Which closure material is often used internally during a surgical procedure?

Wounds can heal by secondary intention, or they can be primarily closed by a variety of methods. Although the skill and technique of the surgeon are important, so is the choice of wound closure materials. The purpose of these materials is to maintain wound closure until a wound is strong enough to withstand daily tensile forces and to enhance wound healing when the wound is most vulnerable.

Inhaltsverzeichnis Show

Suture Characteristics
Size and Tensile Strength
Multi- and Monofilament Sutures
Suture Degradation: Absorbable and Nonabsorbable Options
Specific Suture Materials: Natural Absorbable Sutures
Specific Suture Materials: Synthetic Absorbable Sutures
Specific Suture Materials: Natural Nonabsorbable Sutures
Specific Suture Materials: Synthetic Nonabsorbable Sutures
Barbed Sutures
Topical Skin Adhesives
CONCLUSIONS
Disclosures
Which suture gauge would be most appropriate for ophthalmic surgery?
Which suture material would be used in the presence of infection?
Which suture property would be helpful in a surgery that has a high risk of infection?
Which of the following sutures does not require removal from the body?

In order to fully appreciate the essentials of a wound closure, it is first important to understand the process of wound healing. Healing occurs in 4 stages—hemostasis, inflammation, proliferation, and remodeling.

The stage of hemostasis begins immediately after injury. While some authors consider this process part of the inflammatory stage, it should be recognized that in the process of hemostasis, the formation of fibrin and degranulation of platelets sets the stage for the subsequent stages. The inflammatory stage begins shortly after injury. In this stage, the immune system mobilizes to remove damaged tissue and bacteria from the wound. The proliferative stage is the tissue-formation stage in which reepithelialization, angiogenesis, and fibroblast proliferation and migration predominate. During the final stage, the extracellular matrix, which is composed of fibronectin, hyaluronic acid, proteoglycans, and type III collagen, is deposited and constantly remodeled with the final accumulation of mature type I collagen. This stage may occur for as long as 6-12 months after wounding.

Wound strength gradually increases throughout the healing process, reaching about 20% of the preinjury strength at 3 weeks. Postinjury skin strength ultimately only reaches 70-80% of that of normal skin. The components of the phases wound healing are depicted in the image below.

Wound healing phases. Image courtesy of Mikael Häggström, Medical gallery of Mikael Häggström 2014, Wikimedia Commons.

Surgeons must select the optimal suture materials for tissue approximation to maximize wound healing and scar aesthetics. Thus, knowledge regarding their characteristics is crucial to minimize ischaemia, excess wound tension, and tissue injury. This article describes the selection of various suture materials available today and their intended design. Modern suture material should have predictable tensile strength, good handling, secure knot-tying properties, and could be enhanced with an antibacterial agent to resist infection. Tensile strength is limited by suture size. The smallest suture size that will accomplish the purpose should be chosen to minimize tissue trauma and foreign material within tissues. Monofilament suture has lower resistance when passed through tissues, whereas multifilament sutures possesses higher tensile strength and flexibility but greater tissue friction and pose risks of suture sinus and infection. Natural absorbable sutures derived from mammalian collagen undergo enzymatic degradation whereas synthetic polymers undergo hydrolysis. Collagen or polymer structures in the suture can be modified to control absorption time. In contrast, nonabsorbable sutures typically cause an inflammatory reaction that eventually encapsulates by fibrous tissue formation. Excess reaction leads to chronic inflammation, suboptimal scarring, or suture extrusion. More recently, barbed sutures have transformed the way surgeons approximate wounds by eliminating knots, distributing wound tension, and increasing efficiency of closure. Similarly, modern skin adhesives function both as wound closure devices as well as an occlusive dressing. They eliminate the need for skin sutures, thus improving scar aesthetics while sealing the wound from the external environment.

The word suture is derived from the Latin sutura, “a sewn seam.” Materials including linen, cotton, horsehair, animal tendons and intestines, and wire from precious metals have been used to approximate wounds and act as ligatures. Many adaptations over time have led to the highly sophisticated products we use in our practice today.

Surgeons approximate tissue daily, but often their choice of suture and needle are based on what they learned in training or through negative events during their careers. The surgeon must be well informed regarding the characteristics of their suture choice and select a suitable material that will minimize dead space and risk of microbial invasion while maximizing precise wound approximation and, ultimately, optimizing scar aesthetics. What suture or suture combinations to utilize in any particular surgical case varies greatly among surgeons. Thus, knowledge regarding the multiple available options gives direction and enables surgeons to develop their own predilections.

