Artificial lumbar intervertebral disc

Abstract

The present invention provides a lateral approach artificial intervertebral disc that inserts the artificial intervertebral disc from the side of the spine rather than the front of the spine, prevents damage to blood vessels and other organs that occurs in the anterior approach artificial intervertebral disc inserted from the front, shortens the operation time, prevents the artificial intervertebral disc from falling off, and can improve the surgical prognosis. In an artificial intervertebral disc inserted between two adjacent vertebrae, it includes an upper plate that contacts the upper vertebra, a lower plate that contacts the lower vertebra, and an inserter that is inserted between the upper plate and the lower plate and rotates the upper plate at a set angle with respect to the lower plate. The upper plate and the lower plate are characterized in that upper blade portions and lower blade portions extending in the insertion direction and the installer direction are formed in a state where the inserter is inserted.

Description

Technical Field

[0001] The present invention relates to an artificial lumbar intervertebral disc, and more particularly to an artificial lumbar intervertebral disc that can be inserted from the lateral side of the vertebral body (Lateral Approach).

Background Art

[0002] The spinal column consists of 32 to 35 vertebrae that make up the body and intervertebral discs (intervertebral disk or disk) between the vertebrae, and is the central part of the body that connects the skull at the upper end and the pelvis at the lower end.

[0003] The vertebrae consist of 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 sacral vertebrae, and 3 to 5 coccygeal vertebrae from top to bottom. In adults, however, the 5 sacral vertebrae fuse into 1 sacrum, and the 3 to 5 coccygeal vertebrae fuse into 1 coccyx.

[0004] Between the vertebral bodies, there is a cartilaginous substance called the intervertebral disc. This cartilaginous substance is soft and flexible fibrocartilage. It forms cartilaginous joints to assist the flexible movement of the spine, plays a role like a ligament that fixes the spine, absorbs and reduces the impact applied to the vertebral body. The intervertebral disc is composed of a fibrous annulus fibrosus on the outside and a nucleus pulposus made of a gel-like substance on the inside, which helps maintain strength and disperse stress. That is, the intervertebral disc absorbs the body's load and impact between each vertebra except for a part of the cervical vertebrae, undertakes a buffering role of dispersing the impact like a spring, and holds the vertebrae so that they do not dislocate, separates the two vertebrae so that the spinal nerve is not compressed, makes the range of the spinal joint cavity smooth, and smooths the movement of each vertebra.

[0005] Since such an intervertebral disc buffers or transmits the load and impact applied in the vertical direction, various diseases such as spinal stenosis, osteophyte formation, intervertebral disc herniation, and nerve root compression occur.

[0006] Conventionally, as one of the treatment methods for treating severe spinal diseases, there is spinal fusion. Such spinal fusion is a surgical method that removes the intervertebral disc and instead inserts a cage to fix adjacent vertebral bodies to each other.

[0007] When such spinal fusion is performed on the lumbar spine, depending on the insertion direction of the cage, it can be classified into posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), lateral lumbar interbody fusion (LLIF), oblique lumbar interbody fusion (OLIF), anterior lumbar interbody fusion (ALIF), etc.

[0008] Posterior lumbar interbody fusion (PLIF) is a method in which an incision is made along the center line of the spine, the spine is opened so that all vertebral bodies are exposed, a part of the posterior side of the vertebra is removed, and then the intervertebral disc is removed and a PLIF cage is inserted.

[0009] Posterior lumbar interbody fusion (PLIF) is the oldest method of spinal fusion and is a necessary method when performing spinal fusion of two or three segments. However, during the surgical process, there is a high possibility of adhesion to nerves, ligaments, and muscles, the incision area is large, the healing time is long, and in some people, there are disadvantages of large sequelae.

[0010] The PLIF cage has a pair of small cages arranged on both the left and right sides and is the smallest of the cages used in all spinal fusions.

[0011] Transforaminal lumbar interbody fusion (TLIF) is a surgical method in which small incisions are made along both sides of the spinal muscles to minimally expose the vertebral body, and then the spinal joint area is removed in the direction where the neural foramen exits while inserting a TLIF cage. This surgical technique has the advantages of less bleeding and shorter surgical time, so it is suitable for single-segment surgery. However, when various site surgeries are required, posterior lumbar interbody fusion (PLIF) surgery must be performed. The TLIF cage is almost arc-shaped. It is inserted into the vertebral body and rotated so that the convex part of the TLIF cage faces the ventral side. The TLIF cage is larger than the PLIF cage but smaller than the lateral lumbar interbody fusion (LLIF) cage or anterior lumbar interbody fusion (ALIF) cage described later in terms of the supporting area.

