Elbow replacement surgery preoperative planning system

Abstract

The present invention provides a preoperative planning system for elbow replacement surgery, the system comprising: a model building unit, for building an elbow joint model based on elbow joint CT data; a coordinate building unit, for building an elbow joint coordinate system based on the elbow joint model; and a preoperative planning unit, for performing preoperative planning for elbow replacement surgery based on the elbow joint coordinate system. The present invention builds an elbow joint model based on elbow joint CT data, thereby building an elbow joint coordinate system based on the elbow joint model, and then can quickly and accurately perform preoperative planning for elbow replacement surgery based on the elbow joint coordinate system without relying on the doctor's clinical experience.

Description

Technical Field

[0001] The present invention relates to the field of computer technology, and in particular to a preoperative planning system for elbow replacement surgery. Background Art

[0002] Total elbow replacement is a common orthopedic surgery, which is a kind of orthopedic surgery that replaces the diseased joint of the human body with an artificial joint prosthesis. Before the traditional total elbow replacement surgery, the doctor needs to determine the bone axis of the elbow joint, the osteotomy area and osteotomy path of the elbow joint based on clinical experience. It is highly dependent on the doctor's clinical experience, and the efficiency and accuracy of preoperative planning are low. Summary of the invention

[0003] The present invention provides a preoperative planning system for elbow replacement surgery, which is used to solve the defects of low efficiency and accuracy of preoperative planning for elbow replacement surgery in the prior art.

[0004] The present invention provides a preoperative planning system for elbow replacement surgery, comprising:

[0005] A model building unit, used for building an elbow joint model based on elbow joint CT data;

[0006] A coordinate establishing unit, used for establishing an elbow joint coordinate system based on the elbow joint model;

[0007] The preoperative planning unit is used to perform preoperative planning of elbow replacement surgery based on the elbow joint coordinate system.

[0008] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the elbow joint coordinate system is established based on the elbow joint model, including:

[0009] Converting the elbow joint model into point cloud data;

[0010] Based on the point cloud data, determining the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus; the line connecting the medial and lateral condyles of the humerus refers to the line connecting the medial epicondyle of the humerus and the lateral epicondyle of the humerus;

[0011] The elbow joint coordinate system is established based on the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus.

[0012] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the anatomical axis of the humeral shaft is determined based on the following steps:

[0013] Slicing the point cloud data corresponding to the humeral shaft to obtain a plurality of humeral shaft slices;

[0014] The centroid coordinates of each humeral shaft slice are extracted, and a straight line fitting is performed on the centroid coordinates of each humeral shaft slice to obtain the anatomical axis of the humeral shaft.

[0015] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the elbow joint coordinate system is established based on the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus, including:

[0016] Determine a first vector based on the anatomical axis of the humeral shaft and a line connecting the medial and lateral condyles of the humerus;

[0017] Determining a second vector based on the first vector and the anatomical axis of the humeral shaft;

[0018] The elbow joint coordinate system is established based on the anatomical axis of the humeral shaft, the first vector and the second vector; the origin of the elbow joint coordinate system is the intersection of the curved surface where the olecranon fossa of the humerus is located and the anatomical axis of the humeral shaft.

[0019] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the algorithms corresponding to the straight line fitting are a random sampling consensus algorithm and an overall least squares algorithm.

[0020] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the preoperative planning for elbow replacement surgery is performed based on the elbow joint coordinate system, comprising:

[0021] Planning the osteotomy area based on the elbow joint coordinate system and the humeral osteotomy plate parameters;

[0022] The needle insertion direction and grinding range are planned based on the anatomical axis of the ulna and the parameters of the ulnar prosthesis.

[0023] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the humeral osteotomy plate parameters include the distance between two parallel planes of the humeral osteotomy plate and the angle between two other intersecting planes of the humeral osteotomy plate;

[0024] The step of planning the osteotomy area based on the elbow joint coordinate system and the humeral osteotomy plate parameters includes:

[0025] Based on the elbow joint coordinate system and the distance between the two parallel planes of the humeral osteotomy plate, planning the positions of two mutually parallel cutting planes in the osteotomy area;

[0026] Based on the position of the lowest point of the olecranon fossa, the elbow joint coordinate system and the angle between the other two intersecting planes of the humeral osteotomy plate, the positions of the two inclined planes of the osteotomy area are determined.

