Method and device for quantifying the length of a ligament

Abstract

The application discloses a kind of ligament wrapping length quantitative method and device, comprising: obtaining knee joint scanning image, three-dimensional model reconstruction is carried out, and the bone structure of different joint group wrapped by different ligament is reconstructed step by step;Obtain the bone of the joint to be measured and obtain the start and end point of ligament on bone according to anatomical structure;Grid division is carried out to obtain finite element model, and noise interference is removed by hole filling;Obtain joint clearance and the contact surface of joint, and output contact body structure;The contact body structure is best fitted with the bone of the joint to be measured, so that both are combined on the same bone structure;When start point is located outside non-convex structure and there is bone structure obstruction, the distance between start and end point is segmented calculation, and the shortest distance between start and end point is obtained based on section method and optimization algorithm, improve the calculation accuracy of the spatial curve length of ligament wrapping.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical imaging, in particular to a ligament wrapping length quantification method and device. BACKGROUND

[0002] The anterior cruciate ligament (ACL) is an important structure for stabilizing the knee joint, which can be damaged when the stress changes sharply, and can be repaired by anterior cruciate ligament reconstruction. Postoperative complications such as joint cartilage damage or graft tearing can be caused by joint tightness or instability caused by inappropriate graft length. Therefore, accurate quantification of ligament wrapping length and preoperative determination of bone tunnel positioning will help clinicians determine treatment plans and avoid postoperative complications. Meanwhile, other ligaments of the knee joint are also related to the stability of the knee joint, and accurate quantification of ligament wrapping length is also needed in related surgeries.

[0003] Currently, the quantification of ligament spatial curve length has the following techniques:

[0004] 1) Implantable biosensor: By implanting a differential variable differential transformer and a Hall effect sensor in the body, the displacement change of the joint can be converted into a voltage change, generating a magnetic resistance, and realizing the quantification of the ligament spatial curve length under dynamic conditions. Its limitations include biological invasion and compatibility problems, and it is not clinically achievable.

[0005] 2) Virtual fiber elongation: By reconstructing a three-dimensional model of the bone using MRI and CT image data, marking the ligament attachment points, and using a single or double plane fluorescence microscope to capture the dynamic process, the change in ligament length is reflected in the relative displacement of the attachment points. Its limitations are the impact of radiation on living organisms, limited activity, and only applicable to ligaments with convex structures.

[0006] 3) Ultrasonic method: By using ultrasonic sensors to capture dynamic changes in real time, the length changes of the field of view and anatomical points can be calculated to obtain the ligament length changes. This method is only suitable for specific tissues and is not suitable for complex structures such as non-convex structures, and can only obtain local ligament length changes.

[0007] 4) Sectional method: This method uses CT scan images of precise dissection and steel wire marking of the knee ligament attachment points and direction to reconstruct a three-dimensional finite element model of the knee joint containing the anterior cruciate ligament attachment points, and connects the center points of each parallel section of the ligament. It is a relatively accurate method for quantifying ligament wrapping length ([1] Rong K, Wang HP, Wang Y, et al. Three-dimensional dynamic study of the spatial curve length of the functional bundle of the anterior cruciate ligament of the knee joint [J]. Medical Biomechanics, 2014, 29(4): 7.).

[0008] The center points of the attachment part of the ligament functional bundle and the parallel sections of the functional bundle are established by a computer tomography (CT) system and other processing systems, the lengths of the connecting center points are connected, and the curve distance between the center points of the functional bundle is fitted to obtain the spatial curve length of the ligament.

[0009] The tomographic section method used in the prior art is specifically operated by a computer tomography (CT) system and other processing systems, the center points of the attachment part of the ligament functional bundle and the parallel sections of the functional bundle are established, the lengths of the connecting center points are connected, and the curve distance between the center points of the functional bundle is fitted to obtain the spatial curve length of the ligament. The problems thereof are as follows: the current technology needs to accurately dissect the knee joint, and mark the bone stop point and the ligament by using a steel wire and a screw, so that it is difficult to study on the living body. In addition, when the flexion angle of the knee joint is too large, the ligament forms a non-convex structure, and if only the summation of the connecting lines of the geometric centers of the tomographic sections is used, the blocking effect of the bone is ignored in some cases, so that the obtained spatial curve length is inaccurate.

[0010] In summary, it is necessary to propose a quantitative method for the wrapping length of the ligament to solve the defect that the prior art cannot accurately quantify the spatial curve length of the ligament when the knee joint has a large flexion angle and forms a non-convex structure. SUMMARY

[0011] The purpose of the present application is to provide a quantitative method for the wrapping length of the ligament and a device, which solves the problem that the prior art cannot accurately quantify the spatial curve length of the ligament when the knee joint has a large flexion angle and forms a non-convex structure by applying three-dimensional CT reconstruction technology to virtually reconstruct the ligament, finding the equal-length center of the ligament around the contact surface of the bone and the ligament, and segmentally calculating, thereby improving the calculation accuracy of the spatial curve length of the ligament wrapping, and finally realizing the rapid and accurate calculation of the spatial curve length of the ligament wrapping.

[0012] The present application provides a quantitative method for the wrapping length of the ligament, which comprises:

[0013] Obtaining a knee joint scan image, performing three-dimensional model reconstruction based on the knee joint scan image, performing step-by-step reconstruction on different joint component bone structures of different ligament wrappings and outputting the reconstructed bone joint three-dimensional model;

[0014] Obtaining a joint component bone to be measured and obtaining the start and end points of the ligament on the bone according to the anatomical structure;

[0015] According to the reconstructed bone joint three-dimensional model, meshing is performed to obtain a finite element model, holes are filled to remove noise interference, and an optimized bone joint three-dimensional model is output;

[0016] An articular gap and a contact surface of the joint are obtained, and a contact body structure formed by the contact surface of the joint is output;

[0017] The contact body structure is optimally fitted with a bone to be tested to form a ligament bone model;

[0018] When a non-convex structure is generated at different flexion angles of the knee joint, it is determined whether the starting point is located inside the non-convex structure and whether there is a bone structure block between the starting and ending points of the ligament. When the starting point is located outside the non-convex structure and there is a bone structure block, the distance between the starting and ending points is calculated in sections, and the shortest distance between the starting and ending points is obtained based on the cross-section method and the optimization algorithm, that is, the length of the spatial curve of the ligament is output.

