JP2000189436A - Device for joining bone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for joining a bone which can join a living bone a part of which is cut and removed without extremely shortening the length and which can be dissoluted and absorbed in a living body. SOLUTION: This device for joining a bone D1 is formed from a polymer dissoluble and absorptive within a living body, and a pair of medullary cavity insertion pins 2, 2, having a diameter smaller than that of a central round block 1 is projected. Since the medullary cavity insertion pins 2, 2, are inserted into the medullary cavity of a living bone a part of which is cut and removed, the round block 1 as a spacer is joined at an interval between the living bones, thus a length of living bone can be prevented from shortening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable and resorbable osteosynthesis device.

[0002]

2. Description of the Related Art Metal and ceramic bone joints have been widely used. However, since such an osteosynthesis device has a much higher elastic modulus than that of a living bone, there is a problem that the strength of the surrounding bone is reduced by a phenomenon of stress protection after healing. In particular, metal osteosynthesis may have a bad effect on the living body due to elution of metal ions. Therefore, it is necessary to perform a reoperation in which the osteosynthesis is removed from the body as soon as the fracture or the like is healed. There is.

[0003] In view of such circumstances, a osteosynthesis made of biodegradable and absorbable polylactic acid, etc., which does not require reoperation, has recently been developed and attracted attention. By the way, there are various types of osteosynthesis such as screws, pins, and plates. For example, as a device for joining a rib or the like cut by an osteotomy, a biodegradable bioabsorbable material as shown in FIG. An osteosynthesis pin 100 is known. This osteosynthesis pin 100
The cut portions of the living bone 101 are joined by inserting the pins 100 into the medullary cavities 102, 102 on both sides of the cut portion of the living bone 101 from both ends, respectively. When joining, there were the following problems.

[0004]

That is, when an osteoma or the like is formed in a living bone, usually, as shown in FIG.
The bones 103 such as hip bones are filled from the bones, and the bones 103 are filled, and the bones are reconstructed by covering and prosthesis with a biodegradable and absorbable plate 104 or the like. However, if the osteomas cannot be completely removed by this method, the living bones 101 are cut off to completely remove the portions where the osteomas have been formed, and the osteosynthesis pins 100 are used to remove the osteomas. It is necessary to join the living bone 101
There is a problem that the length becomes shorter by the resection.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the purpose of the present invention is to provide a biodegradable bioabsorbable material capable of joining partially cut and removed living bone without changing its length. An object of the present invention is to provide an osteosynthesis. It is also desirable to increase the strength, fixation force, osteoconductive ability, etc. of the osteosynthesis.

[0006]

According to a first aspect of the present invention, there is provided an osteosynthesis device comprising a biodegradable and absorbable polymer, wherein the osteosynthesis device comprises a central circular block. A pair of medullary cavity insertion pins having a diameter smaller than the diameter of the circular block is protrudingly provided on both sides in the direction.

[0007] The osteosynthesis device having the above-mentioned structure is adapted to join the cut living bone by inserting the medullary cavity insertion pins on both sides of the circular block into the medullary cavity of the cut living bone, respectively. Can function as a spacer to join the living bones at intervals, so that the length of the joined living bones does not become extremely short unlike the related art. Then, the osteosynthesis device is hydrolyzed and absorbed over time in the living body, is absorbed, and is gradually replaced by growing bone tissue, so that the joint portion is reconstructed.

The term "circle" of a circular block does not only mean a true circle, but is a term encompassing all shapes close to a circle, such as a slightly distorted circle, an oval, and an ellipse.

Next, the osteosynthesis device according to a second aspect of the present invention is the osteosynthesis device according to the first aspect, wherein the outer peripheral surface of the medullary canal insertion pin has a tapered taper toward the tip of the pin. The surface part and the step part are formed alternately.

In the osteosynthesis having such a configuration, the medullary canal insertion pin can be inserted into the medullary canal of the living bone while the medullary canal is expanded by the tapered surface portion of the constriction. The operation of inserting the insertion pin can be easily performed. When the medullary canal insertion pin has been inserted into the medullary canal, the outer peripheral end of the step portion of the medullary canal insertion pin slightly bites into the inner surface of the medullary canal. As a result, the joint strength of the living bone is improved.

A third aspect of the present invention is directed to an osteosynthesis device according to the first or second aspect, wherein at least one of the medullary cavity insertion pins is curved. Things.

The osteosynthesis having such a configuration is suitable for joining a curved living bone such as a rib, and inserts a curved insertion pin into the medullary cavity of the curved living bone to insert the living bone. It can be joined in the original curved state.

