Suturing Techniques

Everted wound edges (edges that protrude slightly above the surrounding skin) are essential for optimal scar formation. During wound maturation, the elevated edges settle and flatten to become level with the surrounding skin, producing a flat, cosmetically acceptable scar. Wound edges that are flat at closure will contract and become depressed (inverted) during healing, creating a pitted scar that is far more conspicuous. Eversion is achieved through: (1) proper buried suture placement that pushes tissue upward, (2) vertical mattress sutures that mechanically evert edges, and (3) the natural tendency of tissue to evert when undermining is adequate and tension is properly distributed.

Undermining is the separation of tissue planes adjacent to the wound to recruit additional tissue laxity and reduce closure tension. It is essential for most excisional wounds beyond the smallest closures. Plane of undermining varies by location: on the face, undermine within the subcutaneous fat, superficial to the muscular aponeurotic system (SMAS). On the trunk and extremities, undermine within the subcutaneous fat above the fascia. On the scalp, undermine in the subgaleal (loose areolar) plane, which allows maximal tissue movement. Extent: typically 1–2 cm beyond each wound edge for standard excisions. Larger undermining may be needed for high-tension closures. The goal is to reduce wound edge tension enough that deep sutures can approximate without strangulation.

The buried vertical mattress (BVM) is THE cornerstone suture of dermatologic surgery. It is placed with the knot buried (inverted) in the deep tissue, preventing knot extrusion and foreign body reaction at the wound surface. Technique: Enter the deep dermis or dermis-subcutis junction from within the wound on one side. Travel through the subcutaneous tissue (the needle arc should be wider deep than at the surface). Exit the deep dermis on the opposite wound edge at the same depth. The key is that the needle enters and exits at the level of the deep dermis on both sides, with the bulk of the suture arc in the subcutis. When tied, the knot inverts (buries) into the subcutis. The set-back buried dermal suture is a modification where the entry and exit points are deliberately placed 2–3mm below the wound edge (further from the epidermis). This produces even greater wound edge eversion.

The buried horizontal mattress suture runs parallel to the wound edge rather than perpendicular. It is useful for distributing tension across a wider area in high-tension closures and for securing dermis to periosteum (e.g., scalp to pericranium). Technique: enter and exit the deep dermis on the same side, then cross to the opposite side and repeat. The suture path creates an H-pattern when viewed from the wound surface.

The pulley suture is a high-tension deep closure technique that provides mechanical advantage for approximating wound edges under significant tension. It is essentially a double-loop buried suture. Technique: place a standard buried vertical mattress, but instead of tying, re-enter the tissue on the same side and create a second loop parallel to the first. The double loop distributes force and provides a 2:1 mechanical advantage, similar to a pulley system. Indications: scalp closures with significant tension, back/trunk excisions, any closure where standard buried sutures cannot adequately approximate wound edges.

The simple interrupted suture is the most basic and versatile skin closure technique. Each suture is independent, allowing selective removal and adjustment. Technique: enter the skin 1–3mm from the wound edge (closer on the face, further on the trunk), pass through the dermis with an arc that is wider at the base than at the surface (promotes eversion), and exit at the same distance on the opposite side. Tie with 3–4 throws for nylon. Spacing: place sutures 3–5mm apart on the face, 5–10mm on the trunk. Ensure equal bite width and depth on both sides for symmetric apposition.

The vertical mattress suture is a far-far-near-near technique that provides excellent wound edge eversion. It is the go-to technique when eversion is critical (face) or difficult to achieve (thick skin). Technique: Far pass: enter 4–6mm from the wound edge, pass deep through the dermis, exit 4–6mm on the opposite side. Near pass: reverse direction, enter 1–2mm from the wound edge on the exit side, pass through the superficial dermis, exit 1–2mm on the entry side. Tie. The far pass handles tension and deep apposition; the near pass achieves precise edge eversion.

The horizontal mattress suture runs parallel to the wound edge and distributes tension across a wider area than the simple interrupted suture. It is often used as the first suture placed in a closure to approximate wound edges and reduce tension before completing the closure with simple interrupted or running sutures. Technique: enter 4–5mm from the wound edge, cross to the opposite side and exit at the same distance, then move 5–8mm along the wound and cross back. Tie. Caution: horizontal mattress sutures can strangulate tissue if tied too tightly, causing ischemic necrosis of the wound edges. Use bolsters (small pieces of gauze or tubing under the suture) to distribute pressure.

The running subcuticular (intradermal) suture produces the finest cosmetic result and is the preferred technique for low-tension closures on the face and neck. The suture runs horizontally within the dermis, with no surface marks. Technique: anchor at one end (buried knot or tape), then pass the needle horizontally through the dermis at the same depth on alternating sides of the wound. Each pass should be 3–5mm long, entering and exiting at the dermal-epidermal junction. The suture zigzags through the dermis without penetrating the epidermis. End with a buried knot or exit for pull-through removal. Material: absorbable (Monocryl) for permanent placement, or non-absorbable (Prolene) for removable pull-through technique.

The tip stitch is essential for closing flap tips and V-shaped corners without compromising blood supply to the tip. A standard simple interrupted suture through a narrow flap tip can strangulate its vascular pedicle, leading to tip necrosis. Technique: enter the non-flap skin perpendicular to the surface, then pass horizontally through the dermis of the flap tip (the needle stays intradermal within the tip, never penetrating its surface), then exit through the non-flap skin on the opposite side. This captures the tip without encircling its vascular supply. Indications: all flap tips, M-plasty corners, V-Y closure tips, any triangular wound corner.