The purpose of this article is to familiarize the reader with the general characteristics of sutures, along with the accompanying article on the characteristics of needles, so that operative choices are better understood in the greater scheme of the science of tissue coaptation.

Suture Characteristics

The favorable characteristics of a suture are well documented and include possessing the greatest predictable tensile strength consistent with size limitations, good handling properties, and secure knot tying.1 With time, a surgeon develops suture preferences, specific to their practice, based around their knowledge of tissue healing and the physical and biological characteristics of suture materials and factors such as infection, biofilm formation, and multi-resistant pathogens.2 Modern suture materials are impregnated with a variety of agents that improve their handling, antibacterial properties, and visibility.3,4

Size and Tensile Strength

Suture sizes are commonly denoted using the USP (United States Pharmacopeia) system. This numbering system can be a little confusing, but it centers around the “0” suture. Suture sizes increase from USP size 0 (“zero”) to size 1, commonly called “number 1,” to USP size 2 (“number 2”), and upwards. Alternatively, suture sizes decrease in size, again from 0, to USP size 2-0, commonly called “two 0,” 3-0 (“three 0”), and downwards. Table 1 provides size comparison based on USP denotation, metric gauge, and diameter. An example of an extremely fine suture for ophthalmic and microsurgery such as USP size 9-0 has a metric gauge size of 0.3 and diameter of between 0.030 to 0.039 mm.

Table 1.

Varying Sizes of Synthetic Sutures According to Their US Pharmacopeia Denotation, Metric Gauge, and Diameter (in millimeters)

USP size . Reference . Metric gauge . Diameter (mm) . 3 Three (3) 6 0.600-0.699 2 Two (2) 5 0.500-0.599 1 One (1) 4 0.400-0.499 0 Zero (0) 3.5 0.350-0.399 2-0 Two zero (00) 3 0.300-0.339 3-0 Three zero (000) 2 0.200-0.249 4-0 Four zero (0000) 1.5 0.150-0.199 5-0 Five zero (00000) 1 0.100-0.149 6-0 Six zero (000000) 0.7 0.070-0.099 7-0 Seven zero (0000000) 0.5 0.050-0.069 8-0 Eight zero (00000000) 0.4 0.040-0.049 9-0 Nine zero (000000000) 0.3 0.030-0.039

Table 1.

Varying Sizes of Synthetic Sutures According to Their US Pharmacopeia Denotation, Metric Gauge, and Diameter (in millimeters)

The purpose of sutures in general is to approximate tissues, without excess tension, while minimizing ischaemia and tissue injury. As wound healing progresses, the wound strength increases over weeks or months until it approximates the original tensile strength of the tissue. Whether wound closure is single or multilayered, the smallest size or diameter of suture that will accomplish the purpose at hand should be chosen, thus minimizing both tissue trauma with each passage of the needle and the amount of foreign material left behind. Smaller-diameter sutures are, however, associated with less tensile strength, and a balance must be struck between size of suture and maintainance of tissue reapproximation.1

Multi- and Monofilament Sutures

Whether a suture has a single or multiple strand composition is an important consideration, especially when weighing its potential for harboring bacteria against the need for greater tensile strength. Monofilament sutures pose lower resistance on tissue passage, are less likely to accommodate organisms, and tend to snug down more readily. On the other hand, they must be handled carefully, because when crushed by certain instruments, they can weaken or break. They are favored in vascular and microvascular surgery where ease of tying down sutures is crucial.

When several strands are braided together forming the multifilament suture, greater tensile strength, flexibility, and pliability is offered. In recent years, coating the suture has assisted its passage through tissue and decreased potential for infection, making multifilament suture the choice for many intestinal surgeries. Multifilament sutures, when used on the subcutaneous or intradermal level, tend to be extruded in the form of a suture sinus or small localized abscess, compared with a monofilament, which behaves in a cleaner, less reactive manner.

Suture Degradation: Absorbable and Nonabsorbable Options

The manner by which a suture degrades influences the material choice for internal use in deeper layers and for skin approximation. Absorbable sutures are typically made from either mammalian collagen, which is ultimately digested by body enzymes, or synthetic polymers that undergo hydrolysis. Hydrolysis is a process where water penetrates the suture strands, causing breakdown of the filament’s polymer structure. Maintaining the balance between rapid absorption and the prolongation of tensile strength has been aided by treatments and chemical structuring, which lengthen absorption time.

