Suture material in surgery: classification, properties and modern requirements

1. Story
2. Classification of suture materials
3. Properties of suture material
4. Modern requirements for surgical suture material
5. Application of surgical threads
6. Possible complications when using suture material
7. Classification of needles

Medical sutures are surgical threads designed to join tissue cut during surgery or injury. After some time, a scar or epithelium forms at the site of the suture.

Surgical threads are an important element of the operation; the speed of wound healing and the patient’s recovery depend on their quality. In this case, not only the quality of the suture material itself is important, but also the correct choice of one or another type of thread. There are many medical suture materials designed for different surgical situations. The history of surgical threads goes back several thousand years. During this time, a broad classification of these materials has emerged and it continues to expand with the development of science, technology and production.

Story

As early as 2000 BC, a Chinese treatise on medicine described an intestinal suture using threads of plant origin. The Edwin Smith Papyrus, estimated to be 4,000 years old, describes the ancient Egyptians' use of linen surgical sutures. As a rule, they have not been used in modern medicine for a long time.

From ancient times to this day, only 2 types of natural surgical threads are used: catgut and silk. Catgut was first used as a suture material by Galen in 175 BC. e., having received it from the submucosal layer of the cow intestine. The use of silk in surgery was recorded in 1050 BC. e.

The use of synthetic non-absorbable surgical sutures dates back to 1927, after the American chemist Wallace Hume Carothers created nylon fiber. In the 1930s, nylon based on polyamides and lavsan based on polyesters were created in the West. And in 1956 they obtained polypropylene and began to use it in medicine.

The first self-absorbable threads were created in 1971. Now these are catgut, caproag and PDA threads and others.

Science does not stand still; from time to time scientists manage to obtain new synthetic materials with better properties. Over time, they begin to be used in medicine, in the form of suture materials.

Features of care

Polyester added to wool, linen, and cotton threads simplifies the care of products. Reviews of items made from mixed fabrics are mostly positive: comfort, durability, pleasant appearance. Terylene is characterized by some rigidity, so clothes tolerate washing well in an automatic machine and do not become deformed.

Knowing the properties of terylene, what kind of material it is, and how to care for it, it is easy to remember the following recommendations:

• no pre-soaking required;
• Preferably hand wash at 30ºC;
• use liquid detergents;
• bleaching is prohibited;
• select delicate spin mode;
• dry under a canopy in a straightened form;
• iron from the inside out by turning the iron dial to the first position.

Traditional lavsan and terylene fabrics continue to be in demand, but they have already been replaced by modern, improved types of synthetics. The buyer does not need in-depth knowledge of terylene - what kind of fiber it is. If you need something that won't deteriorate after the first wash, choose clothes made from polyester fibers.

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Classification of suture materials

Surgical threads can be classified according to the following properties:

1. by material;
2. by structure;
3. by ability to biodestruction;
4. by thickness;
5. according to the method of connection with the needle.

By material

1. Natural. These are threads made from natural materials.

1.1. Organic. Made from animal tissue. Organic suture materials include:

• catgut, obtained from the serous tissue of cattle; often causes inflammation;
• silk extracted from the cocoon of the silkworm; high probability of inflammation, but less than in the case of catgut;
• horsehair;
• threads from fascia, tendons, arteries of animals;
• human umbilical cord threads;
• cellulose derivatives - rimin, cacelone, occelone.

1.2. Inorganic. Made from inorganic natural materials. Inorganic suture materials include wire:

• platinum;
• steel;
• nichrome.

2. Synthetic. These are threads made from artificial materials obtained in production.

2.1. Polydioxanone derivatives. Polydioxanone is devoid of antigenic or pyrogenic properties and during the absorption process causes only a mild tissue reaction. These are PDO threads. Polydioxanone thread retains its strength for a long time. By 6 weeks, PDO retains up to 40-60% of its original strength. Complete loss of strength occurs at 180-210 days.

2.2. Derivatives of polyglycolic acid. Absorbable, durable sutures for medium-term wound support that hold the knot well. They are not collagen, non-antigenic, non-allergic, and non-toxic.

• A copolymer of derivatives of glycolic and lactic acids, polyglactin-910, from which the following threads are produced: vicryl - a braided thread with a coating consisting of polyglactin-370 and calcium stearate; PGL (PGK) - domestic twisted and PGA - domestic braided suture material.
• Copolymer of glycolide and E-caprolactam - monocryl.
• Copolymer of glycolic acid and trimethylene carbonate - maxon.
• Homopolymers of polyglycolic acid - dexon.

