Wound Closure Techniques

Wound closure brings the tissue layers back together at the end of an operation, or after an injury, so the wound can heal by primary intention: clean edges held in apposition until they knit. The choices made here directly affect the scar, the risk of wound breakdown and the risk of infection. Classifying suture materials, naming the techniques and explaining the principles of a good closure are classic basic-science and operative viva material.

The three decisions. How to organise the closure (almost always in layers), what to close it with (suture material, staples, glue or strips) and which technique to use (the specific stitch or device). Under all of them sits the principle the examiner keeps coming back to: well-apposed, slightly everted, tension-free edges, because that is what gives a fine, strong scar and protects the healing wound. The topic builds directly on wound healing; you are closing the wound so those healing phases can proceed undisturbed.

Why it matters in orthopaedics. Closure is the last step of almost every orthopaedic operation, and one of the few parts of the case entirely under the surgeon's control. A poorly closed wound, under tension, with dead space or with inverted edges, can undo an otherwise excellent operation by breaking down or becoming infected, which around a joint replacement or fracture fixation can be catastrophic.

Trauma and elective practice. In trauma, the choice to close primarily, to leave the wound open for delayed closure, or to close a contaminated wound with interrupted sutures is a daily judgement. In elective surgery, the choice between staples, a subcuticular suture or glue affects speed, cost and the scar the patient lives with.

Close in layers. The first decision is structural. Each anatomical layer, fascia, then subcutaneous or deep dermal, then skin, is brought together separately, and that does two jobs.

It takes the tension off the skin. The strong deep layers are closed first and carry the load, so the skin can be apposed under little or no tension. Skin closed under tension heals as a wide, stretched scar and is much more likely to break down.

It obliterates dead space. Closing the layers leaves no pocket under the skin for blood or fluid to collect. A haematoma or seroma in dead space is a culture medium for infection and pushes the wound edges apart.

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How the edges meet. The second set of principles decides whether the edges heal flat and strong.

• Equal, generous bites either side. Take the same depth and width of tissue on each side, dermis to dermis, so the edges come up level, not stepped.
• Eversion. Turn the edges very slightly outward and they settle flat as they heal. Inverted or overlapping edges heal as a depressed, weak scar with epithelium trapped below.
• Approximate, do not strangulate. Tie just tight enough to bring the edges together. Too tight and the suture cuts off the blood supply at the edge and cuts out, causing necrosis, cross-hatch ("railroad") marks and wound problems.
• Atraumatic, aseptic handling. Handle tissue gently, use fine instruments and keep the field sterile; crushed or contaminated edges heal badly.

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Two axes. Every suture sits on two axes, absorbable versus non-absorbable and monofilament versus braided, with its origin, natural or synthetic, as a further property. Examiners expect you to place a named suture on the grid instantly.

Size. Suture size runs on the "0" scale: more zeros means a finer suture, so 5-0 is finer than 2-0. Use the finest suture that will safely hold the load.

Knot security. It depends on the material. A slippery monofilament needs more throws than a braided suture to hold.

Strength goes before the suture does. Examiners probe the fact that an absorbable suture loses its tensile strength well before it is physically absorbed. Strength retention is what holds the wound; absorption is when the foreign material finally clears. Choose a suture whose strength outlasts the time the tissue needs to become self-supporting.

Matching strength to tissue. Read the strength column against the uses. PDS goes into fascia, tendon and other slow-healing layers that need weeks of strength, Vicryl is the deep-layer workhorse for tissues that heal faster, and Monocryl suits a subcuticular skin closure, where the deep layer carries the load and only brief skin-edge support is needed.

The parts of a needle. The needle is half the instrument and a favourite basic-science question. A modern surgical needle has a swage, the crimped end where the suture is attached so the thread trails the needle through a single track (an "atraumatic", eyeless needle), a body held by the needle holder, and a point. Two features decide its use: the point geometry and the curvature.

Curvature. It is described as a fraction of a circle. A 3/8 circle needle suits superficial work on a flat surface, which is most skin closure, while a 1/2 circle turns within a confined space such as a deep cavity. A tapercut needle combines a taper body with a cutting tip for dense or calcified tissue.

The orthopaedic rule of thumb. A reverse-cutting needle for skin, and a taper (or tapercut) needle for fascia and the deeper layers.

The same material can be placed in several ways, each with a job it does best.

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Simple interrupted. Each stitch is placed and tied separately. It is precise, allows fine adjustment of each part of the wound, and is the safest choice in a contaminated or high-tension wound, because if one stitch fails the rest hold. The price is speed, and more individual knots and suture marks. Use it for irregular wounds, areas of high tension, contaminated wounds, and anywhere you need to "dog-ear" correct as you go.