Typically, when a wound is closed with absorbable suture, the decrease in tensile strength over the first weeks is in a gradual, linear fashion. During this period, a leukocyte cellular response is mounted to remove cell debris and physical suture material, and this process overlaps with the second stage where the majority of suture mass is lost. Either of these phases can be affected by infection and protein deficiency, where tensile strength is lost too quickly, and wound dehiscence is manifested clinically. Hydrolysis produces a lesser degree of tissue reaction compared with the enzymatic degradation process.

In contrast, the in vivo tissue response around nondegradable material involves fibroblasts that encapsulate the suture by fibrous capsule formation. Adjacent macrophages and foreign body giant cells respond in a process known as frustrated phagocytosis, where they attempt to enzymatically degrade the nondegradable suture.

For example, nonabsorbable Nylon sutures are commonly used to approximate skin edges on the face where aesthetic outcome is crucial. These are removed early to avoid tissue inflammation and unwanted tissue response around the suture material, which would leave undesirable track marks. In contrast, nonabsorbable Prolene sutures can be used for optimal mesh fixation in hernia repair. They are left permanently in situ, where they remain encapsulated by fibrous tissue together with the mesh. When enhanced mechanical strength is required such as in the closure of sternotomy, steel wires are used to achieve bony union.

Specific Suture Materials: Natural Absorbable Sutures

Absorbable sutures may be classified as natural (surgical gut) or synthetic (Polyglactin in its many forms [eg, Coated Vicryl Polyglactin 910, Monocryl Poliglecaprone 25, and PDS II Polydioxanone]).

The naturally occurring types of surgical gut are formed from processed strands of highly purified collagen, which dictates not only the tensile strength but also its degradability. A higher percentage of pure collagen along the strand equates to less foreign material in the wound. An example of the composition of one such gut suture is 97% to 98% pure strands of collagen (serosa of beef intestine, or submucosa of sheep intestine) spun into monofilaments of varying sizes but uniform diameter to within an accuracy of 0.0002 inch. This eliminates variations known as high and low spots, which contribute to frays and breakages in the suture knot that is malpositioned or unsecurely tied down.

Plain surgical gut is a rapidly absorbed suture, generally used for closing the epidermis, ligating superficial blood vessels, and suturing subcutaneous tissue. The tensile strength is maintained for 7 to 10 days and absorption is complete by 70 days. When heat treated, the filaments are absorbed at a more rapid pace and they lose tensile strength compared with their nontreated counterparts. Clinically, it can be placed in the mucosa of the lip and eye and as an external suture for rhinoplasty closure where minimal tensile strength is required.

The corollary is chromic gut, which resists the body’s enzymatic digestion. The collagen filaments are bathed in buffered chrome tanning solution salt before formation into its strands. This process turns the suture yellowish tan to brown. Tensile strength remains for 10 to 14 days, with residual measurable strength present for 3 weeks and absorption time prolonged to over 90 days. The main advantage over plain gut is less tissue reaction.

Specific Suture Materials: Synthetic Absorbable Sutures

One of the most frequently used sutures amongst plastic surgeons is an absorbable suture that holds its tensile strength for a predictable period of time and shows lower tissue reaction than surgical gut. The original introduction to the market of one such suture in 1974 was Vicryl, a braided, naturally absorbing pliable suture, which was later modified in 1979 to improve smoother tissue passage and handling and ensure more secure knot tying (Coated Vicryl). The raw material of this braided suture is a copolymer of lactide and glycolide coated with polyglactin 370 and calcium sterate. It is absorbed by hydrolysis, with 75% still present at 2 weeks, 25% at 1 month, and is completely absorbed by 56 to 70 days and thus useful for soft tissue approximation. In 2003, a broad-spectrum antibacterial agent, triclosan, was added.3,4 Subsequently, an undyed braided suture of similar composition to the original but treated with gamma rays to have a lower molecular weight was designed (Vicryl Rapide) for faster absorption; 50% of tensile strength is lost at 5 days with complete absorption by 6 weeks. It is ideally used for short-term wound support of superficial soft tissue mucosa and skin.

Since its introduction in 1982, PDS II (Polydioxanone) has gained popularity among plastic surgeons. It features a polyester polymer monofilament construct, with 25% of the tensile strength still remaining at 6 weeks and maximum support for the first 2 weeks (70%). The actual absorption is insignificant until 3 months and is essentially complete by 6 months. Because of its minimal tissue reaction, it is also favored in pediatric, cardiovascular, and ophthalmic surgeries.

