Skin Grafting (STSG & FTSG)
What the Examiner Expects
Transfer of skin from a donor site to a wound that cannot be closed primarily. The examiner expects you to differentiate split-thickness (STSG — includes epidermis and partial dermis, typically 12–18 thousandths of an inch) from full-thickness (FTSG — includes epidermis and entire dermis) skin grafts, know the donor site options (STSG: thigh, buttock; FTSG: groin crease, preauricular, supraclavicular), and understand the requirements for graft survival: a well-vascularized recipient bed (grafts will NOT take on exposed bone without periosteum, tendon without paratenon, or cartilage without perichondrium), immobilization of the graft (bolster dressing), and absence of infection, hematoma, or seroma.
Key Examiner Focus Points
- STSG (split-thickness): epidermis + partial dermis; harvested with dermatome; donor site heals by re-epithelialization
- FTSG (full-thickness): epidermis + entire dermis; donor site closed primarily; better cosmetic result
- Graft survival requires: adequate recipient bed vascularity, immobilization, absence of infection/hematoma
- STSGs contract more than FTSGs; FTSGs are preferred for face, hands, and over joints
- Graft take phases: plasmatic imbibition (24–48 hrs) → inosculation → neovascularization
Common Curveballs
The wound bed has exposed bone without periosteum
A skin graft will NOT take on avascular surfaces. Options: local or free flap coverage to provide a vascularized bed, or create granulation tissue first using negative pressure wound therapy (wound VAC) before grafting. If bone is minimally exposed, burring the outer cortex to expose cancellous bone can allow granulation tissue to form.
Postop day 5, the graft appears dusky with a fluctuant area underneath
Hematoma or seroma under the graft — the most common cause of graft failure. Open the bolster, evacuate the collection, and re-bolster the graft. If the graft is still viable, it may salvage. Meshing STSGs helps prevent fluid accumulation by allowing drainage.
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