Chapter 4.14: The Running Percutaneous Set-Back Dermal Suture

Running percutaneous Kantor suture

This is a niche technique appropriate for the closure of narrow wounds under modest tension. In anatomic locations such as the scalp and lower leg, there is often insufficient laxity to permit effective visualization of the undersurface of the undermined wound edge that would be ideal for the placement of running set-back dermal sutures.

Since this is a running technique, it may be associated with a higher risk of dehiscence, as interruption of the suture material in any point in its course or of one of the knots would lead to loss of effectiveness of the entire suture line.

On the scalp, a 3-0 or 4-0 absorbable suture is probably best, as it allows for robust closure in this area where tension is occasionally moderate to severe. On the lower legs, 3-0 or 4-0 absorbable suture material may be used as well, as this area is sometimes under marked tension. As always, utilizing the smallest gauge suture material that will permit adequate closure under tension is best.

1. If possible, the wound edge is reflected back using surgical forceps or hooks. Adequate visualization of the underside of the dermis is not required.

2. While gently grasping the skin edge, the suture needle is inserted at 90 degrees into the underside of the dermis 2-4 mm distant from the incised wound edge.

3. The first bite is executed by traversing the dermis and piercing directly up through the epidermis, with the needle exiting the epidermis 2-4 mm from the incised wound edge.

4. The needle is then reloaded on the needle driver in a backhand fashion and inserted at 90 degrees just medial to the exit point. The needle exits the undermined surface of the dermis into the undermined space between the undersurface of the dermis and the deeper subcutaneous tissue.

5. The needle is then reloaded, again in a backhand fashion, and inserted into the undersurface of the dermis on the contralateral wound edge, 2-4 mm distant from the incised wound edge. Depending on needle size and the breadth of the wound, this step may be combined with the prior step, saving the need to reload the needle. The needle should traverse the dermis and exit through the epidermis 2-4 mm distant from the incised wound edge.

6. The needle is then reloaded in a standard fashion and inserted in the epidermis just lateral to the exit point at 90 degrees, exiting the undersurface of the dermis in the undermined space.

7. The suture material is then tied utilizing an instrument tie, and the trailing end of the suture is trimmed.

8. Moving proximally toward the surgeon, steps (1) through (6) are then repeated in pairs; once the desired number of throws are placed, the suture material is then tied off in a secure fashion utilizing an instrument tie (Figures 4-14A, 4-14B, 4-14C, 4-14D, 4-14E, 4-14F, 4-14G, 4-14H, 4-14I, 4-14J). The final anchoring knot is tied by leaving a loop on the penultimate throw, and tying the free end of suture material from the final throw to this loop. The ends of the suture are then trimmed.

As noted previously, this is an infrequently utilized approach, and is best for closing areas under mild to moderate tension when other running approaches are not feasible. Since knots are tied only at the beginning and the end of the entire line of sutures, this technique is faster than utilizing standard interrupted percutaneous set-back dermal sutures, though this benefit must be weighed against the increased risk of suture line compromise with this approach.

It is critical to focus on outstanding knot security, since the entire suture line is held in place by the knots at the beginning and end of the set of suture throws. Adding an additional tacking knot when utilizing this approach is an option as well. It may provide additional knot security. Alternatively, one could consider placing an additional knot or leaving a longer suture tail.

Although it requires utilizing a backhand technique, this approach may be easier than other running buried techniques, since the suture pierces the epidermis and dermis at a 90 degree angle there is no need to change planes or guarantee that the suture exit point is precisely at the inside edge of the lower dermis.

This approach may also be used in wounds under modest tension where extensive undermining is not possible; since the undersurface of the dermis does not need to be visualized to effectively place the sutures, the throws can be essentially placed blindly.

This technique may be conceptualized as a largely buried alternative to the simple running closure, since both approaches do not require wide undermining or an easily reflected wound edge and both approaches may be utilized in areas under modest tension.

An important theoretical advantage of this approach over other running percutaneous approaches is that no suture material is left between the wound edges. Since even absorbable suture material may represent a physical impediment to wound healing, this is an important benefit that this approach shares with the percutaneous and standard set-back dermal suture techniques.

Another theoretical benefit of the running approach is that there is less suture material left in situ, since the bulk of retained absorbable suture material is in the knots; as there are knots only at the beginning and end of the row of sutures, this technique theoretically decreases the risk of suture spitting and suture abscess formation. Still, the standard running set-back approach leaves suture material deep to the undersurface of the dermis, and therefore the risk of suture spitting and suture abscess formation is negligible.

Like the interrupted percutaneous set-back dermal suture, the running percutaneous set-back dermal approach may result in very dramatic wound eversion, and the degree of eversion elicited by this approach may be more marked than that seen with the standard set-back dermal suture approach. This pronounced eversion may lead the epidermal portion of the wound edges to separate as the dermis is brought together, as the epidermal edges fail to drape together as they would normally do with the standard set-back dermal technique.

There are two possible approaches to this situation: (1) Superficial running or interrupted sutures may be placed to better approximate the epidermal edges; and (2) The defect could be initially excised with an inward bevel (as is done with the butterfly suture technique), or the dermis may be incised at an inward bevel after the original defect is created, permitting the epidermal edges to come together gently even in the face of the marked eversion seen with this approach. Many clinicians favor a bilayered approach in general, and therefore placing the epidermal sutures is an easy approach and does not require the degree of preplanning associated with the bevel approach, though a combination of the two solutions may be utilized as well. Since the running percutaneous set-back dermal approach relies on the security of only two knots to stabilize the entire length of the wound, placing simple interrupted epidermal sutures may be worthwhile.

Patients should be cautioned that they might develop a significant ridge in the immediate post-operative period. Depending on the suture material used and the density of the sutures, this ridge may last from weeks to months.

Epidermal dimpling will often occur with this approach, since the suture material traverses the epidermis. A small degree of dimpling will resolve with time as the absorbable sutures are gradually resorbed, and patients should be warned that this is a likely occurrence and that it is of no long-term clinical consequence.

Since suture material traverses the epidermis, there is a theoretically greater risk of infection with this technique than with approaches that remain entirely buried on the undersurface of the dermis. Meticulous attention to sterile technique may help mitigate this theoretical risk, and anecdotally infection is seen no more frequently with this approach than with any other closure technique.