Skin Grafts

Skin Grafts: Intro & Types - Patch It Up!

• Skin graft: Transfer of epidermis & varying amounts of dermis to a recipient site. Autograft (self), allograft (same species), xenograft (different species).
• Main types: Split-Thickness Skin Graft (STSG) & Full-Thickness Skin Graft (FTSG).

Graft Physiology: Survival Steps - Making It Stick

Graft survival unfolds in three crucial phases: 📌 PIeR.

• Plasmatic Imbibition (Serum Soak): 24-48 hours.
  • Graft passively absorbs plasma-like fluid, nutrients, and oxygen from the recipient bed.
  • Graft swells slightly; cells remain viable but no active circulation.
• Inosculation (Capillary Kiss): Day 3-5.
  • Alignment and direct anastomosis of donor graft capillaries with recipient bed capillaries.
  • Establishes initial, fragile blood flow.
• Revascularization (New Pipes): Day 5-7.
  • New blood vessels actively grow into the graft from the recipient bed.
  • Establishes robust, definitive circulation and lymphatic drainage.

⭐ The 'bridging phenomenon' during inosculation, where recipient and donor capillaries align and connect, is critical for graft survival and typically starts around day 3-4.

Site Management: Donor & Bed - Prime Real Estate

• Donor Site Considerations:
  • Split-Thickness Skin Graft (STSG):
    • Common Sites: Thigh, buttock, scalp.
    • Healing: 7-21 days by re-epithelialization from adnexal structures.
    • Care: Occlusive or semi-occlusive dressings (e.g., paraffin gauze, polyurethane film).
  • Full-Thickness Skin Graft (FTSG):
    • Common Sites: Postauricular, supraclavicular, groin, antecubital fossa.
    • Healing: Donor site typically closed primarily.
    • Pros: Better cosmesis, less secondary contraction.
• Recipient Site Preparation ("Ideal Bed"):
  • Vascularity: Must be well-vascularized (e.g., healthy granulation tissue). Avoid avascular beds (bare bone/tendon without peri/paratenon).
  • Debridement: Thorough removal of necrotic tissue, eschar, and debris.
  • Hemostasis: Meticulous; hematoma or seroma beneath graft is a common cause of failure.
  • Bacterial Load: Infection control critical; bacterial count ideally < 10^5 CFU/gram of tissue.

⭐ A well-vascularized recipient bed with bacterial counts below 10^5 organisms per gram of tissue is essential for successful skin graft take.

Graft Issues: Complications - When Patches Pucker

Common Causes of Graft Failure: 📌 HISSS

• Hematoma: Blood clot under graft, lifts it from bed.
• Infection: Bacterial (e.g., Pseudomonas, Staph), fungal.
• Seroma: Lymphatic fluid collection.
• Shearing forces: Mechanical disruption of adherence.
• Systemic factors/Poor bed: Malnutrition, smoking, diabetes, irradiated tissue, poor vascularity.

⭐ Hematoma formation beneath a graft is the most common cause of early graft failure as it physically separates the graft from its nutrient bed.

Other Complications:

• Contracture: Significant functional/cosmetic issue, esp. over joints.
• Pigmentary changes: Mismatch with surrounding skin (hypo/hyper).
• Hypertrophic scarring/Keloids: Abnormal scar tissue.
• Graft breakdown: Ulceration, chronic instability.

High‑Yield Points - ⚡ Biggest Takeaways

• STSG: Better take, ↑contraction, donor heals spontaneously. FTSG: Better cosmesis, ↓take, donor needs closure.
• Graft survival stages: Imbibition (0-48h), inosculation, then revascularization.
• Hematoma is the commonest cause of graft failure; infection & shear are also key.
• Meshing STSGs increases surface area (e.g., 1:1.5 to 1:6) and allows exudate drainage.
• A vascularized, infection-free bed is vital for graft take.
• Wolfe graft = FTSG; Thiersch graft = STSG.