Skin GraftSkin Graft

ByByDr. Diyar A. SalihDr. Diyar A. Salih

Plastic Surgery ResidentPlastic Surgery ResidentKurdistan, SlemaniKurdistan, Slemani

Nov 26Nov 26thth, 2007, 2007

Skin functionsSkin functions Protective barrier, against:2. Trauma3. Radiation4. Temperature changes5. Infection

Cont. Thermoregulation, through:2. Vasoconstriction & Vasodilatation3. Insensible fluid loss control

Skin anatomySkin anatomy

Skin varies in thickness depending on: Anatomic location / thickest in the

palm & sole of the feet, thinnest in the eyelids & postauricular region.

Sex / male thicker than female. Age / children have thin skin

Skin layersSkin layers1. Epidermis Stratified

squamous epithelium / Keratinocytes.

No blood vessels /Nutrients from dermis by diffusion through basement membrane.

Cont. Dermis: Papillary dermis

Thinner Loose connective tissue, containing:

1. Capillaries

2. Elastic fibers

3. Reticular fibers

4. Some collagen

Cont. Reticular dermis:

Thicker layer Dense connective tissue, containing:

1. Larger blood vessels2. Closely interlaced elastic fibers3. Coarse, branching collagen fibers arranged in

layers parallel to the surface.4. Fibroblasts5. Mast cells6. Nerve endings7. Lymphatics8. Some epidermal appendages

Epithelial cell sourceEpithelial cell source Epithelial cells re-epithelialize when

the overlying epithelium is removed or destroyed by;

2. Partial thickness burn3. Abrasions4. STSG harvesting.

Cont. Source, intradermal structures

(epithelial appendages):1. Sebaceous glands2. Sweat glands3. Apocrine glands4. Hair follicles

What’s skin graft?What’s skin graft?

Is transplantation of the skin from one part to another part (removed from its blood supply).

TypesTypes

According to the origin: Autograft / from the same

individual Allograft / from different

individual (of the same species)

Xenograft / from different species (gene pig)

Types, cont.Types, cont. According to the dermal thickness:

STSG (epidermis + variable thicknessvariable thickness dermis)

Thin (0.005 – 0.012 inches) Intermediate (0.012 – 0.018) Thick (0.018 – 0.030)

Could be; Meshed Sheet

FTSG (epidermis + entireentire dermis)Contains adnexal structures (sweat glands,

sebaceous glands, hair follicles & capillaries).

THICK GRAFTS ???!!!THICK GRAFTS ???!!!

ADVANTAGES:The thicker the dermal component, the

more the characteristics of normal skin are maintained following grafting, because:

Greater collagen content Larger no. of dermal vascular

plexuses Larger no. of epithelial appendages

THICK GRAFTSTHICK GRAFTS

DISADVANTAGES : More favorable conditions for survival

/ greater amount of tissue requiring revascularization.

CHOICE BETWEEN FULL- AND CHOICE BETWEEN FULL- AND SPLIT-THICKNESS SG.SPLIT-THICKNESS SG.

Depends on the wound’s :2. Condition3. Location4. Size5. Aesthetic concerns

FULL THICKNESS SKIN GRAFTSFULL THICKNESS SKIN GRAFTS

Advantages/

Ideal for the face / where local flap is inaccessible or not indicated.

Retain more characteristics of normal skin, including;

Color Texture Thickness

Less secondary contraction In children grow with the individual Greater sensory return (greater availability

of neurilemaal sheet)

FTSG, Cont.FTSG, Cont.Disadvantages/

More primary contractures More hair follicles transferred More precarious survival (well vascularized bed) Limited range of applications, for;

Small wounds Uncontaminated wounds Well – vascularized wounds

PRIMARY CONTRACTURE: immediate recoil of a freshly harvested graft due to the ELASTIN in the dermis (the more dermis the graft has, the more primary contracture).

FTSG DONOR SITESFTSG DONOR SITES

Closed : Primarily STSG / from another site.

FTSG ProcedureFTSG Procedure

1. Planning ( measuring, pattern made, donor site infiltration “LA +/- Epinephrine”)

2. Harvesting / scalpel3. Donor site closed primarily.4. Graft placed.

STSGSTSG ADVANTAGES:• Less ideal conditions for survival, broader range of

application.• Less hair follicles transferred Used to resurface :

Large wounds Line cavities Mucosal defects Flap donor sites Muscle flap

Donor site heals by epidermal appendages cells immigration & proliferation.

Cont. Disadvantages;

More fragileCan not withstand subsequent radiation therapyMore secondary contractureDo not grow with the individualSmoother & shiner than normal skinAbnormal pigmentation tendency (pale/ white/ hyperpigmented)Donor site more painful than the recipient site

SECONDARY CONTRACTURE: contraction of a healed scar due to MYOFIBROBLAST activity (the thinner the STSG, the greater the secondary contracture).