[0012] Anterior lumbar interbody fusion (ALIF) has various advantages such as rapid surgical recovery and no risk of adhesion. However, since it is performed by making an incision in the front (ventral side) and separating the internal organs to approach the spine, it has the disadvantage of requiring highly skilled techniques. The ALIF cage has the advantage of having the largest supporting area among all spinal fixation cages.

[0013] Lateral lumbar interbody fusion (LLIF) was developed to overcome the disadvantages of ALIF, PLIF, and TLIF. Lateral lumbar interbody fusion proceeds with the surgery through a flank incision, so it has the advantages of further widening the interval between the stenosis sites of the spine compared to the conventional surgery of incising the back and having almost no damage to the surrounding tissues. However, since there are the psoas muscle and peritoneum around the surgical path, there are problems such as femoral muscle paralysis due to surgical errors. The LLIF cage is smaller than the ALIF cage but larger than the PLIF cage and TLIF cage.

[0014] Compared with such lateral vertebral fixation, a safer and more effective surgical method is oblique lateral vertebral fixation (OLIF (Oblique Lumbar Interbody Fusion) or ATP (Anterior To Psoas) fusion). The oblique lateral vertebral fixation has the advantage that the surgical path is made in an oblique direction from the flank, and it is possible to perform surgery even between the fourth lumbar vertebra (L4) and the fifth lumbar vertebra (L5) which are difficult to operate on by DLIF due to the psoas muscle and peritoneum. Also, the possibility of damaging the nerves which is a problem in lateral vertebral fixation is significantly less.

[0015] However, in the above-mentioned spinal fixation, since the upper and lower vertebral bodies are connected to each other, from the patient's perspective, one of the corresponding intervertebral discs is lost, and the mobility that the intervertebral disc was responsible for is lost.

[0016] An artificial intervertebral disc was developed to solve such problems of loss of mobility. The surgical method of the artificial intervertebral disc is first to remove the damaged spinal intervertebral disc, then create a space between two adjacent vertebrae, and insert the artificial intervertebral disc into that space. The artificial intervertebral disc itself has the advantage that it can maintain mobility even after surgery because the upper and lower plates can move within a certain angular range.

[0017] In conventional artificial intervertebral disc replacement, since the posterior arch composed of a pair of pedicles, the superior and inferior articular processes extending backward from the pedicles, the lamina, and the spinous process is located on the dorsal side, the surgery was performed from the anterior approach after making an abdominal incision and controlling the peritoneum and moving the organs.

[0018] More specifically, first, the patient is placed in a state where the front of the body is facing up, the anterior abdomen of the trunk is incised, and a surgical path is secured to the spine while avoiding the organs. Then, a part of the anterior longitudinal ligament is incised on the anterior side of the trunk of the spine. When the anterior longitudinal ligament is incised, the intervertebral disc between the vertebrae is exposed. This intervertebral disc is removed through a surgical mechanism, and an artificial intervertebral disc is inserted in the position of the intervertebral disc.

[0019] Therefore, the conventional surgical method using an artificial intervertebral disc has the problems that the incision site becomes large and the surgery has to be performed while avoiding organs, so there is a possibility of damaging the surrounding blood vessels and tissues, and the operation time increases. In particular, since the anterior longitudinal ligament is incised, there is an even greater problem that the postoperative prognosis of the patient is not good.

[0020] Another problem caused by the incision of the anterior longitudinal ligament is that although the original intervertebral disc of the human body is blocked by the anterior longitudinal ligament, when a load is applied in the direction of the long axis of the human body to the artificial intervertebral disc inserted in the state where the anterior longitudinal ligament is incised, a force is transmitted forward and the artificial intervertebral disc may fall out forward.

[0021] In addition, there is a problem that excessive force is transmitted to the posterior joints due to the removal of the anterior longitudinal ligament, which may cause other spinal deformities.