[0027] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the needle insertion direction and grinding range are planned based on the anatomical axis of the ulna and the parameters of the ulna prosthesis, including:

[0028] The needle insertion direction is planned based on the anatomical axis of the ulna and the position of the base of the coracoid process;

[0029] The grinding range is planned based on the ulnar prosthesis parameters.

[0030] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the ulna anatomical axis is determined based on the following steps:

[0031] Slice the point cloud data corresponding to the ulna to obtain multiple ulna slices;

[0032] The centroid coordinates of each ulna slice are extracted, and a straight line is fitted to the centroid coordinates of each ulna slice to obtain the ulna anatomical axis.

[0033] According to a preoperative planning system for elbow replacement surgery provided by the present invention, the point cloud data corresponding to the ulna is determined based on the elbow joint model.

[0034] The elbow replacement surgery preoperative planning system provided by the present invention constructs an elbow joint model based on elbow joint CT data, so that an elbow joint coordinate system can be established based on the elbow joint model, and then based on the elbow joint coordinate system, preoperative planning of elbow replacement surgery can be performed quickly and accurately without relying on the doctor's clinical experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 It is a structural schematic diagram of the preoperative planning system for elbow replacement surgery provided by the present invention;

[0037] Figure 2 It is a schematic diagram of preoperative planning on the humeral side provided by the present invention;

[0038] Figure 3 It is a schematic diagram of preoperative planning on the ulnar side provided by the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Before traditional total elbow replacement surgery, the doctor needs to determine the axis of the elbow bone trunk, the elbow osteotomy area and the osteotomy path based on clinical experience. This surgery is highly dependent on the doctor's clinical experience, and the efficiency and accuracy of preoperative planning are low.

[0041] To this end, the present invention provides a preoperative planning system for elbow replacement surgery. Figure 1 FIG. 1 is a schematic diagram of the structure of the preoperative planning system for elbow replacement surgery provided by the present invention. Figure 1 As shown, the system includes:

[0042] A model building unit 110 is used to build an elbow joint model based on the elbow joint CT data;

[0043] A coordinate establishing unit 120, used for establishing an elbow joint coordinate system based on the elbow joint model;

[0044] The preoperative planning unit 130 is used to perform preoperative planning of elbow replacement surgery based on the elbow joint coordinate system.

[0045] Here, CT (Computed Tomography) data refers to image data generated by computer tomography. CT data includes X-ray images, which are the product of the combination of computer control, X-ray imaging, electromechanical technology and mathematics, and can provide three-dimensional structural information of the elbow joint. On this basis, an elbow joint model for characterizing the three-dimensional structural information of the elbow joint can be constructed based on the elbow joint CT data.

[0046] Optionally, a three-dimensional reconstruction model of the ulna, radius and distal end of the humerus can be constructed based on the CT data, that is, an elbow joint model can be obtained. The elbow joint CT data can be three-dimensionally reconstructed using the open source medical imaging analysis platform 3D Slicer to obtain the elbow joint model.

[0047] In addition, the elbow joint coordinate system is used to describe the position and direction of the elbow joint. Optionally, according to the elbow joint model, key axes (such as the anatomical axis of the humeral shaft, the line connecting the medial and lateral condyles of the humerus, the anatomical axis of the ulna, etc.) can be determined, and then the elbow joint coordinate system can be established according to the key axes.

[0048] After obtaining the elbow joint coordinate system, the position of the osteotomy area on the elbow joint, the needle insertion position and the grinding range can be known, and then the corresponding preoperative planning of elbow replacement surgery can be carried out.

[0049] It can be seen that the embodiment of the present invention constructs an elbow joint model based on the elbow joint CT data, so that an elbow joint coordinate system can be established based on the elbow joint model, and then based on the elbow joint coordinate system, preoperative planning of elbow replacement surgery can be performed quickly and accurately without relying on the doctor's clinical experience.

