Spinal fusion cage with elastic and porous structure

Abstract

The present invention relates to a cage inserted between adjacent vertebrae for use in vertebral fusion, comprising: a solid structure formed in a solid form that forms the outer periphery of the upper and lower surfaces of the cage to provide structural stability to the cage; an elastic structure inserted inside the solid structure to provide elasticity against compressive loads; and a porous structure located on the upper and lower surfaces of the cage to form a contact surface that contacts the vertebrae and to enhance bone fusion with the vertebrae. By providing elasticity against compressive loads to prevent the phenomenon of subsidence in which the cage burrows into the vertebrae, the invention has the effect of enhancing bone fusion with the vertebrae for elderly spinal surgery patients with low bone density.

Description

Technology Field

[0001] The present invention relates to a spinal fusion cage having an elastic and porous structure, and more specifically, to a spinal fusion cage having a structure that provides elasticity against compressive loads to prevent the subsidence phenomenon in which the cage burrows into the vertebral body, and can enhance bone fusion with the vertebrae for elderly spinal surgery patients with low bone density. Background Technology

[0002] The spine forms the vertical axis of the body and consists of 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 sacrum, and 4 coccyx, and is made up of intervertebral discs, which are disc-shaped cartilaginous structures that connect the vertebrae.

[0003] Recently, the incidence of lumbar degenerative diseases, such as spinal stenosis and degenerative spine, has been increasing due to the aging society. In such cases, bone fusion surgery is widely used to remove displaced and deformed intervertebral bodies, insert a spinal fusion cage to restore the original disc height of the vertebral bodies, and fuse the vertebral bodies into one.

[0004] However, conventional spinal fusion surgery has the following problems.

[0005] 1. Settlement problem due to difference in elastic modulus after surgery

[0006] Conventional simple titanium cages have been widely used due to their excellent biocompatibility and stability.

[0007] The elastic modulus of a simple metallic titanium alloy is 110 GPa, and the elastic modulus of the cancellous bone of the vertebral body into which the cage is inserted is 1.34 GPa, showing a difference of about 100 times in elastic modulus.

[0008] Consequently, a phenomenon called subsidence is occurring in clinical practice after surgery, where the rigid metal cage penetrates into the relatively weak vertebral body. Since this subsidence results in a reduction in the height of the vertebral body, it leads to the recurrence of spinal stenosis and becomes a cause for revision surgery. (Chen, Yu, Subsidence of Titanium Mesh Cage: A Study Based on 300 Cases, Journal of Spinal Disorders & Techniques: October 2008 - Volume 21 - Issue 7 - p489-492)

[0010] 2. Problems with reduced bone union

[0011] Osteoporosis is the most common metabolic bone disease among elderly patients, and as the elderly population increases, life expectancy increases, and quality of life improves, active surgical treatment for such degenerative spinal diseases has become necessary.

[0012] However, due to the nature of spinal cages generally made of metal, the bone generated through the cage interface after the procedure is limited. The reduced rate of bone formation on the cage surface can lead to reduced initial fixation strength and become a long-term issue; it is reported to be a significant problem, particularly in patients with low bone density or those with specific constitutions that hinder bone fusion.

[0013] Therefore, it is required to establish a porous structure suitable for the bone density status of patients with varying bone densities, and for elderly spinal surgery patients with low bone density, the contact surface between the bone and the cage interface must be anatomically correct and have a wide contact area to improve bone ingrowth, so improvement is required in this regard. Prior art literature

[0014] Korean Registered Patent No. 10-0645377 The problem to be solved

[0015] The present invention was devised to solve the above-mentioned problems, and aims to provide a spinal fusion cage that solves the subsidence problem caused by the difference in elastic modulus between the cage and the bone after surgery, and is applicable to patients with various bone densities, including elderly patients with osteoporosis, by ensuring that the contact surface between the bone and the cage interface is anatomically aligned through a porous structure suited to the patient's bone density condition, and thereby improves bone ingrowth through a large contact area. means of solving the problem

[0016] To achieve the above objectives, the present invention provides a spinal fusion cage that is inserted between adjacent vertebrae and used for vertebral fusion, comprising: a solid structure formed in a solid form to provide structural stability to the cage and an outer periphery of the upper and lower surfaces of the cage; an elastic structure inserted inside the solid structure and providing elasticity against compressive loads; and a porous structure located on the upper and lower surfaces of the cage to form a contact surface in contact with the vertebrae and to improve bone fusion with the vertebrae, the cage being composed of three parts: a solid structure, an elastic structure, and a porous structure.

