CHAPTER 2 Principles of Wound Closure
BACKGROUND
Normal wound healing progresses through three distinct but overlapping phases. The inflammatory phase of wound healing begins first and lasts between 3 and 7 days in the normal wound environment; the presence of significant devitalized tissue (e.g., in traumatic wounds) can prolong this phase. The inflammatory phase is characterized by the influx of neutrophils and macrophages. The proliferative phase of wound healing typically begins after 24 hours and may last for up to 3 weeks. The hallmark of the proliferative phase is the formation of granulation tissue, a dense network of fibroblasts, extracellular matrix, and newly formed blood vessels. The principal cell types involved in the proliferative phase are the keratinocyte and the fibroblast. The remodeling phase of wound healing begins after 2 weeks and may last as long as 1 year. In the remodeling phase, the wound begins to contract and the collagen present in the wound is reorganized. The principal cell type involved in wound contracture is the myofibroblast, whereas fibroblasts are responsible for depositing and reorganizing collagen (Fig. 2-1).
WOUND CLOSURE
Suture Materials
I. Suture Size: Suture material is available in a variety of sizes. Sutures were originally manufactured in sizes ranging from #6 to #1, with #6 being the largest. As manufacturing techniques improved, #0 suture was introduced. Subsequently, smaller sizes were introduced and named according to the number of zeros they contained (i.e., 00 = 2-0, 000 = 3-0, etc.). The size of suture should reflect the application and the amount of tension on the wound. In general, the finest suture material that will maintain the approximation of tissues should be used.
II. Absorbable versus Nonabsorbable: A variety of permanent and absorbable suture materials are commonly available. In general, the suture material used should not absorb until the inherent tensile strength of the wound is sufficient to maintain tissue approximation. Tissues that take longer to heal (e.g., tendons or fascia) should be reapproximated with longer-lasting suture material. Skin, on the other hand, heals quickly and may be closed with rapidly absorbable suture material.
III. Braided versus Monofilament: Both absorbable and nonabsorbable suture materials are available in single-strand (monofilament) and braided varieties. The choice of which to use is often determined by surgeon preference. Braided suture tends to be easier to tie compared with monofilament suture; however, braided suture may cause a more substantial local tissue reaction, resulting in delayed healing.
IV. Needle Type: Suture material may be swedged onto needles of a variety of types and sizes to suit specific applications. The two most common needle types are tapered and cutting. Cutting needles have two sharp cutting edges. These needles are commonly used to place sutures into the skin because they make penetration easier. Tapered needles are round in cross-section and pass through tissue in a less traumatic fashion.
Suturing Techniques
I. Simple Interrupted: The simple interrupted suture is among the most commonly used techniques; a limitation is that dermal apposition may be difficult to achieve.
II. Vertical Mattress: The vertical mattress technique is commonly used to approximate tissues that are under tension. An advantage of the vertical mattress suture is that excellent dermal apposition is achieved without compromising the vascularity of the skin edges.
III. Horizontal Mattress: Like the vertical mattress suture, the horizontal mattress technique affords excellent dermal apposition; however, the horizontal mattress technique may result in a greater degree of wound ischemia compared with the vertical mattress technique.
IV. Subcuticular: This running stitch is buried in the superficial dermis and is used to closely reapproximate the epidermis.
V. Over-and-Over (“baseball stitch”): This technique may be used to close large incisions rapidly; the limitations are similar to those associated with simple interrupted sutures (i.e., poor dermal apposition). In addition, over-and-over sutures can compromise skin edge vascularity.
VI. Skin Staples: Surgical staples close large wounds efficiently and are commonly used after abdominal procedures. An advantage of stapled closure is that individual staples may be removed when a wound becomes infected without interrupting the remaining closure.
VII. Skin Glue/Tape: Skin glue (i.e., Dermabond) and skin tapes (Steri-Strips) can be used to approximate dermal lacerations that are not under significant tension or as an adjunct to other techniques (Fig. 2-2).
Alternative Closure Techniques
I. Local Skin Flaps: A flap is defined as transposed tissue with an intact blood supply. Skin flaps use laxity in adjacent tissues to redistribute wound tension over a larger area. Skin flaps may be rotated or advanced to cover a wound (Fig. 2-3).
II. Skin Grafts: Skin grafting involves the harvest of skin from a donor site to cover a wound (i.e., the recipient bed). Because skin grafts rely on revascularation, an appropriate recipient bed is an important prerequisite for graft “take.” Skin grafts will not survive in the presence of infection, ongoing trauma, or poor recipient site vascularity. The size of the wound that requires coverage and the availability of donor tissues determine whether a split-thickness or full-thickness graft is used.
A. Split-thickness skin grafting involves the harvest of epidermis and partial-thickness dermis from a donor site (commonly the thigh or buttocks). The donor site subsequently re-epithelializes from the dermal elements that remain. Split-thickness grafts may be meshed to allow greater expansion of the graft and coverage of a larger area; however, a disadvantage of split-thickness grafts is the significant amount of graft contracture seen postoperatively.
B. Full–thickness skin grafting involves harvest of the full epidermis and dermis. Full-thickness skin graft donor sites are typically closed primarily. Generally, full-thickness grafts are used to cover small wounds. Compared with split-thickness grafts, full-thickness grafts undergo little postoperative contraction.
POSTOPERATIVE CONSIDERATIONS: SURGICAL DRESSINGS
A variety of dressing types may be used in the management of surgical wounds.
I. Simple dry dressings serve to protect a wound from infection and absorb wound drainage. They are commonly applied to closed wounds. Semipermeable, nonpermeable, hydrogel, and hydrocolloid dressings maintain a moist environment and may facilitate healing of wounds that heal by epithelialization (e.g., skin graft donor sites).
II. Wet-to-dry dressings are commonly used to dress open and contaminated wounds; mechanical debridement of the wound results from removal of dried packing material with adherent devitalized tissue. Enzymatic agents (e.g., papain/urea [Accuzyme]) may be used in conjunction with dressings to gently debride fibrinous debris. In addition, application of broad-spectrum antibacterials (e.g., silver sulfadiazine) may limit bacterial colonization and promote wound healing.
III. Recently, VAC dressings have gained great popularity for the management of open wounds. The VAC dressing has three components: (1) the VAC sponge, which is applied directly to the wound bed; (2) an occlusive dressing, which is applied over the sponge to seal it to the surrounding skin; and (3) a suction pump, which provides regulated negative pressure through the sponge. The VAC has been used extensively to promote granulation tissue formation and wound contraction. A major advantage of the VAC is the need for fewer dressing changes compared with conventional dressings (Fig. 2-4).
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Lee CK, Hansen SL. Management of acute wounds. Clin Plast Surg. 2007;34:685-696.
Thorne CH, Beasley RW, Aston SJ, et al. Grabb and Smith’s Plastic Surgery, 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2007.
