An automatic femoral stem prosthesis recommendation method for total hip replacement surgery

Abstract

The application provides a femoral stem prosthesis automatic recommendation method for total hip replacement surgery, comprising the following steps: acquiring three-dimensional CT image data of a patient, segmenting a hip bone, a femur and a surgical side medullary cavity through a neural network model; generating bone key points using a key point generation network; traversing all available femoral stems, performing initial positioning on each femoral stem, and evaluating according to three evaluation indexes; adjusting the pose of each femoral stem using three strategies, re-evaluating after the adjustment is completed, and obtaining four groups of evaluation information of each femoral stem; sorting and screening all the above evaluation information, and selecting the optimal femoral stem model and the corresponding placement pose. The method described in the application analyzes based on a three-dimensional model, and the evaluation indexes are also designed in a three-dimensional space, so that the prosthesis recommendation is more accurate, in addition, the application can realize the automation of prosthesis recommendation, avoiding the introduction of human error.

Description

Technical Field

[0001] This invention relates to the field of medical technology, specifically to an automatic method for recommending femoral stem prostheses for total hip replacement surgery. Background Technology

[0002] Hip replacement surgery is one of the most effective methods for treating degenerative hip joint diseases and improving patients' quality of life. With the increasing prominence of China's aging population, the practical significance of hip replacement surgery is even more pronounced. Successful hip replacement surgery relies on accurate, comprehensive, and detailed surgical planning, among which choosing the appropriate prosthesis brand and model is particularly important.

[0003] Patent CN114587583A provides a method for intraoperative prosthesis recommendation in a knee joint surgery navigation system. This method requires the surgeon to use a probe to locate bone registration points. Then, the system calculates data based on the combination of parameters of the location points to obtain femoral prosthesis model parameters, femoral prosthesis varus / valgus angle, femoral prosthesis internal / external rotation angle, femoral prosthesis positioning parameters, and tibial prosthesis model parameters. Finally, based on these parameters, the specific model of the prosthesis to be recommended is determined. Although this method can recommend the prosthesis model, the process is complex and requires the surgeon to manually select key points. This not only depends on the surgeon's experience and familiarity with the relevant software, but also takes a long time and is prone to human error.

[0004] Patent CN113744214A provides a method, device, and electronic device for femoral stem placement based on deep reinforcement learning. However, this method uses two-dimensional images, lacking spatial information from three-dimensional images. Furthermore, the recommended femoral stem uses adjustment signals output by DDQN, which can increase or decrease the model size, or shift the position upwards or downwards. The traversal of states by reinforcement learning is limited; for example, the model states mentioned in the solution are only 13 types, S0 to S12. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art described in the background section and provide an automatic recommendation method for femoral stem prostheses in total hip replacement surgery. This method iterates through all femoral stems, records the initial positioning and evaluation indicators of each stem after adjusting its position using three strategies, and compares these records to find the femoral stem model and position with the optimal evaluation indicators.

[0006] To achieve the above objectives, the present invention employs the following technical solution: an automatic recommendation method for femoral stem prostheses in total hip replacement surgery, comprising the following steps:

[0007] Acquire the patient's 3D CT image data, segment the hip bone, femur, and surgical side medullary canal using a neural network model, and extract the surface of the medullary canal;

[0008] The corresponding region in the 3D image is cropped and used as the input to the keypoint generation network, which then generates skeletal keypoints.

[0009] Iterate through all available femoral stems, perform initial positioning for each femoral stem, and evaluate it according to three evaluation indicators;

[0010] Based on the information generated during the evaluation process, the adjustment direction of each femoral stem is provided. Three strategies are used to adjust the pose of each femoral stem. After the adjustment is completed, the evaluation is performed again to obtain four sets of evaluation information for each femoral stem.

[0011] All the above evaluation information is sorted and filtered to select the optimal femoral stem model and corresponding placement position.

[0012] Furthermore, the generated skeletal key points include:

[0013] The femoral head center, medial femoral epicondyle, and lateral femoral epicondyle are used to establish the femoral coordinate system;

[0014] The center of the femoral head on the surgical side, the proximal end of the femoral medullary cavity, and the distal end of the femoral medullary cavity are used for the initial positioning of the femoral stem when placing it.

[0015] The minor trochanter point is used to calculate the constraint evaluation index after the femoral stem is placed.

[0016] Furthermore, the initial positioning of each femoral stem includes:

[0017] The midline of the medullary cavity is determined by the proximal and distal ends of the femoral medullary cavity on the surgical side.