[0017] It is preferable that the above solid structure be formed to have a smooth, streamlined shape to prevent damage to the blood vessel portion when inserted between vertebrae.

[0018] In addition, the solid structure includes a rear connection portion for connecting a surgical instrument, and a groove and a female screw hole for connecting a surgical instrument are formed in the rear connection portion.

[0019] Meanwhile, the elastic structure has a shape in which multiple perforations penetrating in the horizontal direction are formed to provide elasticity against compressive loads in the vertical or diagonal direction, thereby reducing the difference in elastic modulus with the vertebral body.

[0020] The above perforations are formed in a trapezoidal shape and can be formed continuously in the up-down, left-right, or diagonal directions.

[0021] In this case, the elastic structure may have a circular reinforcing member formed at the apex of the trapezoidal shape forming the hole.

[0022] In addition, the above-mentioned perforations are formed in any one of the shapes of a trapezoid, rhombus, circle, ellipse, triangle, pentagon, hexagon, or octagon, or a combination thereof, and can be formed continuously in the up-down, left-right, or diagonal directions.

[0023] In the present invention, the solid structure, elastic structure, or porous structure is manufactured from metal powder or polymer powder, and the metal is characterized by being at least one of titanium, titanium alloy, cobalt-chromium, cobalt-chromium alloy, tantalum, tantalum alloy, Peek, and stainless steel.

[0024] The above porous structure is characterized by having a porosity of 20% to 80%.

[0025] In the present invention, the elastic structure and the porous structure may have a bone insertion space formed in the center for filling with bone graft material. Effects of the invention

[0026] According to the present invention as described above, by including an elastic structure that provides elasticity against compressive loads, it is possible to solve the problem of subsidence caused by the difference in elastic modulus between the cage and the bone after surgery.

[0027] In addition, to be applicable to patients with varying bone densities, including elderly patients with osteoporosis, the contact surface between the bone and the cage interface is anatomically aligned through a porous structure that matches the patient's bone density condition, and the large contact area can have the effect of improving bone ingrowth. Brief explanation of the drawing

[0028] FIG. 1 is a perspective view illustrating a first embodiment of the spinal fusion cage of the present invention. FIG. 2 is a rear perspective view illustrating a first embodiment of the spinal fusion cage of the present invention. FIG. 3 is an exploded perspective view illustrating a first embodiment of the spinal fusion cage of the present invention. FIG. 4 is a side view illustrating a first embodiment of the spinal fusion cage of the present invention. FIG. 5 is a perspective view illustrating a second embodiment of the spinal fusion cage of the present invention. FIG. 6 is an exploded perspective view illustrating a second embodiment of the spinal fusion cage of the present invention. FIG. 7 is a perspective view illustrating a third embodiment of the spinal fusion cage of the present invention. FIG. 8 is an exploded perspective view illustrating a third embodiment of the spinal fusion cage of the present invention. FIG. 9 is a side view illustrating a third embodiment of the spinal fusion cage of the present invention. FIG. 10 is an illustrative diagram showing various embodiments of the elastic structure and porous structure of the present invention. Specific details for implementing the invention

[0029] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0030] FIG. 1 is a perspective view illustrating a first embodiment of the spinal fusion cage of the present invention, FIG. 2 is a rear perspective view illustrating a first embodiment of the spinal fusion cage of the present invention, FIG. 3 is an exploded perspective view illustrating a first embodiment of the spinal fusion cage of the present invention, and FIG. 4 is a side view illustrating a first embodiment of the spinal fusion cage of the present invention.

[0031] The vertebral fusion cage (100) according to the first embodiment of the present invention is characterized by being composed of three parts: a solid structure (110) (114), an elastic structure (120), and a porous structure (130).

[0032] The above solid structure (110)(114) is intended to provide structural stability to the cage (100) and is composed of an upper solid structure (110) and a lower solid structure (114) to form the outer edges of the upper and lower surfaces of the cage (100), and the upper solid structure (110) and the lower solid structure (114) may be formed symmetrically.

