A method and system for calculating the optimal placement orientation of an acetabular cup during total hip arthroplasty

Abstract

The application discloses a kind of calculation method and system of optimal placement orientation of acetabular cup in total hip arthroplasty, belong to surgical instrument field: obtain the CT data of patient and construct three-dimensional model, identify each point in three-dimensional model, establish three-dimensional coordinate system according to pelvis landmark point and femoral head rotation center point, determine femur initial position of movement according to femoral head rotation center point and femoral landmark point.According to femur form and pre-set hip joint range of motion, the space femoral neck range of motion is drawn.Based on the space femoral neck range of motion, the centroid of its surface is calculated, and the ray is formed by extending from the femoral head rotation center point to the centroid direction, and the orientation of the ray in the three-dimensional coordinate is used as the optimal placement orientation of the acetabular cup.The personalized femur form and joint range of motion of the patient are considered, and the optimal acetabular orientation is given according to different prostheses, which provides a clear surgical target and guidance for the surgeon, thereby reducing the risk of dislocation after hip arthroplasty and greatly improving the reliability of acetabular cup placement.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of surgical instruments, and particularly relates to a method and system for calculating the optimal placement direction of an acetabular cup in total hip arthroplasty. BACKGROUND

[0002] Total hip arthroplasty (THA) is considered to be one of the most effective and safest surgeries for treating hip diseases, relieving pain and restoring function of patients. Globally, more than 1 million hip arthroplasties are performed each year to treat severe hip osteoarthritis, femoral head necrosis, congenital hip dysplasia and other hip diseases. The placement direction of the acetabular prosthesis has long been considered an important factor affecting the success rate of THA. Poor placement of the acetabular prosthesis can increase prosthesis wear, edge load and impingement rate, which can lead to a series of complications such as osteolysis and dislocation. As for artificial joint dislocation, the Lewinnek and combined anteversion angle concepts were initially recognized, but after a large number of clinical practices, they were found to be unreliable. Even if the placement position of the acetabular prosthesis is within the above-mentioned safe zone, a large number of dislocation cases still occur. With the increasing power of computer simulation, new concepts such as the combined sagittal plane index and functional safety zone have been proposed, but these methods have not been widely recognized. In the face of such clinical difficulties and needs, the present application combines the individualized pelvic and femoral morphology of the patient and the joint range of motion required in daily life to propose the theory that there is an optimal placement direction for the acetabular cup, and to develop a method for calculating the optimal placement direction of the acetabular cup based on the preoperative CT and digital model of the daily joint activity of the patient. SUMMARY

[0003] The technical purpose of the present application is to provide a method and system for calculating the optimal placement direction of an acetabular cup in total hip arthroplasty, so as to achieve optimal placement of the acetabular cup in total hip arthroplasty.

[0004] To solve the above problems, the technical scheme of the present application is as follows:

[0005] A method for calculating the optimal placement direction of an acetabular cup in total hip arthroplasty, comprising the following steps:

[0006] Obtain CT data of a patient and construct a three-dimensional model, identify pelvic landmark points, femoral landmark points, femoral head center points and femoral head rotation center points in the three-dimensional model, establish a three-dimensional coordinate system according to the pelvic landmark points and the femoral head rotation center points, and determine the initial position of femoral movement according to the femoral head rotation center points and the femoral landmark points;

[0007] According to the femoral anteversion angle, the femoral neck shaft angle and the preset hip joint range of motion, the spatial femoral neck range of motion is drawn, specifically by drawing the motion surface of the intersection of the femoral neck and the femoral shaft in the three-dimensional model;

[0008] The centroid of the curved surface is calculated based on the range of motion of the femoral neck in space. A ray is formed by extending from the center of rotation of the femoral head towards the centroid. The orientation of the ray in three-dimensional coordinates is used as the optimal orientation for the placement of the acetabular cup. The abduction angle and anteversion angle of the acetabulum are then output as references for the placement of the acetabular cup.

[0009] In the step of constructing the three-dimensional model, the pelvic landmarks include the left anterior superior iliac spine, the right anterior superior iliac spine, and the midpoint of the pubic symphysis, located on both sides of the pelvis; the femoral landmarks include the lateral femoral condyle and the medial femoral condyle.

