Chapter 5.18: The Locking Vertical Mattress Suture

Loop mattress suture

This technique, also known as the loop mattress suture, is a locking variation of the vertical mattress suture that may be used for closure and epidermal approximation. Unlike the standard vertical mattress suture, this technique adds a section of suture crossing over top of the incised wound edge, which may be useful to aid in wound-edge apposition. As with many interrupted techniques, it may be used alone for wounds under modest tension, such as those formed by either a small punch biopsy or a traumatic laceration.

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, 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. When the goal of the locking vertical 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 may be used if there is minimal tension, and 4-0 monofilament suture is useful 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.

1. The needle is inserted perpendicular to the epidermis, approximately 6 mm distant from the wound edge.

2. With a fluid motion of the wrist, the needle is rotated deep through the dermis, and the needle tip exits the skin on the contralateral side. If the needle radius is too small to complete this arc in one movement, this first step may be divided into two, with the needle first exiting between the incised wound edges and then reloaded and reinserted to exit on the contralateral side.

3. 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.

4. The needle is then reloaded in a backhand fashion and inserted at 90 degrees perpendicular to the epidermis approximately 3 mm from the wound edge on the same side of the incision line as the exit point.

5. The needle is rotated superficially through its arc, exiting on the contralateral side of the wound 3 mm from the incised wound edge. Suture material is not pulled tight, however, and a loop of suture, formed by the exit of the suture material laterally and its reentry medially, is left in place.

6. In order to lock the suture over top of the wound, the needle is passed through the loop formed by the exit and entry of suture material on the contralateral side.

7. 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 5-18A, 5-18B, 5-18C, 5-18D, 5-18E, 5-18F).

This approach may be conceptualized as a hybrid between a vertical mattress suture, a simple interrupted suture, and a pulley suture. Like the vertical mattress suture, this technique leads to pronounced wound-edge eversion. Like the simple interrupted suture, this approach affords excellent wound-edge approximation. And like the pulley suture, the multiple loops lead to a reduction in needed tension across the suture material.

As with most transepidermal techniques, it is important to enter the epidermis at 90 degrees, following the curvature of the needle when utilizing this technique. This will allow for maximal wound eversion and accurate wound-edge approximation.

As with the simple interrupted suture, care should be taken to avoid skimming the needle superficially beneath the epidermis. This results from failing to enter the skin at a perpendicular angle and to follow the curvature of the needle. This may result in wound inversion as the tension vector of the shallow bite pulls the wound edges outward and down.

Note that the second throw is placed superficial to the first, deeper far-far suture, leading to a nested placement of the suture material. This leads to both wound eversion as well as wound-edge approximation, and the final loop of suture material traversing the incised wound edge permits the wound edges to be precisely matched.

Before forming the final locking loop, it is helpful to pull through the bulk of the suture material, leaving only a modest tail and a small residual loop. This will help reduce the risk of the suture material tangling during pull through.

This technique ideally results in an everted wound with excellent wound-edge apposition due to the presence of the locking loop over the surface of the incised wound edge. In practice, the locking step may lead to wound-edge inversion, and therefore this approach should be used selectively.

With any suturing technique, knowledge of the relevant anatomy is critical. When placing a vertical mattress suture it is important to recall that the structures deep to the epidermis may be compromised by the passage of the needle and suture material, or that constriction may take place. That said, the vertical orientation of this approach helps minimize this risk.

This technique may elicit an increased risk of track marks, necrosis, and other complications when compared with techniques that do not entail suture material traversing the scar line, such as buried or subcuticular approaches. Therefore, sutures should be removed as early as possible to minimize these complications, and consideration should be given to adopting other closure techniques in the event that sutures will not be able to be removed in a timely fashion.