JPH11137585A - Artificial vertebral disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To address disturbance in daily life and relapsing probability due to the absence of mobility and motility in the spinal fusion using a self-bone and a spacer. SOLUTION: A mobile protrusion 11 having the tip thereof with a circular arc-shaped cross section is integrally formed on an opposed internal surface at a base body part of a first link body 2 while a mobile bearing part 13 is formed sunk in an opposed internal surface at a base body part of a second link body 3. The mobile bearing part 13 is constituted of a bearing surface 15 which the tip of the mobile protrusion 11 contacts and a bank body 14 formed protruding on the perimeter of the bearing surface 15. Upper and lower clearances are provided between two of the first and second link bodies 2 and 3 while a horizontal clearance is provided between the outer circumference of the mobile protrusion 11 and the inner circumference of the bank body 14. Thus, the first and second link bodies 2 and 3 of an artificial vertebral disk mounted on an affected has mobility ... rotation, sliding or the like ... to imparts motility to a spinal column.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for treating herniated discs and other diseases, damage to the spine (cervical vertebra, lumbar vertebra, etc.) due to accidents, etc., and connects vertically adjacent healthy vertebral bodies. The present invention relates to an artificial disc that is inserted into a resected portion of a disease after the disc is excised.

[0002]

2. Description of the Related Art Conventionally, the vertebral bodies of vertebrae connected vertically are connected by an intervertebral disc, and the intervertebral disc supports the motion of the spine. And with unnatural exercise, aging, degeneration,
When a herniated disc or other diseases or injuries develop and the symptoms are severe, surgical treatment has been performed in which the intervertebral disc is excised by open surgery and an autologous bone or artificial disc is inserted into the diseased part.

[0003] In the above-mentioned spinal fixation of an artificial disc formed into a substantially disc shape or a rectangular parallelepiped shape as an autogenous bone or a spacer, the autogenous bone and the like only have a function of supporting a load, and the spine originally has no function. Did not have a motor support effect. Therefore, it cannot follow the movement of the human body, hinders daily life, or exerts an unreasonable external force, or imposes an excessive load on the discs above and below the treatment unit in daily life. There was a disadvantage that the upper and lower peripheral portions were easily damaged again.

[0004]

SUMMARY OF THE INVENTION The present invention provides an artificial disc for imparting motility to an artificial disc inserted and implanted between vertically adjacent vertebral bodies.

[0005]

According to the present invention, spinal fusion using an autogenous bone or a spacer based on the above-mentioned prior art does not have mobility and motility, and impairs daily life and relapses. In view of the above problem, a movable projection having an arc-shaped cross section is integrally formed on the opposing inner surface of the base portion of the first coupling body, and a movable receiving portion is depressed and formed on the opposing inner surface of the base portion of the second coupling body. The movable receiving portion is constituted by a receiving surface with which the tip of the movable projection comes into contact, and a bank formed to protrude around the receiving surface, and a vertical gap is provided between the two first and second coupling bodies. By providing a horizontal gap between the outer periphery of the movable projection and the inner periphery of the embankment, the first and second joints of the artificial disc attached to the diseased part have movability such as rotation and sliding. Thus, the above problem is solved by imparting mobility to the spine.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The artificial disc 1 of the present invention comprises a pair of upper and lower first and second connected bodies 2 and 3, as shown in FIG. 1, for example. As shown in FIG. 4, when the artificial disc 1 is attached to the diseased part, the opposing inner surfaces 4, 5 are connected with their contact surfaces being movable (see FIGS. 5, 6). First,
Upper and lower outer surfaces 6, 7 of the second connectors 2, 3 are connected in surface contact with healthy upper and lower vertebral bodies M1, M2 of the resected disc. In the drawing, the first connector 2 is disposed on the upper side and the second connector 3 is disposed on the lower side. However, the first connector 2 may be turned upside down.

[0007] Then, as shown in FIGS.
In the connecting body 2, a movable projection 11 having a hemispherical shape and a lower end portion having an arc-shaped cross section is integrally formed on the lower surface side of the flat base member 10 so as to protrude downward.

On the other hand, in the lower second connector 3, the movable projection 11 of the first connector 2 is
The movable receiving portion 13 which is fitted in a movable state is formed to be depressed. More specifically, the embankment body
The protrusion 14 is integrally formed, a receiving surface 15 having a lower circular arc surface 17 is formed on the inner bottom surface of the embankment 14, and the concave portion of the upper surface opening formed by the embankment 14 and the receiving surface 15 is movable. The receiving unit 13 is formed.

