What Is a Nylon Suture?

Medical sutures refer to special medical threads used for ligation and hemostasis, suture hemostasis, and tissue suture in surgery, and are divided into absorbable sutures and non-absorbable sutures.

Chinese name: Medical suture
Foreign name: Surgical Suture
Medical device classification: Passive surgical instrument

Primary product category: Surgical instruments-kiss (sewing) instruments and materials
Management category:: Absorbable sutures belong to Class III medical devices, non-absorbable sutures belong to Class II medical devices

Development history of medical sutures

1. Medical Sutures 1. World History

The earliest records of surgical sutures date back to ancient Egypt in 3000 BC, and the oldest known sutures are on mummy in 1100 BC. The first detailed written account of suture wounds and the use of suture materials came from Su Shi Ruta, a saint and physician in India from 500 BC. Hippocrates, the "father of medicine" in Greece, and later Olus Cornelius Celsus in Rome described the basic suture technique. The first description of intestinal sutures was the 2nd-century Roman doctor Galen, and some believed that it was the 10th-century Andalusian surgeon Dhalawi. According to records, once the strings of the Dhahrawirut were swallowed by a monkey, he discovered that the gut was absorbable. Since then, manufacture of medical sheep gut. ^[1]

Joseph Lister introduced a huge change in suture technology, and he advocated routine disinfection of all sutures. In the 1860s, he first tried to sterilize "Carbonic Acid Sheep Gut", and twenty years later he sterilized Chromic Sheep Gut. In 1906, a sterile sheep gut was treated with iodine.

The next big leap took place in the 20th century. With the development of the chemical industry, the first synthetic thread was made in the 1930s, and many absorptive and non-absorptive synthetic threads were developed rapidly. The first synthetic thread was made of polyvinyl alcohol in 1931. Polyester threads were developed in the 1950s, and radiation sterilization of sheep gut threads and polyester was later developed. Polyglycolic acid was discovered in the 1960s and used in the manufacture of sutures in the 1970s. Today, most sutures are made from polymer fibers. Of the ancient materials, only silk and gut were still used, but not commonly used. In recent years, magnesium alloy has attracted more and more attention as a degradable medical material. With its characteristics of easy corrosion in the human environment, it can be gradually degraded in the body until it is eventually absorbed and achieve clinical application purposes. Therefore, it is more suitable for surgical sutures. [2].

2. Medical sutures 2. History of China

China has a long history of medicine and has created many feasible surgical methods and materials. On the basis of inheriting and developing the ancients' experience, doctors have further developed and improved surgical methods and application equipment such as incision and drainage, anesthesia, debridement and suture, amputation, intestinal anastomosis, rabbit lip repair, etc., and have made in the history of human surgery huge contribution. ^[2]

Debridement and suture is one of the important inventions in Chinese medical history, and it is widely used in open injuries of various parts of the human body. In 1973, in the Western Han cultural relic "Fifty-two Diseases" unearthed at the Han Tomb No. 3 in Mawangdui, Changsha, Hunan, there was a record of using wine to clean up the wounds. If you see both ends, you can quickly continue. First use needles to continue the intestine, then take the chicken blood and smear it. Do not let the air vent, that is, push it. But those who have sore should be born with silk threads, absolutely Its blood. "This is the earliest recorded anastomosis operation in the world.

In the Sui and Tang dynasties, doctors in our country made further improvements and improvements to the materials for suture wounds. The most important invention is the use of mulberry suture to suturing the intestine and the skin, which is widely used in clinical practice and has achieved good healing results.

The so-called mulberry thread is a thin fiber thread formed by removing the outer skin of mulberry tree roots and exposing the soft long fiber layer through hammer processing. The mulberry thread is not only simple to make, convenient to apply, but not easy to break, but also has a therapeutic effect of clearing heat and detoxifying and promoting wound healing.