[0019] Preferably, when a non-convex structure is generated at different flexion angles of the knee joint, it is determined whether the starting point is located inside the non-convex structure and whether there is a bone structure block between the starting and ending points of the ligament.

[0020] The starting point and the ending point of the ligament are obtained, and the center point of the contact surface is confirmed;

[0021] The optimal projection position on the surface of the bone is obtained after the cross-section method and the optimization processing to serve as the end point of the arc segment;

[0022] The ligament is divided into a first arc segment at the convex part of the bone, a first straight segment and a second straight segment to the starting and ending points of the ligament, and the first arc segment, the first straight segment and the second straight segment are quantified respectively;

[0023] According to the number of bone structure blocks, the center point of the contact surface is segmented into one or more wrapping segments as the equal-length center of the ligament, and the plurality of wrapping segments at least include a first wrapping segment and a second wrapping segment;

[0024] The center point of the contact surface of the first wrapping segment is taken as a new starting point of the ligament, and the above quantitative steps are repeated to obtain a second arc segment, a third straight segment and a fourth straight segment. The sum of all arc segments and straight segments is obtained to obtain the length of the spatial curve of the ligament;

[0025] The first straight line segment is connected by the original starting point of the ligament to the starting point of the first arcuate segment, and the second straight line segment is connected by the original ending point of the ligament to the ending point of the first arcuate segment; the starting point of the arcuate segment, the midpoint of the arcuate segment and the ending point of the arcuate segment are connected to form the arcuate segment, the center of the first arcuate segment corresponds to the center point of the first contact surface, the starting point of the second arcuate segment is the center point of the first contact surface of the first wrapping segment, and the third straight line segment is connected by the ending point of the first arcuate segment to the starting point of the second arcuate segment; the fourth straight line segment is connected by the original ending point of the ligament to the ending point of the second arcuate segment.

[0026] Preferably, when the non-convex structure is generated at different flexion angles of the knee joint, it is judged whether the starting point is located inside the non-convex structure and whether there is a bone structure block between the starting and ending points of the ligament; when the starting point is located outside the non-convex structure and there is a bone structure block, the distance between the starting and ending points is calculated in sections, and the shortest distance between the starting and ending points is obtained based on the cross-section method and the optimization algorithm, that is, the length of the spatial curve of the ligament is output, including:

[0027] When the starting point of the ligament is located outside the non-convex structure and there is a bone structure block between the starting and ending points of the ligament, the bone model of the ligament to be measured is rotated, and a cross section is made through the starting and ending points of the ligament, which is perpendicular to the contact surface center point, and the two cross sections intersect at two points.

[0028] The projection angle of the cross section intersection point on the bone is set as a change amount, and the shortest path of the ligament segment bone surface is taken as an optimization target, and the best projection position of the intersection point on the bone surface is obtained as the end point of the arcuate segment through the optimization algorithm.

[0029] The two end points of the arc shape and the starting and ending points of the ligament form a first straight line segment, a second straight line segment and an arcuate segment, and the sum of the lengths of the first straight line segment, the second straight line segment and the arcuate segment is calculated to obtain the length of the spatial curve of the ligament.

[0030] Preferably, when the non-convex structure is generated at different flexion angles of the knee joint, it is judged whether the starting point is located inside the non-convex structure and whether there is a bone structure block between the starting and ending points of the ligament; when the starting point is located outside the non-convex structure and there is a bone structure block, the distance between the starting and ending points is calculated in sections, and the shortest distance between the starting and ending points is obtained based on the cross-section method and the optimization algorithm, that is, the length of the spatial curve of the ligament is output, including:

[0031] When the starting point of the ligament is located outside the non-convex structure and there is a bone structure block between the starting and ending points of the ligament, a cross section is made through the starting and ending points of the cross section, which intersects with the bone surface at two points as the end points of the arcuate segment, and the cross section satisfies the following conditions: the projection position of the contact surface center point on the cross section is located in the middle of the two intersection points, so as to meet the requirement of forming the arcuate segment; the rotation angle of the cross section through the starting and ending points is set as a change amount, and the shortest path of the ligament segment bone surface is taken as an optimization target.

[0032] After the optimal rotation angle of the cross section is determined, the two end points of the arc and the start and end points form a first straight line segment, a first straight line segment and an arc segment, and the sum is obtained as the length of the ligament spatial curve;

[0033] The current start point is the start point of the cross section, the end point is the end point of the cross section, and the contact surface center point is the midpoint of the arc segment to be formed.

[0034] Preferably, when the non-convex structure is generated at different knee flexion angles, it is determined whether the start point is located inside the non-convex structure and whether there is a bone structure block between the start and end points of the ligament. When the start point is located outside the non-convex structure and there is a bone structure block, the distance between the start and end points is calculated in segments, and the shortest distance between the start and end points is obtained based on the cross section method and the optimization algorithm, that is, the output ligament spatial curve length includes:

[0035] When the ligament start point is located outside the non-convex structure and there are multiple bone structure blocks between the ligament start and end points, multiple wrapping segments are formed, including at least a first wrapping segment and a second wrapping segment.

[0036] The first contact surface center point of the first wrapping segment is taken as a new start point of the ligament, the ligament bone model is rotated, a cross section is made through the ligament start and end points, and the two cross sections intersect at two points.

[0037] The projection angle of the cross section intersection on the bone is set as a change amount, the shortest path of the ligament segment bone surface is taken as an optimization target, and the best projection position of the intersection on the bone surface is obtained as the end point of the arc segment through the optimization algorithm.

[0038] The two end points of the arc and the start and end points of the ligament form a first straight line segment, a second straight line segment and an arc segment.

[0039] The second contact surface center point of the second wrapping segment is taken as a new start point of the ligament, and the above steps are repeated. Assuming that there are N bone structure blocks, N arc segments and N+1 straight line segments are obtained, and the sum is obtained as the length of the ligament spatial curve.

[0040] Preferably, when the non-convex structure is generated at different knee flexion angles, it is determined whether the start point is located inside the non-convex structure and whether there is a bone structure block between the start and end points of the ligament. When the start point is located outside the non-convex structure and there is a bone structure block, the distance between the start and end points is calculated in segments, and the shortest distance between the start and end points is obtained based on the cross section method and the optimization algorithm, that is, the output ligament spatial curve length includes:

[0041] When the ligament origin is outside the non-convex structure and there are multiple bone structure blocks between the ligament origin and termination, multiple wrapping segments are formed, including the origin, multiple contact surface center points and the termination, and the quantitative steps for the ligament spatial curve length when the ligament origin is outside the non-convex structure and there is one bone structure block between the ligament origin and termination are repeated by selecting a new cross-sectional origin, a midpoint of the arc segment to be formed, and a cross-sectional termination in sequence.

