This is a modification of the horizontal mattress suture, a frequently used everting technique used for closure and epidermal approximation. 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 also frequently used as a secondary layer to aid in everting the wound edges when the dermis has been closed using a deep suturing technique. This technique may also be used in the context of atrophic skin, as the broader anchoring bites may help limit the tissue tear-through that may be seen with a simple interrupted suture. This locking variation confers two advantages over the traditional horizontal mattress suture: better ease of suture removal and improved wound-edge apposition.
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. Locking horizontal mattress sutures may be placed with the goal of: (1) effecting eversion, or (2) adding an additional layer of closure for wound stability and dead-space minimization.
On the face, a 6-0 or 7-0 monofilament suture may be used, though fast-absorbing gut may be used on the eyelids and ears to obviate the need for suture removal; in these cases, standard horizontal mattress sutures are probably preferable to their locking counterparts. When the goal of the horizontal mattress suture placement is solely to encourage wound-edge eversion, fine-gauge suture material may be used on the extremities as well. Otherwise, 5-0 monofilament suture material is useful if there is minimal tension, and 4-0 monofilament suture maybe 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 the wound 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 passed under the loop of suture material on the contralateral side.
The suture material is then tied off gently, with care being taken to minimize tension across the epidermis and avoid overly constricting the wound edges (Figures 5-6A, 5-6B, 5-6C, 5-6D, 5-6E, 5-6F).