Chapter 4.31: The Buried Purse-String Suture

This technique is designed to either shrink the size of a defect or obviate it entirely, depending on the degree of tension and the size of the defect. It is a niche technique, since the purse-string effect tends to lead to a slight puckering in the surrounding skin, a feature that may be acceptable (and will likely resolve with time) on areas such as the forearms and back but is less desirable in cosmetically sensitive locations such as the face. The running nature of the technique means that compromise at any point in the course of suture placement may result in wound dehiscence, though for this reason a larger gauge suture material is generally utilized.

Suture choice is dependent in large part on location, though as always the smallest gauge suture material appropriate for the anatomic location should be utilized. On the back and shoulders, 2-0 or 3-0 suture material is effective, and on the extremities and scalp, a 3-0 or 4-0 absorbable suture material may be used. When used on the face, a 5-0 absorbable suture is adequate. Since the technique requires easy pull through of suture material, monofilament absorbable suture is generally preferable.

1. The wound edge at the far end of the round- or oval-shaped wound, parallel to the incision line, is reflected back.

2. With the tail of the suture material resting between the surgeon and the far end of the wound, the needle is inserted into the underside of the dermis on the far edge of the wound with a trajectory running parallel to the incision. Generally, this entry point in the dermis should be approximately 3-6 mm set-back from the epidermal edge, depending on the thickness of the dermis and the anticipated degree of tension across the closure. The needle, and therefore the suture, should pass through the deep dermis at a uniform depth. Bite size is dependent on needle size, though in order to minimize the risk of necrosis it may be prudent to restrict the size of each bite. The needle should exit the dermis at a point equidistant from the cut edge from where it entered.

3. The needle is then grasped with the surgical pickups and simultaneously released by the hand holding the needle driver. As the needle is freed from the tissue with the pickups, the needle is grasped again by the needle driver in an appropriate position to repeat the preceding step to the left of the previously placed suture.

4. A small amount of suture material is pulled through and the needle is inserted into the dermis to the left of the previously placed suture, and the same movement is repeated.

5. The same technique is repeated moving stepwise around the entire wound until the needle exits close to the original entry point at the far end of the wound.

6. Once the desired number of throws have been placed, the suture material is then pulled taut, leading to complete or partial closure of the wound, and tied utilizing an instrument tie (Figures 4-31A, 4-31B, 4-31C, 4-31D, 4-31E, 4-31F).

This technique is designed as an efficient method of wound area reduction. In many cases, placing a purse-string suture can effect complete wound closure and it therefore represents an alternative to a layered repair of a fusiform incision.

It has been suggested that some defects on the back and extremities, particularly in elderly patients with loose skin, are better closed with a purse-string approach than with a traditional linear closure, since linear closures often heal with a residual scar and require a significantly longer excision line, while the puckering that may be present immediately postoperatively with purse-string closures is likely to resolve with time. That said, in the right hands linear closures on the trunk and extremities often heal with subtle scarring, even when wounds are closed under tension.

On a pragmatic level, this approach is generally utilized when either a patient is unwilling to undergo a traditional linear closure or when their comorbidities make the additional length of the incision for a linear closure an unrealistic option.

As with linear running dermal techniques, this technique may be used as a modified winch or pulley suture, since the multiple loops help minimize the tension across any one loop and permit closure of wounds under marked tension. Because each throw is not tied off, however, it is important to adequately secure the knot.

Tying a purse-string closure under significant tension may be challenging, as suture material tends to slip after the first knot throw. Utilizing hemostats to secure the suture ends in position during suture lockdown may help mitigate this problem.

Absorbable purse-string sutures may also be used to reduce the size of a defect prior to graft placement, in a fashion similar to the guitar string suture.

As with other running dermal techniques, this approach leaves a fair amount of absorbable suture material in the dermis. Therefore, foreign-body reactions, suture abscess formation, and infection are possibilities. The entire suture line is secured with a single knot, and since most of the bulk of any suture line is in the knots, rather than the lengths of suture material between knots, this technique may be less susceptible to suture abscess or suture spitting than others.

The pucker effect of this closure resolves rapidly in atrophic skin, though it can persist in other areas; patients should realize that some degree of residual puckering toward the center of the wound is to be expected. Additionally, this technique may be used to help recreate the nipple-areola complex if full reconstruction is not desired and the nipple is lost to a local tumor.

Since the entire closure is held by a single knot, this approach may be associated with a higher rate of wound dehiscence, as knot failure or failure in the suture material at any point leads to an immediate loss of tension on the closure. Given the concern regarding knot breakage, it may be helpful to attempt to better secure the knot. This may be done by paying particularly close attention to knot tying, tying an extra full knot, adding extra throws, or leaving a longer tail than would traditionally be executed.

A recent study has suggested, however, that the postoperative cosmesis of a purse-string closure is no better than a wound allowed to heal with secondary intention healing though wounds closed with purse-string sutures may heal approximately two weeks faster than those allowed to heal by secondary intention.

This approach provides less wound eversion than vertically oriented approaches such as the set-back dermal or buried vertical mattress sutures. Therefore, consideration should be given to adding additional superficially placed everting sutures, such as the vertical mattress suture, in order to mitigate this problem. Still, since this approach is generally adopted when the surgeon has accepted that the cosmetic outcome may be less than ideal, it may be reasonable to use this approach as a solitary closure.