[0042] Preferably, the judging whether the origin is inside the non-convex structure when the knee joint flexion angle is different to generate a non-convex structure comprises:

[0043] When the ligament origin is inside the non-convex structure, there is a bone structure block for the ligament;

[0044] The first contact surface center point is taken as a new origin for the quantitative operation of the ligament spatial curve length when the ligament origin is outside the non-convex structure and there is one bone structure block between the ligament origin and termination, or the quantitative operation of the ligament spatial curve length when there are multiple bone structure blocks between the ligament origin and termination is selected according to the number of remaining contact surface center points.

[0045] The ligament spatial curve length is obtained by connecting the projection points of the original origin and the cross-sectional proximal point, and summing all arc segments and straight line segments.

[0046] Preferably, the obtaining a knee joint scan image, reconstructing a three-dimensional model based on the knee joint scan image, and step-by-step reconstructing different joint component bone structures wrapped by different ligaments and outputting a reconstructed bone joint three-dimensional model comprises:

[0047] Performing CT tomography or MRI scanning on the knee joint to output scan images;

[0048] Setting a preset threshold and separating joint bones from soft tissues by threshold segmentation, filtering the soft tissue part interfering with imaging, and retaining joint bones;

[0049] Reconstructing a three-dimensional model for the CT tomography image, step-by-step reconstructing and coloring different joint component bone structures wrapped by different ligaments, and saving them in STL format for later use.

[0050] Preferably, the obtaining joint gaps and contact surfaces of the joint and outputting a contact body structure formed by the contact surfaces of the joint comprises:

[0051] Expanding the joint component bones to be tested outward by a preset thickness to simulate the cartilage thickness of the bone joint surface;

[0052] Partially corroding the joint component bones to be tested on the corresponding bones of the joint surface to form the contact surface / contact volume of the joint, and obtaining a contact body structure model.

[0053] The application further provides a ligament wrapping length quantifying device, comprising:

[0054] The reconstruction module is configured to acquire a knee joint scan image, perform three-dimensional model reconstruction based on the knee joint scan image, perform step-by-step reconstruction on different joint component bones of different ligament wrapping, and output a reconstructed bone joint three-dimensional model.

[0055] The marking module is configured to acquire a joint component bone to be measured and acquire the start and end points of the ligament on the bone according to the anatomical structure.

[0056] The optimization module is configured to perform mesh division to obtain a finite element model according to the reconstructed bone joint three-dimensional model, fill holes to remove noise interference, and output an optimized bone joint three-dimensional model.

[0057] The contact surface construction module is configured to acquire a joint gap and a contact surface of the joint, and output a contact body structure formed by the contact surface of the joint.

[0058] The fitting module is configured to perform optimal fitting of the contact body structure and the joint component bone to be measured, so that the two are combined on the same bone structure, and a ligament bone model to be measured is obtained.

[0059] The calculation and result output module is configured to, when a non-convex structure is generated at different knee joint flexion angles, judge whether the start point is located inside the non-convex structure and whether there is a bone structure block between the start and end points of the ligament, when the start point is located outside the non-convex structure and there is a bone structure block, segmentally calculate the distance between the start and end points, and obtain the shortest distance between the start and end points based on the cross-section method and the optimization algorithm, that is, output the ligament spatial curve length.

[0060] Compared with the prior art, the application has the following beneficial effects:

[0061] The application aims to solve the problem that the prior art cannot accurately measure the ligament spatial curve length when a non-convex structure is generated at a too large knee joint flexion angle by applying three-dimensional CT reconstruction technology to virtually reconstruct the ligament, finding the ligament isometric center around the bone and ligament contact surface, and segmentally calculating, thereby improving the calculation accuracy of the ligament wrapping spatial curve length, and finally realizing fast and accurate calculation of the ligament wrapping spatial curve length.

[0062] The ligament wrapping length quantifying method provided by the application, on the one hand, virtually marks the ligament start and end points and the bone protuberance points on the bone shape reconstruction model, thereby omitting the steps of precise dissection and actual marking, and further realizing research on living bodies.

[0063] In another aspect, the present application takes into account the influence of the bone protrusion on the direction of the ligament, especially when the knee joint flexion angle is too large to form a non-convex structure. By obtaining the center point of the joint contact surface, the ligament is divided into an arc-shaped segment near the bone protrusion and two straight line segments to the starting and ending points of the ligament, and they are measured separately to avoid the interference of the bone protrusion under the non-convex structure, thereby realizing the accurate calculation of the space curve length of the ligament wrapping.

[0064] The ligament plays an important role in joint stability, and its damage can cause many motor function disorders. Generally speaking, for patients with ligament injury, MRI images can clearly show the pathological characteristics of the ligament, but cannot reflect the functional recovery of the ligament after reconstruction. The ligament space curve length method of the present application can be used as a supplement to the functional recovery evaluation method after ligament reconstruction, and the ligament biomechanical properties under postoperative functional activity are evaluated in vivo through the ligament space curve length, and the non-convex structure caused by the bone protrusion when the flexion angle is large is considered, and the space curve length calculation of the ligament wrapping the bone is robustly realized, which is helpful for the clinic to use X-ray images and CT technology to design precise treatment plans for clinical patients, and to develop accurate surgical and rehabilitation plans, and to reduce the occurrence of complications. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 The figure is a quantitative method step diagram for ligament wrapping length in the embodiment of the present application;

[0066] Figure 2 The figure is a cross-sectional view of the medial collateral ligament wrapping in the upright state of the knee joint when there is one bone structure obstruction in the embodiment of the present application;

[0067] Figure 3 The figure is a schematic diagram of the medial collateral ligament wrapping in the upright state of the knee joint when there is one bone structure obstruction in the embodiment of the present application;

[0068] Figure 4 The figure is a cross-sectional view of the anterior cruciate ligament wrapping in the high flexion state of the knee joint when there are two bone structure obstructions in the embodiment of the present application;

[0069] Figure 5 The figure is a schematic diagram of the anterior cruciate ligament wrapping in the high flexion state of the knee joint when there are two bone structure obstructions in the embodiment of the present application;

