Cervical interbody fusion cage

Abstract

The invention provides a cervical interbody fusion cage, a plurality of bone ingrowth directions are arranged on the cervical interbody fusion cage, the cervical interbody fusion cage comprises an inner supporting frame and an outer supporting frame arranged on the outer side of the inner supporting frame in a sleeving mode, and a buffer area is reserved between the inner supporting frame and the outer supporting frame. The buffer region is filled with a lattice structure; a cylindrical groove is formed in the side wall of the inner supporting frame, a stress stimulation piece is movably arranged in the cylindrical groove, and the cylindrical groove is provided with an impact inner wall corresponding to the stress stimulation piece. According to the cervical interbody fusion cage, the stress stimulation piece filled in the cylindrical groove can serve as a stress stimulation source, inertia force applied in the movement process of a human body is utilized for movement, and after the cervical interbody fusion cage is implanted, the stress stimulation piece can release mechanical waves in the mode of impacting the inner wall of the cylindrical groove; stress stimulation generated by mechanical waves promotes the osseointegration process, and postoperative rehabilitation of the patient is accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of intervertebral fusion, and in particular to a cervical intervertebral fusion device. Background Art

[0002] Intervertebral fusion surgery is a surgical method used to treat spinal diseases. Its main purpose is to relieve symptoms such as pain and nerve compression caused by disc degeneration, herniation, vertebral slippage, etc., and restore the stability and normal physiological curvature of the spine. During the operation, an intervertebral fusion device is implanted between adjacent vertebrae to replace the damaged or degenerated intervertebral disc, help stabilize the spine and promote fusion between vertebrae. Titanium alloys are widely used in the implant field due to their excellent biocompatibility.

[0003] However, since the elastic modulus of titanium alloy is significantly higher than that of human bone, direct implantation of titanium alloy entities may induce a stress shielding effect, leading to osteolysis. In addition, traditional solid titanium alloy structures lack sufficient space for bone ingrowth, which limits the efficiency of bone integration and comprehensive and rapid bone ingrowth.

[0004] Therefore, in order to solve the above problems, the present invention proposes an intervertebral fusion cage which has a stable structure and can promote bone growth. Summary of the invention

[0005] In order to solve the above problems existing in the existing cervical intervertebral fusion cage, the present invention provides a cervical intervertebral fusion cage.

[0006] According to one object of the present invention, the present invention provides a cervical intervertebral fusion device, wherein a plurality of bone ingrowth directions are arranged on the cervical intervertebral fusion device, the cervical intervertebral fusion device comprises an inner support frame and an outer support frame sleeved on the outer side of the inner support frame, a buffer area is reserved between the inner support frame and the outer support frame, and the buffer area is filled with a lattice structure;

[0007] A cylindrical groove is arranged on the side wall of the inner support frame, a stress stimulation piece is movably arranged in the cylindrical groove, the cylindrical groove is provided with an impact inner wall corresponding to the stress stimulation piece, and the stress stimulation piece is arranged to move along with the cervical intervertebral fusion cage in at least one of the bone ingrowth directions.

[0008] Preferably, both the inner supporting frame and the outer supporting frame are provided with openings, the openings are arranged along the bone ingrowth direction, and the lattice structure is filled in the openings.

[0009] Preferably, the outer support frame and the inner support frame are provided with a plurality of faces in the circumferential direction, each face is provided with the opening, and the opening is a polygonal opening, wherein the corners of the opening are rounded.

[0010] Preferably, the lattice structure is a body-centered cubic lattice structure, and the overall porosity of the cervical intervertebral fusion cage is about 70%.

[0011] Preferably, the inner side of the inner support frame forms a bone graft window, and the bone graft window is configured to be filled with autologous bone or allogeneic bone, and the axial and radial directions of the bone graft window correspond to different bone ingrowth directions, respectively.

