Method and system for pelvic registration in hip revision surgery

Abstract

The present invention relates to the field of medical technology, and specifically to a method and system for pelvic registration in hip revision surgery. The specific method comprises the following steps: (1) obtaining CT tomographic medical imaging data of the pelvis of a patient undergoing hip revision surgery; (2) constructing a digital three-dimensional model using the obtained CT data; (3) low-precision registration; (4) obtaining low-precision registration information and high-precision registration information of all patients who have undergone revision surgery; and (5) matching the low-precision registration information of this patient with the low-precision registration information of each patient who has undergone revision surgery. The present invention determines the selection criteria of bony landmark points and bone surface points in hip revision surgery, and the method searches for the registration information corresponding to the first few patients with the highest similarity based on the digital three-dimensional model of the pelvis, determines the preferred registration area, and enables the surgeon to have a foreknowledge of the bony landmark points and bone surface points required for pelvic registration before or during hip revision surgery.

Description

Technical Field

[0001] The present invention relates to the field of medical technology, and in particular to a method and system for pelvic registration in hip joint revision surgery. Background Art

[0002] Although artificial joint replacement is now very mature, a large number of patients who have undergone primary joint replacement still need revision surgery due to many reasons such as prosthesis loosening (bacterial / aseptic), periprosthetic fracture, prosthesis dislocation, etc.

[0003] Due to the many reasons for revision surgery and the complexity of the condition, performing joint revision surgery requires extremely high surgical skills and rich surgical experience. Even so, the satisfaction rate of revision surgery is still relatively low. Reasonable filling of the defect is an important step in joint revision surgery. With the development of 3D printing technology, patches of various shapes have begun to play an important role, personalized prostheses for patients have also begun to appear, and revision surgery has also made certain progress. However, one problem that has never been solved in revision surgery is how to accurately place the patch or prosthesis. Even for customized prostheses, there is still a high probability that they will not fit in or be placed in the wrong position.

[0004] A patent proposes a navigation system for orthopedic revision surgery, which can solve the navigation of tools and prostheses throughout the entire process of orthopedic revision surgery. In the above-mentioned surgical operation, an important step is to match the digital 3D model of the bone with the actual bone, that is, to obtain the position and posture of the actual bone through the positioning device, and to establish a series of transformations so that the position and posture of the digital 3D model can be expressed by the position and posture of the actual bone through these transformations. This process is called registration, and the actual effect is equivalent to aligning the digital 3D model with the actual bone. Registration has a great impact on the accuracy of the operation.

[0005] The conventional registration process includes: low-precision registration, high-precision registration and registration confirmation. Low-precision registration is also called point registration, which is generally achieved by selecting matching bony markers on the digital 3D model and the actual bone. High-precision registration is also called surface registration, which is actually achieved by the positioning system continuously collecting the positions of multiple actual bone surface points, and automatically calculating the positions of the points on the digital 3D model that match them, by fine-tuning the alignment of the digital 3D model with the actual bone. In the conventional registration process, accurate collection of actual bone surface points is particularly important.

[0006] The difficulty of pelvic registration during hip revision surgery lies in the fact that there may be differences between the digital three-dimensional model of the pelvis and the actual bones. It is necessary to determine accurate bony landmarks and bone surface points to ensure the smooth implementation of the registration process. Summary of the invention

[0007] The object of the present invention is to provide a method for pelvic registration in hip revision surgery, comprising the following steps:

[0008] Acquire computerized tomography image data of the current patient's pelvis;

[0009] constructing a digital three-dimensional model of the current patient using the acquired CT image data;

[0010] The prosthesis is registered with the bone with low precision;

[0011] Obtain low-precision registration information and high-precision registration information for patients who have undergone revision surgery;

[0012] Matching the low-precision registration information of the current patient with the low-precision registration information of each patient who has undergone revision surgery one by one, and recording the degree of matching with each patient and the high-precision registration information of the current patient and the patients who have undergone revision surgery;

[0013] Perform a global comparison of the matching results of patients who have undergone revision surgery to obtain the most similar patients who have undergone revision surgery and the high-precision registration information corresponding to the patients who have undergone revision surgery;

[0014] Based on the most similar patient who has undergone revision surgery, the high-precision registration information is counted and voted, the high-precision registration information of the current patient is predicted, and the preferred registration area is determined;

[0015] Performing high-precision registration of the digital three-dimensional model of the bone with the actual bone in the registration preferred area;

[0016] Save the registration results.

[0017] Optionally, the medical image data in the step is two-dimensional medical image DICOM data.

[0018] Optionally, in the step, the digital three-dimensional model is constructed by operating DICOM data into a digital three-dimensional model through medical image processing software.

