Porous fusion cage and design device and method

Abstract

The invention discloses a porous fusion cage and a design device and method. The porous fusion cage design device comprises a three-dimensional model acquisition module, a mechanical calculation module, a finite element module and a fusion cage parameter generation module. The three-dimensional model acquisition module is used for acquiring a three-dimensional model of a target area of a target object; the mechanical calculation module is used for calculating muscle and ligament load data of a target area of a target object; the finite element module is used for determining a finite element analysis result according to the three-dimensional model, the fusion cage model and the muscle and ligament load data; and the fusion cage parameter generation module is used for determining the design parameters of the porous fusion cage according to the finite element analysis result. According to the porous fusion cage design device, the overall biomechanical condition of the adjacent vertebral bodies can be comprehensively considered, and the designed porous fusion cage better meets the actual use requirement of a patient.

Description

Technical Field

[0001] The invention relates to a porous fusion device and a design device and method. Background Art

[0002] Fusion devices, such as intervertebral fusion devices, can be used to treat severe disc herniation combined with lumbar spondylolisthesis, spinal stenosis, vertebral instability or severe vertebral deformation, tumor lesions, combined lesions, inflammatory lesions, etc., and have a wide range of applications. However, compared with human intervertebral discs, fusion devices usually have significantly higher stiffness. This high-rigidity structure can easily lead to collapse of the upper and lower vertebral endplates of the fusion device. Especially for patients with osteoporosis, the risk of collapse is higher. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the defect of the prior art that the porous structure of the fusion device and the overall biomechanics of the patient's bones do not match, and to provide a porous fusion device and a design method.

[0004] The present invention greatly solves the above technical problems through the following method: the finite element model used at least includes the upper and lower two vertebrae of the removed intervertebral disc (at least 4 vertebrae in total), the intervertebral disc and the fusion device; the loads of muscles and ligaments in the finite element model are calculated based on the skeletal muscle multibody dynamics model, and the overall model is more complete and accurate, which conforms to the actual mechanical conditions of the patient. The fusion device structure included in the finite element model is similar to the human intervertebral disc (divided into upper and lower end plates and middle layers), divided into three layers of upper, middle and lower layers, and Young's modulus G1, G2, and G3 are respectively assigned in the calculation. Therefore, it is no longer to optimize the Young's modulus of one layer, but to optimize the best combination of G1, G2, and G3. In order to improve the optimization efficiency, the initial reference values ​​of the upper and lower moduli G1 and G3 can be set based on the size of the Young's modulus of the upper and lower vertebral cortex respectively; the initial reference value of the middle layer modulus G2 can be set based on the modulus of the intervertebral disc. G1, G2, and G3 were adjusted within the range of ±30% of their initial reference values, and the corresponding G1, G2, and G3 under the optimal biomechanical conditions were obtained through finite element calculation; then, based on the bone tissue implant model generation method, a porous structure with porosity and pore size corresponding to the modulus was designed.

[0005] The middle layer (middle layer 2) of the fusion device of the present invention adopts a porous structure design with adjustable stiffness, which can achieve stiffness matching the patient's bones. At the same time, the porous structure has large holes, which can be used for bone grafting, and has a wide surface area, which can ensure the combination of bone grafting materials and implants. At the same time, the upper and lower surfaces of the fusion device adopt a large-area irregular porous structure to increase the bone integration rate and reduce sinking.

[0006] The present invention provides a porous fusion device design device, which includes: a three-dimensional model acquisition module, a mechanical calculation module, a finite element module, and a fusion device parameter generation module;

[0007] The three-dimensional model acquisition module is used to acquire a three-dimensional model of a target area of ​​a target object;

[0008] The mechanical calculation module is used to calculate muscle and ligament load data;

[0009] The finite element module is used to determine the finite element analysis result according to the three-dimensional model, the fusion cage model and the muscle and ligament load data;

[0010] The fusion device parameter generation module is used to determine the porous fusion device design parameters according to the finite element analysis results.

[0011] In the present invention, preferably, the three-dimensional model of the target area of ​​the target object includes a model of the intervertebral disc to be removed of the target object, at least two vertebral models above and below the intervertebral disc to be removed of the target object, and at least one intervertebral disc model above and below the intervertebral disc to be removed of the target object.

[0012] The intervertebral disc model generally includes an end plate, an annulus fibrosus and a nucleus pulposus model.

[0013] Those skilled in the art know that the vertebral endplate is a bone plate formed after the ossification of the epiphyseal plates above and below the vertebral body stops during the growth and development of the vertebral body. It is slightly concave, i.e., the bony endplate. The center of the vertebral endplate is still covered by a thin layer of hyaline cartilage, which exists throughout life, i.e., the cartilage endplate. The upper and lower cartilage endplates are connected with the nucleus pulposus and the annulus fibrosus to form the intervertebral disc. The vertebral endplates constitute the upper and lower boundaries of the intervertebral disc, and are located between the cancellous bone and the intervertebral disc in the center of the vertebral body. Unless otherwise specified, the "endplate" in the present invention generally refers to the "vertebral endplate".

[0014] In the present invention, those skilled in the art know that the three-dimensional model of the target area of ​​the target object can generally be obtained through CT data of the target patient. The three-dimensional model of the intervertebral disc can generally be obtained through MR data of the target patient.

[0015] In the present invention, those skilled in the art know that each time a new patient uses it, basic information such as the patient's vertebral body three-dimensional model needs to be input to create a new finite element model. The porous fusion device, as an intervertebral disc implant, needs to be designed according to the patient's physiological parameters. The physiological parameters of each patient are different, and the model is different.

[0016] In the present invention, the upper and lower end plates in the intervertebral disc model may correspond to the upper and lower porous layers of the fusion model; the annulus fibrosus may correspond to the middle porous layer of the fusion model; and the nucleus pulposus corresponds to the bone grafting material in the bone grafting window of the fusion model.

[0017] In the present invention, the term "bone grafting window" can also be called a bone grafting hole.

[0018] In the present invention, the nucleus pulposus can be bone grafting materials such as autologous bone, allogeneic bone or artificial bone.

[0019] In the present invention, preferably, the mechanical calculation module includes a skeletal muscle multi-body dynamics module, and the skeletal muscle multi-body dynamics module is used to calculate muscle and ligament load data according to the three-dimensional model and BMI information of the target object.

[0020] In the present invention, preferably, the finite element module includes a finite element establishment module and a finite element analysis module;

[0021] The finite element establishment module is used to establish a finite element model based on the three-dimensional model, the fusion device model and the muscle and ligament load data; the finite element analysis module is used to perform finite element calculation based on the finite element model to determine the finite element analysis result; the finite element analysis result includes obtaining the Young's modulus of the fusion device model.

[0022] Among them, the finite element model can obtain various parameters such as size and material (related to Young's modulus) according to the three-dimensional model, the fusion device model and the muscle and ligament load data, and analyze the deformation of the model under different predetermined stress conditions (such as the stress conditions of the fusion device model under different postures). Once an ideal result is obtained, the appropriate range of the Young's modulus of the fusion device can be determined.

[0023] Among them, more preferably, the fusion device model includes a first porous plate layer, a second porous plate layer and a third porous plate layer which are stacked; the Young's modulus of the fusion device model includes: Young's modulus G1 corresponding to the first porous plate layer, Young's modulus G2 corresponding to the second porous plate layer and Young's modulus G3 corresponding to the third porous plate layer.

[0024] In particular, the finite element calculation includes respectively determining the initial values ​​G1', G2' and G3' of Young's modulus corresponding to the first porous plate layer, the second porous plate layer and the third porous plate layer of the fusion device model, substituting the initial values ​​G1', G2' and G3' of Young's modulus into the finite element model for iterative calculation to obtain the optimal combination of G1, G2 and G3 corresponding to the optimal biomechanical conditions.

[0025] Among them, more preferably, the finite element module also includes a finite element optimization module; the finite element optimization module is used to optimize the finite element analysis results, including optimizing the combination of G1, G2 and G3, and screening out the best combination of G1, G2 and G3.

[0026] Wherein, the G1' is determined according to the Young's modulus of the vertebral cortex of the intervertebral disc to be removed in the target area of ​​the target object; the G3' is determined according to the Young's modulus of the vertebral cortex of the intervertebral disc to be removed in the target area of ​​the target object; the G2' is determined according to the Young's modulus of the intervertebral disc to be removed in the target area of ​​the target object. The G1, G2, and G3 are preferably adjusted within the range of ±30% of their respective initial values.

[0027] Among them, the combination of targets G1, G2 and G3 is generally the optimal biomechanical condition, which refers to the patient's kinematic (including displacement, angular characteristics) and dynamic (torque, angular velocity, angular acceleration, soft tissue response) state under a normal natural intervertebral disc.

[0028] In the present invention, the method for obtaining the G1', the G2' and the G3' may include the following steps:

[0029] K1: Calculate bone mineral density according to the HU value in the CT data of the target patient;

[0030] Wherein, the calculation formula of the bone mineral density can be:

[0031]

[0032] K2: Young's modulus calculated according to the bone mineral density value;

[0033] The calculation formula of the Young's modulus can be:

[0034] E z =-34.7+3230×BMD QCT , (MPa); E x =E y =0.333E z ,(MPa).

