An individualized tantalum metal cervical intervertebral fusion cage and a design method thereof

Abstract

The present invention discloses an individualized tantalum metal cervical intervertebral fusion device, which relates to the technical field of spinal implants, and aims to provide an individualized tantalum metal cervical intervertebral fusion device that is conducive to bone growth and bone fusion, and a design method for a cervical intervertebral fusion device that highly matches the individualized human body mechanical properties. The main technical scheme of the present invention is: an individualized tantalum metal cervical intervertebral fusion device, comprising: an upper fusion surface is an arched surface body that bulges upward, a lower fusion surface is an arched surface body that bulges downward, the thickness of the edge of the arched surface body is greater than the thickness of the center of the arched surface body, the edge of the arched surface body, the surrounding area of ​​the arched surface body is evenly distributed with a plurality of through holes in an annular manner, the middle area of ​​the arched surface body is provided with a central hole and a plurality of strip holes surrounding the central hole, and the peripheral side wall is provided with a plurality of bone grafting side holes; the lattice structure is evenly distributed on the inner side surface of the upper fusion surface, the inner side surface of the lower fusion surface and the inner side surface of the peripheral side wall.

Description

Technical Field

[0001] The present invention relates to the technical field of spinal implants, and in particular to an individualized tantalum metal cervical intervertebral fusion cage and a design method thereof. Background Art

[0002] The cervical intervertebral fusion device is a commonly used human implant used to treat spinal diseases such as cervical degenerative lesions and spinal trauma. It is placed in the spinal space after the intervertebral disc is removed during surgery. It can restore normal intervertebral height, correct pathological deformities of the spine, and promote bony fusion of upper and lower vertebrae.

[0003] At present, the types of commonly used cervical intervertebral fusion devices can be divided into two categories: metal type and non-metal type. These two types of intervertebral fusion devices have their own advantages. The most mature metal type cervical intervertebral fusion devices are those made of titanium alloy. Their advantage is good mechanical stability. However, metal type cervical intervertebral fusion devices generally have too high elastic modulus, which is not matched with normal bone tissue. After implantation in the intervertebral space, they are prone to serious stress shielding effect, and are prone to problems such as device settlement, displacement or vertebral fracture. In addition, titanium alloy has poor biological activity and cannot fuse with the bone interface. The representative of non-metallic intervertebral fusion devices is the intervertebral fusion device made of polyetheretherketone, which has the advantages of being X-ray transparent and having an elastic modulus close to that of bone tissue. However, polyetheretherketone is a biologically inert material. After implantation in the human body, the fusion device is gradually wrapped by fibrous tissue and cannot fuse with the bone interface, resulting in settlement or displacement caused by micro-movement of the fusion device in the later stage of implantation.

[0004] Application No. CN201710000029.3 discloses a porous titanium intervertebral fusion cage, which consists of two parts: a support structure and a porous structure, which are fixedly connected to each other in an integral form. The support part is used to bear the load, and the porous part is used to guide the growth of new bone. The support structure only accounts for 10% of the total volume of the cage. Although it provides a larger bone growth space, no bone grafting space is reserved. Summary of the invention

[0005] In view of this, the present invention provides an individualized tantalum metal cervical intervertebral fusion device and a design method thereof, the main purpose of which is to provide a tantalum metal cervical intervertebral fusion device that is conducive to bone growth and bone fusion, and a design method of a tantalum metal cervical intervertebral fusion device that highly matches the individualized human body mechanical properties.

[0006] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0007] In one aspect, the present invention provides an individualized tantalum metal cervical intervertebral fusion device, which comprises: a shell portion and a lattice structure;

[0008] The shell part includes an upper fusion surface, a lower fusion surface and a peripheral side wall, wherein the upper fusion surface is an upwardly convex arched surface body matching the shape of the lower surface of the upper vertebral body, and the lower fusion surface is a downwardly convex arched surface body matching the shape of the upper surface of the lower vertebral body, the thickness of the edge of the arched surface body is greater than the thickness of the center of the arched surface body, a plurality of through holes are evenly distributed in an annular manner around the arched surface body, a central hole and a plurality of strip holes surrounding the central hole are provided in the middle area of ​​the arched surface body, and a plurality of bone grafting side holes are provided on the peripheral side wall;

[0009] The lattice structure is evenly distributed on the inner side surface of the upper fusion surface, the inner side surface of the lower fusion surface and the inner side surface of the peripheral side wall.