[0050] Based on the above embodiment, an elbow joint coordinate system is established based on the elbow joint model, including:

[0051] Convert the elbow joint model into point cloud data;

[0052] Based on the point cloud data, the anatomical axis of the humeral shaft and the line connecting the medial and lateral epicondyles of the humerus are determined; the line connecting the medial and lateral epicondyles of the humerus refers to the line connecting the medial epicondyle of the humerus and the lateral epicondyle of the humerus;

[0053] The elbow joint coordinate system was established based on the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus.

[0054] Specifically, point cloud data refers to a set of vectors in a three-dimensional coordinate system. Point cloud data can intuitively represent the shape, surface, texture and other information of objects in space. Point cloud data can use the PCL (Point Cloud Library) library to convert the elbow joint model into point cloud data.

[0055] Among them, the anatomical axis of the humeral shaft refers to the central axis of the humeral shaft, and the medial and lateral epicondyle line of the humerus refers to the line between the medial epicondyle of the humerus and the lateral epicondyle of the humerus.

[0056] Optionally, based on the point cloud data, the positions of each point on the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus can be determined, and a straight line fitting is performed on each point on the anatomical axis of the humeral shaft to obtain the anatomical axis of the humeral shaft.

[0057] After obtaining the anatomical axis of the humeral shaft, the X-axis, Y-axis, and Z-axis in the elbow joint coordinate system can be determined based on the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus, thereby establishing the elbow joint coordinate system.

[0058] Based on any of the above embodiments, the anatomical axis of the humeral shaft is determined based on the following steps:

[0059] Slicing the point cloud data corresponding to the humeral shaft to obtain a plurality of humeral shaft slices;

[0060] The centroid coordinates of each humeral shaft slice were extracted, and a straight line was fitted to the centroid coordinates of each humeral shaft slice to obtain the anatomical axis of the humeral shaft.

[0061] Specifically, point cloud data slicing processing refers to slicing point cloud data according to certain cutting rules to obtain multiple two-dimensional planes, so that specific areas in the point cloud data can be extracted. In point cloud data slicing processing, various algorithms can be used to determine the cutting rules, such as distance-based cutting, curvature-based cutting, etc.

[0062] After slicing the point cloud data corresponding to the humeral shaft, multiple humeral shaft slices can be obtained, the centroid coordinates of each humeral shaft slice are extracted, and the centroid coordinates of each humeral shaft slice are linearly fitted to obtain the anatomical axis of the humeral shaft.

[0063] Among them, the random sampling consensus algorithm, the overall least squares algorithm, the linear regression algorithm, etc. can be used for straight line fitting.

[0064] Based on any of the above embodiments, an elbow joint coordinate system is established based on the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus, including:

[0065] Determine the first vector based on the anatomical axis of the humeral shaft and the line connecting the internal and external condyles of the humerus;

[0066] Determine a second vector based on the first vector and the anatomical axis of the humeral shaft;

[0067] An elbow joint coordinate system is established based on the anatomical axis of the humeral shaft, the first vector and the second vector; the origin of the elbow joint coordinate system is the intersection of the curved surface where the olecranon fossa of the humerus is located and the anatomical axis of the humeral shaft.

[0068] In some specific embodiments, after determining the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus, the vector corresponding to the anatomical axis of the humeral shaft and the vector corresponding to the line connecting the medial and lateral condyles of the humerus are used to make a vector outer product to obtain a first vector Vercor1 (i.e., the vector corresponding to the X-axis of the elbow joint coordinate system). Next, the first vector Vector1 is used to make a vector outer product with the vector corresponding to the anatomical axis of the humeral shaft to obtain a second vector Vector2 (i.e., the vector corresponding to the Y-axis of the elbow joint coordinate system). Finally, the anatomical axis of the humeral shaft, the first vector Vector1, and the second vector Vector2 are used to construct an elbow joint coordinate system, and the origin of the coordinate system is the intersection of the curved surface where the olecranon fossa of the humerus is located and the anatomical axis of the humeral shaft.

