Self-adaptive manufacturing method of anterior cervical titanium cage

Abstract

The invention relates to the technical field of medical implant manufacturing, in particular to a self-adaptive manufacturing method of an anterior cervical titanium cage, which comprises the following steps: acquiring cervical vertebra CT data of a target object; performing three-dimensional reconstruction on the cervical vertebra CT data to obtain a complete three-dimensional centrum model, and analyzing the cervical vertebra CT data and the complete three-dimensional centrum model to obtain model correction parameters; based on the expected excision amount of the target object, ACCF simulation operation is carried out on the three-dimensional vertebral body model, and a cervical vertebra secondary total excision model after simulation operation is obtained; based on the cervical vertebra secondary total resection model and the model correction parameters, a primary structure model of the anterior cervical titanium cage is obtained; performing ACCF simulation installation by using the primary structure model, and adjusting the primary structure model to obtain a secondary structure model; making an anterior cervical titanium cage of the target object based on the secondary structure model; the contact area of the titanium cage and the vertebral body is remarkably increased, local stress can be dispersed, and the sedimentation probability of the titanium cage after the ACCF operation is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of medical implant manufacturing, in particular to a self-adaptive manufacturing method of an anterior cervical titanium cage. Background Art

[0002] ACCF (Anterior cervical corpectomy and fusion) is a classic surgical procedure for treating cervical spine diseases, including cervical spondylotic myelopathy, ossification of the posterior longitudinal ligament, cervical deformity, etc. It is especially used for cervical spine diseases with compression of the anterior spinal cord because of its good decompression effect and high fusion rate.

[0003] Vertebral structure reconstruction is a crucial step in ACCF surgery, impacting the stability and fusion rate of the cervical spine. Autologous bone or allogeneic bone, alone or in combination with a titanium cage, is an important reconstruction method. Autologous bone reconstruction is currently being used less frequently due to the high incidence of donor site complications. Allogeneic bone is less commonly used due to its limited availability and potential rejection. Titanium cages, on the other hand, are widely available, provide immediate postoperative stability, and, combined with in situ bone grafting, offer a high fusion rate, making them widely used. Although titanium cages are widely used in ACCF, years of clinical testing have shown that some postoperative complications still occur, particularly with TMC (titanium mesh cage)-related titanium cage settlement and internal fixation failure. This is closely related to the design flaws of the TMC and the resulting biomechanical changes in the cervical spine.

[0004] The main drawback of TMC is the small contact area between the TMC and endplate, which leads to uneven stress distribution and stress concentration, further causing TMC subsidence and stress changes at the internal fixation-bone interface.

[0005] Chinese patent application publication number CN110897695B discloses a lower cervical anatomical titanium cage, comprising: a titanium cage body, the upper end of the titanium cage body being a dome structure, the lower end being an oblique structure, a mesh structure being disposed between the dome structure and the oblique structure, the mesh structure being connected to the dome structure and the oblique structure respectively; the mesh structure comprising a first front surface, a first rear surface, a first left side surface, and a first right side surface, the first front surface and the first rear surface both being arc-shaped structures, and the first left side surface and the first right side surface both being planar structures. Based on the measurement results of cervical anatomical data, the upper end of the lower cervical anatomical titanium cage is designed with a dome structure, and the lower end of the lower cervical anatomical titanium cage is designed with an oblique structure, simulating the angle of the cervical surgical segment, thereby expanding the contact area between the titanium cage and the cervical endplate, reducing stress concentration, and evenly distributing stress on the endplate surface, thereby reducing the incidence of titanium cage collapse.

[0006] It can be seen that the above-mentioned lower cervical anatomical titanium cage has the following problems: the contact area between the upper dome structure and the lower oblique structure with the end plates of different patients is unstable, and the problem of titanium cage collapse caused by stress concentration still occurs. Summary of the Invention

[0007] To this end, the present invention provides an adaptive manufacturing method for anterior cervical titanium cage, which is used to overcome the problem in the prior art that the contact area between the titanium cage and the end plate is unstable and stress concentration is prone to cause collapse of the titanium cage.

[0008] To achieve the above objectives, the present invention provides a method for adaptively manufacturing an anterior cervical titanium cage, comprising:

[0009] Step S1, obtaining cervical spine CT data of the target object;

[0010] Step S2, performing three-dimensional reconstruction on the cervical vertebrae CT data to obtain a complete three-dimensional vertebrae model, and analyzing the cervical vertebrae CT data and the complete three-dimensional vertebrae model to obtain model correction parameters;

[0011] Step S3, performing ACCF simulated resection on the three-dimensional vertebral model based on the expected resection amount of the target cervical vertebra of the target object, to obtain a cervical subtotal resection model after simulated resection;

[0012] Step S4, obtaining a primary structural model of anterior cervical titanium cage based on the subtotal cervical vertebra resection model and the model correction parameters;

[0013] Step S5, performing ACCF simulation installation using the primary structure model, and adjusting the primary structure model based on the cervical vertebra installation model after the simulated installation and the model correction parameters to obtain a secondary structure model;

[0014] Step S6, manufacturing an anterior cervical titanium cage for the target subject based on the secondary structure model;

[0015] The anterior cervical titanium cage includes a titanium cage frame body, anti-sinking rings arranged at both ends of the titanium cage frame body and in contact with the cervical vertebral end plates, and ear-shaped fixing parts arranged at both ends of the titanium cage frame body.

[0016] Furthermore, the anterior cervical titanium cage comprises:

[0017] The anti-sinking ring is a hollow ring structure whose surface is in contact with the bony endplate of the cervical vertebra. The anti-sinking ring includes an upper anti-sinking ring and a lower anti-sinking ring. The upper surface of the upper anti-sinking ring is in contact with the curved surface of the lower endplate of the bony endplate of the upper adjacent cervical vertebra, and the lower surface of the lower anti-sinking ring is in contact with the curved surface of the upper endplate of the bony endplate of the lower adjacent cervical vertebra.

