JP3350080B2 - Artificial vertebral body spacer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial vertebral body spacer to be loaded between vertebral bodies to correct a vertebral curve deformation which hinders the prone movement such as a walking disorder.

[0002]

2. Description of the Related Art Spine kyphosis, in which the spine curves backward and lays forward, and scoliosis, in which the spine curves laterally and lie down, are caused by lumbar spine deformation. It is often seen in women engaged in agriculture who often bend down and work, and there are many obstacles that hinder daily life, such as gait disturbances such as locomotion due to hip bending and its specific back pain.

For such a case, Japanese Patent Application Laid-Open No. 2-215461 proposes hitherto driving a bone fragment of an autogenous bone as large as possible between vertebral bodies and further driving the bone fragment. Orthodontic surgery has been performed using a metal plate or rod on which a rubber is adhered to the surface.

[0004]

2. Description of the Related Art However, the above-described spinal curvature correction has the following problems. When bone fragments of autogenous bone are implanted between the vertebral bodies, the bones are implanted and the fusion of the vertebral bodies with the cancellous bone is good, but bone resorption is likely to occur in the direction in which the load is applied. There was a problem that the effect of the correction gradually diminished. In most cases, autogenous bones implanted between the vertebral bodies are collected from the iliac or fibula, but it is necessary to exfoliate the gluteus maximus and iliac muscle extensively in order to obtain a sufficiently large bone graft. There is. For this reason, there have been many inconveniences due to autologous bone transplantation, such as a long operation, an increased amount of bleeding, and a prolonged rest period after the operation. In addition, there were not a few cases in which the bone fragments came off even after the transplantation.

On the other hand, in the above-described correction using a metal plate or rod, correction between a plurality of vertebral bodies cannot be performed, so that correction may be performed while an excessive load is applied. Had fallen, broken, or deformed, and even damaged the spine.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has at least an upper surface and a lower surface which contact upper and lower vertebral bodies so as to be mounted between arbitrary vertebral bodies to correct a spinal curvature deformation. A polyhedral artificial vertebral body spacer comprising:
An artificial vertebral body spacer characterized in that the angle between the upper surface and the lower surface is 14 ° to 40 °, and the angle is substantially unchanged under a load received in a living body.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 1 shows an artificial vertebral body spacer (hereinafter, abbreviated as a spacer) 1.
(B) As shown in the cross-sectional view, it is a polyhedron having at least an upper surface 1a and a lower surface 1b that contact upper and lower vertebral bodies so as to be attached between arbitrary vertebral bodies to correct spinal curvature deformation. The angle θ between the lower surface 1a and the lower surface 1b is 14 ° or more.
40 °, and the angle is substantially unchanged under the load received in vivo. The spacer 1 is loaded between the vertebral bodies T, T from which the intervertebral disc L of the spine M is removed in a state where the curved spine M is returned to the normal position as shown in FIG.
As described above, the angle θ between the upper surface 1a and the lower surface 1b is 14
Since it is formed at an angle of 40 °, the curved spine M can be corrected to the normal position. Spacer 1
In order to assist in the correction of the spinal deformity caused by the spine M, a rod R is driven into a posterior portion of the spine M so as to support the spine M corrected to the normal position.

[0009] In particular, when the degree of curvature of the spine M is large, for example, a place where correction can be easily performed is selected, or a place where damage to the spine M and surrounding nerves can be avoided. By arbitrarily selecting a plurality of optimal portions and loading the spacer 1 therein, it is possible to prevent an unreasonable load from being applied to only a part of the spine M and to prevent the spacer 1 from falling off. .

Examples of the material of the spacer 1 include ceramic materials such as alumina, zirconia, and apatite;
At least one of the upper surface 1a or the lower surface 1b of the spacer 1 made of stainless steel, a cobalt chromium alloy, pure titanium, a metal material having no harm to the living body such as a titanium alloy, an ultra-high polymer material such as polyethylene, or the above-described material,
A porous layer (not shown) made of a material having excellent biocompatibility such as hydroxyapatite may be provided.

In the orthopedic surgery in which the spacer 1 is loaded, it is not necessary to extract bone, and even if necessary, a small amount of bone can be collected, and a large amount of bone can be collected as in the case where only autologous bone is transplanted. It does not need to be boned, and does not cause significant physical and mental distress to the patient and various inconveniences.