[0069] Based on any of the above embodiments, the algorithms corresponding to the straight line fitting are the random sampling consensus algorithm and the global least squares algorithm.

[0070] Specifically, the RANdom SAmple Consensus (RANSAC) algorithm is an algorithm that estimates the parameters of a mathematical model in an iterative manner based on a set of sample data containing abnormal data, calculates the mathematical model parameters of the data, and obtains valid sample data. RANSAC is an iterative algorithm used to estimate the parameters of a mathematical model from data containing outliers, and achieves this goal by repeatedly selecting a set of random subsets from the data.

[0071] Global Least Squares (GLS) is an algorithm used to solve linear regression problems. It estimates model parameters by minimizing the residual sum of squares. The GLS algorithm can handle large-scale data sets and has high accuracy. The following are the basic steps of the GLS algorithm:

[0072] Step 1. Initialization: Select a suitable initial value as the model parameter.

[0073] Step 2: Calculate the residual: For each observation, calculate the difference between its true value and the model predicted value.

[0074] Step 3: Calculate the covariance matrix: Calculate the covariance matrix based on the observed values ​​and model parameters.

[0075] Step 4: Calculate the generalized covariance matrix: Expand the covariance matrix to include all observations and model parameters.

[0076] Step 5: Calculate the generalized inverse matrix: Use Gaussian elimination or LU decomposition to solve the generalized inverse matrix.

[0077] Step 6: Calculate model parameters: Use the generalized inverse matrix and residual vector to calculate model parameters.

[0078] Repeat steps 2-6 until the convergence condition is met or the maximum number of iterations is reached.

[0079] Based on any of the above embodiments, preoperative planning of elbow replacement surgery is performed based on the elbow joint coordinate system, including:

[0080] Plan the osteotomy area based on the elbow joint coordinate system and the humeral osteotomy plate parameters;

[0081] The needle insertion direction and grinding range are planned based on the anatomical axis of the ulna and the parameters of the ulnar prosthesis.

[0082] Specifically, the humeral osteotomy plate is usually made of stainless steel and is usually placed in the osteotomy area to fix the humerus and help restore the fracture site. The humeral osteotomy plate parameters may include the distance between two parallel planes of the humeral osteotomy plate, the angle between the other two intersecting planes of the humeral osteotomy plate, etc.

[0083] According to the parameters of the humeral osteotomy plate and the elbow joint coordinate system, the position of the osteotomy area in the elbow joint coordinate system can be determined, that is, the position of the osteotomy area can be planned.

[0084] In addition, the ulnar prosthesis includes a humero-ulnar joint prosthesis. The ulnar prosthesis parameters may include the length of the ulnar prosthesis. The needle insertion direction refers to the needle insertion direction when the ulnar medullary cavity is opened on the ulnar side, and the grinding range refers to the corresponding grinding range when the ulnar prosthesis is installed.

[0085] Optionally, the needle insertion direction can be determined according to the anatomical axis of the ulna, and the grinding range can be determined according to the parameters of the ulna prosthesis.

[0086] Based on any of the above embodiments, the humeral osteotomy plate parameters include the distance between two parallel planes of the humeral osteotomy plate and the angle between two other intersecting planes of the humeral osteotomy plate;

[0087] Based on the elbow joint coordinate system and the humeral osteotomy plate parameters, the osteotomy area is planned, including:

[0088] Based on the elbow joint coordinate system and the distance between the two parallel planes of the humeral osteotomy plate, the positions of two mutually parallel cutting planes in the osteotomy area are planned;

[0089] Based on the position of the lowest point of the olecranon fossa, the elbow joint coordinate system, and the angle between the other two intersecting planes of the humeral osteotomy plate, the positions of the two inclined planes in the osteotomy area are determined.

