GB2336783A

GB2336783A - Surgical needle

Info

Publication number: GB2336783A
Application number: GB9910084A
Authority: GB
Inventors: Shouichi Fukuda; Masaaki Matsutani; Kanji Matsutani
Original assignee: Mani Inc
Current assignee: Mani Inc
Priority date: 1998-05-01
Filing date: 1999-04-30
Publication date: 1999-11-03
Anticipated expiration: 2019-04-30
Also published as: GB2336783B; DE19919889A1; JP4078467B2; DE19919889B4; GB9910084D0; JPH11309152A

Abstract

A surgical needle having a tip or needle point section A at one end thereof, a base section C at the other end, and a shank section B which extends between the tip and base sections, said, needle comprising stainless steel containing chromium in an amount of about 16 to 18 weight %, nickel in an amount of about 7 to 9 weight %, titanium in an amount of about 0.003 to 0.3 weight %, copper in an amount of about 0.003 to 0.4 weight %, molybdenum in an amount of about 0.6 to 0.8 weight %, and silicon in an amount of about 0.1 to 1.7 weight %. The tip and shank sections contain precipitation particles of titanium, copper and molybdenum. Said tip and shank sections preferably include an elongated crystal structure extending in a longitudinal direction of said needle.

Description

2336783

SURGICAL NEEDLE Ba-ckaround of the Invention (1) Field of the invention

The present invention relates to a surgical needle.

(2) Prior Art

Generally, surgical needles have a tip or needle point section at one end thereof, a base section at the other end, and a shank section extending between the tip and base sections. such surgical needles must have, in addition to rust preventive property, such properties as sharpness of the tip or needle point section, high bending strength, high anti-breaking property, i.e., resistance to breaking, etc. on the shank section of the needles.

In the past, as surgical needles made of stainless steel, the fol.lowing products have been known: a surgical needle using martensitic stainless steel which can be quenched such as 13cr stainless steel or the like, or a surgical needle using austenitic stainless steel which can not be quenched such as SUS302 (japan Industrial Standard Code) or the like.

The surgical.needle made of martensitic stainless steel can be manufactured by processing and fabricating the raw material to have adequate'softness and by quenching and hardening it in final stage. Because it is processed by quenching, it is difficult to produce a product with 1 uniform quality.

on the other hand, in case of the surgical needle made of the austenitic stainless steel as descri.bed in Japanese Patent Publication (KOKOKU) NO. 4-67978, tip and shank sections of the needle are produced by mechanical processing such as wire drawing or press working process to have long crystal structure, i.e., fibrous structure, extending in a longitudinal direction of the needle. By this manufacturing procedure, it is possible to have higher strength through hardening process. Also, a base section of the needle where surgical thread is to be securely engaged may be produced by solution treatment to have crystal structure with no specific orientation, and this makes it possible to maintain good workability or fabricability and easiness to engage a thread on the base section of the needle".

However, when conventional type austenitic stainless steel, e.g. sus302, Sus304, sus63611, etc. are used as raw material, it is difficult to produce a needle by work hardening based on mechanical processing to produce a needle which has high hardness and strength on the tip and shank sections of the needle. Also, even when the austenitic stainless steel is processed by heat treatment, i.e., tempering, for precipitation hardening of composition elements, it is difficult to accomplish sufficient 2 precipitation hardening. Therefore, the surgical needle made of austenitic stainless steel as used in the past has such limitation that it cannot provide sufficient properties such as sharpness, bending strength, anti- breaking property, i.e., resistance to breaking, etc. on the tip and shank sections of the needle-.

ACCordingly, it is an object of the present invention to provide a surgical needle, which has sufficient properties such as sharpness, bending strength, anti- breaking property, i.e., resistance to breaking, etc. on tip and shank sections of the.needle, in addition to rust preventive property.