[0018] Place the femoral stem into the femur so that the axis of the femoral stem shaft coincides with the axis of the medullary cavity;

[0019] Rotate the current femoral stem around the axis of the femoral stem shaft so that the plane containing the axis of the femoral stem neck and shaft passes through the center of the femoral head ball;

[0020] Move the femoral stem up and down along the axis of the femoral stem shaft so that the extension line of the femoral stem neck axis passes through the center of the femoral head.

[0021] Furthermore, the three evaluation indicators include:

[0022] Constraint criterion 1: The distance from the lesser trochanter point to the femoral osteotomy surface is within the range of 1-1.5cm;

[0023] Constraint index two: the relative positional relationship between the femoral stem and the medullary cavity;

[0024] Evaluation index: the ratio of the intercept of the line segment formed by the intersection of the straight line along the femoral stem x-axis and the intersection of the femoral stem surface and the medullary canal surface.

[0025] Furthermore, the first constraint index, the distance from the lesser trochanter point to the femoral osteotomy surface, can be calculated by projecting the line connecting the lesser trochanter point, the femoral osteotomy surface, and the axis of the femoral stem neck onto the normal vector of the femoral osteotomy surface. The specific process is as follows:

[0026] Let L denote the lesser trochanter point, and E denote the intersection of the femoral osteotomy surface and the axis of the femoral stem neck. Then the length of this line segment is expressed as: The midline of the femoral stem neck is perpendicular to the femoral osteotomy surface. Let the normal vector of the femoral osteotomy surface be denoted as . ,but exist The projection on the surface is the distance d from the lesser trochanter to the femoral osteotomy surface:

[0027]

[0028] Furthermore, the second constraint indicator, the relative positional relationship between the femoral stem and the medullary canal, includes:

[0029] Two parallel planes are created through the origin of the femoral stem and the bottom of the femoral stem. These two planes are used to cut the medullary canal and the femoral stem. The upper plane is the XOY plane of the femoral stem, and the lower plane passes through the vertex of the bottom of the femoral stem shaft.

[0030] To determine whether the surface data between the upper and lower planes of the femoral stem is included within the corresponding medullary canal surface data, the number of points of the femoral stem surface data outside the medullary canal surface data is calculated.

[0031] If all femoral stem surface data are within the medullary canal surface data, then the number of femoral stem surface data points outside the medullary canal surface data is 0; if the femoral stem surface data are not included within the medullary canal surface data, then the number of femoral stem surface data points outside the medullary canal surface data is greater than 0.

[0032] Furthermore, the evaluation index, the intercept ratio of the line segment formed by the intersection points of the femoral stem x-axis line and the femoral stem surface and medullary canal surface, includes:

[0033] In the XOY plane of the femoral stem, there are two intersecting straight lines, passing through the x-axis and y-axis of the femoral stem, respectively. The two intersection points of the line passing through the x-axis of the femoral stem with the femoral stem are denoted as follows: and The two intersections with the medullary cavity are denoted as follows: and ,ratio These are the evaluation indicators:

[0034]

[0035] Furthermore, the use of three strategies to adjust the pose of each femoral stem includes:

[0036] Adjustments are made based on the intersection of the femoral stem x-axis and surface data;

[0037] Adjustments are made based on the intersection of the femoral stem's y-axis and the surface data.

[0038] Adjustments are made based on the direction of the long axis of the profile determined by the intersection of the plane at the bottom of the femoral stem and the surface of the medullary cavity.

[0039] Furthermore, the adjustment based on the intersection of the femoral stem x-axis and surface data includes:

[0040] remember The vector that needs to be translated along the x-axis of the femoral stem:

[0041]

[0042] Let the coordinates of the origin of the femoral stem be... The coordinates of the base of the femoral stem are The height from the origin of the femoral stem to the bottom of the femoral stem is h, and the angle by which the femoral stem needs to rotate around the y-axis is... ,in,

[0043]

[0044] Rotational transformations are performed around the base of the femoral stem, with the y-axis of the femoral stem as the axis of rotation. Specifically, this includes:

[0045] The femoral stem is translated by a distance of... Translation transformation The rotation angle is Rotational transformation Translational displacement is Translation transformation That is, applying a transformation to the femoral stem. Move the femoral stem to the position that needs adjustment;

[0046] The adjustment makes the distance from the two femoral stem surfaces to the corresponding medullary canal equal in the x-axis direction, and adjusts the femoral stem surface that extends beyond the medullary canal surface to be inside the medullary canal surface.

