JPH11137564A - Bone-setting utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the productivity, and improve the yield by constituting a bone-setting utensil of an article having a head part, which is formed by pressing. SOLUTION: This bone-setting utensil is constituted of an article having a head part 14, which is formed by pressing. On a swage punch 5 of a press device 3, a long-sized, approx. trapezoidal indent 8 is provided, and on a swage punch 6, a trapezoidal indent 9 which is shorter than the indent 8 and has a larger diameter is provided, and on a swage punch 7, an indent 10 having the same size and shape as a desired screw head, is provided, and on a die 4, a cylindrical part 11 where a cylindrical forming article 1 to be formed is housed, and a cylindrical part 12 of a larger diameter where the swage punches are inserted, and by which a screw head part is formed, are constituted. A long-sized cylindrical forming article 1 of an in-vivo degradable-absorbable resin is inserted in the cylindrical part of a smaller diameter, and after the end part is fixed by a stopper 13, the tip end of the forming article 1 is pressed by the heated swage punch 5, and the forming article 1 is removed after being cooled. In addition, by operating the swage punches 6, 7, a cooling is performed, and a screw head part 14 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an osteosynthesis tool used for joining and fixing bones in the treatment of broken or missing bones, and more particularly to a head structure.

[0002]

2. Description of the Related Art An osteosynthesis made of polylactic acid, polyglycolic acid, a copolymer of polylactic acid and polyglycolic acid, which is a biodegradable and absorbable polymer, must be removed after surgery. Because of its lack, it is being put to practical use as a new material that replaces metals, ceramics, etc. Such fittings are:
The melt molded product is processed into various shapes such as screws, nails, pins, screws, plates, bolts, rivets, staples and the like, and the processing is generally performed by cutting.

[0003]

However, according to such a method, cutting requires a high level of technology and time, and
In particular, when such a molded product has been subjected to a stretching treatment in order to improve bending strength, tensile strength, etc., the formed fibrils are cut by cutting to reduce the strength or increase the decomposition rate. occured. In addition, in the case of the above-mentioned osteosynthesis, the diameter of the head is generally larger than that of the body, and a large amount of cutting chips is generated because the body is formed by sequentially cutting a molded product having the same diameter as the head. Also occurred. The present invention is to solve the conventional drawbacks, and to provide a novel technique that improves productivity and improves yield.

[0004]

That is, the present invention has a head obtained by press molding,
Facing direction, that is, having a head obtained by pressing from the axial direction, being a head obtained by pressing with an upsetting punch, pressing with an upsetting punch having a groove for screwing, and screwing That the groove is formed, that the molded article is made of biodegradable and absorbable polymer, that it is an elongated molded article, that the osteosynthesis tool is a screw, nail, pin, screw,
An osteosynthesis device characterized in that it is either a plate, bolt, rivet, staple, or the like.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The biodegradable and absorbable polymer used in the present invention includes the above-mentioned polylactic acid (L-form, D-form, blend of L-form and D-form, copolymer, stereocomplex, etc.) ), Polyglycolic acid, and copolymers of polylactic acid and polyglycolic acid. Examples thereof include those having a molecular weight of about tens of thousands to one million, or those obtained by adding bioceramics such as hydroxyapatite thereto. It is appropriately selected, but is not limited to this as long as it is a thermoplastic biodegradable and absorbable polymer. Such a polymer material is obtained by melting and extruding a polymer chip into an arbitrary shape such as a rod (rod) shape, a band (plate) shape, or pressing to form a molded product.
Alternatively, this can be further added to Japanese Patent Publication No. 3-639 by the present applicant.
Stretching in the long axis direction under heating as disclosed in No. 01,
Alternatively, pressure is applied through a heat medium as disclosed in JP-A-5-168647, extruded from a nozzle and stretched (hydrostatic extrusion), and a plurality of rotations are performed as disclosed in Japanese Patent Application No. 8-116922. Appropriately selected from among those rolled by passing between planetary inclined rolls under heating and the like are used, but other methods can be used as long as the molecular orientation and the strength can be improved. It does not matter. The molded article constituted as described above constitutes its head by a method exemplified below.

[0006]