Summary of the Invention

Problems to be Solved by the Invention

[0022] The present invention is for solving the above problems, and provides a lateral approach artificial intervertebral disc in which the artificial intervertebral disc is inserted into the lateral side of the spine rather than the front of the spine, preventing damage to blood vessels and other organs that may occur in the anterior approach artificial intervertebral disc inserted from the front, shortening the operation time, preventing the artificial intervertebral disc from falling off, and improving the surgical prognosis. The purpose is to provide an artificial lumbar intervertebral disc.

Means for Solving the Problems

[0023] The present invention for achieving the above object is an artificial intervertebral disc inserted between two adjacent vertebrae, including an upper plate in contact with the upper vertebra; a lower plate in contact with the lower vertebra; and an inserter inserted between the upper plate and the lower plate to rotate the upper plate relative to the lower plate by a set angle. The upper plate and the lower plate are characterized in that upper blade portions and lower blade portions extending along a horizontal axis are formed in a state where the inserter is inserted, and it is an artificial lumbar intervertebral disc.

[0024] The upper plate and the lower plate are characterized in that the thickness in the front is larger than that in the rear.

[0025] In addition, an upper keel part and a lower keel part are formed along the horizontal axis on the outer surface of the upper plate of the upper plate and the outer surface of the lower plate of the lower plate, respectively.

[0026] In addition, a plurality of upper protrusions and lower protrusions are formed on the outer surface of the upper plate of the upper plate and the outer surface of the lower plate of the lower plate.

[0027] In addition, the upper protrusion and the lower protrusion each have a quadrangular pyramid shape having a quadrangular cross section composed of four line segments perpendicular to the horizontal axis and the front-rear axis.

[0028] In addition, the inserter has an upper dome part formed at the upper part, a first axis rotation part formed at the lower part, an upper concave groove formed on the upper plate corresponding to the upper dome part and slidingly contacting the upper dome part, and a second axis rotation part contacting the first axis rotation part is formed on the lower plate.

[0029] In addition, the upper dome part is formed in an elliptical hemispherical shape with a major axis arranged on the horizontal axis and a minor axis arranged on the front-rear axis. When the upper dome part and the upper concave groove come into contact and move, the upper plate performs lateral bending and flexion-extension motion with respect to the lower plate.

[0030] In addition, the maximum depth of the upper concave groove is formed smaller than the maximum height of the upper dome part.

[0031] Further, an upper stopper is formed around the upper concave groove, and the upper stopper contacts the upper surface of the inserter of the inserter body formed around the upper dome portion, whereby the angular momentum of the upper plate is restricted.

[0032] Further, the lower surface of the inserter of the inserter body is formed in a flat state such that the thickness decreases from the upper surface of the inserter toward the end of the inserter body from the upper dome portion.

[0033] Further, the first-axis rotating portion is a lower outer protrusion formed on the lower surface of the inserter, the second-axis rotating portion is a lower outer groove formed in the lower plate, and the lower outer groove is formed in an arc shape.

[0034] Further, a lower central protrusion is formed at the center of the lower surface of the inserter, and a lower central groove corresponding to the lower central protrusion is formed in the lower plate.

Advantages of the Invention

[0035] According to the embodiment of the present invention configured as described above, it is possible to provide an artificial lumbar intervertebral disc that enables insertion laterally into the spine, prevents damage to blood vessels and other organs during surgery, and can shorten the surgery time.

[0036] Further, if such an artificial intervertebral disc is inserted, the anterior longitudinal ligament is not removed, so there is an advantage that detachment of the artificial intervertebral disc after surgery is prevented and the function of the anterior longitudinal ligament can be maintained as it is.

[0037] Further, since it is inserted laterally, there is an advantage that damage to organs can be prevented, the surgery time can be shortened, and the amount of bleeding during the surgery of the patient can be suppressed.

Brief Description of the Drawings

[0038]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Best Mode for Carrying Out the Invention

[0039] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. When adding reference numerals to the components of the following drawings, as long as they are the same components, even if they are shown on other drawings, the same reference numerals are used as much as possible, and detailed descriptions of known functions and configurations that may unnecessarily obscure the gist of the present invention are omitted.

[0040] Figure 1 shows an artificial intervertebral disc 10 according to an embodiment of the present invention. First, the directions are defined. The abdominal direction of the patient is referred to as the anterior direction, and the back direction of the patient is referred to as the posterior direction. Therefore, the anterior and posterior directions are opposite to each other. And the direction in which the artificial intervertebral disc 10 is inserted during the operation is referred to as the insertion direction, and the direction opposite to the insertion direction and in which a mechanism (not shown) for gripping the artificial intervertebral disc 10 is located is referred to as the installer direction.