2.3. Polyolefins: polypropylene, prolene, polyethylene, sirgipro and surgilene. Non-absorbable material that does not lose its properties even after many years of being in the body. Reliable, tear-resistant and elastic.

2.4. Polyesters: lavsan, mersilene, etiflex, polyester, surgidac, dagrofil, ethibond, astralene, ti-cron, dacron and terylene ( terylene). Non-absorbable suture material. Flexible and durable, holds a knot well. Has high manipulation properties.

2.5. Polybutesters. A non-absorbable material with excellent knot strength, minimal trauma, resistant to fiber disintegration, and does not cause an inflammatory reaction. Novafil threads are made from it.

2.6. Fluoropolymer materials: fluorest (ftorest), fluorlin, fluorex, fluorlon and gore-tex. Non-absorbable suture material with high strength, biological inertness and good handling properties.

By structure

1. Monofilament is a thread consisting of one fiber.

2. Polyfilament is a thread consisting of several fibers.

2.1. Twisted. The fibers of such threads are twisted along the axis. Nylon, flax and twisted silk belong to this type of suture materials.

2.2. Wicker. The fibers of such threads are woven. These include mersilene, lavsan, nurolone, mersilk and others.

Multifilament threads are stronger than single-filament threads, which means their handling properties are higher; using multi-filament threads requires fewer conditions, which means less tissue trauma. Polyfilaments hold a knot better, but they have one drawback, which is that their surface is heterogeneous and rough. Because of this, they can injure and cut tissue like a saw. In addition, infection can accumulate between the fibers of polyfilaments when the thread passes through infected tissue and is transmitted to healthy tissue. This is called the wick effect. In order to eliminate the “saw effect” and “wick effect,” multifilament surgical threads are coated with a special coating that makes their surface smooth and adds an antimicrobial effect. Such multi-filament threads are called combined.

According to biodegradability

1. Absorbable. Threads that can completely dissolve in human tissue over a certain period of time.

1.1 Natural. Threads obtained from serous tissue of cattle. These include catgut. The biological strength of a regular thread is 7-10 days, and chrome thread is 15-20 days. The period for complete resorption of a regular thread is 50-70 days, and chrome thread - 90-100 days. The rate of resorption of catgut depends on human health, as well as on the health of the animal from which the thread was made. The breakdown of this thread in the body occurs by cellular proteolytic enzymes.

1.2. Synthetic. Synthetic thread made from polyglecaprone, polyglycolic acid and polydiaxonone.

1.2.1. Short resorption period. Threads made from polyglycolic acid derivatives. Biological strength is 7-10 days, and the period of complete resorption is 40-45 days. Well suited for all operations in which 7 days are enough to form a scar; a good option, for example, for intradermal cosmetic sutures.

1.2.2. Medium resorption period. The biological strength of braided threads is 21-28 days, and the period of complete resorption is 60-90 days. For monofilaments, the biological strength is 18-21 days, and the period of complete resorption is 90-120 days. Medium-absorbable surgical sutures are most often used in surgery.

1.2.3. Long resorption period. Made from polyglyconate or polydioxanone. These are monofilament threads made from 1 fiber. The biological strength of braided threads is 40-50 days, and the period of complete resorption is 180-210 days. Used for suturing tendons, cartilage and fascia. Most often used in traumatology, maxillofacial surgery and thoracic surgery.

2. Conditionally absorbable. Such threads include nylon, silk and polyurethanes.

• Silk is a natural suture material with high strength, softness and ductility. But due to its natural origin, it often leads to inflammatory reactions, suppuration and the formation of microbes in the wound. It is absorbed in the body from six months to a year.
• Nylon or polyamides are one of the first synthetic materials. It is not very suitable for surgical operations, as it causes low-grade inflammation as long as the thread is in the human body. Polyamide monofilaments cause less reaction, braided ones cause more, and the highest reaction of the body occurs to twisted threads. More often used for suturing blood vessels, tendons, bronchi and organs of vision. Dissolve in the body within 2 - 5 years.
• Polyurethanes are monofilaments with high handling properties - flexible, ductile and soft. Does not cause inflammation in tissues. Does not cut the wound, is able to stretch during swelling and return to its original state when the swelling subsides. It is used in plastic, vascular, general surgery, gynecology and traumatology. Dissolves in tissues after 5 - 8 years.

