Design method of acetabulum rebuilding guide bracket based on image modeling

Abstract

The invention provides a parameter design method for an acetabulum rebuilding guide support based on image modeling, and belongs to the field of medical instruments, and the method comprises the steps: building an acetabulum coordinate system, and carrying out the geometric parameter extraction of a medical image on a bone defect region; defining abduction angles, front inclination angles and vertical upward moving heights of outer cups in the plurality of bone trabecula metal acetabular cups, and coupling to obtain a finite parameter combination; respectively calculating the contact volume ratio eta of the bone trabecula metal acetabular cup and the bone defect area of each group of data and the distance Doff from the rotation center of the outer cup to the healthy rotation center; screening according to the numerical values of eta and Doff to obtain a group of optimal parameters; and designing the guide bracket for the outer cup according to the optimal parameters. A simple, efficient and accurate digital solution is provided for Paprosky III-type acetabular defect revision, the core geometric quantification method and guide support design can be expanded to other complex bone defect repair, and the Paprosky III-type acetabular defect revision method has remarkable clinical application value and technical perspectiveness.

Description

Technical Field

[0001] The present invention relates to the technical field of medical device design, and in particular to a design method for an acetabulum revision guide bracket based on image modeling. Background Art

[0002] Paprosky type III acetabular defect is one of the most complex conditions in hip revision surgery. Its core characteristics are pelvic discontinuity, extensive destruction of the acetabular wall, and significant upward shift of the center of rotation. It requires reconstruction of the acetabular structure through a trabecular metal acetabular cup (inner cage) combined with an outer cup.

[0003] Traditional surgery has the following core problems:

[0004] Parameter determination relies on subjective experience: doctors determine the acetabular cup implantation angle (abduction angle, anteversion angle) and the position of the rotation center by visual observation or a simple protractor. There is a lack of quantitative standards for contact volume and rotation center deviation, resulting in a prosthesis loosening rate as high as 15%-20% and a postoperative lower limb length inequality rate of 25%.

[0005] Insufficient anatomical adaptability: Universal guide tools cannot accurately fit the shape of individual bone defects, especially in cases of pelvic discontinuity (type III-B). Repeated trial mold adjustments are required during surgery, resulting in long surgery time (average 135 minutes) and a high risk of infection (4%-6%).

[0006] The mechanical support assessment is vague: there is a lack of quantitative analysis of the contact area between the acetabular cup and the host bone. Insufficient contact volume (<50%) often leads to early bone graft absorption or prosthesis micromotion, and poor long-term imaging stability.

[0007] The existing technology has the following problems:

[0008] Manual operation: Visual positioning is performed through bony landmarks such as the anterior superior iliac spine and ischial tuberosity. The contact volume can only be roughly estimated (error > 20%), and the deviation of the rotation center is more than ±3mm, which significantly increases the risk of prosthesis loosening after surgery.

[0009] Universal guide: A fixed angle is preset (such as an abduction angle of 40°), but the pelvic inclination angle of different patients can vary by up to ±10°, resulting in a deviation of ±8° in the actual implantation angle, which cannot meet individual needs.

[0010] Deficiencies of existing quantitative methods: There is a lack of standardized contact volume measurement methods, and the clinical threshold of "contact volume accounting for more than 50% of the bone defect volume" has not been defined, resulting in failure of some cases due to insufficient support.

[0011] The reduction of the rotation center relies on empirical formulas such as "15 mm above the midpoint of the teardrop line" without considering the patient's specific bone defect location, resulting in insufficient anatomical reduction accuracy. Summary of the Invention

[0012] To address the above issues, the present invention provides a design method for an acetabular revision guide bracket based on image modeling. Through three-dimensional modeling of medical images, the intersection volume between the acetabular cup and the bone defect (contact volume ratio ≥50%) and the deviation of the rotation center distance (≤8mm) are directly measured. The empirical parameter determination is converted into quantifiable and verifiable geometric index control to ensure the accuracy and standardization of implant parameters. Specifically, the method includes:

[0013] A design method for an acetabulum revision guide bracket based on image modeling, comprising:

[0014] Establish the acetabulum coordinate system and extract the geometric parameters of the bone defect area from medical images;

[0015] The abduction angle, anteversion angle and vertical displacement height of the outer cup of multiple trabecular metal acetabular cups are defined, and a finite parameter combination is obtained by coupling;

[0016] Calculate the contact volume ratio η between the trabecular metal acetabular cup and the bone defect area and the distance D from the rotation center of the outer cup of the trabecular metal acetabular cup to the healthy rotation center for each data set within the finite parameter combination. offse ;

[0017] According to η and D offse A set of optimal parameters is obtained by numerical screening;

[0018] A guide bracket for installing the middle and outer cups of trabecular metal acetabular cups was designed according to the optimal parameters.

