WO2025143719A1 - Front insertion type artificial disc - Google Patents

Abstract

The present invention provides a front insertion type artificial disc having a simple structure and capable of implementing the movement of a human body, the front insertion type artificial disc, which is inserted between two adjacent vertebrae, capable of implementing the movement of the human body with a simple structure, comprising: an upper plate having an upper surface coming into contact with the upper vertebra; a lower plate having an upper surface coming into contact with the lower vertebra; and an inserter which is inserted between the upper plate and the lower plate, wherein the upper spherical surfaces of the upper plate and the inserter are in surface-contact with each other to form a spherical pair, and the inserter carries out rotational movement relative to the lower plate by using a major axis as a rotation center axis.

Description

Anterior implantable artificial disc

The present invention relates to an anteriorly inserted artificial disc, and more particularly, to an artificial disc that can be inserted from an anterior approach into a vertebral body.

The vertebral body is made up of 32 to 35 vertebrae that make up the torso and the intervertebral disks between the vertebrae, and it is the central part of our body that connects the skull at the top and the pelvis at the bottom.

The spine is made up of seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, five sacral vertebrae, and three to five coccyx vertebrae from top to bottom. In adults, five sacral vertebrae fuse to form one sacrum, and three to five coccyx fuse to form one coccyx.

Between the vertebrae, there is a cartilaginous substance called a disc. This cartilaginous substance is a soft and squishy fibrocartilage that forms a cartilaginous joint to help the spine move flexibly, acts like a ligament that fixes the spine, and absorbs and reduces the shock applied to the vertebrae. The intervertebral disc is composed of a fibrous disc with a fibrous outer part and a nucleus pulposus with a gel-like substance inside, which maintains strength and helps disperse stress. In other words, the intervertebral disc absorbs the body's load and shock between each vertebra except for some of the cervical vertebrae, and acts as a buffer that disperses the shock like a spring. In addition, it holds the vertebrae together so that they do not come off, separates the two vertebrae so that the spinal nerves are not compressed, maintains the range of the spinal joint space, and plays a role in smoothing the movement of each vertebra.

As these intervertebral discs absorb and transmit vertical loads and shocks, they can cause various diseases such as spinal stenosis, osteophyte formation, disc herniation, and nerve root compression.

One of the treatment methods for serious spinal diseases that has been around for a long time is spinal fusion. This spinal fusion is a surgical procedure that removes the intervertebral disc and inserts a cage to replace it, thereby fusing the adjacent vertebrae together.

When performed on the lumbar spine, these spinal fusions can be classified into posterior lumbar interbody fusion (PLIF), transformational lumbar interbody fusion (TLIF), lateral lumbar interbody fusion (LLIF), oblique lumbar interbody fusion (OLIF), and anterior lumbar interbody fusion (ALIF) depending on the insertion direction of the cage.

Posterior interbody fusion (PLIF) is a method in which an incision is made along the midline of the spine, the vertebral body is opened to expose the entire vertebral body, a portion of the posterior part of the vertebra is removed, the disc is removed, and a PLIF cage is inserted.

Posterior interbody fusion (PLIF) is the oldest spinal fusion technique and is an essential method when performing two- or three-joint fusions. However, there are disadvantages such as a high possibility of adhesion to nerves, ligaments, and muscles due to the surgical procedure, a long healing time due to the large incision area, and, depending on the person, significant aftereffects.

The PLIF cage consists of a pair of smaller cages placed on each side, and is the smallest cage used in all spinal fusion surgeries.

Transverse foraminal interbody fusion (TLIF) is a surgical method in which a small incision is made along both sides of the spinal muscles, the vertebral body is minimally exposed, the spinal joint area is removed in the direction of the neural foramen, and the TLIF cage is inserted into the disc. This surgical technique has the advantages of less bleeding and shorter surgical time, so it is suitable for single-joint surgeries, but PLIF surgery should be performed when multiple areas require surgery. The TLIF cage is mostly shaped like an arc, so 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 its supporting area is smaller than that of the LLIF or ALIF cage, which will be mentioned later.

