planes passing through the rotation axis; S3: for any of the cross-sectional planes, obtaining a passable area that can establish a three-dimensional connection line of the current ligament, calculating a set of connected lines that the current ligament can pass through in the passable area, and calculating the shortest three-dimensional path from the ligament starting point to the ligament ending point based on the set of connected lines; S4: constructing a ligament length set based on the shortest three-dimensional paths calculated on all the cross-sectional planes, and taking the shortest one of the shortest three-dimensional paths in the ligament length set as the three-dimensional spatial path of the current ligament at the current moment. The above technical solution is fast in calculation and can obtain three-dimensional ligament length information without the need for a large amount of simulation analysis. Based on the set of connected lines of the constructed nodes, the problem of excessive computational complexity caused by too many nodes in the three-dimensional patch model is reduced, and three-dimensional calculations can be realized.

(2) The present invention simplifies the construction process of a three-dimensional visual map, further reduces the computational complexity of the three-dimensional visual map, optimizes the computational process, and enables three-dimensional analysis of multiple ligaments. Furthermore, the present invention can perform calculations based on any input three-dimensional joint motion, enabling analysis of the dynamic length of ligaments under load.

(3) The present invention is universal in all scenarios. Whether using individualized models, magnetic resonance imaging, or optical capture of joint motion data, it can calculate the three-dimensional path of the ligament based on the three-dimensional skeletal information. It has wide versatility and can analyze load-bearing position data. The data is accurate, and the calculated ligament length is a non-linear ligament distance, which can comprehensively consider the joint geometry.

(4) The present invention can calculate the equal length area of the ligament through multiple points within a preset range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an overall flow chart of the ligament dynamic simulation and isometric analysis method of the present invention;

FIG2 is a three-dimensional schematic diagram of a cross-sectional plane of the present invention;

FIG3 is a schematic diagram of a skeleton divided into two polygons according to the present invention;

FIG4 is a two-dimensional schematic diagram of a cross-sectional plane of the present invention;

FIG5 is a schematic diagram illustrating an example of the Euclid algorithm of the present invention;

FIG6 is a schematic diagram of the shortest three-dimensional path found by the present invention;

FIG7 is a schematic diagram of calculating the shortest three-dimensional path of the current cutting plane for each cutting plane according to the present invention;

FIG8 is a schematic diagram of selecting multiple ligament termination points on the termination bone surface according to the present invention;

FIG9 is a schematic diagram of the equal-length interval arrangement of the present invention;

FIG10 is an overall structural diagram of the ligament dynamic simulation and isometric analysis system of the present invention.

DETAILED DESCRIPTION

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

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

First embodiment

As shown in FIG1 , this embodiment provides a ligament dynamic simulation and isometric analysis method, including:

S1: Based on the three-dimensional model of the bone joint, the starting point and the ending point of the ligament at the current moment are respectively selected on the surface of the starting bone and the ending bone to which the current ligament is connected that needs to be dynamically simulated.

Ligaments are joints that connect two bones, including the starting bone and the ending bone. Before performing ligament dynamic simulation, you need to do the following:

S11: respectively establishing 3D surface models of the start bone and the end bone connected to the current ligament, wherein the point set formed by the 3D surface model of the start bone is recorded as 3D point set P _start , and the point set formed by the 3D surface model of the end bone is recorded as 3D point set P _end .

S12: The ligament starting point at the initial moment is recorded as L _start , and the ligament ending point is recorded as L _end , and the motion conversion matrix T _start and the motion conversion matrix T _end of the starting bone and the ending bone from the initial moment to the current moment T are respectively obtained, and the motion conversion matrix T _start and the motion conversion matrix T _end are used to convert the ligament starting point L _start and the ligament ending point L _end to the ligament starting point L start at the current moment T and the ligament termination point

The conversion formula of the ligament starting point and ligament ending point through the motion conversion matrix is:

For the two motion conversion matrices T _start and T _end , it is necessary to rely on the pre-established coordinate system for conversion. The starting point of the ligament at the initial moment is recorded as L _start , the ending point of the ligament is recorded as L _end , and the starting point of the ligament at the current moment T is recorded as L end . and the ligament termination point All are represented by coordinates, but it should be noted that this embodiment does not limit the specific method of establishing the coordinate system. It only requires that the established coordinate system can mark the coordinates of all points and complete the coordinate conversion according to the motion transformation matrix.