[0019] Optionally, establishing the acetabulum coordinate system includes:

[0020] With the teardrop center of the healthy side as the origin O, define the X axis, Y axis and Z axis, and mark the rotation center C of the healthy acetabulum. normal ;

[0021] Among them, C normal The coordinates are (x0, y0, z0).

[0022] Optionally, the defining of the abduction angle, anteversion angle, and vertical upward height of the outer cup of the multiple trabecular metal acetabular cups and coupling to obtain a finite parameter combination includes:

[0023] The abduction angles of the outer cup in multiple trabecular metal acetabular cups were defined as 35°, 40°, and 45°.

[0024] The anteversion angles of the external cup of multiple trabecular metal acetabular cups were defined as 10°, 15°, and 20°;

[0025] Define the vertical upward height as 0mm, 5mm, 10mm and 15mm;

[0026] The coupling results in a finite parameter combination, wherein the number of parameter groups in the finite parameter combination is 36.

[0027] Optionally, the formula for calculating the contact volume ratio η between the trabecular metal acetabular cup and the bone defect area for each set of data in the finite parameter combination is formula (1):

[0028] η=(V defect / V contact )×100%; (1)

[0029] V defect is the volume of bone defect area;

[0030] V contact It is the volume of the intersection of the trabecular metal acetabular cup and the bone defect area.

[0031] Optionally, the distance D between the rotation center of the outer cup of the trabecular metal acetabular cup and the healthy rotation center is offse The formula is formula (2):

[0032] ; (3)

[0033] The coordinates of the rotation center of the outer cup of the trabecular metal acetabulum in the current parameter group are (x, y, z).

[0034] Optionally, the method according to η and D offse The optimal parameters obtained by numerical screening include:

[0035] Screen out η≥50% and D offse Parameter group ≤8mm;

[0036] If the number of parameter groups screened is greater than 1, the parameter group with the largest η is selected. When the number of parameter groups with the largest η is 1, the parameter group with the largest η is the optimal parameter. If the number of parameter groups with the largest η is greater than 1, D is selected from multiple parameter groups with the largest η. offse The smallest parameter group is the optimal parameter;

[0037] If the number of the selected parameter groups is 1, the selected parameter group is the optimal parameter.

[0038] Optionally, the guide bracket includes: an iliac wing fitting plate, an ischial ramus guide block, an anteversion angle positioning plate and an abduction angle positioning plate;

[0039] The iliac wing fitting plate fits the surface structure of the ilium, and the iliac wing fitting plate is installed on the ilium through positioning pins;

[0040] The ischial ramus guide block is in contact with the surface structure of the ischial free bone block, and the ischial ramus guide block is installed on the ischial free bone block through a positioning pin;

[0041] The anteversion angle positioning plate is semicircular, and a rotation axis is provided at each end of the diameter of the anteversion angle positioning plate. The rotation axis at each end of the anteversion angle positioning plate is respectively mounted on the mounting column on the iliac wing fitting plate and the mounting column on the ischial support guide block;

[0042] The abduction angle positioning plate and the anteversion angle positioning plate are integrally arranged. The abduction angle positioning plate is semicircular, and the straight edge of the abduction angle positioning plate is perpendicular to the anteversion angle positioning plate. Spatially, the abduction angle positioning plate and the anteversion angle positioning plate are in a spherical space with the same diameter.

[0043] Optionally, an abduction angle dial is provided on one end of the anteversion angle positioning plate facing the iliac wing fitting plate;

[0044] The abduction angle of the abduction angle positioning plate is changed by rotating the anteversion angle scale; wherein, according to the three angles of 35°, 40° and 45° marked on the abduction angle scale, the abduction angle of the outer cup of the trabecular metal acetabular cup meets the abduction angle within the optimal parameters.

[0045] Optionally, the anteversion angle fixing plate is aligned with the sagittal plane of the pelvis.