[0035] In the present invention, preferably, the porous fusion device design parameters include the porosity and pore size of the porous structure.

[0036] In the present invention, preferably, the method of determining the design parameters of the porous fusion device includes, according to the Young's modulus of the fusion device model in the finite element analysis result, determining the porosity and pore size corresponding to the Young's modulus.

[0037] In the present invention, preferably, the porous fusion device design apparatus further comprises a fusion device design module, and the fusion device design module is used to design a corresponding porous structure model according to the porous fusion device design parameters to obtain a target porous fusion device structure. More preferably, after the step of designing the corresponding porous structure model, the three layers of porous are fused to obtain a target porous fusion device structure.

[0038] More preferably, the porous structure model is obtained according to the bone tissue implant model generation method described in any one of claims 1 to 8 in Chinese patent application CN202210723045.6, or is obtained according to the bone tissue implant model generation device described in claim 11 in Chinese patent application CN202210723045.6.

[0039] More preferably, the method for generating the porous structure model comprises the following steps:

[0040] Obtain a native bone model of the site to be implanted;

[0041] dividing the native bone model into native bone units;

[0042] Determining a bionic bone unit corresponding to the native bone unit; matching the bone tissue characteristics of the bionic bone unit with the bone tissue characteristics of the native bone unit;

[0043] A bone tissue implant model of the site to be implanted is generated based on the bionic bone unit.

[0044] In one embodiment, determining the bionic bone unit corresponding to the native bone unit includes:

[0045] According to a preset mapping relationship between the unit parameters of the bionic bone unit and the bone tissue characteristics, the unit parameters of the bionic bone unit are adjusted so that the bone tissue characteristics of the adjusted bionic bone unit match the bone tissue characteristics of the native bone unit;

[0046] The bionic bone unit is determined according to the adjusted unit parameters of the bionic bone unit.

[0047] In one embodiment, the bone tissue feature of the bionic bone unit includes a first bone tissue feature and a second bone tissue feature, and the unit parameters of the bionic bone unit include a first unit parameter and a second unit parameter; and adjusting the unit parameters of the bionic bone unit according to a preset mapping relationship between the unit parameters of the bionic bone unit and the bone tissue feature so that the adjusted bone tissue feature of the bionic bone unit matches the bone tissue feature of the native bone unit, comprises:

[0048] According to the mapping relationship, the first unit parameter and the second unit parameter of the bionic bone unit are adjusted so that the first bone tissue feature and the second bone tissue feature of the adjusted bionic bone unit match the first bone tissue feature and the second bone tissue feature of the native bone unit respectively.

[0049] In one embodiment, the unit parameters of the bionic bone unit further include a third unit parameter; the unit parameters of the bionic bone unit are adjusted according to a preset mapping relationship between the unit parameters of the bionic bone unit and the bone tissue characteristics, so that the bone tissue characteristics of the adjusted bionic bone unit match the bone tissue characteristics of the native bone unit, and further include:

[0050] According to the mapping relationship, the first unit parameter, the second unit parameter and the third unit parameter of the bionic bone unit are adjusted so that the first bone tissue feature and the second bone tissue feature of the adjusted bionic bone unit match the first bone tissue feature and the second bone tissue feature of the native bone unit respectively.

[0051] In one embodiment, the first bone tissue characteristic includes porosity, the second bone tissue characteristic includes spatial elastic modulus; the first unit parameter includes the number of wire rods in the bionic bone unit and / or the wire diameter of the wire rods in the bionic bone unit, the second unit parameter includes the body center position of the bionic bone unit, and the third unit parameter includes the unit cell size of the bionic bone unit.

[0052] In one embodiment, the bionic bone unit comprises at least three screw rods, and the wire diameters of the screw rods in the bionic bone unit are not all equal.

[0053] In one embodiment, the second bone tissue feature at least includes a first feature component, a second feature component and a third feature component, and the first feature component, the second feature component and the third feature component are perpendicular to each other.

[0054] In one embodiment, generating a bone tissue implant model of the site to be implanted according to the bionic bone unit comprises:

[0055] Generating a bionic bone tissue structure of the site to be implanted according to the bionic bone unit;

[0056] According to the defect shape of the site to be implanted, the bionic bone tissue structure is intercepted to obtain a bone tissue implant model of the site to be implanted.

[0057] More preferably, the method for generating the porous structure model can be prepared according to a bone tissue implant model device, and the bone tissue implant model device comprises:

[0058] An acquisition module, used for acquiring a native bone model of a site to be implanted;

[0059] A segmentation module, used for segmenting the native bone model into native bone units;

[0060] A determination module, used to determine the bionic bone unit corresponding to the native bone unit; the bone tissue characteristics of the bionic bone unit match the bone tissue characteristics of the native bone unit;

[0061] A generation module is used to generate a bone tissue implant model of the site to be implanted based on the bionic bone unit.

[0062] The present invention also provides a method for designing a porous fusion device, which comprises the following steps:

[0063] Acquire a three-dimensional model of a target area of ​​a target object;

[0064] Acquiring muscle and ligament load data of a target area of ​​the target object;

[0065] Determining finite element analysis results based on the three-dimensional model, the fusion cage model, and the muscle and ligament load data;

[0066] The design parameters of the porous fusion device are determined according to the finite element analysis results.

[0067] In the present invention, the method for acquiring the three-dimensional model of the target area of ​​the target object may be as described above.

[0068] In the present invention, the method for acquiring the muscle and ligament load data of the target area of ​​the target object may be as described above.

[0069] In the present invention, the fusion device model can be as described above.

[0070] In the present invention, the method for obtaining the finite element analysis results can be as described above.

[0071] In the present invention, the method for designing the porous fusion device can be implemented by using the porous fusion device designing device as described above.

[0072] The present invention also provides a porous fusion device, which is designed by using the porous fusion device design device as described above, or is obtained by executing the porous fusion device design method as described above.

[0073] The present invention also provides a storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the design method as described above.

[0074] The present invention also provides an electronic device, which includes one or more processors and a memory, wherein the memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors perform the steps of the design method as described above.

[0075] The present invention also provides a porous fusion device, which comprises a first porous plate layer 1, a second porous plate layer 2 and a third porous plate layer 3 which are stacked;

[0076] (1) The second porous plate layer 2 is arranged between the first porous plate layer 1 and the third porous plate layer 3;

[0077] The second porous plate layer 2 has a lamellar three-periodic minimal surface porous structure;

[0078] The first porous plate layer 1 and the third porous plate layer 3 have a dense irregular porous structure;

[0079] (2) The first porous plate layer and the third porous plate layer are provided with through bone grafting windows, and the pores among the first porous plate layer, the second porous plate layer and the third porous plate layer are connected;

[0080] Alternatively, the first porous plate layer and the third porous plate layer do not have bone grafting windows, and the pores among the first porous plate layer, the second porous plate layer and the third porous plate layer are not connected.

[0081] In some preferred embodiments of the present invention, the fusion device parameters of the first porous plate layer 1, the second porous plate layer 2 and the third porous plate layer 3 are obtained by using the aforementioned porous fusion device design device.

[0082] In some preferred embodiments of the present invention, the porous structures of the first porous plate layer 1, the second porous plate layer 2 and the third porous plate layer 3 are obtained by using the aforementioned design method of the porous fusion device.

[0083] In the present invention, the first porous plate layer 1 has a first surface facing away from the second porous plate layer 2 and a second surface facing the second porous plate layer 2 .

[0084] In some preferred embodiments of the present invention, the height of the first porous plate layer 1 is 0.5-2 mm, preferably 1-1.5 mm. The height direction of the first porous plate layer 1 is perpendicular to the first surface and the second surface of the first porous plate layer 1 .

[0085] In some preferred embodiments of the present invention, the porosity of the first porous plate layer 1 is 50%-95%, preferably 65%-80%. The porosity of the first porous plate layer 1 refers to the ratio of the pore volume of the first porous plate layer 1 to the volume of the first porous plate layer 1.

[0086] In some preferred embodiments of the present invention, the porosity of the first porous plate layer 1 is evenly distributed in the height direction of the first porous plate layer 1 .

[0087] In some preferred embodiments of the present invention, in the first porous plate layer 1, the pore size of the porous structure is 100-1000 μm, preferably 400-700 μm.

[0088] In some preferred embodiments of the present invention, the modulus of the first porous plate layer 1 is in the range of about 100 MPa-10 GPa, preferably 500 MPa-3 GPa.

[0089] In some preferred embodiments of the present invention, the first porous plate layer 1 has a height of 0.5-2 mm, a porosity of 50%-95%, a pore size of 100-1000 μm, and a modulus range of about 100 MPa-10 GPa. Under these conditions, the first porous plate layer 1 can ensure good bone integration and mechanical properties.

[0090] In some preferred embodiments of the present invention, the first porous plate layer 1 has a height of 1-1.5 mm, a porosity of 65%-80%, a pore size of 400-700 μm, and a modulus of about 500 MPa-3 GPa.

[0091] In some preferred embodiments of the present invention, the first surface of the first porous plate layer 1 has a plurality of first rod-shaped structures 5 protruding in the height direction. The first rod-shaped structures 5 can be embedded in the end plate to achieve stable initial fixation.