[0047] Furthermore, the adjustment based on the intersection of the femoral stem y-axis and surface data includes:

[0048] The two points where the straight line passing through the y-axis of the femoral stem in the XOY plane intersects the femoral stem are denoted as follows: and The two intersections with the medullary cavity are denoted as follows: and ,remember The vector that needs to be translated along the y-axis:

[0049]

[0050] The angle by which the femoral stem needs to rotate about the x-axis is: :

[0051]

[0052] Rotational transformations are performed around the base of the femoral stem, with the x-axis of the femoral stem as the axis of rotation. Specifically, this includes:

[0053] The femoral stem is translated by a distance of... Translation transformation The rotation angle is Rotational transformation Translational displacement is Translation transformation That is, applying a transformation to the femoral stem. Move the femoral stem to the position that needs adjustment;

[0054] The adjustment makes the distance from the two femoral stem surfaces to the corresponding medullary canal equal in the y-axis direction, and adjusts the femoral stem surface that extends beyond the medullary canal surface to be inside the medullary canal surface.

[0055] Furthermore, the adjustment based on the long axis direction of the contour determined by the intersection of the plane at the base of the femoral stem and the surface of the medullary cavity includes:

[0056] The intersection of the plane at the base of the femoral stem and the surface of the medullary canal is approximately elliptical, and the direction of the major axis is calculated using the minimum circumscribed rectangle.

[0057] Let the angle between the long axis of the femoral stem base and the long axis of the medullary canal cross-section be . Apply a rotation about the z-axis to the femoral stem Rotational transformation of angle ;

[0058] Adjust the long axis of the bottom of the femoral stem to align with the long axis of the bottom of the medullary cavity, so that the portion of the femoral stem that extends beyond the surface of the medullary cavity returns to the inside of the medullary cavity.

[0059] Furthermore, the process of sorting and filtering all the above evaluation information to select the optimal femoral stem model and corresponding placement includes:

[0060] Based on the constraint index, select the femoral stem type and pose combination that satisfies the constraint or has the smallest distance d from the lesser trochanter to the femoral osteotomy surface.

[0061] The femoral stem type and position combination selected based on constraint index one will be further selected based on constraint index two to identify the femoral stem type and position combination with 0 or the fewest extramedullary femoral stem points.

[0062] The femoral stem type and position combination selected based on constraint index 2 will be further selected using evaluation index to identify the femoral stem type and position combination with the largest ratio r.

[0063] Further, the step of selecting the femoral stem type and pose combination that satisfies the constraint or has the smallest distance d from the lesser trochanter to the femoral osteotomy surface according to constraint index one includes:

[0064] The brand series and models of the femoral stem are distinguished according to whether the distance d from the lesser trochanter to the femoral osteotomy surface is within or outside the permissible range;

[0065] When there are permissible femoral stem and position, all femoral stem and position within the permissible range are subject to the screening of constraint index two.

[0066] When there are no femoral stems and positions within the permissible range, the femoral stem type and position combination with the smallest distance outside the permissible range are selected as candidates for inclusion in the second constraint index screening.

[0067] Furthermore, the step of further selecting the femoral stem type and position combination selected based on constraint index one, and then further selecting the femoral stem type and position combination with zero or minimal extramedullary femoral stem point counts based on constraint index two, includes:

[0068] The femoral stem models and positions selected based on constraint index one will be further selected based on constraint index two. The brand series models of the femoral stem will be arranged in ascending order of the number of points on the surface of the femoral stem outside the medullary canal.

[0069] When there are femoral stems that are completely contained within the medullary canal, these femoral stems are included in the screening of evaluative indicators.

[0070] When no femoral stem is completely contained within the medullary canal surface, the femoral stem with the fewest points outside the medullary canal surface is selected for screening of evaluation indicators.

[0071] Furthermore, the step of further selecting the femoral stem type and pose combination with the largest ratio r based on the femoral stem type and pose combination selected according to the second constraint index through the evaluation index includes:

[0072] The femoral stem and position selected from the second constraint index are then selected for the evaluation index. The femoral stems of different brands and series are sorted from largest to smallest r, and the femoral stem model and position with the largest r are selected, thus selecting the best femoral stem model and position.

[0073] This invention provides an automated method for recommending femoral stem prostheses for total hip replacement surgery. This method iterates through all available models or all models of femoral stems from a specified brand, records four sets of evaluation information for each femoral stem after initial positioning and three strategies for adjusting the posture, and compares these with all evaluation indicators to automatically recommend the optimal femoral stem model and posture. Compared with existing technologies, the method of this invention is based on a three-dimensional model for analysis, and the evaluation indicators are also designed in three-dimensional space, making the prosthesis recommendation more accurate. Furthermore, this invention automates the prosthesis recommendation process, avoiding human error. Attached Figure Description

[0074] The features, advantages and technical effects of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0075] Figure 1 This is a flowchart illustrating the automatic recommendation method for femoral stem prosthesis in total hip replacement surgery provided in this embodiment of the invention.

