JPS5841854B2 - Ceramic implant components for osteosynthesis - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic implant member for use in living bone grafts and wires, and is generally a ceramic implant member that is faithful to the outer dimensions of a cut bone portion to be joined.

Unlike conventional fired ceramic bodies obtained by firing compacted compacts or slip-cast compacts, the present invention is produced by hardening ceramic granules that have already been completely fired or semi-fired at grain boundaries. This is a ceramic implant member for osteosynthesis that consists of the resulting porous ceramic body and a dense ceramic mantle that fits the porous ceramic body, and has extremely high dimensional fidelity as there is no change in volumetric dimension due to firing. It maintains high strength even after being attached to the bone cut site, and furthermore, by adjusting the gap between the porous particles, it allows the subsequent invasion of osteogenic tissue and achieves strong site fixation based on interlocking. It is characterized by

The present applicant has already applied for a ceramic implant member made of the above-mentioned sintered granules as a ceramic implant member to be applied to a tooth extraction socket immediately after a tooth extraction. It is known that the same effect can be expected not only in tooth extraction sockets, but also in implant members for osteosynthesis, as shown in the Examples below, and therefore, the present invention is intended to be provided.

The present invention will be explained in detail below based on the drawings. Figure 1 is a cross-sectional view of the main part when the member of the present invention is used for joining a femur, and Figure 2 is a cross-sectional view of the porous structure in Figure 1. An enlarged schematic view of the ceramic body is shown.

Implant member (■) of the present invention consists of ceramic granules 1...
・ is molded into a predetermined implant mold, and the contact grain boundaries are sintered by heating to form an aggregate of the above-mentioned granules 1 . Interparticle gaps that allow penetration of bone tissue 3.
It has a structure in which a porous ceramic body i comprising a porous ceramic body i and a mantle tube made of dense ceramics is fitted on the outer periphery of the porous ceramic body i.
The porous ceramic body i is joined to the fracture end g10g1 of g, and the dense ceramic mantle is joined to bridge the fracture end.

As a result, the new bone tissue from the femur g and g is transferred to the fracture end g1.
.

gl into the interparticle spaces of the porous ceramic body i, and the interlocking action of the new bone ensures strong fixation of the in-brand member (ii).

In addition, the dense ceramic mantle acts as a reinforcing member for the porous ceramic body, and new bone formation from the femur g-g invades the porous ceramic body i, and the femur g-g of the porous ceramic body i Provides sufficient mechanical strength to prevent damage from external forces applied until firm fixation to g is achieved.

Next, the basic manufacturing process for obtaining such a structure will be explained together with materials.

In order to obtain strength, the ceramic granules to which the porous ceramic body i of the present invention is applied are preferably completely sintered or semi-sintered alumina ceramics or zircon ceramics.

The particle size of these granules is such that the diameter of interparticle gaps 3, which will be described later, is set to allow entry of new bone tissue. 0.2~0.7
In order to obtain particles of mmφ, the diameter of most of the granules is 0.5~
The diameter should be approximately 2.0 mmφ.

In this case, in order to make the diameter of the formation gap as uniform as possible, granules 1
It is necessary to make the diameters of ... as uniform as possible.

The reason for using a sintered or quasi-sintered body is that if alumina or zircon oxide powder is used as it is, the volume will shrink significantly due to sintering, making it impossible to obtain a product that matches the actual implant mold, resulting in a problem with filling. This is to prevent the volume shrinkage by pre-firing C, since this would leave a fatal problem of impossibility.

It is also extremely effective in maintaining the grain shape during molding, that is, preventing deformation and destruction of the granules, and also in maintaining appropriate interparticle gaps.

A desirable method for forming such ceramic granules 1... into a predetermined implant shape is to form these granules 1...
An organic binder (CMC,
(PVA, etc.) or waxing material, etc. to make a clay-like plastic material, and shape it into a predetermined implant mold, or make a mold compatible with the implant mold in advance and place the above granules and binder in it. It is also possible to fill the mixture with "C" and pressure mold it.

Also, take an impression of the cut part of the biological bone to be repaired, create a model of the cut part based on this impression, form a cavity corresponding to this model using precision casting investment, and insert the above-mentioned cavity into this cavity. It is also possible to cast and shape the granular material.

Next, the thus obtained compact is heated to a temperature at which a sintering reaction occurs at the grain boundaries in order to cause grain boundary sintering.

In the case of alumina ceramic granules, this heating temperature is 14
In the case of zircon ceramic granules, the heating temperature is in the range of 00 to 1,600°C, and in the case of zircon ceramic granules, it is in the range of 1,300 to 1,400'C. The surface of each particle of the above-mentioned granules 1... is made of glass, especially a material whose coefficient of thermal expansion is similar to that of the ceramic used, which has a melting point lower than the sintering temperature of the ceramic, and which has a low viscosity region near the melting point. In the case of alumina ceramic granules, a thin coating of randane glass (not shown) is desired.

With this lanthanum-based glass coating, the sintering temperature can be lowered to 1,000 to 1,200°C, and the viscosity decreases rapidly at the melting point, causing the glass to be concentrated at the contact point between the granules 1. By expanding the contact surface, particle bonding force can be improved.