[0010] A three-dimensional coordinate system is established using the plane defined by the left anterior superior iliac spine, the right anterior superior iliac spine, and the midpoint of the pubic symphysis as the coronal plane;

[0011] The midpoint of the line connecting the lateral and medial femoral condyles is taken as the center of the knee joint. The center of the knee joint is connected to the center of rotation of the femoral head to form the femoral line. When the femoral line is perpendicular to the cross-section, the position of the femur is the initial position of femoral movement.

[0012] The specific steps for drawing the range of motion of the femoral neck in space are as follows:

[0013] Define the joint movements of the femur, and construct rotation matrices for the flexion-extension, abduction-adduction, and internal-external rotation movements of the femur. , and ;

[0014] The constructed rotation matrices are combined in order to obtain the final rotation matrix:

[0015]

[0016] The spatial position of the femoral neck is calculated based on the final rotation matrix and the center point of the femoral head:

[0017]

[0018] in, These are the coordinates of the center point of the femoral head when the femur is in its initial position. ;

[0019] By changing the anteversion angle and neck-shaft angle of the femur, and combining the rotation matrix, the coordinates of the acetabular centerline at different angles are calculated.

[0020] Based on the above calculation results, the three-dimensional range of motion of the femoral neck under different femoral anteversion angles and neck-shaft angles was plotted to obtain a three-dimensional point cloud map.

[0021] Specifically, the joint movements of the femur are defined as follows:

[0022] Flexion-extension movement of the femur is achieved by rotation around the global x-axis, satisfying the following formula:

[0023]

[0024] wherein, is the flexion-extension angle of the femur;

[0025] Abduction-adduction movement of the femur is achieved by rotation around the global y-axis, satisfying the following formula:

[0026]

[0027] wherein, is the abduction-adduction angle of the femur;

[0028] Internal-external rotation movement of the femur is achieved by rotation around the global z-axis, satisfying the following formula:

[0029]

[0030] wherein, is the internal-external rotation angle of the femur.

[0031] wherein, the calculation of the center of mass is specifically:

[0032] The coordinates of all points of the femoral neck in the three-dimensional point cloud diagram are represented as (X, Y, Z), and the mean values of the X, Y and Z coordinates of all points are calculated, and the calculation formula is:

[0033]

[0034] wherein, is the coordinate corresponding to the point is the mass corresponding to the point is the kth coordinate in the three-dimensional point cloud diagram.

[0035] wherein, the acetabular abduction angle is the included angle between the ray projection to the coronal plane and the sagittal plane after the coronal plane; the acetabular anteversion angle is the included angle between the ray projection to the transverse plane and the coronal plane after the transverse plane.

[0036] A calculation system for the optimal placement direction of an acetabular cup in total hip arthroplasty, comprising:

[0037] An input module configured to input CT data of a patient and parameters of a prosthesis to be implanted;

[0038] ​​​The three-dimensional simulation module is configured to construct a three-dimensional model according to input CT data, identify a pelvis landmark point, a femur landmark point, a femur ball head center point and a femur head rotation center point in the three-dimensional model, establish a three-dimensional coordinate system according to the pelvis landmark point and the femur head rotation center point, and determine an initial position of femur movement according to the femur head rotation center point and the femur landmark point; and draw a spatial femur neck movement range according to a femur anteversion angle, a femur neck-shaft angle and a preset hip joint movement range, specifically by drawing a movement surface of an intersection of a femur neck and a femur shaft of the femur in the three-dimensional model.

[0039] The calculation module is configured to calculate a centroid of the surface of the spatial femur neck movement range, extend a ray from the femur head rotation center point to the centroid, and take an orientation of the ray in the three-dimensional coordinate system as the optimal placement orientation of the acetabular cup.

[0040] The output module is configured to display and output a hip joint abduction angle and a hip joint anteversion angle in the optimal placement orientation of the acetabular cup as a reference.

[0041] Preferably, the three-dimensional simulation module is further configured to establish the three-dimensional coordinate system by taking a plane defined by a left anterior superior iliac spine point, a right anterior superior iliac spine point and a pubic symphysis point of the pelvis landmark point as a coronal plane.

[0042] The three-dimensional simulation module is further configured to connect the femur head rotation center point and a knee joint center, which is a midpoint of a line connecting a lateral femoral condyle point and a medial femoral condyle point of the femur landmark point, to form a femur line, and when the femur line is perpendicular to a transverse plane, the position of the femur is the initial position of femur movement.

[0043] Preferably, the three-dimensional simulation module is further configured to draw the spatial femur neck movement range,

[0044] define joint movement of the femur, and construct rotation matrices for flexion-extension movement, abduction-adduction movement and internal-external rotation movement of the femur, 、 and respectively.