Anterior interbody fusion (ALIF) has many advantages, such as quick recovery from surgery and no need to worry about adhesions, but it has the disadvantage of requiring highly skilled techniques because it is performed by making an anterior (ventral) incision, removing the internal organs, and approaching the spine. The ALIF cage has the advantage of having the largest support surface area among all spinal fusion cages.

Lateral lumbar fusion (LLIF) was developed to overcome the shortcomings of ALIF, PLIF, and TLIF. Lateral lumbar fusion is performed through a side incision, so it can widen the space between the vertebrae and the stenotic area more than the existing back incision surgeries, and has the advantage of causing little damage to the surrounding tissues. However, since the psoas muscle and peritoneum are located around the surgical path, there are problems such as thigh muscle paralysis if there is a mistake during the surgery. The LLIF cage is smaller than the ALIF cage, but smaller than the PLIF or TLIF cages.

Compared to this lateral lumbar fusion, the oblique lumbar interbody fusion (OLIF or ATP fusion) is a safer and more effective surgical method. The oblique lumbar interbody fusion is performed in the direction described from the side, and has the advantage of being possible between the 4th lumbar (L4) and 5th lumbar (L5) vertebrae, which are difficult to operate with DLIF, due to the psoas muscle and peritoneum. In addition, the possibility of damaging the nerves, which is a problem in lateral lumbar fusion, is significantly lower.

However, since the spinal fusion described above makes the upper and lower vertebrae into one, from the patient's perspective, one of the corresponding discs is missing, and the patient loses the amount of movement that the disc was responsible for.

To solve this problem of loss of mobility, the artificial disc was developed. The surgical method for the artificial disc is to first remove the damaged intervertebral disc, then create a space between two adjacent vertebrae, and then insert the artificial disc into this space. The artificial disc itself has the advantage of maintaining mobility even after surgery because the upper and lower plates can move within a certain range of angles.

In conventional artificial disc replacement surgery, the posterior arch, which consists of a pair of pedicles and the superior and inferior articular processes extending posteriorly from the pedicles, the lamina propria, and the supraspinous process, is located on the back, so the surgery was performed from the anterior approach after opening the abdomen, resecting the peritoneum, and lifting and moving the organs.

To explain in more detail, first, the patient is laid face up, and the abdomen on the front of the body is incised, and the surgical path is secured to the spine, avoiding the organs. Then, a part of the anterior longitudinal ligament is incised on the front side of the spine. When the anterior longitudinal ligament is incised, the disc between the vertebrae is exposed. This disc is removed using a surgical instrument, and an artificial disc is inserted in its place.

Artificial discs according to conventional technology usually include an upper plate and a lower plate that contact the vertebral body, and an inserter that is inserted between the upper plate and the lower plate. However, conventional technologies disclosed so far have a disadvantage in that they cannot accurately implement the spinal movement of the human body because they simply rely on spherical contact between the upper plate and the inserter.

The present invention is intended to solve the above problems, and aims to provide an anteriorly inserted artificial disc that can be inserted from the anterior approach of a vertebral body, and that can implement human body movement while having a simple structure.

In order to achieve the above object, the present invention provides an anteriorly inserted artificial disc, which comprises: an upper plate having an upper surface in contact with an upper vertebra; a lower plate having an upper surface in contact with a lower vertebra; and an inserter inserted between the upper plate and the lower plate, wherein upper spherical surfaces of the upper plate and the inserter are in surface contact with each other to form a spherical surface, and the inserter rotates with respect to the lower plate about its major axis as a center of rotation.

The inserter is characterized in that the upper plate slides within a predetermined angular range with respect to the longitudinal axis, and the inserter slides within a predetermined angular range with respect to a plane normal to the longitudinal axis with respect to the lower plate.

In addition, the upper spherical surface is formed with an upper limiting groove, and an upper limiting protrusion is formed on an upper concave surface formed on the lower portion of the upper plate and in contact with the upper spherical surface, the range of motion of which is limited by the upper limiting groove.