[0012] Preferably, the cylindrical groove is arranged at the center position of each surface of the inner support frame in the circumferential direction, the cylindrical groove is closed at both ends in the axial direction, and an opening suitable for the stress stimulation component to enter is opened on the side of the cylindrical groove facing the bone graft window.

[0013] Preferably, the cylindrical groove is arranged along the direction of the bone grafting window, the opening on the cylindrical groove and the two ends of the cylindrical groove in the axial direction are arranged at intervals, and the size of the opening is slightly larger than the size of the stress stimulation component.

[0014] Preferably, the dimension of the stress stimulation member in the radial direction of the cylindrical groove is slightly smaller than the radial dimension of the cylindrical groove.

[0015] Preferably, the cervical intervertebral fusion cage is configured to be used in conjunction with a titanium plate.

[0016] Preferably, the cervical intervertebral fusion device is made of titanium alloy material as a whole, the cylindrical groove is a cylindrical cylindrical groove, and the stress stimulation piece is a spherical stress stimulation piece;

[0017] In the radial direction of the bone grafting window, the size of the cylindrical groove is larger than the size of the side wall of the inner support frame, wherein the two sides of the cylindrical groove extend toward the inner side and the outer side of the inner support frame respectively, and in the axial direction of the bone grafting window, the two ends of the cylindrical groove are respectively flush with the two ends of the inner support frame.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The cervical intervertebral fusion device, the inner support frame and the outer support frame can both play the role of reinforcing ribs, ensuring the mechanical strength of the cervical intervertebral fusion device and the stability under complex working conditions of the human body. By filling the buffer area between the inner support frame and the outer support frame with a lattice structure, the lattice structure filled between the inner support frame and the outer support frame can serve as a buffer, and the lattice structure can also withstand sufficient stress stimulation to promote bone growth, meeting the needs of cervical fusion surgery;

[0020] The stress stimulation piece filled in the cylindrical groove can be used as a stress stimulation source, and it moves by utilizing the inertial force applied during human movement. After the cervical intervertebral fusion device is implanted, the stress stimulation piece can release mechanical waves by impacting the inner wall of the cylindrical groove. The stress stimulation generated by the mechanical waves promotes the bone integration process and accelerates the patient's postoperative recovery. Specifically, when the stress stimulation piece is restricted in movement in the cylindrical groove, it moves up and down by utilizing the inertial force generated by human movement. The collision between the stress stimulation piece and the two ends of the cylindrical groove triggers mechanical waves, which will act on the surrounding tissues to generate stress stimulation to effectively promote bone growth and integration.

[0021] The present invention is further described below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of one viewing angle of a cervical intervertebral fusion device as a whole according to the present invention;

[0023] Figure 2 This is a schematic diagram of another viewing angle of the cervical intervertebral fusion device of the present invention;

[0024] Figure 3 A schematic diagram of an instrument slot and an instrument hole in a cervical intervertebral fusion device according to the present invention;

[0025] Figure 4 This is a schematic diagram of the inner and outer support frames of a cervical intervertebral fusion device according to the present invention;

[0026] Figure 5 This is a schematic diagram of one viewing angle of an inner support frame in a cervical intervertebral fusion device according to the present invention;

[0027] Figure 6 This is a schematic diagram of another viewing angle of the inner support frame in the cervical intervertebral fusion device of the present invention;

[0028] Figure 7 The figure is a cloud diagram of mechanical stress stimulation generated when the stress stimulation member in the cervical intervertebral fusion device described in the present invention collides with the two end surfaces of the cylindrical groove. DETAILED DESCRIPTION

[0029] The following description is used to fully explain the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0030] See also Figure 1 and 2The present invention provides a technical solution: a cervical intervertebral fusion device, wherein a plurality of bone ingrowth directions are arranged on the cervical intervertebral fusion device, the cervical intervertebral fusion device comprises an inner support frame 9 and an outer support frame 8 sleeved on the outer side of the inner support frame 9, a buffer area is reserved between the inner support frame 9 and the outer support frame 8, and the buffer area is filled with a lattice structure 2;

[0031] A cylindrical groove 1 is provided on the side wall of the inner support frame 9, a stress stimulation piece is movably provided in the cylindrical groove 1, and the cylindrical groove 1 is provided with an impact inner wall corresponding to the stress stimulation piece, and the stress stimulation piece is configured to move along with the cervical intervertebral fusion cage in at least one of the bone ingrowth directions.