[0076] Figure 2 This is a schematic diagram of creating two parallel planes through the origin of the femoral stem and the bottom of the femoral stem, as provided in an embodiment of the present invention.

[0077] Figure 3 This is a cross-sectional view of the femoral stem at the XOY plane provided in an embodiment of the present invention. Detailed Implementation

[0078] The features and exemplary embodiments of various aspects of this disclosure will now be described in detail. To make the objectives, technical solutions, and advantages of this disclosure clearer, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are intended to explain this disclosure only and not to limit it. For those skilled in the art, this disclosure can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this disclosure by illustrating examples.

[0079] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0080] In this document, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "assembly" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0081] To better understand the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0082] Figure 1 This is a flowchart illustrating the automatic recommendation method for femoral stem prostheses in total hip replacement surgery provided in this embodiment of the invention.

[0083] like Figure 1 As shown, the present invention provides an automatic recommendation method for femoral stem prostheses in total hip replacement surgery, comprising the following steps:

[0084] S101: Acquire the patient's three-dimensional CT image data, segment the hip bone, femur, and surgical side medullary canal using a neural network model, and extract the surface of the medullary canal;

[0085] S102, crop the corresponding region in the 3D image as input to the keypoint generation network, and use the keypoint generation network to generate skeletal keypoints;

[0086] S103, Traverse all available femoral stems, perform initial positioning for each femoral stem, and evaluate it according to three evaluation indicators;

[0087] S104. Based on the information generated during the evaluation process, the adjustment direction of each femoral stem is provided. Three strategies are used to adjust the pose of each femoral stem. After the adjustment is completed, the evaluation is performed again to obtain four sets of evaluation information for each femoral stem.

[0088] S105, sort and filter all the above evaluation information, and select the optimal femoral stem model and corresponding placement position.

[0089] As an optional implementation, the neural network in S101 is at least one of FCN, SegNet, ENet, CRFAsRNN, PSPNet, ParseNet, RefineNet, 3D-UNet, and nnU-Net.

[0090] As an optional implementation, the key points described in S102 are obtained by coordinate regression through a neural network, and the network model involved includes DSNT, etc.

[0091] As an optional implementation, the key points described in S102 can also be processed by heatmap regression overlay. The heatmap regression network includes at least one of SCN, 3D-UNet, and nnU-Net.

[0092] As an optional implementation, the generated skeletal key points in S102 include:

[0093] The femoral head center, medial femoral epicondyle, and lateral femoral epicondyle are used to establish the femoral coordinate system;

[0094] The center of the femoral head on the surgical side, the proximal end of the femoral medullary cavity, and the distal end of the femoral medullary cavity are used for the initial positioning of the femoral stem when placing it.

[0095] The minor trochanter point is used to calculate the constraint evaluation index after the femoral stem is placed.

[0096] As an optional implementation, the initial positioning of each femoral stem in S103 includes:

[0097] The midline of the medullary cavity is determined by the proximal and distal ends of the femoral medullary cavity on the surgical side.

[0098] Place the femoral stem into the femur so that the axis of the femoral stem shaft coincides with the axis of the medullary cavity;

[0099] Rotate the current femoral stem around the axis of the femoral stem shaft so that the plane containing the femoral stem neck and shaft passes through the center of the femoral head ball;

[0100] Move the femoral stem up and down along the axis of the femoral stem shaft so that the extension line of the femoral stem neck axis passes through the center of the femoral head.

[0101] As an optional implementation, the three evaluation indicators in S103 include:

[0102] Constraint criterion 1: The distance from the lesser trochanter point to the femoral osteotomy surface is within the range of 1-1.5cm;

[0103] Constraint index two: the relative positional relationship between the femoral stem and the medullary cavity;

[0104] Evaluation index: the ratio of the intercept of the line segment formed by the intersection of the straight line along the femoral stem x-axis and the intersection of the femoral stem surface and the medullary canal surface.