[0041] And the virtual straight line determined in the anterior and posterior directions is referred to as the anterior to posterior axis, and the virtual straight line determined in the installer direction and the insertion direction is referred to as the lateral axis. Also, the vertical direction of the human body is referred to as the vertical axis. Therefore, the anterior to posterior axis, the lateral axis, and the vertical axis are perpendicular to each other.

[0042] Next, if the planes are defined, a plane with the vertical axis as the normal direction defined in human anatomy is the transverse plane, a plane including the long axis and with the anterior and posterior directions of the human body as the normal direction is the frontal plane, and a plane including the long axis and with the left and right directions of the human body as the normal direction is the sagittal plane.

[0043] The artificial intervertebral disc 10 basically includes an upper plate 100 whose outer surface contacts the upper vertebra, a lower plate 300 whose outer surface contacts the lower vertebra, and an inserter 200 inserted between the upper plate 100 and the lower plate 300 and configured to rotate the upper plate 100 by a set angle with respect to the lower plate 300 so as to be inserted between two adjacent vertebrae.

[0044] The upper plate 100, the inserter 200, and the lower plate 300 can use materials harmless to the human body. Since the upper plate 100 and the lower plate 300 must be in contact with and fixed to the vertebral body, a polymer material such as PEEK (Poly-Ether-Ether-Ketone), or a metal material such as titanium or a titanium alloy is desirable. In particular, titanium or a titanium alloy is desirable because it has the property of providing excellent osseointegration. In particular, surface roughness can be increased by processes such as sanding, vapor deposition, and coating to have a rough surface so as to be advantageous for osteogenesis, osteoconduction, and osteoinduction at the contact surface with the vertebral body, or it can also be formed to include a porous structure by 3D printing.

[0045] Since the inserter 200 slides while contacting the upper plate 100 and the lower plate 300, a polymer material such as UHMWPE (Ultra High Molecular Weight Polyethylene) with excellent abrasion resistance or a metal material such as a cobalt-chromium (Co-Cr) alloy can be used.

[0046] As shown in FIGS. 9 and 10, since the artificial intervertebral disc 10 is inserted from the side of the patient, it must be adapted to the width along the front-rear axis of the vertebra 20, which is narrower than the length along the left-right axis of the vertebra 20. Also, since the surgery is performed in the flank direction, a minimally invasive surgery (MIS) with a long and narrow surgical path is carried out. Therefore, the artificial intervertebral disc 10 has a substantially rectangular shape that is long in the transverse axis direction and narrow in the front-rear axis direction.

[0047] Therefore, on the upper plate 100 and the lower plate 300, upper blade portions 101 and lower blade portions 301 that extend along the horizontal axis are formed with the inserter 200 inserted therein. That is, the upper plate 100 and the lower plate 300 extend long outside the width length in the horizontal axis direction of the inserter 200, and the upper plate 100 and the lower plate 300 generally have a substantially rectangular shape that is long along the horizontal axis and short along the front-rear axis.

[0048] As described below, in the artificial intervertebral disc 10, the upper plate 100 and the lower plate 300 are bent left and right on the coronal plane with respect to the inserter 200 according to the shape of the inserter 200. At this time, if the inserter 200 has the same length as the upper plate 100 or the lower plate 300, the momentum of the upper plate 100 and the lower plate 300 is restricted by the thickness of the inserter 200 during such left and right bending. Therefore, by forming the upper blade portions 101 and the lower blade portions 301 and relatively shortening the length in the horizontal axis direction of the inserter 200, there is an advantage of increasing the magnitude of the left and right bending of the artificial intervertebral disc 10.

[0049] As shown in FIGS. 3 and 4, the upper plate 100 is composed of a substantially hexahedron including a front upper front wall portion 110, a rear upper rear wall portion 112, an upper installer direction wall portion 106 in the installer direction, an upper insertion direction wall portion 108 in the insertion direction, an outer surface 102 of the upper plate that contacts the vertebra, and an inner surface 104 of the upper plate that is in the direction opposite to the outer surface 102 of the upper plate.