[0032] The inner support frame 9 and the outer support frame 8 can both play the role of reinforcing ribs, ensuring the mechanical strength of the cervical intervertebral fusion device and the stability under complex working conditions of the human body. By filling the lattice structure 2 in the buffer area between the inner support frame 9 and the outer support frame 8, the lattice structure 2 filled between the inner support frame 9 and the outer support frame 8 can be used as a buffer, and the lattice structure 2 can also withstand sufficient stress stimulation to promote bone growth, meeting the needs of cervical fusion surgery;

[0033] The stress stimulation piece filled in the cylindrical groove 1 can be used as a stress stimulation source, and moves by utilizing the inertial force applied during human movement. After the cervical intervertebral fusion device is implanted, the stress stimulation piece can release mechanical waves by impacting the inner wall of the cylindrical groove 1. The stress stimulation generated by the mechanical waves promotes the bone integration process and accelerates the patient's postoperative recovery. Specifically, when the stress stimulation piece is restricted in movement in the cylindrical groove 1, it moves up and down through the inertial force generated by human movement. The collision between the stress stimulation piece and the two ends of the cylindrical groove 1 triggers mechanical waves, which will act on the surrounding tissues to generate stress stimulation to effectively promote bone growth and integration.

[0034] Regarding the specific structure between the inner support frame 9, the outer support frame 8 and the lattice structure 2, the lattice structure 2 is a body-centered cubic lattice structure 2 to provide better stability and greater porosity. The overall porosity of the cervical intervertebral fusion cage is about 70% to provide sufficient space for bone ingrowth.

[0035] Furthermore, the outer support frame 8 and the inner support frame 9 are provided with a plurality of surfaces in the circumferential direction, each of which is provided with the opening 3 , the opening 3 is arranged along the bone ingrowth direction, and the lattice structure 2 is filled in the opening 3 .

[0036] Furthermore, the opening 3 is a polygonal opening 3, and the corners of the opening 3 are all rounded. In one embodiment, the opening 3 is a square opening 3. The angles of the opening 3 are all rounded, which is used to reduce the stress concentration inside the cervical intervertebral fusion device. Further, the outer support frame 8 and the inner support frame 9 are polygonal cylindrical structures, and the corners of the polygonal cylindrical structures are all rounded.

[0037] Continue to see Figure 1 and 2 The inner side of the inner support frame 9 forms a bone graft window 6, and the bone graft window 6 is configured to be filled with autologous bone or allogeneic bone to promote postoperative bone integration. The axial and radial directions of the bone graft window 6 correspond to different bone growth directions, respectively.

[0038] For further information, see Figure 5 and 6 , the cylindrical groove 1 is arranged at the center position of each surface of the inner support frame 9 in the circumferential direction, and the opening 3 on each surface of the inner support frame 9 is located on both sides of the cylindrical groove 1;

[0039] The cylindrical groove 1 is closed at both ends in the axial direction, and an opening 7 suitable for the stress stimulation member to enter is formed on one side of the cylindrical groove 1 facing the inner support frame 9 .

[0040] Furthermore, the cylindrical groove 1 is arranged along the direction of the bone graft window 6, and the opening 7 on the cylindrical groove 1 and the two ends of the cylindrical groove 1 in the axial direction are arranged at intervals. When in use, the stress stimulation piece falls into the bottom of the cylindrical groove 1 after being filled in, and will not fall out during the implantation process. After implantation, the bone graft window 6 is filled with autologous bone or allogeneic bone to block the opening 7, so that the stress stimulation piece is completely located inside the cylindrical groove 1 and moves. Furthermore, the shortest distance between the opening 7 and the end face of the cylindrical groove 1 is not less than the radius of the stress stimulation piece. Furthermore, the size of the opening 7 is slightly larger than the size of the stress stimulation piece. This ensures that the stress stimulation piece can smoothly enter the cylindrical groove 1 through the opening 7 while preventing the stress stimulation piece from slipping out of the opening 7.