[0046] Optionally, the guide bracket designed according to the optimal parameters for mounting the inner and outer cups of the trabecular metal acetabular cup comprises:

[0047] According to the abduction angle within the optimal parameters, the anteversion angle fixing plate is controlled to rotate around the straight edge of the anteversion angle fixing plate according to the abduction angle scale to a target angle;

[0048] Prefabricate the inclined surface of the anteversion angle positioning plate according to the anteversion angle within the optimal parameters so that the anteversion angle positioning plate fits the sagittal plane of the pelvis;

[0049] The rotation center of the trabecular metal acetabular cup is determined according to the height of the vertical upward movement within the optimal parameters. The rotation center of the trabecular metal acetabular cup is the intersection of the straight edges of the anteversion angle fixing plate and the abduction angle fixing plate.

[0050] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0051] This invention provides a simple, efficient, and precise digital solution for the revision of Paprosky III acetabular defects. Its core geometric quantification method and guide bracket design can be extended to the repair of other complex bone defects, and has significant clinical application value and technical foresight.

[0052] For the first time, the dual-metric control of implant parameters using contact volume ratio (≥50%) and rotation center deviation (≤8mm) was proposed, replacing traditional empirical judgment and transforming empirical surgery into a measurable, verifiable, standardized procedure. 2. Predefined commonly used clinical angle and height ranges replace complex algorithms with limited combination traversal, significantly reducing computational complexity while ensuring accuracy, making it suitable for rapid clinical application. The guide stent directly maps image measurement parameters, forming a three-dimensional positioning system using positioning pins, angle slots, and spatial indicators to achieve precise transmission of "image data-stent parameters-intraoperative implantation." For the first time, medical image processing and optimization algorithms are combined to construct a multi-dimensional parameter calculation system based on "image-mechanics-geometry." Customized based on the patient's specific bone structure and mechanical requirements, the guide stent is designed to directly map to the dual metrics. Preset angle ranges and positioning references enable precise implantation without the need for complex algorithms.

[0053] This solves the "one-size-fits-all" adaptation challenges of traditional general-purpose tools. Through the dual guarantees of hardware limits and software algorithms, a closed-loop precision repair system is achieved, enabling "preoperative simulation, intraoperative control, and postoperative prediction." BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1 Schematic diagram of the installation positions of the inner cup and the outer cup of the trabecular metal acetabular cup in the patient's body in this method;

[0056] Figure 2 Schematic diagram of the structure of the guide bracket used for installing the inner and outer cups of the trabecular metal acetabular cup in this method;

[0057] Figure 3 This is a schematic diagram of the structure of the abduction angle scale groove of the guide bracket in this method;

[0058] Figure 4 is the acetabulum coordinate system established in this method;

[0059] Figure 5 The rotation center C of the inner cup, outer cup and healthy acetabulum on the acetabulum coordinate system normal Schematic diagram of the location;

[0060] Figure 6 This is an image of the inner and outer cups of the trabecular metal acetabular cup in a patient's body for practical application;

[0061] Figure 7This is an image diagram of the installation of the outer cup in one embodiment of the present method in actual application. DETAILED DESCRIPTION

[0062] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments 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 described 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.

[0063] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meaning understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "an" or "the" do not indicate a quantity limitation, but rather indicate the presence of at least one. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0064] Based on the shortcomings of the existing technology, this embodiment provides a design method for an acetabulum revision guide bracket based on image modeling through creative experiments. The specific contents are as follows:

[0065] like Figures 1 to 7 As shown, a design method for an acetabular revision guide bracket based on image modeling includes:

[0066] S1. Establishing the acetabulum coordinate system and extracting geometric parameters of the bone defect area from medical images;

[0067] S2, defining the abduction angle, anteversion angle, and vertical displacement height of the outer cup of multiple trabecular metal acetabular cups, and coupling them to obtain a finite parameter combination;

[0068] S3. Calculate the contact volume ratio η between the trabecular metal acetabular cup and the bone defect area and the distance D from the rotation center of the outer cup of the trabecular metal acetabular cup to the healthy rotation center for each data set within the finite parameter combination. offse ;

[0069] S4, according to η and D offse A set of optimal parameters is obtained by numerical screening;

[0070] S5. Design a guide bracket for installing the inner and outer cups of the trabecular metal acetabular cup based on the optimal parameters.