[0105] As an optional implementation, the first constraint index, the distance from the lesser trochanter point to the femoral osteotomy surface, can be calculated by projecting the line connecting the lesser trochanter point, the femoral osteotomy surface, and the axis of the femoral stem neck onto the normal vector of the femoral osteotomy surface. The specific process is as follows:

[0106] Let L denote the lesser trochanter point, and E denote the intersection of the femoral osteotomy surface and the axis of the femoral stem neck. Then the length of this line segment is expressed as: The midline of the femoral stem neck is perpendicular to the femoral osteotomy surface. Let the normal vector of the femoral osteotomy surface be denoted as . ,but exist The projection on the surface is the distance d from the lesser trochanter to the femoral osteotomy surface:

[0107]

[0108] As an optional implementation, the second constraint index, the relative positional relationship between the femoral stem and the medullary cavity, includes:

[0109] like Figure 2 As shown, two parallel planes are created through the origin of the femoral stem and the bottom of the femoral stem. These two planes are used to cut the medullary canal and the femoral stem. The upper plane is the femoral stem XOY plane, and the lower plane passes through the vertex of the bottom of the femoral stem shaft.

[0110] To determine whether the surface data between the upper and lower planes of the femoral stem is included within the corresponding medullary canal surface data, the number of points of the femoral stem surface data outside the medullary canal surface data is calculated.

[0111] If all femoral stem surface data are within the medullary canal surface data, then the number of femoral stem surface data points outside the medullary canal surface data is 0; if the femoral stem surface data are not included within the medullary canal surface data, then the number of femoral stem surface data points outside the medullary canal surface data is greater than 0.

[0112] As an optional implementation, the evaluation index—the intercept ratio of the line segment formed by the intersection points of the femoral stem x-axis and the femoral stem surface and medullary canal surface—includes:

[0113] like Figure 3 As shown, there are two intersecting straight lines in the XOY plane of the femoral stem, passing through the x-axis and y-axis of the femoral stem respectively. The two intersection points of the line passing through the x-axis of the femoral stem with the femoral stem are denoted as follows: and The two intersections with the medullary cavity are denoted as follows: and ,ratio These are the evaluation indicators:

[0114]

[0115] As an optional implementation, S104 describes using three strategies to adjust the pose of each femoral stem, including:

[0116] Adjustments are made based on the intersection of the femoral stem x-axis and surface data;

[0117] Adjustments are made based on the intersection of the femoral stem's y-axis and the surface data.

[0118] Adjustments are made based on the direction of the long axis of the profile determined by the intersection of the plane at the bottom of the femoral stem and the surface of the medullary cavity.

[0119] As an optional implementation, the adjustment based on the intersection of the femoral stem x-axis and surface data includes:

[0120] remember The vector that needs to be translated along the x-axis of the femoral stem:

[0121]

[0122] Let the coordinates of the origin of the femoral stem be... The coordinates of the base of the femoral stem are The height from the origin of the femoral stem to the bottom of the femoral stem is h, and the angle by which the femoral stem needs to rotate around the y-axis is... ,in,

[0123]

[0124] Rotational transformations are performed around the base of the femoral stem, with the y-axis of the femoral stem as the axis of rotation. Specifically, this includes:

[0125] The femoral stem is translated by a distance of... Translation transformation The rotation angle is Rotational transformation Translational displacement is Translation transformation That is, applying a transformation to the femoral stem. Move the femoral stem to the position that needs adjustment;

[0126] The adjustment makes the distance from the two femoral stem surfaces to the corresponding medullary canal equal in the x-axis direction, and adjusts the femoral stem surface that extends beyond the medullary canal surface to be inside the medullary canal surface.

[0127] As an optional implementation, the adjustment based on the intersection of the femoral stem y-axis and surface data includes:

[0128] like Figure 3 As shown, the two intersection points of the straight line passing through the y-axis of the femoral stem in the XOY plane with the femoral stem are denoted as follows: and The two intersections with the medullary cavity are denoted as follows: and ,remember The vector that needs to be translated along the y-axis:

[0129]

[0130] The angle by which the femoral stem needs to rotate about the x-axis is: :

[0131]

[0132] Rotational transformations are performed around the base of the femoral stem, with the x-axis of the femoral stem as the axis of rotation. Specifically, this includes:

[0133] The femoral stem is translated by a distance of... Translation transformation The rotation angle is Rotational transformation Translational displacement is Translation transformation That is, applying a transformation to the femoral stem. Move the femoral stem to the position that needs adjustment;

[0134] The adjustment makes the distance from the two femoral stem surfaces to the corresponding medullary canal equal in the y-axis direction, and adjusts the femoral stem surface that extends beyond the medullary canal surface to be inside the medullary canal surface.

