JP2520678B2 - Surgical monofilament suture - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention comprises a surgical suture, more specifically a polycaprolactone polymer, which is supple and has sufficient strength, and is absorbed into the living body for a long period of time. The present invention relates to a surgical monofilament suture.

(Prior Art) Surgical threads for surgery are roughly classified into monofilaments and multifilaments such as twisted threads and braided threads according to their shapes.
As the material, synthetic polymers such as nylon, polyester, polypropylene, etc., non-corrosive metal wires such as stainless steel, or animal fibers such as silk thread are widely used.

Further, in recent years, high molecular weight polycaprolactone has been attracting attention for medical use, and as seen in JP-A-62-60557, a polycaprolactone polymer is used for coating a suture thread.

(Problems to be Solved by the Invention) Generally, a monofilament suture has an advantage that it has good tissue passage properties during use because of its smooth surface. Since the yarn appears as hardness, the yarn feels hard, and when the yarn is wound in multiple loops for packaging, the looped loop curl remains and it becomes difficult to handle.

On the other hand, multifilament sutures are much more flexible than monofilaments, have a low flexural modulus, and are excellent in strength against repeated bending, but on the other hand, they lack surface smoothness and are therefore treated with a surface coating. Is required. This coating process helps to adjust the number of knots safely, but if the coating agent is non-bioabsorbable, there is a risk that the coating agent separated from the thread surface will diffuse into the body as a foreign substance. Careful consideration is required.

(Means for Solving the Problems) The present invention provides a monofilament suture in which the disadvantages such as the high bending elastic modulus (Young's modulus) of the above-mentioned medical suture, particularly the monofilament suture, and lack of flexibility are improved. The polycaprolactone polymer having a relative viscosity of 2.0 to 3.2 is linearly melt-spun and stretched to obtain a monofilament suture having a predetermined thickness.

The polycaprolactone polymer is non-toxic and has a preferable property as a suture thread that it is gradually decomposed and absorbed in living tissues. Polycaprolactone polymers used for coating sutures in this type of field have a relative viscosity of 1.3 to 1.5, but in the present invention a relative viscosity of 2.0 to
It has a Young's modulus of 3.2 and is therefore a supple monofilament suture.

The elongation at break of the above-mentioned polycaprolactone monofilament suture of the present invention can be controlled by performing annealing (heat treatment) after stretching. The elongation at break is closely related to the elastic modulus of the yarn,
Generally, when the yarn is sufficiently stretched to form a yarn having a small elongation, the elastic modulus becomes high, and in the case of a yarn having a large elongation, the elastic modulus becomes low.

Polycaprolactone polymer is particularly soft among the polymers that have been used as sutures, so for example, a thread having an elongation at break of 100% or more is too supple and less elastic, and the performance as a suture decreases. On the contrary, the elongation at break
If it is less than 15%, the elongation is small, so it is necessary to get used to it by the experience to apply the force at the time of knotting, and especially in the case of a thin suture, it may be unintentionally cut off at the time of knotting. Therefore, the elongation at break of the monofilament which is easy to handle and has a high tensile strength and an appropriate flexural modulus is preferably 30 to 80%.

Also, as a bioabsorbable suture, cut good,
Polyglycolic acid, polyglycolic acid / poly L lactic acid copolymer, chitin and the like are known, but these have properties that are not suitable as an absorbable suture. For example, in Cut Good, the threads are hard and difficult to handle, and the absorbability is adjusted by using chrome, but there are variations in absorbability between products and biocompatibility is not very good. Polyglycolic acid has sufficient tensile strength and is stable with little variation in solubility, but it is difficult to make it into a monofilament suture of a commonly used thickness because the polymer is hard.
Although chitin fibers have good solubility, they swell when wet and their tensile strength decreases. However, the suture according to the present invention is soft, has a small difference in dry / wet strength, and further has a good cut property.
Dissolution rate is slower than that of sutures made of polyglycolic acid, polyglycolic acid / poly-L-lactic acid copolymer, chitin, etc., and the strength of the sutures after surgery lasts for a long time. Site, such as cardiovascular, organ transplant,
Optimal for pediatric surgery during growth.

And, the polycaprolactone suture of the present invention can be easily needled like a conventional suture such as polypropylene or nylon, and can be made into a polycaprolactone monofilament suture with a needle at one end or both ends. Various low-temperature sterilization methods that do not exceed 60 ° C., such as sterilizing agents for gas bodies and radiation sterilization using α rays, can be applied.

Further, a colored suture can be obtained by using a dye which is safe and heat stable to the human body, such as titanium white or phthalocyanine blue during melt spinning.

The thermoplastic polycaprolactone polymer used in the suture of the present invention is manufactured as follows.

That is, it can be obtained by subjecting a lactone monomer such as ε-caprolactone monomer to ring-opening addition polymerization in the presence of an initiator having an active hydrogen group and a catalyst.

The catalyst used in this reaction is an organotin compound,
Organic titanium compounds, organic halogen compounds, etc. are generally used, and the amount used is 0.1-5,000 with respect to the starting material.
ppm, preferably 10 to 100 ppm. Reaction temperature is 100-23
A temperature of 0 ° C is suitable, and it is preferable to carry out in an inert gas.