Disclosure of the InventiQn

To overcome the above problems, the surgical needle according to the present invention has tip and base sections at opposite ends thereof and shank section extending between the tip and base sections and consists of stainless steel containing chromium in an amount of about 16 to 18"weight %, nickel in an amount of about 7 to 9 weight titanium in an amount of about 0.003 to 0.3 weight copper in an amount of about 0.003 to 0.4 weight molybdenum in an amount of about 0.6 to 0.8 weight and silicon in an amount of about 0.1 to 1.7 weight %, whereby the tip and shank sections contain precipitation particles of titanium, copper and molybdenum.

3 The stainless steel having the above described composition has chromium content and nickel content approximately equal to chromium content and nickel content in sus302, sus304, etc. and thus has property substantially equal to that of austenitic stainless steel. Therefore, the surgical needle according to the invention has rust preventive property, and it is possible to form workhardened and str. ain-induced martensite in the needle.

on the other hand, the stainless steel having the above described composition is entirely different from the conventional type austenitic stainless steel such as SUS302 in the features that it contains titanium.in an amount of about 0.003 to 0.3 weight %, copper in an amount of about 0.003 to 0.4 weight %, and molybdenum in an amount of about 0.6 to 0.8 weight The surgical needle according-to the present invention contains precipitation particles of these elements in the tip and shank sections. As' a result, it is possible to increase hardness and strength, in particular bending strength, due to precipitation hardening of these elements and also to improve ductility or cyclic bending strength.

As the elements to be precipitated to the tip and shank sections, it is preferable to use titanium, copper, and molybdenum. when the other elements are precipitated, the product may become too brittle on the contrary, and 4- sufficient bending-strength and ductility'cannot be attained. Also, when the contents of titanium, copper or molybdenum are lower than the numerical values in the range as given above, it is not possible to obtain an effect to increase the strength by precipitation hardening of these elements. on the other hand, if the content is higher than the above range, the product becomes too brittle.

Preferably, the stainless steel for the surgical needle according to the present invention contains silicon in an amount of about 1.1 to 1.7 weight %. with this construction, resilient property of the tip and shank sections of the surgical needle can be improved, and bending strength and ductility of the surgical needle can be further improved.

is Preferably, the surgical needle as described above has long crystal structure extending in longitudinal direction of the needle at the tip and.shank sections. with this construction, hardness and strength of the tip and shank sections can be further increased.

more preferably, the surgical needle as described above has crystal structure with no specific orientation at the base section. Such construction makes it possible to have high workability and easiness to engage a suture thread on the base section of the needle.

It is also provided, according to the present invention, a method for manufacturing a surgical needle having tip and base sections at opposite ends thereof and a shank section extending between the tip and base sections. The method comprises the steps of:

shaping a needle material in shape of a surgical needle by cold mechanical processing, the needle material being made of stainless steel containing chromium in an amount of about 16 to 18 weight %, nickel in an amount of about 7 to 9 weight %, titanium in an amount of about 0.003 to 0.3 weight %, copper in an amount of about 0.6 to 0.8 weight and silicon in an amount of about 0.1 to 1.7 weight %; and conducting aging heat treatment to the needle material having the, shape of surgical needle.

By the method of the present invention as described above, it is possible to-perform work hardening by cold mechanical processing of the needle material, and to produce strain-induced martensitic structure in the needle material. Also, by aging heat treatment, long-term deterioration of the metal structure can be prevented,. and it is possible to effectively precipitate titanium, copper and molybdenum in the needle material. As a result, hardness and strength, in particular bending strength, of the surgical needle can be extensively-increased.

Preferably, the silicon content of the stainless steel as described above is about 1.1 to 1.7 weight %.

6 more preferably, the cold mechanical processing as described above is performed at temperature range from normal temperature to about 30TC. AS the cold mechanical working, working means such as press working, grinding, bending, etc. may be adopted. The surgical needle may be designed in the form of round needle having a rounded point, blunt needle having a blunt point, or angular needle having an edge at the tip section. Also, bending may be performed on the tip and shank before or after or at the same time as it is processed by press working or grinding.