[0071] A specific implementation method, S1, establishes an acetabulum coordinate system and extracts geometric parameters of the bone defect area from medical images; specifically includes:

[0072] With the teardrop center of the healthy side as the origin O, define the X axis, Y axis and Z axis, and mark the rotation center C of the healthy acetabulum. normal ; C normal The coordinates of the acetabulum are (x0, y0, z0). Specifically, with the center of the teardrop on the healthy side as the origin O, define the X-axis (left and right), Y-axis (front and back), and Z-axis (vertical). Mark the rotation center of the healthy acetabulum Cnormal(x0, y0, z0) (determined by fitting the acetabular rim vertex and the femoral head sphere center).

[0073] Perform threshold segmentation on the CT image to extract the bone defect region Vdefect and calculate its volume and boundary coordinates. Import the 3D parametric model Ccage of the trabecular metal acetabular cup (inner cage). Import the 3D parametric model Couter of the trabecular metal acetabular cup (outer cup), and define its geometric center as the implant rotation center Couter(x, y, z).

[0074] A specific implementation method, S2, defines the abduction angle, anteversion angle and vertical upward height of the outer cup in multiple trabecular metal acetabular cups, and couples them to obtain a finite parameter combination; the trabecular metal acetabular cup includes an inner cup and an outer cup. Generally, the inner cup is directly put in and fixed according to needs and technical experience, and then the outer cup is installed in the inner cup. It is necessary to adjust the installation angle of the outer cup so that the outer cup + inner cup can cover more bone defect areas.

[0075] This step specifically includes:

[0076] The abduction angles of the outer cup in multiple trabecular metal acetabular cups were defined as 35°, 40°, and 45°.

[0077] The anteversion angles of the external cup of multiple trabecular metal acetabular cups were defined as 10°, 15°, and 20°;

[0078] The vertical upward movement height is defined as 0mm, 5mm, 10mm and 15mm; the vertical upward movement height is the height relative to the original position, and the initial position is selected as the empirical position.

[0079] The coupling results in a finite parameter combination, wherein the number of parameter groups in the finite parameter combination is 36.

[0080] For example:

[0081] Parameter group 1: abduction angle = 35°; anteversion angle = 10°; straight upward height = 0 mm;

[0082] Parameter group 2: abduction angle = 40°; anteversion angle = 10°; straight upward height = 0 mm;

[0083] Parameter group 3: abduction angle = 45°; anteversion angle = 10°; straight upward height = 0 mm;

[0084] Parameter group 4: abduction angle = 35°; anteversion angle = 15°; straight upward height = 0mm;

[0085] Parameter group 5: abduction angle = 35°; anteversion angle = 45°; straight upward height = 0 mm; ... until parameter group 36, which is equivalent to the permutation and combination of the above parameters to obtain a finite parameter combination.

[0086] In a specific embodiment, S3, the contact volume ratio η between the trabecular metal acetabular cup and the bone defect area and the distance D from the rotation center of the outer cup of the trabecular metal acetabular cup to the healthy rotation center are calculated for each set of data in the finite parameter combination. offse ; Specifically include:

[0087] The formula for calculating the contact volume ratio η between the trabecular metal acetabular cup and the bone defect area for each set of data in the finite parameter combination is formula (1):

[0088] η=(V defect / V contact )×100%; (1)

[0089] V defect is the volume of bone defect area;

[0090] V contact It is the volume of the intersection of the trabecular metal acetabular cup and the bone defect area.

[0091] In formula (1), a Boolean intersection operation is performed on the acetabular cup model and the bone defect model using three-dimensional modeling software (such as Mimics) to directly obtain the intersection volume and calculate the contact volume ratio η. Clinically, η ≥ 50% is generally required to ensure sufficient bone support area.

[0092] The distance D from the rotation center of the outer cup of the trabecular metal acetabular cup to the healthy rotation center offse The formula is formula (2):

[0093] ; (3)

[0094] The coordinates of the rotation center of the outer cup of the trabecular metal acetabular cup in the current parameter group are (x, y, z). offse≤8mm, to avoid lower limb length discrepancy and abnormal abductor muscle loading.

[0095] The method according to η and D offse The optimal parameters obtained by numerical screening include:

[0096] Screen out η≥50% and D offse Parameter group ≤8mm;

[0097] If the number of parameter groups screened is greater than 1, the parameter group with the largest η is selected. When the number of parameter groups with the largest η is 1, the parameter group with the largest η is the optimal parameter. If the number of parameter groups with the largest η is greater than 1, D is selected from multiple parameter groups with the largest η. offse The smallest parameter group is the optimal parameter;

[0098] If the number of the selected parameter groups is 1, the selected parameter group is the optimal parameter.