As described above, the upper surface 1a and the lower surface 1b of the spacer 1 are formed at an angle of θ = 14 to 40 ° for the following reason. If spinal curvature deformity is an indication for surgery, at least 25 ° correction is required to correct the spine M, and the number of vertebral bodies on which surgery is performed is safe up to three vertebral bodies, Forcibly operating between the four vertebral bodies is very dangerous. Considering in advance that the spacer 1 sinks into the cancellous bone of the vertebral body T and loses the correction angle by about 5 °, when the upper surface 1a and the lower surface 1b of the spacer 1 are formed at an angle of θ <14 ° with each other. If the spacer 1 is inserted between the three vertebral bodies of a patient who has kyphosis in three vertebral bodies, the necessary correction angle cannot be obtained, and the lower back pain is somewhat alleviated, but the lower back is completely bent. Cannot be corrected. Also, the upper surface 1a and the lower surface 1b of the spacer 1
Are formed at an angle of θ> 40 ° with respect to each other, the spacer 1 may slide forward of the body and fall off after the operation.

In the following embodiment, only differences from the first embodiment will be described.

Embodiment 2 FIGS. 3 and 4 show a projection 2 or 2a which is pressed into the cancellous bone of a vertebral body T and acts as a stopper for preventing its fall-off.
4 shows spacers 1 and 1 provided on the upper surface 1a and the lower surface 1b. The spacer 1 made of alumina shown in FIG. 3 has beam-shaped projections 2 and 2 integrally provided on the upper surface 1a and the lower surface 1b. A spacer 1 made of polyethylene shown in FIG. 1 is made of a spike-like titanium alloy and has a protrusion 2a having a large diameter portion formed into a screw shape to be screwed from the upper surface 1a and the lower surface 1b.
3 are provided on each of the side a and the side of the lower surface 1b.

The shape and size of the projection 2 (2a)
The number, arrangement, etc. may be determined according to each case.

Embodiment 3 FIG. 5 shows a spacer 1 made of a pure titanium or titanium alloy fiber mesh having a porosity of about 50%.
Since such a fiber mesh is porous, the cancellous bone of the vertebral body T grows and grows in the pores, and as a result, a strong connection with the vertebral body T can be achieved. Further, the elastic modulus of the spacer 1 made of pure titanium bulk is about 110,0.
390,0 for spacer 1 made of 00 MPa and alumina
In contrast to 00 MPa, the spacer 1 made of pure titanium or a titanium alloy fiber mesh has an elastic modulus of about 900 MPa and has a good load buffering action.

Embodiment 4 FIG. 6 shows that polyvinyl alcohol (hereinafter referred to as P) is interposed between fiber meshes F and F made of pure titanium or titanium alloy.
VA), which is made of a hydrogel
In this spacer 1, a PVA hydrogel is contained in the micropores of the adjacent portions F ₁ and F ₁ between the fiber meshes F and F and the block body P of the PVA hydrogel. Thus, the fiber meshes F, F and the block body P are combined.

In preparing the spacer 1 as described above, PVA having a degree of saponification of 95 mol% or more, preferably 97 mol or more and an average degree of polymerization of 1700 or more, preferably 5000 or more on the average of clay is prepared by adding water or dimethyl. PVA is added to a mixed solvent of water and a hydratable organic solvent such as sulfoxide (DMOS) by heating and dissolving to make 2 to 30% by weight of PVA.
A paste containing is prepared.

Next, a previously prepared porosity of about 50% 2
One of the fiber meshes F, F is placed at the bottom of a metal mold, the adjusted PVA paste is poured from above, and the other is placed in the mold from above, and a press molding machine is placed. After applying pressure from above, the contents are taken out of the mold, and the temperature of the PVA paste is immediately lowered using instantaneous cooling spray, and the fine holes in the upper and lower fiber meshes F, adjacent portions F ₁ , F ₁ The block body P made of PVA hydrogel is united between the fiber meshes F while holding the PVA only inside.

Further, this is immersed in ethyl alcohol, washed with heating and stirring for about one week, air-dried at room temperature, and further dried by vacuum drying for about three days. Subsequently, heat treatment is performed in silicone oil at a temperature of 100 to 180 ° C. for 1 to 72 hours, and after further immersion in water,
Finally, air dry at room temperature.

The spacer 1 manufactured in this manner is porous on the upper surface 1a and the lower surface 1b. The cancellous bone of the vertebral body T grows and grows on the upper surface 1a and the lower surface 1b. In addition to preventing falling out of the space, the blocker P of PVA hydrogel combined with the fiber mesh F, F had ideal flexibility and load buffering action.

Embodiment 5 FIGS. 7 and 8 show a spacer having a through-hole 3 penetrating the upper surface 1a and the lower surface 1b so that the cancellous bone of the vertebral body T grows inside and the fixation to the vertebral body T is strengthened. The spacer 1 made of a titanium alloy shown in FIG.
% Of the porosity of the vertebral body T is promoted into the fiber mesh 3a. In addition, the material of the spacer 1 is not limited to the titanium alloy alone, but is a metal material which is not harmful to living bodies such as stainless steel, cobalt chrome alloy, pure titanium, ceramic material such as alumina, zirconia, apatite,
Alternatively, a super-polymer material such as polyethylene may be used.