[0041] Further, the stress stimulation member is configured to be movable in the radial direction and the axial direction of the cylindrical slot 1. Specifically, the radial dimension of the stress stimulation member in the cylindrical slot 1 is smaller than the radial dimension of the cylindrical slot 1.

[0042] See also Figure 3 The outer support frame 8 is provided with an instrument slot 5 and an instrument hole 4 for implantation operation. The instrument slot 5 and the instrument hole 4 are both located on the same surface of the outer support frame 8 in the circumferential direction. The opening 3 on the surface is arranged in a manner to avoid the instrument slot 5 and the instrument hole 4.

[0043] The cervical intervertebral fusion cage is configured to be used in conjunction with the titanium plate, that is, the cervical intervertebral fusion cage itself does not contain a self-locking structure.

[0044] See also Figure 1-5 In one embodiment, the outer support frame 8 and the inner support frame 9 are each provided with four vertical surfaces in the circumferential direction. Specifically, the outer support frame 8 and the inner support frame 9 each include a first surface, a second surface, a third surface and a fourth surface sequentially connected along the circumferential direction, wherein the second surface and the fourth surface are arranged opposite to each other, the first surface and the fourth surface are arranged opposite to each other, and the spacing between the second surface and the fourth surface gradually increases in a manner close to the fourth surface to form the outer support frame 8 and the inner support frame 9 whose radial cross-sectional shape is approximately an isosceles trapezoid, the center of the fourth surface is bent outward in a manner away from the first surface, and the instrument slot 5 and the instrument hole 4 are both provided on the fourth surface;

[0045] The outer support frame 8 and the inner support frame 9 are both cylindrical structures with the same shape, and the outer support frame 8 and the inner support frame 9 are coaxially arranged;

[0046] In the radial direction of the bone graft window 6, the cylindrical groove 1 is larger than the size of the side wall of the inner support frame 9, and the two sides of the cylindrical groove 1 extend toward the inner side and the outer side of the inner support frame 9 respectively. In the axial direction of the bone graft window 6, the two ends of the cylindrical groove 1 are respectively flush with the two ends of the inner support frame 9;

[0047] The body-centered cubic lattice structure 2 has a unit cell side length of 1.5 mm and a wire diameter of 0.2 to 0.4 mm;

[0048] The bone graft window 6 is about 7.7 mm wide;

[0049] The cylindrical groove 1 is a cylindrical cylindrical groove 1, and the stress stimulation piece is a spherical stress stimulation piece made of titanium alloy;

[0050] The outer wall radius of the cylindrical groove 1 is 1 mm, the inner wall radius is 0.8 mm, the radius of the opening 7 of the cylindrical groove 1 facing the bone graft window 6 is 0.8 mm, and the radius of the stress stimulation element is 0.75 mm;

[0051] The cervical intervertebral fusion cage is made entirely of titanium alloy material.

[0052] In another embodiment, the radius of the stress stimulation element is 0.6 mm, so that it can be filled into the groove and is not easy to slide out.

[0053] The working principle and method of use are as follows: during implantation, the instrument slot 5 and the instrument hole 4 on the outer support frame 8 can assist the user in using the corresponding clamp for implantation;

[0054] When the stress stimulation piece needs to be filled, the stress stimulation piece can be clamped into the opening 7 on the side of the cylindrical groove 1 by tweezers. After being filled, the stress stimulation piece falls into the bottom of the cylindrical groove 1, so it will not fall out during the implantation process. After implantation, the autologous bone or allogeneic bone is filled into the bone graft window 6 to block the opening 7 on the side of the cylindrical groove 1, so that the stress stimulation piece is completely located in the cylindrical groove 1;

[0055] When the stress stimulation piece is restricted in movement in the cylindrical groove 1, it moves up and down through the inertial force generated by human body movement. The stress stimulation piece hits the top and bottom of the cylindrical groove 1 to induce mechanical waves. The mechanical waves will act on the surrounding tissues to generate stress stimulation to effectively promote bone growth and integration.

