JPS63109867A - Living body prosthesis - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bioprosthetic member used in the medical fields such as orthopedics, neurosurgery, oral surgery, dentistry, and the like.

(Prior art) Conventionally used bioprosthetic components made by compressing and accumulating metal wires include short wires made by cutting short metal wires that have been pre-corrugated, or long continuous wires that are corrugated and then compression molded. It was manufactured by vacuum firing.

Such a bioprosthetic member has an elastic modulus close to that of bone, and when applied to a living body, pores are formed in at least the surface portion to allow penetration of bone tissue.

(Problems to be Solved by the Invention) However, the elastic modulus of such prosthetic members is non-uniform, and furthermore, there is a large variation among individual products. Therefore, the stress acting on the living body cannot be set to a constant value, and stable and high-quality therapeutic effects cannot be achieved. In addition, the strength is insufficient, making it difficult to use as a prosthetic member for areas subject to large loads.

In addition, the distribution of pores present on the surface is uneven, and the size and average pore diameter vary greatly among individual products. Such a bioprosthetic member has the drawback that the creation and invasion of living tissue does not occur in a similar manner, and good stable fixation with the living body cannot be achieved.

(Means for solving the problem) In view of the above, the variation in elastic modulus and average pore diameter is small;
In order to obtain a prosthetic member in which the distribution width of pore diameters is narrow and evenly distributed, metal wires are formed into a network in advance, and several sets of metal wires are compression-molded into a desired shape. Construct a bioprosthetic member.

(Example) Hereinafter, the present invention will be specifically explained in detail with reference to Examples.

(Example 1) After braiding pure titanium wire rods with wire diameters of 56, 250, and 500 μm to make gold 'fI41 in the shape shown in FIG. 1, this wire mesh 1 was rolled to form a mold with a circular cross section of 20 mm in diameter. The wire rods having wire diameters of 50, 250 and 500 μm were press-formed using a hydraulic press to obtain an aggregate having a porosity of about 5 oz. Each of the 20 pieces of φ20 X obtained in this way
Of the 101 aggregates, 10 remain unsintered and the other 1
0 pieces were vacuum sintered at about 1350°C. Among these two groups of test pieces, the group that was pressure-formed and unsintered was defined as the first group of products of the present invention, and the group that was further subjected to a vacuum sintering process was defined as the second group of products of the present invention.

Next, for comparison, test pieces were also produced using the conventional method. That is, a pure titanium wire with a wire diameter of 50.250.500 μm is given a sinusoidal wave with a period of about 5.0 mm and an amplitude of about 1.0 mm, and then it is rolled into a mold with a circular cross section of 20 mm in diameter. Filled, wire diameter 50μm, 250μm
10MPa, 50MP depending on m, 500 pm respectively
a. Pressure molded at a pressure of 150 MPa to achieve a porosity of approximately 50
We obtained an aggregate of χ.

Further, this was vacuum sintered at about 1350°C. Ten aggregates of φ20×10 N thus obtained were used as a first group of conventional products.

On the other hand, pure titanium wires with wire diameters of 50 μm, 250 μm, and 500 μm have a period of about 5. On+n+, a sine wave-like wave with an amplitude of 1.0 mm is applied, and then cut into short lines of about 30 mm in length.

A large number of short wires obtained in this way were vertically filled into a mold having a circular cross section of φ20 mm, and the wire diameter was 50 μm and 250 pe.
a, 10MPa and 50MPa respectively according to 50071m
a. Pressure molding was performed at 150 MPa to produce an aggregate with a porosity of approximately 50χ. Further, this was vacuum sintered at about 1350°C. 10 pieces of φ20 each according to the wire diameter obtained in this way.
The test piece group of X10A was designated as the second group of conventional products.

Using an image analysis device, the average pore diameter and pore distribution were measured for a total of 12 types of test specimens in 4 groups produced as described above. In addition, the compressive elastic modulus and fracture stress were measured by a compression test. Table 1-2 shows the relationship between the pore diameter distribution range and the wire diameter, Table 1-1 shows the relationship between the average pore diameter and the wire diameter, and Table 2 shows the relationship between stress - compressive elastic modulus - wire diameter. The relationships are shown below.