[0033] It is preferable that these solid structures (110) (114) be formed to have a smooth, streamlined shape to prevent damage to the blood vessel portion when inserted between the vertebrae.

[0034] As shown in FIG. 1, in the first embodiment of the present invention, the solid structure (110) has a roughly rounded shape and the edge portion is rounded to facilitate insertion between vertebrae and to prevent damage to the blood vessel portion during insertion.

[0035] Additionally, the solid structure (110) (114) includes a rear connection part (112) for connecting a surgical instrument.

[0036] That is, a surgical instrument that is coupled to the cage (100) is used for spinal fusion surgery, and since the connection with such a surgical instrument must be made in a solid form, the rear connection part (112) for connecting the surgical instrument is made of a solid structure.

[0037] A groove and a female screw hole (112a) for connecting a surgical instrument are formed in the rear connection part (112) above.

[0038] Meanwhile, in the central part of the cage (100), an elastic structure (120) is provided that is inserted between the upper solid structure (110) and the lower solid structure (114) and provides elasticity against compressive load.

[0039] Meanwhile, the above elastic structure (120) is designed to reduce the difference in elastic modulus with the vertebrae and has a shape capable of providing elasticity against compressive loads in the vertical or diagonal direction.

[0040] Here, the elastic modulus (Young's Modulus, Elastic Modulus) is a value representing the stiffness of a material. Since stress and strain are directly proportional within the elastic limit (Hook's Law), the elastic modulus refers to the proportionality constant. Therefore, a high elastic modulus indicates small deformation, and small deformation implies high material strength. Conversely, a low elastic modulus indicates large deformation, and large deformation implies low material strength.

[0041] Therefore, when a cage (100) having a high elastic modulus compared to the elastic modulus of the patient's bone is inserted between the vertebrae, a stress shielding phenomenon in which the patient's bone density is reduced by the strong cage (100) and a sinking down phenomenon of the bone may occur. Thus, it is desirable that the elastic modulus of the cage (100) be configured to be close to the elastic modulus of the patient's bone.

[0042] Accordingly, the spinal fusion cage of the present invention is equipped with the elastic structure (120) for reducing the difference in elastic modulus with the spinal bone, and the elastic structure (120) has a shape in which a plurality of perforations are formed that penetrate in the horizontal direction to reduce the difference in elastic modulus with the vertebral body.

[0043] The above-mentioned perforations (122) are preferably formed in a trapezoidal shape to provide elasticity against compressive loads in the vertical or diagonal direction, and can be formed continuously in the vertical, horizontal, or diagonal directions.

[0044] These perforations (122) are formed to penetrate the cage (100) in a direction that can have elasticity against compressive loads, that is, in a roughly horizontal direction.

[0045] In the first embodiment of the present invention, the perforation (122) is shown to be in a trapezoidal shape, specifically a rhombus shape; however, the present invention is not limited thereto, and the perforation may be formed in any one of the shapes including a trapezoidal shape, a rhombus shape, a circle, an ellipse, a triangle, a pentagon, a hexagon, or an octagon.

[0046] In addition, it may be composed of a combination of trapezoids, rhombuses, circles, ellipses, triangles, pentagons, hexagons, and octagons. In this case as well, the perforations are formed continuously in the up-down, left-right, or diagonal directions, thereby enabling elasticity against compressive loads in the up-down or diagonal directions.

[0047] Therefore, when the cage (100) equipped with the above elastic structure (120) is inserted between the vertebrae, the cage gains elasticity against compressive loads, thereby preventing the phenomenon of subsidence where it penetrates into the vertebrae.

[0048] Meanwhile, the upper and lower surfaces of the cage (100) forming the contact surface with the vertebral body are provided with porous structures (130) (132) to improve bone fusion with the vertebral body.

[0049] The above porous structure (130)(132) is designed to increase the contact area between the bone and the cage interface to improve bone ingrowth, and for elderly spinal surgery patients with low bone density, the contact surface between the bone and the cage interface is anatomically aligned, and the increased contact area has the effect of improving initial fixation strength.