[0056] Since the cervical intervertebral fusion device itself does not contain a self-locking structure, the cervical intervertebral fusion device needs to be used in conjunction with a titanium plate when implanted.

[0057] In summary, the cervical intervertebral fusion device can be used as a stress stimulation source after the stress stimulation piece is filled in the cylindrical groove 1 on the inner support frame 9, and the inertial force applied during human body movement is used to move. After the intervertebral fusion device is implanted, the stress stimulation piece releases mechanical waves by impacting the wall of the cylindrical groove 1. The stress stimulation generated by the mechanical wave promotes the bone integration process and accelerates the patient's postoperative recovery.

[0058] The porosity and pore structure of the cervical interbody fusion device are reasonably designed and manufactured by selective laser melting technology to ensure the precise manufacturing of its porosity and pore shape. Its porosity is about 70% and the pore size is about 850 microns. The pore parameters are suitable for cell growth and differentiation and new bone growth. Sufficient surface porosity leaves space for bone ingrowth, which enhances the stability of the initial implantation.

[0059] The cervical intervertebral fusion device adopts an inner and outer double frame, and the inner and outer frames both play the role of reinforcing ribs, ensuring the mechanical strength of the intervertebral fusion device and the stability under complex working conditions of the human body. The inner and outer frames have appropriate stiffness, ensuring that while the outer frame bears the main stress, the internal lattice structure 2 can also bear sufficient profit stimulation to promote bone growth;

[0060] The cervical intervertebral fusion device uses titanium alloy as raw material, which has proven good biocompatibility, good corrosion resistance, light weight, and can provide a good biological environment for bone ingrowth. This material has been mature and widely used in the field of human implants, and will not be elaborated here.

[0061] It should be noted that the above mechanical stress stimulation promotes the principle of bone growth: mechanical force stimulation is often used in bone tissue engineering, mostly for bone defect repair or cartilage tissue repair. When mechanical force is applied, the macroscopic tissue force is transmitted to the micromechanical environment of the cell, thereby affecting the intracellular force. When osteoblasts are stimulated by mechanical stress, their activity is enhanced, prompting bone marrow mesenchymal stem cells to differentiate into osteoblasts, promoting bone growth and reconstruction. Appropriate mechanical force stimulation is very important for the distribution, metabolism, and homeostasis of osteoblasts [1]. The research of Kearney et al. [2] showed that cyclic strain can increase the bone-fat ratio through the Wnt pathway and upregulate the expression of palladin (an actin-related protein) to promote osteogenesis. In addition, the piezoelectric properties of bone enable it to generate electrical energy under the action of mechanical stress, thereby stimulating osteogenesis.

[0062] References:

[0063] 1. Huang,

[0064] 2. Kearney, EM, et al., Tensile Strain as a Regulator of MesenchymalStem Cell Osteogenesis. Annals of Biomedical Engineering, 2010.38(5):p.1767-1779.

[0065] The mechanical stress stimulation intensity generated by the stress stimulation piece: Based on the display dynamics method, the movement of the stress stimulation piece in the groove is simulated, and the peak stress generated when the stress stimulation piece hits the wall is observed. It is preliminarily estimated that in a non-violent exercise environment, the speed at which the stress stimulation piece hits the wall is limited to no more than 250mm / s. In this case, the peak stress generated by the stress stimulation piece hitting the wall is about 0.018MPa, see Figure 7 This stress is much smaller than the stress stimulation generated when the cervical interbody fusion device passively bears the movement of adjacent cervical segments. This stress stimulation is about several to tens of MPa. Therefore, this strength ensures that it has a certain promoting effect on bone fusion and also ensures that its size is within a safe range.

