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.
If possible, the wound edge is reflected back using surgical forceps or hooks. Adequate visualization of the underside of the dermis is not required.
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.
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.
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.
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.
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.
The suture material is then tied utilizing an instrument tie, and the trailing end of the suture is trimmed.
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.