S2: connecting the ligament starting point and the ligament ending point to form a rotation axis, and obtaining a plurality of cross-sectional planes passing through the rotation axis.

In this embodiment, several cross-sectional planes passing through the rotation axis are obtained, specifically:

S21: Connect the starting point of the ligament and the ending point of the ligament to form a line segment V.

S22: Rotate the line segment V as the rotation axis multiple times by an angle α to generate a plurality of cross-sectional planes passing through the rotation axis, until the cross-sectional planes evenly cover the rotation range of 0-180 degrees.

The angle α is set according to the accuracy of the simulation of the current ligament. When the simulation accuracy is high and the calculation speed is low, the value of the rotation angle α is set to be small, such as 0.1 degrees. When the simulation accuracy is low but the calculation speed is fast, the value of the rotation angle α is set to be large. Large, such as 2 degrees, etc. As shown in FIG2 , it is a three-dimensional schematic diagram of one of the cross-sectional planes.

S3: For any one of the cutting planes, obtain a passable area that can establish a three-dimensional connection line of the current ligament, calculate a set of connected lines through which the current ligament can pass within the passable area, and calculate the shortest three-dimensional path from the starting point of the ligament to the ending point of the ligament based on the set of connected lines.

In this embodiment, the passable area capable of establishing the three-dimensional connection line of the current ligament is obtained for any of the section planes, specifically:

The number of the cutting planes is recorded as n. For any cutting plane, when it intersects with the three-dimensional surface model, the set of intersection points of the cutting plane with the three-dimensional surface model of the starting bone and the ending bone is recorded as and Where i ranges from 1 to n;

At this time, the set range of the intersection is defined and The bone tissue portion inside the cavity is the impassable area, and the area other than the bone tissue portion is the passable area;

The three-dimensional line of the current ligament that is expected to be calculated is the starting point of the ligament and ligament termination points The curve lines within the passable region are connected.

Furthermore, the set of connected lines through which the current ligament can pass is calculated within the passable region, specifically:

Calculate from the starting point of the ligament Starting with the visible area within any section plane, as shown in the two-dimensional schematic diagram of the section plane in Figure 4, the black lines represent the bone cross-sections, and the gray lines are the traversable areas of each node. The visible area is constructed as follows: the bone around the joint is divided using several polygons on the section plane. The divided polygons are recorded as {Poly ₁ , Poly ₂ ...Poly _n }. Figure 3 shows a schematic diagram of the skeleton divided into two polygons. Each polygon is composed of a set of nodes and edges {V, E}. For each node in all the polygons, each node in all the polygons is connected to form several node lines. Each of the node lines is judged separately. If the node line intersects any polygon, it does not constitute a connected line; otherwise, it is added to the set of connected lines. The set of all connected lines constitutes the visible area.

Furthermore, the shortest three-dimensional path from the ligament starting point to the ligament ending point is calculated based on the set of connected lines, specifically:

Calculate from the starting point of the ligament To the end point of the ligament The shortest three-dimensional path on each cutting plane, that is, the shortest path from the starting point of the ligament on the current cutting plane To the end point of the ligament The ligament path on the 3D path has its 3D length recorded as Len ⁱ , where i is a number from 1 to n, representing the number of the section plane. In this embodiment, the shortest 3D path is obtained by calculating the adjacent point cost F _ligament in the Euclidean distance formula.

The adjacent point cost F _ligament is calculated using the Euclidean distance formula, specifically:
F _ligament = G + H

Among them, G is the actual cost, that is, the path that has been traveled from the starting point of the ligament to the current node, and H is the estimated cost and the estimated path to be traveled from the current node to the next node adjacent to the current node.

For example, as shown in the example diagram of the Euclid algorithm in Figure 5, starting from the ligament starting point To the end point of the ligament The nodes on the connected line that it can pass through are n1, n2a, n2b, and n2c. If the current node that has been calculated is n1, it is the starting point of the ligament that has been passed. The path to n1 is denoted as G. The next three different paths from n1 to n2a, n2b, and n2c are the estimated walking paths H. n1 to n2a is denoted as H1, n1 to n2b is denoted as H2, and n1 to n2c is denoted as H3. The path with the smallest adjacent point _cost F calculated from G+{H1, H2, H3} is the shortest path from the current node n1 to all the next nodes. Figure 5 shows that F=G+H2 is the shortest path. In addition, it can be seen from Figure 5 that the next node of n2b has only the ligament termination point. One, that is, the shortest three-dimensional path calculated in Figure 5 is the starting point of the ligament To n1 to n2b to the ligament termination point

In addition, the Euclidean distance between adjacent points on the path is calculated as:

Where p1 and P2 are two points on the path, p1.x and p2.x, and p1.y and p2.y are their corresponding X and Y coordinates. The sum of the distances between all pairs of points on the path is recorded as distance d.