[0010] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0011] Optionally, the bone graft side hole includes a first bone graft side hole and a second bone graft side hole, the first bone graft side hole is located on the front side of the peripheral side wall, and the second bone graft side hole is located on the left side and the right side of the peripheral side wall.

[0012] Optionally, the outer side surface of the upper fusion surface and the outer side surface of the lower fusion surface are respectively provided with a plurality of prisms arranged in a matrix.

[0013] Optionally, the lattice structure is in a grid shape, and is used to form holes on the inner side surface of the upper fusion surface, the inner side surface of the lower fusion surface, and the inner side surface of the peripheral side wall.

[0014] Optionally, the pore size of the hole is 400 microns.

[0015] Optionally, the upper fusion surface, the lower fusion surface, the peripheral side wall and the lattice structure are all made of metal tantalum.

[0016] On the other hand, the present invention also provides a method for designing an individualized tantalum metal cervical intervertebral fusion cage, which comprises the following steps:

[0017] Step 1: Raw data collection: Use CT to scan the spinal tissue around the patient's affected area, with a scanning layer thickness of less than 1 mm, and output the scanned data in DICOM format;

[0018] Step 2: Reconstruction of the patient's vertebral body 3D model: Import the obtained DICOM format file into the medical image processing software, extract the CT data with a threshold range of 226 to 3070, repair, segment, and construct a 3D model of the diseased intervertebral disc and its adjacent vertebrae, and export the STL format model;

[0019] Step 3, STL model repair: import the vertebral model in STL format into the reverse engineering software, diagnose and repair the model, save it in STEP format, and obtain the adjacent vertebral model with the diseased intervertebral disc removed;

[0020] Step 4, individualized design of the geometric shape of the tantalum metal cervical intervertebral fusion device: import the STEP format file into the 3D CAD software, and use Boolean operation to obtain the upper and lower fusion surface shapes of the tantalum metal cervical intervertebral fusion device to which the upper and lower fusion surfaces of the tantalum metal cervical intervertebral fusion device to be implanted fit, and the lateral wall height of the tantalum metal cervical intervertebral fusion device is obtained by individualized design based on the preoperative CT scan data of the patient and the orthopedic needs, and the obtained initial model of the tantalum metal cervical intervertebral fusion device is saved in the original format;

[0021] Step 5: Obtain biomechanical data: Find a C3D file with similar height and weight to the patient in the C3D database. Import the C3D file into the anybody human body modeling simulation analysis software to perform inverse dynamics simulation. The specific steps are:

[0022] 1) Input the C3D file into the input folder and change the C3D file name to C3D(P);

[0023] 2) Set the body height, weight and other parameters, and adjust the body posture to be consistent with the direction of C3D (P) data;

[0024] 3) Set the mark points in the model to fit the mark points in the C3D(P) data, perform motion and parameter optimization operations, and obtain a txt file containing motion parameters, mark point positions, and action information;

[0025] 4) Perform inverse dynamics simulation on the txt file obtained above to obtain the joint force, muscle force and other data of the required spine parts;

[0026] Step 6, topology optimization of the tantalum metal cervical intervertebral fusion device model: import the initial model of the tantalum metal cervical intervertebral fusion device obtained in step 4 into Altair Inspire, and import the adjacent vertebral model with the diseased intervertebral disc removed obtained in step 3, and assemble the initial model of the tantalum metal cervical intervertebral fusion device with the adjacent vertebral model. Use the joint force obtained in step 5 as the load applied during the topology optimization process, reduce the solid volume of the initial model of the tantalum metal cervical intervertebral fusion device while ensuring the stiffness, and the solid volume accounts for 10% to 20% of the total volume, perform topology optimization, and obtain the mid-term model of the tantalum metal cervical intervertebral fusion device;

[0027] Step 7, design of the internal lattice structure of the tantalum metal cervical intervertebral fusion device: the lattice structure is designed by using three-dimensional CAD drawing software, and the lattice structure is designed inside the intermediate model of the tantalum metal cervical intervertebral fusion device obtained in step 6 to obtain the late model of the tantalum metal cervical intervertebral fusion device;

[0028] Step 8: Integrated finite element analysis and design of the internal fixation system:

[0029] 1) Draw the bone plate system model in 3D CAD drawing software;

[0030] 2) Assemble the bone plate system model, the adjacent vertebral body model obtained in step 3, and the later stage model of the tantalum metal cervical intervertebral fusion device together, and set the mechanical boundary conditions according to the joint force obtained in step 5;

[0031] The density of the lattice structure is optimized according to the results of finite element analysis. The local stiffness and yield strength can be changed by changing the density of the lattice. The final model of the tantalum metal cervical intervertebral fusion cage is obtained by adjusting the appropriate lattice density to match the elastic modulus of the human spine.