The osteosynthesis according to a fourth aspect of the present invention is the osteosynthesis according to any one of the first to third aspects, wherein the osteosynthesis is forged with a biodegradable and absorbable polymer. It is characterized by being composed of a body.

[0014] The osteosynthesis made of such a forged molded article is composed of a compressed poly- body in which the molecular chains of the biodegradable and absorbable polymer, its aggregation domains, clusters, crystals, and the like are oriented along a number of reference axes having different axial directions. Since it is an axially oriented body, it is dense, has little strength anisotropy, and has high strength against external forces and torsional forces in various directions.

Next, a osteosynthesis device according to a fifth aspect of the present invention is the osteosynthesis device according to any one of the first to fourth aspects, wherein a bioceramic powder is contained. Things.

In the osteosynthesis having such a structure, the bone tissue is formed from the surface layer of the osteosynthesis into conduction by the bioceramic powder exposed on the surface and the bioceramics powder exposed by hydrolysis. Therefore, the osteosynthesis device and the living bone are combined within a relatively short period of time, and the fixing force is further improved. Further, since the replacement property with the bone tissue is also improved, the bone tissue can be replaced with the bone tissue in a shorter period of time than a bone connector containing no bioceramics powder, and the bonded portion can be reconstructed quickly.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of an osteosynthesis device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a usage state of the osteosynthesis device.

This osteosynthesis device D ₁ is made of a biodegradable and absorbable polymer. A pair of round rods having a diameter smaller than the diameter of the circular block 1 is provided on both axial sides of the central circular block 1. The medullary cavity insertion pins 2 and 2 protrude coaxially. The outer peripheral portions of the tips of the pins 2 and 2 are cut into tapered tapered surfaces 3 and 3 so that they can be easily inserted into the medullary cavity of living bone.

The central circular block 1 serves as a spacer for joining the cut living bones at intervals, so that the axial length (thickness) of the circular block 1 is, for example, It is desirable to set the diameter within a range of 3 to 20 mm in consideration of a resection size or the like when a lesion portion of a bone is resected, and the diameter of the circular block 1 is 2 to 40 mm in consideration of the thickness of a living bone. It is desirable to set within the range.

On the other hand, the thickness (diameter) of the medullary cavity insertion pin 2 is
It is desirable to set the distance in the range of 1 to 20 mm in consideration of the inner diameter of the medullary cavity of the living bone. The length of the medullary cavity insertion pin 2 is desirably set to about 4 to 30 times the diameter of the pin, and when the length of the pin is less than 4 times the diameter, the pin 2 There is a possibility that the pin 2 will fall out of the medullary cavity. Conversely, if it is longer than 30 times the diameter, it will be difficult to completely insert the pin 2 into the medullary cavity.

The biodegradable and absorbable polymer used as the material of the osteosynthesis device D ₁ has an initial viscosity average molecular weight of 15
Polylactic acid (poly-L-lactic acid, poly-D-lactic acid, poly-L / D) of about 10,000 to 600,000, preferably about 200,000 to 550,000
-Lactic acid), lactic acid-glycolic acid copolymer, and the like, and particularly those containing about 10 to 60% by weight of bioceramics powder are more preferably used.

The osteosynthesis device D ₁ made of the biodegradable and absorbable polymer containing the bioceramic powder as described above.
When welding the living bone using, and bioceramics powder exposed on the surface, the bioceramics powder coming exposed with the hydrolysis, conductivity formed bone tissue into the inside from the surface layer portion of the osteosynthesis device D ₁ It is the reason, improved relatively fixed force attached bone connectors D ₁ and living bone within a short time,
In addition, there is an advantage that the joint can be quickly reconstructed by replacing the bone tissue in a shorter period of time than a osteosynthesis tool containing no bioceramics powder.

Examples of the bioceramic powder include surface-bioactive calcined hydroxyapatite, bioglass-based or crystallized glass-based biological glass, non-calcined hydroxyapatite, dicalcium phosphate, tricalcium phosphate, tetracalcium phosphate, and bioabsorbable. Powders such as calcium phosphate, octacalcium phosphate, and calcite are suitable, and these may be used alone or as a mixture of two or more. In particular, non-calcined hydroxyapatite, which has a high ability to form conduction in bone tissue, is optimal.

The osteosynthesis device D ₁ may be formed by melt-forming a biodegradable and absorbable polymer and cutting the molded body, or by further uniaxially stretching the molded body and then cutting the molded body.
Alternatively, it is manufactured by further forging the formed body and then cutting. Forging molding refers to cold-press-filling a molten molded body of biodegradable and absorbable polymer into a bottomed mold and secondary molding. Device D ₁ is a compressed multiaxially oriented body in which the molecular chains of the biodegradable and absorbable polymer, its aggregation domains, clusters, crystals, and the like are oriented along many reference axes having different axial directions. Thus, the material has little strength anisotropy and has high strength against external forces and torsional forces in various directions.