[0045] combine the constructed rotation matrices in order to obtain a final rotation matrix:

[0046]

[0047] calculate a spatial position of the femur neck based on the final rotation matrix and the femur ball head center point:

[0048]

[0049] wherein, is a position coordinate of the femur ball head center point when the femur is in the initial position, .

[0050] By changing the anteversion angle and neck-stem angle of the femur, combined with the rotation matrix, the calculation results of the centerline coordinates of the acetabulum under different angles are obtained.

[0051] According to the above calculation results, the three-dimensional motion range of the femoral neck under different femoral anteversion angles and neck-stem angles is drawn, and a three-dimensional point cloud diagram is obtained.

[0052] Preferably, the three-dimensional simulation module is further configured to define the joint motion of the femur,

[0053] The flexion-extension motion of the femur is realized by rotation around the global x-axis, and the following formula is satisfied:

[0054]

[0055] Wherein, is the flexion-extension angle of the femur;

[0056] The abduction-adduction motion of the femur is realized by rotation around the global y-axis, and the following formula is satisfied:

[0057]

[0058] Wherein, is the abduction-adduction angle of the femur;

[0059] The internal-external rotation motion of the femur is realized by rotation around the global z-axis, and the following formula is satisfied:

[0060]

[0061] Wherein, is the internal-external rotation angle of the femur.

[0062] Preferably, the calculation module is further configured to calculate the center of mass,

[0063] The coordinates of all points of the femoral neck in the three-dimensional point cloud diagram are represented as (X, Y, Z), and the mean values of the X, Y and Z coordinates of all points are calculated, and the calculation formula is:

[0064]

[0065] Wherein, is the coordinate corresponding to the point is the mass corresponding to the point is the first coordinate in the three-dimensional point cloud diagram.

[0066] The present application has the following advantages and positive effects compared with the prior art due to the use of the above technical scheme: ​​​

[0067] The present application considers the personalized femoral morphology and joint range of motion of the patient by inputting the CT parameters of the patient and the parameters of the prosthesis to be implanted, and gives the optimal acetabular orientation according to different prostheses, gives the surgeon a clear surgical goal and guidance, thereby reducing the risk of dislocation after hip arthroplasty and greatly improving the reliability of the placement of the acetabular cup. BRIEF DESCRIPTION OF DRAWINGS

[0068] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included only to illustrate preferred embodiments and are not intended to limit the present application.

[0069] Figure 1 A flowchart of a method for calculating the optimal placement orientation of the acetabular cup in total hip arthroplasty according to the present application;

[0070] Figure 2 A schematic diagram of the positions of the landmark points on the pelvis according to the present application;

[0071] Figure 3 A schematic diagram of the positions of the landmark points on the femur and the center point of the femoral head according to the present application;

[0072] Figure 4 A schematic diagram of the position of the center point of the acetabulum according to the present application;

[0073] Figure 5 A schematic diagram of the femoral anteversion angle according to the present application;

[0074] Figure 6 A schematic diagram of the femoral neck-stem angle according to the present application;

[0075] Figure 7 A schematic diagram of the three-dimensional cloud point diagram formed by the femoral neck under the three-dimensional range of motion according to the present application;

[0076] Figure 8 A schematic diagram of the acetabular abduction angle and the acetabular anteversion angle output by the present application. DETAILED DESCRIPTION

[0077] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, specific embodiments of the present application will be described below with reference to the accompanying drawings. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings and other embodiments according to these drawings without creative labor.

[0078] For simplicity and concision of the drawings, only parts related to the present application are shown in the drawings, which do not represent the actual structure of the product. In addition, for simplicity and ease of understanding of the drawings, in some drawings, only one of the parts with the same structure or function is shown schematically, or only one of them is marked. In this text, "one" not only means "only one", but also means "more than one".

[0079] The application will be further described in detail below with reference to the drawings and specific embodiments. The advantages and features of the present application will be clearer according to the following description and claims.