[0019] Optionally, in the step, the digital three-dimensional model of the bone is matched with the actual bone to obtain a first registration result.

[0020] Optionally, the registration information obtained in the step may be the absolute coordinates of the selected point in the CT original coordinate system, or the relative coordinates of the selected point in the bone anatomical coordinate system.

[0021] Optionally, the low-precision registration in the step adopts a three-point registration method as an example, and the three points selected for registration are defined with reference to the anatomical positions of the human body, namely, a front point, a rear point, and an upper point;

[0022] The specific matching method is as follows:

[0023] 1) Compare the front point-back point connection line of the low-precision registration three points of this patient with the front point-back point connection line of the low-precision registration three points of each patient who has undergone revision surgery on the same side before treatment, calculate the scaling coefficient that makes the two equal in length, and scale the 3D model of this patient according to the coefficient to make the two connection lines equal in length;

[0024] 2) The anterior-posterior line of this patient is aligned with the anterior-posterior line of each patient who has undergone revision surgery, and the anterior-posterior direction is consistent;

[0025] 3) The plane determined by the anterior point-posterior point-upper point of this patient is made coplanar with the plane determined by the anterior point-posterior point-upper point of each patient who has undergone revision surgery, so that the coordinate system of the two digital three-dimensional models is the same;

[0026] 4) Extract the upper point correlation parameters of the two to characterize the model;

[0027] 5) Use mean square error, Camberra distance, and similarity calculation methods to calculate the above points and give quantitative matching results.

[0028] Optionally, the step selects points within the registration preferred area, performs a second registration using a conventional registration method, matches the digital three-dimensional model of the bone with the actual bone, and achieves high-precision registration.

[0029] Optionally, the step of saving the registration results and forming a database is as follows: the coordinates of the points selected for the initial and high-precision registration are saved to form a database. This database can provide a data source for the data of patients who have undergone revision surgery.

[0030] Optionally, also include:

[0031] An acquisition module, used to acquire a digital three-dimensional model of the pelvis of a patient undergoing hip revision surgery;

[0032] A display module, used to display the digital tool and the digital three-dimensional model, so as to present the actual position and posture of the tool and the actual skeleton in real time;

[0033] The region generation module is used to complete the step-to-step data acquisition, matching, and analysis, and generate the registration preferred region;

[0034] The data module is used to save the registration results and form a database.

[0035] Optionally, a system for pelvic registration in hip revision surgery, characterized in that it includes a navigation system for orthopedic revision surgery, the navigation system comprising:

[0036] The user identification is at least one of an infrared light ball array, a QR code, or a stripe sequence;

[0037] A positioning module, used to generate positioning information of the patient's bones and surgical tools;

[0038] A communication module, used to process the positioning information and convert the positioning information into data for transmission;

[0039] A storage module, used for storing underlying data, wherein the underlying data includes initial information of the tool and data required for implementing intraoperative navigation;

[0040] A data processing module, used to process the underlying data and the processed positioning information to generate rendering data for dynamic visualization of tools, bones, and prostheses;

[0041] A display module displays the rendering data.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention determines the selection criteria of bony landmark points and bone surface points in hip revision surgery. The method is based on the digital three-dimensional model of the pelvis, searches for the registration information corresponding to the first few patients with the highest similarity, and determines the preferred registration area, so that the surgeon can predict the bony landmark points and bone surface points required for pelvic registration before or during hip revision surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a structural block diagram of the navigation system of the present invention;

[0045] Figure 2 It is an implementation diagram of the renovation navigation process of the present invention;

[0046] Figure 3 is a flow chart of the method of the present invention;

[0047] Figure 4 It is a schematic diagram of the three-point registration of the acetabulum of the present invention;

[0048] Figure 5 A flow chart of the method for registering the preferred area of ​​the present invention;

[0049] Figure 6 This is a system diagram of the present invention.

[0050] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0052] See also Figure 1-Figure 6 The present invention provides a method for pelvic registration in hip joint revision surgery, the steps of which are as follows:

[0053] (1) CT scan medical imaging data, see attached Figure 2 In step 301, CT tomography medical image data of the pelvis of a patient undergoing hip revision surgery is obtained, and the medical image data is two-dimensional medical image DICOM data;

[0054] (2) Use the acquired CT data to construct a digital 3D model, see Appendix Figure 2 Step 302. Since the revision surgery patient has undergone hip replacement surgery, the two-dimensional medical image DICOM data may contain implanted prostheses (to be removed in the revision surgery) in addition to pelvic information, and the digital three-dimensional model is constructed from the DICOM data into a digital three-dimensional model through medical image processing software:

[0055] A. Presence of implanted prostheses: The metal artifacts produced by the prosthesis will have a certain impact on the construction of the digital 3D model (the digital 3D model constructed in the area affected by the artifact will have a large deviation from the actual bone). No artifact removal or other processing will be performed here.