Preferably, the aging heat treatment is performed at temperature of about 4009C to SOTC, or more preferably at temperature of 420X to 4809C, for about 1 to 4 hours.- In so doing, long-term-deterioration of the product can be prevented while maintaining internal long crystal structure, and precipitation particles of titanium, copper an d molybdenum can be effectively formed in the tip and shank sections of the needle material. Aging heat treatment as described above may be 20 performed i,n vacuum condition (e.g. 10-1 to 10 Pa) or in the atmosphere of the air, nitrogen, etc. or in salt bath. In the method of the present invention, aging heat treatment may be performed after polishing the needle surface, while it is preferable to carry out polishing of the needle surface after the aging heat treatment. By 7 performing polishing of the needle surface after aging heat treatment, oxidized layer on the needle surface can be removed. Also, oxidized layer and microcracks on the needle surface can be removed by polishing of the needle surface, and this reduces stress concentration and improves ducti lity. Further, for polishing of the needle surface, chemical polishing, electrolytic polishing, buffing, etc. may be applied.

more preferably, after the aging heat treatment or surface polishi.ng as described above, heating solution treatment is conducted to the base section of the needle material. In so doing, it is possible to easily fabricate and form a thread engaging portion such as needle eye to engage with thread, caulking eye, caulking groove, or the 1 i ke at. the base secti on of the needl e materi al. AI so, i t As possible to increase thread engaging property or tensile strength of suture thread engaged or attached on the base section of the needle. Brief ExplanatiQn of the,Drawing-s 20 Figure 1 is a perspective view of an eyeless suture needle for surgical use s"howing an embodiment of the present invention; and Figure 2 is a graphic representation of the results of bending moment test showing the effects of the product with the arrangement according to the present invention.

1 S Preferred Embodiments of the Invention In the following, description will be given on the preferred embodiment of the present invention referring to the attached drawings.

Fig. 1 shows.an embodiment of the present invention when the invention is applied to a suture needle of eyeless type for surgical operation. Referring to the figure, a suture needle 1 has a tip or needle point section A at one end-thereof, a base section c at-the other end thereof, and a shank section B which extends between the tip section A and the base section C. The suture needle 1 is made from a needle material which consists of stainless steel.

Table 1 comparatively summarizes chemical.components of a needle material used for the above suture needle 1 and themical components of SUS302, which is a typical austenitic stainless steel as commonly used in the past.

Q Tab] e 1 Content (weight-%) Chemical components material alloy sus302 carbon 0.09 max. 0.15 max.

silicon 1.1 - 1.7 1.0 max.

manganese 0.1 - 1.8 2.0 max.

Phosphorus 0.025 max. 0.045 max.

sulfur 0.02 max. 0.03 max.

chromium 17.0 - 18.0 17.00 19.00 Nickel 7.0 - 8.0 8.00 10.00 Titanium 0.03 - 0.3 copper 0.03 - 0.4 molybdenum 0.6 - 0.8 cobalt 0.4 max.

Iron Remainder Remainder AS it is evident-froM Table 1, in the needle material of the present embodiment, the contents of chromium and nickel are approximately equal to those of chromium and nickel in SUS302, and it has the property of austenitic stainless steel. on the other hand, the needle material of the present embodiment is different from the austenitic stainless steel as commonly used in the past in such features that the needle material contains titanium in an amount of 0.1 to 0.3 weight %, copper in an amount of 0.1 to 0.3 weight %, and molybdenum in an amount of 0.6 to 0.8 weight %.