[0032] Step nine, 3D printing preparation of tantalum metal cervical intervertebral fusion cage: import the final model of tantalum metal cervical intervertebral fusion cage into SLM printer for printing and post-processing, and use it for clinical application after disinfection and sterilization.

[0033] By means of the above technical solution, the present invention has at least the following advantages:

[0034] When a doctor performs surgery on a patient, he or she can fill the patient's autologous bone graft fragments or other biomaterial particles into the internal space of the shell part through the multiple bone graft side holes;

[0035] When the shell portion is placed between adjacent vertebral endplates, autologous bone cells can fission and grow through the central hole, multiple strip holes and multiple through holes, contact the surface of the adjacent vertebral endplates, and achieve bony fusion of the tantalum metal cervical intervertebral fusion cage and the adjacent vertebral endplates.

[0036] The upper fusion surface and the lower fusion surface are evenly distributed with through holes, center holes and strip holes, respectively, which reduces the rigidity of the fusion device. In addition, both the upper fusion surface and the lower fusion surface adopt an arched surface structure with an edge thickness greater than the center thickness, which, on the one hand, increases the volume inside the shell portion; on the other hand, the surface shape of the upper convex arched surface is more adapted to the surface shape of the upper vertebral end plate, and the surface shape of the lower concave arched surface is more adapted to the surface shape of the lower vertebral end plate; on the other hand, the arc-shaped arched surface design makes the elastic modulus of the upper fusion surface and the lower fusion surface change with the change of thickness, so that the tantalum metal cervical intervertebral fusion device matches the human skeleton.

[0037] The lattice structure is evenly distributed on the inner side surface of the upper fusion surface, the inner side surface of the lower fusion surface and the inner side surface of the circumferential wall. The lattice structure is arranged in a variable density manner. This structure imitates the structure of a natural vertebra in order to match the stress conditions of different positions of a tantalum metal cervical intervertebral fusion device. By changing the density of the lattice, different mechanical properties can be obtained, so that the mechanical properties of the fusion device can be matched with those of a natural vertebra. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A front view of an individualized tantalum metal cervical intervertebral fusion cage provided by an embodiment of the present invention;

[0039] Figure 2 for Figure 1 The view from the AA point in the middle;

[0040] Figure 3 for Figure 1 A magnified view of part B;

[0041] Figure 4 A side view of an individualized tantalum metal cervical intervertebral fusion cage provided by an embodiment of the present invention;

[0042] Figure 5 A top view of an individualized tantalum metal cervical intervertebral fusion cage provided in an embodiment of the present invention;

[0043] Figure 6 A stereoscopic diagram of an individualized tantalum metal cervical intervertebral fusion cage provided by an embodiment of the present invention;

[0044] Figure 7 for Figure 6 Magnified view of part C.

[0045] The reference numerals in the drawings of the specification include: upper fusion surface 1, lower fusion surface 2, peripheral side wall 3, through hole 4, central hole 5, strip hole 6, bone graft side hole 7, first bone graft side hole 701, second bone graft side hole 702, prism 8, hole 9. DETAILED DESCRIPTION

[0046] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0048] like Figure 1 , Figure 2 , Figure 3 , Figure 5 , Figure 6 As shown, an embodiment of the present invention provides an individualized tantalum metal cervical intervertebral fusion device, which includes: a shell portion and a lattice structure;

[0049] The shell portion includes an upper fusion surface 1, a lower fusion surface 2 and a peripheral side wall 3, wherein the upper fusion surface 1 is an upwardly convex arched surface body matching the lower surface shape of the upper vertebral body, and the lower fusion surface 2 is a downwardly convex arched surface body matching the upper surface shape of the lower vertebral body, the thickness of the edge of the arched surface body is greater than the thickness of the center of the arched surface body, a plurality of through holes 4 are evenly distributed in an annular manner around the arched surface body, a central hole 5 and a plurality of strip holes 6 surrounding the central hole 5 are provided in the middle area of ​​the arched surface body, and a plurality of bone grafting side holes 7 are provided on the peripheral side wall 3;

[0050] The lattice structure is evenly distributed on the inner side surface of the upper fusion surface 1 , the inner side surface of the lower fusion surface 2 , and the inner side surface of the peripheral side wall 3 .