[0018] The titanium cage skeleton body is a hollow columnar structure with mesh holes, the upper end of the titanium cage skeleton body is connected to the upper anti-sinking ring, and the lower end of the titanium cage skeleton body is connected to the lower anti-sinking ring;

[0019] The ear-shaped fixing portion includes an ear-shaped fixing plate and a connecting area, wherein the ear-shaped fixing plate includes an upper ear-shaped fixing plate and a lower ear-shaped fixing plate respectively provided with a screw hole and a semicircular weight-reducing groove, and the connecting area includes an upper connecting area and a lower connecting area, the upper ear-shaped fixing plate is connected to the upper anti-sinking ring through the upper connecting area and is parallel to the vertebral surface of the upper adjacent cervical vertebra, and the lower ear-shaped fixing plate is connected to the lower anti-sinking ring through the lower connecting area and is parallel to the vertebral surface of the lower adjacent cervical vertebra;

[0020] The anti-sinking ring, the titanium cage skeleton body, the connecting area and the ear-shaped fixing plate are integrally fixedly connected.

[0021] Furthermore, the step S2 includes:

[0022] Step S21, importing the cervical vertebra CT data into a medical imaging control system for three-dimensional reconstruction and segmenting the vertebrae to obtain six separate vertebral body models of C2 to C7;

[0023] Step S22, importing each of the split cervical vertebrae models into reverse engineering software for model optimization and conversion into a solid model;

[0024] Step S23, importing each of the solid models into a three-dimensional design software to generate cancellous bone, cortical bone, bony endplate, posterior structure, intervertebral disc, and ligament complex, and adjusting the cervical spine posture to the ACCF surgical posture to obtain the complete three-dimensional vertebral body model;

[0025] Step S24: Analyze the cervical vertebrae CT data and the complete three-dimensional vertebral body model to obtain the model correction parameters.

[0026] Furthermore, the step S24 includes:

[0027] Step S241, constructing a deformation trajectory of the esophagus during a swallowing cycle based on the cervical spine CT data, and obtaining a minimum spacing distance between the esophageal wall and the front edge of the titanium cage skeleton body;

[0028] Step S242, obtaining a depth adjustment parameter according to the minimum separation distance and the expected resection amount of the target object;

[0029] Step S243: Divide the upper end plate and the lower end plate into several partitions according to the bone density distribution of the bony end plate, and calculate the contact area threshold of the anti-sinking ring corresponding to the upper end plate and the lower end plate in each partition.

[0030] Furthermore, in step S243, the contact area threshold is negatively correlated with the bone density of the bony endplate.

[0031] Furthermore, the step S4 includes:

[0032] Step S41, constructing an upper ear-shaped fixation plate model and a lower ear-shaped fixation plate model based on the vertebral surface of the upper adjacent cervical vertebra and the lower adjacent cervical vertebra close to the esophagus side of the target cervical vertebra;

[0033] Step S42, constructing an upper anti-sinking ring model based on the lower end plate of the upper adjacent cervical vertebral body of the target cervical vertebral body, and constructing a lower anti-sinking ring model based on the upper end plate of the lower adjacent cervical vertebral body of the target cervical vertebral body;

[0034] Step S43, constructing an upper connecting portion model based on the upper ear-shaped fixing plate model and the upper anti-sinking ring model, and constructing a lower connecting portion model based on the lower ear-shaped fixing plate model and the lower anti-sinking ring model;

[0035] Step S44, constructing a titanium cage skeleton main body model according to the upper anti-sinking ring model and the lower anti-sinking ring model;

[0036] Step S45, connecting and merging the upper anti-sinking ring model, the lower anti-sinking ring model, the upper ear-shaped fixing plate model, the lower ear-shaped fixing plate model, the upper connecting part model, the lower connecting part model and the titanium cage skeleton main body model to obtain the primary structure model.

[0037] Furthermore, the step S42 includes:

[0038] Step S421, constructing a first-level upper anti-sinking ring model that is completely fitted with the lower end plate, and a first-level lower anti-sinking ring model that is completely fitted with the upper end plate;

[0039] Step S422: Calculate the ratio of the middle hole area of ​​the first-level upper anti-sinking ring model and the first-level lower anti-sinking ring model to the larger area of ​​the upper end plate and the lower end plate; if the ratio is less than a ratio threshold, modify the middle hole area so that the ratio of the middle hole area to the corresponding end plate area is greater than or equal to the ratio threshold, thereby obtaining a second-level upper anti-sinking ring model and a second-level lower anti-sinking ring model;

[0040] Step S423, detecting a sudden change region in the secondary upper anti-sinking ring model and the secondary lower anti-sinking ring model where the curvature is greater than a curvature threshold;

[0041] Step S424 , performing curvature correction on the sudden change region so that the corrected curvature is less than or equal to the curvature threshold, thereby obtaining the upper anti-sinking ring model and the lower anti-sinking ring model.

[0042] Furthermore, in step S421, the position of the anti-sinking ring on the corresponding end plate is determined according to the depth adjustment parameter, so that the contour of the sunken area formed by the titanium cage skeleton body and the ear-shaped fixing portion is located outside the envelope surface of the esophageal deformation trajectory.

[0043] Furthermore, the step S5 includes:

[0044] Step S51, simulating the internal fixation installation of ACCF surgery, placing the upper anti-sinking ring model, the lower anti-sinking ring model, and the titanium cage skeleton main body model in the primary structure model into a decompression groove, so that the anti-sinking ring fits with the corresponding cervical vertebral endplate, and then fixing the ear-shaped fixation plate model to the surface of the corresponding cervical vertebra with screws to complete the ACCF simulation installation, wherein the decompression groove is obtained by simulating the resection of the target cervical vertebra of the target object by ACCF;

[0045] Step S52, determine whether the contact area of ​​the end plates corresponding to the upper anti-sinking ring model and the lower anti-sinking ring model in the primary structure model and the cervical vertebral body in each partition is less than the corresponding contact area threshold; if the contact area is less than the corresponding contact area threshold, correct the surface of the corresponding partition of the corresponding anti-sinking ring so that the contact area is greater than or equal to the contact area threshold to obtain the secondary structure model.

