Medical surgical suture materials come in many forms, the most common of which are absorbable sutures and non-absorbable sutures. Absorbable sutures have traditionally been used exclusively for closing internal tissues. However, recently the use of absorbable sutures in percutaneous wound closure is becoming increasingly popular. There are many advantages to this procedure, including no need for return visits to the doctor to remove sutures, low risk of infection, and minimal scarring. One of the latest advances in suture closure: barbed sutures, which eliminate knots, distribute wound tension and improving suture efficiency has changed the way doctors work. Recently, according to the quality of suture materials, different categories of suture materials have been developed based on their ability to promote tissue suturing and wound healing. Surgeons should select appropriate suture materials for tissue suturing to improve healing and minimize the possibility of scarring. To avoid ischemia, excessive wound tension and tissue damage, antimicrobial agents are also added to absorbable suture materials to provide additional external protection, making it stronger while maintaining high tensile strength and good operability. This article attempts to introduce the various existing absorbable suture materials and their corresponding applications.

1.      Introduction

Sutures are mainly used to sew tissues together to help and speed up accidents or the recovery process after surgery. In addition, sutures also help to eliminate dead space and evenly distribute reduce the stress on the incision line and maintain sufficient tensile strength throughout the critical process of wound healing. Although staples, tape, and adhesives can be used

to close the wound, but sutures are the most commonly used method of wound closure. Considering the suture material, there are so many different types of sutures available, and it is important to understand the differences between them before making an informed decision. The overall performance of suture materials is influenced by their physical properties, handling characteristics, and biological factors. During the suturing process, a high degree of flexibility and elasticity is required for effective application. It is easy to tie knots, has high knot safety, does not contain irritating or infectious chemicals, and is also a suture. The material should be sterile, free of electrolytes, non-ferromagnetic, no capillaries, no carcinogenicity, no teratogenicity, no allergy, easy to use, quick and painless, aesthetically pleasing and not a source of bacterial infection. It must be resistant to shrinkage, have minimal tissue reaction, sterilization is simple without changing its properties and is cost-effective.

However, it is also important to note that no single suture material can satisfy all of these each form of suture has unique properties that must be examined before use. In the past few years, the properties of suture materials and the promotion of tissue suture and injury, the ability of wound healing has been improved and the types of suture materials have increased.

Suture support varies greatly between tissues, with some tissues requiring only a few days of support, while others may require only a few days of support. Some tissues may require support for weeks or even months. Short-term suture support is needed. This suture method does not require suture removal and does not cause discomfort. This article aims to provide an overview of the currently available absorbable classification of collection sutures, salient features, properties, advantages and applications of suture materials.

2.      Historical Perspective

Suture materials have been used or proposed for thousands of years. Sutures made of plant (cotton, linen, and hemp) and animal (tendon, hair, muscle strips, and nerves, arteries, gut and silk).

The use of surgical sutures can be traced back to ancient Egypt in 3000 BC. The first documented use of sutures was found in a mummy dating back to 1100 BC. In 500 BC, the Indian wise man and physician, Susanna described in detail. Hippocrates, the father of Greek medicine, and later the Roman Aulus Cornelius Celsus, all described sutures. Galen, a Roman physician in the second century AD, proposed the mechanism of suturing.

In the 10th century, Abulcasis invented the catgut suture and the hand. To make catgut sutures, you need to collect catgut, and it is made in the same way as guitars and violins.

Joseph Lister advocated sterilization of all sutures. In the 1860s, "phenol gut" was used as the first sterilized product. Twenty years later, he sterilized chrome gut. Lord Moynihan found that "chromic acid" sheep intestine is very ideal because it is non-irritating and has a twice the tensile strength and could be sterilized. Finally, in 1906, he developed the first iodine-treated sterile catgut was invented.

The next major development occurred in the 20th century. The chemical industry began to manufacturing of the first ever synthetic thread, producing a variety of non-absorbable and absorbable types. In 1931, the first absorbable synthetic suture using polyvinyl alcohol was invented. Polyester was invented in the 1950s and established a niche for gut and later, radiation sterilization technology for polyester fibers was used. Polyglycolic acid was first used in the 1960s, it was discovered and began to be used for its intended purpose in the 1970s. Today, synthetic Polymer threads have become the mainstay of modern sutures. Since ancient times, only a few materials have been used for suturing: Silk and gut. Due to the problem of BSE, gut suture is limited in Japan. However, the use of silk sutures to close wounds is still a common practice.