[0080] Embodiment 1

[0081] Referring to Figures 1 to 8 , the embodiment provides a method for calculating the optimal placement direction of the acetabular cup in total hip arthroplasty, which mainly comprises the following steps:

[0082] First, step S1: CT data of the patient needs to be obtained and a three-dimensional model needs to be constructed. The imported CT data requires from the anterior superior iliac spine to the tibial tuberosity, including two joints of the hip and knee, which can be used to determine the femoral anteversion angle. By identifying the pelvic landmark points, femoral landmark points, femoral head center points and femoral head rotation center points (i.e. Figure 4 the center point of the acetabulum) in the three-dimensional model, as shown in Figure 2 , the pelvic landmark points include the left anterior superior iliac spine point, the right anterior superior iliac spine point and the pubic symphysis midpoint on both sides of the pelvis; as shown in Figure 3 , the femoral landmark points include the lateral femoral condyle point and the medial femoral condyle point. A three-dimensional coordinate system is established with the coronal plane of the pelvis as the coronal plane, and the plane of the anterior pelvis is determined by the left anterior superior iliac spine point, the right anterior superior iliac spine point and the pubic symphysis midpoint. Further, the three-dimensional coordinate system selects the femoral head rotation center point as the origin. Preferably, the midpoint of the line connecting the lateral femoral condyle point and the medial femoral condyle point is the center of the knee joint, and the knee joint center is connected with the femoral head rotation center point to form a femoral connecting line. When the femoral connecting line is perpendicular to the transverse plane, the position of the femur is the initial position of the femoral movement, with 0° of the precursor, 0° of the adduction and 0° of the internal rotation.

[0083] Then go to the next step, step S2: according to the femoral morphology and the preset hip joint range of motion, draw the spatial femoral neck range of motion. Among them, the femoral morphology includes the femoral anteversion angle and the femoral neck angle, as shown in Figure 5 and Figure 6The femoral neck-shaft angle is specific to the femoral prosthesis model selected. The range of motion of the femur relative to the pelvis can be: extension (-) - flexion (+): -30° to +110°; abduction (-) - adduction (+): -35° to +30°; external rotation (-) - internal rotation (+): -45° to +45°, which are preferred ranges, but are not limited thereto. Depending on the femoral anteversion angle and the femoral neck-shaft angle, a motion surface of the intersection of the femoral neck and the femoral shaft in the three-dimensional model is plotted.

[0084] The specific steps for plotting the spatial femoral neck range of motion are as follows:

[0085] The joint motion of the femur is defined by three basic rotational motions, in sequence, flexion-extension motion, abduction-adduction motion, and internal-external rotation motion.

[0086] For the flexion-extension motion, the flexion-extension motion of the femur is achieved by rotation around the global x-axis (θx) , which satisfies the following formula:

[0087]

[0088] wherein, is the flexion-extension angle of the femur, ranging from -30° to +110°.

[0089] For the abduction-adduction motion, the abduction-adduction motion of the femur is achieved by rotation around the global y-axis (θy) , which satisfies the following formula:

[0090]

[0091] wherein, is the abduction-adduction angle of the femur, ranging from -35° to +30°;

[0092] For the internal-external rotation motion, the internal-external rotation motion of the femur is achieved by rotation around the global z-axis (θz) , which satisfies the following formula:

[0093]

[0094] wherein, is the internal-external rotation angle of the femur, ranging from -45° to +45°.

[0095] Then, since the motion of the femur is obtained by sequentially combining three rotation matrices, in sequence, flexion-extension motion, abduction-adduction motion, and internal-external rotation motion, the final rotation matrix is obtained as follows:

[0096]

[0097] Further, considering the influence of femoral anteversion angle and femoral abduction angle on the acetabular centerline, the position of the femoral neck needs to be calculated from the original point (the center point of the femoral head) to a new position. At this time, the final rotation matrix can be used to obtain the spatial position of the femoral neck:

[0098]

[0099] wherein, is the coordinate of the center point of the femoral head when the femur is in the initial position, .

[0100] Then, by changing the anteversion angle and abduction angle of the femur and combining the rotation matrix, the calculation results of the acetabular centerline coordinates under different angles can be obtained. Each set of anteversion angle and abduction angle will generate a new acetabular centerline coordinate.

[0101] According to the above calculation results, the three-dimensional motion range of the femoral neck under different femoral anteversion angles and abduction angles is drawn, and finally a three-dimensional point cloud graph is output, as shown in Figure 7 , which shows the change of the position of the femoral neck in space.