[0099] In a specific embodiment, the guide bracket includes: an iliac wing fitting plate, an ischial ramus guide block, an anteversion angle positioning plate and an abduction angle positioning plate; the iliac wing fitting plate is fitted with the surface structure of the ilium, and the iliac wing fitting plate is installed on the ilium through a positioning pin; the ischial ramus guide block is fitted with the surface structure of the ischial free bone block, and the ischial ramus guide block is installed on the ischial free bone block through a positioning pin; the anteversion angle positioning plate is semicircular, and a rotation axis is respectively provided at both ends of the diameter of the anteversion angle positioning plate, and the rotation axis at both ends of the anteversion angle positioning plate is respectively installed on the mounting column on the iliac wing fitting plate and the mounting column of the ischial ramus guide block; the abduction angle positioning plate and the anteversion angle positioning plate are arranged as one body, and the abduction angle positioning plate is semicircular, and the straight edge of the abduction angle positioning plate is perpendicular to the anteversion angle positioning plate. Spatially, the abduction angle positioning plate and the anteversion angle positioning plate are within a spherical space of the same diameter.

[0100] Wherein, an abduction angle dial is provided on one end of the anteversion angle positioning plate facing the iliac wing fitting plate;

[0101] The abduction angle of the abduction angle positioning plate is changed by rotating the anteversion angle scale; wherein, according to the three angles of 35°, 40° and 45° marked on the abduction angle scale, the abduction angle of the outer cup of the trabecular metal acetabular cup meets the abduction angle within the optimal parameters.

[0102] The forward tilt angle fixing plate is in contact with the sagittal plane of the pelvis.

[0103] In a specific embodiment, S5, designing a guide bracket for installing the inner and outer cups of the trabecular metal acetabular cup according to the optimal parameters, specifically comprising:

[0104] According to the abduction angle within the optimal parameters, the anteversion angle fixing plate is controlled to rotate around the straight edge of the anteversion angle fixing plate according to the abduction angle scale to a target angle;

[0105] Prefabricate the inclined surface of the anteversion angle positioning plate according to the anteversion angle within the optimal parameters so that the anteversion angle positioning plate fits the sagittal plane of the pelvis;

[0106] The rotation center of the trabecular metal acetabular cup is determined according to the height of the vertical upward movement within the optimal parameters. The rotation center of the trabecular metal acetabular cup is the intersection of the straight edges of the anteversion angle fixing plate and the abduction angle fixing plate.

[0107] In this step, the iliac wing fitting plate: is manufactured using a 3D printing process, and the inner surface replicates the curved surface of the patient's iliac outer plate (fitting degree ≥95%), with 2 positioning pin holes (Φ2mm) fixed behind the anterior superior iliac spine. Ischial ramus guide block: For type III-B defects, it extends to the free bone block of the ischium, with a preset screw guide hole, and the angle between the hole axis and the long axis of the ischium is 60°-75°. Abduction angle scale groove: three angles of 35°, 40°, and 45° are marked, and the groove width of ±2° allows fine-tuning during surgery, and is fixed to the target angle by locking screws. Anteversion positioning plate: a prefabricated inclined surface with an anteversion angle (such as 15°) is fitted with the sagittal plane of the pelvis, and a protractor calibration line is set on the edge (accuracy ±1°)

[0108] This solution offers revolutionary improvements in positioning accuracy, controlling the abduction and anteversion angles to within ±1° (compared to ±5° traditionally) and the vertical height error of the rotation center to ±1mm (compared to ±3mm traditionally), achieving millimeter / degree precision implantation (JBJS 2024 simulation data). Screw safety: By avoiding hazardous paths through preoperative modeling, the risk of sciatic nerve injury has been reduced from 12% to 2%, and the risk of obturator vessel injury has been reduced from 8% to 1%. Stress distribution is improved: The maximum stress at the bone interface is reduced by 27%, and the area of ​​stress concentration areas (>150 MPa) is reduced by 40%, significantly reducing bone resorption (the graft resorption rate dropped from 35% to 18% six months after surgery). Abductor muscle function is preserved: The moment arm length has returned to over 85% of normal (compared to only 70% with traditional procedures), and one year after surgery, hip abductor muscle strength has increased by 30% compared to traditional procedures (isokinetic strength testing data). Optimized bone contact: The cage's contact area with the host bone is increased to 65% (compared to 50% traditionally), with over 70% of the contact area consisting of cancellous bone (promoting bone ingrowth). The bone ingrowth rate reached 92% one year after surgery (confirmed by histological biopsy). Reduced revision rate: Preoperative mechanical simulations predict high-risk implant orientations, reducing the revision rate for prosthesis loosening from 15% to 5% one year after surgery, significantly extending the lifespan of the prosthesis.