[0135] As an optional implementation, the adjustment based on the long axis direction of the contour determined by the intersection of the plane at the base of the femoral stem and the surface of the medullary cavity includes:

[0136] The intersection of the plane at the base of the femoral stem and the surface of the medullary canal is approximately elliptical, and the direction of the major axis is calculated using the minimum circumscribed rectangle.

[0137] Let the angle between the long axis of the femoral stem base and the long axis of the medullary canal cross-section be . Apply a rotation about the z-axis to the femoral stem Rotational transformation of angle ;

[0138] Adjust the long axis of the bottom of the femoral stem to align with the long axis of the bottom of the medullary cavity, so that the portion of the femoral stem that extends beyond the surface of the medullary cavity returns to the inside of the medullary cavity.

[0139] As an optional implementation, the process described in S105, which involves sorting and filtering all the aforementioned evaluation information to select the optimal femoral stem model and corresponding placement, includes:

[0140] Based on the constraint index, select the femoral stem type and pose combination that satisfies the constraint or has the smallest distance d from the lesser trochanter to the femoral osteotomy surface.

[0141] The femoral stem type and position combination selected based on constraint index one will be further selected based on constraint index two to identify the femoral stem type and position combination with 0 or the fewest extramedullary femoral stem points.

[0142] The femoral stem type and position combination selected based on constraint index 2 will be further selected using evaluation index to identify the femoral stem type and position combination with the largest ratio r.

[0143] As an optional implementation, the step of selecting the femoral stem type and pose combination that satisfies the constraint or has the smallest distance d from the lesser trochanter to the femoral osteotomy surface according to constraint index one includes:

[0144] The brand series and models of the femoral stem are distinguished according to whether the distance d from the lesser trochanter to the femoral osteotomy surface is within or outside the permissible range;

[0145] When there are permissible femoral stem and position, all femoral stem and position within the permissible range are subject to the screening of constraint index two.

[0146] When there are no femoral stems and positions within the permissible range, the femoral stem type and position combination with the smallest distance outside the permissible range are selected as candidates for inclusion in the second constraint index screening.

[0147] As an optional implementation, the step of further selecting the femoral stem type and pose combination with zero or minimal extramedullary femoral stem point counts based on the femoral stem type and pose combination selected according to constraint index one, and then selecting the femoral stem type and pose combination with zero or minimal extramedullary femoral stem point counts based on constraint index two, includes:

[0148] The femoral stem models and positions selected based on constraint index one will be further selected based on constraint index two. The brand series models of the femoral stem will be arranged in ascending order of the number of points on the surface of the femoral stem outside the medullary canal.

[0149] When there are femoral stems that are completely contained within the medullary canal, these femoral stems are included in the screening of evaluative indicators.

[0150] When no femoral stem is completely contained within the medullary canal surface, the femoral stem with the fewest points outside the medullary canal surface is selected for screening of evaluation indicators.

[0151] As an optional implementation, the step of further selecting the femoral stem type and pose combination with the largest ratio r based on the femoral stem type and pose combination selected according to the second constraint index through an evaluation index includes:

[0152] The femoral stem and position selected from the second constraint index are then selected for the evaluation index. The femoral stems of different brands and series are sorted from largest to smallest r, and the femoral stem model and position with the largest r are selected, thus selecting the best femoral stem model and position.

[0153] This invention provides an automated method for recommending femoral stem prostheses for total hip replacement surgery. This method iterates through all available models or all models of femoral stems from a specified brand, records four sets of evaluation information for each femoral stem after initial positioning and three strategies for adjusting the posture, and compares these with all evaluation indicators to automatically recommend the optimal femoral stem model and posture. Compared with existing technologies, the method of this invention is based on a three-dimensional model for analysis, and the evaluation indicators are also designed in three-dimensional space, making the prosthesis recommendation more accurate. Furthermore, this invention automates the prosthesis recommendation process, avoiding human error.

[0154] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A femoral stem prosthesis automatic recommendation method for total hip replacement surgery, characterized by, The method comprises the following steps: S101, acquiring three-dimensional CT image data of a patient, segmenting a hip bone, a femur and a surgical-side medullary cavity through a neural network model, and extracting a medullary cavity surface; S102, cropping a corresponding region in the three-dimensional image as an input of a key point generation network, and generating bone key points by using the key point generation network; S103, traversing all available femoral stems, performing initial positioning on each femoral stem, and evaluating according to three evaluation indexes; S104, providing adjustment directions of each femoral stem according to information generated in the evaluation process, adjusting the pose of each femoral stem by using three strategies, and performing evaluation again after adjustment to obtain four sets of evaluation information of each femoral stem; S105, sorting and screening all the above evaluation information, and selecting an optimal femoral stem model and a corresponding placement pose; The three evaluation indexes in S103 include: Constraint index one: the distance between the lesser trochanter point and the femoral osteotomy surface is within the range of 1-1.5 cm; Constraint index two: the relative position relationship between the femoral stem and the medullary cavity; Evaluation index: the intercept ratio of the line segment composed of the intersection points of the femoral stem x-axis straight line and the femoral stem surface and the medullary cavity surface.

2. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 1, characterized in that, The generated bone key points in S102 include: The center of the femoral head, the medial epicondyle of the femur and the lateral epicondyle of the femur are used to establish a femoral coordinate system; The center of the surgical-side femoral head, the proximal point of the femoral medullary cavity and the distal point of the femoral medullary cavity are used for initial positioning of the femoral stem when placing the femoral stem; The lesser trochanter point is used to calculate the constraint evaluation index after placing the femoral stem.

3. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 1, characterized in that, The initial positioning of each femoral stem in S103 includes: Determining the medullary cavity central axis through the proximal point of the surgical-side femoral medullary cavity and the distal point of the femoral medullary cavity; Placing the femoral stem into the femur so that the femoral stem stem axis coincides with the medullary cavity central axis; Rotating the current femoral stem around the femoral stem stem axis so that the plane where the femoral stem neck and stem are located passes through the center of the femoral head ball; Moving the femoral stem up and down along the femoral stem stem axis so that the extension line of the femoral stem neck axis passes through the center of the femoral head.

4. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 1, characterized in that, The constraint index one: the distance between the lesser trochanter point and the femoral osteotomy surface is calculated by the projection of the connecting line of the intersection points of the lesser trochanter point and the femoral osteotomy surface and the femoral stem neck axis on the normal vector of the femoral osteotomy surface, and the specific process is as follows: Let L represent the point of lesser trochanter, and E represent the intersection point of femoral osteotomy surface and femoral neck axis, then the length of the line segment is represented as , the femoral neck axis is perpendicular to the femoral osteotomy surface, and let the normal vector of the femoral osteotomy surface be , then The projection on is the distance d from the lesser trochanter to the femoral osteotomy surface: 。 5. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 1, characterized in that, The constraint index two: the relative position relationship between the femoral stem and the medullary cavity includes: Two parallel planes are created through the femoral stem origin and the femoral stem bottom end, and the two planes are used to cut the medullary cavity and the femoral stem, wherein the upper plane is the femoral stem XOY plane, and the lower plane passes through the top point of the femoral stem stem bottom end; Judging whether the surface data between the upper and lower planes of the femoral stem is contained in the corresponding medullary cavity surface data, and measuring by calculating the number of points of the femoral stem surface data outside the medullary cavity surface data; If the femoral stem surface data is entirely within the medullary cavity surface data, the number of points of the femoral stem surface data outside the medullary cavity surface data is 0; if the femoral stem surface data is not contained in the medullary cavity surface data, the number of points of the femoral stem surface data outside the medullary cavity surface data is greater than 0.

6. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 1, characterized in that, The evaluation index: the intercept ratio of the line segment composed of the intersection points of the femoral stem x-axis straight line and the femoral stem surface and the medullary cavity surface includes: In the XOY plane of the femoral stem, there are two intersecting straight lines, which are the straight lines passing through the x-axis and y-axis of the femoral stem, respectively. The two intersection points of the straight line passing through the x-axis of the femoral stem and the femoral stem are denoted as and The two intersection points of the straight line passing through the y-axis of the femoral stem and the medullary cavity are denoted as and The ratio is the evaluation index. 。 7. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 6, characterized in that, The three strategies are used to adjust the pose of each femoral stem in S104, including: Adjusting according to the intersection of the x-axis of the femoral stem and the surface data; Adjusting according to the intersection of the y-axis of the femoral stem and the surface data; Adjusting according to the long axis direction of the contour determined by the intersection of the bottom end plane of the femoral stem and the medullary cavity surface.

8. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 7, characterized in that, The adjusting according to the intersection of the x-axis of the femoral stem and the surface data includes: Recall Vector needed for translation in the x-axis direction of the femoral stem: ； The coordinate of the origin of the femoral stem is The coordinate of the bottom of the femoral stem is The height from the origin of the femoral stem to the bottom of the femoral stem is h, and the angle of rotation of the femoral stem around the y-axis is wherein, ； Rotating transformation around the bottom end of the femoral stem with the y-axis of the femoral stem as the rotation axis, specifically including: The femoral stem is translated by a distance of... Translation transformation The rotation angle is Rotational transformation Translational displacement is Translation transformation That is, applying a transformation to the femoral stem. Move the femoral stem to the position that needs adjustment; Adjusting so that the distances of the two femoral stem surfaces in the x-axis direction of the femoral stem to the corresponding side of the medullary cavity are equal, and the part of the femoral stem surface that exceeds the medullary cavity surface is adjusted to the inside of the medullary cavity surface.

9. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 8, characterized in that, The adjusting according to the intersection of the y-axis of the femoral stem and the surface data includes: The two intersection points of the straight line of the femoral stem XOY plane passing through the femoral stem y-axis with the femoral stem are respectively recorded as and The two intersection points with the medullary cavity are respectively recorded as and , and is the vector of the y-axis direction that needs to be translated: ； The angle of rotation of the femoral stem about the x-axis is required to be : ； Rotating transformation around the bottom end of the femoral stem with the x-axis of the femoral stem as the rotation axis, specifically including: The femoral stem is translated by a distance of... Translation transformation The rotation angle is Rotational transformation Translational displacement is Translation transformation That is, applying a transformation to the femoral stem. Move the femoral stem to the position that needs adjustment; Adjusting so that the distances of the two femoral stem surfaces in the y-axis direction of the femoral stem to the corresponding side of the medullary cavity are equal, and the part of the femoral stem surface that exceeds the medullary cavity surface is adjusted to the inside of the medullary cavity surface.

10. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 7, characterized in that, The adjusting according to the long axis direction of the contour determined by the intersection of the bottom end plane of the femoral stem and the medullary cavity surface includes: The intersection line of the bottom end plane of the femoral stem and the medullary cavity surface is approximately elliptical, and the long axis direction is calculated by the minimum circumscribed rectangle; Let the angle between the long axis of the bottom end of the femoral stem and the long axis of the cross section of the medullary cavity be , a rotation transformation of the femoral stem around the z axis by an angle of ; and ​ Adjusting the long axis direction of the bottom end of the femoral stem to be consistent with the long axis direction of the bottom surface of the medullary cavity, so that the part of the femoral stem that exceeds the medullary cavity surface is adjusted back to the inside of the medullary cavity.

11. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 1, characterized in that, The sorting and screening of all the evaluation information in S105 includes: Screening the femoral stem type and pose combination whose distance d from the lesser trochanter to the femoral osteotomy surface meets the constraint or has the smallest distance according to constraint index one; Screening the femoral stem type and pose combination with the least number of points outside the medullary cavity surface according to constraint index two based on the femoral stem type and pose combination screened according to constraint index one; Screening the femoral stem type and pose combination with the largest ratio r according to the evaluation index based on the femoral stem type and pose combination screened according to constraint index two.

12. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 11, characterized in that, The screening of the femoral stem type and pose combination whose distance d from the lesser trochanter to the femoral osteotomy surface meets the constraint or has the smallest distance according to constraint index one includes: Distinguishing the brand series of the femoral stem according to whether the distance d from the lesser trochanter to the femoral osteotomy surface is within the allowable range or outside the allowable range; When there is a femoral stem and pose within the allowable range, all femoral stems and poses within the allowable range enter the screening of constraint index two; When there is no femoral stem and pose within the allowable range, the femoral stem type and pose combination with the smallest distance is selected from outside the allowable range as a candidate to enter the screening of constraint index two.

13. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 11, wherein, The screening of the femoral stem type and pose combination with the least number of points outside the medullary cavity surface according to constraint index two based on the femoral stem type and pose combination screened according to constraint index one includes: The femoral stem type and pose screened according to constraint index one enter the screening of constraint index two, and the number of points of the femoral stem surface outside the medullary cavity surface is arranged in order from small to large according to the brand series of the femoral stem. When the femoral stem is fully contained in the medullary cavity, the femoral stem enters the screening of the evaluation index; When the femoral stem is not fully contained in the medullary cavity, the point number of the femoral stem surface outside the medullary cavity surface is selected as the screening of the evaluation index.

14. The femoral stem prosthesis automatic recommendation method for total hip replacement surgery according to claim 11, wherein, The combination of the femoral stem model and the position selected from the constraint index two is screened again by the evaluation index to select the combination of the femoral stem model and the position with the maximum ratio r. The combination of the femoral stem and the position selected from the constraint index two enters the screening of the evaluation index, and different brand series of femoral stems are sorted according to the ratio r from large to small, and the femoral stem model and the position with the maximum ratio r are selected, so that the best femoral stem model and position are selected.

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