[0056] B. There is no implanted prosthesis (e.g., the prosthesis has been removed by surgery before revision surgery): some areas on the surface of the model are discontinuous or not smooth;

[0057] (3) Low-precision registration see attached Figure 2 In step 303, a point in the area around the acetabulum that is not affected by the original implanted prosthesis is selected, such as Figure 4 As shown in the figure, select the three points "1", "2" and "3" in the figure, use the three-point registration method to perform the first registration, match the digital three-dimensional model of the bone with the actual bone, and get the first registration result.

[0058] Determine the preferred area for registration, see attached Figure 2 In step 304, the method for determining the registration preferred area is as follows: (4)-(7)

[0059] (4) Obtain low-precision registration information and high-precision registration information for all patients who have undergone revision surgery. The operation steps of high-precision registration can refer to step (3); the operation steps of high-precision registration can refer to step (3) (changing three-point registration to surface registration, etc.), which can be implemented based on conventional methods such as ICP algorithm. The obtained registration information can be the absolute coordinates of the selected point in the original CT coordinate system, or the relative coordinates of the selected point in the skeletal anatomical coordinate system;

[0060] (5) The low-precision registration information of this patient is matched one by one with the low-precision registration information of each patient who has undergone revision surgery, and the matching degree with each group of patients and their high-precision registration information are recorded. Taking the three-point registration method of low-precision registration as an example, the three points selected for registration are defined as the front point (close to the front side of the human body), the back point (close to the back side of the human body), and the upper point (close to the upper side of the human body) with reference to the anatomical position of the human body. The specific method of matching the digital three-dimensional model of the bone with the actual bone is as follows:

[0061] 1) Compare the front point-back point connection line of the low-precision registration three points of this patient with the front point-back point connection line of the low-precision registration three points of each patient who has undergone revision surgery on the same side (left and right sides must be consistent) before treatment, calculate the scaling coefficient that makes the two equal in length, and scale the 3D model of this patient according to the coefficient to make the two lines equal in length;

[0062] 2) The anterior-posterior line of this patient is aligned with the anterior-posterior line of each patient who has undergone revision surgery, and the anterior-posterior direction is consistent;

[0063] 3) Make the plane determined by the front point-back point-upper point of this patient coplanar with the plane determined by the front point-back point-upper point of each patient who has undergone revision surgery. At this point, the coordinate system of the two digital three-dimensional models is the same;

[0064] 4) Extract the upper point correlation parameters of the two to characterize the model;

[0065] 5) Use similarity calculation methods such as mean square error and Camberra distance to calculate the upper point (such as calculating the similarity of the vector connection line between the previous point and the upper point, or the similarity of the vector connection line between the next point and the upper point) to give a quantitative matching result;

[0066] (6) Globally compare the matching results with all patients who have undergone revision surgery to obtain the most similar patients and their corresponding high-precision registration information;

[0067] (7) Based on these most similar patients, their high-precision registration information is counted and voted, so as to make a prediction on the high-precision registration information of this patient and determine the optimal registration area;

[0068] In summary, a global comparison is made on the matching results of all patients who have undergone revision surgery to obtain the most similar patients and their corresponding high-precision registration information; based on these most similar patients, their high-precision registration information is counted and voted. At this time, the high-precision registration information obtained is generally a point set composed of high-precision registration selected points.

[0069] The point set is post-processed so that the selected points are within the touchable area exposed during surgery. The post-processing process of the point set is as follows:

[0070] 1) Mapping the obtained point set onto the digital three-dimensional model of the patient to form a mapping point set;

[0071] 2) Fit the front point, the back point and the top point into a circle (the circle can be stretched into a cylindrical surface along the normal of the circular plane), and use this circle (or cylindrical surface) as the boundary of the point set screening;

[0072] 3) Determine the relative position relationship between the mapping point set and the boundary, define the points inside the circle (or cylinder) as valid points, and the points outside the circle as invalid points. The area surrounded by the outermost points of all valid points is defined as the preferred registration area.

[0073] (8) Perform high-precision registration in the preferred area. Figure 2 In step 305, points in the registration preferred area are specifically selected, and a second registration is performed using a conventional registration method to match the digital three-dimensional model of the bone with the actual bone to achieve high-precision registration;

[0074] (9) The registration results are saved and a database is formed, and the coordinates of the points selected for the initial and high-precision registration are saved to form a database. This database can provide a data source for the data of patients who have undergone revision surgery in step (5).