In addition, the lower plate is characterized in that a lower groove is formed in the lower portion of the inserter into which a lower swivel is inserted, a lower limiting projection is formed on one of the lower swivel and the lower groove, and a lower limiting groove is formed on the other of the lower swivel and the lower groove to limit the range of motion of the lower limiting projection.

In addition, it is characterized in that a swivel neck portion is protrudingly formed on the side of the lower swivel, a swivel fitting portion is formed on the lower portion of the swivel neck portion, a lower fixing jaw corresponding to the swivel neck portion is formed on the side of the lower groove, and a lower fitting portion into which the swivel fitting portion is inserted is formed under the lower portion of the lower fixing jaw.

In addition, it is characterized in that a lower free space is formed concavely around the lower limit protrusion.

In addition, the cross-sectional area of the lower groove is larger than the cross-sectional area of the lower swivel, so that the lower swivel is capable of moving within the lower groove.

According to an embodiment of the present invention configured as described above, it can be applied to the cervical or lumbar vertebrae because it is inserted into the front of the spine.

In addition, an anteriorly inserted artificial disc can be provided that has a simple structure but can implement human body movement.

FIG. 1 is a perspective view of an artificial disc according to an embodiment of the present invention.

Figure 2 is a perspective view of the artificial disc of Figure 1 seen from above after being disassembled.

Figure 3 is a perspective view of the artificial disc of Figure 1 seen from below after being disassembled.

Figure 4 is a drawing showing the artificial disc of Figure 1 being inserted into the vertebral body.

Figure 5 is a drawing showing the artificial disc of Figure 1 inserted into the vertebral body.

Hereinafter, the present invention will be described with reference to the attached drawings, which illustrate preferred embodiments of the present invention. When adding reference symbols to components in each of the drawings below, the same components will be given the same symbols as much as possible even if they are shown in different drawings, and detailed descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

FIG. 1 illustrates an artificial disc (100) according to an embodiment of the present invention. First, directions are defined. The patient's abdominal direction is called the Anterior Direction, and the patient's back direction is called the Posterior Direction. Therefore, the Anterior Direction and the Posterior Direction are opposite to each other. In addition, the patient's right side is called the Right Direction, and the patient's left side is called the Left Direction. In addition, the patient's head direction is called the Superior Direction, and the patient's leg direction is called the Inferior Direction.

And, the imaginary straight line defined in the forward and backward directions is called the Anterior to Posterior Axes, and the imaginary straight line defined in the right and left directions is called the Lateral Axis. Also, the imaginary straight line defined in the upper and lower directions is called the Vertical Axis. Therefore, the Anterior to Posterior Axis, the Horizontal Axis, and the Major Axis are perpendicular to each other.

Next, when defining a plane, the transverse plane is defined as a plane that has the major axis as the normal direction according to the definition in human anatomy, the frontal plane is defined as a plane that includes the major axis as the normal direction in the front-back direction of the human body, and the sagittal plane is defined as a plane that includes the major axis as the normal direction in the left-right direction of the human body.

The artificial disc (100) is configured to be inserted between two adjacent vertebrae, and includes an upper plate (102) whose upper surface is in contact with the upper vertebrae, a lower plate (104) whose upper surface is in contact with the lower vertebrae, and an inserter (106) that is inserted between the upper plate (102) and the lower plate (104) to allow the upper plate (102) to rotate at a set angle with respect to the lower plate (104).

With respect to the inserter (106), the upper plate (102) slides within a predetermined angular range relative to the longitudinal axis, and the inserter (106) slides within a predetermined angular range relative to a plane having the longitudinal axis as a normal line relative to the lower plate (104).

The upper plate (102), the inserter (106), and the lower plate (104) may use materials that are harmless to the human body. Since the upper plate (102) and the lower plate (104) must be fixed by contacting 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 preferable. In particular, titanium or a titanium alloy is preferable because it has the characteristic of providing excellent osseointegration. In particular, the surface roughness may be increased by sanding, deposition, coating, etc. 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 may be formed to include a porous structure by 3D printing.