Also, the movable projection provided on the first connecting member 2 described above.
In a state where the movable receiving portion 13 provided on the second connector 3 is fitted and connected, the lower surface of the base 10 in the first connector 2 and the second
An upper and lower gap T1 having a predetermined interval is provided between the upper ends of the bank bodies 14 in the connecting body 3, and between the outer periphery of the movable protrusion 11 in the first connecting body 2 and the inner circumference of the bank body 14 in the second connecting body 3. Has a horizontal gap T2 at a predetermined interval.

Further, as shown in FIGS.
A plurality of triangular pyramid-shaped fixing projections 20, 20a... Are integrally formed on the outer surfaces 6, 7 of the connecting bodies 2, 3. In addition, fixed projection
The shape of triangular pyramid is shown in the figure of 20, 20a ...
The shape such as a conical shape, a square shape, a triangular cross-section and a long ridge line can be appropriately selected. And, as shown in FIG.
The first and second connectors 2, 3 of the artificial disc 1 inserted into the diseased part in a state of surface contact with the healthy vertebral bodies M1, M2 at the time of surgery are:
It is pressed by the upper and lower vertebral bodies M1, M2, and the fixing projections 20, 20a
... and the vertebral bodies M1 and M2 are in a firmly connected state as time elapses after the operation. In addition, although not shown, in order to insert the artificial disc 1 into a diseased part at the time of surgery or to improve the convenience of handling a surgical jig, a grasped portion, an incision is made outside the artificial disc 1 or the like. A part or the like may be formed.

Next, the operation of the artificial disc of the first embodiment having such a configuration will be described. The artificial disc 1 inserted into the diseased part depends on the inserted part, such as the lumbar vertebra or cervical vertebra, but as shown in FIG. First connecting body 2 to connecting body 3
Is in an inclined state. In the illustrated example, the lower vertebral body M2 (the second connector 3) and the upper vertebral body M
The insertion inclination angle A of 1 (first connecting body 2) is inclined by about 4.5 degrees.

In such an insertion state, when the posture of the human body changes in daily life or the like, various types of movements occur, and the first connecting member 2 is inclined with respect to the second connecting member 3. For example, as shown in FIG.
The contact surface of the movable projection 11 of the upper first coupling body 2 with respect to the receiving surface 15 slides back and forth, and the upper second coupling body 3 is in a rotating state. Alternatively, as shown in FIG. 6, the movable projection 11 of the first connector 2 is rolled on the receiving surface 15 of the second connector 3 in the second state.
The connecting body 3 rotates, and the horizontal position of the upper second connecting body 3 with respect to the lower first connecting body 2 moves. Also, artificial disc 1
The above two examples have been shown as examples of the movement form, but these may occur at the same time, and the artificial disc 1 has mobility and motility due to the combination of these.

The angle of inclination of the first connector 2 and the second connector 3 is determined at the time of insertion and at the time of exercise. However, depending on the state of insertion into the diseased part, the angle between the artificial disc 1 and the first connector 2 is determined. The vertical gap T1 and the horizontal gap T2 (see FIG. 3A) are also partially expanded and contracted. And in what is shown in FIGS.
The forward tilt angle B when bending forward can be about 14 to 15 degrees,
It is preferable to set the interval between the vertical gap T1 and the horizontal gap T2 so that the backward tilt angle C at the time of bending backward can be about 6 to 8 degrees.

The front and rear inclination angles B and C at the time of bending forward or backward are in accordance with the state of a healthy person, but the first connecting body 2 and the second connecting body 3 At the time of manufacture, even if both base parts 10 and 12 are set to be in a parallel state, they are inserted at a predetermined angle when attached to a diseased part of the human body,
Sufficient mobility is ensured. That is, the widths of the upper and lower gaps T1 and the horizontal gaps T2 are set to allow the insertion state and the movement state after the operation.

Next, the kinematics of flexion of the spine in the anterior-posterior direction will be additionally described. The healthy intervertebral disc of the human body has different heights in the anterior part (abdominal) and posterior part (dorsal side). That is, because the anterior part is slightly higher than the posterior part, the lumbar and cervical vertebrae are
There is a curved part in front, and it is physiologically a lordosis (backward warpage). The motion of the lumbar spine and the like is not a simple three-dimensional motion centered on a specific point, but includes, for example, a slight parallel movement state in the front-back direction. The present embodiment has a form similar to such a complicated movement form as described in the above description of the operation.