Continuous (running). A single thread runs the length of the wound, tied only at each end. It is fast, distributes tension evenly along the wound and is water-tight, but if the thread breaks or one bite fails more of the wound can open, and there is less precise control at each point. Use it for long, clean, low-tension incisions where speed matters. A continuous barbed line distributes tension along its length instead of at knots.

Mattress sutures. These evert the edges and take tension off the skin. The vertical mattress takes a deep wide bite then a shallow close bite ("far-far, near-near"), which gives strong eversion and good apposition, useful where edges tend to invert. The horizontal mattress places paired bites parallel to the wound; it spreads tension along the edge, helps close gaping or fragile wounds and can also act as a haemostatic stitch. Both cause more tissue strangulation and more prominent marks if left too long or tied too tight.

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Subcuticular (buried intradermal). A continuous suture runs horizontally within the dermis just under the skin, with no stitches crossing the surface. It gives the best cosmetic skin result because there are no cross-hatch marks, and it can be absorbable (no removal) or pulled out if non-absorbable. It is a skin-edge approximator, not a load-bearer, so it relies on a sound deep layer to hold the tension. Use it for clean, well-apposed elective incisions where appearance matters.

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The one technique orthopaedics needs more than any other: Allgöwer-Donati

The problem with a vertical mattress. A conventional vertical mattress crosses the wound twice, once deep and once superficially, so the loop encircles the skin edge on both sides and strangles the subdermal plexus supplying each of them. That is acceptable in a well-perfused wound, and exactly the wrong thing to do to the skin over a tibia, an ankle, a swollen elbow or a fracture blister.

The modification. The Allgöwer-Donati (modified vertical mattress) suture solves it. The needle passes:

1. Far through the full thickness of one side
2. Deep to near across, emerging in the dermis of the opposite side without piercing its epidermis
3. Back through the dermis of that same opposite side
4. Out through the near point on the first side, where the knot is tied

Why it works. Only one skin surface is encircled. The opposite side is held by an intradermal pass alone, so its vertical blood supply is never constricted, and the knot sits on one side, away from the incision. You keep the eversion and the tension-sharing of a vertical mattress and give up half the ischaemic cost.

Where to use it. Wherever the soft-tissue envelope is the thing most likely to fail: the anteromedial tibia, the ankle after a pilon or malleolar fixation, the posterior elbow, and any wound closed over swelling.

The rest of the soft-tissue discipline. Operate when the skin wrinkles rather than when the list allows, handle edges with a skin hook rather than forceps, close the deep layers so the skin carries no tension, and accept a delayed closure rather than force one.

Sutures are not the only way to close skin, and each alternative has a clear niche.

Staples. They are popular for long orthopaedic incisions because they are quick and consistent, and they hold the edges without an inflammatory knot in the wound.

Tissue adhesive. Skin glue polymerises across apposed edges to form a flexible, water-resistant film. It is fast and needs no removal.

Adhesive strips. These are best as a supplement, for example over a subcuticular closure, or for the most superficial low-tension wounds.

Wound factors. High tension favours interrupted or mattress sutures, and contamination favours interrupted sutures and consideration of delayed closure. Location and mobility count too: a wound over a joint needs a stronger, longer-lasting closure. Clean, superficial wounds with well-apposed edges suit glue or strips.

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Patient and practical factors. A cosmetic priority points to a subcuticular or fine interrupted closure. Where returning for removal is a problem, absorbable sutures or glue avoid a second visit. Poor perfusion needs a gentler, longer-retained closure, and for long incisions staples are fast and cheap.

Timing of removal. It balances scar quality against wound strength. Take sutures out earlier where the blood supply is good and cosmesis matters, and later where tension and movement are high.

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• Surgical site infection (SSI) guidance worldwide (for example WHO global SSI guidelines and NICE in the UK) frames closure as part of infection prevention: aseptic technique, gentle tissue handling, obliteration of dead space, and avoidance of tension all protect the healing wound. No major guideline mandates one skin-closure device over another for routine clean wounds.
• Sutures versus staples in orthopaedics is broadly a wash for infection in the best evidence; practice varies by surgeon, unit, and incision type, with staples favoured for speed on long approaches (hip, knee, spine) and subcuticular sutures or glue favoured where cosmesis or no-return-for-removal matters.
• Tissue adhesives and adhesive strips are widely endorsed for clean, low-tension, well-apposed superficial wounds, and as a supplement to a deeper closure - never as the sole closure of a high-tension or contaminated wound.
• Across all settings the principle is constant: closure quality depends far more on sound technique - layered, tension-free, everted, aseptic - than on the particular suture, staple, or glue chosen.