Since the above inserter (106) slides while in contact with the upper plate (102) and the lower plate (104), a polymer material such as UHMWPE (Ultra High Molecular Weight Polyethylene) with excellent wear resistance or a metal material such as a cobalt chromium (Co-Cr) alloy can be used.

Each element of the artificial disc (100) is described in detail with reference to FIGS. 2 and 3.

The inserter body (170) of the inserter (106) above has a cross-section that is approximately square or circular and has a thickness in the direction of the longitudinal axis. An upper spherical surface (172) is formed on the upper portion of the inserter body (170) to form a convex sphere as a part of a sphere. That is, the upper spherical surface (172) is formed to protrude in the head direction with respect to the inserter body (170). In addition, an upper limiting groove (174) is formed on the center of the upper portion of the upper spherical surface (172) to have an approximately circular groove.

In addition, a lower swivel (176) is formed protruding from the lower portion of the inserter body (170). The leg-directed surface of the lower swivel (176) is a plane. That is, the lower swivel (176) is formed protruding in the leg direction with respect to the inserter body (170), and the bottom surface of the lower swivel (176) is parallel to the cross-section.

The cross-sectional area of the lower swivel (176) is formed smaller than the cross-sectional area of the inserter body (170). The cross-sectional shape of the lower swivel (176) is approximately circular. In addition, a lower limiting projection (182) is formed to protrude in the left and right directions of the lower swivel (176).

The lower limiting protrusion (182) and the lower swivel (176) are formed so as not to protrude outward from the side of the inserter body (170). In addition, a lower free space (184) is formed concavely at the portion where the lower limiting protrusion (182) begins to protrude from the lower swivel (176). The lower free space (184) not only provides a space through which a cutter can pass when manufacturing the lower swivel (176) and the lower limiting protrusion (182), but can also be utilized as a space through which foreign substances can escape when the artificial disc (100) is inserted into the human body.

On the side of the lower swivel (176), a swivel neck (180) and a swivel fitting (178) are continuously formed in the leg direction. The swivel neck (180) has a smaller cross-sectional area than the swivel fitting (178).

The upper plate (102) is roughly plate-shaped and has a thickness in the direction of the longitudinal axis. In addition, the cross-section of the upper plate (102) has a rectangular cross-section similar to the cross-sectional shape of a disc in the human body.

The upper plate (102) is composed of approximately a hexahedron of an upper plate front portion (108) in the forward direction, an upper plate rear portion (110) in the backward direction, upper plate side portions (112) in the left and right directions, an upper plate outer surface (114) that comes into contact with the vertebrae, and an upper plate inner surface (116) that is opposite to the upper plate outer surface (114).

The thickness of the upper plate (102) may be formed so that the thickness of the front part (108) of the upper plate and the thickness of the rear part (110) of the upper plate are the same, or the thickness of the front part (108) of the upper plate may be formed so that it is thicker than the thickness of the rear part (110) of the upper plate.

The lordosis angle of the disc in the human spine varies. Accordingly, by changing the thickness of the upper plate (102), the artificial disc (100) can have the lordosis angle of the disc not only 0 degrees but also various angles, thereby providing the lordosis angle that the disc to be surgically treated in the patient should have, thereby maintaining the overall curved shape of the spine.

On the upper plate (102), the inner surface (116) of the upper plate positioned in the leg direction has an upper concave surface (122) formed as a concave spherical surface that can be spherically opposed to the upper spherical surface (172). In addition, an upper limiting protrusion (124) is formed at the center of the upper concave surface (122). The upper limiting protrusion (124) is inserted into the upper limiting groove (174). As a result, the upper plate (102) makes a spherical contact movement with respect to the inserter (106), but since the upper limiting protrusion (124) is inserted into the upper limiting groove (174), the angular range of the spherical contact movement of the upper plate (102) with respect to the inserter (106) is limited.