[0046] Furthermore, in step S51, when the upper anti-sinking ring model, the lower anti-sinking ring model and the titanium cage skeleton main body model in the primary structure model are placed in the decompression groove, the simulated normal contact stresses of the upper anti-sinking ring model and the lower anti-sinking ring model with the cervical vertebral end plate are respectively obtained in real time. If the simulated normal contact stress is greater than the stress safety threshold, the curvature of the corresponding anti-sinking ring is corrected so that the simulated normal contact stress between the corrected anti-sinking ring and the cervical vertebral end plate during the implantation process is less than or equal to the stress safety threshold.

[0047] The beneficial effect of the present invention lies in that the present invention obtains a high-precision three-dimensional virtual model of the cervical spine through three-dimensional reconstruction technology based on the patient's cervical spine CT scan data, performs virtual simulation of anterior cervical vertebral subtotal vertebral resection and fusion on this model, obtains a virtual model after vertebral subtotal resection, and then uses virtual design software to perform personalized anterior cervical titanium cage design, optimizes the design structure of the titanium cage body-bone contact surface, adopts an anti-sinking ring structure, so that the end face of the titanium cage and the end plate form a face-to-face anatomical matching relationship, compared with the existing clinical titanium cage, the contact area between the titanium cage and the vertebral body is significantly increased, which helps to disperse local stress and prevent excessive local stress concentration, thereby reducing the occurrence of titanium cage settlement complications after ACCF surgery.

[0048] Furthermore, the present invention integrates the fixing steel plate and the titanium cage body into an integrated design, thereby ensuring the internal fixation strength of the titanium cage while improving the stability of the internal fixation.

[0049] Furthermore, the present invention greatly reduces the contact area between the titanium cage and the esophagus through the hollow indentation design of the front edge of the titanium cage, thereby reducing the irritation of the titanium cage to the esophagus, helping to reduce esophageal-related complications after ACCF surgery, and improving the patient's symptoms of difficulty eating after surgery.

[0050] Furthermore, the present invention constructs the deformation trajectory of the esophagus during the swallowing cycle based on CT scanning data, and sets the hollow indentation of the front edge of the titanium cage to different depths for different patients to prevent compression of the esophagus caused by too shallow hollow indentation or stagnation of swallowed objects caused by too deep hollow indentation.

[0051] Furthermore, the present invention controls the differentiated contact area based on the zoning of the cervical vertebral endplates, so that the supporting force distribution of the anti-subsidence ring matches the endplate bone density gradient, ensuring that the high-density area bears more mechanical loads, and the low-density area reduces the unit area pressure through area compensation, thereby reducing the occurrence of titanium cage settlement complications after ACCF surgery and accelerating the long-term bony fusion process.

[0052] Furthermore, the present invention corrects the curvature of the anti-sinking ring contact surface by detecting bony protrusion areas (such as osteophytes or calcified areas) with sudden changes in curvature on the endplate surface, so that the corrected anti-sinking ring surface forms a smooth transition with the endplate surface. This correction avoids local stress concentration caused by sudden changes in curvature, while preventing mechanical interference between the edge of the anti-sinking ring and the bony protrusion during implantation, ensuring the smoothness of the titanium cage implant path. By controlling the corrected curvature to not exceed the physiological curvature threshold of the endplate cartilage, the anatomical matching relationship between the anti-sinking ring and the endplate is maintained, and the risk of postoperative titanium cage subsidence is reduced.

[0053] Furthermore, during the virtual implantation process, the collision interference volume between the anti-subsidence ring and the bony structure of the endplate is detected in real time. The curvature of the anti-subsidence ring edge is dynamically adjusted to ensure that the collision interference volume remains below the safety threshold. This correction method optimizes the implant path compatibility of the anti-subsidence ring, avoiding microfractures or cartilage damage in the endplate caused by forced implantation, while also reducing the duration of the operation caused by repeated adjustments to the titanium cage position. The corrected curvature distribution allows the anti-subsidence ring to adaptively conform to the endplate surface during implantation, improving surgical safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a flow chart of a method for adaptively manufacturing an anterior cervical titanium cage according to an embodiment of the present invention;

[0055] Figure 2 A perspective view of a schematic diagram of an anterior cervical titanium cage according to an embodiment of the present invention;

[0056] Figure 3 This is a cross-sectional schematic diagram of a simulated installation of an anterior cervical titanium cage according to an embodiment of the present invention;

[0057] Figure 4 This is an actual image of the secondary structure model of the anterior cervical titanium cage according to an embodiment of the present invention;

[0058] Figure 5 This is an actual image of the secondary structure model of the anterior cervical titanium cage during simulated installation according to an embodiment of the present invention;

[0059] In the figure: 1-titanium cage skeleton body; 21-upper anti-sinking ring; 22-lower anti-sinking ring; 311-upper ear-shaped fixing plate; 3111-upper weight-reducing groove; 3112-upper fixing screw hole; 312-lower ear-shaped fixing plate; 3121-lower weight-reducing groove; 3122-lower fixing screw hole; 321-upper connecting area; 322-lower connecting area; 4-cervical vertebra; 5-screw. DETAILED DESCRIPTION

[0060] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0061] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0062] It should be noted that, in the description of the present invention, terms such as "upper", "lower", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0063] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted" and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0064] See also Figures 2 to 5As shown, it is a stereoscopic diagram of a schematic diagram of an anterior cervical titanium cage according to an embodiment of the present invention, a cross-sectional diagram of a schematic diagram of an anterior cervical titanium cage according to an embodiment of the present invention during simulated installation, an actual image of a secondary structure model of an anterior cervical titanium cage according to an embodiment of the present invention, and an actual image of a secondary structure model of an anterior cervical titanium cage according to an embodiment of the present invention during simulated installation, including:

[0065] A titanium cage skeleton body 1, anti-sinking rings arranged at both ends of the titanium cage skeleton body 1 and in contact with the cervical vertebral end plates, and ear-shaped fixing parts arranged at both ends of the titanium cage skeleton body 1.