[0051] The working process of the personalized tantalum metal cervical interbody fusion cage is as follows:

[0052] When the doctor performs surgery on the patient, the patient's autologous bone graft fragments or other biomaterial particles can be filled into the internal space of the shell part through the multiple bone graft side holes 7;

[0053] When the shell portion is placed between adjacent vertebral endplates, autologous bone cells can fission and grow through the central hole 5, the multiple strip holes 6 and the multiple through holes 4, contact the surface of the adjacent vertebral endplates, and achieve bony fusion of the tantalum metal cervical intervertebral fusion cage and the adjacent vertebral endplates.

[0054] The upper fusion surface 1 and the lower fusion surface 2 are evenly distributed with through holes 4, central holes 5 and strip holes 6, respectively, which reduces the rigidity of the fusion device. Moreover, both the upper fusion surface 1 and the lower fusion surface 2 adopt an arched surface structure in which the edge thickness is greater than the center thickness. On the one hand, the volume inside the shell portion is increased; on the other hand, the surface shape of the upper convex arched surface is more adapted to the surface shape of the upper vertebral end plate, and the surface shape of the lower concave arched surface is more adapted to the surface shape of the lower vertebral end plate; on the other hand, the arc-shaped arched surface design makes the elastic modulus of the upper fusion surface 1 and the lower fusion surface 2 change with the change of thickness, so that the tantalum metal cervical intervertebral fusion device matches the human skeleton.

[0055] The lattice structure is evenly distributed on the inner side surface of the upper fusion surface 1, the inner side surface of the lower fusion surface 2 and the inner side surface of the circumferential wall 3. The lattice structure is arranged in a variable density manner. This structure imitates the structure of a natural vertebra in order to match the stress conditions of different positions of the tantalum metal cervical intervertebral fusion device. By changing the density of the lattice, different mechanical properties can be obtained to match the mechanical properties of the fusion device with those of the natural vertebra.

[0056] In the technical solution of the present invention, the tantalum metal cervical intervertebral fusion device is conducive to the filling and implantation of autologous bone, and is convenient for promoting the bone fusion progress of the fusion device and the upper and lower vertebral bodies.

[0057] Specifically, after the tantalum metal cervical intervertebral fusion device is implanted in the human body, the device mainly bears the pressure from the upper vertebral endplate and the lower vertebral endplate. The single hole diameter of the central hole 5 and the strip hole 6 is relatively large, which is conducive to the early fission and growth of autologous bone cells; the single hole diameter of the multiple through holes 4 in the surrounding area is relatively small, and as the autologous bone cells grow and spread outward through the multiple through holes 4 in the surrounding area, the bone fusion between the tantalum metal cervical intervertebral fusion device and the upper and lower vertebral endplates can be more fully strengthened.

[0058] Specifically, the bone grafting side hole 7 is located on the circumferential side wall 3 of the tantalum metal cervical intervertebral fusion device, which is different from the current common design where the bone grafting holes are located on the upper and lower fusion surfaces 2. The bone grafting side hole 7 of this design can allow the transplanted bone in the fusion device to be vascularized, thereby improving the bone fusion effect of the tantalum metal cervical intervertebral fusion device.

[0059] Specifically, the lattice structure is located on the inner surface of the tantalum metal cervical intervertebral fusion device, so as to prevent the lattice structure from damaging and stimulating the surrounding nerve tissue after the tantalum metal cervical intervertebral fusion device is implanted into the human body.

[0060] Specifically, the edge of the upper fusion surface 1 is fixedly connected to the upper edge of the peripheral side wall 3 , and the edge of the lower fusion surface 2 is fixedly connected to the lower edge of the peripheral side wall 3 .

[0061] like Figure 2 , Figure 4 and Figure 6 As shown, in a specific embodiment, the bone graft side hole 7 includes a first bone graft side hole 701 and a second bone graft side hole 702, the first bone graft side hole 701 is located on the front side of the peripheral side wall 3, and the second bone graft side hole 702 is located on the left and right sides of the peripheral side wall 3.

[0062] In this embodiment, specifically, the rear side of the peripheral side wall 3 faces the spinal nerves. Due to the obstruction of the rear side of the peripheral side wall 3, the growing autologous bone will not contact the spinal nerves, thereby preventing the spinal nerves from being squeezed and stimulated by the growing autologous bone.