[0066] The embodiments described above are only used to illustrate the technical ideas and features of the present invention, and their purpose is to enable technicians in this field to understand the contents of the present invention and implement them accordingly. The patent scope of the present invention cannot be limited only by this embodiment, that is, any equivalent changes or modifications made according to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. A cervical intervertebral fusion device, wherein a plurality of bone ingrowth directions are arranged on the cervical intervertebral fusion device, characterized in that: The cervical intervertebral fusion device comprises an inner support frame (9) and an outer support frame (8) sleeved on the outer side of the inner support frame (9); a buffer area is reserved between the inner support frame (9) and the outer support frame (8); and the buffer area is filled with a lattice structure (2); A cylindrical groove (1) is arranged on the side wall of the inner support frame (9), a stress stimulation piece is movably arranged in the cylindrical groove (1), and the cylindrical groove (1) is provided with an impact inner wall corresponding to the stress stimulation piece, and the stress stimulation piece is arranged to move along with the cervical intervertebral fusion cage in at least one of the bone ingrowth directions.

2. A cervical intervertebral fusion cage according to claim 1, characterized in that: The inner support frame (9) and the outer support frame (8) are both provided with openings (3), the openings (3) are arranged along the bone ingrowth direction, and the lattice structure (2) is filled in the openings (3).

3. A cervical intervertebral fusion cage according to claim 2, characterized in that: The outer support frame (8) and the inner support frame (9) are provided with a plurality of faces in the circumferential direction, each face is provided with the opening (3), and the opening (3) is a polygonal opening (3), wherein the corners of the opening (3) are all rounded.

4. A cervical intervertebral fusion cage according to claim 1, characterized in that: The lattice structure (2) is a body-centered cubic lattice structure (2), and the overall porosity of the cervical intervertebral fusion cage is approximately 70%.

5. A cervical intervertebral fusion cage according to claim 1, characterized in that: The inner side of the inner support frame (9) forms a bone graft window (6), and the bone graft window (6) is configured to be filled with autologous bone or allogeneic bone. The axial direction and radial direction of the bone graft window (6) correspond to different bone ingrowth directions respectively.

6. A cervical intervertebral fusion cage according to claim 5, characterized in that: The cylindrical groove (1) is arranged at the center position of each surface of the inner support frame (9) in the circumferential direction, the cylindrical groove (1) is closed at both ends in the axial direction, and an opening (7) suitable for the stress stimulation component to enter is opened on the side of the cylindrical groove (1) facing the bone grafting window (6).

7. A cervical intervertebral fusion cage according to claim 6, characterized in that: The cylindrical groove (1) is arranged along the direction of the bone grafting window (6), the opening (7) on the cylindrical groove (1) and the two ends of the cylindrical groove (1) in the axial direction are arranged at intervals, and the size of the opening (7) is slightly larger than the size of the stress stimulation component.

8. A cervical intervertebral fusion cage according to claim 7, characterized in that: The dimension of the stress stimulation element in the radial direction of the cylindrical groove (1) is slightly smaller than the radial dimension of the cylindrical groove (1).

9. A cervical intervertebral fusion cage according to claim 1, characterized in that: The cervical intervertebral fusion cage is configured to be used in conjunction with a titanium plate.

10. A cervical intervertebral fusion cage according to claim 5, characterized in that: The cervical intervertebral fusion device is made of titanium alloy material as a whole, the cylindrical groove (1) is a cylindrical cylindrical groove (1), and the stress stimulation piece is a spherical stress stimulation piece; In the radial direction of the bone graft window (6), the size of the columnar groove (1) is larger than the size of the side wall of the inner support frame (9), wherein the two sides of the columnar groove (1) respectively extend toward the inner side and the outer side of the inner support frame (9), and in the axial direction of the bone graft window (6), the two ends of the columnar groove (1) are respectively flush with the two ends of the inner support frame (9).

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