The overall calculation process of the shortest three-dimensional path is:

S31: Initializing an open list for storing the path that the current ligament is about to take and a closed list for storing the path that the current ligament has already taken;

S32: The starting point of the ligament Add to the open list;

S33: When the open list is not empty, take the last node on the path with the smallest calculated adjacent point _cost F from the open list and add it to the closed list as the current node. When step S33 is executed for the first time, the current node is the starting point of the ligament. When step S33 is not performed for the first time, the current node is the last node on the currently calculated path with the minimum cost of the adjacent points;

S34: Determine whether the current node is the ligament termination point If the ligament ends at The algorithm ends and jumps directly to step S37;

S35: Obtain all the next nodes adjacent to the current node according to the connected lines in the set, and calculate the ligament starting points respectively The cost F _ligament to all adjacent points of the next node, and if the adjacent next node is not in the open list and the closed list, add the adjacent next node to the open list;

S36: Update the ligament starting point in the open list To all the adjacent points of the next node, the cost F _ligament , and determine whether the current node is the ligament end point If the ligament ends at If yes, the algorithm ends and jumps directly to step S37, otherwise jumps to step S33 to continue executing the current algorithm;

S37: Outputting the starting point of the ligament from the closed list To the end point of the ligament All the nodes are recorded as the shortest three-dimensional path. FIG6 is a schematic diagram of the shortest three-dimensional path found.

S4: constructing a ligament length set based on the shortest three-dimensional paths calculated on all the cutting planes, and taking the shortest three-dimensional path in the ligament length set as the three-dimensional spatial path of the current ligament at the current moment.

Specifically, in this embodiment, step S3 is repeatedly performed, as shown in FIG7 , and the shortest three-dimensional path of the current section plane is calculated for each section plane, recorded as Len ¹ , Len ² . . . Len ⁿ , to construct a ligament length set Len ^N .

Take the shortest three-dimensional path Len ^shortest in the ligament length set Len ^N , which is the shortest path from the starting point of the ligament To the end point of the ligament The three-dimensional space path at the current time T.

S5: As shown in FIG8 , a plurality of ligament termination points are selected on the termination bone surface to construct a ligament termination point set. Repeat steps S2-S4 to calculate the three-dimensional space path based on different ligament end points, and find all the ligament end points whose three-dimensional space path is less than the preset length to draw contour lines. The range corresponding to the contour lines is the equal-length interval required to construct the current ligament. The setting of the equal-length interval is shown in the gray area in Figure 9.

Specifically, the purpose of drawing contour lines and establishing the equal length intervals required for the current ligament based on the contour lines is to find a set of points where the ligament length changes minimally during exercise, so that the ligament established later is optimal.

S6: Set different weights for all the three-dimensional spatial paths in the equal-length interval, calculate the weighted center point in the equal-length interval based on the weights, the three-dimensional spatial path corresponding to the weighted center point is the most equal-length point of the current ligament, and the most equal-length point is the final spatial path of the current ligament.

The basis for setting different weights for all three-dimensional spatial paths in the equal-length interval is to set a higher weight for the point where the ligament length changes the least during the movement, so that the weighted center point finally calculated based on the weight will be closer to the point where the ligament length changes the least during the movement.

Second embodiment

As shown in FIG10 , this embodiment provides a ligament dynamic simulation and isometric analysis system for executing the ligament dynamic simulation and isometric analysis method of the first embodiment, including:

The ligament starting and ending point selection module 1 is used to select the ligament starting point and ligament ending point at the current moment on the starting bone and ending bone surfaces to which the current ligament that needs to be dynamically simulated is connected based on the three-dimensional model of the bone joint.

The ligament section plane acquisition module 2 is used to connect the ligament starting point and the ligament ending point to form a rotation axis, and acquire a plurality of section planes passing through the rotation axis.