[0063] like Figure 2 , Figure 6 , Figure 7 As shown, in a specific embodiment, the outer side surface of the upper fusion surface 1 and the outer side surface of the lower fusion surface 2 are respectively arranged with a plurality of prisms 8 in a matrix.

[0064] In this embodiment, specifically, the outer side entity portion of the upper fusion surface 1 and the outer side entity portion of the lower fusion surface 2 are respectively arranged with a plurality of prisms 8 in a matrix, and the plurality of prisms 8 are respectively inserted into the vertebral endplate to a certain depth to avoid displacement of the installed tantalum metal cervical intervertebral fusion device and ensure the stability of the tantalum metal cervical intervertebral fusion device.

[0065] like Figure 2 , Figure 6 , Figure 7 As shown, in a specific embodiment, the lattice structure is in a grid shape, and is used to form holes 9 on the inner side surface of the upper fusion surface 1 , the inner side surface of the lower fusion surface 2 , and the inner side surface of the peripheral side wall 3 .

[0066] In this embodiment, specifically, autologous bone cells can adhere to and grow into the holes 9. In addition, the lattice structure has a siphon effect, which can promote the exchange of nutrients and improve the bone fusion rate.

[0067] In a specific embodiment, the hole 9 has a diameter of 400 micrometers.

[0068] In this embodiment, the holes 9 with a pore size of 400 microns have a sufficient adsorption surface area to ensure that enough bone cells can be adsorbed therein without reducing the rigidity of the tantalum metal cervical intervertebral fusion device too much.

[0069] In a specific implementation, the upper fusion surface 1, the lower fusion surface 2, the peripheral side wall 3 and the lattice structure are all made of metal tantalum.

[0070] In this embodiment, specifically, since tantalum metal has good biocompatibility, biomechanical properties similar to those of bones, and good biological activity capable of fusing with bones, the tantalum metal cervical intervertebral fusion device is made entirely of tantalum metal.

[0071] On the other hand, another embodiment of the present invention further provides a method for designing an individualized tantalum metal cervical intervertebral fusion cage, which comprises the following steps:

[0072] Step 1: Raw data collection: Use CT to scan the spinal tissue around the patient's affected area, with a scanning layer thickness of less than 1 mm, and output the scanned data in DICOM format;

[0073] Step 2: Reconstruction of the patient's vertebral body 3D model: Import the obtained DICOM format file into the medical image processing software, extract the CT data with a threshold range of 226 to 3070, repair, segment, and construct a 3D model of the diseased intervertebral disc and its adjacent vertebrae, and export the STL format model;

[0074] Step 3, STL model repair: import the vertebral model in STL format into the reverse engineering software, diagnose and repair the model, save it in STEP format, and obtain the adjacent vertebral model with the diseased intervertebral disc removed;

[0075] Step 4, individualized design of the geometric shape of the tantalum metal cervical intervertebral fusion device: import the STEP format file into the 3D CAD software, and use Boolean operation to obtain the upper and lower fusion surface shapes of the tantalum metal cervical intervertebral fusion device to which the upper and lower fusion surfaces of the tantalum metal cervical intervertebral fusion device to be implanted fit, and the lateral wall height of the tantalum metal cervical intervertebral fusion device is obtained by individualized design based on the preoperative CT scan data of the patient and the orthopedic needs, and the obtained initial model of the tantalum metal cervical intervertebral fusion device is saved in the original format;

[0076] Step 5: Obtain biomechanical data: Find a C3D file with similar height and weight to the patient in the C3D database. Import the C3D file into the anybody human body modeling simulation analysis software to perform inverse dynamics simulation. The specific steps are:

[0077] 1) Input the C3D file into the input folder and change the C3D file name to C3D(P);

[0078] 2) Set the body height, weight and other parameters, and adjust the body posture to be consistent with the direction of C3D (P) data;

[0079] 3) Set the mark points in the model to fit the mark points in the C3D(P) data, perform motion and parameter optimization operations, and obtain a txt file containing motion parameters, mark point positions, and action information;

[0080] 4) Perform inverse dynamics simulation on the txt file obtained above to obtain the joint force, muscle force and other data of the required spine parts;