Hereinafter, a modification of the first embodiment will be described. As shown in FIG. 7, in the artificial disc 1 of the second embodiment,
The receiving surface 15 of the first embodiment has a lower horizontal surface 16 at the center and a higher arc surface 17 around the center, as compared with the receiving surface 15 at the lower center. In the artificial disc 1 according to the third embodiment shown in FIG. 8, the receiving surface 15 is a horizontal surface 16.

Further, in the artificial discs 1 of the fourth and fifth embodiments shown in FIGS. 9 and 10, the material of the inner surface layer 18 of the movable receiving portion 13 of the second connector 3 is changed. FIG. 9 shows a structure in which the inner surface layer 18 of only the receiving surface 15 is changed.
0 indicates the receiving surface 15, the inner layer 18 and the top layer of the embankment 14,
19 has also changed. Although the shape shown is only the shape corresponding to the first embodiment, it is of course applicable to the second and third embodiments.

The materials of the first connector 2 and the second connector 3 in the first, second and third embodiments, and the fourth and fifth connectors
The materials of the first and second connectors 2, 3 and the inner surface layer 18 and the top end layer 19 in the embodiment have biocompatibility (affinity), mechanical strength, corrosion resistance and other in vivo stability. Made of material. For example, the first connector 2 and the second connector 3 are made of stainless steel, titanium, tantalum, platinum, an alloy thereof, or the like, and are processed into predetermined dimensions and shapes, and are particularly connected to the vertebral bodies M1 and M2. Side surfaces 6 and 7 and fixing projections 20,
20a ... is coated with hydroxyapatite and other affinity materials with excellent biocompatibility.

The first connecting member 2 and the second connecting member 3 may be made of a ceramic material having biostability, such as alumina, zirconia, or apatite, instead of metal. A material having properties or a surface-treated material can be appropriately changed. The materials of the inner surface layer 18 and the top end layer 19 are the first connector 2 and the second connector 3.
A material having low abrasion due to contact friction or the like can be used at the time of the movement. For example, a polymer resin having a hardness that does not compressively deform when inserted into a human body, for example, polyethylene or the like is used.

[0020]

In summary, according to the present invention, the artificial disc 1 is composed of a pair of upper and lower first and second connecting bodies 2, 3, so that the artificial disc 1 has only two members, and its manufacture is easy. The setting of the first and second connecting bodies 2 and 3 as two members can also be easily performed.

A movable projection 11 having an arc-shaped cross section is integrally formed on the opposed inner surface 4 of the base portion 10 of the first connected body 2, and a movable projection 11 having an arc-shaped cross section is formed on the opposed inner surface 4. Since the movable receiving portion 13 is formed in the inner surface 5 by depression,
Since the movable protrusion 11 of the first connector 2 has a rotatable and slidable mobility on the receiving surface 15 of the connector 3, motility is given to the spine on which the artificial disc 1 is mounted, and The function can be restored and the daily life is not hindered, or the healthy vertebral body and the intervertebral disc can be prevented from reoccurring, and recurrence can be prevented.
Also, the receiving surface where the tip of the movable projection 11 contacts the movable receiving portion 13
Since the movable projection 11 is configured by the projection 15 formed around the receiving surface 15 and the movable projection 11 changes its position and orientation within the movable receiving portion 13, the movable projection 11 moves from the movable receiving portion 13, that is, The first connector 3 does not come off from the second connector 3 and stability can be improved. In addition, a vertical gap T1 is provided between the opposing inner surface 4 of the base portion 10 of one of the first connecting bodies 2 and the top end of the bank 14, and a horizontal gap T2 is provided between the outer periphery of the movable projection 11 and the inner circumference of the bank 14. Therefore, the momentum can be secured by appropriately setting the vertical gap and the horizontal gap T1 and T2, and excessive movement in each direction can be restricted by the levee body 14 and the like, and safety can be secured.

The receiving surface 15 has a lower circular arc surface 17 at the center or a horizontal surface 16 at the center of the receiving surface 15 and a higher circular arc surface 17 around the horizontal surface 16. As a result, it is easy to approach the center, easily form a line that matches the center of the spine as a whole, and because the receiving surface 15 is formed as a horizontal surface 16, it is easy to perform a movement accompanied by forward and backward movement.