[0092] In some preferred embodiments of the present invention, the second surface of the first porous plate layer 1 has a plurality of second rod-shaped structures 6 that are laterally connected to each other. The second rod-shaped structures 6 can improve the strength of the first porous plate layer 1; at the same time, the second rod-shaped structures 6 can be connected to the second porous plate layer 2, thereby improving the connection strength between the second rod-shaped structures 6 and the second porous plate layer 2; and the second rod-shaped structures 6 and the second porous plate layer 2 are connected by pores, allowing bone to grow through them from top to bottom.

[0093] The lateral direction of the first porous plate layer 1 is a direction parallel to the first surface and the second surface of the first porous plate layer 1 .

[0094] In some preferred embodiments of the present invention, the outer peripheral side of the first porous plate layer 1 has a solid structure 7. By providing the solid structure 7 on the outer peripheral side of the first porous plate layer 1, the strength of the first porous plate layer 1 can be improved, and the stimulation of the fusion device to the soft tissue can also be avoided. The solid structure generally refers to a non-porous structure.

[0095] In the present invention, by providing the bone grafting window 9, the fusion speed between the fusion device and the vertebral body can be increased, and the fusion effect can be enhanced.

[0096] In the present invention, the shape and size of the bone graft window 9 are generally not required. Optionally, the area of ​​the bone graft window 9 accounts for 15-50% of the area of ​​the first porous plate layer 1 .

[0097] In some preferred embodiments of the present invention, the side wall surface of the bone graft window 9 has a solid structure 8. By providing the solid structure 8 on the side of the bone graft window 9, the strength of the first porous plate layer 1 can be improved, and the stimulation of the fusion device to the soft tissue can be avoided.

[0098] In some preferred embodiments of the present invention, the first rod-shaped structure 5 disposed on the first surface of the first porous plate layer 1 is higher than the solid structure 7 disposed on the outer peripheral side of the first porous plate layer 1, and is also higher than the solid structure 8 disposed on the side of the bone graft window 9. The arrangement of this structure can ensure that the first rod-shaped structure 5 preferentially contacts the end plate and is thus embedded in the end plate.

[0099] In some preferred embodiments of the present invention, the second surface of the first porous plate layer 1 facing the second porous plate layer does not have a bone grafting window 9 .

[0100] In some preferred embodiments of the present invention, the second surface of the first porous plate layer 1 is a solid structure (i.e., it does not have a porous structure). This design allows the first porous plate layer 1 to be combined with the end plate separately, but the bone integration does not penetrate the upper and lower end plates, which ensures the fusion effect while retaining the elastic properties provided by the second porous plate layer 2, which is closer to a real intervertebral disc; it can reduce the motion compensation of the adjacent segments caused by fusion, reduce the impact on the adjacent segments, and avoid the degeneration of the adjacent segments after fusion.

[0101] In the present invention, the third porous plate layer 3 has a first surface facing away from the second porous plate layer 2 and a second surface facing the second porous plate layer 2 .

[0102] In some preferred embodiments of the present invention, the height of the third porous plate layer 3 is 0.5-2 mm, preferably 1-1.5 mm. The height direction of the third porous plate layer 3 is perpendicular to the first surface and the second surface of the third porous plate layer 3 .

[0103] In some preferred embodiments of the present invention, the porosity of the third porous plate layer 3 is 50%-95%, preferably 65%-80%. The porosity of the third porous plate layer 3 refers to the ratio of the pore volume of the third porous plate layer 3 to the volume of the third porous plate layer 3.

[0104] In some preferred embodiments of the present invention, the porosity of the third porous plate layer 3 is evenly distributed in the height direction of the third porous plate layer 3 .

[0105] In some preferred embodiments of the present invention, in the third porous plate layer 3, the pore size of the porous structure is 100-1000 μm, preferably 400-700 μm.

[0106] In some preferred embodiments of the present invention, the modulus of the third porous plate layer 3 is in the range of about 100 MPa-10 GPa, preferably 500 MPa-3 GPa.

[0107] In some preferred embodiments of the present invention, the third porous plate layer 3 has a height of 0.5-2 mm, a porosity of 50%-95%, a pore size of 100-1000 um, and a modulus range of about 100 MPa-10 GPa. Under these conditions, the third porous plate layer 3 can ensure good bone integration and mechanical properties.

[0108] In some preferred embodiments of the present invention, the third porous plate layer 3 has a height of 1-1.5 mm, a porosity of 65%-80%, a pore size of 400-700 μm, and a modulus of about 500 MPa-3 GPa.

[0109] In some preferred embodiments of the present invention, the first surface of the third porous plate layer 3 has a plurality of first rod-shaped structures 5 protruding in the height direction. The first rod-shaped structures 5 can be embedded in the end plate to achieve stable initial fixation.

[0110] In some preferred embodiments of the present invention, the second surface of the third porous plate layer 3 has a plurality of second rod-shaped structures 6 that are laterally connected to each other. The second rod-shaped structures 6 can improve the strength of the third porous plate layer 3; at the same time, the second rod-shaped structures 6 can be connected to the second porous plate layer 2, thereby improving the connection strength between the second rod-shaped structures 6 and the second porous plate layer 2; and the second rod-shaped structures 6 and the second porous plate layer 2 are pore-connected, allowing bone to grow through from top to bottom.

[0111] The lateral direction of the third porous plate layer 3 is a direction parallel to the first surface and the second surface of the third porous plate layer 3 .

[0112] In some preferred embodiments of the present invention, the outer peripheral side of the third porous plate layer 3 has a solid structure 7. By providing the solid structure 7 on the outer peripheral side of the third porous plate layer 3, the strength of the third porous plate layer 3 can be improved, and the stimulation of the fusion device to the soft tissue can also be avoided. The solid structure generally refers to a non-porous structure.

[0113] In the present invention, the shape and size of the bone graft window 9 are generally not required. Optionally, the area of ​​the bone graft window 9 accounts for 15-50% of the area of ​​the third porous plate layer 1 .

[0114] In some preferred embodiments of the present invention, the side wall surface of the bone graft window 9 has a solid structure 8. By providing the solid structure 8 on the side of the bone graft window 9, the strength of the third porous plate layer 3 can be improved, and the stimulation of the fusion device to the soft tissue can also be avoided.

[0115] In some preferred embodiments of the present invention, the first rod-shaped structure 5 disposed on the first surface of the third porous plate layer 3 is higher than the solid structure 7 disposed on the peripheral side of the third porous plate layer 3, and is also higher than the solid structure 8 disposed on the side of the bone graft window 9. The arrangement of this structure can ensure that the first rod-shaped structure 5 preferentially contacts the end plate and is thus embedded in the end plate.

[0116] In some preferred embodiments of the present invention, the second surface of the third porous plate layer 3 facing the second porous plate layer does not have a bone grafting window 9 .

[0117] In some preferred embodiments of the present invention, the first surface of the third porous plate layer 3 is a solid structure (i.e., it does not have a porous structure). This design allows the third porous plate layer 3 to be combined with the end plate separately, but the bone integration does not penetrate the upper and lower end plates, which ensures the fusion effect while retaining the elastic properties provided by the second porous plate layer 2, which is closer to a real intervertebral disc; it can reduce the motion compensation of the adjacent segments caused by fusion, reduce the impact on the adjacent segments, and avoid the degeneration of the adjacent segments after fusion.

[0118] In some preferred embodiments of the present invention, the side surface of the second porous plate layer 2 has no solid wall.

[0119] In some preferred embodiments of the present invention, the second porous plate layer 2 includes but is not limited to a Gyroid structure, a Schwarz Diamond structure, and a Schwarz Primitive structure; preferably, the second porous plate layer 2 is a sheet-like Gyroid structure. The sheet-like Gyroid structure has good elasticity and strength, and the large open surface on the side is more convenient for bone grafting.

[0120] In some preferred embodiments of the present invention, in the porous structure of the second porous plate layer 2, the length of a unit cell ("unit cell" refers to the smallest repeating unit formed by holes and rods) is 2-10 mm, preferably 3-8 mm.

[0121] In some preferred embodiments of the present invention, in the porous structure of the second porous plate layer 2, the unit cell width is 2-10 mm, preferably 3-8 mm.

[0122] In some preferred embodiments of the present invention, in the porous structure of the second porous plate layer 2, the unit cell height is 2-10 mm, preferably 3-8 mm.

[0123] In the porous structure of the second porous plate layer 2, in a rectangular coordinate system, height refers to a direction perpendicular to the first surface and the second surface of the second porous plate layer, and the length and width directions are perpendicular to the height direction.

[0124] In some preferred embodiments of the present invention, in the porous structure of the second porous plate layer 2, the length, width and height of the single cell range from 2 to 10 mm, preferably from 3 to 8 mm. The length, width and height range can ensure a sufficiently large surface area and sufficiently large surface pores to facilitate bone grafting and improve the combination with the bone.

[0125] In some preferred embodiments of the present invention, in the porous structure of the second porous plate layer 2, the wall thickness generally refers to the thickness imparted to the curved surface of 0.15-1.5 mm, preferably 0.2-1.0 mm.