[0050] Similarly, the lower plate 300 is composed of a substantially hexahedron including a front lower front direction wall portion 310, a rear lower rear direction wall portion 312, a lower installer direction wall portion 306 in the installer direction, a lower insertion direction wall portion 308 in the insertion direction, an outer surface 302 of the lower plate that contacts the vertebra, and an inner surface 304 of the lower plate that is in the direction opposite to the outer surface 302 of the lower plate.

[0051] In the lumbar vertebrae of the human body, the lordosis angle of the intervertebral disc increases from the intervertebral disc closer to the thoracic vertebrae to the intervertebral disc closer to the sacrum.

[0052] In the artificial intervertebral disc 10, the shapes of the upper plate 100 and the lower plate 300 are formed such that the thickness in the front is larger than the thickness in the rear so as to correspond to the lordosis angle of the intervertebral disc. Therefore, as shown in FIG. 2, the outer surface 102 of the upper plate of the upper plate 100 and the outer surface 302 of the lower plate of the lower plate 300 can be formed to be inclined with respect to each other.

[0053] Even in that case, the inner surface 104 of the upper plate of the upper plate 100 and the inner surface 304 of the lower plate of the lower plate 300 remain parallel to each other.

[0054] As a result, the artificial intervertebral disc 10 can have not only a lordosis angle of 0°, but also various angles, and can impart the lordosis angle that the intervertebral disc to be operated on in the patient must have, and can maintain the curved shape of the entire lumbar vertebrae.

[0055] The artificial intervertebral disc 10 is inserted between the vertebral bodies from the side of the patient as shown in FIGS. 9 and 10. At the time of such insertion, it is driven in with a strong impact. In the artificial intervertebral disc 10, the contact movement between the inserter 200 and the upper plate 100 and the contact movement between the inserter 200 and the lower plate 300 must be made with the upper plate 100 and the lower plate 300 fixed to the vertebral body 20. Therefore, the upper plate 100 and the lower plate 300 need to be strongly fixed to the vertebral body 20.

[0056] Therefore, an upper keel portion 114 and a lower keel portion 314 can be respectively formed along the horizontal axis on the outer surface 102 of the upper plate of the upper plate 100 and the outer surface 302 of the lower plate of the lower plate 300. As a result, when the artificial intervertebral disc 10 is inserted into the vertebral body 20, the upper keel portion 114 and the lower keel portion 314 will be in close contact with the vertebral body while forcibly forming grooves on the surface of the vertebral body. Therefore, not only does the surface area between the vertebral body and the upper plate 100 and the lower plate 300 increase, but when a load is transmitted from the vertebral body to the upper plate 100 and the lower plate 300, slippage can be prevented.

[0057] Also, as shown in FIGS. 3 and 4, a plurality of upper protrusion portions 116 and lower protrusion portions 316 can be formed on the outer surface 102 of the upper plate of the upper plate 100 and the outer surface 302 of the lower plate of the lower plate 300.

[0058] The upper protrusion portions 116 and the lower protrusion portions 316 have a quadrangular pyramid shape having a quadrangular cross-section composed of four line segments respectively perpendicular to the horizontal axis and the front-rear axis. As a result, the upper protrusion portions 116 and the lower protrusion portions 316 can support loads in both the direction along the horizontal axis and the direction along the front-rear axis, enabling the artificial intervertebral disc 10 to be supported in various directions.

[0059] Next, the inserter 200 will be described.

[0060] In the human body, the intervertebral disc serves as a ligament connecting the vertebrae, a center point of spinal movement, and a role of alleviating spinal shock. In particular, the movement of the spine by the intervertebral disc is of three types: flexion-extension motion, lateral bending, and axial rotation.

[0061] First, flexion and extension in the anterior-posterior direction is a movement performed in the sagittal plane, which is a movement of flexing and extending the body in the anterior-posterior direction. Lateral bending is a movement performed in the coronal plane, which is a movement of tilting the body to the left and right. Axial rotation is a movement called "Twist", which is a movement of twisting and rotating the torso while maintaining a standing upright state.

[0062] The main feature of the inserter 200 is to classify and distribute the above three types of movements. That is, the upper dome portion 202 disposed on the upper side of the inserter 200 is responsible for flexion and extension in the anterior-posterior direction and lateral bending, and the first axial rotation portion disposed on the lower side of the inserter 200 is formed to be responsible for axial rotation. The upper dome portion 202 is in sliding contact with the upper concave groove 120 formed in the upper plate 100, and the first axial rotation portion is in sliding contact with the second axial rotation portion formed in the lower plate 300.