[0070] Figure 6 The figure is a cross-sectional view of the anterior cruciate ligament wrapping in the hyperextension state of the knee joint when there are three bone structure obstructions in the embodiment of the present application;

[0071] Figure 7 The figure is a schematic diagram of the anterior cruciate ligament wrapping in the hyperextension state of the knee joint when there are three bone structure obstructions in the embodiment of the present application;

[0072] Figure 8 A flowchart of a ligament wrapping length quantification method in an embodiment of the present application. DETAILED DESCRIPTION

[0073] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0074] Embodiment one

[0075] As shown in Figure 1 , 8 , the present application provides a ligament wrapping length quantification method, comprising:

[0076] Step S1, acquiring a knee joint scan image, performing three-dimensional model reconstruction based on the knee joint scan image, step-by-step reconstruction of bone structures of different joints wrapped by different ligaments, and outputting a reconstructed bone joint three-dimensional model;

[0077] Specifically, the step S1 of acquiring a knee joint scan image, performing three-dimensional model reconstruction based on the knee joint scan image, step-by-step reconstruction of bone structures of different joints wrapped by different ligaments, and outputting a reconstructed bone joint three-dimensional model comprises:

[0078] Performing CT tomography or MRI scanning on the knee joint, and outputting a scan image;

[0079] Setting a preset threshold and separating joint bones from soft tissues by threshold segmentation, filtering the soft tissue part interfering with imaging, and retaining joint bones; appropriate threshold setting can reduce the loss of cancellous bone and not retain too much soft tissue to cause joint space blur;

[0080] Performing three-dimensional model reconstruction on the CT tomography image, step-by-step reconstruction and coloring of bone structures of different joints wrapped by different ligaments, and saving as STL format for standby.

[0081] Step S2, obtain the bones of the joint to be measured and obtain the starting and ending points of the ligament on the bone and the bony protuberance points according to the anatomical structure and mark the anchor points, so that the anchor points move with the bone when the position of the knee joint changes; on the bones of the joint to be measured, mark the anchor points of the starting and ending points of the ligament on the bone according to anatomical knowledge. The bony protuberance point refers to the center position of the part protruding on the surface of the bone, which is convenient for marking the starting and ending points of the ligament. When the angle to be measured is obtained, an anchor point is added to the starting and ending points of the ligament, so that the anchor point will move with the bone when the position of the knee joint changes. Export in STL format for backup;

[0082] Step S3, divide the reconstructed bone joint three-dimensional model into a grid to obtain a finite element model, fill the holes to remove noise interference, obtain a solid structure, and output the optimized bone joint three-dimensional model; divide the reconstructed bone joint three-dimensional model into a grid to meet the requirements of specific finite element analysis. In this embodiment, step S3 can also be performed before step S2, that is, the bone joint three-dimensional model is optimized first, and then the starting and ending points of the ligament are marked. This is beneficial to determining the length of the space curve wrapped by the ligament. A three-dimensional finite element model of the ending point of the ligament of the knee joint is established to mark and calculate.

[0083] Step S4, obtain the joint space and the contact surface of the joint, and output the contact body structure formed by the contact surface of the joint;

[0084] Specifically, the step S4 of obtaining the joint space and the contact surface of the joint, and outputting the contact body structure formed by the contact surface of the joint includes:

[0085] The bones of the joint to be measured are expanded outward by a predetermined thickness to simulate the cartilage thickness of the bone joint surface.

[0086] The bones of the joint to be measured are partially corroded on the corresponding bone of the joint surface to form the contact surface / volume of the joint, and a contact body structure model is obtained.

[0087] In this embodiment, the acquisition of the joint contact surface is not limited to the expansion and corrosion operations, and the contact surface can also be obtained by manually marking on the bone joint three-dimensional model.

[0088] Since the CT scan does not show the cartilage structure, in order to obtain the joint space, the bones of the joint to be measured are expanded outward by a certain thickness, which is usually the simulated cartilage thickness of the bone joint surface. At this time, the bone will corrode a part on the corresponding bone of the joint surface, and this part is the contact surface of the joint, that is, a two-dimensional structure. In fact, the corrosion obtains a contact volume, that is, a three-dimensional structure. However, since the thickness of this part is usually very small, it can be approximately regarded as a two-dimensional structure surface, and its geometric center can be regarded as the center point of the contact surface. The obtained model is called a contact body structure. In this embodiment, the position and center point of the contact surface can also be determined according to anatomical knowledge and the angle situation, and then marked to achieve.

[0089] Step S5, the contact body structure is optimally fitted with the joint component bone to be measured, so that the two are combined on the same bone structure, and a ligament bone model to be measured is obtained; in implementation, an artificially determined contact surface center point can also be optimally fitted with the joint component bone to be measured, so that the two are embodied on the same bone.

[0090] Step S6, when a non-convex structure is generated at different flexion angles of the knee joint, it is judged whether the starting point is located inside the non-convex structure and whether there is a bone structure block between the starting and ending points of the ligament; when the starting point is located outside the non-convex structure and there is a bone structure block, the distance between the starting and ending points is calculated in sections, and the shortest distance between the starting and ending points is obtained based on the cross-section method and the optimization algorithm, that is, the length of the ligament spatial curve is output.

[0091] In the embodiment, if all the points on the line connecting any two points in the bone structure are inside the structure, the structure is a convex structure, otherwise it is a non-convex structure. In the embodiment, the bone structure block is the part of the whole bone that blocks the ligament. The present application solves the problem that the existing technology cannot accurately measure the length of the ligament spatial curve when a non-convex structure is generated at a large flexion angle of the knee joint by applying three-dimensional CT reconstruction technology on a living body to virtually reconstruct the ligament, finding the ligament isometric center around the bone-ligament contact surface, and calculating in sections, thereby improving the calculation accuracy of the length of the ligament spatial curve, and finally realizing the fast and accurate calculation of the length of the ligament spatial curve.

[0092] Specifically, in the step S6, when a non-convex structure is generated at different flexion angles of the knee joint, it is judged whether the starting point is located inside the non-convex structure and whether there is a bone structure block between the starting and ending points of the ligament.