[0126] In some preferred embodiments of the present invention, the modulus of the second porous plate layer 2 is in the range of 50 MPa-10 Gpa, preferably 300 MPa-3 Gpa.

[0127] In some preferred embodiments of the present invention, the porosity of the second porous plate layer 2 is 50%-95%, preferably 65%-85%.

[0128] In some preferred embodiments of the present invention, a mounting hole is provided on the side of the second porous plate layer 2 .

[0129] In some preferred embodiments of the present invention, the porosity of the first porous plate layer 1 and the third porous plate layer 3 is 50%-80%, and the modulus is 1-10 GPa; the porosity of the second porous plate layer 2 is 50%-80%, and the modulus is 1-10 GPa.

[0130] In some preferred embodiments of the present invention, the porosity of the first porous plate layer 1 and the third porous plate layer 3 is 70%-95%, and the modulus is 100MPa-3GPa, and the porosity of the second porous plate layer 2 is 70%-95%, and the modulus is 50MPa-3GPa.

[0131] In some preferred embodiments of the present invention, the porous fusion cage is a cervical fusion cage or a thoracolumbar fusion cage.

[0132] The cervical fusion cage may be a cervical fusion cage suitable for anterior approach surgery.

[0133] The thoracolumbar fusion cage may be a thoracolumbar fusion cage suitable for anterior approach surgery, lateral approach surgery or posterior approach surgery.

[0134] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0135] The reagents and raw materials used in the present invention are commercially available.

[0136] The positive and progressive effects of the present invention are:

[0137] (1) The upper and lower surfaces of the existing fusion device are three-periodic minimal surface porous structures. The upper and lower surfaces of the present invention are dense irregular porous structures with pore sizes and porosities suitable for bone integration and a larger end plate contact area, thereby improving bone integration efficiency, and a larger contact area can avoid sinking.

[0138] (2) The side surface of the existing fusion device is a solid wall. However, the side surface of the present invention is an open three-period minimal curved surface porous structure. The open side structure can be used for bone grafting and bone integration. The side solid wall increases the rigidity of the fusion device. The present invention has no solid wall, which can minimize the rigidity of the fusion device.

[0139] (3) The stiffness modulus of existing fusion devices is about 3-14GPa. The modulus of the fusion device of the present invention can be as low as 50-500MPa, and the lower modulus can match the bone modulus of osteoporotic patients. The low modulus is achieved by adjusting the modulus of the non-standard porous surface and the three-period minimal surface in the middle. The modulus of the fusion device is designed based on the patient's bone density. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] Figure 1 The figure is a schematic flow chart of the method for designing a porous fusion device according to the present invention.

[0141] Figure 2 It is a schematic diagram of the three-dimensional structure of the cervical fusion cage of the present invention.

[0142] Figure 3 It is a top view of the cervical fusion cage of the present invention.

[0143] Figure 4 for Figure 2 Schematic diagram of the cross section of the cervical fusion cage.

[0144] Figure 5 for Figure 2Schematic diagram of the three-dimensional structure of the cervical fusion cage.

[0145] Figure 6 for Figure 4 Schematic diagram of the structure of the first surface of the first porous plate layer (the surface facing away from the second porous plate layer).

[0146] Figure 7 for Figure 4 Schematic diagram of the structure of the second surface of the first porous plate layer (the surface facing the second porous plate layer).

[0147] Figure 8 It is a front view of another cervical fusion cage of the present invention.

[0148] Fig. 9 for Figure 8 Top view of the cervical fusion cage.

[0149] Fig.10 for Figure 8 Schematic diagram of the cross section of the cervical fusion cage.

[0150] Fig.11 Schematic diagram of the process of generating a human femoral shaft prosthesis.

[0151] Fig.12 Schematic diagram of the process of generating another human femoral shaft prosthesis.

[0152] Fig.13 It is a schematic diagram of a bone tissue implant model generating device of the present invention.

[0153] Fig.14 It is a schematic structural diagram of the porous fusion device design device of the present invention.

[0154] Fig.15 It is a structural schematic diagram of a finite element module of the present invention.

[0155] Fig.16 It is a structural schematic diagram of a bone tissue implant generating device of the present invention.

[0156] The above drawings include the following reference numerals:

[0157] 10. Cervical fusion device; 11. First surface; 12. Second surface; 1. First porous plate layer with bone grafting window; 2. Second porous plate layer; 3. Third porous plate layer with bone grafting window; 4. Mounting hole; 5. Protruding rod-like structure; 6. Laterally interconnected rod-like structures; 7. The outer wall of the third porous plate layer with a solid structure; 8. The side wall solid structure of the bone grafting window; 9. Bone grafting window; 1A. First porous plate layer without bone grafting window; 3A. Third porous plate layer without bone grafting window; 410. Acquisition module; 420. Segmentation module; 430. Determination module; 440. Generation module; 510. Model acquisition module; 520. Manufacturing module. DETAILED DESCRIPTION

[0158] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0159] Example 1

[0160] This embodiment provides a porous fusion device design device, such as Fig.14 As shown, it includes: a three-dimensional model acquisition module, a mechanical calculation module, a finite element module, a fusion device parameter generation module and a fusion device design module;

[0161] The three-dimensional model acquisition module is used to acquire a three-dimensional model of a target area of ​​a target object;

[0162] The mechanical calculation module is used to calculate muscle and ligament load data;

[0163] The finite element module is used to determine the finite element analysis results based on the 3D model, the cage model, and the muscle and ligament load data.

[0164] The fusion device parameter generation module is used to determine the design parameters of the porous fusion device according to the finite element analysis results;

[0165] The fusion device design module is used to design the corresponding porous structure model according to the porous fusion device design parameters, and fuse the three layers of porous to obtain the target porous fusion device structure.

[0166] In this embodiment, the three-dimensional model of the target area of ​​the target object includes a model of the intervertebral disc to be removed of the target object, at least two vertebral models above and below the intervertebral disc to be removed, and at least one intervertebral disc model above and below the intervertebral disc to be removed.

[0167] Among them, the intervertebral disc model includes the end plate, annulus fibrosus and nucleus pulposus models.

[0168] In this embodiment, the three-dimensional model of the target area of ​​the target object can generally be obtained through CT data of the target patient. The three-dimensional model of the intervertebral disc can generally be obtained through MR data of the target patient.

[0169] In this embodiment, the upper and lower end plates in the intervertebral disc model correspond to the upper and lower porous layers of the fusion cage model; the annulus fibrosus corresponds to the middle porous layer of the fusion cage model; the nucleus pulposus corresponds to the bone graft material in the bone graft window of the fusion cage model. The nucleus pulposus can be a bone graft material such as autologous bone, allogeneic bone or artificial bone.

[0170] In this embodiment, the mechanical calculation module includes a skeletal muscle multi-body dynamics module, and the skeletal muscle multi-body dynamics module is used to calculate muscle and ligament load data according to the three-dimensional model and BMI information of the target object.

[0171] In this embodiment, the finite element module includes a finite element establishment module, a finite element analysis module and a finite element optimization module. Fig.15 As shown;

[0172] The finite element establishment module is used to establish a finite element model according to the three-dimensional model, the fusion device model, and muscle and ligament load data; the fusion device model includes a first porous plate layer, a second porous plate layer, and a third porous plate layer that are stacked;

[0173] The finite element analysis module is used to perform finite element calculation according to the finite element model to determine the finite element analysis results; the finite element analysis results include obtaining the Young's modulus G1 corresponding to the first porous plate layer of the fusion device model, the Young's modulus G2 corresponding to the second porous plate layer, and the Young's modulus G3 corresponding to the third porous plate layer;

[0174] The finite element calculation includes respectively determining the initial values ​​of Young's modulus G1', G2' and G3' corresponding to the first porous plate layer, the second porous plate layer and the third porous plate layer of the fusion device model, substituting the initial values ​​of Young's modulus G1', G2' and G3' into the finite element model for iterative calculation to obtain the optimal combination of G1, G2 and G3 corresponding to the optimal biomechanical condition;

[0175] The finite element optimization module is used to optimize the finite element analysis results, including optimizing the combination of G1, G2 and G3, and selecting the best combination of G1, G2 and G3.

[0176] Wherein, G1' is determined according to the Young's modulus of the vertebral cortex of the intervertebral disc to be removed in the target area of ​​the target object; G3' is determined according to the Young's modulus of the vertebral cortex of the intervertebral disc to be removed in the target area of ​​the target object; G2' is determined according to the Young's modulus of the intervertebral disc to be removed in the target area of ​​the target object. G1, G2, and G3 are preferably adjusted within the range of ±30% of their respective initial values. The method for obtaining G1', G2', and G3' comprises the following steps:

[0177] K1: Calculate bone mineral density based on the HU value in the CT data of the target patient;

[0178] The calculation formula for bone mineral density is:

[0179]

[0180] K2: Calculate the vertebral modulus based on the bone mineral density value, which includes Young's modulus, Poisson's ratio and shear modulus;

[0181] The calculation formula of Young's modulus is:

[0182] E z =-34.7+3230×BMD QCT , (MPa); E x =E Y =0.333E z , (MPa);

[0183] Poisson's ratio: v XY =0.381; v YZ =v XZ =0.104;

[0184] Shear modulus:

[0185] In this embodiment, the porous fusion device design parameters include porosity and pore size. The porosity and pore size are determined by determining the porosity and pore size corresponding to the Young's modulus according to the Young's modulus of the fusion device model in the finite element analysis results (for example, the Young's modulus G1 of the first porous plate layer, the Young's modulus G2 of the second porous plate layer, and the Young's modulus G3 of the third porous plate layer).