The osteosynthesis device D ₁ having the above-described structure is shown in FIG.
As shown in the figure, the medullary cavity insertion pins 2, 2 on both sides of the circular block 1 are inserted into the medullary cavity 10 of the cut living bones 101, 101.
The cut bones 101 and 101 are joined by being inserted into the bones 2 and 102, respectively. Since the circular block 1 is interposed between the bones 101 and 101 and serves as a spacer, it is the same as the conventional one. When the length (thickness) of the circular block 1 in the axial direction (thickness) is the same as the cut size of the living bone, the entire length of the living bone joined to the original bone is not shortened. The total length of the living bone is substantially the same. In order that the length of the joined living bone and the length of the original living bone hardly change, a circular block 1 is used.
To prepare several types of osteosynthesis having slightly different axial lengths (thicknesses) of the osteosynthesis, and to be able to select an osteosynthesis having a circular block 1 having substantially the same length as the resected dimension of a living bone. Is desirable.

[0027] The cut living bone as described above bonded with osteosynthesis device D _1, osteosynthesis device D ₁ is absorbed into the body receives the gradually hydrolyzed from the surface in contact with body fluids in the body,
The joint is reconstructed, gradually replacing the growing bone tissue. In particular, the inclusion of bioceramic powder on the bone connectors D _1, living bone as described above and bone connectors D1
Are early bonded to increase fixation force, and also improve the replaceability with bone tissue, so that the joint can be reconstructed in a shorter time than a bone joint device not containing bioceramic powder.

FIG. 3 is a perspective view of an osteosynthesis device according to another embodiment of the present invention, and FIG. 4 is a partially enlarged cross-sectional view showing a use state of the osteosynthesis device.

The osteosynthesis device D ₂ comprising the biodegradable and bioabsorbable polymer, by cutting the outer peripheral surface of the distal end side from the middle of the medullary cavity insertion pins 2,2, toward the pin tip tapered-off of The tapered surface portion 4 and the flange-shaped step portion 5 are alternately formed, and the step portion 5 forms a surface substantially perpendicular to the axial direction. The other configuration is similar to that the osteosynthesis device D ₁ of the said, not described are denoted by the same reference numerals to the same members.

In the osteosynthesis device D ₂ , the medullary cavity 102 of the living bones 101, 101 with the medullary cavity insertion pins 2, 2 cut off while the medullary cavity 102 is being pushed and spread by the tapered surface portion 4 of the constriction. 102, the medullary cavity 102, 1
02, even if the inner diameter is slightly smaller,
Can be easily inserted to join the living bones 101, 101. When joined in this manner, as shown in FIG. 4 in an enlarged manner, the outer peripheral end of the step 5 of the medullary cavity insertion pin 2 is
2 is slightly bitten into the inner surface of the bone 2, and even if a force in the removal direction acts, the removal of the intramedullary canal insertion pin 2 is prevented, so that the joining strength of the living bones 101 and 101 is improved.

In order to effectively prevent the medullary cavity insertion pin 2 from coming out of the medullary cavity 102, the step size of the flange-shaped step portion 5 is set within a range of 0.1 to 1.5 mm, and
It is desirable that the interval between the step portions 5 is set to 0.5 to 3 mm so that the outer peripheral end of the step portion 5 is sufficiently digged into the inner surface of the medullary cavity 102.

FIG. 5 is a front view of an osteosynthesis device according to still another embodiment of the present invention. This osteosynthesis device D ₃ has a tapered outer peripheral surface over the entire length of the medullary canal insertion pins 2 and 2. The surface portion 4 and the flange-shaped step portion 5 are formed alternately and continuously. The other configuration is the same as the osteosynthesis device D ₂ above, description thereof is omitted same reference numerals are denoted for the same members.

[0033] Such osteosynthesis device D _3, since the exit from the medullary cavity of the marrow cavity insertion pins 2,2 can be more effectively prevented, there is an advantage that the bonding strength between the living bone is further improved.

[0034] Figure 6 is a front view of the osteosynthesis device according to still another embodiment of the present invention, the osteosynthesis device D ₄ is the medullary cavity insert pin 2,2 is curved at a constant radius of curvature I have. The other configuration is similar to that the osteosynthesis device D ₁ of the said, not described are denoted by the same reference numerals to the same members.

