skin graft , split skin grafting, stg , ssg , split thickness graft , graft , updates on skin graft

1. Skin Review2. Definitions3. Difference between Grafts & Flaps4. Classification of Skin Grafts5. Types of Skin Grafts (according to depth)6. Indications for Grafts7. Donor Sites8. Harvesting Tools

EPIDERMIS DERMIS

EPIDERMIS No blood vessels. Relies on diffusion from underlying

tissues. Stratified squamous epithelium

composed primarily of keratinocytes.

Separated from the dermis by a basement membrane. protective barrier (against

mechanical damage, microbe invasion, & water loss)

high regenerative capacity Producer of skin appendages

(hair, nails, sweat & sebaceous glands)

DERMIS Composed of two “sub-layers”:

superficial papillary & deep reticular.

The dermis contains collagen, capillaries, elastic fibers, fibroblasts, nerve endings, etc. mechanical strength (collagen &

elastin) Barrier to microbe invasion Sensation (point, temp, pressure,

proprioception) Thermoregulation (vasomotor activity

of blood vessels and sweat gland activity)

Immunological surveillance Most skin is thin, hair-bearing, has

sebaceous glands Skin of palms/soles/flexor surface of

digits is thick, not hair-bearing, no sebaceous glands

Vascular supply confined to dermis

GraftA skin graft is a tissue of epidermis and varying amounts of dermis that is detached from its own blood supply and placed in a new area with a new blood supply.

FlapAny tissue used for reconstruction or wound closure that retains all or part of its original blood supply after the tissue has been moved to the recipient location.

GraftDoes not maintainoriginal blood supply.

FlapMaintains original bloodsupply.

1. Autografts – A tissue transferred from one part of the body to another.

2. Homografts/Allograft – tissue transferred from a genetically different individual of the same species.

3. Xenografts – a graft transferred from an individual of one species to an individual of another species.

Classification :

•According to their donor sites & thickness:

Thin intermediate. Thick

Xenograft AllograftAllograft

Grafts are typically described in terms of thickness or depth.

Split Thickness(Partial): Contains 100% of the epidermis and a portion of the dermis. Split thickness grafts are further classified as thin or thick.

Full Thickness: Contains 100% of the epidermis and dermis.

Type of Graft Advantages Disadvantages

Thin Split Thickness

-Best Survival

-Heals Rapidly

-Least resembles original skin.

-Least resistance to trauma.

-Poor Sensation

-Maximal Secondary Contraction

Thick Split Thickness

-More qualities of normal skin.

-Less Contraction

-Looks better

-Fair Sensation

-Lower graft survival

-Slower healing.

Full Thickness

-Most resembles normal skin.

-Minimal Secondary contraction

-Resistant to trauma

-Good Sensation

-Aesthetically pleasing

-Poorest survival.

-Donor site must be closed surgically.

-Donor sites are limited.

4 Phases: Fibrin adhesion Plasmatic imbibition Revascularization: Inosculation & capillary

ingrowth Remodelling: Revascularization & fibrous

attachment in restoring normal histological architecture

Plasmatic Imbibition: Initially graft ischaemic (24 – 48 hrs) Fibrin adhesion Imbibition allows the graft to survive this

period ? Important for nutrition of graft ? Stops drying out

Inosculation & capillary ingrowth: At 48 hrs Through fibrin layer Capillary buds from recipient bed contact graft

vessels Open channels (neo-vascularization) pink graft

Revascularization & fibrous attachment: Connection of graft & host vessels via

anastomoses (inosculation) Formation of new vascular channels by

invasion of graft (neovascularisation) Combination of old & new vessels

(revascularisation) Fibroblast proliferation: conversion of fibrin

adhesion fibrous tissue attachment (anchorage within 4 days)

Appendages:- sweating dependent on no. of transplanted sweat glands & degree of sympathetic reinnervation; will sweat like recipient site in FTSG only- sebaceous gland activity mostly in thicker grafts: SSG usually dry & shiny- hair grows from FTSG if well taken with no complications

Initially white then pinkens with new blood supply

Lymphatic drainage by day 6 Collagen replacement from day 7 to week

6 Vascular remodelling for months

Contraction:- shrinks immediately due to elastic recoil: – FTSG 40%; medium SSG 20%; thin SSG 10%.

- secondary contracture as heals: - FTSG remains same size after above

shrinkage;- SSG will contract as much as possible;- more dermis = less contraction- ? Due to myofibroblasts

Reinnervation: from margins to bed;

Depends on graft thickness and bed;

Uneventful healing leads to near normal 2PD;

Cold sensitivity can be a problem

Based on principle that wounds reepithelialized from the periphery

Expansion provides larger areas from which epithelium can grow

Larger areas can be covered with less skin

Meshing- covers large area- easier to contour- fluid can drain through holes- cosmetic results less than ideal - various mesh ratio

Meshed graft or sheet graft :

AdvantagesLager areaContours irregular surface Drain blood & exudatesIncrease edges_______reepithilialization

DisadvantagesMuch of wound heal 2*______contracture Cobble stone appearance

Sheet GraftJ ointHandsface

Meticulous technique Atraumatic graft handling Well vascularized bed Haemostasis Immobilization No proximal constricting bandages

Systemic Factors Malnutrition Sepsis Medical Conditions (Diabetes) Medications

Steroids Antineoplastic agents Vasonconstrictors (e.g. nicotine)

INDICATIONS OF SKIN GRAFT: 1-Skin loss: - Post –traumatic - Post surgical - pathological process e.g venous ulcer - Extensive burn

2- Mucosal loss: - After excision of leukopakic patch in oral

cavity - vaginal a genesis

Contraindications: 1- Avascular recipient areas : - Cortical bone without periosteum - Cartilage without perichondrim - Tendon without paratenon2- Infection : a- heavily infected wound with copious

discharge(100 000 bact./ gram of tissue). b- Infection by Beta haemolytic

streptococcus

The ideal donor site would provide skin that isidentical to the skin surrounding the recipient

area.Unfortunately, skin varies dramatically from

oneanatomic site to another in terms of:

- Colour- Thickness- Hair - Texture

Post auricular skin Upper eyelid skin Supraclavicular skin Flexural skin Thigh and abdominal skin FTG should be clear of fat FTG sutured edge to edge while STG

overlaps the defect. Use quilting / tie over

Razor Blades Grafting Knives (Blair, Ferris, Smith, Humbly,

Goulian) Manual Drum Dermatomes (Padgett, Reese) **Electric/Air Powered Dermatomes

(Brown, Padgett, Hall)

Electric & Air Powered tools are most commonly used.

Contraction of the graftContraction of the graft