[0186] In this embodiment, the porous structure model can be obtained according to the method for generating a porous structure model, or can be prepared according to a bone tissue implant model generating device.

[0187] In one embodiment, the bone tissue implant model generation method is described by taking the method applied to a terminal as an example, and includes the following steps:

[0188] Step S110, obtaining a native bone model of the site to be implanted.

[0189] The site to be implanted may be a part of the human body where bone tissue is defective and bionic bone needs to be implanted.

[0190] Among them, the native bone model can be a three-dimensional reconstruction model of the human bone tissue structure.

[0191] In a specific implementation, the native bone tissue structure data of the site to be implanted can be input into the terminal, and the terminal performs three-dimensional reconstruction of the native bone tissue based on the native bone tissue structure data to obtain a native bone model of the site to be implanted.

[0192] For example, when the implantation site is the left femoral shaft, CT (Computed Tomography) data of the same position of the healthy side or allogeneic femoral shaft can be collected, and the left femoral shaft and the internal bone structure of the left femoral shaft can be three-dimensionally reconstructed based on the CT data to obtain a three-dimensional reconstructed model. The three-dimensional reconstructed model can be used as the native bone model of the left femoral shaft.

[0193] Step S120, dividing the native bone model into native bone units.

[0194] The native bone unit may be a model unit of native bone having preset structural characteristics.

[0195] In a specific implementation, the native bone model of the implanted part can be segmented according to a preset structure to obtain a plurality of native bone units, wherein the preset structure can be, but is not limited to, a regular hexahedron, a parallelepiped, and an irregular hexahedron.

[0196] For example, the geometric structure of the native bone unit is set to be a regular hexahedron, and the three-dimensional reconstructed model of the native bone can be segmented to obtain a plurality of regular hexahedrons with an edge length of 0.5 mm as the native bone units.

[0197] Step S130, determining the bionic bone unit corresponding to the native bone unit; the bone tissue characteristics of the bionic bone unit match the bone tissue characteristics of the native bone unit.

[0198] The bionic bone unit may be a model unit of a bionic bone.

[0199] The bone tissue feature may include a first bone tissue feature and a second bone tissue feature; the first bone tissue feature may be porosity, and the second bone tissue feature may be a spatial elastic modulus.

[0200] In a specific implementation, the porosity and spatial elastic modulus of the native bone unit can be determined, and the porosity and spatial elastic modulus of the native bone unit can be used as the bone tissue characteristics of the native bone unit. The initial values ​​of the unit parameters of the bionic bone unit are pre-set, and there is a mapping relationship between the unit parameters and the bone tissue characteristics. The unit parameters of the bionic bone unit are adjusted so that the porosity and spatial elastic modulus of the bionic bone unit obtained after adjustment match the porosity and spatial elastic modulus of the native bone unit respectively. According to the adjusted unit parameters of the bionic bone unit, the bionic bone unit corresponding to the native bone unit can be determined.

[0201] For example, when the native bone unit is a regular hexahedron, for each native bone unit, the three components of the spatial elastic modulus E1, E2, E3 and the porosity P can be used as bone tissue features. For the bionic bone unit, the mapping relationship is set as

[0202] E1'=g1(·),

[0203] E2'=g2(·),

[0204] E3'=g3(·),

[0205] P' = g4(·).

[0206] Wherein, E1', E2', E3' are the target values ​​of the three components of the spatial elastic modulus of the bionic bone unit, P' is the target value of the porosity of the bionic bone unit, and · represents the unit parameter of the bionic bone unit, and the unit parameter can be at least one. The bone tissue characteristics of the bionic bone unit are made equal to the bone tissue characteristics of the native bone unit, that is, E1'=E1, E2'=E2, E3'=E3, P'=P, and the unit parameters are adjusted. When the above four equations g1, g2, g3, and g4 are established at the same time, it is determined that the bone tissue characteristics of the bionic bone unit match the bone tissue characteristics of the native bone unit, and the bionic bone unit can be generated according to the unit parameters at this time.

[0207] The bionic bone unit (unit cell structure) can be a body-centered cubic pore structure with the regular hexahedron of the native bone unit as the frame. The unit parameters can be at least one of the number of wire rods, wire diameter, body center position and unit cell size, wherein the wire diameter can be the thickness of the wire rod in the unit cell structure, all the wire rods inside the unit cell structure intersect at one point, which is the body center of the unit cell structure, the body center position can be the coordinate of the body center of the unit cell structure, and the unit cell size can be the edge length of the native bone unit corresponding to the unit cell structure. The corresponding bone tissue characteristics can be determined according to the unit parameters, and the bone tissue characteristics can include spatial elastic modulus and porosity.

[0208] The porosity can be adjusted by changing the wire diameter. The wire diameter can be reduced to make the wire rod of the unit cell structure thinner, the porosity can be increased, and the size of the spatial elastic modulus can be reduced. Similarly, the wire diameter can be increased to make the wire rod of the unit cell structure thicker, the porosity can be reduced, and the size of the spatial elastic modulus can be increased.

[0209] The porosity can be adjusted by changing the unit cell size. The unit cell size can be reduced to reduce the porosity of the unit cell structure and increase the size of the spatial elastic modulus. Similarly, the unit cell size can be increased to increase the porosity of the unit cell structure and decrease the size of the spatial elastic modulus.

[0210] The method of adjusting the spatial elastic modulus by changing the body center position of the unit cell structure is that the original body-centered cubic structure is a symmetrical structure, and the mechanical properties in the three symmetry plane directions are the same, and the components of the spatial elastic modulus in the three directions are the same. By moving the body center position, the length and direction of the wire rod inside the unit cell structure can be changed, so that the mechanical properties in the three directions change accordingly. Therefore, by adjusting the body center position, the components of the spatial elastic modulus in the three directions of the unit cell structure can be controlled, so that the components of the spatial elastic modulus in the three directions are anisotropic.

[0211] It should be noted that in order to ensure the processability of the bionic bone unit, the adjustable range of the wire diameter needs to be limited. In addition, since the thickness of the porous layer of the implant is generally 0.5mm to 2mm, and to ensure that the porous layer has a sufficient number of pore structures, the unit cell size should not be too large. In practical applications, the unit cell size range can be set to 0.5mm to 1.5mm, and the wire diameter range can be set to 150μm to 400μm.

[0212] Step S140, generating a bone tissue implant model of the site to be implanted according to the bionic bone unit.

[0213] In a specific implementation, after determining the corresponding bionic bone unit for each native bone unit in the native bone model, all the obtained bionic bone units can be combined to generate a bionic bone tissue structure of the site to be implanted. The defect shape of the site to be implanted is determined, and the generated bionic bone tissue structure is intercepted according to the defect shape to obtain a bone tissue implant model of the site to be implanted.

[0214] For example, after executing the processing of step S130 for each regular hexahedral native bone unit in the native bone model and obtaining the bionic bone unit cell structure corresponding to each native bone unit, all unit cell structures can be combined to form a bone tissue structure having the same spatial elastic modulus distribution and the same porosity distribution as the native bone, as the bionic bone tissue structure of the part to be implanted. The bionic bone tissue structure is intercepted according to the defect shape of the part to be implanted to obtain a bone tissue implant model, and the bone tissue implant model can be used to manufacture a bone tissue implant.

[0215] The above-mentioned bone tissue implant model generation method first obtains the native bone model of the part to be implanted, then divides the native bone model into native bone units, then determines the bionic bone units corresponding to the native bone units, and finally generates the bone tissue implant model of the part to be implanted according to the bionic bone units; because the bone tissue characteristics of the bionic bone units match the bone tissue characteristics of the native bone units, the generated bionic bone tissue structure of the part to be implanted also matches the native bone tissue structure of the part to be implanted, and the generated bionic bone tissue structure is intercepted according to the defect shape of the part to be implanted, so as to obtain a bone tissue implant model that is well adapted to the native bone tissue structure of the part to be implanted, and a prosthesis is manufactured according to the bone tissue implant model to avoid prosthesis loosening.

[0216] In one embodiment, the above step S130 may specifically include:

[0217] Step S131, adjusting the unit parameters of the bionic bone unit according to the preset mapping relationship between the unit parameters of the bionic bone unit and the bone tissue characteristics, so that the bone tissue characteristics of the adjusted bionic bone unit match the bone tissue characteristics of the native bone unit;

[0218] Step S132, determining the bionic bone unit according to the adjusted unit parameters of the bionic bone unit.

[0219] In a specific implementation, a mapping relationship between unit parameters and bone tissue characteristics can be pre-set for the bionic bone unit, and the mapping relationship can be a function with unit parameters as independent variables and bone tissue characteristics as dependent variables. The bone tissue characteristics of the native bone unit are used as the target value of the bone tissue characteristics of the bionic bone unit, and the unit parameters in the function are adjusted, and the bone tissue characteristics change accordingly. When the bone tissue characteristics are consistent with the target value, the unit parameters at this time can be determined as the target unit parameters, and the bionic bone unit is generated according to the target unit parameters.

