Skin and Tissue Grafts
Unlike a flap, which keeps its own blood supply through a pedicle, a skin or tissue graft is a piece of skin or composite tissue that is completely detached from a donor site, cut off from its original blood supply and transferred to a recipient site.
At Haute-Derma, we use skin grafts for large defects that cannot be closed directly, where there is not enough surrounding tissue for a local flap, or where moving a flap could seriously distort key landmarks (such as the eyelids, the rim of the ear or the corners of the mouth). A graft's success depends entirely on its ability to re-establish circulation from the recipient bed through a complex biological process known as "graft take."
The Biology of Graft Take
For a skin graft to survive and fully integrate with the recipient bed, it must pass through three consecutive biological stages during the first 7–10 days:
Stage 1: Plasmatic Imbibition
- The graft soaks up plasma-like fluid from the recipient bed by capillary action.
- The graft's weight increases by 20–30%, and a temporary fibrin layer holds it in place.
Stage 2: Inosculation
- Budding capillaries from the recipient bed link up directly with the graft's existing capillaries (capillary-to-capillary alignment).
Stage 3: Revascularization and Remodeling
- New blood vessels grow deep into the grafted tissue (neovascularization).
- Lymphatic drainage is restored (days 5–7), and nerves begin to regenerate (from the first month).
Prerequisites for Graft Survival:
- A well-vascularized recipient bed: The bed must have a rich blood supply (clean granulation tissue, muscle, or intact periosteum/perichondrium). Grafting onto bare cartilage, bone stripped of periosteum or necrotic tissue is contraindicated.
- Intimate contact: The graft must lie completely flat against the bed, with no blood clot (hematoma) or fluid collection (seroma) in between.
- Complete immobilization: Even very slight shearing forces can tear the tiny vascular bridges forming during inosculation.
Types of Skin and Tissue Grafts in Dermatologic Reconstruction
Split-Thickness Skin Graft (STSG)
The graft contains the entire epidermis and part of the dermis.
- Thin STSG (0.005–0.012 inch / 0.12–0.30 mm): Very high survival rate and fast healing of the donor site, but marked secondary contraction and a less pleasing color match.
- Thick STSG (0.018–0.028 inch / 0.45–0.70 mm): Better cosmetic result and less contraction, but needs a better-nourished recipient bed.
- Indications: Large skin defects after burns, skin loss on the trunk or limbs, and temporary coverage after wide tumor excision.
Full-Thickness Skin Graft (FTSG)
The graft contains the entire epidermis and the entire dermis (with all subcutaneous fat removed).
- Advantages: Excellent resistance to secondary contraction; color, smoothness and texture stay close to the original skin; contains stem cells from hair follicles and sebaceous glands.
- Disadvantages: Requires a very well-vascularized recipient bed; the amount of skin that can be harvested is limited (because the donor site must be closed directly).
- Indications: Reconstruction of facial defects (eyelids, nose, ear rim, cheeks, lips) after excision of BCC/SCC skin cancers.
Composite Grafts
A graft made of two or more tissue types (for example, skin plus cartilage, or skin plus fat).
- Indications: Reconstruction of the alar rim of the nose, the helical rim of the ear or the columella, where a three-dimensional supporting framework is needed.
- Key point: The graft should be kept under 1–1.5 cm, because it relies entirely on nourishment diffusing in from the surrounding wound edges.
FTSG vs. STSG in Detail
| Feature | Full-Thickness Skin Graft (FTSG) | Split-Thickness Skin Graft (STSG) |
|---|---|---|
| Anatomical layers | Epidermis + entire dermis | Epidermis + part of the dermis |
| Graft take rate | Demanding (needs an ideal recipient bed) | Very high (survives even on a poorly vascularized bed) |
| Primary contraction | High (many dermal elastic fibers) | Low |
| Secondary contraction | Very low (preserves the shape of the defect) | Very high (can contract by 30–50%) |
| Cosmetic result | Close match in color and texture | Often patchy in color, shiny and flat |
| Donor site | In front of/behind the ear, above the collarbone, groin crease (requires direct closure) | Thigh, buttock, forearm (no suturing needed; heals on its own) |
| Donor site healing | Primary intention (sutured closed) | Re-epithelializes on its own from the base of the hair follicles |
Tie-Over Bolster Dressing Technique
The most common cause of graft failure is blood or fluid collecting under the graft and separating it from the recipient bed. At Haute-Derma, a tie-over bolster dressing is used routinely to prevent this.
How a Tie-Over Bolster Works:
- The graft is placed in the defect and its edges are sutured with 5-0/6-0 nylon or Prolene, leaving suture tails 3–5 cm long around the edge of the defect.
- Small slits are made in the FTSG (pie-crusting/meshing) so that any blood or fluid can drain out.
- A non-stick petrolatum gauze (Xeroform/Bactigras) is laid directly on the graft surface.
- A sterile cotton or foam bolster cut to the size of the defect is placed on top.
- Opposite suture tails are tied together over the bolster to apply steady, even pressure that holds the graft firmly against the recipient bed.
Managing Complications
Donor Site Selection
The donor site is chosen to match the recipient site in color, thickness, hair direction and texture:
- Eyelid defects: skin from the opposite upper eyelid or from behind the ear (postauricular).
- Nasal and facial defects: skin from in front of the ear (preauricular) or above the collarbone (supraclavicular), which matches facial skin most closely in texture, vascularity and pigmentation.
Causes of Graft Failure and How We Prevent Them
| Cause of Failure | How It Causes Necrosis | Prevention at Haute-Derma |
|---|---|---|
| Hematoma / seroma | Blocks plasmatic imbibition and inosculation | Meticulous bipolar hemostasis; pie-crusting of the graft |
| Shearing force | Tears the new vessels growing into the graft | Precise tie-over bolster dressing; immobilization of the surgical site |
| Infection | Bacteria release enzymes that dissolve fibrin | Careful antiseptic preparation of the recipient bed; systemic/topical antibiotic prophylaxis |
| Inadequate defatting (debulking) | Remaining subcutaneous fat acts as an insulating barrier | All yellow fat completely trimmed from the underside of the FTSG down to the dermis |
Our Standard FTSG Procedure at Haute-Derma
- Recipient bed preparation: After the skin tumor is excised, the recipient bed is cleaned thoroughly. Bleeding points are controlled precisely one by one with fine forceps/bipolar cautery, avoiding broad cauterization that would leave a necrotic surface.
- Patterning and harvesting the graft
- A piece of sterile gauze is pressed onto the defect to make a 1:1 template.
- The template is placed on the donor site (for example, behind the ear) and the incision is drawn 10–15% larger to allow for primary contraction.
- Defatting the underside of the graft (debulking): The FTSG is draped over a fingertip and all yellow fat is trimmed away with fine Metzenbaum scissors until the ivory-white dermis (dermal plexus) is clearly exposed.
- Insetting and pie-crusting
- The graft is placed on the bed and anchored at its four corners, then sutured around its edge with running or interrupted 6-0 nylon, leaving long suture tails.
- The tip of a No. 11 blade is used to make 2–4 small slits in the graft for drainage.
- Tie-over dressing and donor site care
- Petrolatum gauze and a foam bolster are applied and the sutures tied down firmly. The donor site is closed in two layers (deep dermis + epidermis).
- The tie-over dressing is removed after 5–7 days to assess graft survival.
