Suturing Techniques

When placed correctly, the buried vertical mattress suture traces a heart-shaped path through the tissue. The needle enters at the depth of the wound (base of the dermis or deep reticular dermis), curves upward through the mid-dermis (peak), and then descends back to the wound base on the opposite side. The critical geometric feature is that the widest point of the suture loop (the peak) is at the mid-dermis level, while the narrowest point (the valley) is at the wound base. The knot is buried at the deepest point of the loop. At the bottom of the wound. Which is essential for two reasons: it prevents the knot from extruding through the skin surface, and it places the knot away from the healing wound edge.

First bite: Enter the deep dermis at the wound base on the far side of the wound, approximately 3-5 mm from the wound edge depending on tissue thickness. Drive the needle upward through the reticular dermis, curving to exit at the mid-papillary dermis level approximately 2-4 mm from the wound edge. The needle tip should exit at the level where the dermis transitions from reticular to papillary. Second bite: On the near side, enter at the corresponding mid-papillary dermis level at the same distance from the wound edge, and drive the needle downward through the dermis to exit at the wound base. Tie the knot at the wound base with the knot positioned deep in the wound.

Retract the wound edge at the papillary dermis level. This is the optimal retraction plane because it simultaneously everts the wound edge (exposing the dermal surface for suture placement) and maximizes visualization of the deep wound architecture. Retracting too superficially (epidermis) inverts the edge; retracting too deeply (subcutis) obscures the dermal anatomy.

After placing the first bite of a buried vertical mattress suture (before the second bite), perform the snap test: gently release the wound edge and observe whether it snaps toward the center of the wound. If the edge springs medially, the suture bite has adequate purchase in the dermis and will produce good eversion. If the edge does not move or falls laterally, the bite is too superficial or too deep and should be re-placed.

After completing deep closure, perform the pull test: grasp the wound edges on both sides and pull them apart. Inspect the closure line for any gaps or areas of poor approximation. Each gap indicates a location where an additional deep suture is needed. This simple test prevents the common error of placing too few deep sutures and relying on superficial sutures to carry tension.

In thick-skinned areas, the buried vertical mattress should have a wider bite (farther from wound edge), greater peak-to-valley distance (taller suture loop), and a broad, rounded heart shape. The peak of the suture should still reach the papillary dermis, but the overall loop is larger to encompass the thicker dermal collagen. Take bites 4-6 mm from the wound edge.

In thin-skinned areas, the buried vertical mattress requires a narrower bite (closer to wound edge, 2-3 mm), smaller peak-to-valley distance, and a tall, narrow heart shape. The margin for error is much smaller. Bites that are even slightly too wide or too deep will result in suture extrusion or tissue strangulation. Use 5-0 or 6-0 absorbable suture.

When the suture traces a circular rather than heart-shaped path, the peak does not adequately reach the papillary dermis. This results in poor eversion. The wound edges lie flat or even invert. The fix is to drive the needle more superficially at the peak of the loop, ensuring the peak reaches the mid-to-upper papillary dermis.

When suture bites are too far from the wound edge and too deep, the suture loop encompasses excessive tissue. This creates tissue strangulation, ischemia at the wound edge, and paradoxically poor approximation because the suture cinches tissue too far from the wound margin. The fix is to take bites closer to the wound edge and reduce the depth of the valley.

When the suture initially everts the wound edge but then collapses into inversion as the knot is tightened, the problem is usually that the peak of the suture loop is at different levels on the two sides of the wound. Asymmetric bites cause one edge to evert while the other inverts, and the net result is a flat or inverted closure. The fix is to ensure symmetric bite depths and peak levels on both sides.

The most basic and versatile superficial suture. The needle enters perpendicular to the skin surface 2-3 mm from the wound edge, passes through the dermis in a flask-shaped (wider at base) or symmetric arc, and exits on the opposite side at the same distance from the edge. For proper eversion, the suture should encompass more tissue at depth than at the surface. Knot is tied with the square knot on one side of the wound (not directly over the incision line).

When wound edges are at different heights (a common occurrence after flap advancement or when tissue thickness differs), the simple interrupted suture can correct the discrepancy. The rule is: "bite high on the high side, low on the low side." On the elevated wound edge, enter the needle farther from the wound edge and more superficially. On the depressed edge, enter closer to the edge and deeper. This differential bite geometry draws the higher edge down and the lower edge up, producing a level closure.

Two parallel simple suture bites separated by 4-8 mm. Provides excellent eversion and distributes tension over a wider area. Useful for high-tension areas (scalp, trunk) and as an initial anchoring suture at the center of a long wound. Disadvantage: can strangulate tissue between the two bites if tied too tightly, causing necrosis of the skin bridge.

A continuous suture placed horizontally within the mid-dermis, parallel to the skin surface, with entry and exit points at the wound apices. The suture passes back and forth between wound edges in the horizontal plane, advancing 3-5 mm per bite along the wound length. Provides excellent cosmetic results (no cross-hatch marks) and is ideal for long, straight wounds under minimal tension. Commonly placed with polypropylene (removable) or Monocryl (absorbable). Remove polypropylene running subcuticular sutures at 2-3 weeks.

A specialized suture for securing flap tips without compromising blood supply. The needle enters percutaneously through the non-tip side, then passes horizontally through the dermis of the flap tip (buried component), and exits percutaneously on the other non-tip side. Only the tip passes through the dermis in a buried fashion. No suture passes through the tip epidermis, preserving tip vascularity. This is essential for rotation flaps, advancement flaps, and any closure where a triangular tissue tip must be secured.

For long linear wounds, place the first deep suture at the midpoint, then bisect each remaining segment iteratively. This technique (first suture at 1/2, then 1/4 and 3/4, then 1/8 positions, etc.) ensures symmetric closure and prevents tissue bunching or dog-ear formation at one end.

Instrument ties (using needle driver to create loops) are standard in dermatologic surgery. They conserve suture material and allow precise knot placement. Hand ties are reserved for deep body cavities or when instrument access is limited. For buried sutures, use a surgeon's knot (double first throw) to prevent slippage while the second throw is placed, followed by alternating square throws (typically 4-5 total throws for braided sutures, 5-7 for monofilament).