[0081] Step 6, topology optimization of the tantalum metal cervical intervertebral fusion device model: import the initial model of the tantalum metal cervical intervertebral fusion device obtained in step 4 into Altair Inspire, and import the adjacent vertebral model with the diseased intervertebral disc removed obtained in step 3, and assemble the initial model of the tantalum metal cervical intervertebral fusion device with the adjacent vertebral model. Use the joint force obtained in step 5 as the load applied during the topology optimization process, reduce the solid volume of the initial model of the tantalum metal cervical intervertebral fusion device while ensuring the stiffness, and the solid volume accounts for 10% to 20% of the total volume, perform topology optimization, and obtain the mid-term model of the tantalum metal cervical intervertebral fusion device;

[0082] Step 7, design of the internal lattice structure of the tantalum metal cervical intervertebral fusion device: the lattice structure is designed by using three-dimensional CAD drawing software, and the lattice structure is designed inside the intermediate model of the tantalum metal cervical intervertebral fusion device obtained in step 6 to obtain the late model of the tantalum metal cervical intervertebral fusion device;

[0083] Step 8: Integrated finite element analysis and design of the internal fixation system:

[0084] 1) Draw the bone plate system model in 3D CAD drawing software;

[0085] 2) Assemble the bone plate system model, the adjacent vertebral body model obtained in step 3, and the later stage model of the tantalum metal cervical intervertebral fusion device together, and set the mechanical boundary conditions according to the joint force obtained in step 5;

[0086] The density of the lattice structure is optimized according to the results of finite element analysis. The local stiffness and yield strength can be changed by changing the density of the lattice. The final model of the tantalum metal cervical intervertebral fusion cage is obtained by adjusting the appropriate lattice density to match the elastic modulus of the human spine.

[0087] Step nine, 3D printing preparation of tantalum metal cervical intervertebral fusion cage: import the final model of tantalum metal cervical intervertebral fusion cage into SLM printer for printing and post-processing, and use it for clinical application after disinfection and sterilization.

[0088] The above method is a design method for a tantalum cervical tantalum metal cervical intervertebral fusion device that is individually designed using 3D printing technology, has a lattice structure, and highly matches the mechanical properties of the human body. It is designed and prepared using surface cold spraying technology, reverse engineering, computer-aided design, biomechanical analysis, topological optimization, finite element analysis, mechanical experiments, metal 3D printing and other methods. The advantages of the present invention are reflected in the following four aspects:

[0089] First, the tantalum metal cervical intervertebral fusion device of the present invention has excellent biocompatibility, bioactivity and osteoinductivity, which is specifically manifested in two aspects:

[0090] (1) The integrated design of materials, structure and function is used to jointly improve the fusion effect of tantalum metal cervical intervertebral fusion device: Tantalum is used as the raw material. This metal has excellent biomechanical properties, biocompatibility and osteoinductive activity, and other basic properties suitable for use as a human implant material. The lattice structure is used to design pores on the inner surface of the tantalum metal cervical intervertebral fusion device that can promote the proliferation and differentiation of osteoblasts, further improving the fusion effect.

[0091] (2) Maximize the reserved bone graft space and improve the effective use of the fusion surface space: The upper and lower fusion surfaces of the fusion device are designed to have a gradient change in thickness that gradually decreases from the outside to the inside. The purpose is to reduce the elastic modulus of the metal structure and increase the bone graft space inside the fusion device; the fusion device is covered with smaller through holes around it, and bone cells can grow into them, so that the bone tissue and it are integrated. Designing a larger through hole in the center of the fusion surface is conducive to the growth of the autologous bone filled from the inside to the outside of the fusion device and the exchange of nutrients, promoting the bony fusion of the upper and lower surfaces of the fusion device. And designing larger side holes is conducive to the establishment of blood supply between the bone graft material and the surrounding soft tissue, and promoting the growth of transplanted bone.