[0102] Finally, step S3: referring to Figure 8 , the centroid of the surface of the femoral neck is calculated based on the spatial motion range of the femoral neck. A ray is formed from the center point of the femoral head to the centroid, and the orientation of the ray in the three-dimensional coordinate is taken as the best placement direction of the acetabular cup. Then, the abduction angle of the acetabular cup and the anteversion angle of the acetabular cup are output as the reference for placing the acetabular cup, providing clear surgical targets and guidance for medical personnel. The abduction angle of the acetabular cup is the included angle between the projection of the ray to the coronal plane and the sagittal plane, and the anteversion angle of the acetabular cup is the included angle between the projection of the ray to the transverse plane and the coronal plane.

[0103] wherein, the centroid is the geometric center of an object, which is the weighted average of the positions of all mass elements of the object in mathematics. For an object distributed in three-dimensional space, the coordinates of the centroid are . Therefore, all point coordinates of the femoral neck in the three-dimensional point cloud graph are represented by (X, Y, Z), and the average value of the X, Y, Z coordinates of all points is the centroid, and the calculation formula is:

[0104]

[0105] wherein, is the coordinate corresponding to point , is the mass corresponding to point , is the mass corresponding to point The system uses a set of coordinates, and in this embodiment, it can be assumed that the mass of each point is equal, which can be simplified to 1, and the mass does not need to be considered. Therefore, the calculation of the centroid is actually the average of the coordinates of all points.

[0106] Example 2

[0107] This embodiment also provides a calculation system for the optimal placement orientation of the acetabular cup during total hip arthroplasty, which includes an input module, a three-dimensional simulation module, a calculation module, and an output module.

[0108] The input module is used to input the patient's CT data and the femoral parameters of the prosthesis to be implanted.

[0109] The 3D simulation module is used to construct a 3D model based on the input CT data, identify pelvic landmarks, femoral landmarks, the center point of the femoral head, and the center point of femoral head rotation in the 3D model, establish a 3D coordinate system based on the pelvic landmarks and the center point of femoral head rotation, determine the initial position of femoral movement based on the center point of femoral head rotation and femoral landmarks, and draw the spatial range of motion of the femoral neck based on the femoral anteversion angle, the femoral neck-shaft angle, and the preset range of motion of the hip joint. Specifically, it is drawn using the motion surface of the intersection of the femoral neck and the femoral shaft in the 3D model.

[0110] Preferably, the three-dimensional simulation module further establishes a three-dimensional coordinate system using the plane defined by the left anterior superior iliac spine, the right anterior superior iliac spine, and the midpoint of the pubic symphysis as the coronal plane.

[0111] The midpoint of the line connecting the lateral and medial femoral condyles, which are femoral landmarks, is taken as the center of the knee joint. The center of the knee joint is connected to the center of rotation of the femoral head to form the femoral line. When the femoral line is perpendicular to the cross-section, the position of the femur is the initial position of femoral movement.

[0112] Preferably, the 3D simulation module is used to map the range of motion of the femoral neck in space, specifically:

[0113] Define the joint movements of the femur, and construct rotation matrices for the flexion-extension, abduction-adduction, and internal-external rotation movements of the femur. , and ;

[0114] The constructed rotation matrices are combined in order to obtain the final rotation matrix:

[0115]

[0116] The spatial position of the femoral neck is calculated based on the final rotation matrix and the center point of the femoral head:

[0117]

[0118] wherein, is the position coordinate of the center point of the femoral head when the femur is in the initial position, ;

[0119] By changing the femoral anteversion angle and the femoral neck-shaft angle, combined with the rotation matrix, the calculation results of the center line coordinates of the acetabulum under different angles are obtained;

[0120] According to the above calculation results, the three-dimensional motion range of the femoral neck under different femoral anteversion angles and femoral neck-shaft angles is drawn, and a three-dimensional point cloud diagram is obtained.

[0121] Preferably, the three-dimensional simulation module is further used to define the joint motion of the femur, and the flexion-extension motion of the femur is realized by rotation around the global x-axis, satisfying the following formula:

[0122]

[0123] wherein, is the flexion-extension angle of the femur;

[0124] The abduction-adduction motion of the femur is realized by rotation around the global y-axis, satisfying the following formula:

[0125]

[0126] wherein, is the abduction-adduction angle of the femur;

[0127] The internal-external rotation motion of the femur is realized by rotation around the global z-axis, satisfying the following formula:

[0128]

[0129] wherein, is the internal-external rotation angle of the femur.

[0130] The calculation module is used to calculate the centroid of the surface of the femoral neck based on the spatial femoral neck activity range, and a ray is formed by extending from the rotation center point of the femoral head to the centroid, and the orientation of the ray in the three-dimensional coordinates is taken as the best placement direction of the acetabular cup.