It is not preferable to set the reaction temperature to 230 ° C or higher. The depolymerization temperature of polycaprolactone is about 220-230.
This is because the reaction product is at a temperature of 0 ° C., so that if the reaction is performed at a temperature higher than this, the polymer is decomposed and the molecular weight does not increase. On the contrary, when the reaction temperature is 100 ° C or lower, the reaction rate is slow and the efficiency is poor.

This thermoplastic polycaprolactone polymer has various molecular weights (that is, relative viscosities) ranging from liquid to solid at room temperature, and is used for various purposes. The polycaprolactone polymer used has a relative viscosity of 2.0 to 3.2.

Incidentally, polycaprolactone polymers having a relative viscosity of 2.0 to 3.2 are commercially available for various applications, for example,
Object for boosting operation (JP-A-60-240692), plastic clay (JP-A-61-42679), medical cast (JP-A-58-810)
42), splint materials, face masks for radiation irradiation, and wig mold attachment (Japanese Patent Laid-Open No. 60-215018).

Specific examples of the polycaprolactone polymer having a relative viscosity of 2.0 to 3.2 include RCL-H5 and H7 manufactured by Daicel Chemical Industries, Ltd. and commercially available.

The relative viscosity is measured according to JIS standard (K-6726) at solvent: toluene, concentration: 1%, temperature: 25 ± 0.05 ° C.

(Function) The polycaprolactone monofilament suture obtained by melt-spinning and stretching a polycaprolactone polymer having a relative viscosity of 2.0 to 3.2 is a monofilament, but has a small Young's modulus and further has a linear tensile strength and a knot strength. Are better. Therefore, it exerts a favorable performance as a medical suture thread, fastens the sutured part for a long time, and is gradually absorbed into the living body during that time, until the part that takes time to heal the biological tissue is surely healed. Sustaining and retaining action is sustained.

(Example) Example 1 A resin having a relative viscosity of 2.34 (polycaprolactone polymer manufactured by Daicel Chemical Industries, Ltd .: PCL-H7) was used at a nozzle temperature of 220 ° C.
Was melt-spun, and immediately after spinning, it was immediately cooled with cooling water at 25 ° C. for 5 seconds and then wound at a speed of 6 m / min. After that, the first
In the second stage, it was stretched 5.0 times in the air at 25 ° C, and in the second stage it was stretched 1.6 times in warm water at 52 ° C to give a thickness of 0.246.
mm polycaprolactone monofilament sutures were obtained.

Example 2 The polycaprolactone monofilament suture obtained in the above Example 1 was treated by dry heat at 53 ° C. for about 20 minutes in a tension-free state for annealing to obtain an annealed polycaprolactone monofilament suture. .

Comparative Example 1 A resin having a relative viscosity of 1.58 (polycaprolactone polymer manufactured by Daicel Chemical Industries, Ltd .: PCL-H4) was used at a nozzle temperature of 100 ° C.
Was melt-spun, immediately after spinning, it was immediately cooled with cooling water at 25 ° C. for 5 seconds and then wound at a speed of 4 m / min. After 25
It was drawn 7.8 times in air at ℃ to obtain a polycaprolactone monofilament suture having a thickness of 0.246 mm.

In addition, commercially available polypropylene monofilament suture (thickness 0.231 mm) and nylon monofilament suture (thickness 0.236 mm) were used as Comparative Example 2 and Comparative Example 3, respectively.

The linear tensile strength, elongation at break, knot strength and Young's modulus of Examples 1 and 2 and Comparative Examples 1 to 3 were measured. The results are shown in Table 1.

Example 3 The polycaprolactone polymer used in Example 1 was processed in the same manner as in Example 1 to prepare a suture thread corresponding to 4-0 (diameter 0.195 mm).
Implanted in the rabbit spine, 2 months, 4 months, 6 months, 8 months
After 10 months, 10 months and 12 months, it was taken out to form a sample thread of about 20 cm, and the respective linear tensile strengths, residual tensile strengths and elongations at break for the sample thread before embedding were measured. Table 2 shows the results.

Example 4 The suture of Example 3 was dipped in physiological saline at 37 ° C. for 2
The straight line tensile strength, residual tensile strength and elongation at break of each sample yarn taken out after 4 months, 4 months, 6 months, 8 months, 10 months and 12 months were measured. Table 2 shows the results.

(Effects of the invention) As described in detail in the above, the polycaprolactone monofilament suture according to the present invention is extremely supple despite being a monofilament, and thus is easy to handle and further has a dissolution rate in vivo. Since it has a slow and long-term suture holding tension, it is suitable for suturing a site where tissue healing takes longer than usual, and exerts a remarkable effect as a surgical suture of this type of site.

Claims (2)

(57) [Claims] 1. A drawn surgical monofilament suture comprising a polycaprolactone polymer having a relative viscosity of 2.0 to 3.2. 2. The surgical monofilament suture according to claim 1, wherein a needle is attached to one end or both ends of the suture.