is The needle material having the above chemical components is manufactured, for example, first by melting each of the components according to vacuum induction melting method. Next, it is turned to linear bar stock by hot working. Then, it is turned to wire rod by cold wire drawing process. By this cold wire drawing process, internal portion of the wire rod is turned to have long crystal structure extending in longitudinal direction, and strain-induced martensitic structure is produced inside the wire rod. Then, the wire rod is cut to the desired length, and after performing cold mechanical working such as press working, grinding, bending, etc., it is turned to a needle material with contour shape as illustrated in Fig. 1. In this stage, the needle material has a tip section A, a base section C, and a shank section B. is Thereafter, the needle material is processed by aging heat treatment performed at about 425't for one hour under vacuum condition. After cooling down by forced air-cooling, chemical polishing is performed on the needle material. Further, heating solution treatment is performed on the base section of the needle material at temperature of about 8OTC.and its internal portion is turned to crystal structure without specific orientation. Then, thread caulking eye lais formed at the end of the needle base, and a -suture needle 1 as shown in Fig. 1 is prepared.

To confirm the effect of the product of the present 11 invention with the arrangement as described above, bending moment was determined on a wire rod (Example 1 manufactured by the cold wire drawing process and the aging h-eat treatment as-described above using a material alloy having the chemical components shown in Table 1 and on a wire rod (conventional product) manufactured by cold mechanical working similar to the above, and then by aging treatment at 300C to 4009C for 2 to 3 minutes using SUS302. AS shown in Fig. 2, it was confirmed that the wire rod piece of Example 1 showed bending moment higher than that of the conventional product to the bending at an angle of about 15 degrees or higher. in particular, to the bending of about 30 degrees or higher, it was confirmed th,at the wire rod of the Example 1 showed bending moment about 20% higher than that of the conventional product.

Also, ductility test (a test to hold both ends of a wire rod, to repeatedly bend it at an angle of about 90 degrees at the center and to return to the initial condition, and to count number of bendings until the wire rod is ruptured) was performed on the wire rod (Example 1) having the chemical components shown in Table 1 and the wire rod (conventional product) made of sus302. The - results were as shown in Table 2. As the conventional product, only the product produced by wire drawing process was used as a test piece. As the wi re rod of Example 1, a 1 - test piece produced by wire drawing process only, a test piece produced by aging heat treatment after wire drawing process, and a test piece produced by chemical polishing after aging treatment were used as test pieces. Each of 5 the test pieces is a wire rod piece having a diameter of 0.2 mm in actual size. The test was performed on 10 pieces each per sample. In the method to determine ductility, the number of bendings was counted one by one when the test Piece was bent from straightly stretched condition to a condition bent at an angle of 90 degrees and when it was returned to the initial straightly stretched condition from the condition bent at 90 degrees. For the values under decimal point, the angle measured at the time of rupture was converted and used.

Tab] e 2 conventiona-f- Example 1 Produc t wire drawing wire drawing Aging heat chemical polishing treatment No- Number No. Number No. Number No. Num er of. of of of bendi U_ bending bending bending 1 10.1 1 9.5 1 11.5 1 13.5 2 11.2 2 9.5 2 13.0 2 13.8 3 9.5 3 13.5 3 15.0 3 13.2 4 9.5 4 13.5 4 16.0 4 13.2 10.5 5 13.5 5 11.0 5 17.5 6 11.2 6 11.2 6 13.0 6 12.5 7 10.2 7 12.2 7 11.2 7 12.8 8 9.5 8 13.5 8 17.5 8 12.3 9 10.5 9 10.5 9 15.5 9 15.8 9.5 10 9.8 10 11.3 10 12.5 Average 10.17 Average 11.67 Average 13.4 Average 13.71 maximum 13.5 maximum 13.5 maximum 17.5 maximum 17.5 minimum 9.5 minimum 9.5 minimum 11.0 minimum 12.5 AS it is evident from Table 2, it-was confirmed that,- in case only wire drawing was performed, ductility was by about 15% higher in average in the wire rod piece of Example 1 thanin the conventional product. AISO, in case aging treatment was performed, ductility was higher by about 1% in average in the wire rod piece of Example 1 than the product produced only by wire drawing. it was also confirmed that ductility was further improved (by about 2 to 3%) when chemical polishing was performed.