[0075] like Figure 1 As shown, the system of the present invention comprises:

[0076] The doctor side / patient side is an infrared light ball array (active / passive), or a QR code, or a stripe sequence, as well as other characteristic marking points with the same technical principles.

[0077] The positioning module is a detection device used to detect and identify array patterns. It can convert the identified patterns into three-dimensional spatial coordinates for positioning and tracking of patient bones and surgical tools.

[0078] The communication module is used to process the data of the positioning module and output the data to the data processing module.

[0079] The data processing module reads the underlying data in the storage module, including tool models, planning files and other data required for navigation, and accepts the output of the communication module. After processing all the data, it generates rendering picture data and transmits it to the display module.

[0080] The display module dynamically visualizes the tools, bones, and prostheses, and quantitatively displays the implantation position and angle.

[0081] Preoperative planning uses the patient's skeletal model, and the images used for skeletal inversion include one or more modalities such as CT and MRI.

[0082] Renovation planning can be done independently by doctors or remotely with the assistance of engineers.

[0083] Planning includes filling of bone defects, using universal patches or personalized designs for the patient, and obtained through machining or 3D printing.

[0084] Planning includes restoration of the patient's own anatomy and mechanical structure, specifically, when used for hip revision, restoration of the center of rotation, leg length, and offset distance.

[0085] The planned files include patient bone model, prosthesis model, tool model, patch model, customized prosthesis model, prosthesis six-degree-of-freedom information, cup coverage, anatomical key points and all other data needed for intraoperative navigation implementation.

[0086] Tools that can be used during the operation include, but are not limited to, rotating rod structures.

[0087] The methods of skeleton registration include but are not limited to three-point registration and surface registration, and the algorithms used include but are not limited to ICP algorithm.

[0088] Bone registration can be performed after removing the original prosthesis. If the preoperative artifact is severe, the original prosthesis can also be registered with the bone before removing the prosthesis.

[0089] like Figure 6 As shown, the system of the present invention also includes:

[0090] (1) Acquisition module for 3D reconstruction, see Appendix for details Figure 2 Step 201 is used to obtain a digital three-dimensional model of the pelvis of a patient undergoing hip revision surgery;

[0091] (2) Display module, used to display digital tools and digital 3D models, so as to present the actual position of tools and actual bones in real time for customizing the frame. See Appendix for details. Figure 2 In step 202, a general patch can also be used. See the attached Figure 2 In step 203,

[0092] (3) a region generation module, used to complete the data acquisition, matching, and analysis of steps (4) to (7), and generate a registration preferred region;

[0093] Both custom prostheses and universal patches can complete bone registration. Figure 2 In step 204,

[0094] (4) Data module, used to save the registration results and form a database to achieve bone registration. See Appendix for details. Figure 2 In step 205,.

[0095] Bone preparation, see Appendix Figure 2 In step 206, the bone surface is mainly processed, irregular bone spurs are removed according to the plan or the actual situation during the operation, and irregular cavities or defects are processed into regular arc surfaces to facilitate the subsequent implantation of prostheses or patches.

[0096] Bone surface processing tools include but are not limited to: flat saws, curved saws, lasers, water jets, ultrasonic vibrations and burs.

[0097] Bone surface processing tools can be positioned and tracked in real time during surgery, and the tool accuracy can be verified through the processing features set in advance on the tool.

[0098] The bone surface processing process can be displayed dynamically. When the execution end of the processing tool contacts the bone surface, the bone model can display the status after cutting in real time. In case of over-cutting, the software can give prompts or alarms.

[0099] In some embodiments, the revision ultimately results in fixation of the prosthesis or patch with screws.

[0100] In some embodiments, screw holes are usually pre-drilled before screw implantation, i.e., pre-drilled screw holes. Figure 2 Step 207.

[0101] You can use a straight drill or a universal drill to drill screw holes.

[0102] In some embodiments, when a universal drill is used, the direction of the hole is determined by a flexible drill guide.

[0103] In some embodiments, when a universal drill is used, the universal drill can provide a plurality of different length specifications, and a mechanical limit is used to limit the drilling depth.

[0104] In some embodiments, before using a soft drill to drill a hole, a soft drill guide can be placed on the bone surface, and the software will display a virtual hole on the virtual bone to measure the drilling location and drilling depth.

[0105] The patch holder is locked with the patch by means of threads or other quick-connect methods, and the connection relationship is unique and fixed.

[0106] The patch model can be selected, and the selected patch model will be changed in real time in the software display.