3. Non-absorbable. Threads that do not dissolve in the tissues of the body at all.

• Polypropylene is a monofilament that does not cause a reaction in the body. Can be used in infected tissues and does not lead to the formation of keloid scars and ligature fistulas. But they have poor handling properties and require a large number of nodes. They are used in almost all areas of surgery where a non-absorbable thread that does not cause inflammatory processes is required.
• Polyester is a woven thread that causes a weak reaction in the body. They have very high strength. They are used only in cases where strength and good thread tension are needed for a long time after surgery. In other cases, polyester is inferior to polypropylene. Fluoropolymer materials are threads that have all the properties of polypropylene threads, only more flexible, softer and more ductile. Requires fewer nodes.
• Steel, titanium - metal threads. They can be either braided or monofilament. Used in traumatology, orthopedics and general surgery.

By thickness

The diameter of most surgical sutures ranges from 0.1 to 0.9 millimeters. To indicate the thickness of the suture material, the metric size (EP) is used, which is defined as multiplying the actual diameter of the thread in millimeters by 10. For example, for a thread with a diameter of 0.1, the metric size will be equal to 1.

According to the method of connection with the needle

1. Pressing the thread into a surgical needle. Now this is the most common connection method. The needle included with the thread is disposable and cannot be reused. In modern production, a hole is burned in a needle with a laser, a thread is inserted into it and crimped, which gives high strength at the junction and does not deform the needle. In some industries, a needle is drilled and then a thread is inserted into the hole, but this technology reduces the strength of the needle, and during the stitching process it can become deformed; in addition, a burr can form at the drilling site, which will injure the tissue during stitching.
2. Threading a thread into the eye of a surgical needle. Connection option for reusable needles. Such needles are now practically not used. At the junction of the thread with the needle, with this connection method, a nodule is formed, which, when passing through the tissue, injures it, which increases the amount of blood at the stitching site, increases the likelihood of inflammation and increases the healing time.

Questions and answers

How to wash terylene products?

This is a very strong material. It does not shrink in hot water and does not deform when passing through the squeezing rollers of a washing machine. However, in order for finished clothes to retain their attractive appearance, manufacturers recommend washing them in water at temperatures up to +40°C - this is due to the fact that other, less resistant materials are used when sewing (for example, non-woven fabric for duplicating the base or cotton threads for seams) .

Is it possible to iron things made of lavsan?

Lavsan tolerates this procedure well if you do not heat the iron above the temperatures recommended by the manufacturer. Since scorch marks may appear on the front side of the fabric, it is better to iron items from the reverse side.

Now you know what terylene is and what is special about this material. But if you set out to sew something from it, keep in mind that you don’t have to look for lavsan in stores. Almost all polyester fabrics - for example, the same polyester - have similar properties.

Properties of suture material

1. Manipulative properties. A number of parameters that determine how convenient it is to use the thread. These parameters include flexibility and elasticity. Flexible threads are easier to manipulate and cause less tissue damage. The elasticity of threads is the ability to stretch along with tissue swelling. Non-elastic threads do not stretch, but cut through the fabric. The thread should be moderately elastic so that on the one hand it holds the tissue for healing, and on the other hand it does not cut through or injure them during swelling.
2. Memory effect. The ability or inability of a thread to return to its original state after being stretched. A thread without a memory effect can stretch when the wound swells and shrink back to its original state when the swelling subsides, thereby supporting the tissue in any case. The memory foam thread will stretch when swelling occurs and will not shrink back when the swelling subsides, thereby weakening the compression of the wound, which can lead to complications.
3. Strength. The ability of a thread to withstand tensile load. The stronger the thread, the larger the wound can be closed using less thread. The stronger the material from which the thread is made, the smaller the diameter of the thread is needed and the less traumatic the process of stitching fabrics will be.
4. Biocompatibility. This is the ability of the suture material to be compatible with the tissue and not cause rejection, irritation and inflammatory reactions. Biocompatible threads do not cause any reactions in the body.
5. Wick effect. This is the ability of suture material to capture bacteria and microorganisms from the wound, transfer them to healthy tissue, and promote the development of infection. Uncoated polyfilaments have a wicking effect, while monofilaments do not have this effect.
6. Knot strength. The ability of a thread to hold a knot. The stronger the knots, the fewer of them are needed to stitch the wound. The fewer nodes on the wound, the better, since there is less tissue trauma. Multi-filament threads have the best knot strength, while single-filament threads have the worst.
7. Biodegradation. The ability of a surgical thread to be absorbed. According to the degree of biodegradation, threads can be divided into absorbable, conditionally absorbable and non-absorbable.