The cross-sectional path calculation module 3 is used to obtain, for any one of the cutting planes, a passable area that can establish a three-dimensional connection line of the current ligament, calculate the set of connected lines through which the current ligament can pass within the passable area, and calculate the shortest three-dimensional path from the starting point of the ligament to the ending point of the ligament based on the set of connected lines.

The spatial path acquisition module 4 is used to construct a ligament length set based on the shortest three-dimensional paths calculated on all the cutting planes, and take the shortest three-dimensional path in the ligament length set as the three-dimensional spatial path of the current ligament at the current moment.

An equal-length interval acquisition module 5 is configured to select a plurality of ligament termination points on the termination bone surface, repeatedly execute steps S2-S4 to calculate the three-dimensional spatial path based on the different ligament termination points, and find all the ligament termination points whose three-dimensional spatial paths are less than a preset length to draw contour lines. The range corresponding to the contour lines is the equal-length interval required to construct the current ligament.

The most isometric point acquisition module 6 is used to set different weights for all the three-dimensional spatial paths in the isometric interval, and calculate the weighted center point in the isometric interval based on the weights. The three-dimensional spatial path corresponding to the weighted center point is the most isometric point of the current ligament, and the most isometric point is the final spatial path of the current ligament.

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

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

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

It should be noted that the above embodiments can be freely combined as needed. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, they can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (10)