In the upper plate (102), an upper central protrusion (118) and an upper peripheral protrusion (120) are formed in the forward and backward directions on the outer surface (114) of the upper plate that contacts the vertebral body to enhance the support force with the vertebral body. The upper central protrusion (118) and the upper peripheral protrusion (120) are wedge-shaped, and the direction of the wedge is arranged such that the inclined surface faces the backward direction so that the artificial disc (100) does not come off while inserted into the vertebral body.

And, an upper mechanism groove (126) is formed on the upper plate side (112) so that it can be gripped by an insertion mechanism (not shown). That is, the gripping portion (not shown) of the insertion mechanism can be inserted into the upper mechanism groove (126). And, an upper mechanism guide part (128) is formed in the forward direction of the upper mechanism groove (126). The upper mechanism guide part (128) is formed in a curved shape so that it is easy to detach the insertion mechanism from the artificial disc (100) when the artificial disc (100) is inserted into the vertebral body using the insertion mechanism.

The lower plate (104) is roughly plate-shaped and has a thickness in the longitudinal direction. In addition, the cross-section of the lower plate (104) has a rectangular cross-section similar to the cross-sectional shape of a human body disc.

The above lower plate (104) is composed of approximately a hexahedron of a lower plate front portion (138) in the forward direction, a lower plate rear portion (140) in the backward direction, lower plate side portions (142) in the left and right directions, a lower plate outer surface (144) that comes into contact with the vertebrae, and a lower plate inner surface (146) that is opposite to the lower plate outer surface (144).

The thickness of the lower plate (104) may be formed so that the thickness of the front part (138) of the lower plate and the thickness of the rear part (140) of the lower plate are the same, or the thickness of the front part (138) of the lower plate may be formed so that it is thicker than the thickness of the rear part (140) of the lower plate.

The lordosis angle of the disc in the human spine varies. Accordingly, by changing the thickness of the lower plate (104), the artificial disc (100) can have the lordosis angle of the disc not only 0 degrees but also various angles, thereby providing the lordosis angle that the disc to be operated on in the patient should have, thereby maintaining the overall curved shape of the spine.

A lower groove (152) into which the lower swivel (176) is inserted is formed on the inner surface (146) of the lower plate positioned in the head direction of the lower plate (104).

The bottom surface of the lower groove (152) is flat and makes sliding contact with the bottom surface of the lower swivel (176). In addition, since the cross-sectional area of the lower groove (152) is larger than that of the lower swivel (176), the lower swivel (176) can move within the lower groove (152).

A lower limit groove (158) is formed on the left and right sides of the lower groove (152). The lower limit groove (158) is a space into which the lower limit protrusion (182) is inserted, and has a size that allows the lower limit protrusion (182) to move at a certain angle.

In addition, a lower fitting part (156) and a lower fixing jaw (154) are formed on the side of the lower groove (152). The lower fitting part (156) corresponds to the swivel fitting part (178), and the lower fixing jaw (154) corresponds to the swivel neck part (180).

Accordingly, since the swivel fitting part (178) is inserted into the lower fitting part (156), the swivel neck part (180) is restrained by the lower fixing jaw (154), so the inserter (106) does not come off with respect to the lower plate (104).

In the lower plate (104), on the outer surface (144) of the lower plate that comes into contact with the vertebral body, a lower central protrusion (148) and a lower peripheral protrusion (150) are formed from the front to the back in order to improve the support force with the vertebral body. The lower central protrusion (148) and the lower peripheral protrusion (150) are wedge-shaped, and the direction of the wedge is arranged such that the inclined surface faces the back so that the artificial disc (100) does not come off while inserted into the vertebral body.

And, a lower mechanism groove (160) is formed on the lower plate side (142) so that it can be gripped by an insertion mechanism (not shown). That is, the gripping portion (not shown) of the insertion mechanism can be inserted into the lower mechanism groove (160). And, a lower mechanism guide portion (162) is formed in the forward direction of the lower mechanism groove (160). The lower mechanism guide portion (162) is formed in a curved shape so that it is easy to detach the insertion mechanism from the artificial disc (100) when the artificial disc (100) is inserted into the vertebral body using the insertion mechanism.