Such a bone connecting device D ₄ is used for connecting a living bone curved like a rib, and inserts the curved medullary cavity insertion pins 2 and 2 into the medullary cavity of the curved living bone. Thus, the living bone can be joined in the original curved state. The radii of curvature of the medullary cavity insertion pins 2 and 2 are set to have substantially the same radius of curvature in consideration of the radius of curvature of the curved living bone. In addition, a tapered surface portion 4 and a step portion 5 are alternately formed on the distal end side of the medullary cavity insertion pins 2 and 2 or on the outer peripheral surface over the entire length to effectively prevent the medullary cavity insertion pins 2 and 2 from coming out. Can also.

FIG. 7 is a front view of the osteosynthesis device according to still another embodiment of the present invention, the osteosynthesis device is D ₅ is coaxially one medullary canal insertion pin 2 and circular block 1 The other medullary cavity insertion pin 2 is protruded and is curved with a constant radius of curvature. The other configuration is the same as the osteosynthesis device D ₄ above, and its description is omitted with the same reference numerals to the same members.

[0037] Such osteosynthesis device D _5, by one of the living bone that has been cut is straight and the other living bone inserted into the medullary canal which is curved, is joining the living bone to its original shape It is possible. Even have the該接Gogu D _5, it may be formed over the front end side or the entire length of the medullary cavity insert pin 2,2 alternately and tapered surface portion 4 and the stepped portion 5, in that case, the medullary cavity There is an advantage that the effect of preventing the insertion pins 2 and 2 from coming off is improved.

Although the medullary cavity insertion pins of the osteosynthesis devices of each of the above embodiments are all round bar-shaped, they may be rod-shaped bodies having other polygonal cross-sections such as quadrangular and hexagonal. Further, although the medullary cavity insertion pin is provided coaxially with respect to the circular block, one of the pins may be eccentric,
Further, the size of the pins on both sides of the circular block may be changed.

[0039]

As is clear from the above description, in the bone connector of the present invention, the central circular block functions as a spacer, and the cut living bone can be bonded at intervals.
If the length of the circular block in the axial direction (thickness) is approximately equal to the cut size of the living bone, it is possible to prevent the total length of the joined living bone from being shortened. An effect is obtained that the joint can be performed so that the entire length of the later living bone and the length of the original living bone hardly change.

An osteosynthesis device having a tapered surface portion and a step portion formed alternately on the outer peripheral surface of the medullary cavity insertion pin,
The intramedullary cannula insertion pin is effectively prevented from coming out of the medullary canal, so that the joint strength is improved. The bone in which the medullary canal insertion pin is curved is suitable for cutting a curved living bone. The osteosynthesis made of is dense and strong, and the osteosynthesis containing bioceramic powder conducts the bone tissue as it is hydrolyzed in the living body and bonds with the living bone in a short time. Since the fixing force is improved and the bone tissue can be easily replaced, the joint portion can be reconstructed at an early stage.

[Brief description of the drawings]

FIG. 1 is a perspective view of an osteosynthesis device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a use state of the osteosynthesis device.

FIG. 3 is a perspective view of a osteosynthesis device according to another embodiment of the present invention.

FIG. 4 is a partially enlarged cross-sectional view showing a use state of the osteosynthesis device.

FIG. 5 is a front view of a osteosynthesis device according to still another embodiment of the present invention.

FIG. 6 is a front view of an osteosynthesis device according to still another embodiment of the present invention.

FIG. 7 is a front view of a osteosynthesis device according to still another embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a usage state of a conventional osteosynthesis pin.

FIG. 9 is an explanatory view of a conventional method for reconstructing a part of a living bone which has been cut away.

[Explanation of symbols]

D ₁ , D ₂ , D ₃ , D ₄ , D ₅ Bone connector 1 Circular block 2 Pin for insertion of medullary cavity 4 Tapered surface portion of constriction 5 Step section 101 Cut living bone 102 Medullar cavity

Claims (5)

[Claims] 1. A osteosynthesis device made of a biodegradable and absorbable polymer, comprising a pair of medullary cavity insertion pins having a diameter smaller than the diameter of the central circular block protruding from both sides in the axial direction of a central circular block. An osteosynthesis, characterized in that it is made. 2. The osteosynthesis device according to claim 1, wherein a tapered surface portion and a step portion which are tapered toward the tip of the pin are formed alternately on the outer peripheral surface of the medullary cavity insertion pin. . 3. The osteosynthesis device according to claim 1, wherein at least one of the medullary cavity insertion pins is curved. 4. The osteosynthesis device according to claim 1, wherein the osteosynthesis device is made of a forged molded product of a biodegradable and absorbable polymer. 5. The osteosynthesis device according to claim 1, further comprising a bioceramics powder.