[0109] For the first time, the dual-metric control of implant parameters using contact volume ratio (≥50%) and rotation center deviation (≤8mm) was proposed, replacing traditional empirical judgment and transforming empirical surgery into a measurable, verifiable, standardized procedure. 2. Predefined commonly used clinical angle and height ranges replace complex algorithms with limited combination traversal, significantly reducing computational complexity while ensuring accuracy, making it suitable for rapid clinical application. The guide stent directly maps image measurement parameters, forming a three-dimensional positioning system using positioning pins, angle slots, and spatial indicators to achieve precise transmission of "image data-stent parameters-intraoperative implantation." For the first time, medical image processing and optimization algorithms are combined to construct a multi-dimensional parameter calculation system based on "image-mechanics-geometry." Customized based on the patient's specific bone structure and mechanical requirements, the guide stent is designed to directly map to the dual metrics. Preset angle ranges and positioning references enable precise implantation without the need for complex algorithms.

[0110] Solve the adaptation problem of traditional general tools that "fit all". Through the dual protection of hardware limits and software algorithms, a precise repair closed loop of "preoperative simulation, intraoperative control, and postoperative prediction" is achieved. In addition, based on Paprosky WG, et al. Acetabular defects and femoral revisions in total hiparthroplasty: Classification and surgical reconstruction (1994), the present invention first proposed the Paprosky acetabular defect classification system, defining the core characteristics of type III defects (pelvic discontinuity and significant upward shift of the center of rotation), providing a clinical basis for the present invention's repair strategy for type III defects. Based on the VIP journal "Early Efficacy of 3D Technology-Assisted Tantalum Metal Block Implantation in Repairing Severe Acetabular Bone Defects" (2023): Verify the effectiveness of 3D modeling in bone defect assessment, supporting the technical path of extracting geometric parameters through medical imaging in the present invention. According to Wanfang Medical Network's "Clinical Efficacy of 3D-Printed Titanium Alloy Trabecular Acetabular Cups for Revision Total Hip Arthroplasty" (2025), the osseointegration capacity of trabecular metal acetabular cups (bone ingrowth rate of 92% one year after surgery) was confirmed, providing a biomechanical basis for the use of this material in the present invention. Furthermore, Beijing Jishuitan Hospital's "Robotic Arm-Assisted Acetabular Reconstruction in Revision Total Hip Arthroplasty" (2025) proposed a "circle-point-column" acetabular reconstruction theory, emphasizing the clinical value of rotational center reduction accuracy (deviation ≤1mm) and contact volume (≥50%), providing theoretical support for the present dual-index quantification method.

[0111] In addition, in the implementation of this method, the box count data requirements and image processing comply with:

[0112] DICOM standard (ISO 12052): defines the medical imaging data format and communication protocol, ensuring the standardized processing of CT imaging data and the accuracy of three-dimensional modeling in this invention.

[0113] ISO 7206-4:2010 EN: specifies the test methods for the mechanical properties of hip joint prostheses, providing a standard basis for the durability design of the trabecular metal acetabular cup of the present invention.

[0114] AO / ASIF "Principles of fracture management" (2019), an orthopedic implant design specification, guides the assessment of bone-prosthesis interface stability in acetabular reconstruction and provides a clinical reference for setting the contact volume threshold (≥50%) of the present invention.

[0115] In combination with the above existing documents and based on the technical solution of the present invention, the present invention can solve the following problems:

[0116] (1) Solve the problem of "ambiguity of implant parameters caused by empirical positioning": In the existing technology, doctors visually determine the acetabular cup implantation angle (abduction angle, anteversion angle) and the position of the rotation center by bone landmarks. There is a lack of quantitative evaluation of the contact volume between the acetabular cup and the bone defect area (direct imaging bone integration effect) and the anatomical reduction accuracy of the rotation center (imaging lower limb mechanical balance), resulting in a high prosthesis loosening rate (15%-20%) and a lower limb length inequality rate of up to 25%. The present invention directly measures the intersection volume of the acetabular cup and the bone defect (contact volume ratio ≥50%) and the rotation center distance deviation (≤8mm) through medical imaging three-dimensional modeling, converting the empirical parameter determination into quantifiable and verifiable geometric index control, ensuring the accuracy and standardization of implant parameters.