[0063] For this purpose, an upper dome portion 202 is formed on the upper part of the inserter 200, and a first axial rotation portion is formed on the lower part.

[0064] As shown in FIGS. 5 to 7, the upper dome portion 202 has an elliptical hemispherical shape in which the major axis is arranged on the horizontal axis and the minor axis is arranged on the anterior-posterior axis.

[0065] First, referring to FIG. 5, the upper dome portion 202 is formed to form a curved surface in the anterior-posterior direction along the anterior-posterior axis. Also, referring to FIG. 6, the upper dome portion 202 is formed to form a curved surface to the left and right along the horizontal axis.

[0066] Therefore, by combining the two curved surfaces with each other, as shown in FIG. 7, the upper dome portion 202 has an elliptical hemispherical shape.

[0067] Then, as shown in FIG. 3, an upper concave groove 120 is formed in the upper plate 100 so as to correspond to the upper dome portion 202 and slidably contacts it. That is, the upper concave groove 120 also has a curved surface corresponding to the curved surface formed by the upper dome portion 202 along the front-rear axis in the front-rear direction and a curved surface corresponding to the curved surface formed by the upper dome portion 202 along the horizontal axis in the left-right direction at the same time. In particular, the maximum depth of the upper concave groove 120 is formed to be smaller than the maximum height of the upper dome portion 202, and the upper concave groove 120 can be contacted only with a part of the upper dome portion 202.

[0068] An inserter body 204 is formed around the lower side of the upper dome portion 202. The inserter body 204 spreads widely like a flange and is formed in a substantially square or rectangular shape in the embodiment of the present invention, but may also be formed in an elliptical shape.

[0069] The inserter lower surface 210 of the inserter body 204 is formed flat and slidably contacts the inner surface 304 of the lower plate 300 of the lower plate. Since the inner surface 304 of the lower plate is in sliding contact, the load applied to the upper plate 100 can be stably transmitted to the lower plate 300 through the inserter 200.

[0070] Also, the inserter lower surface 210 of the inserter body 204 is formed in a flat state such that the thickness becomes thinner as the inserter upper surface 206 goes from the upper dome portion 202 to the end of the inserter body 204. Referring to the insert body 204 in FIGS. 5 and 6, it can be confirmed that the thickness of the inserter upper surface 206 gradually becomes thinner both along the horizontal axis and along the front-rear axis.

[0071] An upper stopper 118 is formed around the upper concave groove 120. The upper stopper 118 projects from the inner surface 104 of the upper plate.

[0072] When the upper stopper 118 contacts the upper surface 206 of the inserter body 204 of the inserter, the angular momentum of the upper plate 100 with respect to the lower plate 300 is restricted.

[0073] In particular, by forming the upper surface 206 of the inserter so that the thickness becomes thinner as it goes from the upper dome portion 202 to the end of the inserter body 204, the angular momentum of the upper plate 100 with respect to the lower plate 300 can be increased. That is, compared with the case where the upper surface 206 of the inserter has a constant thickness, as the thickness becomes thinner toward the end of the inserter body 204, when the upper stopper 118 contacts the upper surface 206 of the inserter, the inclination angle formed between the upper plate 100 and the lower plate 300 becomes even larger.

[0074] According to an embodiment of the present invention, as illustrated in FIG. 4, the first axis rotation portion disposed below the inserter 200 is a lower outer protrusion 208 formed on the lower surface 210 of the inserter body 204 of the inserter, and the second axis rotation portion is a lower outer groove 320 formed in the lower plate 300, and the lower outer groove 320 has an arc shape.

[0075] The lower outer protrusions 208 are symmetrically arranged with respect to the rotation center along the long axis line of the inserter 200. When there are three or more lower outer protrusions 208, they can be arranged at a certain angle with respect to the rotation center along the long axis line.

[0076] In an embodiment of the present invention, the lower outer protrusion 208 is formed in a substantially hemispherical shape, the lower outer groove 320 is formed in an arc shape so that the lower outer protrusion 208 moves within a certain angular range, and in particular, the end of the lower outer groove 320 has a shape on which the lower outer protrusion 208 can be placed.