A synthetic suture specifically for skin closure, Monocryl (Poliglecaprone 25), was introduced in 1993 and is formed of a copolymer of glycolide and epsilon-caprolactone. This monofilament retains 60% to 70% of its tensile strength at 1 week, with complete loss at 3 weeks and complete absorption between 91 and 119 days. Dyed and antibacterial versions have a similar profile.3 This has been the suture of choice for many subcuticular skin closures, including abdominoplasty, flap inset, and breast wound closure.

Specific Suture Materials: Natural Nonabsorbable Sutures

Nonabsorbable sutures are useful for their superior handling characteristics. Raw silk is produced through a process whereby a continuous filament is spun by the silkworm. The silk filaments were processed to become a tightly braided, dyed suture coated with waxes or silicone. Although silk suture is classified as a nonabsorbable suture in the USP, in the materials literature it is considered a degradable material by material scientists. Silk biodegradation is mediated by foreign body tissue response. Slow but progressive enzymatic degradation of the fibers will result in gradual loss of tensile strength.

Surgical stainless steel is used in its 316L low-carbon alloy formula and may be braided into multifilaments. It is most typically encountered by the plastic surgeon reconstructing a sternal wound or in hand fracture fixation. It affords indefinite tensile strength and flexibility and lacks toxic elements, but sensitivity to chromium and nickel may occur in susceptible patients. Wires can be associated with difficult handling, fragmentation, or kinking, which can result in fatigue. There is a risk of tearing tissue and puncturing skin, thus posing risk of virus transmission and the possibility of unfavorable electrolytic reactions.

Specific Suture Materials: Synthetic Nonabsorbable Sutures

Nylons were introduced to the market by the DuPont Company in the late 1930s with Nylon 66, the first true synthetic fiber. Sutures are produced from the long-chain aliphatic polymers Nylon 6 and Nylon 6.6. used for sizes 7-0 and smaller. They lend themselves to a broad range of applications in surgery including skin approximation, vessel ligation, and microsurgery. With the introduction of fine needles and sutures (8-0 to 11-0), the scope for microscopic surgery has greatly expanded in all specialties. For plastic surgeons, it is frequently utilized for anastomosis, neurorhaphy, and oculoplastic surgeries. For aesthetic plastic surgery, a premoistened or “pliabilized” monofilament suture in sizes 3-0 to 6-0 was devised to enhance tissue handling and knot tying to make it more similar to a braided suture.

Nylon monofilament suture (eg, Ethilon) possesses the characteristics of high tensile strength and extremely low reactivity. Both monofilament and its multifilament counterpart (eg, Nurolon) degrade approximately 15% to 20% per year by the process of hydrolysis and are eventually encapsulated if left in place (in vivo study).

In the 1920s, Mersons Manufacturing Company produced the first synthetic braided suture preattached to the butt of the needle, which was shown to remain indefinitely in the body. Mersilene (polyethylene terephthalate) is uncoated and thus has a higher coefficient of friction with passage through tissue, but provides consistent suture tension, and minimal breakage.

Many orthopedic surgeons prefer to use coated polyethylene terephthalate suture (Ethibond Excel), a nonabsorbable braided suture for ligament or tendon repair. It is coated with polybutylate, thus enabling easy passage of the fibers through tissue and smooth knot tying. Being inert, it elicits minimal reaction and its tensile strength is not known to significantly change with time. In the realm of body contouring surgery, when employed to either plicate the abdominal wall or close abdominoplasty incisions, Ethibond can cause sinuses/granulation tissue due to permanent presence of a foreign body in the wound. This can lead to problems arising years after surgery.

Prolene, a widely utilized nonabsorbable synthetic monofilament, is an isostatic crystalline stereoisomer of polypropylene. It tends not to lose tensile strength through degradation and can be used on skin to diminish reactivity or, in a contaminated field, to minimize delayed sinus formation and extrusion. Prolene is commonly utilized as a pull-through suture in facial lacerations and trauma, where aesthetics are paramount and track marks must be avoided.

A less familiar monofilament suture, which is relatively resistant to infection and contamination, is Pronova Poly (hexafluoropropylene-VDF). It is a polymer blend of poly (vinylidene fluoride) and poly (vinylidene fluoride-co-hexafluoropropylene) and is employed in ligation and wound closure, where it resists adherence to adjacent tissues in cardiovascular, ophthalmic, and neurosurgical procedures.