Embodiment 1 FIG. 1 illustrates a molding device forming a head portion of a screw as an example. The figures (A) to (C)
The screw head having the shape shown in FIGS. 2A to 2C is formed by the procedure shown in FIG. The screw head forming device includes a press device 3 provided with three upsetting punches 5, 6, and 7 fixed thereto, and a mold 4 for accommodating a formed product. The long, substantially trapezoidal depression 8 is
The upsetting punch 6 is provided with a trapezoidal recess 9 having a shorter diameter and a larger diameter, and the third upsetting punch 7 is provided with a recess 10 having a shape equal to a desired screw head size and shape. ing. On the other hand, the mold 4 accommodates the cylindrical molded product 1 to be molded, and a cylindrical portion 11 having substantially the same diameter as this, and a large-diameter for inserting the upsetting punch and molding the screw head. A cylindrical portion 12 is configured. In this configuration, first, as shown in FIG. 1A, a long molded product 1 formed by molding a biodegradable and absorbable resin into a cylindrical shape is inserted into a small-diameter cylindrical portion 11, and an end is formed by a stopper 13. After fixing the part,
The heated first upsetting punch 5 is actuated to pressurize the tip of the molded article 1, that is, pressurize for a certain period of time from the direction facing the axis of the molded article, cool, remove, and remove the first. Pressure (press) processing. Further, FIG.
The second and third upsetting punches 6 and 7 heated in the order shown in (C) are operated and cooled to finally form a desired screw head. The formed screw head is shown in FIG.
FIG. 2C is deformed in the order shown in FIG.
1A of FIG. 1B by the process of FIG.
The state changes as shown in FIG. 2C by the step (C). In this example, the step (C) in FIG. 1 is finalized, whereby the screw head 14 having the size and shape as shown in FIG.
Is formed. In FIG. 2C, reference numeral 2 denotes a body portion, for example, the portion is pressed by a mold having a thread groove, or is cut by a lathe or the like to form a thread groove. The processing of the body part, that is, the configuration of the screw groove may be performed after the above-described screw head is formed or may be performed in a process preceding it. Further, the shape and configuration of the body portion 2 may be a screw, a rivet, a nail having a sharpened tip, or a pin having a non-slip groove, as it is without forming a screw groove. Optional, and also the number of upsetting punches, the shape of the depressions,
It is also optional to form a screwing groove for screwing in a size, or + or-corresponding to the tip of the driver, such as a square shape. For such screwed grooves, for example,
This is made possible by forming the convex portions that sign +,-, etc. in the depressions of the upsetting punch, and the screwing grooves can be simultaneously formed by the above-mentioned press working. In the above-mentioned molding, the pressing conditions and means are arbitrary, but at least a glass transition point or higher and a melting point or lower of the molded product in order to cause plastic deformation in the molded product, upset punch, or mold. In addition to the above, it is desired to appropriately provide a cooling step in order to fix the shape. In the above-described example, the stopper 13 is provided at the time of pressing. However, when the length of the molded product 1 reaches the lower end and is in contact with a pedestal or the like, or the outer diameter of the molded product and the cylindrical portion If the inner diameters of 11 are almost equal, no stopper is required. Further, for example, when the diameter between the head and the body becomes small as a result of processing, the mold 4 is configured to be divided so that the workpiece can be easily taken out.

[0007]

According to the present invention, since the head can be constructed very simply as described above, it is easy to manufacture, suitable for mass production, and does not require any specific technology such as cutting. Therefore, the quality is uniform and no loss is caused by cutting. Therefore, in addition to screws, nails, screws, pins, plate bolts, etc., any shape,
Widely applicable to any size head configuration. The molded article used for this purpose may be stretched or unstretched, but is preferably stretched because of its excellent strength. In particular, when a stretched molded product is used as a raw material, the fibril is not cut due to cutting, and thus has excellent properties of initial strength and strength retention.

[Brief description of the drawings]

FIG. 1 is a side view illustrating a manufacturing process of a screw head according to the present invention.

FIG. 2 is a side view showing a change in the shape of a screw head formed in each step of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molded product 2 Body part 3 Press device 4 Die 5 Upsetting punch 6 Upsetting punch 7 Upsetting punch 8 Depression 9 Depression 10 Depression 11 Cylindrical part 13 Stopper 14 Screw head

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takahiro Yoshioka, 1st Ikura Shinmachi Ishiburo, Ayabe-shi, Kyoto Gunze Co., Ltd. Kyoto Research Institute (72) Inventor Hajime Takeuchi, 1st Ikurashinmachi Ishiba, Ayabe-shi, Kyoto Gunze Inside the Kyoto Research Institute Co., Ltd. (72) Inventor Toru Yamamoto 1 at 38, Nishibaba, Aonocho, Ayabe City, Kyoto Medical Center (72) Inventor Yasuyuki Kishida, 38 at 38, Nishibaba, Aonocho, Ayabe City, Kyoto Medical Inside the Materials Center (72) Inventor Tohru Arima 38 Medical Devices Center, 38, Nishibaba, Aono-cho, Ayabe-shi, Kyoto

Claims (7)

[Claims] 1. An osteosynthesis device having a pressed head. 2. The osteosynthesis device according to claim 1, wherein the osteosynthesis device has a head formed by pressing from a direction facing the axis of the molded product. 3. The osteosynthesis device according to claim 2, wherein the head is obtained by pressing with an upsetting punch. 4. The osteosynthesis device according to claim 3, wherein the screwing groove is formed by pressing with an upsetting punch having a groove for screwing. 5. The osteosynthesis device according to claim 2, wherein the molded product is a biodegradable and absorbable polymer. 6. The osteosynthesis device according to claim 5, which is an elongated molded product. 7. The osteosynthesis device according to claim 1, wherein the osteosynthesis device is one of a screw, a nail, a pin, a screw, a plate, a bolt, a rivet, a staple, or the like.