Embodiment 6 FIGS. 9 and 10 show that each of the upper surface 1a and the lower surface 1b has a depth of about 0.5 to 2 mm so that the cancellous bone of the vertebral body T grows and the fixation to the vertebral body T is strengthened. The spacer 1 shown in FIG. 10 has an alumina bead 4a bonded to the recess 4 with silica-based glass (not shown), and the cancellous bone of the vertebral body T is inserted into the recess 4. To promote the growth and production.

The shape of the spacer 1 is not limited to the one described above, but may be, for example, a horseshoe shape, a circle, an ellipse, etc. as shown in FIG. What is necessary is just to use what had a suitable shape and dimension according to it. As shown in FIG. 12, the upper surface 1a and the upper surface 1b of the spacer 1 may be formed in two directions at an angle of [theta] ₁ , [theta] ₂ = 14 to 40 [deg.]. It can be adapted to patients with both kyphosis and scoliosis.

[0025]

According to the artificial hip joint of the present invention, a polyhedral artificial vertebra having at least an upper surface and a lower surface abutting on upper and lower vertebral bodies to be mounted between arbitrary vertebral bodies for correcting spinal curvature deformation. A body spacer, wherein the angle between the upper surface and the lower surface is 14 ° to 40 °, and the angle is substantially invariant under a load received in a living body, so that the curved spine can be formed. It can be corrected without difficulty.

[Brief description of the drawings]

1A and 1B are diagrams showing an artificial vertebral body spacer, wherein FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view taken along line vv of FIG.

FIG. 2 is a side view showing a state where an artificial vertebral body spacer is loaded between vertebral bodies.

FIGS. 3A and 3B are views showing an artificial vertebral body spacer having upper and lower beam-like projections, wherein FIG. 3A is a perspective view and FIG. 3B is a side view.

4A and 4B are diagrams showing an artificial vertebral body spacer having spike-shaped projections on upper and lower surfaces, wherein FIG. 4A is a perspective view, and FIG. 4B is a sectional view taken along line ww of FIG.

FIG. 5 is a perspective view showing an artificial vertebral body spacer made of pure titanium or a titanium alloy fiber mesh.

FIG. 6 is a perspective view showing an artificial vertebral body spacer formed by combining a block body of polyvinyl alcohol hydrogel between upper and lower fiber meshes made of pure titanium or a titanium alloy.

FIGS. 7A and 7B are views showing an artificial vertebral body spacer having a through hole in a vertical direction, wherein FIG. 7A is a perspective view, and FIG.
3 is a sectional view taken along line xx of FIG.

FIG. 8 is a view showing an artificial vertebral body spacer in which a fiber mesh block is inserted into a through-hole, wherein (a) is a perspective view and (b) is a cross-sectional view taken along the line yy of FIG. FIG.

FIG. 9 is a view showing an artificial vertebral body spacer having concave portions on upper and lower surfaces, where (A) is a perspective view and (B) is z in FIG.
It is a -z line sectional view.

FIG. 10 is a diagram showing an artificial vertebral body spacer including alumina beads in concave portions on upper and lower surfaces, (a) is a perspective view,
(B) is a sectional view taken along the line uu in FIG.

11 is a perspective view showing a variation of the form of the artificial vertebral body spacer, wherein (a) is a horseshoe-shaped horizontal cross-sectional shape, (b) is a circular shape, and (c) is an elliptical shape. Show things.

FIG. 12 shows that upper surfaces 1a and 1b are connected to each other in two directions θ ₁ , θ ₂
FIG. 4 is a perspective view showing a spacer 1 formed at an angle of 14 to 40 °.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Artificial vertebral body spacer 2 Projection 3 Through hole 4 Depression 5 Glass 1a Upper surface 1b Lower surface F Fiber mesh P Block 4a Alumina beads θ Angle

────────────────────────────────────────────────── (5) References US Patent 5071437 (US, A) US Patent 5047055 (US, A) US Patent 4834777 (US, A) US Patent 4714469 (US, A) US Patent 4911718 (US, A) A) U.S. Pat. No. 4,946,378 (US, A) U.S. Pat. No. 4,579,769 (US, A) WO 91/5521 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61F 2/44 WPI ( DIALOG)

Claims (1)

(57) [Claims] 1. A polyhedral artificial vertebral body spacer having at least an upper surface and a lower surface abutting upper and lower vertebral bodies for mounting between arbitrary vertebral bodies to correct spinal curvature deformation. An artificial vertebral body spacer, wherein an angle between the lower surface and the lower surface is 14 ° to 40 °, and the angle is substantially unchanged under a load received in a living body.