[0050] Osteoporosis is the most common metabolic bone disease among elderly patients; however, due to the nature of metal spinal cages, there is a disadvantage in that bone formation passing through the cage interface after the procedure is limited. The reduced rate of bone formation at the cage surface can lead to decreased initial fixation strength and become a long-term issue. This can be a significant problem, particularly in patients with low bone density or those with specific constitutions that hinder bone fusion; therefore, the establishment of a porous structure tailored to the patient's bone density status is required.

[0051] The porous structure (130)(132) has a plurality of pores. These pores may be configured to be formed in a disorderly manner at any location, but preferably, they may be configured in an orderly manner in a certain shape. Regarding the shape of the pores, it is not limited to a specific concept, and they may be configured in any shape.

[0052] The above porous structure (130)(132) is preferably made to have a porosity of 20% to 80% to have a porous structure suitable for the bone density condition of patients with various bone densities, and can be made in various forms as shown in FIG. 10.

[0053] FIG. 10 is an illustrative diagram showing various embodiments of the elastic structure and porous structure of the present invention.

[0054] As illustrated in FIG. 10, the elastic structure and porous structure of the present invention are not limited to any specific shape and are formed in various shapes, but it is preferable that they be arranged in an orderly manner by continuously and repeatedly forming a certain shape.

[0055] In the present invention, the elastic structure (120) and the porous structure (130) may have a bone insertion space formed in the center that can be filled with bone graft material.

[0056] In the present invention, the solid structure (110), elastic structure (120), or porous structure (130) is manufactured from metal powder or polymer powder, and the metal may be selected from the group consisting of titanium, titanium alloy, cobalt-chromium, cobalt-chromium alloy, tantalum, tantalum alloy, Peek, and stainless steel.

[0057] FIG. 5 is a perspective view illustrating a second embodiment of the spinal fusion cage of the present invention, and FIG. 6 is an exploded perspective view illustrating a second embodiment of the spinal fusion cage of the present invention.

[0058] The spinal fusion cage illustrated in FIGS. 5 and 6 is a lateral approach cage, and the spinal fusion cage in the present invention may have various forms depending on the surgical method, and the first embodiment illustrated in FIGS. 1 to 4 is an anterior approach cage, and the second embodiment is a lateral approach cage.

[0059] The second embodiment also consists of three parts: a solid structure (210) that forms the outer periphery of the upper and lower surfaces of the cage to provide structural stability to the cage (200) and is formed in a solid form; an elastic structure (220) that is inserted inside the solid structure (210) and provides elasticity against compressive load; and a porous structure (230) that is located on the upper and lower surfaces of the cage to form a contact surface that contacts the vertebral body and improves bone fusion with the vertebral body.

[0060] The above solid structure (210), elastic structure (220), and porous structure (230) differ only in shape from the first embodiment described above, but the functional configuration in which the elastic structure (220) is inserted inside the solid structure (210) and the porous structure (230) is disposed on the upper and lower surfaces of the elastic structure (220) is the same, so a detailed description thereof will be omitted.

[0061] Meanwhile, FIG. 7 is a perspective view illustrating a third embodiment of the spinal fusion cage of the present invention, FIG. 8 is an exploded perspective view illustrating a third embodiment of the spinal fusion cage of the present invention, and FIG. 9 is a side view illustrating a third embodiment of the spinal fusion cage of the present invention.

[0062] The third embodiment of the present invention is a rear access cage, and the third embodiment also consists of three parts: a solid structure (310) formed in a solid form to form the outer periphery of the upper and lower surfaces of the cage to provide structural stability to the cage (300); an elastic structure (320) inserted inside the solid structure (310) to provide elasticity against compressive load; and a porous structure (330) located on the upper and lower surfaces of the cage to form a contact surface that contacts the vertebral body and to improve bone fusion with the vertebral body.

[0063] The above solid structure (310), elastic structure (320), and porous structure (330) differ only in shape from the first embodiment described above, but the functional configuration in which the elastic structure (320) is inserted inside the solid structure (310) and the porous structure (330) is disposed on the upper and lower surfaces of the elastic structure (320) is the same.

[0064] Meanwhile, the elastic structure (320) has a shape in which a plurality of holes (322) are formed that penetrate in the horizontal direction to reduce the difference in elastic modulus with the vertebra.

[0065] The above-mentioned perforations (322) are preferably formed in a trapezoidal shape to provide elasticity against compressive loads in the vertical or diagonal direction, and can be formed continuously in the vertical, horizontal, or diagonal directions.

