Chapter 4.6: The Running Subcuticular Suture

This is an epidermal approximation technique suitable for wounds under minimal to no tension. This technique should almost never be employed in the absence of a deep dermal suture, since its strength is in fine-tuning epidermal approximation and it is less effective in the presence of significant tension. Its use is also predicated on the presence of a relatively robust dermis, since it is a primarily intradermal technique and therefore does not recruit any strength from the epidermis. Therefore, it should be avoided in the context of atrophic skin or in areas with a very thin dermis, such as the eyelids.

As with any technique, it is best to utilize the thinnest suture possible for any given anatomic location. The subcuticular suture technique is not designed to hold tension irrespective of anatomic location. Since its utility is limited to fine-tuning epidermal approximation, 5-0 or 6-0 suture is often useful when adopting this technique.

Depending on the chosen technique variation, this technique may be used with either absorbable to nonabsorbable suture. If nonabsorbable suture is used, it is best to utilize a monofilament suture material to minimize the coefficient of friction when removing the suture. Since a relatively large amount of suture material will be left in the superficial dermis, if absorbable material is used then utilizing a nonbraided monofilament suture may be best to minimize the risk of infection and foreign body reaction.

1. The needle is inserted at the far right corner of the wound, parallel to the incision line, beginning approximately 2-5 mm from the apex. The needle is passed from this point, which is lateral to the incision apex, directly through the epidermis, exiting into the interior of the wound just medial to the apex. Note that this first pass may be finessed depending on the technique used for finishing the closure, as addressed in detail below.

2. With the tail of the suture material resting lateral to the incision apex and outside the wound, the wound edge is gently reflected back and the needle is inserted into the dermis on the far edge of the wound with a trajectory running parallel to the incision line. The needle, and therefore the suture, should pass through the 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 above step on the contralateral edge of the incised wound edge.

4. A small amount of suture material is pulled through, the skin of the contralateral wound edge is reflected back, and the needle is inserted into the dermis on the contralateral side of the incised wound edge and the same movement is repeated. The needle should enter slightly proximal (relative to the wound apex where the suture line began) to the exit point, thus introducing a small degree of backtracking to the snake-like flow of the suture material. This will help reduce the risk of tissue bunching.

5. The same technique is repeated on the contralateral side until the end of the wound is reached. At this point, the needle is inserted from the interior of the wound in line with the incision line and exits just lateral to the apex of the wound (Figures 4-6A, 4-6B, 4-6C, 4-6D, 4-6E, 4-6F, 4-6G, 4-6H, 4-6I, 4-6J).

Body positioning can be very helpful in maintaining an efficient and comfortable subcuticular technique. Most surgeons are trained to work with the surgical site flat and perpendicular to their body. Since the motions associated with subcuticular suture placement are 90 degrees off from this, it may be useful to stand with the surgeon's body (shoulder to shoulder) parallel to the incision line. This allows for a flowing motion from right to left without the need to twist the shoulders or wrists.

One of the classic conundra relating to this technique is how to start and finish the closure; there are myriad options available to the surgeon. Some of the available options for finishing this suture include the following:

1. Clipping the ends of the suture at the level of the epidermis: This technique is of maximal convenience to surgeon and patient and minimizes the risk of leaving any track marks whatsoever. Since the ends of the suture are not tacked down in any way, however, it does not have the potential to hold the epidermis in place in the face of stress. This is particularly true if an absorbable monofilament suture is used, as it can easily slip through the dermis, and will naturally slip away from the areas under most tension.

2. Clipping the ends of the suture after leaving a long (3-6 cm) tail: The tails may be tacked down with adhesive strips, tissue glue, or surgical tape to minimize slippage over time. This approach is most suited if nonabsorbable monofilament will be used, as it may be left in place for 6 weeks or more. If the suture tails are not fixed in place, this may lead to some surface irritation where the suture material exits lateral to the apices of the wound.

3. Tying a single buried dermal suture or set-back dermal suture at each end of the running subcuticular loop: The first dermal suture is tied at the far end and the end of the suture is trimmed either at the knot or slightly above the knot. The running subcuticular technique is then executed as noted earlier and a similar knot is tied at the other end. In this case, the first and last throws of suture do not begin and end outside of the wound (as outlined previously), but rather as dermal sutures at the apices of the repair.

4. The ends of the suture may be tied to each other in a bow over the top of the wound: This requires leaving sufficient laxity at the beginning as well as pulling through sufficient suture material so that the bow may be tied at approximately the center point of the wound. Risks associated with this approach include torque-induced tissue damage at the apices where the suture material exits the wound as well as the risk that the loose bow may be pulled by the dressing or an inattentive patient.

Attempting to execute this technique with fewer dermal bites occasionally results in crimping of the epidermis as the wound edges pleat together. This may be avoided by setting back each bite of the dermis slightly relative to the apex so that the pattern the suture makes in the dermis consists of wider U-shaped bites moving in a serpiginous pattern. Assiduous attention to detail in taking a sufficient number of bites should effectively mitigate the risk of epidermal crimping.

A smooth, flowing technique is of paramount importance in executing this technique effectively and efficiently. Some authors have advocated adjusting the angle used to hold the needle in the needle driver from the traditional 90 degrees to 135 degrees to increase the surgeon’s comfort and minimize the need for physical contortion, though slightly adjusting the surgeon’s body position helps significantly in this regard and obviates the need to adjust the needle loading angle.

While a central strength of the running subcuticular suture is its entirely intradermal placement, this may also represent one of its greatest drawbacks. This technique results in leaving a significant quantity of foreign-body material in the dermis in a continuous fashion. While this may not represent a major problem in areas with a thick dermis such as the back, in other anatomical locations the large quantity of suture that is left in situ may result in concerns regarding infection, foreign-body reaction, and even the potential that the suture material itself could present a physical barrier that would impinge on the ability of the wound to heal appropriately—essentially an iatrogenic eschar phenomenon.

A similar concern relates to leaving a suture tunnel if nonabsorbable suture material is used and is then removed after a period of time. As one of the benefits of this approach is to permit the suture to remain in place for many weeks or months, it also means that removal of long-standing suture entails a theoretical risk that a potential space—albeit a thin and long one—is created on the removal of the suture material. Again, this theoretical risk may be mitigated by utilizing the thinnest possible suture material.

If nonabsorbable suture material is used, care should be taken to account for the eventual necessity of suture removal. Since the nonabsorbable monofilament will be removed by applying a continuous gentle pull on the free edge of the suture, it is imperative that the length of the continuous suture be kept to a reasonable maximum, to avoid the risk of suture snapping mid pull. In cases where a longer wound is closed using nonabsorbable suture material, a single simple interrupted suture may be placed as part of the course of the suture material every 4 cm or so, providing a site where the suture material may be snipped and pulled through at the time of suture removal.

In the event that slow-absorbing absorbable suture is used, consideration should be given to utilizing undyed suture material, since depending on the depth of suture placement and the degree of epidermal atrophy the suture material may sometimes remain visible.

Depending on the placement of the deep sutures, it is possible for this technique to lead to some mild inversion of the epidermal edges as they are pulled inward by the suture material. This is particularly the case when the suture is finished with a fixed knot holding the ends of the suture material in a fixed position.