[0090] In some specific embodiments, Figure 2 As shown, there are four cutting planes corresponding to the osteotomy area, two of which are parallel to each other, perpendicular to the Y axis of the elbow joint coordinate system (the coordinate axis corresponding to the second vector) and parallel to the anatomical axis of the humeral shaft of the elbow joint coordinate system, and the distance between the two cutting planes is determined based on the distance between the two parallel planes of the humeral osteotomy plate (i.e., plane 1 and plane 2). The other two cutting planes are inclined planes, passing through the lowest point of the olecranon fossa and perpendicular to the YOZ plane of the elbow joint coordinate system (the X axis is the coordinate axis corresponding to the first vector, the Y axis is the coordinate axis corresponding to the second vector, the Z axis is the coordinate axis corresponding to the anatomical axis of the humeral shaft, and O is the origin of the elbow joint coordinate system), and the two cutting planes form a "V"-shaped angle, and the angle of the angle is determined based on the angle (i.e., α) between the other two intersecting planes of the humeral osteotomy plate.

[0091] Based on any of the above embodiments, the needle insertion direction and grinding range are planned based on the anatomical axis of the ulna and the parameters of the ulna prosthesis, including:

[0092] Plan the direction of needle insertion based on the anatomical axis of the ulna and the base of the coracoid process;

[0093] Based on the ulnar prosthesis parameters, the grinding range is planned.

[0094] Specifically, the ulnar prosthesis generally includes a humero-ulnar joint prosthesis. The ulnar prosthesis parameters may include the length of the ulnar prosthesis. The needle insertion direction refers to the needle insertion direction when the ulnar medullary cavity is opened on the ulnar side, and the grinding range refers to the corresponding grinding range when the ulnar prosthesis is installed.

[0095] In some specific embodiments, Figure 3 As shown in the figure, for the ulnar side, the needle insertion direction is parallel to the anatomical axis of the ulna, and the needle insertion point is the intersection of the anatomical axis of the ulna and the base of the coracoid process. On this basis, according to the ulnar prosthesis parameters, the position of the grinding range can be determined on the elbow joint coordinate system, that is, the grinding range is planned.

[0096] Based on any of the above embodiments, the anatomical axis of the ulna is determined based on the following steps:

[0097] Slice the point cloud data corresponding to the ulna to obtain multiple ulna slices;

[0098] The centroid coordinates of each ulna slice were extracted, and a straight line was fitted to the centroid coordinates of each ulna slice to obtain the anatomical axis of the ulna.

[0099] Here, the anatomical axis of the ulna refers to the central axis of the ulna. Point cloud data slicing processing refers to cutting point cloud data according to certain cutting rules to obtain multiple two-dimensional planes, so that specific areas in the point cloud data can be extracted. Among them, in the point cloud data slicing processing, various algorithms can be used to determine the cutting rules, such as distance-based cutting, curvature-based cutting, etc.

[0100] After slicing the point cloud data corresponding to the ulna, multiple ulna slices can be obtained, the centroid coordinates of each ulna slice are extracted, and the centroid coordinates of each ulna slice are linearly fitted to obtain the anatomical axis of the ulna.

[0101] Based on any of the above embodiments, the point cloud data corresponding to the ulna is determined based on the elbow joint model.

[0102] Specifically, point cloud data refers to a set of vectors in a three-dimensional coordinate system. Point cloud data can intuitively represent the shape, surface, and texture of objects in space. The PCL library can be used to convert the elbow joint model into point cloud data, so that the point cloud data corresponding to the ulna can be extracted.

[0103] It can be seen that the embodiment of the present invention adopts CT technology to obtain elbow joint CT data, and the CT data of the ulna, humeral shaft and humeral epicondyle can be obtained according to the elbow joint CT data, and the 3D models of the ulna, humeral shaft and humeral epicondyle are constructed by using the CT data of the ulna, humeral shaft and humeral epicondyle, and the 3D model is converted into point cloud data for processing; the anatomical axis of the humeral shaft, the connecting line of the medial and lateral condyles of the humerus and the anatomical axis of the ulna are respectively extracted by using the 3D point cloud processing method, and the elbow joint coordinate system is constructed according to the anatomical axis of the humeral shaft and the connecting line of the medial and lateral condyles of the humerus; finally, according to the elbow joint coordinate system, the anatomical axis of the ulna, the ulna prosthesis parameters and the humeral osteotomy plate parameters, the osteotomy area on the humeral side, the needle insertion direction and the grinding range on the ulnar side are planned, so that the preoperative planning of elbow replacement surgery can be carried out quickly and accurately without relying on the doctor's clinical experience.