[0093] The starting and ending points of the ligament are obtained, and the center point of the contact surface is confirmed;

[0094] The best projection position on the bone surface is obtained after using the cross-section method and optimization processing as the end points of the arc segments;

[0095] The ligament is divided into a first arc segment at the bone protrusion, a first straight segment and a second straight segment to the starting and ending points of the ligament, and the first arc segment, the first straight segment and the second straight segment are quantitatively calculated respectively;

[0096] According to the number of bone structure blocks, the contact surface center point is segmented into one or more wrapping segments with the contact surface center point as the ligament isometric center, and the plurality of wrapping segments at least include a first wrapping segment and a second wrapping segment;

[0097] The contact surface center point of the first wrapping segment is taken as a new starting point of the ligament, the above quantitative steps are repeated to obtain a second arc segment, a third straight segment and a fourth straight segment, and the sum of all arc segments and straight segments is obtained to obtain the length of the ligament spatial curve;

[0098] The first straight segment is formed by connecting the original starting point of the ligament to the starting point of the first arc segment; the second straight segment is formed by connecting the original ending point of the ligament to the ending point of the first arc segment; the starting point, midpoint, and ending point of the arc segment are connected to form an arc segment, the center of the first arc segment corresponds to the center point of the first contact surface, the starting point of the second arc segment is the center point of the first contact surface of the first wrapping segment, the third straight segment is formed by connecting the ending point of the first arc segment to the starting point of the second arc segment, and the fourth straight segment is formed by connecting the original ending point of the ligament to the ending point of the second arc segment. For example, if the starting point A, ending point B, and contact surface center points C / D / E are obtained, there are a total of three wrapping points. The first segment is cut at point C, and the cross-section is made through A / D; the second segment is cut at point D, and the cross-section is made through C / E; the last segment is cut at point E, and the cross-section is made through D / B.

[0099] In this embodiment, in step S6, when a non-convex structure is generated due to different knee flexion angles, it is determined whether the starting point is located inside the non-convex structure and whether there is a bony structure obstructing the ligament's origin and insertion points. When the starting point is located outside the non-convex structure and there is a bony structure obstructing the ligament, the distance between the origin and insertion points is calculated in segments, and the shortest distance between the origin and insertion points is obtained based on the cross-section method and optimization algorithm. That is, the output ligament spatial curve length includes:

[0100] In the first case, when the origin of the ligament is located outside a non-convex structure and there is no bony structure blocking the origin and insertion of the ligament, that is, the number of contact surfaces of the joint is 0, then the straight-line distance between the origin and insertion can be considered as the length of the ligament.

[0101] In the second scenario, when the ligament originates outside a non-convex structure and there is a bony obstruction between the ligament's origin and insertion, refer to... Figures 2-3 As shown, considering the influence of bone protrusions on the ligament orientation, a cross section is made through the origin A and insertion B of the ligament by rotating the bone model of the ligament to be tested. The cross section is perpendicular to the tangent at the center point of the contact surface, and the two cross sections intersect at two points E′ / D′.

[0102] The projection angle of the intersection point on the bone is set as the variable, and the shortest path on the bone surface of the ligament segment is taken as the optimization objective. The optimal projection position E / D of the intersection point on the bone surface is obtained by the optimization algorithm as the endpoint of the arc segment.

[0103] The two ends of the arc and the beginning and ending points of the ligament are respectively used to form the first straight line segment AD, the second straight line segment BE, and the arc segment DCE. The sum of the lengths of the first straight line segment, the second straight line segment, and the arc segment is calculated to obtain the length of the ligament spatial curve.

[0104] In another embodiment, when the origin of the ligament is located outside the convex structure and there is one bone structure between the origin and the end of the ligament, the origin is the cross-sectional origin A, the end is the cross-sectional end B, and the center of the contact surface is the midpoint C of the arc segment to be formed. A cross section is made through the cross-sectional origin and end, intersecting the bone surface at two points D / E, which are the endpoints of the arc segment. The cross section must meet the following two conditions: 1) the projection of the center of the contact surface C on the cross section must be located between the two points D / E to meet the requirement of forming an arc segment; and 2) the rotation angle of the cross section through the origin and end is set as a variable, and the shortest path of the ligament segment on the bone surface is the optimization target. After determining the optimal rotation angle of the cross section, the arc endpoints D / E and the origin A and end B form two straight line segments AD / BE and an arc segment DCE, and the sum is the length of the ligament space curve.

[0105] In the third case, when the origin of the ligament is located outside the convex structure and there are multiple bone structures between the origin and the end of the ligament, multiple wrapping segments are formed, including at least a first wrapping segment and a second wrapping segment. The number of wrapping segments is determined by the number of bone structures, which can be two, three, or any other number, without limitation.

[0106] The first contact surface center point is taken as the new origin of the ligament, and the ligament bone model is rotated. A cross section is made through the origin and end, perpendicular to the contact surface center point, and the two cross sections intersect at two points.

[0107] The projection angle of the cross section intersection point on the bone is set as a variable, and the shortest path of the ligament segment on the bone surface is the optimization target. The best projection position of the intersection point on the bone surface is obtained as the endpoint of the arc segment through the optimization algorithm.

[0108] The arc endpoints and the origin and end of the ligament form a first straight line segment, a second straight line segment, and an arc segment.

[0109] The second contact surface center point of the second wrapping segment is taken as the new origin of the ligament, and the above steps are repeated. Assuming there are N bone structures, N arc segments and N+1 straight line segments are obtained, and the sum of the lengths of the ligament space curve is obtained.

[0110] The following is a specific description of the case where there are two bone structures: Figures 4-5As shown, firstly, the first ligament segment is determined. A cross-section is drawn through the ligament insertion point B and the center point D of the first contact surface, perpendicular to the cross-section at the center point C of the second contact surface. The two cross-sections intersect at two points E′ / F′. The projection angle of the intersection point E′ / F′ on the bone is set as a variable. The shortest path on the bone surface of the ligament segment is used as the optimization objective. The optimal projection position E / F of the intersection point on the bone surface is obtained through an optimization algorithm and serves as the endpoint of the arc segment. The two endpoints of the arc and the center point C of the first contact surface constitute an arc segment ECF. Secondly, the second ligament segment is determined using the same method, resulting in an arc segment HDG. This arc segment HDG is superimposed on the arc segment ECF to obtain the ligament at the two encircling parts. Finally, the endpoints and the start and end points of the arc segment are connected to obtain the straight line segment AH / GF / BE, thus obtaining the entire ligament. Figure 4 The application profile shows the anterior cruciate ligament wrapping. Here, the division of the first and second ligament segments is equivalent to the settings of the first and second wrapping segments mentioned above.