[0131] Preferably, the calculation module specifically calculates the centroid as:

[0132] All point coordinates of the femoral neck in the three-dimensional point cloud diagram are represented as (X, Y, Z), and the mean values of the X, Y, and Z coordinates of all points are calculated, and the calculation formula is:

[0133]

[0134] wherein, is the point corresponding coordinates, for the point corresponding mass, for the third coordinate in the three-dimensional point cloud.

[0135] The output module is used for displaying the output acetabular abduction angle and acetabular anteversion angle in the best placement direction of the acetabular cup as a reference, so as to provide clear operation targets and guidance for medical staff.

[0136] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the above-described embodiments. Even if various changes are made to the present application, if the changes belong to the scope of the claims of the present application and equivalent technologies thereof, they still fall within the protection scope of the present application.

Claims

1. A method of calculating the optimal placement orientation of an acetabular cup during total hip arthroplasty, characterized in that, The method comprises the following steps: Obtaining CT data of a patient and constructing a three-dimensional model, identifying a pelvis landmark point, a femur landmark point, a femur ball head center point and a femur head rotation center point in the three-dimensional model, establishing a three-dimensional coordinate system according to the pelvis landmark point and the femur head rotation center point, and determining an initial position of femur movement according to the femur head rotation center point and the femur landmark point; According to the femur anteversion angle, the femur neck-shaft angle and a preset hip joint activity range, a spatial femur neck activity range is drawn, specifically by drawing a motion surface of the intersection point of the femur neck and the femur shaft of the femur in the three-dimensional model; Based on the spatial femur neck activity range, a centroid of the surface thereof is calculated, a ray is extended from the femur head rotation center point to the centroid, and the direction of the ray in the three-dimensional coordinate system is taken as the optimal placement direction of the acetabular cup, and then the acetabular abduction angle and the acetabular anteversion angle are output as the acetabular cup placement reference; The specific steps of drawing the spatial femur neck activity range are as follows: Defining the joint motion of the femur, the flexion-extension motion, abduction-adduction motion and internal-external rotation motion of the femur are constructed respectively by rotation matrix , and ; The constructed rotation matrices are combined in sequence to obtain a final rotation matrix: Based on the final rotation matrix and the femur ball head center point, the spatial position of the femur neck is calculated: wherein, is a position coordinate of the center point of the femoral ball head when the femur is in the initial position, ; By changing the anteversion angle and the neck-shaft angle of the femur, the calculation results of the acetabular center line coordinates under different angles are obtained in combination with the rotation matrix; According to the calculation results, the three-dimensional motion range of the femur neck under different femur anteversion angles and neck-shaft angles is drawn to obtain a three-dimensional point cloud diagram.

2. The method for calculating the optimal placement orientation of an acetabular cup during total hip arthroplasty according to claim 1, wherein, In the step of constructing the three-dimensional model, the pelvis landmark points include left anterior superior iliac spine points, right anterior superior iliac spine points and pubic symphysis points on both sides of the pelvis, and the femur landmark points include femur lateral condyle points and femur medial condyle points; The three-dimensional coordinate system is established with the plane determined by the left anterior superior iliac spine point, the right anterior superior iliac spine point and the pubic symphysis point as the coronal plane; The knee joint center is the midpoint of the line connecting the femur lateral condyle point and the femur medial condyle point, and the knee joint center is connected with the femur head rotation center point to form a femur connecting line, and when the femur connecting line is perpendicular to the transverse plane, the position of the femur is the initial position of the femur movement.

3. The method for calculating the optimal placement orientation of an acetabular cup during total hip arthroplasty according to claim 1, wherein, The joint movement of the femur is defined as follows: The flexion-extension movement of the femur is realized by rotation around the global x-axis, and the following formula is satisfied: wherein, is the flexion angle of the femur; The abduction-adduction movement of the femur is realized by rotation around the global y-axis, and the following formula is satisfied: wherein, is the abduction-adduction angle of the femur; The internal-external rotation movement of the femur is realized by rotation around the global z-axis, and the following formula is satisfied: wherein, is the angle of internal and external rotation of the femur.