3.      Characteristics of suture materials

With the development of new sutures/suture materials, we should be familiar with the different properties of each suture/suture material allow for better use of the most appropriate product. Physical properties can be extensively studied based on the following variables:

Tensile Strength: USP (United States Pharmacopeia) defines tensile strength as the tensile strength required to break a suture.

Tissue absorption: The body's ability to dissolve sutures over time is called resorption capacity.

Cross-sectional diameter: It is best to choose a suture diameter that is small enough to fit into the native tissue strength and expected forces on sutures.

Coefficient of friction: describes how smoothly a suture moves through tissue.

Knot strength and knot security: This describes the ability of the suture to be tied with as few knots as possible. Calculate the strength of the knot to determine whether it will break or slip.

Elasticity: refers to the ability of the material to stretch when the wound is swollen, and then recover after the edema is reduced and return to original length.

Plasticity: Elasticity and plasticity are inseparable. Sutures stretch as wound edema occurs. The ability to maintain a permanent deformation after the edema subsides is called plasticity.

Memory: After the suture is taken out of the package and stretched, it returns to its original compactness.

Maneuverability: The maneuverability or flexibility of a suture is affected by its memory, elasticity, and plasticity. The coefficient of friction and flexibility also affect the handling. The ability of the suture to bend is called flexibility.

Tissue reactivity: Inflammation is a common response to foreign substances and may impede wound healing combination and increase the possibility of infection.

Construction: Sutures can be monofilament (one strand) or multiple strands (multifilament).

Capillary absorption: The ability of a suture to spread liquid along its entire length. This is crucial when dealing with bacteria.

Liquid absorption: Although capillary absorption is different from liquid absorption, both may increase the risk of germ transmission and contamination.

Antimicrobial properties: This can be achieved by adding antimicrobial properties to the suture or by adding a coating to the outside to reduce bacterial adhesion to sutures.

Ease of Removal and Color: Sutures can be colored or uncolored. Dyed sutures are more easier to apply and remove because the dye makes it more visible. Undyed sutures may not be as visible. If it is not so obvious, undyed sutures can be used if removal is not necessary.

Another important property is that it is non-carcinogenic.

4.   Suture: The structure and physical properties are determined by the fiber structure, material surface texture and according to their properties, surgical sutures can be classified into various categories (Figure 1 shows a general diagram).

Figure 1: Overview of suture types based on the physical and structural characteristics of the suture material.

Absorbable sutures: These sutures break down and degrade after implantation, either due to enzymatic degradation and subsequent hydrolysis, or simply hydrolysis. Absorbable sutures are usually used for deep tissue. Temporary closure of tissue until critical wound healing period, or in difficult to remove tissue. If used on the surface, it may cause additional inflammation. If absorbable sutures are to be used superficially, it is recommended that they be used with a faster absorption rate. However, newer absorbable sutures may last longer and it needs to be noticed. For absorbable natural materials, enzyme degradation is used. For new synthetic absorbable sutures, absorbable sutures are divided into four types: natural absorbable sutures, synthetic absorbable sutures, antimicrobial synthetic absorbable sutures and barbed sutures (not combined into absorbable sutures).

Natural absorbable sutures: Preparation of purified connective tissue using sheep intestinal mucosa or bovine intestinal serosa. In the past, surgeons preferred to use catgut, but due to its low tensile strength, unpredictable absorption, and poor adhesion to synthetic suture materials, its use is significantly reduced.

Synthetic absorbable sutures: Today, most absorbable sutures are synthetic and made from a variety of absorbable polymers. They take as long as: Short term (about 50 days): Used for episiotomy or rapid healing of tissues (skin and mucous membranes), etc. For example: rapid Polyglactin 910 fast. Medium term (approximately 60 to 90 days): For soft tissue, Sutures - Orthopedics, General Surgery, Ophthalmology, Plastic Surgery, Gynecology, Urology, Maxillofacial Surgery and Neurology. For example: polyglactin 910, polyglycolic acid, poliglecaprone-25. Long term (approximately180 to 390 days): Used in vascular surgery, abdominal wall closure and orthopedic surgery. Example: polydioxanone, polyester p-dioxanone, poly 4-hydroxybutyrate

Antimicrobial synthetic absorbable sutures, the most common postoperative complication is local surgical wound infection (SSI, surgical wound infection). During reconstruction or when using implanted devices, infections caused by attachment and growth on the surface of devices or implants are a serious challenge. Suture materials are coated with antimicrobial agents such as triclosan or chlorhexidine to reduce bacterial, thereby reducing the incidence of SSI. Promote wound healing and prevent wound infection.