[0066] In the third embodiment, the elastic structure (320) may have a circular reinforcing member (326) formed at the apex of the trapezoidal shape forming the perforation (322).

[0067] The above reinforcing members (326) are formed at the vertices forming each trapezoidal shape, thereby reinforcing the rigidity so that the cage (300) can withstand a greater load when subjected to a compressive load.

[0068] The spinal fusion cage of the present invention includes an elastic structure (320) that provides elasticity against compressive loads, thereby having the effect of solving the subsidence problem caused by the difference in elastic modulus between the cage and the bone after surgery.

[0069] In addition, to be applicable to patients with varying bone densities, including elderly patients with osteoporosis, the contact surface between the bone and the cage interface is anatomically aligned through a porous structure that matches the patient's bone density condition, and the large contact area can have the effect of improving bone ingrowth.

[0070] Although the present invention has been described above with reference to embodiments, various changes and modifications can be made by those skilled in the art to which the present invention pertains. Such changes and modifications are considered to be within the scope of the present invention as long as they do not depart from the technical concept provided by the present invention. Accordingly, the scope of rights of the present invention should be determined by the claims set forth below. Explanation of the symbols

[0071] 100: Vertebral fusion cage 110: Upper solid structure 112: Rear connection part 112a: Female screw hole 114: Lower solid structure 120: Elastic structure 122: Perforation 130: Porous structure

Claims

Claim 1 A cage inserted between two adjacent vertebral bodies for use in vertebral fusion, comprising: a solid structure formed on the upper and lower surfaces of the cage to provide structural stability to the cage and having a solid form; an elastic structure inserted inside the solid structure and providing elasticity against compressive loads; and a porous structure located on the upper and lower surfaces of the cage to enhance bone fusion with the vertebral bodies.Including, it is composed of three parts: a solid structure, an elastic structure, and a porous structure; the elastic structure is formed in an elliptical shape when viewed along the direction passing through the two adjacent vertebrae, has two through holes penetrating the elliptical shape surrounding two foci on the major axis of the elliptical shape, and has a shape in which multiple perforations are formed penetrating horizontally perpendicular to the direction passing through the two adjacent vertebrae to provide elasticity against compressive loads in the vertical or diagonal direction and to reduce the difference in elastic modulus with the vertebrae; the solid structure is formed in a ring shape along the outer edge of the upper and lower surfaces of the elastic structure from the outside of the elastic structure through a part of the solid structure, and is inserted into the interior of the elastic structure in an alphabet 'E' shape through one side wall of the elastic structure through the remainder of the solid structure, and is formed as a rear connection part having a groove and a female screw hole for connecting surgical instruments while surrounding the two through holes of the elastic structure; the porous structure is located on the upper and lower surfaces of the elastic structure and is on the ring-shaped solid structure A spinal fusion cage characterized by being surrounded by, having two open holes corresponding to each of the two through holes of the elastic structure, and in contact with two adjacent vertebrae together with the ring-shaped solid structure, wherein the solid structure and the porous structure have a sawtooth shape of the porous structure aligned with the sawtooth shape of the solid structure along the occupied area of ​​the solid structure and the porous structure on the upper and lower surfaces of the elastic structure, and wherein the elastic structure and the porous structure have a bone insertion space capable of filling with bone graft material through the two through holes of the elastic structure and the two open holes of the porous structure. Claim 2 A spinal fusion cage according to claim 1, characterized in that the solid structure is formed to have a soft, streamlined shape to prevent damage to the blood vessel portion when inserted between vertebrae. Claim 3 delete Claim 4 delete Claim 5 A spinal fusion cage according to claim 1, characterized in that the perforations are formed in a trapezoidal shape and are formed continuously in the up-down, left-right, or diagonal directions. Claim 6 delete Claim 7 delete Claim 8 A spinal fusion cage according to claim 1, wherein the solid structure, elastic structure, or porous structure is manufactured from metal powder or polymer powder, and the metal is at least one of titanium, titanium alloy, cobalt-chromium, cobalt-chromium alloy, tantalum, tantalum alloy, PEEK, and stainless steel. Claim 9 A spinal fusion cage according to claim 1, characterized in that the porous structure has a porosity of 20% to 80%. Claim 10 delete

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