[0092] Second, the personalized tantalum metal cervical intervertebral fusion device of the present invention can achieve rigidity and compressive strength that are precisely matched to the patient's vertebral body. Considering the different usage locations and surgical methods of the tantalum metal cervical intervertebral fusion device, a bone plate system is sometimes used to fix the implanted tantalum metal cervical intervertebral fusion device. The present invention is customized according to the two different usage scenarios with or without a bone plate system, specifically:

[0093] (1) Precise customization of the mechanical properties of tantalum metal cervical intervertebral fusion devices that do not require bone plates: Due to differences in individual factors and the location of the affected area, each patient has different requirements for the compressive strength of tantalum metal cervical intervertebral fusion devices. The present invention uses inverse dynamics simulation technology to obtain the stress conditions of the patient's affected intervertebral disc, and uses the stress conditions as the basis for structural design. By combining topological optimization with finite element analysis to quantitatively change the structural stiffness and compressive strength, the expected mechanical properties can be achieved. (Since the stiffness of metal materials is much higher than that of human bones, bone tissue is in a state of low stress for a long time. In the later stage of implantation of tantalum metal cervical intervertebral fusion devices into the human body, bone tissue will develop symptoms such as osteoporosis due to insufficient mechanical stimulation. The purpose of stiffness matching is to reduce the "stress shielding" effect; the purpose of compressive strength matching is to reduce the stiffness while ensuring the load-bearing capacity of the tantalum metal cervical intervertebral fusion device to avoid failure after implantation into the human body.)

[0094] (2) Precise customization of the mechanical properties of the tantalum metal cervical intervertebral fusion device used with the bone plate: When the bone plate system is used at the same time, the bone plate system will change the stress of the tantalum metal cervical intervertebral fusion device. In this case, it is necessary to optimize the structure of the tantalum metal cervical intervertebral fusion device used with the bone plate system in order to achieve a precise match with the mechanical properties of the patient's affected vertebrae and reduce the risk of stress shielding, displacement, and sinking.

[0095] Third, the geometric features of the personalized tantalum metal cervical intervertebral fusion device of the present invention match the shape of the contact surface of the upper and lower vertebrae of the patient's affected intervertebral disc: the personalized tantalum metal cervical intervertebral fusion device that conforms to the shape and height of the affected intervertebral disc is "tailored" according to different patients, so that the contour features of the designed tantalum metal cervical intervertebral fusion device are consistent with the contours of the upper and lower vertebral end plates of the patient's affected part, and the spinal morphology is accurately restored. Reduce the risk of sinking and displacement caused by shape and height mismatch.

[0096] Fourth, the existing intervertebral fusion device design methods all use the finite element analysis method, but the setting of the mechanical boundary conditions in the finite element analysis all uses static, single-direction forces, and the magnitude of the force is estimated, which lacks authenticity and accuracy. The present invention utilizes inverse dynamics simulation technology (i.e., using Anybody software to process C3D motion data that conforms to the patient's physical characteristics) to obtain the joint force between the patient's affected vertebrae. This force is dynamic and multi-directional, and is closer to the actual stress condition of the patient's vertebrae. Using the calculated intervertebral joint force as the mechanical boundary condition of the finite element analysis will greatly improve the accuracy of the finite element analysis, so that the designed tantalum metal cervical intervertebral fusion device can match the mechanical properties of the patient's affected vertebrae to the greatest extent.