Composition of lavsan

Terylene is literally made from petroleum. In the process of processing “black gold”, two substances are obtained - ethylene glycol and dimethyl terephthalate, which are later combined at a certain temperature and pressure. As a result, PET polyester fibers are formed, which are subsequently used to produce fabric.

Without going into details, we can say that the composition of lavsan is 100% polyethylene terephthalate (this is the name of a solid transparent substance that, through cunning production manipulations, is transformed into material for sewing clothes and household textiles).

Modern requirements for surgical suture material

1. Sterility. Absence of all types of microorganisms on the surface of the threads. Suture material must be sterilized.
2. Versatility. Applicability of threads of the same type for various types of operations.
3. Biodegradation. The ability to be completely absorbed, in a time longer than necessary for scar formation. At the same time, no destruction products should remain in the body; they should not be included in metabolic processes and should not have a negative effect on the body.
4. Strength. The thread must be strong at all stages of wound healing.
5. Inertia. Absence of allergic, toxic, teratogenic, carcinogenic effects of suture material on tissue.
6. Node reliability. The knot must be strong and able to withstand the load of the fabric. The tensile strength in the knot should not be lower than the strength of the thread itself.
7. Resistance to infection. The thread must be resistant to infection and must not become a carrier of infection into healthy tissue.
8. Good handling properties. Comfortable in the hand, soft, ductile, flexible, elastic and no thread memory.
9. Lack of electronic activity. The thread should not accumulate a static charge.
10. No allergenic properties. Surgical suture material should not cause allergic reactions in the body.
11. Atraumatic. No sawing or tearing effect of the thread.
12. Small volume. With high strength and elasticity, the thread should not have a large diameter.
13. No absorption effect. Modern suture material should not contribute to the accumulation and spread of infection, fermentation and swelling of the wound.
14. No gluing effect. The thread should not stick to surrounding tissues.
15. Low cost. Surgical threads should be affordable.

In Russia, GOST 31620-2012 Surgical suture materials is in force, which describes the requirements for modern surgical suture material.

Advantages and disadvantages

It is generally accepted that there is nothing good about synthetics and that they are always inferior to natural fabrics. In fact, any material has both positive and negative qualities. Lavsan is no exception, so we have made a comparison table that describes all the characteristics of this canvas.

Application of surgical threads

Most common suture applications by medical field:

1. General surgery:
   polypropylene;
2. polyurethane;
3. steel;
4. absorbable, any period of resorption.
5. Traumatology:
   polyurethane;
6. polyester;
7. polypropylene;
8. steel;
9. absorbable, with a long period of resorption.
10. Vascular surgery:
    polyamide;
11. polyurethane;
12. polypropylene.
13. Plastic surgery:
    polyurethane;
14. absorbable, with a short period of resorption.
15. Thoracic surgery:
    polypropylene;
16. absorbable, with a long period of resorption.
17. Gynecology:
    polyurethane.
18. Cardiac surgery:
    polyester;
19. steel.
20. Maxillofacial Surgery:
    absorbable, with a long period of resorption.
21. Orthopedics:
    polyester;
22. polypropylene;
23. steel.
24. Ophthalmology:
    polyamide;
25. polypropylene.
26. Oncology:
    polypropylene;
27. absorbable, with a long period of resorption.

Possible complications when using suture material

Complications when using suture material can occur when:

• low quality surgical threads;
• incorrect choice of type of suture material;
• violations during surgery.

Possible complications:

• Wound suppuration;
• Dehiscence of wound edges due to suture failure;
• Discrepancies between stitched tissues of internal organs;
• Internal bleeding;
• Accumulation of serous fluid;
• Formation of granulomas and abscesses;
• Formation of fistulas;
• The appearance of a hernia;
• Formation of arteriovenous fistulas;
• The appearance of stenoses and strictures;
• Formation of cholelithiasis and urolithiasis.

In order to eliminate possible complications, the surgeon should use only high-quality suture material and only the type that is suitable for the specific surgical case.