[0220] For example, the mapping relationship between the unit parameters of the bionic bone unit and the bone tissue characteristics can be set as

[0221] E1'=g1(·),

[0222] E2'=g2(·),

[0223] E3'=g3(·),

[0224] P' = g4(·).

[0225] Among them, E1', E2', E3' are the target values ​​of the spatial elastic modulus of the bionic bone unit, which are equal to the spatial elastic modulus of the native bone unit, P' is the target value of the porosity of the bionic bone unit, which is equal to the porosity of the native bone unit, and · represents the unit parameter of the bionic bone unit. The unit parameters are adjusted so that the spatial elastic modulus calculated according to the functions g1(·), g2(·), and g3(·) are equal to E1', E2', and E3', respectively, and the porosity calculated according to the function g4(·) is equal to P'. At this time, the adjusted unit parameters of the bionic bone unit can be used as the target unit parameters, and the body-centered cubic structure corresponding to the target unit parameters is determined as the bionic bone unit.

[0226] In this embodiment, the unit parameters of the bionic bone unit are adjusted according to the preset mapping relationship between the unit parameters of the bionic bone unit and the bone tissue characteristics, so that the bone tissue characteristics of the adjusted bionic bone unit match the bone tissue characteristics of the native bone unit, and then the bionic bone unit is determined according to the unit parameters of the adjusted bionic bone unit; the complexity of the bionic bone unit determination process can be reduced and the convenience of bone tissue implant model generation can be increased.

[0227] In one embodiment, the bone tissue characteristics of the bionic bone unit include a first bone tissue characteristic and a second bone tissue characteristic, and the unit parameters of the bionic bone unit include a first unit parameter and a second unit parameter. The above step S131 may specifically include: adjusting the first unit parameter and the second unit parameter of the bionic bone unit according to the mapping relationship, so that the adjusted first bone tissue characteristic and the second bone tissue characteristic of the bionic bone unit match the first bone tissue characteristic and the second bone tissue characteristic of the native bone unit respectively.

[0228] The first bone tissue characteristic may be porosity, and the second bone tissue characteristic may be spatial elastic modulus.

[0229] The first unit parameter may be the number of screw rods in the bionic bone unit and / or the wire diameter of the screw rods in the bionic bone unit, and the second unit parameter may be the body center position of the bionic bone unit.

[0230] In a specific implementation, a mapping relationship between the first unit parameter, the second unit parameter and the first bone tissue feature, the second bone tissue feature can be pre-set for the bionic bone unit, and the mapping relationship can be a function with the first unit parameter and the second unit parameter as independent variables and the first bone tissue feature and the second bone tissue feature as dependent variables. The first bone tissue feature and the second bone tissue feature of the native bone unit are respectively used as the target values ​​of the first bone tissue feature and the second bone tissue feature of the bionic bone unit, and the first unit parameter and the second unit parameter in the function are adjusted, and the first bone tissue feature and the second bone tissue feature change accordingly. When the bone tissue feature is consistent with the target value, the first unit parameter and the second unit parameter at this time can be determined as the target unit parameter, and the bionic bone unit is determined according to the target unit parameter.

[0231] For example, the bionic bone unit can be set to be a regular hexahedron with an edge length of 0.5 mm, and the mapping relationship between the unit parameters and the bone tissue characteristics is:

[0232] E1'=g1(d,x',y',z'),

[0233] E2'=g2(d,x',y',z'),

[0234] E3'=g3(d,x',y',z'),

[0235] P'=g4(d,x',y',z').

[0236] Among them, d and (x', y', z') are the wire diameter and body center position of the bionic bone unit, respectively; E1', E2', and E3' are the target values ​​of the spatial elastic modulus of the bionic bone unit, which are equal to the spatial elastic modulus of the native bone unit; and P' is the target value of the porosity of the bionic bone unit, which is equal to the porosity of the native bone unit. (d, x', y', z') is adjusted so that the spatial elastic modulus calculated by the functions g1(d, x', y', z'), g2(d, x', y', z'), and g3(d, x', y', z') are equal to E1', E2', and E3', respectively, and the porosity calculated by the function g4(d, x', y', z') is equal to P'. At this time, the unit parameters (d, x', y', z') of the bionic bone unit after adjustment can be used as the target unit parameters, and the body-centered cubic structure determined according to the target unit parameters is used as the bionic bone unit.

[0237] In one embodiment, the unit parameters of the bionic bone unit also include a third unit parameter; the above-mentioned step S131 may further specifically include: adjusting the first unit parameter, the second unit parameter and the third unit parameter of the bionic bone unit according to the mapping relationship, so that the first bone tissue feature and the second bone tissue feature of the adjusted bionic bone unit match the first bone tissue feature and the second bone tissue feature of the native bone unit respectively.

[0238] The third unit parameter may be the unit cell size of the bionic bone unit.

[0239] In a specific implementation, the mapping relationship between the first unit parameter, the second unit parameter, the third unit parameter and the first bone tissue feature and the second bone tissue feature can be pre-set for the bionic bone unit, and the mapping relationship can be a function with the first unit parameter, the second unit parameter, and the third unit parameter as independent variables and the first bone tissue feature and the second bone tissue feature as dependent variables. The first bone tissue feature and the second bone tissue feature of the native bone unit are respectively used as the target values ​​of the first bone tissue feature and the second bone tissue feature of the bionic bone unit, and the first unit parameter, the second unit parameter, and the third unit parameter in the function are adjusted, and the first bone tissue feature and the second bone tissue feature change accordingly. When the bone tissue feature is consistent with the target value, the first unit parameter, the second unit parameter, and the third unit parameter at this time can be determined as the target unit parameter, and the bionic bone unit is determined according to the target unit parameter.

[0240] For example, the mapping relationship between the unit parameters of the bionic bone unit and the bone tissue characteristics can be set as

[0241] E1'=g1(d,D,x',y',z'),

[0242] E2'=g2(d,D,x',y',z'),

[0243] E3'=g3(d,D,x',y',z'),

[0244] P'=g4(d,D,x',y',z').

[0245] Wherein, d, D, (x', y', z') are the wire diameter, unit cell size and body center position of the bionic bone unit, respectively; E1', E2', E3' are the target values ​​of the spatial elastic modulus of the bionic bone unit, which are equal to the spatial elastic modulus of the native bone unit; P' is the target value of the porosity of the bionic bone unit, which is equal to the porosity of the native bone unit. Adjust (d, D, x', y', z') so that the spatial elastic modulus calculated according to the functions g1(d, D, x', y', z'), g2(d, D, x', y', z'), and g3(d, D, x', y', z') are equal to E1', E2', and E3', respectively, and the porosity calculated according to the function g4(d, D, x', y', z') is equal to P'. At this time, the unit parameters (d, D, x', y', z') of the adjusted bionic bone unit can be used as target unit parameters, and the body-centered cubic structure corresponding to the target unit parameters is determined as the bionic bone unit.

[0246] Fig.11Another schematic diagram of the process of generating a human femoral stem prosthesis is provided. Fig.11 , the spatial elastic modulus distribution E1(x,y,z), E2(x,y,z), E3(x,y,z) and porosity distribution P(x,y,z) of the femoral shaft can be obtained. The directions of E1, E2, and E3 are mutually perpendicular, (x,y,z) is the coordinate of the center position of a certain space, which represents the cubic space centered on (x,y,z), and the directions of E1, E2, and E3 and the size of the cubic space can be determined as needed. Here, the direction of E1 is defined as the femoral midline direction, the cubic space is 0.5mm in side length, E1(x,y,z) is the spatial elastic modulus of the bone in the femoral midline direction in the cubic space with a range of 0.5mm in side length at the position (x,y,z), and P(x,y,z) is the average porosity of the bone in the femoral midline in the cubic space with a range of 1mm in side length at the position (x,y,z). According to the relationship between the node position (x', y', z') of the porous unit cell, the wire diameter d, the unit cell size D and the unit cell elastic modulus E1', E2', E3' and the unit cell porosity P', the modulus distribution and porosity distribution of the bone are fitted:

[0247] E1(x,y,z)=E1'(x,y,z)=g1(d,D,x',y',z'),

[0248] E2(x,y,z)=E2'(x,y,z)=g2(d,D,x',y',z'),

[0249] E3(x,y,z)=E3'(x,y,z)=g3(d,D,x',y',z'),

[0250] P(x,y,z)=P'(x,y,z)=g4(d,D,x',y',z').

[0251] A bionic bone porous structure model can be established according to the wire diameter d, unit cell size D and unit cell center point position (x', y', z') corresponding to different spatial positions (x, y, z), and then the required porous structure area can be cut out according to the implant shape design.

[0252] In this embodiment, by adjusting the first unit parameter, the second unit parameter and the third unit parameter of the bionic bone unit according to the mapping relationship, the first bone tissue feature and the second bone tissue feature of the adjusted bionic bone unit are matched with the first bone tissue feature and the second bone tissue feature of the native bone unit respectively; the complexity of the bionic bone unit determination process can be reduced and the convenience of bone tissue implant model generation can be increased.

