Introduction
Wound closure techniques have evolved from the earliest development of suturing materials to comprise resources that include synthetic sutures, absorbables, staples, tapes, and adhesive compounds. The engineering of sutures in synthetic material along with standardization of traditional materials (eg, catgut, silk) has made for superior aesthetic results. Similarly, the creation of natural glues, surgical staples, and tapes to substitute for sutures has supplemented the armamentarium of wound closure techniques. Aesthetic closure is based on knowledge of healing mechanisms and skin anatomy, as well as an appreciation of suture material and closure technique. Choosing the proper materials and wound closure technique ensures optimal healing.
For excellent patient education resources, visit eMedicine's Procedures Center. Also, see eMedicine's patient education article Suture Care.
Wound Healing
Three phases of wound healing have been identified and studied on the cellular and molecular level. These 3 distinct phases, ie, inflammation, tissue formation, and tissue remodeling, depend on an elaborate cascade of growth factors and cellular components interacting in a directed manner to achieve wound closure.
The initial injury leads to the recruitment of inflammatory cells into the wound, once a clot forms in response to disrupted blood vessels. This scenario entails a complex interaction between local tissue mediators and cells that migrate into the wound. The inflammatory phase occurs in the first few days as inflammatory cells migrate into the wound. Migration of epithelial cells has been shown to occur within the first 12-24 hours, but further new tissue formation occurs over the next 10-14 days.
Epithelialization and neovascularization result from the increase in cellular activity. Stromal elements in the form of extracellular matrix materials are secreted and organized. This new tissue, called granulation tissue, depends on specific growth factors for further organization to occur in the completion of the healing process. This physiologic process occurs over several weeks to months in a healthy individual.
Finally, tissue remodeling, in which wound contraction and tensile strength is achieved, occurs in the next 6-12 months. Systemic illness and local factors can affect wound healing. Traditionally, at least 2 types of wound healing have been described, ie, primary intention and secondary intention.
In the primary intention method, surgical wound closure facilitates the biological event of healing by joining the wound edges. Surgical wound closure directly apposes the tissue layers, which serves to minimize new tissue formation within the wound. However, remodeling of the wound does occur, and tensile strength is achieved between the newly apposed edges. Closure can serve both functional and aesthetic purposes. These purposes include elimination of dead space by approximating the subcutaneous tissues, minimization of scar formation by careful epidermal alignment, and avoidance of a depressed scar by precise eversion of skin edges. If dead space is limited with opposed wound edges, then new tissue has limited room for growth. Correspondingly, atraumatic handling of tissues combined with avoidance of tight closures and undue tension contribute to a better result.
The secondary intention method (spontaneous healing) is ancient and well established. It can be used in lieu of complicated reconstruction for certain surgical defects. This method also depends on the 3 stages of wound healing to achieve the ultimate result.
Materials for Wound Closure
History
The history of sutures begins more than 2,000 years ago with the first records of eyed needles. The Indian plastic surgeon, Susruta (AD c380-c450), described suture material made from flax, hemp, and hair. At that time, the jaws of the black ant were used as surgical clips in bowel surgery. In 30 AD, the Roman Celsus again described the use of sutures and clips, and Galen further described the use of silk and catgut in 150 AD. Before the end of the first millennium, Avicenna described monofilament with his use of pig bristles in infected wounds. Surgical and suture technique evolved in the late 1800s with the development of sterilization procedures. Finally, modern methods created uniformly sized sutures.1
Catgut and silk are natural materials that were the mainstay of suturing products, and they remain in use today. The first synthetics were developed in the 1950s, and further advancements have led to the creation of various forms. The different types of sutures offer different qualities in terms of handling, knot security, and strength for different purposes. No single suture offers all of the ideal characteristics that one would wish for. Often the trade-off is in tissue handling versus longevity versus healing properties.
Sutures
General classification of sutures includes natural and synthetic, absorbable and nonabsorbable, and monofilament and multifilament. Natural materials are more traditional and are still used in suturing today. Synthetic materials cause less reaction, and the resultant inflammatory reaction around the suture material is minimized.
Absorbable sutures are applicable to a wound that heals quickly and needs minimal temporary support. Their purpose is to alleviate tension on wound edges. The newer synthetic absorbable sutures retain their strength until the absorption process starts. Nonabsorbable sutures offer longer mechanical support.
Monofilaments have less drag through the tissues but are susceptible to instrumentation damage. Infection is avoided with the monofilament, unlike the braided multifilament, which can potentially sustain bacterial inocula. Natural materials include gut, silk, and even cotton. Gut is absorbable, but cotton and silk are not. Gut is considered a monofilament, whereas silk and cotton are braided multifilaments.