[0066] The anti-sinking ring includes an upper anti-sinking ring 21 and a lower anti-sinking ring 22. The upper surface of the upper anti-sinking ring 21 fits with the curved surface of the lower end plate of the upper adjacent cervical vertebra 4, and the lower surface of the lower anti-sinking ring 22 fits with the curved surface of the upper end plate of the lower adjacent cervical vertebra 4.

[0067] The titanium cage skeleton body 1 is a hollow columnar structure with diamond mesh, the upper end of which is connected to the upper anti-sinking ring 21, and the lower end of which is connected to the lower anti-sinking ring 22;

[0068] The ear-shaped fixing portion includes an ear-shaped fixing plate and a connecting area, wherein the ear-shaped fixing plate includes an upper ear-shaped fixing plate 311 and a lower ear-shaped fixing plate 312; the connecting area includes an upper connecting area 321 and a lower connecting area 322, the upper ear-shaped fixing plate 311 is connected to the upper anti-sinking ring 21 through the upper connecting area 321 and is parallel to the vertebral surface of the upper adjacent cervical vertebra 4, and the lower ear-shaped fixing plate 312 is connected to the lower anti-sinking ring 22 through the lower connecting area 322 and is parallel to the vertebral surface of the lower adjacent cervical vertebra 4;

[0069] The upper ear-shaped fixing plate 311 is provided with symmetrical upper fixing screw holes 3112 and a semicircular upper weight-reducing groove 3111 between the two screw holes, and the lower ear-shaped fixing plate 312 is provided with symmetrical lower fixing screw holes 3122 and a semicircular lower weight-reducing groove 3121 between the two screw holes;

[0070] The upper ear-shaped fixing plate 311 and the lower ear-shaped fixing plate 312 are fixedly connected to the vertebral body via screws 5 .

[0071] The anti-sinking ring, the titanium cage skeleton body 1, the connecting area and the ear-shaped fixing plate are integrally fixedly connected.

[0072] In practice, the corners of the anti-sinking ring, the connecting area and the ear-shaped fixing plate are provided with rounded chamfers. Preferably, the radius of the rounded chamfers is 0.2 mm to 1 mm.

[0073] Please continue reading Figure 1 As shown, it is a flow chart of the adaptive manufacturing method of the anterior cervical titanium cage according to an embodiment of the present invention, comprising:

[0074] Step S1, obtaining cervical spine CT data of the target object;

[0075] During implementation, the method includes performing a supine cervical spine CT scan and a swallowing dynamic CT scan on the target subject; wherein, the swallowing dynamic CT scan requires the target subject to swallow a gel containing 2% diatrizoate contrast agent (simulating a food bolus), and continuously acquires images for 10 seconds at a rate of 8 frames per second to obtain a complete swallowing dynamic image sequence.

[0076] Step S2, performing three-dimensional reconstruction on the cervical vertebrae CT data to obtain a complete three-dimensional vertebrae model, and analyzing the cervical vertebrae CT data and the complete three-dimensional vertebrae model to obtain model correction parameters;

[0077] Specifically, step S2 includes:

[0078] Step S21, importing the cervical vertebra CT data into a medical imaging control system for three-dimensional reconstruction and segmenting the vertebrae to obtain six separate vertebral body models of C2 to C7;

[0079] In the implementation, the target subject's supine cervical spine CT data were imported into a medical imaging control system, such as MIMICS14.0 (Materialise Corporation, Belgium). The C2 to C7 vertebral contours were extracted using a threshold segmentation algorithm to generate a split vertebral model containing the vertebral body, pedicle, and facet joints.

[0080] Step S22, importing each of the split cervical vertebrae models into reverse engineering software for model optimization and conversion into a solid model;

[0081] During implementation, the split vertebral model was imported into reverse engineering software, such as Geomagic (Geomagic Studio 2021; Geomagic, NC, USA), and CT artifacts were eliminated using a surface smoothing algorithm. Non-uniform rational B-spline (NURBS) surface reconstruction technology was used to generate a solid model. The edges of the vertebral endplates were sharpened to preserve anatomical features.

[0082] Step S23, importing each of the solid models into a three-dimensional design software to generate cancellous bone, cortical bone, bony endplate, posterior structure, intervertebral disc, and ligament complex, and adjusting the cervical spine posture to the ACCF surgical posture to obtain the complete three-dimensional vertebral body model;

[0083] During implementation, the solid model is imported into 3D design software, such as SolidWorks 2022, and the cancellous bone and cortical bone areas are divided according to the CT grayscale value; the bony endplate, posterior structure, intervertebral disc and ligament complex are generated through the preset model; and the cervical spine is adjusted to the ACCF standard surgical position (flexion angle 15°±3°, lateral tilt angle 0°).

[0084] Step S24: Analyze the cervical vertebrae CT data and the complete three-dimensional vertebral body model to obtain the model correction parameters.

[0085] Specifically, the step S24 includes:

[0086] Step S241, constructing a deformation trajectory of the esophagus during a swallowing cycle based on the cervical spine CT data, and obtaining a minimum spacing distance between the esophageal wall and the front edge of the titanium cage skeleton body 1;

[0087] In the implementation, MIMICS 14.0 software was used to extract the esophageal wall contour using a threshold segmentation algorithm, and a region growing algorithm was used to remove tracheal interference. The middle section of the anterior esophageal wall was selected, and a continuous motion trajectory was generated using B-spline curve fitting. The esophageal motion envelope was constructed using non-uniform rational B-spline (NURBS) surfaces to obtain the maximum radial displacement of the esophageal wall during swallowing.