The structure of the artificial disc (100) according to the present invention is as described above. Next, the movement of the artificial disc (100) will be described in detail.

As shown in FIGS. 4 and 5, the artificial disc (100) is inserted into the vertebral body (10) toward the posterior direction by opening the front side of the patient. At this time, the upper plate (102) and the lower plate (104) of the artificial disc (100) must be fixed to the vertebral body (10) while the contact movement between the inserter (106) and the upper plate (102) and the contact movement between the inserter (106) and the lower plate (104) must be performed. Therefore, the upper plate (102) and the lower plate (104) need to be strongly fixed to the vertebral body (10).

Accordingly, the upper central protrusion (118) and the upper peripheral protrusion (120), and the lower central protrusion (148) and the lower peripheral protrusion (150) formed on the upper plate outer surface (102) of the upper plate (102) and the lower plate outer surface (302) of the lower plate (104) forcefully form grooves on the surface of the vertebral body (10) when the artificial disc (100) is inserted into the vertebral body (10), thereby coming into close contact with the vertebral body. Accordingly, not only does the surface area between the vertebral body and the upper plate (102) and the lower plate (104) increase, but also slipping is prevented when a load is transmitted from the vertebral body to the upper plate (102) and the lower plate (104).

In the human body, discs serve as ligaments that connect the vertebrae, as the center of motion for the spine, and as shock absorbers for the spine. In particular, the spinal movements caused by discs are three types: flexion-extension motion, lateral bending, and axial rotation.

First, forward and backward flexion is an exercise performed in the sagittal plane, and is an exercise of leaning the body forward or backward. Left and right bending is an exercise performed in the frontal plane, and is an exercise of tilting the body left and right. Axis rotation is a so-called twist exercise, and is an exercise of rotating the torso while maintaining a straight state.

The lower plate (104) and the inserter (106) are capable of rotational movement in a plane, i.e., a cross-section, with the major axis as a normal line. At this time, since the movement of the lower limiting projection (182) of the inserter (106) is limited by the lower limiting groove (158) of the lower plate (104), the inserter (106) is capable of rotational movement only within a certain angular range with respect to the inserter (106). However, since the cross-sectional area of the lower groove (152) of the lower plate (104) is slightly larger than the cross-sectional area of the lower swivel (176), translational movement of the inserter (106) with respect to the lower plate (104) is also possible at the same time.

In addition, the upper plate (102) is capable of spherical contact motion with respect to the inserter (106). That is, since the upper plate (102) forms a spherical contact with the inserter (106), all of the motions of the spine by the disc, such as flexion-extension motion, lateral bending, and axial rotating, are possible.

Since the movement of the human body is a complex combination of forward and backward flexion and extension, left and right bending, and axial rotation, when forward and backward flexion and axial rotation occur simultaneously or when left and right bending and axial rotation occur simultaneously, the spherical contact motion of the upper plate (102) and the inserter (106) cannot implement such a complex motion. In this case, if the upper plate (102) and the inserter (106) are responsible for only forward and backward flexion or left and right bending while the lower plate (104) and the inserter (106) perform axial rotation at the same time, the complex motion can be implemented.

In addition, when the upper plate (102) performs a forward bending motion with respect to the inserter (106), the artificial disc (100) is always subjected to a vertical load in the longitudinal direction, so the inserter (106) is pushed backward in the lower groove (152) of the lower plate (104). Accordingly, the forward bending motion of the upper plate (102) with respect to the inserter (106) can be performed more smoothly.

Conversely, when the upper plate (102) is bent backwards with respect to the inserter (106), the inserter (106) is pushed forwards in the lower groove (152) of the lower plate (104). Accordingly, the backward bending movement of the upper plate (102) with respect to the inserter (106) can be performed more smoothly.