Barbed Sutures

Barbed sutures, first designed by John Alcamo in 1956, were granted a US patent in 1964. The first FDA-approved barbed suture was not available until 2002. This was a unidirectional 2/0 polypropylene suture on a straight needle for midface lift (Contour Thread, Surgical Specialties). Subsequently, barbed absorbable polydioxanone suture was produced for wound closure (Quill Medical).5 The V-Loc unidirectional barbed suture with a fixed loop was introduced in 2009 (Covidien Healthcare) and Stratafix was introduced in 2012. These barbs serve to grip the sutured tissue in a continuous manner and retain tensile strength. The main benefits of barbed sutures include elimination of surgical knots, knot-related complications, and increased efficiency of wound closure.6 The size and spacing of the barbs, which are integrally formed into the core, are designed to provide maximum holding in soft tissue such as fascia and provide tactile feedback to regulate tension. They have become particularly popular for abdominal wall repair following free flap harvest.7 In some barbed sutures, the barbs are created by cuts through the suture thread rather than adding the barb to the suture core, which reduces the original tensile strength of the suture by reducing its functional diameter. Therefore, a larger suture size should be considered routinely.

The clinical advantages of barbed sutures include reduced suturing time and reduced overall operating time.8 These sutures demonstrated a lower rate of wound healing complications in body contouring operations.9,10 Barbed sutures have proven successful in both conventional and robotic urological procedures11 and laparoscopic gynecological procedures.12 Bidirectional barbed sutures performed better than unidirectional barbed sutures, and postoperative complications appear to be higher in cosmetic surgery. In a large clinical series, the 2-layered technique to repair deep dermal and superficial skin layers separately with barbed sutures was associated with significantly higher rates of wound separation. The same study found that the Quill barbed suture was associated with more incisional site erythema compared with the V-Loc barbed suture.13 Therefore, further evaluation is required before their liberal use in reconstructive and aesthetic surgery.

Topical Skin Adhesives

Skin adhesives are popular for closure of low-tension wounds and pediatric traumatic lacerations and serve as a suitable wound dressing in many elective breast and abdominal wall procedures. Butylcyanoacrylate (eg, LiquiBand, Histoacryl), which has proved favorable in well-designed clinical trials,14 is rapid-acting, cost effective, and easy to apply.

Octyl cyanoacrylate (eg, Dermabond) forms a transparent and flexible bond, enabling placement over nonuniform wounds by creating a protective seal and providing the benefits of an occlusive dressing. Its flexibility also overcomes topical shear forces exerted on the adhesive, thereby reducing early wound sloughing and possible dehiscence. Compared with Butylcyanoacrylate, it had twice the breaking strength and was more favorable for longer incisions. One of the main benefits, from an aesthetic perspective, is the fact that there are no evident track marks, particularly where facial aesthetics and pediatrics are concerned. From a patient’s perspective, being able to take a shower in the immediate postoperative period without concern for compromising the incision is of great benefit.1

CONCLUSIONS

Many adaptations and technological advancements in material science have resulted in the production of sutures that have impressive mechanical and physical properties. Not only do they perform their primary function of wound closure, but they afford other benefits such as antimicrobial properties and, more recently, elimination of the surgical knot with barbed suture and replacement of skin sutures with adhesives.

It is imperative that a surgeon develops their own personal choice of suture so familiarity translates to consistent reproducible results. Future generations of sutures will no doubt be innovative and exciting, but the attentive surgeon must always remain mindful of the controllable factors, namely perfection of technique, gentle handling, and appropriate suture selection.

Disclosures

Dr. Aly was a consultant for Ethicon for approximately 15 years and has not consulted with them for several years. He was part of a group of key opinion leaders who offered insights about massive weight loss body contouring. He also contributed to product development. Dr. Byrne declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.

Funding

This supplement is sponsored by Ethicon US, LLC (Somerville, NJ, USA).

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Published by Oxford University Press on behalf of The American Society for Aesthetic Plastic Surgery 2019.

Which suture gauge would be most appropriate for ophthalmic surgery?

An example of an extremely fine suture for ophthalmic and microsurgery such as USP size 9-0 has a metric gauge size of 0.3 and diameter of between 0.030 to 0.039 mm.

Which suture material would be used in the presence of infection?

Polypropylene is a nonabsorbable, monafilament suture that retains its tensile strength in vivo long term. It is as inert as steel and is unaffected by tissue fluids. It also can be used in the presence of infection.

Which suture property would be helpful in a surgery that has a high risk of infection?

As a monofilament suture, polydioxanone causes minimal tissue reaction. It is useful in contaminated wounds or wounds in locations at greater risk for infection. Polydioxanone is also useful as a buried suture in wounds that require prolonged dermal support.