Chapter 4.32: The Percutaneous Purse-String Suture

As with the buried purse-string closure, this technique is designed to use circumferential tissue advancement 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. This percutaneous approach is most useful either for relatively narrow wounds or those with marked atrophy of the surrounding skin, such as on the shins and scalp.

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 extremities and scalp, where this technique is generally used, a 3-0 or 4-0 absorbable suture material may be used. On the back and shoulders, 2-0 or 3-0 suture material is effective. Since the technique requires easy pull through of suture material, monofilament absorbable suture is generally preferable.

1. At the wound edge at the far end of the round- or oval-shaped wound, the needle is inserted at 90 degrees through the epidermis parallel to the incision line 5-20 mm set-back from the wound edge. Alternatively, if absorbable suture material is used, the needle may enter from the underside of the dermis so that the final knot will be buried.

2. The curvature of the needle is followed keeping the same distance from the wound edge so that the needle exits through the epidermis 10-15 mm to the left of the entry point at the same distance set-back from the wound edge by following a trajectory running parallel to the incision. Bite size is dependent on needle size. 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 steps (1) through (3). With each throw, however, the needle pierces the epidermis through the exit hole of the prior throw.

4. A small amount of suture material is pulled through with each throw.

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

6. The suture material is then pulled taut, leading to complete or partial closure of the wound, and tied utilizing an instrument tie (Figures 4-32A, 4-32B, 4-32C, 4-32D, 4-32E, 4-32F, 4-32G).

Unlike the fully buried purse-string approach, this technique allows for additional recruitment of the surrounding tissue by permitting placement of the sutures markedly set-back from the wound edge. This may therefore be a technique of choice if maximal tension is expected on the wound.

This variation may also be useful when the wound is relatively narrow, such as on the shin, or when the skin is very atrophic and the full thickness of the dermis needs to be recruited to provide stability and minimize suture tear through.

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.

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.

The knot may be buried by beginning and ending this technique on the interior of the wound (as opposed to starting outside the skin), although the tension across the knot generally pulls it inward if the standard technique is used and the suture line is started on the exterior of the skin.

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.

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.

Utilizing the same holes for exit and entry of the needle is designed to minimize residual skin dimpling, but increases the risk that the suture material will be cut by the needle as it renters the same hole. Since the entire closure rests on the resiliency of a single strand of suture, this risk should not be overlooked. A simple variation of this technique, where the needle is reinserted through a hole just lateral to the exit point, may help mitigate this potential risk.

Skin dimpling is often seen with this approach, particularly since these wounds are often closed under significant tension. This does generally resolve with time, but patients should be warned to expect these changes in the immediate postoperative period.

As with the buried purse-string closure, 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.

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 that would traditionally be executed.

While arguable better than the fully buried purse-string closure, 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.