And in Japan's earliest existing traditional Chinese medicine health treatment classics "Yin Xin Fang" has recorded "if the intestine has been broken, suture with mulberry thin thread, hot chicken blood smeared, it is ordered to enter." Geng Jianting, a well-known modern otolaryngologist and medical historian in China, has collected all his life in Geng Jianting's Commentary on the five senses. It is recorded that the "mulberry seam trauma method" has been used until Western medicine came to China before being replaced by other methods.

Medical suture suture characteristics

1. Versatile, suture material suitable for any surgery.

2. No electrolysis, no surface tension, no allergy and no carcinogenicity.

3. Sterility, slight tissue reaction, not conducive to bacterial growth.

4. Easy to operate, strong knots and proper tensile strength. ^[3]

Medical suture classification

1. Medical sutures 1. absorbable sutures

Absorbable sutures are divided into: sheep intestine thread, chemical synthesis thread (PGA), and pure natural collagen suture thread according to different materials and absorption levels. They degrade and absorb in the body, avoiding the pain caused to the patient by the second operation, and can choose sutures with different degradation time according to the actual operation needs. ^[3]

Type of suture	Silk thread (generation)	Gut (second generation)		Synthetic absorbable suture (PGA) (three generations)	Pure natural collagen suture (Four generations)
Type of suture	Silk thread (generation)	Common gut	Chrome bowel	Synthetic absorbable suture (PGA) (three generations)	Pure natural collagen suture (Four generations)
Raw materials	Cotton fabric or polypropylene, polyester, etc.	Sheep casings for healthy animals	Sheep casings for treated healthy animals	Polymerization of artificial metabolites (glycolic acid, lactic acid)	Special animal tendon tissue
strength	high	low	low	Well above the gut	Higher than synthetic absorbable sutures
Body strength Holding time	Non-absorptive, can be maintained until the wound is fully healed	7-10 days disappeared, the patient's individual difference affects the rate of disappearance of intensity	21-28 days disappeared, the patient's individual difference affects the rate of disappearance of intensity	More than 85% of the original strength can be maintained in one week, and more than 55% in two weeks. There is no obvious individual difference.	5/0, 6/0 can maintain tension for more than 1 week, 4/0, 4 / 0T can maintain for more than 12 days, the rest is thickened by the diameter of the wire, and the maintenance time is gradually extended.
Absorption method	Non-absorptive	Hydrolyzed and absorbed by body tissue	Hydrolyzed and absorbed by body tissue	Simple hydrolysis process	Enzymatic digestion by body tissues
Products after degradation	no	Carbon dioxide, water	Carbon dioxide, water	Carbon dioxide, water	Amino acid
Absorption speed	Non-absorptive	Usually absorbed within 70 days, but the individual patient's differences affect the absorption process, or even do not absorb	Usually absorbed within 90 days, but individual patients have different influences on the absorption process, even do not absorb	Complete absorption within 60-90 days, stable and reliable absorption and prediction, no obvious individual differences	Completely absorbed in 8-15 days, and the absorption is stable and reliable without obvious individual differences
Tissue response	obvious	Moderate	Moderate but less reactive than normal bowel	Mild, significantly lower than the gut	no
With or without chemical coating	Cotton fabric no, polymer yes	no	no	Have	no
Thread structure	Braided	Single fiber	Single fiber	Single fiber	Single fiber
Whether absorption is complete	Not absorbed at all	A little does not absorb	A little does not absorb	A little does not absorb	Fully absorbed
Protective fluid	no	need	need	no	no

2. Medical sutures 2. Non-absorbable sutures

Non-absorbable sutures are sutures that cannot be absorbed by tissues, so sutures need to be removed after sutures, which have different degrees of tissue response, and sutures easily leave scars on the epidermis. Made of special silk or synthetic fiber polypropylene, polyester or nylon. The specific time for suture removal varies depending on the suture site, the wound and the patient's condition. When the wound heals well and there are no abnormalities such as infection: the suture is removed on the face and neck 4 to 5 days; the lower abdomen and perineum 6 to 7 days Chest, upper abdomen, back, buttocks for 7-9 days; limbs 10-12 days, the joints can be extended a little longer, and the suture can be removed after 14 days. For special conditions such as malnutrition and large incision tension, it may be appropriate to consider prolonging the stitch removal time. Teenagers can shorten the time for disconnection, and elderly people with diabetes, people with chronic diseases can delay the time for disconnection. After the wound has obvious infections such as redness, swelling, heat, and pain, the suture should be removed in advance. In the following cases, the disconnection should be delayed:

Those with severe anemia, weight loss, and mild cachexia.
Severe water loss or water and electrolyte disorders have not been corrected.
Elderly patients and infants.
When the cough is not controlled, the suture of the chest and abdominal incision should be delayed.

