Skin grafting Flashcards
A skin graft is a portion of skin that has been separated from its vascular supply
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Full-thickness grafts (epidermis and dermis plus adnexal structures) are more appropriate where a large area is to be grafted.
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This is true for split thickness grafts.
Split-thickness grafts (epidermis and partial-thickness dermis only) generally give better retention of skin function.
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This is true for FTSG.
Disadvantages of grafts include creation of a second surgical site and suboptimal tissue colour and texture match if an improper donor site is selected.
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Patients typically will eventually experience full sensation at the graft recipient site.
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Rarely, even after prolonged periods.
Split-thickness grafts contain few or no adnexal structures.
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Composite grafts consist of skin and a second type of tissue, most often cartilage.
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A homograft is a graft taken from a donor site on an individual and placed at a recipient site on that same individual.
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This is an autograft.
An autograft is a graft taken from an individual and transplanted to another individual of the same species.
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This is a homograft.
A xenograft (heterograft) is a graft that is transplanted between species (eg. pig to human).
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Re-establishment of a blood supply at the recipient site is essential for graft survival.
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Imbibition is the first stage of graft survival – it is an ischaemic period that lasts for the first 24-48 hours.
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During imbibition, the graft becomes oedematous, but does not increase its weight.
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Weight increases by up to 40%.
During imbibition, fibrin attaches the graft to its bed, the graft is sustained by plasma exudate from the wound bed, and nutrients are obtained by passive diffusion.
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Ultimately the fibrin ‘glue’ is replaced by granulation tissue.
The second stage of graft survival is neovascularisation.
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Inosculation.
The third stage of graft survival is inosculation.
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Neovascularisation
inosculation is second stage
But 2nd and 3rd stages occur concurrently
Inosculation is a process of revascularisation, resulting in the linkage of the graft’s dermal vessels to those present in the recipient bed.
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The process of inosculation begins as early as 48-72hrs and lasts for 7-10 days.
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Occurs concurrently with neovascularisation
Despite the fact that exposed bone and cartilage are poor substances for grafts, delayed grafting at sites initially devoid of periosteum or perichondrium allows for the development of granulation tissue and improved chance of subsequent graft survival
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Neovascularisation refers to capillary ingrowth to the graft from the recipient base and sidewalls.
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Neovascularisation and inosculation typically occur at separate times during healing.
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Often occur in conjunction.
The rate at which a skin graft revascularises is a function of both the fraft thickness and the recipient bed vascularity.
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Under optimal healing condition, full circulation can be restored to a graft after 2 weeks.
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Between the 4th and 7th day.
Re-establishment of lymphatic flow occurs concurrently with restoration of the blood supply and is usually completed by the end of the first week of graft healing.
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Upon return of lymphatic drainage, the graft begins to lose the weight that was acquired during imbibition and likewise begins to lose the bulkiness noted earlier in the healing process.
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Reinnervation of grafts occurs simultaneously with blood revascularisation and return of lymphatic drainage.
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Slow process – begins within 2 months, may not be complete for years (if at all).
Medical issues relevant to skin grafting include coagulation abnormalities, alcohol consumption, smoking, vascular disease, metabolic derangements, and poor nutrition.
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FTSGs generally have greater wound contracture than STSGs.
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The opposite is true.
The metabolic demands limit the overall size of a FTSG to 4-5cm, but STSGs can be used to repair very large defects.
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Sites where STSGs are commonly utilized include the nasal tip and ala, helical convexities and concavities, medial canthus, digits and extremities.
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This is true for FTSGs.
Factors contributing to donor site selection include skin colour, tissue texture, amount of photodamage, and the presence or absence of hair.
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Most common donor sites include preauricular skin, postauricular skin, clavicular and inner upper arm regions, the mesolabial fold and upper eyelids.
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Harvested grafts should be oversized by 40-50% to prevent obtaining a final graft that is too small.
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10-20%.
Defatting of the graft is performed effectively with curved iris scissors.
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Leaving fat on the graft serves as a barrier to nutrient diffusion between the recipient bed and the graft dermis.
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Remoistening the graft periodically with sterile saline or local anaesthetic during the defatting procedure is not recommended.
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Is recommended to prevent desiccation.