As shown in Figure 2, by the heating described above, the grain boundaries of ceramic granules 1 were sintered and hardened 2 to form aggregates of granules, with interparticle gaps 3 rooted in a net shape. Porous products can be obtained, but due to the application of sintered (completely or semi-sintered) ceramic granules 1..., there is almost no shrinkage during firing, and therefore the ink that almost matches the actual external dimensions can be obtained. A blunt type is obtained.

At this time, the interparticle gap 3... is the ceramic granule 1.
The particle size selection 1 for ... can be easily estimated in advance, but the gap 3 suitable for the invasion of new bone tissue is 0.
．． 2 to 0.7 amφ, such a gap 3.
A granule size that yields... should be selected.

In this case, as another auxiliary means for forming gaps, 30 to 200 meshes of acrylic resin particles and other volatile particles (not shown) that are thermally decomposed and volatilized at the sintering temperature and do not leave any ash are added along with the ceramic granules 1. In comparison, when ceramic granules 1 contain 0.5 to 1φ, it is easy to form the interparticle gaps 3 that form porosity uniformly, and the particle size of granules 1... There is an advantage that particles having a particle size smaller than the required size can be used without having to prepare them in advance.

In addition, the dense ceramic mantle tube in the implant member (2) of the present invention is formed into a tubular shape from a dense polycrystalline or single crystalline ceramic, and is made of alumina ceramic, zircon ceramic, etc. by ordinary powder compacting or slip casting. A polycrystalline product formed by molding and firing, or a single crystallized product pulled from the molten salt is used. The implant member (2) of the present invention is the above-mentioned tubular dense ceramic mantle. Insert the porous ceramic body i into the pipe and heat it to sinter and harden the inner wall surface of the dense ceramic outer pipe and the granules of the porous ceramic body i in contact with the inner wall surface. It can be obtained by

The present invention will be explained in more detail below by giving examples.

(Example 1) [Porous ceramic body] (a) Granules: alumina ceramic granules with a particle size of 1 to 2 mm.

(B) Molding method: Prepare a clay-like plastic material by mixing 80 parts of the granules in (A) with 20 parts of a 10% PVA (polyvinyl alcohol) aqueous solution and 2.0 parts of naphthalene powder (60 to 100 mesh). did.

On the other hand, as shown in FIG. 1, the fracture end g1 of the fractured femur gg.

The external shape and dimensions of GL have been verified in advance using X-rays, and the external shape matches that.

A porous ceramic body of the same dimensions was modeled by hand kneading.

(/→ Sintering conditions... By heating this element body to 1550°C, a porous alumina ceramic body i with an interparticle gap of 0.3 to 0:8 φ is obtained.

[Dense ceramic mantle]

A conventionally well-known alumina ceramic powder was compacted into a tube shape and fired at 1600° C. to obtain a jacket tube made of polycrystalline dense ceramics.

The above-mentioned porous alumina ceramic body i is inserted into a dense ceramic jacket tube, heated at 1500'C,
A porous alumina ceramic body i and a dense ceramic mantle were sintered and integrated to form a ceramic implant member for osteosynthesis.

[Joining instructions]

The above-mentioned osteosynthesis ceramic implant member (1) was attached to the fracture end g1 of the femur gg.

The porous ceramic body i is placed at the abutting site between the fracture ends g1.

gl, and the dense ceramic mantle tube is placed so as to bridge the fracture ends g1-g, and a splint is placed on the outside of these joints to maintain that state for several months. After removing the dorsal splint, the left and right femoral fracture ends g1.

It was confirmed from gl that the new bone tissue had invaded into the interparticle spaces of the porous ceramic body i, interlocked with each other, and that the bonding was sufficiently performed.

From the description, the implant member of the present invention is made by fitting a porous ceramic body, which is an aggregate of ceramic granules that is almost the same size and shape with respect to the implant mold, in a dense ceramic jacket tube. In addition to ensuring a dimensionally accurate implant, the gap between porous particles can be easily adjusted, and it has the excellent effect of achieving strong site fixation based on the interlocking of skeletal tissues. No external stress is directly applied to the porous ceramic body until the invasion of the new bone tissue into the porous ceramic body is completed, and no damage occurs due to the application of external stress.

The method of manufacturing an implant component of the present invention also has the advantage of being easily implemented by orthopedic surgeons.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main parts when the implant member of the present invention is used for joining the femur, and Fig. 2 is a partially enlarged schematic diagram of the porous ceramic body in Fig. 1. . Explanation of symbols, 1... Ceramic condyles, 2...
...Grain boundary sintered part, 3... Interparticle gap, i.
... Porous ceramic body, ■ ... Ceramic implant member for osteosynthesis, g ... Femur, gl ... Fracture end, h ...・A mantle tube made of dense ceramics.

Claims (1)

[Claims] 1 Ceramic granules are molded into a predetermined implant mold, which is heated to harden the contact grain boundaries and become an aggregate of the granules, which has an external shape with approximately the same dimensions and shape as the implant mold, and the invasion of new bone tissue. 1. A ceramic implant member for osteosynthesis, characterized in that a porous ceramic body is fitted with a dense ceramic mantle tube, and a porous ceramic body is provided with interparticle gaps that allow for.