[0097] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for designing an individualized tantalum metal cervical intervertebral fusion cage, characterized in that: The individualized tantalum metal cervical intervertebral fusion cage comprises the following structure: A shell body, the shell body comprising an upper fusion surface, a lower fusion surface and a peripheral side wall, the upper fusion surface is an upwardly convex arched surface body matching the shape of the lower surface of the upper vertebral body, the lower fusion surface is a downwardly convex arched surface body matching the shape of the upper surface of the lower vertebral body, the thickness of the edge of the arched surface body is greater than the thickness of the center of the arched surface body, a plurality of through holes are evenly distributed in an annular manner around the arched surface body, a central hole and a plurality of strip holes surrounding the central hole are provided in the middle area of ​​the arched surface body, and a plurality of bone grafting side holes are provided on the peripheral side wall; A lattice structure, wherein the lattice structure is evenly distributed on the inner side surface of the upper fusion surface, the inner side surface of the lower fusion surface, and the inner side surface of the peripheral side wall; The lattice structure is in a grid shape and is used to form holes on the inner side surface of the upper fusion surface, the inner side surface of the lower fusion surface and the inner side surface of the peripheral side wall; The steps of the design method of the individualized tantalum metal cervical intervertebral fusion cage are as follows: Step 1: Raw data collection: Use CT to scan the spinal tissue around the patient's affected area, with a scanning layer thickness of less than 1 mm, and output the scanned data in DICOM format; Step 2: Reconstruction of the patient's vertebral body 3D model: Import the obtained DICOM format file into the medical image processing software, extract the CT data with a threshold range of 226 to 3070, repair, segment, and construct a 3D model of the diseased intervertebral disc and its adjacent vertebrae, and export the STL format model; Step 3, STL model repair: import the vertebral model in STL format into the reverse engineering software, diagnose and repair the model, save it in STEP format, and obtain the adjacent vertebral model with the diseased intervertebral disc removed; Step 4, individualized design of the geometric shape of the tantalum metal cervical intervertebral fusion device: import the STEP format file into the 3D CAD software, and use Boolean operation to obtain the upper and lower fusion surface shapes of the tantalum metal cervical intervertebral fusion device to which the upper and lower fusion surfaces of the tantalum metal cervical intervertebral fusion device to be implanted fit, and the lateral wall height of the tantalum metal cervical intervertebral fusion device is obtained by individualized design based on the preoperative CT scan data of the patient and the orthopedic needs, and the obtained initial model of the tantalum metal cervical intervertebral fusion device is saved in the original format; Step 5: Obtain biomechanical data: Find a C3D file with similar height and weight to the patient in the C3D database, import the C3D file into the anybody human body modeling simulation analysis software, and perform inverse dynamics simulation. The specific steps are as follows: 1) Input the C3D file into the input folder and change the C3D file name to C3D (P); 2) Set the body height, weight and other parameters to adjust the body posture to be consistent with the direction of C3D (P) data; 3) Set the mark points in the model to fit the mark points in the C3D (P) data, perform motion and parameter optimization operations, and obtain a txt file containing motion parameters, mark point positions, and action information; 4) Perform inverse dynamics simulation on the txt file obtained above to obtain the required data of joint force, muscle force, etc. of the spine; Step 6, topology optimization of tantalum metal cervical intervertebral fusion device model: import the initial model of tantalum metal cervical intervertebral fusion device obtained in step 4 into Altair Inspire, and import the adjacent vertebral body model with the diseased intervertebral disc removed obtained in step 3, assemble the initial model of tantalum metal cervical intervertebral fusion device with the adjacent vertebral body model, use the joint force obtained in step 5 as the load applied in the topology optimization process, reduce the solid volume of the initial model of tantalum metal cervical intervertebral fusion device while ensuring the stiffness, and the solid volume accounts for 10% to 20% of the total volume, perform topology optimization, and obtain the mid-term model of tantalum metal cervical intervertebral fusion device; Step 7, design of the internal lattice structure of the tantalum metal cervical intervertebral fusion device: the lattice structure is designed by using three-dimensional CAD drawing software, and the lattice structure is designed inside the intermediate model of the tantalum metal cervical intervertebral fusion device obtained in step 6 to obtain the late model of the tantalum metal cervical intervertebral fusion device; Step 8: Integrated finite element analysis and design of the internal fixation system: 1) Draw the bone plate system model in 3D CAD drawing software; 2) Assemble the plate system model, the adjacent vertebral body model obtained in step 3, and the later stage model of the tantalum metal cervical intervertebral fusion device together, and set the mechanical boundary conditions according to the joint force obtained in step 5; The density of the lattice structure is optimized according to the results of finite element analysis. The local stiffness and yield strength can be changed by changing the density of the lattice. The final model of the tantalum metal cervical intervertebral fusion cage is obtained by adjusting the appropriate lattice density to match the elastic modulus of the human spine. Step nine, 3D printing preparation of tantalum metal cervical intervertebral fusion cage: import the final model of tantalum metal cervical intervertebral fusion cage into SLM printer for printing and post-processing, and use it for clinical application after disinfection and sterilization.

2. The method for designing an individualized tantalum metal cervical intervertebral fusion cage according to claim 1, characterized in that: The bone grafting side holes include a first bone grafting side hole and a second bone grafting side hole. The first bone grafting side hole is located on the front side of the peripheral side wall, and the second bone grafting side hole is located on the left side and the right side of the peripheral side wall.

3. The method for designing an individualized tantalum metal cervical intervertebral fusion cage according to claim 1, characterized in that: A plurality of prisms are arranged in a matrix on the outer side surface of the upper fusion surface and the outer side surface of the lower fusion surface.

4. The method for designing an individualized tantalum metal cervical intervertebral fusion cage according to claim 1, characterized in that: The hole diameter is 400 micrometers.

5. The method for designing an individualized tantalum metal cervical intervertebral fusion cage according to any one of claims 1 to 4, characterized in that: The upper fusion surface, the lower fusion surface, the peripheral side wall and the lattice structure are all made of metal tantalum.

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