A ligament dynamic simulation and isometric analysis method, characterized by comprising: S1: Based on the three-dimensional model of the bone joint, select the current ligament starting point and ligament ending point on the surface of the starting bone and ending bone to which the current ligament is connected for dynamic simulation; S2: connecting the starting point of the ligament and the ending point of the ligament to form a rotation axis, and obtaining a plurality of cross-sectional planes passing through the rotation axis; S3: for any of the cross-sectional planes, respectively, obtaining a passable region capable of establishing a three-dimensional connection line of the current ligament, calculating a set of connected lines through which the current ligament can pass within the passable region, and calculating the shortest three-dimensional path from the starting point of the ligament to the ending point of the ligament based on the set of connected lines; S4: constructing a ligament length set based on the shortest three-dimensional paths calculated on all the cutting planes, and taking the shortest three-dimensional path in the ligament length set as the three-dimensional spatial path of the current ligament at the current moment. The ligament dynamic simulation and isometric analysis method according to claim 1, further comprising: S5: selecting a plurality of ligament termination points on the termination bone surface, repeatedly executing steps S2-S4 to calculate the three-dimensional spatial path based on the different ligament termination points, finding all the ligament termination points whose three-dimensional spatial paths are less than a preset length to draw contour lines, wherein the range corresponding to the contour lines is the equal length interval required to construct the current ligament; S6: Set different weights for all the three-dimensional spatial paths in the equal-length interval, calculate the weighted center point in the equal-length interval based on the weights, the three-dimensional spatial path corresponding to the weighted center point is the most equal-length point of the current ligament, and the most equal-length point is the final spatial path of the current ligament. The ligament dynamic simulation and isometric analysis method according to claim 1, characterized in that in step S1, based on the three-dimensional model of the bone joint, the ligament starting point and the ligament ending point at the current moment are respectively selected on the surface of the starting bone and the ending bone to which the current ligament to be dynamically simulated is connected, specifically: S11: Establish three-dimensional surface models of the starting bone and the ending bone connected to the current ligament, wherein the point set composed of the three-dimensional surface model of the starting bone is recorded as a three-dimensional surface model. Point set P _start , the point set formed by the three-dimensional patch model of the termination bone is recorded as three-dimensional point set P _end ; S12: The ligament starting point at the initial moment is recorded as L _start , and the ligament ending point is recorded as L _end , and the motion conversion matrix T _start and the motion conversion matrix T _end of the starting bone and the ending bone from the initial moment to the current moment T are respectively obtained, and the motion conversion matrix T _start and the motion conversion matrix T _end are used to convert the ligament starting point L _start and the ligament ending point L _end to the ligament starting point L start at the current moment T and the ligament termination point The ligament dynamic simulation and isometric analysis method according to claim 1, characterized in that in step S2, the ligament starting point and the ligament ending point are connected to form the rotation axis, and a plurality of cross-sectional planes passing through the rotation axis are obtained, specifically: S21: connecting the starting point of the ligament and the ending point of the ligament to form a line segment V; S22: Rotate the line segment V as the rotation axis multiple times by an angle α to generate a plurality of cross-sectional planes passing through the rotation axis until the cross-sectional planes uniformly cover the rotation range of 0-180 degrees, wherein the angle α is set according to the accuracy of simulating the current ligament. The ligament dynamic simulation and isometric analysis method according to claim 3, characterized in that in step S3, the passable area capable of establishing the three-dimensional connection line of the current ligament is obtained for each of the section planes, specifically: The number of the cutting planes is recorded as n. For any cutting plane, the set of intersection points of the cutting plane with the three-dimensional surface model of the starting bone and the ending bone is recorded as and Where i ranges from 1 to n; At this time, the set range of the intersection is defined and The bone tissue portion inside the cavity is the impassable area, and the area other than the bone tissue portion is the passable area; The calculated three-dimensional connection line of the current ligament is the curve connection line within the passable area. The ligament dynamic simulation and isometric analysis method according to claim 1, characterized in that in step S3, the set of connected lines through which the current ligament can pass is calculated within the passable area, specifically: The bones around the joints are divided using several polygons on the section plane. Each of the polygons is composed of a set of nodes and edges; For each of the nodes in all of the polygons, connect each of the nodes in all of the polygons to form a plurality of node lines; A plurality of node lines are judged respectively. If the node line intersects with any of the polygons, it does not constitute the connected line; otherwise, it is added to the set of connected lines. The ligament dynamic simulation and isometric analysis method according to claim 6, characterized in that in step S3, the shortest three-dimensional path from the ligament starting point to the ligament ending point is calculated based on the set of connected lines, specifically: S31: Initializing an open list for storing the path that the current ligament is about to take and a closed list for storing the path that the current ligament has already taken; S32: Add the ligament starting point to the open list; S33: When the open list is not empty, taking the last node on the path with the minimum cost of the adjacent points that has been calculated from the open list and adding it to the closed list as the current node, wherein when step S33 is executed for the first time, the current node is the starting point of the ligament; when step S33 is not executed for the first time, the current node is the last node on the path with the minimum cost of the adjacent points that has been calculated; S34: Determine whether the current node is the ligament termination point. If it is the ligament termination point, the algorithm ends and jumps directly to step S37; S35: Obtain all the next nodes adjacent to the current node according to the connected lines in the set, and respectively calculate the adjacent point costs from the ligament starting point to all the next nodes. If the adjacent next node is not in the open list and the closed list, add the adjacent next node to the open list. S36: In the open list, update the adjacent point costs from the ligament starting point to all the next nodes, and determine whether the current node is the ligament ending point. If it is the ligament ending point, the algorithm ends and jumps directly to step S37; otherwise, jumps to step S33 to continue executing the current algorithm; S37: Output all the nodes from the ligament starting point to the ligament ending point from the closed list, and record them as the shortest three-dimensional path. The ligament dynamic simulation and isometric analysis method according to claim 7, characterized in that the adjacent point cost _Fligament is calculated using the Euclidean distance formula, specifically:
F _ligament = G + H Among them, G is the actual cost, that is, the path that has been traveled from the starting point of the ligament to the current node, and H is the estimated cost and the estimated path to be traveled from the current node to the next node adjacent to the current node. A ligament dynamic simulation and isometric analysis system for executing the ligament dynamic simulation and isometric analysis method according to any one of claims 1 to 8, characterized in that it comprises: A ligament starting and ending point selection module is used to select the starting point and ending point of the ligament at the current moment on the surface of the starting bone and ending bone to which the current ligament is connected that needs to be dynamically simulated based on the three-dimensional model of the bone joint; a ligament section plane acquisition module, configured to connect the ligament starting point and the ligament ending point to form a rotation axis, and acquire a plurality of section planes passing through the rotation axis; a cross-sectional path calculation module, configured to obtain, for any of the section planes, a passable region capable of establishing a three-dimensional connection line of the current ligament, calculate within the passable region a set of connected lines through which the current ligament can pass, and calculate, based on the set of connected lines, a shortest three-dimensional path from a starting point of the ligament to an ending point of the ligament; A spatial path acquisition module is used to construct a ligament length set based on the shortest three-dimensional paths calculated on all the cutting planes, and take the shortest shortest three-dimensional path in the ligament length set as the three-dimensional spatial path of the current ligament at the current moment. A computer-readable storage medium stores computer code. When the computer code is executed, the method according to any one of claims 1 to 8 is executed.