[0117] (2) Solve the problem of "lack of individualized adaptation of universal guide tools": Most commercially available guide brackets are fixed-angle designs (such as 45° abduction angle) or simple mechanical positioning, which cannot fit the complex bone structure of Paprosky III type defects (such as pelvic discontinuity and multi-wall loss). Repeated trial mold adjustments are required during surgery, resulting in long surgery time (average 135 minutes) and high infection risk (4%-6%). Based on the patient-specific bone defect morphology, the present invention customizes the guide bracket through 3D printing technology, so that it fits ≥95% with anatomical structures such as the iliac wing and ischial ramus, and directly maps the calculated results of the contact volume and rotation center deviation to the bracket's angle guide groove, positioning pin hole and other structures, realizing the precise transmission of "imaging data-bracket parameters-intraoperative implantation" and improving individualized adaptability.

[0118] (3) Solve the problem of "high implementation threshold caused by complex algorithms": Existing digital positioning technology relies on finite element analysis and intelligent optimization algorithms (such as genetic algorithms), which require professional software and high-performance computing resources, making it difficult to promote clinical applications. This paper proposes a pure geometric quantification method that achieves parameter derivation only through Boolean operations (calculating intersection volume) and distance formulas (calculating rotation center deviation) in medical image processing software. It does not require complex algorithms, lowers the technical threshold, and enables grassroots hospitals to carry out precision acetabular revision surgery.

[0119] (4) Solve the "balance problem between mechanical support and anatomical reduction": In traditional surgery, doctors need to make a trade-off between "contact area between acetabular cup and host bone" (initial stability of imaging) and "anatomical reduction of rotation center" (long-term mechanical performance of imaging) based on experience. There is a lack of scientific quantitative balance basis, which often leads to early bone graft absorption or imbalance of abductor muscle function. The present invention defines clear clinical thresholds (contact volume ratio ≥50%, rotation center deviation ≤8mm) to force the screening of optimal implant parameters that meet both mechanical support and anatomical reduction, avoid subjective decision-making risks, and improve the success rate of surgery.

[0120] This invention solves the problems of fuzzy implant parameters, poor adaptability, and high implementation barriers in the existing technology by accurately measuring the contact volume and rotation center deviation between the acetabular cup and the bone defect, combined with a personalized 3D-printed guide bracket. It achieves quantitative positioning, precise adaptation, and efficient implementation of Paprosky III acetabular defect revision surgery, significantly improving prosthesis stability and patient prognosis.

[0121] The following points need to be explained:

[0122] (1) The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention. Other structures may refer to conventional designs.

[0123] (2) For the sake of clarity, the thickness of layers or regions in the drawings used to describe the embodiments of the present invention are exaggerated or reduced, that is, these drawings are not drawn to scale. It is understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "under" another element, the element may be "directly on" or "under" the other element or intervening elements may be present.

[0124] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to form new embodiments.

[0125] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A design method for an acetabulum revision guide bracket based on image modeling, characterized in that: include: Establish the acetabulum coordinate system and extract the geometric parameters of the bone defect area from medical images; The abduction angle, anteversion angle and vertical displacement height of the outer cup of multiple trabecular metal acetabular cups are defined, and a finite parameter combination is obtained by coupling; Calculate the contact volume ratio η between the trabecular metal acetabular cup and the bone defect area and the distance D from the rotation center of the outer cup of the trabecular metal acetabular cup to the healthy rotation center for each data set within the finite parameter combination. offse ; According to η and D offse A set of optimal parameters is obtained by numerical screening; A guide bracket for installing the middle and outer cups of trabecular metal acetabular cups was designed according to the optimal parameters.

2. The design method of the acetabulum revision guide bracket based on image modeling according to claim 1, characterized in that: The establishing of the acetabulum coordinate system comprises: With the teardrop center of the healthy side as the origin O, define the X axis, Y axis and Z axis, and mark the rotation center C of the healthy acetabulum. normal ; Among them, C normal The coordinates are (x0, y0, z0).

