Suturing and Wound Closure

Sutures are classified by absorbability and material. Absorbable sutures (dissolve in 7–180 days) are used in deep layers where removal is not practical: chromic gut (7–10 days, tensile strength poor, rarely used), PDS (60–90 days, smooth, good for fascia and muscle), Vicryl (60–90 days, braided, good hemostasis), and Monocryl (14–21 days, quick absorption, skin). Non-absorbable sutures (silk, nylon, polypropylene, stainless steel) remain indefinitely and are used in skin where they can be removed, or in areas requiring long-term strength. Silk is smooth and ties easily but can trigger inflammatory reactions; nylon is inert but slippery and prone to loosening; polypropylene is strongest but requires careful knot technique. Needle types: cutting needles (sharp, used in skin and tough tissue) vs. non-cutting (tapered, used in soft tissue and vasculature to avoid tearing). Size ranges from 11-0 (finest, facial work) to 0 (larger, abdominal closure). Match the suture to the tissue and intent: deep fascia needs strong PDS or Vicryl; muscle needs absorbable suture; subcutaneous needs fine absorbable; skin needs non-absorbable (to be removed) or skin adhesive for low-tension wounds.

Knot security depends on technique and material. The most common surgical knot is the square knot (reef knot): right-over-left, left-over-right, pulled tight on each throw. Two throws minimum, but most surgeons use three for critical areas (fascia). Technique: (1) hold the suture ends with your fingers or forceps, wrap one end around your hand and the needle driver once, then pass the other end through the loop and pull tight (first throw); (2) reverse the direction (left-over-right if first was right-over-left) and repeat (second throw). (3) Maintain tension throughout to avoid slipping. (4) Trim the ends short with scissors, leaving 1–2mm for skin sutures (cut closer for internal sutures). Surgeons vary in preference: some favor instrument ties (using needle driver and forceps together), others hand-tie. Practice on models until knot-tying is automatic; a loose knot risks dehiscence (wound opening). Slippage is the main failure mode, especially with slippery materials like polypropylene; use at least three throws for polypropylene fascia closure.

Primary closure: closure of a fresh surgical wound or acute laceration within 6–12 hours before bacteria proliferate; the wound edges are clean, vascular, and free of contamination. Healing proceeds through normal inflammation, proliferation, and remodeling — fastest and best cosmetic outcome. Secondary closure (healing by intention): closure of a wound that has been left open (infected wound, chronic ulcer) for days or weeks, allowing granulation tissue to form; then the wound edges are brought together. Healing is slower and scarring is more prominent. Tertiary closure or delayed primary closure: closure of a contaminated wound after a period of open observation (24–48 hours) to ensure no infection before closing. The wound is left open, the patient is observed for signs of infection, then sutures are placed to bring the edges together. Primary closure is always preferred when the wound is clean and time permits because it heals fastest and leaves the least scar.

Tension control is an art. Too much tension strangulates tissue (ischemia, necrosis, increased scarring); too little tension gaps the edges (blood collections, hematoma, dehiscence). Proper technique: (1) use your non-dominant hand (holding forceps on one edge of the wound) to gently evert the edge (flip it slightly outward so the raw surface faces out); (2) insert the needle perpendicular to the edge, at a distance from the edge equal to the thickness of the tissue (e.g., 3–4mm for skin, deeper for fascia); (3) cross the wound at a slight angle (not straight across) so the needle emerges at the same depth on the opposite side; (4) pull the knot with steady, even tension — not yanked tight, but snug. Spacing: place stitches roughly 5–7mm apart in skin (closer for the face for better cosmesis, wider for scalp). If you are placing a stitch and the edges gape widely, do not force them together; instead, you may need to place additional deep sutures to close the dead space first, or reconsider the closure plan. A well-closed wound should have edges that are slightly everted (not sunken) and lying flat without tension.

Epidermal (simple interrupted) sutures close only the skin layer; they are visible, require removal (usually 7–10 days), and are best for quick, low-risk wounds. Dermal (intradermal) sutures anchor in the dermis, do not cross the epidermal layer, and do not require removal if absorbable (dissolve in 7–10 days). Intradermal sutures are faster, less visible, and ideal for cosmetically sensitive areas (face, neck, décolletage) or if the patient is unreliable about follow-up. Combination approach: place an intradermal suture to bring the dermis edges together and evert slightly, then close skin with a running epidermal stitch or skin adhesive. Subcuticular sutures (running sutures in the dermis just below the epidermal layer) are often used in plastic surgery for an almost invisible scar. Choice depends on the wound depth, cosmetic importance, and removal feasibility.

Complex closures are performed in layers to restore anatomy and ensure strength. Typical abdominal closure: (1) close the peritoneum (innermost layer) with continuous absorbable suture (PDS or Vicryl), running along the peritoneal edge; (2) close the rectus fascia (the strong sheath around the abdominal muscles) with interrupted absorbable sutures or running suture, ensuring no gaps (a fascial dehiscence is a serious complication); (3) close subcutaneous tissue (if >5mm deep) with absorbable sutures to obliterate dead space and reduce seroma (fluid collection); (4) close skin with non-absorbable sutures or skin adhesive. Each layer must be secure: interrupted sutures in fascia are more secure than running sutures because a break in the line does not undo the whole layer. Pull each knot snugly but not strangulating. The logic: peritoneum is not strong, so it is closed for hemostasis and anatomy; fascia is the strength layer and must be absolutely secure; subcutaneous sutures reduce complications; skin is for alignment and cosmesis. Surgeons learn this layering through hundreds of cases under supervision.

Dehiscence (wound opening) is the failure of a surgical wound to heal by primary intention, usually due to inadequate closure strength, tension, or infection. Risk factors: (1) inadequate knot security (loose suture, slippage); (2) insufficient sutures or wide spacing; (3) too much tension pulling on the edges; (4) infection (bacteria weaken tissue); (5) poor nutrition (lack of vitamin C, protein, or zinc impairs healing); (6) coughing or straining (patient pops stitches); (7) obesity or abdominal distension (increased tension on fascia); (8) chronic disease (diabetes, immunosuppression). Prevention: (1) ensure proper knot technique with multiple throws in strong material; (2) place sutures close enough (5–7mm skin, 5–10mm fascia) with no gaps; (3) use proper tension (snug but not strangulating); (4) if the wound is under tension, consider using a tension-relief technique (retention sutures, mesh reinforcement); (5) optimize nutrition and glucose control pre- and post-op; (6) educate the patient on avoiding heavy lifting, straining, or coughing; (7) if dehiscence occurs, do not force closure; instead, evaluate for infection (culture the wound), allow it to drain, and consider delayed or secondary closure once the infection clears.

Most surgical trainees need 300–500 supervised suturing experiences (knots tied under observation, feedback received) to reach competency. Start with knot-tying on models (suture pad, foam block, or gauze) for 20–40 hours until you can tie a square knot in 15 seconds with one hand and maintain tension. Progress to simple lacerations (often done by residents in the emergency department) with supervision: start with clean, straight wounds on the arm or leg. Graduate to facial lacerations (higher cosmetic demand, smaller needle, finer suture). Then move to surgical wounds: skin, subcutaneous, muscle, fascia in the operating room under attending surgeon supervision. Surgical residency requires 500+ hours of operative time in the first year alone, with suturing and closure comprising a large portion. Plastic surgeons and reconstructive specialists invest an additional 1–2 years learning advanced closure techniques (flaps, grafts, layered reconstruction). The practical point: you cannot learn suturing from reading; you must do it repeatedly with feedback until the motor pattern is automatic.