Various synthetic materials are available for suturing. The absorbable sutures include the monofilamentous Monocryl (poliglecaprone), Maxon (polyglycolide-trimethylene carbonate), and PDS (polydioxanone). Braided absorbable sutures include Vicryl (polyglactin) and Dexon (polyglycolic acid). Nonabsorbable sutures comprise nylon, Prolene (polypropylene), Novafil (polybutester), PTFE (polytetrafluoroethylene), steel, and polyester. Nylon and steel sutures can be monofilaments or multifilaments. Prolene, Novafil, and PTFE are monofilaments. Polyester suture is braided.
Absorbable suture materials lose their tensile strength before complete absorption. Gut can last 4-5 days in terms of tensile strength. In the chromic form (ie, treated in chromic acid salts), gut can last up to 3 weeks. Vicryl and Dexon maintain tensile strength for 7-14 days, although complete absorption takes several months. Maxon and PDS are considered long-term absorbable sutures, lasting several weeks and likewise requiring several months for complete absorption.
Nonabsorbable sutures have varying tensile strengths and may be subject to some degree of degradation. Silk has the lowest strength and nylon has the highest, although Prolene is comparable. Both nylon and Prolene require extra throws to secure knots in place. Polyester has a high degree of tensile strength, and Novafil is appreciated for its elastic properties.
Adhesives
Use of surgical adhesives can simplify skin closure in that certain problems inherent to suture use can be avoided. Problems (eg, reactivity, premature reabsorption) can occur with sutures and lead to an undesirable result, both cosmetically and functionally. Several adhesives have been developed to alleviate this problem and to facilitate wound closure. One substance, cyanoacrylate, has been used for 25 years and easily forms a strong flexible bond. In some forms, it can induce a substantial inflammatory reaction if implanted subcutaneously. If used superficially on the epidermal surface, little problem with inflammation occurs.
Octyl-2-cyanoacrylate (Dermabond, Ethicon, Somerville, NJ) is the only cyanoacrylate tissue adhesive approved by the U.S. Food and Drug Administration (FDA) for superficial skin closure. Octyl-2-cyanoacrylate should only be used for superficial skin closure and should not be implanted subcutaneously. Subcutaneous sutures are used to take the tension off the skin edges prior to applying the octyl-2-cyanoacrylate. Subcutaneous suture placement aids in everting the skin edges and minimizing the chances of deposition of cyanoacrylate into the subcutaneous tissues.
In addition to its surgical adhesive indication, the FDA granted approval in January 2001 for Dermabond to be used as a barrier against common bacterial microbes including certain staphylococci, pseudomonads, and Escherichia coli.
Fibrin-based tissue adhesives can be created from autologous sources or pooled blood. They are typically used for hemostasis and can seal tissues. Although they do not have adequate tensile strength to close skin, fibrin tissue adhesives can be used to fixate skin grafts or seal cerebrospinal fluid leaks. Commercial preparations such as Tisseel (Baxter) and Hemaseel (Haemacure) are FDA-approved fibrin tissue adhesives made from pooled blood sources. These fibrin tissue adhesives are relatively strong and can be used to fixate tissues. Autologous forms of fibrin tissue adhesives can be made from patient's plasma. The concentration of fibrinogen in the autologous preparations is less than the pooled forms; therefore, these forms have a lower tensile strength.
Other materials
Staples provide a fast method for wound closure and have been associated with decreased wound infection rates. Staples are composed of stainless steel, which has been shown to be less reactive than traditional suturing material. The act of stapling requires minimal skin penetration, and, thus, fewer microorganisms are carried into the lower skin layers. Staples are more expensive than traditional sutures and also require great care in placement, especially in ensuring the eversion of wound edges. However, with proper placement, resultant scar formation is cosmetically equivalent to that of other techniques.
Closure using adhesive tapes or strips was first described in France in the 1500s, when Pare devised strips of sticking plaster that were sewn together for facial wounds. This method allowed the wound edges to be joined and splinted. The porous paper tapes (eg, Steri-Strips) in use today are reminiscent of these earlier splints and are used to ensure proper wound apposition and to provide additional suture reinforcement. These tapes can be used either with sutures or alone. Often, skin adhesives (eg, Mastisol, tincture of Benzoin) aid in tape adherence.
Newer products such as the ClozeX (Wellesley, Mass) adhesive strip allows for rapid and effective wound closure that results in adequate cosmesis. Additionally, wound closure with adhesive strips can be significantly cheaper than suturing or using a tissue adhesive. However, adhesive strips are not appropriate for many types of lacerations.
