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Skin Transplantation

Pre-operative considerations

Authors: Christian Kaare Paaskesen Med. Stud, Eirini Tsigka, MD, MSc and Magnus Avnstorp, MD.

Skin grafts are generally used when other options are not accessible or suitable. I.e healing by secondary intention, primary closure, a local flap or even a free microsurgical flap .

Optimal donor site

To achieve the best cosmetic result, the donor site must match the recipient site in terms of color, texture, thickness and consistency.

All skin grafts contract immediately after harvest, and again after revascularization of the recipient bed, this is known as primary contracture and secondary contracture (1). 

The most common types of skin grafts are split-thickness skin grafts and full-thickness skin grafts (Table 1).

Comparing split-skin and full-thickness skin grafts

Split-thickness skin graftFull-thickness skin graft
Consist of epidermis and partial dermisConsist of epidermis and entire dermis
Exhibit less primary contraction (due to elastin fibers)Exhibit more primary contraction
Exhibit more secondary contraction (due to myofibroblast process)Less secondary contraction, that’s why full thickness is preferred to joint surfaces.
Less stretch and mobility, vulnerable to shear forces though.Less fragile to subsequent trauma (due to larger amount of dermis)
Donor site heals by secondary intention (can be used for larger wound areas)Donor site needs primary closure (surface of donor is limited)
Possibility for expanding by meshing 1:1,5, 1:2 or 1:3.Meshing gives limited expansion, especially in facial areas.
Less metabolic demands (higher chance for survival and healing)Higher metabolic demands, nutrients and revascularization
Less skin structures (hair follicles, sweat glands)More skin structures
Present final contraction approximately 10-20 % of the primary sizeUp 40 % final contraction
Table 1. Comparing a split- and full-thickness grafts
Split-thickness skin graft. Green line indicate what layers are included.
Full-thickness skin graft. Green line indicate what layers are included.

The Recipient bed

Skin grafts depend on the ingrowth of capillaries from the recipient site for their ultimate survival. The recipient bed should therefore be as well vascularized as possible.

The surgeon must be aware of recipient beds with poor vascularization, such as:

  • Exposed cortical bone
  • Cartilage without perichondrium
  • Nerves
  • Fascia
  • Tendons

If the skin graft needs to be placed on bone, cortical bone must be removed to reach spongious bone, which is a more well vascularized wound bed (2).

Causes of Graft Failure

  • Obstacles for revascularization between skin graft and recipient site (hematoma, seroma, shear forces)
  • Infection
  • Other medical comorbidities (Diabetes mellitus, peripheral arterial disease, venous insufficiency, edemas, history of radiation)
  • Nutritional deficiencies
  • Nicotine use
  • Hypoxemia

Pitfalls

  • Placing graft on a dirty, bleeding or avascular recipient bed e.g. cortical bone etc
  • Placing split-thickness skin grafts near free margins like eyelids, nasal alae and oral commissure
  • Skin grafts contract immediately after harvest, and again after revascularization

Pearls

  • Maintain correct epidermal and dermal orientation when working with split-thickness skin grafts
  • Matching the donor and recipient site in terms of color, texture, thickness and consistency

References

  1. Thorne, Charles Hm et al, Grabb and Smith’s Plastic Surgery (Wolters Kluwer, 7th ed, 2013;2014;)
  2. Shimizu R, Kishi K. Skin graft. Plast Surg Int. 2012;2012:563493. doi:10.1155/2012/563493

Acknowledgments

IllustrationsChristian Kaare Paaskesen Med. Stud.

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