Suturing continues to be the most common method for laceration repair in the ED and percutaneous sutures that pass through both the epidermal and dermal layers are the type most frequently used. Dermal, or subcuticular, sutures reapproximate the divided edges of the dermis without penetrating the epidermis. Occasionally, dermal and percutaneous sutures are used together in a layered closure. As noted above, dermal sutures can be used with either surgical tapes or tissue adhesives for epidermal closure. Sutures can be applied in a continuous manner ("running," with knots at each end of a long closure) or as interrupted sutures (each loop being individually tied).
Monofilament nylon or polypropylene sutures are most commonly used for skin closure because these materials have acceptable mechanical properties and low tissue reaction. Polybutester sutures have unique performance characteristics that may be advantageous for the closure of wounds that might expand from edema and then contract as the swelling resolves. Polybutester can elongate in response to low forces and has elasticity, enabling it to return to its original length once the load is removed. Sutures with less extensibility under low forces—like nylon, polypropylene, polyester, or silk—will frequently lacerate or necrose encircled tissue in edematous wounds, thereby increasing the susceptibility to infection.
Percutaneous sutures are recommended for closure of stellate lacerations resulting from crush injuries. In these wounds, meticulous closure with percutaneous sutures approximates the skin edges more exactly than does tape. Closing these wounds is often like putting together a jigsaw puzzle, and tapes have little practical value. The more accurate approximation of skin edges by skillfully applied sutures leads to a more pleasing cosmetic result. Damage to the local tissue defenses is related to the quantity of the suture within the wound (diameter and length); therefore, the suture with the narrowest diameter and sufficient strength to resist disruption of the closure should be used.
Straight, shallow lacerations can be closed with percutaneous sutures only, sewing from one end toward the other and aligning edges with each individual suture bite. Deep, irregular wounds with uneven, unaligned, or gaping edges are more difficult to suture. Certain principles have been identified by years of clinical experience:
1. The uneven edges can be aligned by first approximating the midportion of the wound with the initial suture. Subsequent sutures are placed in the middle of each half, and so on, until the wound edges are aligned and closed.
2. Wounds where the edges cannot be brought together without excessive tension should have dermal sutures placed to close the gap partially and reduce the force on the epidermal closure.
3. Adipose tissue beneath the skin should not be sutured; obliteration of this potential dead space between the cut edge of adipose tissue by even the least reactive suture increases the incidence of infection.
4. When wounds of different thickness are to be reunited, the needle should be passed through one side of the wound and then drawn out before reentry through the other side. This maneuver ensures that the needle is inserted at comparable levels on each side of the wound. Unless appropriate adjustment of the bite is made on the thinner side, uneven coaptation of the skin will occur, resulting in a step-off scar.
Dermal sutures can be used alone or as adjuncts to percutaneous sutures in wounds subjected to strong skin tensions, to serve as an added precaution against disruption of the wound. Some physicians prefer a synthetic absorbable suture for dermal closure, while others favor a synthetic nonabsorbable suture. The nonabsorbable suture is applied in a continuous manner with the ends brought out the skin and secured at both ends of the wound. This suture can then be removed before the eighth day after wound closure to prevent the development of needle puncture scars. When dermal closure alone is used, it is advisable to close the skin with surgical tapes or tissue adhesive for more accurate approximation of the epidermis.
In clean wounds (e.g., elective surgical incisions), subcutaneous sutures do not significantly increase the incidence of wound infection. However, in traumatic wounds, particularly with contamination, dermal sutures potentate wound infection.16 Once an infection develops, the collecting purulent exudate spreads preferentially between the divided edges of fat rather than penetrating the closed dermis. By the time the infection becomes clinically apparent, it has usually involved the entire extent of the wound. One value of dermal closure is thought to be that by reducing tension across the wound, scar width will be lessened. However, despite the immediate, esthetically pleasing appearance of dermal skin closure, it does not improve the ultimate cosmetic appearance of the healing wound; scar width after dermal skin closure is comparable to the scar width of wounds healing in the absence of dermal sutures. Another effective method of reducing tension during closure is to undermine the skin edges. However, this benefit must be weighed against the potential damage to the skin blood supply, which may compromise the host's defenses and invite infection. Consequently, undermining of the wound edges of lacerations should be done in carefully selected situations in the ED.
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