JPH084606B2 - Artificial disc - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an artificial intervertebral disc used for treating diseases such as herniated intervertebral disc and damage to the spine due to an accident.

[Conventional technology]

As shown in FIG. 7, the spine of the human body is composed of hard vertebral bodies 1 arranged in a row and a cartilage intervertebral disc 2 connecting vertically adjacent vertebral bodies 1. When the above-mentioned spine disease or damage is severe, surgical treatment is performed by removing all or part of the vertebral body 1 and the intervertebral disc 2 by incision surgery, and implanting autologous bone or artificial vertebral body in the portion. It is being appreciated.

As such an artificial vertebral body, conventionally, as shown in FIGS. 8 and 9, an alumina ceramic molded into a substantially disk shape or a rectangular parallelepiped shape is used.
In addition, recently, known bioactive ceramic materials having an apatite crystal phase, materials obtained by blending high density polyethylene or methacrylate resins, and the like have been used.

[Problems to be Solved by the Invention]

However, all of these artificial vertebral bodies are merely used as spacers that fill the gap and support the load when the intervertebral disc or the like is excised, and the flexibility like the vertebral body that sandwiches the original intervertebral disc is used. There is no. Therefore, it is difficult to follow the movement of the human body, and an excessive load often damages the treatment area or its peripheral portion again, which is a problem.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a flexible artificial intervertebral disc that can sufficiently follow the movement of the human body.

[Means for solving the problem]

In order to achieve the above object, the artificial intervertebral disc of the present invention has two substantially plate-shaped bodies made of a bioactive ceramic material on the upper surface and the lower surface of the substantially plate-shaped body made of a biocompatible polymer elastic material. Each of them is integrally attached.

[Action]

That is, in contrast to the conventional artificial vertebral body having a hard block shape, the present invention sandwiches a substantially plate-shaped body made of an elastic polymer from both upper and lower sides with a substantially plate-shaped body made of hard ceramics, and is provided with a sun-germany structure. It is structured. Therefore,
If the upper and lower ceramic parts of this artificial disc are joined to the vertebral bodies in the living body, the upper and lower ceramic discs center around the elastic polymer plate as if the intervertebral discs flexibly connect the upper and lower vertebral bodies. Turn freely to some extent. Therefore, the artificial intervertebral disc flexibly moves in accordance with the forward bending, backward bending, etc., so that the entire spine moves smoothly and no excessive load is applied. In addition, the artificial disc is divided into three parts, the upper and lower ceramic parts and the central elastic body part, so by appropriately selecting the shape and material of each part, the balance with the physique of the patient and other spinal functions is achieved. It is possible to provide an artificial intervertebral disc that fits the person while observing the like, and to give a detailed treatment.

 Next, the present invention will be described in detail.

The artificial intervertebral disc of the present invention has, for example, a three-layer structure as shown in FIG. That is, the upper and lower two layers are both formed of hard disc-shaped bodies 10 and 11 made of ceramics, and the intermediate layer sandwiched between the two layers is formed of a disc-shaped body 12 made of an elastic polymer. There is.

Ceramic disks 10 and 11 for the upper and lower layers
Is required to have bioactivity that chemically binds to bone and becomes inseparable, and is made from a bioactive ceramic material. Examples of the ceramic material include hydroxyapatite, bioglass,
Examples include glass ceramics. Of these, glass ceramics containing apatite-wollastonite, which is a crystallized glass, is suitable.

On the other hand, the polymer disc 12 sandwiched between the ceramic discs 10 and 11 needs to have biocompatibility and a certain elasticity, and is made of, for example, biogenic silicone rubber or biogenic urethane rubber. . Moreover, you may use the silicone resin or urethane resin to which elasticity was given by foaming. However, these polymeric elastic materials have hardness (JIS
It is desirable that A) is in the range of 10 to 50 degrees. Hardness 1
If the angle is less than 0 degrees, it is too soft to be embedded in the middle of the spine, and this portion is easily deformed by the load and protrudes in the anteroposterior, leftward, and rightward directions, and it is not suitable because it presses the nerve tissue. On the other hand, if the hardness exceeds 50 degrees, the artificial intervertebral disc that is too hard loses flexibility and is inconvenient to use.

If rubber is used to mold the polymeric elastic material into a substantially disk shape, an unvulcanized (uncrosslinked) resin material is filled in a mold of a predetermined shape and vulcanized ( It may be crosslinked) and cured. When a foamed resin is used, a foamed resin having a predetermined shape may be cut into a disk shape.

The artificial intervertebral disc of the present invention can be obtained by placing the polymer disc 12 at the center and sandwiching the polymer discs 12 from above and below to integrally join the three discs. A biocompatible adhesive is used for the joining. Examples of such biocompatible adhesives include silicone-based coupling agents, titanium-based coupling agents, and aluminum-based coupling agents. Among them, silicone-based coupling agents are preferable.

Incidentally, in the artificial intervertebral disc of the present invention, the shape and thickness of the ceramic discs 10, 11 and the polymer disc 12, or the hardness of the elastic body layer, depending on the physique of the patient and the balance with other spinal functions. Can be set individually. For example,
As shown in FIG. 2, the outer peripheral surface of the polymer disk 12 may be recessed to make it easier to bend into a dogleg shape, or conversely, as shown in FIG. You may make it show a strong resistance to the load applied to the up-down direction by giving a convex roundness.