Medical suture physical properties

1. Medical sutures 1. suture diameter

The most basic principle for selecting sutures is to use as thin a suture as possible with a high tensile force and the least response to the tissue. The thickness of various sutures is indicated by numbers and zeros. The larger the number, the thicker the suture; the unit of the diameter of the suture is millimeters, which is usually expressed by several zeros. The thinner the suture, the greater the number of zeros. For example, a nylon with 6 zeros is thinner than a nylon with 4 zeros. But the actual thickness depends on the material of the suture. For example, the same 5 zeros, the gut line is thicker than the polypropylene synthetic thread (ProleneTM). The principle of selecting the thickness is to choose the suture as thin as possible under the conditions that can withstand the tension of the wound. ^[4]

2. Medical sutures 2. Tensile strength

The United States Pharmacopoeia (USP) is defined as the minimum strength that can break a single suture. Therefore, the tensile strength refers to a specific tensile value and a non-linear interval. Effective tensile strength refers to the tensile strength of the suture after it is looped or knotted. The tensile strength of the same kind of suture after knotting is 1/3 of its unknotted. Generally speaking, synthetic material sutures have greater tensile strength than sheep intestinal sutures, and tendon sutures have greater tensile strength than synthetic material sutures.

3. Medical sutures 3. Structure

Structure refers to whether the suture is single-stranded (monofilament) or multi-stranded (braided). Multi-strand sutures are woven, which are easy to handle but increase the chance of infection and tissue reaction. It is easy to cause infection because it has siphon effect to allow bacteria and foreign bodies to infiltrate. The bacteria are hidden inside the braid and can escape the host macrophage. Therefore, monofilament threads (nylon or polypropylene) are more suitable for sutured contaminated wounds. However, monofilament threads are not easy to handle.

4. Medical sutures 4. Coefficient of friction

The coefficient of friction of the suture determines whether the suture easily penetrates the tissue. Sutures with low coefficients of friction (such as polypropylene sutures) slide easily through tissue and are often used for intradermal sutures. The lower the coefficient of friction, the smoother the suture, and the easier the knot becomes loose. Therefore, when using polypropylene sutures, a few extra knots are often required.

5. Medical sutures 5. Knot fastness

The knot strength refers to the minimum tensile force to loosen the knot, which is proportional to the friction coefficient of the suture. The stronger the knot, the less likely the wound will crack. A suture knot with a high coefficient of friction has good firmness, but it has high resistance when it passes through the skin and is not easy to use.

6. Medical sutures 6. elastic

Elasticity refers to the ability of the suture to return to its original length and shape after being stretched by the swelling of the wound. Sutures with good elasticity (such as NovafilTM polybutene ester synthetic thread) are not easy to cut the tissue when the tissue is edema, and it does not loosen after the edema subsides, and the wound is not easy to crack.

Selection principles for medical sutures

1. Absorbable sutures are used to heal faster tissues, especially those where foreign bodies should not be left, such as the gastrointestinal tract, bile ducts, inner urinary tract, myometrium, etc.

2. Non-absorbable sutures are used for slow healing tissues such as cartilage, ligaments, tendons, bronchial tubes, esophagus, and grafts that require long-term fixation.

3. Single-strand fiber sutures are used in vascular surgery and plastic surgery.

4. For some special patients, such as the elderly, diabetic, obese, malnourished, debilitated patients, etc., when selecting sutures, pay attention to the effects of sutures on the speed and process of postoperative wound healing. Suture with comparable toughness and minimal tissue response. ^[4]