4. The method for calculating the optimal placement orientation of an acetabular cup during total hip arthroplasty of claim 1, wherein, The calculation of the centroid is as follows: The coordinates of all points of the femur neck in the three-dimensional point cloud diagram are represented as (X, Y, Z), and the mean values of the X, Y and Z coordinates of all points are calculated, and the calculation formula is as follows: wherein, is a point corresponding to the coordinate, is a point corresponding to the mass, is the coordinate of the i-th point in the three-dimensional point cloud map. th point in the three-dimensional point cloud map.

5. The method of calculating the optimal placement orientation of an acetabular cup in a total hip arthroplasty according to claim 1, wherein, The acetabular abduction angle is the included angle between the ray and the sagittal plane after the ray is projected onto the coronal plane, and the acetabular anteversion angle is the included angle between the ray and the coronal plane after the ray is projected onto the transverse plane.

6. A system for calculating the optimal placement orientation of an acetabular cup during total hip arthroplasty, comprising: The method comprises the following steps: The input module is configured to input CT data of a patient and parameters of a prosthesis to be implanted. The three-dimensional simulation module is configured to construct a three-dimensional model according to input CT data, identify a pelvis landmark point, a femur landmark point, a femur ball head center point and a femur head rotation center point in the three-dimensional model, establish a three-dimensional coordinate system according to the pelvis landmark point and the femur head rotation center point, and determine an initial position of femur movement according to the femur head rotation center point and the femur landmark point; draw a spatial femur neck movement range according to a femur anteversion angle, a femur neck-shaft angle and a preset hip joint movement range, and specifically draw a movement surface of an intersection point of a femur neck and a femur shaft in the three-dimensional model; The calculation module is configured to calculate a centroid of a surface of the spatial femur neck movement range, extend a ray from the femur head rotation center point to the centroid, and take an orientation of the ray in the three-dimensional coordinate system as an optimal placing orientation of an acetabular cup; The output module is configured to display and output a reference of an acetabular abduction angle and an acetabular anteversion angle in the optimal placing orientation of the acetabular cup; The three-dimensional simulation module is further configured to draw the spatial femur neck movement range, Defining the joint motion of the femur, the flexion-extension motion, abduction-adduction motion and internal-external rotation motion of the femur are constructed respectively by rotation matrix , and ; combine the constructed rotation matrices in sequence to obtain a final rotation matrix: calculate a spatial position of the femur neck based on the final rotation matrix and the femur ball head center point: wherein, is a position coordinate of the center point of the femoral ball head when the femur is in the initial position, ; obtain calculation results of acetabular center line coordinates in different angles by changing the anteversion angle and the neck-shaft angle of the femur and combining the rotation matrix; draw a three-dimensional movement range of the femur neck in different anteversion angles and neck-shaft angles of the femur based on the calculation results to obtain a three-dimensional point cloud diagram.

7. The system for intraoperatively computing an optimal orientation of a femoral cup of a total hip arthroplasty of claim 6, wherein, The three-dimensional simulation module is further configured to take a plane determined by a left anterior superior iliac spine point, a right anterior superior iliac spine point and a pubic symphysis point of the pelvis landmark point as a coronal plane, and establish the three-dimensional coordinate system; take a midpoint of a line connecting a lateral condyle point of the femur landmark point and a medial condyle point of the femur as a knee joint center, connect the knee joint center and the femur head rotation center point to form a femur connecting line, and when the femur connecting line is perpendicular to a transverse plane, the position of the femur is the initial position of femur movement.

8. The system for intraoperatively computing an optimal orientation of a femoral cup of a total hip arthroplasty of claim 6, wherein, The three-dimensional simulation module is further configured to define joint movement of the femur, achieve flexion-extension movement of the femur by rotation around a global x-axis, and satisfy the following formula: wherein, is the flexion angle of the femur; achieve abduction-adduction movement of the femur by rotation around a global y-axis, and satisfy the following formula: wherein, is the abduction-adduction angle of the femur; achieve internal-external rotation movement of the femur by rotation around a global z-axis, and satisfy the following formula: wherein, is the angle of internal and external rotation of the femur.

9. The computed system for intraoperatively optimal cup orientation in total hip arthroplasty of claim 6, wherein, The calculation module is further configured to calculate the centroid, represent all point coordinates of the femur neck in the three-dimensional point cloud diagram as (X, Y, Z), and calculate mean values of X, Y and Z coordinates of all points, and a calculation formula is as follows: wherein, is a point corresponding to a coordinate, is a point corresponding to a mass, is the coordinate of the i-th point in the three-dimensional point cloud map. th point in the three-dimensional point cloud map.

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