[0088] The calculation formula of the minimum separation distance is specifically:

[0089] d min =Δd+d safe ;

[0090] Among them, d min is the minimum spacing distance, in mm; △d is the maximum radial displacement of the esophageal wall during swallowing, in mm; d safe The safety interval is in mm. According to clinical research data, it is preferably 2 mm.

[0091] Step S242, obtaining a depth adjustment parameter according to the minimum separation distance and the expected resection amount of the target object;

[0092] In implementation, the calculation formula of the depth adjustment parameter is specifically:

[0093] ΔH=d min -(QeD);

[0094] Among them, △H is the depth adjustment parameter, unit is mm; Q is the depth of the expected resection amount, unit is mm; e is the reference distance between the titanium cage skeleton body 1 and the inner wall of the decompression groove, unit is mm, preferably, 0.5mm~1mm; D is the outer diameter of the titanium cage skeleton body 1, unit is mm.

[0095] It can be understood that the part (QeD) in the formula is the distance between the front edge of the titanium cage and the esophageal wall when the titanium cage is implanted according to the reference distance, which is different from the minimum spacing distance d min The difference is the distance that the anti-sinking ring needs to be adjusted inward.

[0096] Step S243: Divide the upper end plate and the lower end plate into several partitions according to the bone density distribution of the bony end plate, and calculate the contact area threshold of the anti-sinking ring corresponding to the upper end plate and the lower end plate in each partition.

[0097] Specifically, in step S243, the contact area threshold is negatively correlated with bone density.

[0098] In practice, the endplate surface is divided into square grid partitions. Preferably, the grid size is 3 mm × 3 mm. The bone density value of each grid is calculated based on the CT value (HU) and the contact area threshold is calculated. The calculation formula of the contact area threshold is specifically:

[0099]

[0100] Among them, S i is the contact area threshold of the i-th partition, ρ i is the bone density value of the i-th partition, in mg / cm 3 ρ min is the minimum bone density value of the end plate; ρ max is the maximum bone density of the end plate; a is the compensation coefficient, which is calibrated by clinical bone strength experiments. Preferably, a is 0.3; S 基准 is the baseline contact area threshold, in mm 2 , which is calibrated by clinical bone strength experiments, preferably, S 基准 Take 5.4mm 2 .

[0101] It is understandable that endplate bone density (quantified by CT value) directly reflects the mechanical strength of local bone tissue. Low-density areas (such as osteoporotic areas) have sparse trabeculae and weak load-bearing capacity, which are prone to microfractures caused by stress concentration. High-density areas (such as sclerotic areas) are too rigid, and excessive contact may compress bone tissue and hinder bone ingrowth. When the bone density of a certain area is low, increasing the contact area threshold (up to 7.02 mm) in that area will increase the contact area threshold. 2 ), so that the anti-sinking ring has a larger actual contact area in this area. The increase in contact area reduces the pressure per unit area, avoiding the collapse of the trabeculae of the cervical vertebral end plate due to stress overload; when the bone density of a certain area is high, the contact area threshold is reduced (to the lowest S benchmark, i.e. 5.4mm 2), allowing the anti-sinking ring to form a larger gap with the end plate in this area. The gap provides a channel for bone cell migration and blood vessel ingrowth, promotes long-term bone fusion, and reduces the compression damage of rigid contact to high-density bone.

[0102] The present invention controls the differentiated contact area based on partitions, so that the supporting force distribution of the anti-subsidence ring matches the endplate bone density gradient, ensuring that the high-density area bears more mechanical loads, and the low-density area reduces the unit area pressure through area compensation. The overall stress peak is greatly reduced compared with the uniform contact design; at the same time, the contact area is reduced in the high-density area to retain microgaps, providing channels for bone cell migration and vascularization, and accelerating the long-term bony fusion process.

[0103] Step S3, performing ACCF simulated resection on the three-dimensional vertebral model based on the expected resection amount of the target cervical vertebra of the target object, to obtain a cervical subtotal resection model after simulated resection;

[0104] During implementation, the ACCF simulation surgery is the simulated resection part of the ACCF procedure. Based on the expected resection amount of the target object, part of the vertebra within the bilateral uncovertebral joints of the target cervical vertebra is removed to obtain a decompression groove, and the intervertebral disc between the target cervical vertebra and the four cervical vertebrae above and below it, as well as the corresponding anterior longitudinal ligament and posterior longitudinal ligament are removed.

[0105] Step S4, obtaining a primary structural model of anterior cervical titanium cage based on the subtotal cervical vertebra resection model and the model correction parameters;

[0106] Specifically, step S4 includes:

[0107] Step S41, constructing an upper ear-shaped fixation plate model and a lower ear-shaped fixation plate model based on the vertebral body surfaces of the upper adjacent cervical vertebra 4 and the lower adjacent cervical vertebra 4 close to the esophagus side of the target cervical vertebra;

[0108] During implementation, the point cloud data of the anterior surface of the upper vertebra in the cervical subtotal resection model is extracted, and the plane is fitted by the least squares method to determine the reference plane of the upper ear-shaped fixation plate 311, and a rectangular base plate is created on the reference plane; the upper fixing screw hole 3112 and the semicircular upper weight-reducing groove 3111 between the two screw holes are set on the rectangular base plate according to preset dimensions; and the lower ear-shaped fixation plate 312 is constructed using the same method.

[0109] It can be understood that the ear-shaped fixation plate is parallel to the anterior surface of the vertebral body, so that the axial direction of the screw hole is consistent with the principal stress direction of the cortical bone, thereby reducing the shear force of the screw 5 and reducing the risk of the screw 5 loosening.