Among these, Table 1-2 shows the pore diameter distribution ranges of 12 types of prosthetic members in 4 groups as examples. However, this is shown in Figure 2.
This is defined as the range of pore diameters in which pores exist in the pore diameter-frequency histogram.

According to this, there is almost no difference between the first group and the second group of the products of the present invention, but the first group and the second group of the products of the present invention are the same as the first group of the conventional product.
The width of the pore size distribution is narrower than that of Group 2.

Table 1-1 shows the average pore diameters of 10 specimens of 12 types in 4 groups, and the standard deviations of the 10 specimens. The average values of a total of four groups, Group 1.2 of the present invention product and Group 1.2 of the conventional product, were approximately the same.

However, the standard deviation indicating the variation in the average pore diameter of the 10 prostheses is small for the products of the present invention in Groups 1 and 2, whereas the standard deviations of Groups 1 and 2 of the conventional products are both smaller than the former two groups. ~
Three times bigger.

(Left below) Table 1-2 Relationship between pore diameter distribution range and wire diameter No. 2
The table shows the pressurization speed of 0.5 mm for 10 various groups in 4 groups.
A compression test was carried out at 1/min, and the resulting stress strain curve as shown in FIG. 3 was analyzed to determine the compressive elastic modulus.

According to this, the compressive elastic modulus varies depending on the stress, and for each stress 0.5.1.0.3. A typical stress-compressive modulus curve, defined as the slope of the tangent to each stress strain curve at the point OMPa, is shown in FIG.

Furthermore, it can be seen from Table 2 that 1) the first group of products of the present invention has a significantly lower compressive modulus of elasticity than the second group of products of the present invention and the conventional products group 1.2; 2) Both the first and second groups of the products of the present invention have small standard deviations, which are about 173 to 174 for the conventional products of groups 1 and 2.

(Margins below) On the other hand, Table 3 shows the relationship between the value of fracture stress in the compression test and the diameter of the wire rod. The value of this fracture stress is defined as the stress at which the compressive elastic modulus starts to decrease as the stress increases in the stress-compressive elastic modulus curve shown in FIG. The following can be seen from Table 3. 1) The breaking stress of the second group of products of the present invention is significantly higher than that of the first group of products of the present invention. 2) The breaking stress of the first group of products of the present invention was comparable to that of the first and second groups of conventional products.

(Left below) (Example 2) Pure titanium wire with a diameter of 250 μm was woven into a net shape, and
Fill a mold with a rectangular cross section of mm x 7 mm, and
Pressure molded at a pressure of 0 MPa, with a porosity of approximately 50! , about 5
A rectangular parallelepiped test piece measuring mm x 5 mm x 7 mm was obtained. This was vacuum sintered at about 1400°C. The test piece thus obtained was implanted between a peagle-sized femur and lower lumbar vertebrae, layered at 3, 6, 24, and 36 weeks, and the bone tissue surrounding the sample was taken out and observed under a microscope. As a result, better bone invasion was observed in both the femoral bone implantation group and the lower lumbar intervertebral implantation group from 3 weeks onwards, and this progressed further at 6 weeks, and by 36 weeks, the bone had reached the center of the specimen. . This situation is shown in Figure 5, which shows the tissue structure of the femur implantation group at 6 weeks as a photograph.

In addition to the above examples, even when using zirconium wire, titanium alloy wire, or Co--Cr wire, uniform and high-strength auxiliary members were obtained by knitting the wire into a net shape and compression molding.

(Effects of the Invention) As described above, by knitting metal wires into a net shape and molding this into an aggregate, it is possible to provide a bioprosthetic member that is uniform and has high strength.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an example of a wire mesh forming a bioprosthetic member according to the present invention, Fig. 2 is a graph showing the relationship between the pore diameter of the bioprosthetic member and its frequency, and Fig. 3 is a graph showing the stress distortion due to stress. It is a graph diagram showing a curve. Figure 4 is a graph showing the stress-compressive modulus relationship;
The figure is a photograph showing the tissue structure when the bioprosthetic member of the present invention is implanted in a living body. 1...wire mesh

Claims (2)

[Claims] (1) A bioprosthetic member consisting of an assembly of metal wires formed by forming the metal wires into a net-like body in advance and compression-molding the net-like body into a desired shape. (2) The bioprosthetic member according to claim 1, wherein the metal wire has a wire diameter of 200 to 500 μm.