STSG is more functional than cosmetic

Skin graft survival (Skin graft survival (TAKETAKE))

Depends on the graft’s ability to;• Receive nutrients & vascular

ingrowth from the bed (in 3 phases, 4 theories)

• Close contact & immobilization (skin graft adherence, in 2 phases)

Skin graft revascularizationSkin graft revascularization

Phases;• Serum imbibition;

• Lasts 24 – 48 hr• Fibrin layer forms (adhere the graft to

the bed.• Nutrient absorption into the graft (from

the bed by capillary action).

Skin graft revascularizationSkin graft revascularization

1. Inosculation;• Recipient & donor end capillaries

aligned.

• Kissing capillaries;• Graft revascularized through kissing

capillaries.

Graft revascularization theoriesGraft revascularization theories

• Neovascularization (invade graft)• Communication (between graft & bed

vessels)• Neovascularization + communication• Graft vasculature made up primarily

from its Original vessels before transfer.

How to optimize TAKE?How to optimize TAKE?• Well vascular bed, seldom take in

exposed;• Bone without periosteum (despite orbit or

temporal bone)• Cartilage without perichondrium• Tendon without paratenon

• Close contact (between graft & bed);• Hematomas• SeromasThese 2 immobilize & compromise graft take.

Skin graft adherence phasesSkin graft adherence phases

• First phaseFirst phase: Begins with placement of the graft

on the bed. Graft adhered by fibrin deposition. Lasts 72 hr.• Second phaseSecond phase: Growth of fibrous tissue & vessels

into the graft.

Sheet graftSheet graft Definition/ Is a continuous,

uninterrupted graft. Advantages/

Superior aesthetic result Disadvantages/

Not allowing blood or serum to drain.

Meshed graftMeshed graft Definition/ Is a sheet graft after

multiple mechanical incisions. Advantages/

• Allowing immediate graft expansion.• Cover larger area per cm2

• Allows blood & serum drainage. Disadvantages/

1. Pebbled appearance (aesthetically not acceptable).

What will happen if a wound What will happen if a wound heals without skin graft?heals without skin graft?

Granulating wounds heal secondarily demonstrate the greatest degree of contraction & are most prone to hypertrophic scarring.

EPITHELIAL APPENDAGES IN EPITHELIAL APPENDAGES IN THE SKIN GRAFTTHE SKIN GRAFT

Their no. depends on the dermal thickness.

Graft sweats / depend on:1. Sweat glands no. transferred2. Sympathetic reinnervation of these glands from

the recipient site.

Skin graft reinnervated from: Nerve fiber ingrowth from the recipient site. From the periphry.

Donor site Epidermis/Regenerate from epidermal appendages cells immigration, left

in the dermis. Dermis/Never regenerates. STSG/Original donor site can be used for subsequent harvest

(dependant on donor dermis thickness). Healing/

1. By re-epithelialization from epidermal appendages within nearly 7 days according to its thickness.

2. Enhanced by moist dressing & protection from; Mechanical trauma Desiccation

Donor site selectionDonor site selection

ConsiderConsider/2. Color3. Texture4. Thickness5. Vascularity6. Donor site morbidity

SitesSites/• Any where• Face:

Supracalvicular area Upper eyelid (small amount, very thin)

– Common sites (for STSG): Thigh Buttocks Abdominal wall

SG postoperative careSG postoperative care Graft failure, causes;2. Hematoma3. SerromaRaising the graft, prevent revascularization.• Infection ( > 105 organism per gram of tissue)Minimized by careful bed preparation & early graft inspection

after applying to a contaminated bed.Infection at the graft donor site can converts partial thickness

dermal loss into complete thickness dermal loss.8. MobilizationInterrupt revascularization, prevented by tie-over bolster

dressing on the face & trunk, splinting on the extremities.

Biologic dressingBiologic dressing Definition/Temporary wound coverage, eg. Large burns, necrotizing

facsiitis. Advantage/Protect the recipient bed from desiccation & further trauma until

definitive closure. Biologic skin substitutes/

1. Human allograft (take, rejected after 10 days, unless the recipient immunosuppressed as in large burns, rejection take longer).

2. Amnion3. Xenograft (pig skin), rejected before becoming vascularized

(take). Synthetic skin substitutes/

1. Silicone2. Polymers3. Composed membranes

Human epidermis (in vitro)Human epidermis (in vitro) Human epidermis cultured in vitro to

yield sheet of cultured epithelium that will provide coverage , albeit fragile (due to lack of epidermis), for Large wounds.

THE ENDTHE END

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