Surgical Technique
Closure by secondary intention
Closure by secondary intention is an adequate alternative to other wound closure techniques, especially on concave areas of the head and neck. The results achieved are aesthetic and functional and can spare the patient more complex procedures such as flap or skin graft reconstruction. Concave surfaces, such as those presented by the auricle, occiput, medial canthus, nasal alar crease, nasolabial fold, and temple, heal well by secondary intention with minimal scarring. This approach is useful, especially in defects (either superficial or deep) resulting from dermatological surgery. The final scar is less noticeable in older patients with skin laxity and in lighter-skinned patients. This method is appropriate in conjunction with other reconstructive techniques.
Basics of facial wound closure
Good approximation of wound edges is paramount to proper wound closure technique. This may entail the placement of deep sutures subcutaneously or in the deepest layer of disrupted tissue; however, in some situations, a single-layer closure is adequate. When placing deep sutures, absorbables (eg, gut, Dexon, Vicryl, Monocryl) are typically used. The knot is buried. A clear permanent suture, either Prolene or nylon, can be buried deeply in areas of tension. All deep sutures serve to eliminate the dead space and relieve tension from the wound surface. Deep sutures also ensure proper alignment of the wound edges and contribute to their final eversion.
Before placement of the sutures, wound closure may require sharp undermining of the tissues to minimize tension on the wound. Accomplish this maneuver by scalpel or scissors in the subdermal plane. Additionally, achieve hemostasis prior to wound closure to avoid future complications such as hematoma. Use atraumatic skin-handling technique with instruments such as skin hooks and small forceps. Typically, a cutting needle is the needle of choice. Various curvatures are available depending on tissue depth.
For wound closure in the head and neck region, small 5-0 or 6-0 sutures of nonabsorbable Prolene, nylon, or absorbable catgut are appropriate. Take great care to avoid tension during closure. Likewise, avoid strangulation with the suture at the superficial skin level. Take the greatest care to ensure that wound edges are not only aligned but are also everted. Eversion of all skin edges avoids unnecessary depression of the resultant scar. With simple sutures, place knots away from the opposed edges of the wound. Normally, remove nonabsorbable suture after 4-5 days. In certain situations, nonabsorbables can be removed at 10-12 days.
Suturing Techniques
Simple suture or everting interrupted suture
Insert the needle at a 90° angle to the skin within 1-2 mm of the wound edge and in the superficial layer. The needle should exit through the opposite side equidistant to the wound edge and directly opposite the initial insertion. Oppose equal amounts of tissue on each side. A surgeon's knot helps place the nonabsorbable suture. Strive to evert the edges and avoid tension on the skin, while approximating the wound edges. Place all knots on the same side.
Simple running suture
This suture method entails similar technique to the simple suture without a knotted completion after each throw. Precision penetration and tissue opposition is required. The speed of this technique is its hallmark; however, it is associated with excess tension and strangulation at the suture line if too tight, which leads to compromised blood flow to the skin edges. Another variant is the simple locked running suture, which has the same advantages and similar risks. The locked variant allows for greater accuracy in skin alignment. Both styles are easy to remove. Additionally, the running sutures are more watertight.
Mattress suture
Vertical mattress sutures can aid in everting the skin edges. Use this technique also for attachments to a fascial layer. The needle penetrates at 90° to the skin surface near the wound edge and can be placed in deeper layers, either through the dermal or subdermal layers. Exit the needle through the opposite wound edge at the same level, and then turn it to repenetrate that same edge but at a greater distance from the wound edge. The final exit is through the opposing skin edge, again at a greater distance from the wound edge than the original needle entrance site. Place the knot at the surface. A knot placed under tension risks a stitch mark.
The horizontal mattress can be used to oppose skin of different thickness. With this stitch, the entrance and exit sites for the needle are at the same distance from the wound edge. Half-buried mattress sutures are useful at corners. On one side, an intradermal component exists, in which the surface is not penetrated. Place the knot at the skin surface on the opposing edge of the wound.
Subcuticular suture
Sutures can be placed intradermally in either a simple or running fashion. Place the needle horizontally in the dermis, 1-2 mm from the wound edge. Do not pass the needle through the skin surface. The knot is buried in the simple suture, and the technique allows for minimization of tension on the wound edge. In a continuous subcuticular stitch, the suture ends can be taped to the skin surface without knotting.
Complications
Both immediate and delayed complications may occur with wound closure. Immediate complications include the formation of hematoma secondary to improper hemostasis technique and the development of a wound infection. Prophylactic antibiotics have a role in protecting against wound infection. Late complications include scar formation, which may be due to either improper suturing with excess tension or lack of eversion of the edges. Additionally, hypertrophic scarring and keloid formation are unfortunate later complications of wound closure in some individuals. Other complications include stitch marks and wound necrosis.