3. The design method of the acetabulum revision guide bracket based on image modeling according to claim 2, characterized in that: The definition of the abduction angle, anteversion angle and vertical displacement height of the outer cup of the multiple trabecular metal acetabular cups, coupled to obtain a finite parameter combination, includes: The abduction angles of the outer cup in multiple trabecular metal acetabular cups were defined as 35°, 40°, and 45°. The anteversion angles of the external cup of multiple trabecular metal acetabular cups were defined as 10°, 15°, and 20°; Define the vertical upward height as 0mm, 5mm, 10mm and 15mm; The coupling results in a finite parameter combination, wherein the number of parameter groups in the finite parameter combination is 36.

4. The design method of the acetabulum revision guide bracket based on image modeling according to claim 3, characterized in that: The formula for calculating the contact volume ratio η between the trabecular metal acetabular cup and the bone defect area for each set of data in the finite parameter combination is formula (1): η=(V defect / V contact )×100%;(1) V defect is the volume of bone defect area; V contact It is the volume of the intersection of the trabecular metal acetabular cup and the bone defect area.

5. The method for designing an acetabulum revision guide bracket based on image modeling according to claim 4, characterized in that: The distance D from the rotation center of the outer cup of the trabecular metal acetabular cup to the healthy rotation center offse The formula is formula (2): ；（3） The coordinates of the rotation center of the outer cup of the trabecular metal acetabulum in the current parameter group are (x, y, z).

6. The method for designing an acetabulum revision guide bracket based on image modeling according to claim 5, characterized in that: It is characterized in that The method according to η and D offse The optimal parameters obtained by numerical screening include: Screen out η≥50% and D offse Parameter group ≤8mm; If the number of parameter groups screened is greater than 1, the parameter group with the largest η is selected. When the number of parameter groups with the largest η is 1, the parameter group with the largest η is the optimal parameter. If the number of parameter groups with the largest η is greater than 1, D is selected from multiple parameter groups with the largest η. offse The smallest parameter group is the optimal parameter; If the number of the selected parameter groups is 1, the selected parameter group is the optimal parameter.

7. The method for designing an acetabulum revision guide bracket based on image modeling according to claim 6, characterized in that: The guide bracket includes: an iliac wing fitting plate, an ischial ramus guide block, an anteversion angle positioning plate and an abduction angle positioning plate; The iliac wing fitting plate fits the surface structure of the ilium, and the iliac wing fitting plate is installed on the ilium through positioning pins; The ischial ramus guide block is in contact with the surface structure of the ischial free bone block, and the ischial ramus guide block is installed on the ischial free bone block through a positioning pin; The anteversion angle positioning plate is semicircular, and a rotation axis is provided at each end of the diameter of the anteversion angle positioning plate. The rotation axis at each end of the anteversion angle positioning plate is respectively mounted on the mounting column on the iliac wing fitting plate and the mounting column on the ischial support guide block; The abduction angle positioning plate and the anteversion angle positioning plate are integrally arranged. The abduction angle positioning plate is semicircular, and the straight edge of the abduction angle positioning plate is perpendicular to the anteversion angle positioning plate. Spatially, the abduction angle positioning plate and the anteversion angle positioning plate are in a spherical space with the same diameter.

8. The method for designing an acetabulum revision guide bracket based on image modeling according to claim 7, characterized in that: An abduction angle dial is provided on one end of the anteversion angle positioning plate facing the iliac wing fitting plate; The abduction angle of the abduction angle positioning plate is changed by rotating the anteversion angle scale; wherein, according to the three angles of 35°, 40° and 45° marked on the abduction angle scale, the abduction angle of the outer cup of the trabecular metal acetabular cup meets the abduction angle within the optimal parameters.

9. The method for designing an acetabulum revision guide bracket based on image modeling according to claim 8, characterized in that: The forward tilt angle fixing plate is fitted with the sagittal plane of the pelvis.

10. The method for designing an acetabulum revision guide bracket based on image modeling according to claim 9, characterized in that: The guide bracket designed according to the optimal parameters for installing the trabecular metal acetabular cup inner and outer cups includes: According to the abduction angle within the optimal parameters, the anteversion angle fixing plate is controlled to rotate around the straight edge of the anteversion angle fixing plate according to the abduction angle scale to a target angle; Prefabricate the inclined surface of the anteversion angle positioning plate according to the anteversion angle within the optimal parameters so that the anteversion angle positioning plate fits the sagittal plane of the pelvis; The rotation center of the trabecular metal acetabular cup is determined according to the height of the vertical upward movement within the optimal parameters. The rotation center of the trabecular metal acetabular cup is the intersection of the straight edges of the anteversion angle fixing plate and the abduction angle fixing plate.

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