Barbed/non-barbed absorbable sutures:   Barbed synthetic absorbable suture. It is called barbed suture/knotless surgical suture. The barbs embedded in the tissue can serve as the suture. This is an alternative to traditional sutures and provides a use in complex reconstructive surgeries and minimally invasive surgery. Barbed sutures can be used to improve soft tissue vascularization. In recent years, barbed sutures have been successfully used in many professional fields. Including plastic surgery, general surgery, gynecology and obstetrics, urology, orthopedics and other special surgery technique, especially in minimally invasive surgery.

Application and characteristics of absorbable suture materials. Based on surgeon preference, anatomical site, and their specific suture characteristics, absorbable sutures can be divided into the following types (Table 1).

5. Appropriate suture material

Surgeons will choose the appropriate suture material according to different situations: i) Due to different body tissue thickness, flexibility, healing rate, and tendency to scarring vary from person to person and change with age.

The patient's age and health condition vary, so the treatment should be based on the patient's age, weight, health condition, and incision. ii) Complications such as dermatitis, heart disease, diabetes, and steroids. The presence of infection and specific characteristics of the wound may affect wound healing. iii)      The number of tissue layers required to close the wound, the tension of the wound, and the force, the depth of tissue to be sutured, the presence of edema, the time to suture removal, inflammatory response and sufficient strength plays a vital role in the selection of suture materials in wound treatment. iv) Doctors should choose a product with a high strength-to-diameter ratio, constant diameter, sterility, flexibility, and good materials with improved tissue acceptability and functional predictability.

6. Advantages and disadvantages of absorbable sutures

01. Advantages of absorbable sutures: The advantages of absorbable sutures are as follows: For suture support or when suture removal is difficult or uncomfortable due to anatomical location, use absorbable sutures are extremely beneficial; they facilitate rapid re-epithelialization; they have the greatest tensile strength; minimal foreign body reaction; use of rapidly absorbable sutures reduces scar development. Monofilament synthetic absorbable sutures and antimicrobial coated sutures minimize infection risk; knotless sutures are faster and less operator-dependent; Faster and more effective in wound repair and postoperative problems; no cross-marks on sutures, the cosmetic effect is better; stitch removal and the discomfort it brings are avoided.

02. Disadvantages of absorbable sutures: Disadvantages of absorbable sutures are as follows: In some cases, the sutures may as a foreign substance is present for a brief period of time and may trigger a local antigen-antibody reaction. Another disadvantage is that it may exacerbate existing infection. Wound dehiscence can be seen as another major disadvantage. When used to connect areas that may swell, stretch or expand, absorbable sutures may cause wound dehiscence. When applied to tissues with poor blood supply (e.g., epithelial tissue). When the suture is exposed and there is severe local inflammation, the absorption process may be delayed. When absorbable sutures are placed on the skin surface, they may remain for a long time and penetrate the epidermis from the wound. This may affect the healing scar. Absorbable sutures should not be placed close to the skin. This reduces the rate of absorption and increases the likelihood of epithelialization of the suture channel. Epithelialization may lead to cyst formation and permanent suture marks.

7. Conclusion

Absorbable sutures are an important medical invention in wound management and have seen an increase in recent years. According to the characteristics of sutures and their ability to promote tissue connection and wound healing, with the innovation of materials science and technology, the types of suture materials are increasing. Many different types of absorbable sutures have been designed over the past few decades, with varying degrees of stretch. Strength retention, absorption rate, antimicrobial coating, and the benefits of the latest forms of knotless sutures. The increasing availability of absorbable sutures has enabled modern surgeons to suture almost any tissue in the body. Appropriate absorbable sutures can be selected for suture/connection, except for tissues that require permanent support. To promote wound healing and scar beauty, surgeons should choose the most appropriate suture. Therefore, understanding the properties of sutures is essential to minimize tissue damage, excessive wound tension and ischemia are critical. Choosing the appropriate suture for a specific procedure is an important factor. This article focuses on the different physical and mechanical performance of absorbable sutures, enabling surgeons to select appropriate absorbable in the different situation.