This is a modification of the locking horizontal mattress suture, which adds an extra one-half horizontal mattress suture and then is locked through each of the resultant loops. As with many interrupted techniques, it may be used alone for wounds under minimal tension, such as those formed by a small punch biopsy or a traumatic laceration. It is useful in cleft palate repair, and may be used as a transepidermal suture when deeper structures have already been closed. This technique may also be used in the context of atrophic skin, as the broader anchoring bites may help limit tissue tear-through that may be seen with a simple interrupted suture. The double locking variation confers three advantages over the traditional horizontal mattress suture: (1) better ease of suture removal, (2) improved wound-edge apposition, and (3) improved strength under tension.
With all techniques, it is best to use the thinnest suture possible in order to minimize the risk of track marks and foreign-body reactions. Suture choice will depend largely on anatomic location and the goal of suture placement.
On the face and eyelids, though this technique is rarely used, a 6-0 or 7-0 monofilament suture may be used; in these cases, standard horizontal mattress sutures are probably preferable to their locking counterparts. Elsewhere, 5-0 monofilament suture material may be used if there is minimal tension, and 4-0 monofilament suture is used in areas under moderate tension where the goal of suture placement is relieving tension as well as epidermal approximation. In select high-tension areas, 3-0 monofilament suture may be utilized as well.
The needle is inserted perpendicular to the epidermis, approximately one-half the radius of the needle distant to the wound edge. This will allow the needle to exit the wound on the contralateral side at an equal distance from the wound edge by simply following the curvature of the needle.
With a fluid motion of the wrist, the needle is rotated through the dermis, taking the bite wider at the deep margin than at the surface, and the needle tip exits the skin on the contralateral side.
The needle body is grasped with surgical forceps in the left hand, with care being taken to avoid grasping the needle tip, which can be easily dulled by repetitive friction against the surgical forceps. It is gently grasped and pulled upward with the surgical forceps as the body of the needle is released from the needle driver. Alternatively, the needle may be released from the needle driver and the needle driver itself may be used to grasp the needle from the contralateral side of the wound to complete its rotation through its arc, obviating the need for surgical forceps.
The needle is then reloaded in a backhand fashion and inserted at 90 degrees perpendicular to the epidermis proximal (relative to the surgeon) to its exit point on the same side of the incision line as the exit point. Importantly, a loop of suture material is left protruding from where the needle exited on the prior throw to where it enters on this throw.
The needle is rotated through its arc, exiting on the right side of the wound (relative to the surgeon) in a mirror image of steps (2) and (3).
The needle is then reloaded in a standard fashion, and inserted perpendicular to the epidermis proximal (relative to the surgeon) to its exit point on the same side of the incision line as the exit point. Again, a loop of suture material is left protruding from where the needle exited on the prior throw to where it enters on this throw.
The needle is rotated through its arc, exiting on the left side of the wound (relative to the surgeon).
The needle driver is then passed through the first loop and the tail of the suture material is then grasped and gently pulled through the loop, temporarily locking it in place. The tail of the suture material is then released.
The needle driver is then passed through the second loop of suture material, and the needle is grasped with the needle driver and gently pulled through the loop, similarly locking it into place. At this point, both the leading and trailing strands of suture material are on the same side of the incision line.
The suture material is then tied off gently (Figures 5-14A, 5-14B, 5-14C, 5-14D, 5-14E, 5-14F, 5-14G, 5-14H, 5-14I, 5-14J).