[0110] Step S42, constructing an upper anti-sinking ring model based on the lower end plate of the upper adjacent cervical vertebral body 4 of the target cervical vertebral body, and constructing a lower anti-sinking ring model based on the upper end plate of the lower adjacent cervical vertebral body 4 of the target cervical vertebral body;

[0111] Specifically, step S42 includes:

[0112] Step S421, constructing a first-level upper anti-sinking ring model that is completely fitted with the lower end plate, and a first-level lower anti-sinking ring model that is completely fitted with the upper end plate;

[0113] Specifically, in step S421, the position of the anti-sinking ring on the corresponding end plate is determined according to the depth adjustment parameter, so that the contour of the sunken area formed by the titanium cage skeleton body 1 and the ear-shaped fixing portion is always located outside the esophageal motion envelope.

[0114] During implementation, the implantation depth of the titanium cage skeleton body 1 is determined according to the depth adjustment parameter ΔH, and then the position of the anti-sinking ring on the corresponding end plate is determined; the surface fitting tool of Geomagic Wrap is used to completely fit the initial anti-sinking ring surface with the exposed area of ​​the end plate (maximum gap ≤0.05mm) to obtain the first-level anti-sinking ring model.

[0115] Step S422: Calculate the ratio of the middle hole area of ​​the first-level upper anti-sinking ring model and the first-level lower anti-sinking ring model to the larger area of ​​the upper end plate and the lower end plate; if the ratio is less than a ratio threshold, modify the middle hole area so that the ratio of the middle hole area to the corresponding end plate area is greater than or equal to the ratio threshold, thereby obtaining a second-level upper anti-sinking ring model and a second-level lower anti-sinking ring model;

[0116] In implementation, the ratio threshold is based on clinical bone ingrowth efficiency research, and preferably, it is 0.3; if the ratio of the middle hole area in the first-level anti-subsidence ring model to the larger area of ​​the upper end plate and the lower end plate is less than the ratio threshold, the outer diameter of the anti-subsidence ring is kept unchanged, and the inner diameter of the anti-subsidence ring is increased according to concentric circles. Preferably, the step size is increased by 0.1 mm / time, and the ratio of the middle hole area in the first-level anti-subsidence ring model to the corresponding end plate area is recalculated after each expansion until it is greater than or equal to the ratio threshold of 0.3, thereby obtaining a second-level anti-subsidence ring model.

[0117] It is understandable that if the area of ​​the middle hole is too small, the contact range between the cancellous bone particles inside the titanium cage skeleton body 1 and the end plate will be reduced, affecting the postoperative bone graft fusion effect.

[0118] Step S423, detecting a sudden change region in the secondary upper anti-sinking ring model and the secondary lower anti-sinking ring model where the curvature is greater than a curvature threshold;

[0119] In the implementation, a 0.5mm×0.5mm grid is divided on the surface of the secondary anti-sinking ring model, and the average curvature q of each node is calculated; the curvature mutation area is defined as the curvature difference Δq between adjacent nodes is greater than 0.5mm. -1 ; Mark all mutation areas and generate curvature-corrected heatmaps.

[0120] Step S424, performing curvature correction on the sudden change region so that the corrected curvature is less than or equal to the curvature threshold, thereby obtaining the upper anti-sinking ring model and the lower anti-sinking ring model;

[0121] In the implementation, the Laplace operator smoothing algorithm (10 iterations, smoothing factor 0.7) was used for the mutation area, forcing the curvature gradient change rate to be ≤0.5mm. -1 , and obtain the three-level anti-sinking ring model.

[0122] It can be understood that limiting and correcting the curvature of the anti-subsidence ring model surface through the curvature threshold can prevent the anti-subsidence ring curvature mutation area from having a cutting effect on the end plate cartilage during implantation; and performing weighted averaging of the surface vertices through the Laplace operator can eliminate local curvature mutations while retaining its matching with the end plate anatomical morphology to the greatest extent.

[0123] Step S43, constructing an upper connecting portion model based on the upper ear-shaped fixing plate model and the upper anti-sinking ring model, and constructing a lower connecting portion model based on the lower ear-shaped fixing plate model and the lower anti-sinking ring model;

[0124] Step S44, constructing a titanium cage skeleton main body model according to the upper anti-sinking ring model and the lower anti-sinking ring model;

[0125] Step S45, connecting and merging the upper anti-sinking ring model, the lower anti-sinking ring model, the upper ear-shaped fixing plate model, the lower ear-shaped fixing plate model, the upper connecting part model, the lower connecting part model and the titanium cage skeleton main body model to obtain the primary structure model.

[0126] Step S5, performing ACCF simulation installation using the primary structure model, and adjusting the primary structure model based on the cervical vertebra installation model after the simulated installation and the model correction parameters to obtain a secondary structure model;

[0127] Specifically, see Figure 2 As shown, it is a cross-sectional schematic diagram of the anterior cervical titanium cage during simulated installation of the present invention, and the step S5 includes:

[0128] Step S51, simulating the internal fixation installation of ACCF surgery, placing the upper anti-sinking ring model, the lower anti-sinking ring model, and the titanium cage skeleton main body model in the primary structure model into a decompression groove, so that the anti-sinking ring fits with the corresponding cervical vertebral endplate, and then fixing the ear-shaped fixation plate model to the surface of the corresponding cervical vertebra 4 with screws 5 to complete the ACCF simulation installation, wherein the decompression groove is obtained by simulating the resection of the target cervical vertebra of the target object through ACCF;

[0129] Specifically, in step S51, when the upper anti-sinking ring model, the lower anti-sinking ring model and the titanium cage skeleton main body model in the primary structure model are placed in the decompression groove, the simulated normal contact stresses of the upper anti-sinking ring model and the lower anti-sinking ring model with the cervical vertebral end plate are respectively obtained in real time. If the simulated normal contact stress is greater than the stress safety threshold, the curvature of the corresponding anti-sinking ring is corrected so that the simulated normal contact stress between the corrected anti-sinking ring and the cervical vertebral end plate during the implantation process is less than or equal to the stress safety threshold.