[0111] In another embodiment, when the ligament origin is located outside a non-convex structure and there are multiple bony structures obstructing the ligament's origin and insertion points, forming a wrapping effect, this structure contains an origin A, multiple contact surface center points C / D, and an insertion point B. New cross-sectional origins, the midpoints of the arc segment to be formed, and cross-sectional insertion points are selected sequentially, and the above quantitative steps are repeated: (e.g.) Figures 4-5 As shown, the first ligament segment is first determined. The endpoint is the starting point B of the cross-section, the center point of the first contact surface is the endpoint D of the cross-section, and the center point of the second contact surface is the midpoint C of the arc segment to be formed. A cross-section is drawn through the starting and ending points of the cross-section, intersecting the bone surface at two points E / F as the endpoints of the arc segment. This cross-section must meet the following two conditions: 1) The projection of the center point C of the contact surface onto the cross-section must be located between the two intersecting points E / F to meet the requirements for forming an arc segment; 2) The rotation angle of the cross-section through the starting and ending points is set as a variable, and the shortest path of the ligament segment to the bone surface is used as the optimization objective. After determining the optimal rotation angle of the cross-section, the two endpoints of the arc and the center point C of the first contact surface form an arc segment ECF. Next, the second ligament segment is determined using the same method, resulting in an arc segment HDG. This is superimposed with the arc ECF to obtain the two wrapped portions of the ligament. Finally, the endpoints and starting and ending points of the arc segment are connected to obtain the straight segments AH / GF / BE, thus obtaining the entire ligament.

[0112] Specifically, determining whether the starting point is located inside the non-convex structure when different knee flexion angles create a non-convex structure includes:

[0113] When the origin of a ligament is located inside a non-convex structure, the ligament is obstructed by a bony structure.

[0114] The first contact surface center point is taken as a new starting point to quantitatively operate the ligament space curve length when the ligament starting point is located outside the non-convex structure and there is one bone structure block between the ligament starting and ending points, or the ligament space curve length is quantitatively operated according to the number of remaining contact surface center points when there are multiple bone structure blocks between the ligament starting and ending points.

[0115] The ligament space curve length is obtained by connecting the original starting point and the cross-section proximal point projection point, and summing all the arc segments and straight line segments.

[0116] When the ligament starting point is located inside the non-convex structure, the ligament must exist a bone structure block, as shown in Figures 6-7 The first contact surface center point E is taken as a new starting point to quantitatively operate the one bone structure block and the multiple bone structure blocks, and finally the original starting point and the cross-section proximal point projection point are connected, and the cross-section proximal point is the point closer to the starting point among the two intersection points of the tangent and the cross section. The ligament space curve length is obtained by summing all the arc segments and straight line segments, as shown in Figure 6 The application shows the wrapping situation of the anterior cruciate ligament by using the cross-sectional display. Figure 7

[0117] In another embodiment, when the ligament starting point is located inside the non-convex structure, the first contact surface center point is taken as a new cross-sectional starting point, and the alternative steps in the quantitative operation of the one bone structure block and the quantitative operation of the multiple bone structure blocks are performed according to the number of remaining contact surface center points, and finally the original starting point and the new starting point are connected, and the ligament space curve length is obtained by summing all the arc segments and straight line segments. As shown in Figures 6-7 The first contact surface center point E is taken as a new starting point, and the remaining two contact surface center points C / D, so the quantitative operation of the multiple bone structure blocks is performed, and finally the original starting point and the new starting point AE are connected to obtain the arc segment, Figure 6 The ligament space curve length is obtained by summing all the arc segments and straight line segments.

[0118] Embodiment two

[0119] Based on the same concept, the application also provides a ligament wrapping length quantitative device, comprising:

[0120] The reconstruction module is configured to acquire a knee joint scan image, perform three-dimensional model reconstruction based on the knee joint scan image, perform step-by-step reconstruction on different joint component bone structures of different ligament wrapping, and output a reconstructed bone joint three-dimensional model.

[0121] ​a marking module, configured to obtain bones constituting a joint to be measured, and to obtain starting and ending points of ligaments on the bones and bony protuberance points according to anatomical structures and perform anchor point marking, so that the anchor points move together with the bones when the knee joint position changes;

[0122] an optimization module, configured to perform mesh division according to the reconstructed three-dimensional bone joint model to obtain a finite element model, fill holes to remove noise interference, obtain a solid structure, and output an optimized three-dimensional bone joint model;

[0123] a contact surface construction module, configured to obtain a joint gap and a contact surface of the joint, and output a contact body structure formed by the contact surface of the joint;

[0124] a fitting module, configured to perform optimal fitting of the contact body structure and the bones constituting the joint to be measured, so that the two are combined on the same bone structure, and a ligament bone model to be measured is obtained;

[0125] a calculation and result output module, configured to, when a non-convex structure is generated at different flexion angles of the knee joint, judge whether the starting point is located inside the non-convex structure and whether there is a bony structure block between the starting and ending points of the ligament, when the starting point is located outside the non-convex structure and there is a bony structure block, perform segmented calculation of a distance between the starting and ending points, and obtain a shortest distance between the starting and ending points based on a cross-section method and an optimization algorithm, that is, output a ligament spatial curve length.

[0126] The specific principle contents and implementation methods of the reconstruction module, the marking module, the contact surface construction module, the fitting module, and the calculation and result output module are as described in Embodiment 1, and will not be repeated here.

[0127] By applying a three-dimensional CT reconstruction technology, the ligament is virtually reconstructed, and the ligament isosceles center is found around the bone and ligament contact surface to perform segmented calculation, thereby solving the problem that the prior art cannot accurately quantify the ligament spatial curve length when a non-convex structure is generated at a large flexion angle of the knee joint, improving the calculation accuracy of the ligament wrapping spatial curve length, and finally realizing fast and accurate calculation of the ligament wrapping spatial curve length.

[0128] Finally, in order to apply the above ligament wrapping length quantification method to a length quantification system or device or equipment with related hardware conditions, the application also provides a computer readable storage medium, wherein the computer readable storage medium loads a computer program, and the computer program realizes the functions of the corresponding method embodiments as described above when executed by a computer.

[0129] Similarly, the application also protects a computer readable storage medium loaded with a computer program for implementing the ligament wrapping length quantification method.