[0077] As still another example of the first axis rotation portion, an arc-shaped groove or hole may be formed in the inserter body 204, and a protrusion may be formed on the inner surface 304 of the lower plate of the lower plate 300.

[0078] Further, a lower central protrusion 212 is formed at the rotation center along the major axis line of the lower surface 210 of the inserter 200, and a lower central groove 318 corresponding to the lower central protrusion 212 may be formed in the lower plate 300. Conversely, a groove may be formed at the rotation center along the major axis line of the lower surface 210 of the inserter 200, and a protrusion corresponding thereto may be formed in the lower plate 300.

[0079] By the lower central protrusion 212 and the lower central groove 318 being coupled to each other, not only is the inserter 200 stably rotated with respect to the lower plate 300, but there is also an advantage that stable support can be provided for a load applied to the inserter in the transverse axis or the longitudinal axis, or for a load applied in an arbitrary direction on the cross-section.

[0080] The structure of the artificial intervertebral disc 10 according to the present invention is as described above. Next, the movement of the artificial intervertebral disc 10 will be described in detail.

[0081] The artificial intervertebral disc 10 can perform left - right bending (Lateral bending) and flexion - extension motion between the upper plate 100 and the lower plate 300 when the upper dome portion 202 of the inserter 200 and the upper concave groove 120 of the upper plate 100 come into contact and move.

[0082] That is, as shown in FIG. 7, with the upper concave groove 120 in contact with the upper dome portion 202, while the upper blade portion 101 of the upper plate 100 approaches the lower blade portion 301 of the lower plate 300 in the installer direction, or while moving in the insertion direction with the upper concave groove 120 in contact with the upper dome portion 202, and the upper blade portion 101 of the upper plate 100 approaching the lower blade portion 301 of the lower plate 300 in the installer direction, the upper plate 100 performs left - right bending (Lateral bending) on the frontal plane with respect to the lower plate.

[0083] Also, with the upper concave groove 120 in contact with the upper dome portion 202, if the upper front wall portion 110 of the upper plate 100 approaches forwardly the lower front surface direction wall portion 310 of the lower plate 300, or if, while the upper concave groove 120 is in contact with the upper dome portion 202 and moving rearwardly, the upper rear wall portion 112 of the upper plate 100 approaches rearwardly the lower rear surface direction wall portion 312 of the lower plate 300, then the upper plate 100 makes a flexion-extension motion in the sagittal plane with respect to the lower plate.

[0084] At this time, while the upper stopper 118 around the upper concave groove 120 contacts the inserter upper surface 206 of the inserter body 204, the momentum of lateral bending and flexion-extension motion is restricted.

[0085] Also, with the lower central protrusion 212 of the inserter 200 inserted into the lower central groove 318 of the lower plate 300 as shown in FIG. 8, by moving the lower outer protrusion 208 of the inserter 200 along the lower outer groove 320 of the lower plate 300, the upper plate 100 can make an axial rotation in the transverse plane with respect to the lower plate 300.

[0086] At this time, while the lower outer protrusion 208 contacts both ends of the lower outer groove 320, the momentum of the axial rotation is restricted.

[0087] If such flexion-extension, lateral bending, and axial rotation are made in a composite manner with each other, the artificial intervertebral disc 10 can move in the same way as the motion of the intervertebral disc of the human body.

[0088] According to the artificial intervertebral disc 10 of the present invention, artificial disc replacement (ADR) that can be inserted through a lateral approach becomes possible, and since the surgery is performed by inserting laterally, the anterior longitudinal ligament and the posterior longitudinal ligament that stabilize the spine during the surgery are preserved. As a result, the force transmitted to the posterior joints can be reduced, so that the spine can be held more stably.

[0089] In addition, the anterior longitudinal ligament is a ligament that plays the most important role in preventing hyperflexion of the spine and maintaining the stability of the intervertebral joints. If the anterior longitudinal ligament is cut, the problem of anterior insertion of the artificial intervertebral disc, in which the spine rotates beyond its original range of rotation due to the absence of the anterior longitudinal ligament and places a burden on the posterior joints, can be solved.

[0090] In addition, according to the artificial intervertebral disc 10, since motion control is possible while both the anterior longitudinal ligament and the posterior longitudinal ligament are preserved, the burden on the posterior joints is reduced, and the motion is controlled with the help of the anterior longitudinal ligament and the posterior longitudinal ligament, so that the optimization of the motion state can be achieved.