1 l- in the wire rod piece in Example 1, silicon content was about to 1.1 to 1.7 weight compared with the case where the content was not more than 1.0 weight %, it was confirmed that spring property was improved, and bending strength and ductility were further improved.

AS it is clearly seen in the above explanation, the surgical needle according to the present invention has property of austenitic stainless steel. Thus, it has-rust preventive property, and hardness and strength are improved due to the formation of work-hardened and strain-induced martensite. moreover, the surgical needle of the present invention contains titanium in an amount of about 0.003 to 0.3 weight %, copper in an amount of about 0.003 to 0.4 weight %, and molybdenum in an amount of about 0.6 to 0.8 weight % and has precipitation particles of these elements in the tip or needle point section and the shank section. As a result, hardness and strength, in particular bending strength, are improved due to precipitation hardening of these elements, and ductility is also improved. Therefore, it is possible to provide a surgical needle, which has, in addition to rust preventive property, high sharpness, high bending strength, anti-breaking property, i.e., resistance to breaking, etc. on the needle point and the needle shank continuous to the needle point.

Further, according to the method of the present is invention, it becomes possible to provide surgical needles having a property as mentioned above. - 16

Claims

WHAT IS CLAIMED IS:

A surgical needle having tip and ba-se sections at opposite ends thereof, respectively, and a shank section extending between said tip and base sections, wherein said surgical needle consists of stainless steel containing chromium in an amount of about 16 to 18 weight %, nickel in an amount of about 1 to 9 weight %, titanium in an amount of about 0.003 to 0.3 weight %, copper in an amount of about 0.003 to 0.4 weight %, molybdenum in an amount of about 0.6 to 0.8 weight %, and silicon in an amount of about 0.1 to 1.7 weight %, and said tip and shank sections, contain precipitation particles of titanium, copper and molybdenum.
2. The surgical needle according to claim 1 wherein the silicon content of said stainless steel is about 1A to 1.7 weight
3. The surgical needle.according to claim 1 wherein said tip and shank sections include elongated crystal structure extending in a longitudinal direction of said needle, while said base section includes crystal structure with no specific orientation.
4. The surgical needle according to claim 1 wherein said base section has one of a needle eye, caulking hole or caulking groove for securing therein a suture thread. 25
5. A method for manufacturing a surgical needle 11 7 having tip and base sections at opposite ends thereof, respectively, and a shank section extending between the tip and base sections, said method comprising the steps of:

shaping a needle material in shape of a surgical needle by means of cold mechanical processing, said needle material having tip and base sections at opposite ends thereof, respectively, and a shank section' which extends between said tip and base sections and being made of stainless steel containing chromium in an amount of about 1016 to 18 weight %, nickel in an amount of about 7 to 9 weight %, titanium in an amount of about 0.003 to 0.3 weight copper in an amount of about 0.003 to 0.4 weight molybdenum in an amount of about 0.6 to 0.8 weight and silicon in an amount of about 0.1 to 1.7 weight %; and conducting aging heat treatment to said needle material having the shape of surgical needle to generate precipitation particles of titanium, copper and molybdenum in said tip and shank sections.
6. The surgical needle according to claim 5 wherein the silicon content of said stainless steel is about 1.1 to 1.7 weight %.
7. 'The method according to claim 5 wherein said cold mechanical processing is performed at temperature of about 4000C to SOTC for about 1 to 4 hours.

is
8. The method according to claim 5 wherein said cold mechanical processing is performed at temperature of about 4209C to 4809C for about 1 to 4 hours.
9. The method according to claim 5 further comprising the step of conducting surface polishing treatment to said needle to which said aging heat treatment has been conducted.
10. The method according to claim 9 further comprising the step of conducting heating solution treatment to said base section of said needle to which said surface polishing treatment has been conducted.
11. The method according to claim 5 further comprising the step of conducting heating solution treatment to said base section of said needle to which said aging heat treatment has been conducted.

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