[0253] Fig.12 Another schematic diagram of the process of generating a human femoral stem prosthesis is provided. Fig.12In the case of left femoral shaft defect, bone CT data of the same position of the healthy side or allogeneic femoral shaft can be obtained. Fig.11 The CT data of the healthy side femoral shaft was taken, and the femoral shaft and internal bone structure were reconstructed in three dimensions through the CT data. The reconstructed bone model was segmented into several regular hexahedrons with an edge length of 0.5 mm, and the spatial elastic modulus of each small regular hexahedron was calculated through finite element mechanical simulation analysis. Fig.12 The moduli in three directions perpendicular to the outer surface of the regular hexahedron are used to represent the spatial elastic modulus, which are E1, E2, and E3, respectively, and then the porosity P of the bone model inside the regular hexahedron is measured. The regular hexahedron space is identified by the body-centered coordinates (x1, y1, z1) of a regular hexahedron, and the regular hexahedron has four attributes, namely, E1(x, y, z), E2(x, y, z), E3(x, y, z) and P(x, y, z). By determining the attributes of each regular hexahedron, the spatial elastic modulus distribution and porosity distribution of the bone in the femoral shaft defect site can be obtained, namely, E1(x, y, z), E2(x, y, z), E3(x, y, z) and P(x, y, z).

[0254] Then, a body-centered cubic porous unit cell structure is generated with a certain segmented regular hexahedron as the framework. The wire diameter of the porous structure is d, and the node position of the internal wire rod is (x', y', z'). The spatial modulus E and porosity P of the unit cell structure have a mapping relationship with the wire diameter d and the node position, which are defined as E1'(x', y', z', d), E2'(x', y', z', d), E3'(x', y', z', d) and P'(x', y', z', d). The wire diameter d and the node position (x', y', z') are adjusted so that the following equations are simultaneously true:

[0255] E1'(x',y',z',d)=E1(x,y,z),

[0256] E2'(x', y', z', d)=E2(x, y, z),

[0257] E3'(x',y',z',d)=E3(x,y,z),

[0258] P'(x',y',z',d)=P(x,y,z).

[0259] Finally, each regular hexahedron is treated in the same way and all the porous unit cell structures are combined together to form a porous structure with the same modulus distribution characteristics and porosity distribution characteristics as the native bone. The porous structure of the corresponding shape is cut according to actual needs and implanted into the bone defect site.

[0260] It should be noted that in each unit cell structure, the wire diameter of each wire rod is variable, so as to achieve directional adjustment of the modulus; the wire diameter of the outer frame of the unit cell structure can also be kept unchanged, and only the wire diameter of the wire rod inside the unit cell can be adjusted; the unit cell structure can also be a variation based on other regular unit cells, for example, it can be a variation of the diamond structure, that is, the wire diameter of the wire rod inside the unit cell structure is variable, not necessarily the body diagonal; the porosity and mechanical properties of the aperture can also be adjusted by adding or removing wire rods, that is, the number of wire rods can be variable.

[0261] The present application designs a porous structure, the elastic modulus distribution of which is the same as the elastic modulus of the bone on the contact surface with the human bone, thereby increasing the compatibility of the porous structure with the human bone tissue, promoting bone ingrowth to the maximum extent, improving the short-term and long-term stability of the prosthesis, and avoiding prosthesis loosening.

[0262] Based on the same inventive concept, the embodiment of the present application also provides a bone tissue implant and a generation device thereof for realizing the above-mentioned method for generating a bone tissue implant and a model thereof. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above-mentioned method, so the specific limitations in the embodiments of one or more bone tissue implant and a generation device thereof provided below can refer to the limitations of the method for generating a bone tissue implant and a model thereof in the above text, and will not be repeated here.

[0263] In one embodiment, Fig.13 As shown, a bone tissue implant model generation device is provided, comprising: an acquisition module 410, a segmentation module 420, a determination module 430 and a generation module 440, wherein:

[0264] An acquisition module 410 is used to acquire a native bone model of a site to be implanted;

[0265] The segmentation module 420 is used to segment the native bone model into native bone units;

[0266] A determination module 430 is used to determine the bionic bone unit corresponding to the native bone unit; the bone tissue characteristics of the bionic bone unit match the bone tissue characteristics of the native bone unit;

[0267] The generation module 440 is used to generate a bone tissue implant model of the to-be-implanted site based on the bionic bone unit.

[0268] In one embodiment, the determination module 430 includes:

[0269] A parameter adjustment module, used to adjust the unit parameters of the bionic bone unit according to a preset mapping relationship between the unit parameters of the bionic bone unit and the bone tissue characteristics, so that the bone tissue characteristics of the adjusted bionic bone unit match the bone tissue characteristics of the native bone unit;

[0270] The bone unit determination module is used to determine the bionic bone unit according to the adjusted unit parameters of the bionic bone unit.

[0271] In one embodiment, the parameter adjustment module is further used to adjust the first unit parameter and the second unit parameter of the bionic bone unit according to the mapping relationship, so that the first bone tissue feature and the second bone tissue feature of the adjusted bionic bone unit match the first bone tissue feature and the second bone tissue feature of the native bone unit respectively.

[0272] In one embodiment, the parameter adjustment module is also used to adjust the first unit parameter, the second unit parameter and the third unit parameter of the bionic bone unit according to the mapping relationship, so that the first bone tissue feature and the second bone tissue feature of the adjusted bionic bone unit match the first bone tissue feature and the second bone tissue feature of the native bone unit respectively.

[0273] In one embodiment, the first bone tissue characteristic includes porosity, and the second bone tissue characteristic includes spatial elastic modulus; the first unit parameter includes the number of wire rods in the bionic bone unit and / or the wire diameter of the wire rods in the bionic bone unit, the second unit parameter includes the body center position of the bionic bone unit, and the third unit parameter includes the unit cell size of the bionic bone unit.

[0274] In one embodiment, the bionic bone unit comprises at least three screw rods, and the wire diameters of the screw rods in the bionic bone unit are not all equal.

[0275] In one embodiment, the second bone tissue feature at least includes a first feature component, a second feature component and a third feature component, and the first feature component, the second feature component and the third feature component are perpendicular to each other.

[0276] In one embodiment, the generation module 440 is further used to generate a bionic bone tissue structure of the site to be implanted based on the bionic bone unit; and to intercept the bionic bone tissue structure according to the defect shape of the site to be implanted to obtain a bone tissue implant model of the site to be implanted.

[0277] In one embodiment, Fig.16 As shown, a bone tissue implant generation device is provided, comprising: a model acquisition module 510 and a manufacturing module 520, wherein:

[0278] A model acquisition module 510 is used to obtain a bone tissue implant model of a part to be implanted according to the steps in the above-mentioned bone tissue implant model generation method embodiments;

[0279] The manufacturing module 520 is used to manufacture according to the bone tissue implant model to obtain the bone tissue implant for the site to be implanted.

[0280] Each module in the above-mentioned bone tissue implant and model generation device can be implemented in whole or in part by software, hardware and their combination. Each module can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to each module above.

[0281] This embodiment also provides a design method for a porous fusion device. Figure 1 As shown, it includes the following steps:

[0282] Acquire a three-dimensional model of a target area of ​​a target object;

[0283] obtaining muscle and ligament loading data of a target area of ​​a target subject;

[0284] Determine finite element analysis results based on the 3D model, cage model, and muscle and ligament load data;

[0285] The design parameters of the porous fusion device were determined based on the finite element analysis results.

[0286] This embodiment also provides a porous fusion device, which is designed by using a porous fusion device design device such as the porous fusion device design device of the above embodiment 1, or is obtained by executing a porous fusion device design method such as the above embodiment 1.

[0287] This embodiment further provides a storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the design method of the above-mentioned embodiment 1.

[0288] This embodiment also provides an electronic device, which includes one or more processors and a memory, wherein the memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors execute the steps of the design method of the above-mentioned embodiment 1.

[0289] Example 2

[0290] like Figure 2 , Figure 3 , Figure 4As shown, in this embodiment, the cervical fusion cage 10 includes: a first porous plate layer 1, a second porous plate layer 2 and a third porous plate layer 3 which are stacked. The third porous plate layer 3 is arranged between the first porous plate layer 1 and the second porous plate layer 2, and the second porous plate layer 2 includes a first surface 11 and a second surface 12 which are arranged opposite to each other, the first surface 11 is connected to the first porous plate layer 1, and the second surface 12 is connected to the third porous plate layer 3.

[0291] The first porous plate layer 1 and the third porous plate layer 3 are provided with a dense non-standard porous structure with a height of 0.5-2mm, a porosity of 50%-95%, a pore size of 100-1000μm, and a modulus range of about 100MPa-10GPa. It can ensure good bone integration performance and mechanical properties. A bone grafting window 9 is provided between the first porous plate layer 1 and the third porous plate layer 3. The area of ​​the bone grafting window 9 accounts for 15-50% of the area of ​​the first porous plate layer 1 and the third porous plate layer 3, respectively, and its inner and outer peripheral sides have solid structures 7 and 8. The solid structures 7 and 8 can further enhance the strength of 1 and 3 while avoiding the stimulation of the fusion device to the soft tissue.