[0130] In the embodiments described above, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program. The computer program includes one or more computer programs. When the computer program is loaded on and executed by a computer, all or part of the processes or functions described in the embodiments of the present disclosure are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer program can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer program can be transmitted from one website, computer, server or data center to another website, computer, server or data center through a wired (such as coaxial cable, optical fiber, DDL (Digital Dub DDriber Line, Digital Subscriber Line)) or wireless (such as infrared, wireless, microwave, etc.) manner. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media. The available media can be magnetic media (such as floppy disk, hard disk, magnetic tape), optical media (such as high-density DVD (Digital Video DiDD, Digital Video Disk)), or semiconductor media (such as DDD (olid Dtate DiDk, Solid State Disk)) and the like.

[0131] It should be noted that in the above embodiments, the terms used herein are merely for the purpose of describing specific exemplary embodiments and are not intended to be limiting. As used herein, the singular forms "a," "an," and "the" can be intended to include the plural forms, unless the context clearly indicates otherwise. The terms "comprise," "include" and "have" are inclusive, and thus specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein should not be interpreted as necessarily requiring the described method steps, processes, and operations to be performed in the specific order discussed or illustrated, unless specifically indicated as requiring a set order of execution. It should also be understood that additional or alternative steps can be employed.

[0132] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for quantifying the length of ligament wrapping, characterized in that, include: Acquire knee joint scan images, perform three-dimensional model reconstruction based on the knee joint scan images, and perform step-by-step reconstruction of the bone structures of different joints surrounded by different ligaments and output the reconstructed three-dimensional bone and joint model. Obtain the bone structure of the joint to be tested and determine the origin and insertion points of the ligaments on the bone based on the anatomical structure; The reconstructed 3D model of the bone and joint is meshed to obtain a finite element model. Holes are filled to remove noise interference and the optimized 3D model of the bone and joint is output. Obtain the joint gap and the joint contact surface, and output the contact body structure formed by the contact surface of the joint; The contact structure is best fitted to the bone of the joint to be tested, so that the two are combined on the same bone structure to obtain the bone model of the ligament to be tested. When different knee flexion angles produce non-convex structures, it is determined whether the starting point is located inside the non-convex structure and whether there is a bony structure blocking the ligament's origin and insertion points. When the starting point is located outside the non-convex structure and there is a bony structure blocking the ligament, the distance between the origin and insertion points is calculated in segments, and the shortest distance between the origin and insertion points is obtained based on the section method and optimization algorithm, which is the output of the ligament spatial curve length.

2. The method of claim 1, wherein the step of determining the length of the ligament wrap is performed by a computer program. When different knee flexion angles result in non-convex structures, determining whether the origin is located within the non-convex structure and whether there is bony obstruction between the ligament origin and insertion points includes: Obtain the origin and insertion points of the ligament, and confirm the center point of the contact surface; The optimal projection position on the bone surface was obtained by using the section method and optimization processing to serve as the endpoint of the arc segment; The ligament is divided into a first arc-shaped segment at the bony protrusion and a first straight segment and a second straight segment to the origin and insertion points of the ligament. The first arc-shaped segment, the first straight segment and the second straight segment are quantified respectively. Based on the number of bony structures blocking the ligament, the ligament is divided into one or more wrapping segments with the center point of the contact surface as the center of the ligament length. The multiple wrapping segments include at least a first wrapping segment and a second wrapping segment. Using the center point of the contact surface of the first wrapping segment as the new starting point of the ligament, repeat the above quantitative steps to obtain the second arc segment, the third straight segment, and the fourth straight segment. Summing all the arc segments and straight segments yields the length of the ligament spatial curve. The first straight segment is formed by connecting the original starting point of the ligament to the starting point of the first arc segment; the second straight segment is formed by connecting the original ending point of the ligament to the ending point of the first arc segment; the starting point, midpoint, and ending point of the arc segment are connected to form an arc segment; the center of the first arc segment corresponds to the center point of the first contact surface; the starting point of the second arc segment is the center point of the first contact surface of the first wrapping segment; the third straight segment is formed by connecting the ending point of the first arc segment to the starting point of the second arc segment; and the fourth straight segment is formed by connecting the original ending point of the ligament to the ending point of the second arc segment.

3. The method of claim 1, wherein the step of determining the length of the ligament wrap is performed by a computer program. When different knee flexion angles result in non-convex structures, it is determined whether the starting point is located inside the non-convex structure and whether there is bony obstruction between the ligament's origin and insertion points. When the starting point is located outside the non-convex structure and there is bony obstruction, the distance between the origin and insertion points is calculated in segments, and the shortest distance between the origin and insertion points is obtained based on the section method and optimization algorithm. That is, the output ligament spatial curve length includes: When the origin of the ligament is located outside the non-convex structure and there is a bony structure blocking the origin and insertion of the ligament, rotate the bone model of the ligament to be tested, make a cross section through the origin and insertion of the ligament, perpendicular to the tangent at the center point of the contact surface, and the two cross sections intersect at two points. The projection angle of the intersection point on the bone is set as the variable, and the shortest path on the bone surface of the ligament segment is taken as the optimization objective. The optimal projection position of the intersection point on the bone surface is obtained by the optimization algorithm as the endpoint of the arc segment. The two ends of the arc and the beginning and ending points of the ligament are respectively used to form a first straight line segment, a second straight line segment, and an arc segment. The sum of the lengths of the first straight line segment, the second straight line segment, and the arc segment is calculated to obtain the length of the ligament spatial curve.

4. The method of claim 1, wherein the step of determining the length of the ligament wrap is performed by a computer program. When different knee flexion angles result in non-convex structures, it is determined whether the starting point is located inside the non-convex structure and whether there is bony obstruction between the ligament's origin and insertion points. When the starting point is located outside the non-convex structure and there is bony obstruction, the distance between the origin and insertion points is calculated in segments, and the shortest distance between the origin and insertion points is obtained based on the section method and optimization algorithm. That is, the output ligament spatial curve length includes: When the origin of the ligament is located outside a non-convex structure and there is a bony structure blocking the origin and insertion points of the ligament, a cross section is drawn through the origin and insertion points of the cross section, intersecting the bone surface at two points as the endpoints of the arc segment. This cross section satisfies the following conditions: the projection of the center point of the contact surface onto the cross section is located in the middle of the two intersecting points, so as to meet the requirements of forming an arc segment; the rotation angle of the cross section through the origin and insertion points is set as the variable, and the shortest path of the ligament segment to the bone surface is taken as the optimization objective. After determining the optimal rotation angle of the cross section, the two ends of the arc and the start and end points respectively form the first straight line segment, the first straight line segment and the arc segment. The summation of these segments yields the length of the ligament space curve. The current starting point is the starting point of the cross section, the ending point is the ending point of the cross section, and the center point of the contact surface is the midpoint of the arc segment to be formed.