[0091] As described above, the present invention has been described with reference to the preferred embodiments of the present invention. However, those skilled in the art will understand that the present invention can be variously modified and changed within the scope not departing from the spirit and scope of the present invention described in the claims.

Industrial Applicability

[0092] In the case of an artificial intervertebral disc inserted anteriorly, cooperation with a thoracic surgeon or a vascular surgeon is required to ensure laparotomy and the surgical approach. However, in the case of a spinal implant inserted laterally, since the organs do not interfere from the skin to the spine, there is an advantage that the surgery can be performed only by an orthopedic surgeon or a neurosurgeon.

[0093] Therefore, the artificial intervertebral disc according to the present invention can overcome the problems and disadvantages of the conventional anterior insertion type artificial intervertebral disc, and can keep the patient's mobility intact while being inserted laterally. Thus, it is expected that not only the existing artificial intervertebral discs but also the laterally inserted fixation cages can be replaced by it.

Claims

1. In an artificial intervertebral disc inserted between two adjacent vertebrae, an upper plate contacting the upper vertebra, a lower plate contacting the lower vertebra, and an inserter inserted between the upper plate and the lower plate and configured to rotate the upper plate relative to the lower plate by a set angle, wherein the upper plate and the lower plate are formed with an upper fin portion and a lower fin portion extending along a horizontal axis with the inserter inserted therein, characterized in that it is an artificial lumbar intervertebral disc.

2. The artificial lumbar intervertebral disc according to claim 1, wherein the upper plate and the lower plate have a greater thickness at the front than at the rear.

3. The artificial lumbar intervertebral disc according to claim 1 or 2, wherein an upper keel portion and a lower keel portion are formed along the horizontal axis on the outer surface of the upper plate of the upper plate and the outer surface of the lower plate of the lower plate, respectively.

4. The artificial lumbar intervertebral disc according to claim 1 or 2, wherein a plurality of upper protrusions and lower protrusions are formed on the outer surface of the upper plate of the upper plate and the outer surface of the lower plate of the lower plate, respectively.

5. The artificial lumbar intervertebral disc according to claim 4, wherein the upper protrusion and the lower protrusion each have a quadrangular pyramid shape having a quadrangular cross-section composed of four line segments perpendicular to the horizontal axis and the front-rear axis, respectively.

6. The inserter has an upper dome portion formed at the upper part and a first-axis rotation portion formed at the lower part, an upper concave groove corresponding to the upper dome portion and in sliding contact with the upper dome portion is formed on the upper plate, and a second-axis rotation portion contacting the first-axis rotation portion is formed on the lower plate, characterized in that it is an artificial lumbar intervertebral disc according to claim 1 or 2.

7. The upper dome portion is formed in an elliptical hemispherical shape with a major axis arranged on the horizontal axis and a minor axis arranged on the front-rear axis, and by the upper dome portion and the upper concave groove contacting and moving, the upper plate performs left-right bending and flexion-extension motion relative to the lower plate, characterized in that it is an artificial lumbar intervertebral disc according to claim 6.

8. The artificial lumbar intervertebral disc according to claim 7, wherein the maximum depth of the upper concave groove is formed smaller than the maximum height of the upper dome portion.

9. An upper stopper is formed around the upper concave groove, and the upper stopper contacts the upper surface of the inserter of the inserter body formed around the upper dome portion, whereby the angular momentum of the upper plate is restricted. The artificial lumbar intervertebral disc according to claim 6, characterized in that.

10. The lower surface of the inserter of the inserter body is formed flat, and the upper surface of the inserter is formed such that the thickness decreases from the upper dome portion toward the end of the inserter body. The artificial lumbar intervertebral disc according to claim 9, characterized in that.

11. The first-axis rotation portion is a lower outer protrusion formed on the lower surface of the inserter, and the second-axis rotation portion is a lower outer groove formed on the lower plate. The lower outer groove is formed in an arc shape. The artificial lumbar intervertebral disc according to claim 6, characterized in that.

12. A lower central protrusion is formed at the center of the lower surface of the inserter, and a lower central groove corresponding to the lower central protrusion is formed in the lower plate. The artificial lumbar intervertebral disc according to claim 11, characterized in that.

Images