Further, projections (or streak-like grooves) as shown in FIG. 4 may be formed on the outer surfaces of the ceramic disks 10 and 11. In this way, the vertebral body (see FIG. 7) and the ceramic disc 10,1 when implanted in a living body.
The joint area with 1 becomes large, and the artificial intervertebral disc is firmly fixed.

Further, the upper and lower ceramic discs 10 and 11 and the polymer disc 12 are shaped so that one side of the circle is crushed, as shown in FIG. 4, imitating an actual spine. May be.

The upper and lower ceramic plates and the polymer plate are not limited to disc shapes, and square plates and other appropriate shapes can be used.

 Next, examples will be described together with comparative examples.

Examples 1 to 3 First, a disk of bioactive crystallized glass (diameter 40 mm, thickness
5 mm) were produced. In addition, silicone rubber (Q74720,
Made by Dow Corning, hardness 30 degrees), diameter 40mm, thickness 10
It was formed into a disk shape of mm. However, the circumferential surface was recessed. Then, these were joined by an adhesive (Primer A, manufactured by Shin-Etsu Chemical Co., Ltd.) to produce an artificial intervertebral disc as shown in FIG.

Also, the hardness of the silicone rubber is 10 degrees (Example 2), 50
Artificial intervertebral discs with different degrees (Example 3) were prepared.

The compression spring characteristics of the three types of artificial intervertebral discs thus obtained were measured by compressing the sample at a test speed of 1 mm / min. The result is shown in FIG.

[Examples 4 to 7] The types of the ceramics material of the ceramics disk and the polymeric elastic material of the polymeric disk were changed according to the following tables. An artificial intervertebral disc was prepared in the same manner as in Example 1 except for the above.

Then, the artificial intervertebral discs of Examples 1 to 7 were embedded in a cadaver specimen, and the anterior flexibility, the posterior flexibility, the axial twistability, and the lateral flexibility were measured, and compared with that of the actual intervertebral disc, the movement was good or bad. Was evaluated.

The results are shown in the table below. As a control example, the conventional artificial vertebral body shown in FIG. 8 was prepared and evaluated in the same manner as above, and the results are also shown in the table below.

From the above results, it can be seen that the products of the Examples all exhibit good spring compressibility and have excellent flexibility as compared with the control product.

〔The invention's effect〕

As described above, the artificial intervertebral disc of the present invention has a San-Gerench structure in which a substantially plate-shaped body made of a polymer having elasticity is sandwiched from both upper and lower sides by substantially plate-shaped bodies made of hard ceramics. The upper and lower ceramic plates freely rotate about a polymer plate to some extent. Therefore, the artificial intervertebral disc flexibly moves in accordance with the forward bending, backward bending, etc., so that the entire spine moves smoothly and no excessive load is applied. Further, since the artificial intervertebral disc is divided into three parts, the upper and lower ceramic parts and the central elastic body part, by appropriately selecting the shape and material of each part,
While looking at the patient's physique and balance with other spinal functions,
The person can be provided with an artificial intervertebral disc suitable for the person, and can be given detailed treatment.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a perspective view showing another embodiment, FIG. 3 is a perspective view showing yet another embodiment, and FIG. 4 is a ceramic disk. FIG. 5 is a perspective view showing a modified example, FIG. 5 is a plan view showing a modified example of the shapes of the ceramic disk and the polymer disk, FIG. 6 is a diagram showing the compression spring characteristics of the example product, and FIG. 7 is the spine. FIG. 8 is a partial perspective view showing the structure of FIG. 8, and FIGS. 8 and 9 are perspective views showing an example of a conventional product. 10, 11 ... Ceramic disc, 12 ... Polymer disc

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroaki Ishikawa 3-12-10 Momiji Tainan, Atsubetsu-ku, Sapporo, Hokkaido (72) Inventor Takehiro Shibuya 2-41-7, Motomiya, Otsu City, Shiga Prefecture Inventor Masataka Takagi 626, Kogoji Temple, Notogawa-cho, Kanzaki-gun, Shiga Prefecture (72) Inventor Yukio Sakuraba 3600 Amagatsu, Komaki-shi, Aichi Prefecture, Toyama Rubber Industry Co., Ltd. (72) Kiyoshi Baba, Komaki-shi, Aichi Prefecture Tsu 3600 Tokai Rubber Industry Co., Ltd. (56) Reference JP-A-2-215461 (JP, A)

Claims (3)

[Claims] 1. Two substantially plate-shaped bodies made of a bioactive ceramic material are integrally attached to the upper surface and the lower surface of the substantially plate-shaped body made of a biocompatible polymer elastic material, respectively. Characteristic artificial intervertebral disc. 2. The artificial intervertebral disc according to claim 1, wherein the bioactive ceramic material is bioactive glass or bioactive crystallized glass. 3. The artificial intervertebral disc according to claim 1, wherein the biocompatible polymeric elastic material is urethane rubber or silicone rubber.