[0130] During implementation, the primary structure model and the cervical subtotal resection model data were imported into ANSYS software, and the ANSYS Explicit Dynamics module was used to simulate the installation part of the ACCF procedure. Preferably, the titanium cage implantation speed was set to 2 mm / s to simulate the intraoperative percussion implantation process. The normal contact force between the anti-sinking ring and the end plate contact surface was monitored in real time. When the normal contact force was greater than the stress safety threshold, an early warning was triggered and the interference position was recorded. The stress safety threshold was based on the safety threshold of the orthopedic percussion instrument and was preferably 50 N.

[0131] In practice, the position of the interference area of ​​the anti-sinking ring and its curvature data were extracted and imported into Solidwork software. The primary structure model was modified to reduce the curvature of the interference area of ​​the anti-sinking ring. The calculation formula for the curvature reduction is as follows:

[0132] q 减小 =k×(F max -F);

[0133] Among them, q 减小 is the curvature reduction, in mm -1 ; k is the interference adjustment coefficient, preferably, it is 0.1; F max is the peak value of the normal contact force at the interference position, in N; F is the stress safety threshold, which is 50N;

[0134] The implantation process is re-simulated until the normal contact stress between the anti-sinking ring and the cervical vertebral end plate during the implantation process is always less than or equal to the stress safety threshold.

[0135] It can be understood that the curvature correction amount at the interference position increases with the severity of the interference to avoid excessive correction that causes a decrease in the fit between the anti-sinking ring and the end plate.

[0136] Step S52, determine whether the contact area of ​​the end plates corresponding to the upper anti-sinking ring model and the lower anti-sinking ring model in the primary structure model and the cervical vertebra 4 in each partition is less than the corresponding contact area threshold; if the contact area is less than the corresponding contact area threshold, correct the surface of the corresponding partition of the corresponding anti-sinking ring so that the contact area is greater than or equal to the contact area threshold to obtain the secondary structure model.

[0137] During implementation, the projection area of ​​the curved surface of the anti-sinking ring on each partition of the corresponding cervical vertebral end plate is determined. When the projection area is greater than or equal to 50% of the area of ​​the partition, the partition is determined to be an effective contact partition; it is determined whether the contact area between the anti-sinking ring and the cervical vertebral end plate in each effective contact partition is greater than or equal to the corresponding contact area threshold; if the contact area is less than the corresponding contact area threshold, the curvature of the curved surface of the corresponding partition of the anti-sinking ring is corrected, and the contact area is recalculated until the contact area is greater than or equal to the contact area threshold; preferably, when the contact area change rate is less than 2% after three consecutive corrections, or the total number of corrections is greater than 10 times, step S52 is terminated and the secondary structure model is output.

[0138] Step S6, manufacturing an anterior cervical titanium cage for the target subject based on the secondary structure model;

[0139] During implementation, a laser selective melting 3D printer was used for processing and manufacturing to obtain an anterior cervical titanium cage for the target object.

[0140] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method for adaptively manufacturing anterior cervical titanium cage, characterized in that: include: Step S1, obtaining cervical spine CT data of the target object; Step S2, performing three-dimensional reconstruction on the cervical vertebrae CT data to obtain a complete three-dimensional vertebrae model, and analyzing the cervical vertebrae CT data and the complete three-dimensional vertebrae model to obtain model correction parameters; Step S3, performing ACCF simulated resection on the three-dimensional vertebral model based on the expected resection amount of the target cervical vertebra of the target object, to obtain a cervical subtotal resection model after simulated resection; Step S4, obtaining a primary structural model of anterior cervical titanium cage based on the subtotal cervical vertebra resection model and the model correction parameters; Step S5, performing ACCF simulation installation using the primary structure model, and adjusting the primary structure model based on the cervical vertebra installation model after the simulated installation and the model correction parameters to obtain a secondary structure model; Step S6, manufacturing an anterior cervical titanium cage for the target subject based on the secondary structure model; The anterior cervical titanium cage includes a titanium cage frame body, anti-sinking rings arranged at both ends of the titanium cage frame body and in contact with the cervical vertebral end plates, and ear-shaped fixing parts arranged at both ends of the titanium cage frame body.

2. The adaptive manufacturing method of the anterior cervical titanium cage according to claim 1 is characterized in that: The anterior cervical titanium cage comprises: The anti-sinking ring is a hollow ring structure whose surface is in contact with the bony endplate of the cervical vertebra. The anti-sinking ring includes an upper anti-sinking ring and a lower anti-sinking ring. The upper surface of the upper anti-sinking ring is in contact with the curved surface of the lower endplate of the bony endplate of the upper adjacent cervical vertebra, and the lower surface of the lower anti-sinking ring is in contact with the curved surface of the upper endplate of the bony endplate of the lower adjacent cervical vertebra. The titanium cage skeleton body is a hollow columnar structure with mesh holes, the upper end of the titanium cage skeleton body is connected to the upper anti-sinking ring, and the lower end of the titanium cage skeleton body is connected to the lower anti-sinking ring; The ear-shaped fixing portion includes an ear-shaped fixing plate and a connecting area, wherein the ear-shaped fixing plate includes an upper ear-shaped fixing plate and a lower ear-shaped fixing plate respectively provided with a screw hole and a semicircular weight-reducing groove, and the connecting area includes an upper connecting area and a lower connecting area, the upper ear-shaped fixing plate is connected to the upper anti-sinking ring through the upper connecting area and is parallel to the vertebral surface of the upper adjacent cervical vertebra, and the lower ear-shaped fixing plate is connected to the lower anti-sinking ring through the lower connecting area and is parallel to the vertebral surface of the lower adjacent cervical vertebra; The anti-sinking ring, the titanium cage skeleton body, the connecting area and the ear-shaped fixing plate are integrally fixedly connected.