5. The method of claim 1, wherein the step of determining the length of the ligament wrap is performed by a computer program. When different knee flexion angles result in non-convex structures, it is determined whether the starting point is located inside the non-convex structure and whether there is bony obstruction between the ligament's origin and insertion points. When the starting point is located outside the non-convex structure and there is bony obstruction, the distance between the origin and insertion points is calculated in segments, and the shortest distance between the origin and insertion points is obtained based on the section method and optimization algorithm. That is, the output ligament spatial curve length includes: When the origin of a ligament is located outside a non-convex structure and there are multiple bony structures blocking the origin and insertion points of the ligament, multiple wrapping segments are formed, and the multiple wrapping segments include at least a first wrapping segment and a second wrapping segment. Take the center point of the first contact surface of the first wrapping segment as the new starting point of the ligament, rotate the bone model of the ligament to be tested, make a cross section through the origin and insertion points of the ligament, perpendicular to the tangent at the center point of the contact surface, and the two cross sections intersect at two points. The projection angle of the intersection point on the bone is set as the variable, and the shortest path on the bone surface of the ligament segment is taken as the optimization objective. The optimal projection position of the intersection point on the bone surface is obtained by the optimization algorithm as the endpoint of the arc segment. The two ends of the arc and the origin and end points of the ligament respectively form the first straight line segment, the second straight line segment, and an arc segment; Using the center point of the second contact surface of the second wrapping segment as the new starting point of the ligament, the above steps are repeated cyclically. Assuming there are N bony structures blocking the ligament, a total of N arc segments and N+1 straight segments are obtained. The sum of these segments yields the length of the ligament spatial curve.

6. The method of claim 1, wherein the step of determining the length of the ligament wrap is performed by a computer program. When different knee flexion angles result in non-convex structures, it is determined whether the starting point is located inside the non-convex structure and whether there is bony obstruction between the ligament's origin and insertion points. When the starting point is located outside the non-convex structure and there is bony obstruction, the distance between the origin and insertion points is calculated in segments, and the shortest distance between the origin and insertion points is obtained based on the section method and optimization algorithm. That is, the output ligament spatial curve length includes: When the ligament origin is located outside a non-convex structure and there are multiple bony structures blocking the ligament's origin and insertion points, multiple wrapping segments are formed. These multiple wrapping segments include an origin, multiple contact surface center points, and an insertion point. A new cross-sectional origin, the midpoint of the arc segment to be formed, and the cross-sectional insertion point are selected in sequence. The quantitative steps for the ligament spatial curve length when the ligament origin is located outside a non-convex structure and there are multiple bony structures blocking the ligament's origin and insertion points are repeated.

7. The method of claim 1, wherein the step of determining the length of the ligament wrap is performed by a computer program. When different knee flexion angles result in non-convex structures, determining whether the starting point is located inside the non-convex structure includes: When the origin of a ligament is located inside a non-convex structure, the ligament is obstructed by a bony structure. The first contact surface center point is used as the new starting point for quantitative operation of the ligament spatial curve length when the ligament origin is located outside the non-convex structure and there is a bony structure blocking the ligament origin and insertion point; or the number of remaining contact surface center points is used to select the ligament spatial curve length when there are multiple bony structures blocking the ligament origin and insertion point. Connect the original starting point and the projection point of the near end point of the cross section, and sum all the arc segments and straight line segments to obtain the length of the ligament space curve.

8. The method for quantifying ligament wrapping length as described in claim 1, characterized in that, The process of acquiring knee joint scan images, reconstructing a three-dimensional model based on the knee joint scan images, and reconstructing the bone structures of different joints surrounded by different ligaments in a stepwise manner and outputting the reconstructed three-dimensional bone and joint model includes: Perform CT or MRI scans on the knee joint and output scan images; A preset threshold is set and threshold segmentation is used to separate the joint bones from the soft tissue, filtering out the soft tissue parts that interfere with the imaging and preserving the joint bones; Three-dimensional model reconstruction was performed on the CT scan images. The bone structures of different joints surrounded by different ligaments were reconstructed and colored step by step, and saved as STL format for later use.

9. The method for quantifying ligament wrapping length as described in claim 1, characterized in that, The process of acquiring the joint gap and the joint contact surface, and outputting the contact body structure formed by the joint contact surface includes: The bone of the joint to be tested is expanded outward to a predetermined thickness to simulate the thickness of the cartilage on the articular surface. Partial erosion is performed on the corresponding bone of the joint surface to form the contact surface / contact volume of the joint, thus obtaining the contact body structure model.

10. A device for measuring the length of ligament wrapping, characterized in that, include: The reconstruction module is used to acquire knee joint scan images, perform three-dimensional model reconstruction based on the knee joint scan images, and perform step-by-step reconstruction of the bone structures of different joints surrounded by different ligaments and output the reconstructed three-dimensional bone and joint model. The marking module is used to obtain the constituent bones of the joint under test and to obtain the origin and insertion points of ligaments on the bones based on the anatomical structure. The optimization module is used to perform mesh generation based on the reconstructed 3D bone and joint model to obtain a finite element model, fill holes to remove noise interference, and output the optimized 3D bone and joint model. The contact surface construction module is used to acquire the joint gap and the contact surface of the joint, and output the contact body structure formed by the contact surface of the joint. The fitting module is used to best fit the contact body structure with the bone of the joint to be tested, so that the two are combined on the same bone structure to obtain the ligament bone model to be tested. The calculation and result output module is used to determine whether the starting point is located inside the non-convex structure when different knee flexion angles produce non-convex structures and whether there is a bony structure blocking the ligament's origin and insertion points. When the starting point is located outside the non-convex structure and there is a bony structure blocking it, the distance between the origin and insertion points is calculated in segments, and the shortest distance between the origin and insertion points is obtained based on the section method and optimization algorithm, which is the output of the ligament spatial curve length.

Images