[0107] In some embodiments, the patch is implanted, as described in the attached Figure 2 In step 208, if a customized patch or prosthesis is used, a unique interface that is compatible with the patch holder should be designed when the prosthesis is designed.

[0108] Screw fixation, see attached Figure 2 In step 209, the screw holder can be positioned and tracked in real time, and the position of the screw is reflected by the screw holder.

[0109] In some embodiments, when implanting a patch or prosthesis, if the shape of the cavity or defect does not match the prosthesis and cannot be implanted, the doctor can return to the bone preparation page.

[0110] In some embodiments, depending on the surgical requirements, the doctor can switch between multiple steps such as bone preparation, pre-drilling of screw holes, patch implantation, and screw fixation.

[0111] Prosthesis implantation, see attached Figure 2 After the patient's joint is repositioned in step 210, the implantation of the prosthesis can be evaluated by picking up the anatomical key points on the patient's bone or prosthesis. In particular, when performing hip revision, the main evaluations include leg length, offset distance, rotation center, position of the prosthesis or patch, etc.

[0112] The software can generate a report on the surgical results based on the surgical implementation status for postoperative evaluation.

[0113] The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the scope of protection determined by the claims submitted for the present invention.

Claims

1. A method for pelvic registration in hip revision surgery, characterized in that: The steps include: (1) obtaining computerized tomography image data of the patient's pelvis; (2) constructing a digital three-dimensional model of the current patient using the acquired computed tomography image data; (3) Low-precision registration, matching the digital 3D model of the skeleton with the actual skeleton to obtain the first registration result; (4) Obtain low-precision registration information and high-precision registration information for patients who have undergone revision surgery; (5) matching the low-precision registration information of the current patient with the low-precision registration information of each patient who has undergone revision surgery, and recording the degree of matching with each patient and the high-precision registration information of the current patient and the patients who have undergone revision surgery; (6) globally comparing the matching results of patients who have undergone revision surgery to obtain the most similar patients who have undergone revision surgery and the high-precision registration information corresponding to the patients who have undergone revision surgery; (7) based on the most similar patient who has undergone revision surgery, the high-precision registration information is counted and voted, the high-precision registration information of the current patient is predicted, and the preferred registration area is determined; and (8) Performing high-precision registration of the digital three-dimensional model of the bone with the actual bone within the preferred registration area.

2. The method for pelvic registration in hip revision surgery according to claim 1, characterized in that: The medical image data in step (1) is two-dimensional medical image DICOM data.

3. The method for pelvic registration in hip revision surgery according to claim 1, characterized in that: In the step (2), the digital three-dimensional model is constructed by operating the DICOM data into a digital three-dimensional model through medical image processing software.

4. The method for pelvic registration in hip revision surgery according to claim 1, characterized in that: The registration information obtained in step (4) according to step (3) may be the absolute coordinates of the selected point in the original coordinate system of the computed tomography scan, or the relative coordinates of the selected point in the skeletal anatomical coordinate system.

5. The method for pelvic registration in hip revision surgery according to claim 1, characterized in that: The low-precision registration in step (5) adopts a three-point registration method, and the three points selected for registration are defined with reference to the anatomical positions of the human body, namely, the front point, the back point, and the upper point; The specific matching method is as follows: 1) Compare the front point-back point connection line of the low-precision registration three points of this patient with the front point-back point connection line of the low-precision registration three points of each patient who has undergone revision surgery on the same side before treatment, calculate the scaling coefficient that makes the two equal in length, and scale the 3D model of this patient according to the coefficient to make the two connection lines equal in length; 2) The anterior-posterior line of this patient is aligned with the anterior-posterior line of each patient who has undergone revision surgery, and the anterior-posterior direction is consistent; 3) The plane determined by the anterior point-posterior point-upper point of this patient is made coplanar with the plane determined by the anterior point-posterior point-upper point of each patient who has undergone revision surgery, so that the coordinate system of the two digital three-dimensional models is the same; 4) Extract the upper point correlation parameters of the two to characterize the model; 5) Use mean square error, Camberra distance, and similarity calculation methods to calculate the above points and give quantitative matching results.

6. The method for pelvic registration in hip revision surgery according to claim 1, characterized in that: In the step (8), points in the registration preferred area are selected, and a second registration is performed using a conventional registration method to match the digital three-dimensional model of the bone with the actual bone to achieve high-precision registration.

7. The method for pelvic registration in hip revision surgery according to claim 1, characterized in that: The registration results are saved and a database is formed. Specifically, the coordinates of the points selected by the initial and high-precision registration are saved to form a database. This database can provide a data source for the data of patients who have undergone revision surgery in step (5).

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