Likewise, when the upper plate (102) bends to the left with respect to the inserter (106), the inserter (106) is pushed to the right in the lower groove (152) of the lower plate (104). Accordingly, the leftward bending movement of the upper plate (102) with respect to the inserter (106) can be performed more smoothly.

In addition, when the upper plate (102) performs a rightward bending motion with respect to the inserter (106), the inserter (106) is pushed to the left in the lower groove (152) of the lower plate (104). Accordingly, the rightward bending motion of the upper plate (102) with respect to the inserter (106) can be performed more smoothly.

As these forward and backward bends, left and right bends, and axial rotations occur in combination, the artificial disc (100) can move in a similar way to the movement of a disc in the human body.

As described above, although the present invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the present invention can be variously modified and changed within the scope and spirit of the present invention as set forth in the claims below.

Therefore, it is expected that the artificial disc according to the present invention can replace existing artificial discs because it overcomes the problems and disadvantages of conventional anteriorly inserted artificial discs and allows patients to maintain their mobility.

<Description of drawing symbols>

10: Vertebra 100: Artificial disc

102: Upper plate 104: Lower plate

106: Inserter 108: Front of upper plate

110: Upper plate rear 112: Upper plate side

114: Upper plate outer surface 116: Upper plate inner surface

118: Upper central protrusion 120: Upper peripheral protrusion

122: Upper concave surface 124: Upper limit projection

126: Upper mechanism home 128: Upper mechanism guide section

138: Lower plate front 140: Lower plate rear

142: Lower plate side 144: Lower plate outer surface

146: Inside of lower plate 148: Lower center projection

150: Lower peripheral projection 152: Lower groove

154: Lower fixing jaw 156: Lower fitting part

158: Lower limit home 160: Lower mechanism home

162: Lower mechanism guide 170: Inserter body

172: Upper sphere 174: Upper limit groove

176: Lower swivel 178: Swivel fitting

180: Swivel neck 182: Lower limit projection

184: Lower margin

Claims (7)

In an artificial disc inserted between two adjacent vertebrae, The upper plate, whose upper surface is in contact with the upper vertebra; A lower plate whose upper surface contacts the lower vertebra; and Including an inserter inserted between the upper plate and the lower plate, The upper spherical surface of the upper plate and the inserter are in surface contact with each other to form a spherical surface. An anteriorly inserted artificial disc, characterized in that the inserter performs a rotational movement with the longitudinal axis as the center of rotation axis with respect to the lower plate. In the first paragraph, An anterior insertable artificial disc, characterized in that the upper plate slides within a predetermined angular range with respect to the longitudinal axis with respect to the inserter, and the inserter slides within a predetermined angular range with respect to a plane having the longitudinal axis as a normal line with respect to the lower plate. In the second paragraph, An anterior insertable artificial disc characterized in that an upper limiting groove is formed on the upper spherical surface, and an upper limiting protrusion is formed on an upper concave surface formed on the lower portion of the upper plate and in contact with the upper spherical surface, the range of motion of which is limited by the upper limiting groove. In the third paragraph, The lower plate has a lower groove formed into which a lower swivel formed at the lower portion of the inserter is inserted. An anteriorly inserted artificial disc characterized in that a lower limiting projection is formed on one of the lower swivel and the lower groove, and a lower limiting groove that limits the range of motion of the lower limiting projection is formed on the other of the lower swivel and the lower groove. In paragraph 4, An anterior insertion type artificial disc characterized in that a swivel neck portion is protrudedly formed on the side of the lower swivel, a swivel fitting portion is formed on the lower portion of the swivel neck portion, a lower fixing jaw corresponding to the swivel neck portion is formed on the side of the lower groove, and a lower fitting portion into which the swivel fitting portion is inserted is formed under the lower portion of the lower fixing jaw. In paragraph 4, An anteriorly inserted artificial disc characterized in that a lower free space is formed concavely around the lower limiting protrusion. In paragraph 4, An anteriorly inserted artificial disc, characterized in that the cross-sectional area of the lower groove is larger than the cross-sectional area of the lower swivel, so that the lower swivel can move within the lower groove.

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