[0104] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0105] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preoperative planning system for elbow replacement surgery, characterized in that: include: A model building unit, used for building an elbow joint model based on elbow joint CT data; A coordinate establishing unit, used for establishing an elbow joint coordinate system based on the elbow joint model; A preoperative planning unit, used for performing preoperative planning of elbow replacement surgery based on the elbow joint coordinate system; The step of establishing an elbow joint coordinate system based on the elbow joint model comprises: Converting the elbow joint model into point cloud data; Based on the point cloud data, determining the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus; the line connecting the medial and lateral condyles of the humerus refers to the line connecting the medial epicondyle of the humerus and the lateral epicondyle of the humerus; Establishing the elbow joint coordinate system based on the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus; The step of establishing the elbow joint coordinate system based on the anatomical axis of the humeral shaft and the line connecting the medial and lateral condyles of the humerus comprises: Performing a vector outer product on the vector corresponding to the anatomical axis of the humeral shaft and the vector corresponding to the line connecting the medial and lateral condyles of the humerus to determine a first vector; Performing a vector outer product between the first vector and the vector corresponding to the anatomical axis of the humeral shaft to determine a second vector; Based on the anatomical axis of the humeral shaft, the first vector and the second vector, the elbow joint coordinate system is established; the origin of the elbow joint coordinate system is the intersection of the curved surface where the olecranon fossa of the humerus is located and the anatomical axis of the humeral shaft; The preoperative planning of elbow replacement surgery based on the elbow joint coordinate system includes: Planning the osteotomy area based on the elbow joint coordinate system and the humeral osteotomy plate parameters; Plan the needle insertion direction and grinding range based on the anatomical axis of the ulna and the parameters of the ulna prosthesis; The humeral osteotomy plate parameters include the distance between two parallel planes of the humeral osteotomy plate and the angle between the other two intersecting planes of the humeral osteotomy plate; The step of planning the osteotomy area based on the elbow joint coordinate system and the humeral osteotomy plate parameters includes: Based on the elbow joint coordinate system and the distance between the two parallel planes of the humeral osteotomy plate, planning the positions of two mutually parallel cutting planes in the osteotomy area; Determine the positions of two inclined planes in the osteotomy area based on the lowest point position of the olecranon fossa, the elbow joint coordinate system, and the angle between the other two intersecting planes of the humeral osteotomy plate; The needle insertion direction and grinding range are planned based on the anatomical axis of the ulna and the parameters of the ulna prosthesis, including: The needle insertion direction is planned based on the anatomical axis of the ulna and the position of the base of the coracoid process; Planning the grinding range based on the ulnar prosthesis parameters; The anatomical axis of the ulna is determined based on the following steps: Slice the point cloud data corresponding to the ulna to obtain multiple ulna slices; The centroid coordinates of each ulna slice are extracted, and a straight line is fitted to the centroid coordinates of each ulna slice to obtain the ulna anatomical axis.

2. The preoperative planning system for elbow replacement surgery according to claim 1, characterized in that: The anatomical axis of the humeral shaft is determined based on the following steps: Slicing the point cloud data corresponding to the humeral shaft to obtain a plurality of humeral shaft slices; The centroid coordinates of each humeral shaft slice are extracted, and a straight line fitting is performed on the centroid coordinates of each humeral shaft slice to obtain the anatomical axis of the humeral shaft.

3. The preoperative planning system for elbow replacement surgery according to claim 2, characterized in that: The algorithms corresponding to the straight line fitting are the random sampling consensus algorithm and the overall least squares algorithm.

4. The preoperative planning system for elbow replacement surgery according to claim 1, characterized in that: The point cloud data corresponding to the ulna is determined based on the elbow joint model.

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