3. The adaptive manufacturing method of the anterior cervical titanium cage according to claim 2, characterized in that: The step S2 comprises: Step S21, importing the cervical vertebra CT data into a medical imaging control system for three-dimensional reconstruction and segmenting the vertebrae to obtain six separate vertebral body models of C2 to C7; Step S22, importing each of the split cervical vertebrae models into reverse engineering software for model optimization and conversion into a solid model; Step S23, importing each of the solid models into a three-dimensional design software to generate cancellous bone, cortical bone, bony endplate, posterior structure, intervertebral disc, and ligament complex, and adjusting the cervical spine posture to the ACCF surgical posture to obtain the complete three-dimensional vertebral body model; Step S24: Analyze the cervical vertebrae CT data and the complete three-dimensional vertebral body model to obtain the model correction parameters.

4. The adaptive manufacturing method of the anterior cervical titanium cage according to claim 3 is characterized in that: The step S24 includes: Step S241, constructing a deformation trajectory of the esophagus during a swallowing cycle based on the cervical spine CT data, and obtaining a minimum spacing distance between the esophageal wall and the front edge of the titanium cage skeleton body; Step S242, obtaining a depth adjustment parameter according to the minimum separation distance and the expected resection amount of the target object; Step S243: Divide the upper end plate and the lower end plate into several partitions according to the bone density distribution of the bony end plate, and calculate the contact area threshold of the anti-sinking ring corresponding to the upper end plate and the lower end plate in each partition.

5. The adaptive manufacturing method of anterior cervical titanium cage according to claim 4, characterized in that: In step S243, the contact area threshold is negatively correlated with the bone density of the bony endplate.

6. The adaptive manufacturing method of anterior cervical titanium cage according to claim 5, characterized in that: The step S4 comprises: Step S41, constructing an upper ear-shaped fixation plate model and a lower ear-shaped fixation plate model based on the vertebral surface of the upper adjacent cervical vertebra and the lower adjacent cervical vertebra close to the esophagus side of the target cervical vertebra; Step S42, constructing an upper anti-sinking ring model based on the lower end plate of the upper adjacent cervical vertebral body of the target cervical vertebral body, and constructing a lower anti-sinking ring model based on the upper end plate of the lower adjacent cervical vertebral body of the target cervical vertebral body; Step S43, constructing an upper connecting portion model based on the upper ear-shaped fixing plate model and the upper anti-sinking ring model, and constructing a lower connecting portion model based on the lower ear-shaped fixing plate model and the lower anti-sinking ring model; Step S44, constructing a titanium cage skeleton main body model according to the upper anti-sinking ring model and the lower anti-sinking ring model; Step S45, connecting and merging the upper anti-sinking ring model, the lower anti-sinking ring model, the upper ear-shaped fixing plate model, the lower ear-shaped fixing plate model, the upper connecting part model, the lower connecting part model and the titanium cage skeleton main body model to obtain the primary structure model.

7. The adaptive manufacturing method of anterior cervical titanium cage according to claim 6, characterized in that: The step S42 includes: Step S421, constructing a first-level upper anti-sinking ring model that is completely fitted with the lower end plate, and a first-level lower anti-sinking ring model that is completely fitted with the upper end plate; Step S422: Calculate the ratio of the middle hole area of ​​the first-level upper anti-sinking ring model and the first-level lower anti-sinking ring model to the larger area of ​​the upper end plate and the lower end plate; if the ratio is less than a ratio threshold, modify the middle hole area so that the ratio of the middle hole area to the corresponding end plate area is greater than or equal to the ratio threshold, thereby obtaining a second-level upper anti-sinking ring model and a second-level lower anti-sinking ring model; Step S423, detecting a sudden change region in the secondary upper anti-sinking ring model and the secondary lower anti-sinking ring model where the curvature is greater than a curvature threshold; Step S424 , performing curvature correction on the sudden change region so that the corrected curvature is less than or equal to the curvature threshold, thereby obtaining the upper anti-sinking ring model and the lower anti-sinking ring model.

8. The adaptive manufacturing method of anterior cervical titanium cage according to claim 7, characterized in that: In step S421, the position of the anti-sinking ring on the corresponding end plate is determined according to the depth adjustment parameter, so that the contour of the sunken area formed by the titanium cage skeleton body and the ear-shaped fixing portion is located outside the envelope surface of the esophageal deformation trajectory.

9. The adaptive manufacturing method of anterior cervical titanium cage according to claim 6, characterized in that: The step S5 comprises: Step S51, simulating the internal fixation installation of ACCF surgery, placing the upper anti-sinking ring model, the lower anti-sinking ring model, and the titanium cage skeleton main body model in the primary structure model into a decompression groove, so that the anti-sinking ring fits with the corresponding cervical vertebral endplate, and then fixing the ear-shaped fixation plate model to the surface of the corresponding cervical vertebra with screws to complete the ACCF simulation installation, wherein the decompression groove is obtained by simulating the resection of the target cervical vertebra of the target object by ACCF; Step S52, determine whether the contact area of ​​the end plates corresponding to the upper anti-sinking ring model and the lower anti-sinking ring model in the primary structure model and the cervical vertebral body in each partition is less than the corresponding contact area threshold; if the contact area is less than the corresponding contact area threshold, correct the surface of the corresponding partition of the corresponding anti-sinking ring so that the contact area is greater than or equal to the contact area threshold to obtain the secondary structure model.

10. The adaptive manufacturing method of anterior cervical titanium cage according to claim 9, characterized in that: In step S51, when the upper anti-sinking ring model, the lower anti-sinking ring model and the titanium cage skeleton main body model in the primary structure model are placed in the decompression groove, the simulated normal contact stresses of the upper anti-sinking ring model and the lower anti-sinking ring model with the cervical vertebral end plate are respectively obtained in real time. If the simulated normal contact stress is greater than the stress safety threshold, the curvature of the corresponding anti-sinking ring is corrected so that the simulated normal contact stress between the corrected anti-sinking ring and the cervical vertebral end plate during the implantation process is less than or equal to the stress safety threshold.

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