[0292] The second porous plate layer 2 is a lamellar three-period minimal surface structure, including but not limited to a Gyroid structure, a Schwarz Diamond structure, and a Schwarz Primitive structure. Preferably, the present embodiment adopts a lamellar Gyroid structure, which has good elastic properties and strength, and a large open surface on the side is more convenient for bone grafting. The unit cell length, width, and height of the second porous plate layer 2 range from 2 to 10 mm to ensure a sufficiently large surface area and sufficiently large surface pores to facilitate bone grafting and improve the combination with the bone. The wall thickness of the second porous plate layer 2 is 0.15-1.5 mm, the modulus range is 50 MPa-10 GPa, and the porosity is 50%-95%. The second porous plate layer 2 also includes a mounting hole 4.

[0293] like Figure 5 As shown, the pores between the first porous plate layer 1, the third porous plate layer 3 and the second porous plate layer 2 are connected, allowing bones to grow through from top to bottom.

[0294] like Figure 6 As shown, the outward surfaces of the first porous plate layer 1 and the third porous plate layer 3 (the surfaces facing away from the second porous plate layer) have protruding first rod-shaped structures 5, which can be embedded in the end plate to achieve stable initial fixation. The protruding first rod-shaped structures 5 on the outer surfaces of the first porous plate layer 1 and the third porous plate layer 3 protrude (that is, are higher than) the solid structures 7 and 8 to ensure that 5 preferentially contacts the end plate and is thus embedded in the end plate.

[0295] like Figure 7As shown, the first porous plate layer 1 and the third porous plate layer 3 have the second rod-shaped structures 6 which are connected to each other transversely, and 6 improves the strength of 1 and 3. At the same time, 6 is connected to 2, which improves the connection strength between 1, 3 and 2.

[0296] The upper and lower surfaces of the fusion device in this embodiment are dense irregular porous structures with pore sizes and porosities suitable for bone integration and a larger end plate contact area, thereby improving bone integration efficiency, and a larger contact area can avoid sinking.

[0297] In addition, the side surface of the fusion device in this embodiment is an open three-period minimal curved surface porous structure. The side open structure can be used for bone grafting and bone integration. The side solid wall increases the rigidity of the fusion device. The fusion device in this embodiment has no solid wall, which can minimize the rigidity of the fusion device.

[0298] The modulus of the fusion device of this embodiment can be as low as 50-500 MPa, and a lower modulus can match the bone modulus of osteoporotic patients. The low modulus is achieved by adjusting the modulus of the non-standard porous surface and the three-period minimal surface in the middle.

[0299] Example 3

[0300] like Figure 8 , Fig. 9 , Fig.10 As shown, on the basis of Example 2, the cervical fusion device in this embodiment has no intermediate bone grafting window in the first porous plate layer 1A and the third porous plate layer 3A. The inward surfaces of the first porous plate layer 1A and the third porous plate layer 3A are sealed with a solid layer, and the second porous plate layer 2 is connected to the solid layer. This design allows the first porous plate layer 1A and the third porous plate layer 3A of the fusion device to be combined with the end plates separately, but the bone integration does not penetrate the upper and lower end plates, which ensures the fusion effect while retaining the elastic properties provided by the intermediate layer 2, which is closer to a real intervertebral disc. It can reduce the motion compensation of the adjacent segments caused by fusion, reduce the impact on the adjacent segments, and avoid the degeneration of the adjacent segments after fusion.

[0301] It should be noted that if Figure 4 , Fig.10 As shown, Figure 4 , Fig.10 The up-down direction in the figure is the thickness direction of the cervical fusion cage body, and the thickness direction is consistent with the stacking direction.

[0302] The porosity of the first porous plate layer 1 refers to the ratio of the pore volume of the first porous plate layer 1 to the volume of the first porous plate layer 1; the porosity of the second porous plate layer 2 refers to the ratio of the pore volume of the second porous plate layer 2 to the volume of the second porous plate layer 2; the porosity of the third porous plate layer 3 refers to the ratio of the pore volume of the third porous plate layer 3 to the volume of the third porous plate layer 3.

[0303] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0304] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0305] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

Claims

1. A porous fusion device design device, characterized in that: It includes: a three-dimensional model acquisition module, a mechanical calculation module, a finite element module and a fusion device parameter generation module; The three-dimensional model acquisition module is used to acquire a three-dimensional model of a target area of ​​a target object; The mechanical calculation module is used to calculate muscle and ligament load data of a target area of ​​a target object; The finite element module is used to determine the finite element analysis result according to the three-dimensional model, the fusion cage model and the muscle and ligament load data; The fusion device parameter generation module is used to determine the porous fusion device design parameters according to the finite element analysis results.

2. The porous fusion device design device according to claim 1, characterized in that: The three-dimensional model of the target area of ​​the target object includes a model of the intervertebral disc to be removed of the target object, at least two vertebral models above and below the intervertebral disc to be removed of the target object, and at least one intervertebral disc model above and below the intervertebral disc to be removed of the target object.

3. The porous fusion device design device according to claim 2, characterized in that: The intervertebral disc model includes an end plate, an annulus fibrosus and a nucleus pulposus model.

4. The porous fusion device design device according to claim 1, characterized in that: The mechanical calculation module includes a skeletal muscle multi-body dynamics module, and the skeletal muscle multi-body dynamics module is used to calculate muscle and ligament load data according to the three-dimensional model and BMI information of the target object.

5. The porous fusion device design device according to claim 1, characterized in that: The finite element module includes a finite element establishment module and a finite element analysis module; The finite element establishment module is used to establish a finite element model according to the three-dimensional model, the fusion cage model and the muscle and ligament load data; the finite element analysis module is used to perform finite element calculation according to the finite element model to determine the finite element analysis result; The finite element analysis result includes obtaining the Young's modulus of the fusion device model.

6. The porous fusion device design device according to claim 5, characterized in that: The fusion device model includes a first porous plate layer, a second porous plate layer and a third porous plate layer which are stacked; the Young's modulus of the fusion device model includes: Young's modulus G1 corresponding to the first porous plate layer, Young's modulus G2 corresponding to the second porous plate layer and Young's modulus G3 corresponding to the third porous plate layer.

7. The porous fusion device design device according to claim 6, characterized in that: The finite element calculation includes respectively determining initial values ​​G1', G2' and G3' of Young's modulus corresponding to the first porous plate layer, the second porous plate layer and the third porous plate layer of the fusion device model, substituting the initial values ​​G1', G2' and G3' of Young's modulus into the finite element model for iterative calculation to obtain the optimal combination of G1, G2 and G3 corresponding to the optimal biomechanical condition; Wherein, the G1' is determined according to the Young's modulus of the vertebral cortex above the intervertebral disc to be removed in the target area of ​​the target object; the G3' is determined according to the Young's modulus of the vertebral cortex below the intervertebral disc to be removed in the target area of ​​the target object; and the G2' is determined according to the Young's modulus of the intervertebral disc to be removed in the target area of ​​the target object.

8. The porous fusion device design device according to claim 6 or 7, characterized in that: The finite element module also includes a finite element optimization module; The finite element optimization module is used to optimize the finite element analysis results, including optimizing the combination of G1, G2 and G3, and screening out the best combination of G1, G2 and G3.

9. The porous fusion device design device according to claim 5, characterized in that: The method of determining the design parameters of the porous fusion device includes determining the porosity and pore size corresponding to the Young's modulus of the fusion device model in the finite element analysis result.

10. The porous fusion cage design device according to any one of claims 1 to 9, characterized in that: It also includes a fusion device design module, which is used to design a corresponding porous structure model according to the porous fusion device design parameters to obtain a target porous fusion device.

11. A method for designing a porous fusion device, characterized in that: It includes the following steps: Acquire a three-dimensional model of a target area of ​​a target object; Acquiring muscle and ligament load data of a target area of ​​the target object; Determining finite element analysis results based on the three-dimensional model, the fusion cage model, and the muscle and ligament load data; The design parameters of the porous fusion device are determined according to the finite element analysis results.

12. A porous fusion device, characterized in that: The porous fusion device is designed by using the porous fusion device design device according to any one of claims 1 to 10, or is obtained by executing the porous fusion device design method according to claim 11.

13. A porous fusion device, characterized in that: It comprises a first porous plate layer, a second porous plate layer and a third porous plate layer which are stacked; (1) the second porous plate layer is disposed between the first porous plate layer and the third porous plate layer; The second porous plate layer has a lamellar three-periodic minimal surface porous structure; The first porous plate layer and the third porous plate layer have a dense irregular porous structure; (2) The first porous plate layer and the third porous plate layer are provided with through bone grafting windows, and the pores among the first porous plate layer, the second porous plate layer and the third porous plate layer are connected; Alternatively, the first porous plate layer and the third porous plate layer do not have bone grafting windows, and the pores among the first porous plate layer, the second porous plate layer and the third porous plate layer are not connected.

14. The porous fusion device according to claim 13, characterized in that: The first porous plate layer and the third porous plate layer each have a first surface facing away from the second porous plate layer and a second surface facing the second porous plate layer; the first surface has a protruding first rod-shaped structure; and the second surface has a second rod-shaped structure laterally connected to each other.

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