Further, since the inner layer 18 of the receiving surface 15 or the inner layer 18 and the top end layer 19 of the embankment 14 in the movable receiving portion 13 are made of a material having low abrasion, the movable projection 11 and the receiving surface are formed. Even by the movement between the members 15, the receiving surface 15 is hardly worn, the life and the functionality can be maintained, and the shock at the time of the contact of the embankment body 14 with the top end layer 19 can be reduced.

When the artificial disc 1 is attached to a diseased part, one of the first connectors 2 is connected to the other of the second connectors 3.
Is in an inclined state, and in the exercise state, one first connecting body 2 is moved forward by about 1 with respect to the other second connecting body 3.
Since it is possible to incline by 4 to 15 degrees and backward by about 6 to 8 degrees, it is possible to impart natural motility by enabling the exercise state similar to the healthy state. Also, a plurality of fixing projections 20, 20 are provided on the outer surfaces 6, 7 of the two connecting bodies 2, 3.
are provided, so that the fixing to the vertebral bodies M1 and M2 can be reliably performed, and the practical effect is extremely large.

[Brief description of the drawings]

1 is a side view and a front view of an artificial disc according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a sectional view taken along the line AA and a sectional view taken along the line BB of FIG. 2;

FIG. 4 is a sectional view of a main part showing a state of insertion into a diseased part.

FIG. 5 is a cross-sectional end view of a main part showing a state in which an upper connecting body rotates and slides on a contact surface to be inclinedly displaced in the inserted state of FIG. 4;

FIG. 6 is a cross-sectional end view of a main part showing a state where the contact surface rolls and rotates with the contact surface in the inserted state of FIG.

FIG. 7 is a cross-sectional view of the artificial disc of the second embodiment in which the center of the receiving surface is a horizontal plane.

FIG. 8 is a cross-sectional view of the artificial disc of the third embodiment in which the entire receiving surface is a horizontal plane.

FIG. 9 is a cross-sectional view of the artificial disc of the fourth embodiment in which the inner surface layer of the receiving surface is made of a different material.

FIG. 10 is a cross-sectional view of an artificial disc of a fifth embodiment in which the inner surface layer of the entire movable receiving portion including the receiving surface is made of a different material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Artificial disc 2 1st connection body 3 2nd connection body 4 Opposing inner surface 5 Opposing inner surface 6 Outer surface 7 Outer surface 10 Base part 12 Base part 11 Movable projection 13 Movable receiving part 14 Embankment body 15 Receiving surface 16 Horizontal plane 17 Arc Surface 18 Inner layer 19 Top layer T1 Vertical gap T2 Horizontal gap

Claims (8)

[Claims] 1. An artificial intervertebral disc comprising a pair of upper and lower connected bodies, wherein a movable projection having an arc-shaped cross section is integrally formed on an opposing inner surface of a base portion of one connected body, and a base of the other connected body. A movable receiving portion is formed in a recess on the opposing inner surface of the portion,
The movable receiving portion is constituted by a receiving surface with which the tip of the movable projection comes into contact, and a ridge protruding around the receiving surface. An artificial intervertebral disc having a gap and a horizontal gap between the outer periphery of the movable projection and the inner periphery of the embankment. 2. The artificial intervertebral disc according to claim 1, wherein the receiving surface has a low circular arc surface at the center. 3. A central part of the receiving surface is a horizontal plane,
2. The artificial disc according to claim 1, wherein an outer periphery of the horizontal plane is a high arc surface. 4. The artificial disc according to claim 1, wherein the receiving surface is a horizontal plane. 5. The movable receiving portion according to claim 1, wherein the inner surface layer of the receiving surface is made of a material having low wear resistance.
2, 3 or 4 artificial discs. 6. The embankment body and the inner surface layer of the receiving surface in the movable receiving portion and the top end layer of the embankment body are made of a material having low wear properties. Artificial disc. 7. When attaching an artificial disc to a diseased part, one connecting member is inclined with respect to the other connecting member, and one connecting member is connected to the other connecting member in an exercise state. Approximately 14 to 15 degrees forward, approximately 6 to rearward
The artificial disc according to claim 1, 2, 3, 4, 5, or 6, wherein the artificial disc can be tilted by 8 degrees. 8. The method according to claim 1, wherein a plurality of fixing projections are provided on outer surfaces of the two connecting members.
5, 6 or 7 artificial discs.