Skin

Skin

Presented by : Dr Mohammed Haneef

Moderator : Dr NEELAKAMAL. H. HALLUR

Contents Introduction Anatomy of skin Skin grafts-types Skin grafts knives Graft take Fate of skin graft Skin substitutes Skin Flaps Conclusion

Skin is a remarkable organ of the body which is able to perform various vital functions. It can mould to different shapes, stretch and harden, but can also feel a delicate touch, pain, pressure, hot and cold, and is an effective communicator between the outside environment and the brain

Introduction It is complex organ system of the body. It double layered sheath , cushioned by the underlying

subcutaneous fat, which covers entire surface of body. It is not uniformly thick. The average thickness of the skin is about 1 to 2mm. In the sole of the foot, palm of the hand & in the interscapular

region –thick(5mm) Thin over the eyelids.

Skin makes up to 12-15% of an adult's body weight. Each square centimeter has 6 million cells, 5,000 sensory points, 100 sweat glands and 15 sebaceous glands. It consists of 3 layers: the epidermis (the outer layer), the dermis ('true skin') and the subcutaneous (fat) layer

Functions of skin There are 6 skin functions: Sensation - the nerve endings in the skin identify touch, heat, cold, pain and light

pressure. Heat regulation - the skin helps regulate the body temperature by sweating to cool

the body down when it overheats and shivering creating 'goose bumps' when it is cold. Shivering closes the pores. The tiny hair that stands on end traps warm air and thus helps keep the body warm.

Absorption - absorption of ultraviolet rays from the sun helps to form vitamin D in the body, which is vital for bone formation. Some creams, essential oils and medicines (e.g. HRT, anti-smoking patches) can also be absorbed through the skin into the blood stream.

Protection - the skin protects the body from ultraviolet light - too much of it is harmful to the body - by producing a pigment called melanin. It also protects us from the invasion of bacteria and germs by forming an acid mantle (formed by the skin sebum and sweat). This barrier also prevents moisture loss.

Excretion - Waste products and toxins are eliminated from the body through the sweat glands. It is a very important function which helps to keep the body 'clean' from the inside.

Secretion - sebum and sweat are secreted onto the skin surface. The sebum keeps the skin lubricated and soft, and the sweat combines with the sebum to form an acid mantle which creates the right ρH balance for the skin to fight off infection.

Structure of skin

Skin is made up of three layers namely;

1.Epidermis

2.Dermis (which consists of connective tissue)

3. Hypodermis

The two are separated

by a lamina, the

basement membrane.

Epidermis Dermis

It consists of two main elements : the epithelial cells & the pigment system

The epidermis of the skin is formed by stratified squamous epithelium, the epithelial cells are arranged in 5 layers,

1. Stratum corneum,

2. Stratum lucidum,

3. Stratum granulosum,

4. Stratum spinosum &

5. Stratum germinativum

The dermis is the layer responsible for the skin's structural

integrity, elasticity and resilienceThe dermis consists of two layers:

Superficial or papillary layer Contains widely separated, delicate, collagenous elastic

and reticular fibers run vertical to the surface, in meshed with capillaries and surrounded by ground substance.

Deeper reticular layer contains sebaceous glands, sweat glands, hair follicles and a small mumber of nerve and muscle cells. Sebaceous glands, based around hair follicles, produce sebum, an oily protective substance that lubricates the skin and hair and provides protection by forming an acid mantle when mixed with sweat

Subcutaneous tissue is the deepest layer of the skin located under the dermis and consisting mainly of fat cells. It acts as a shock absorber and heat insulator, protecting underlying tissues from cold and trauma. The loss of subcutaneous tissue in later years, leads to facial sag and makes wrinkles more visible. To counteract it, a cosmetic procedure where fat is taken from elsewhere in the body and injected into facial areas, is common these days.

Stratum corneumMost superficial layerConsists of dead cells – CorneocytesThe epithelial cells lose their nucleus.The cytoplasm is flattened with fibrous protein

known as keratin.

Stratum lucidumA clear band, separate this layer from the outer

layer of epidermis.Made up of flattened epithelial cells.Cells have degenerated nucleus.

Stratum granulosum

More superficially, the cytoplasm of the cells contains granules, the area is known as the stratum granulosum.

Stratum spinosumIn the stratum spinosum / prickle cell layer, which

is superficial to the basal layer, the cells are larger and are joined by tiny fibrils known as tonofibrils

Stratum Germinativum:Deepest layer with irregular, tall, columnar cells.Attached by hemidesmosomes to basal lamina.Doesn’t stain with H& E.Proliferates & synthesizes intermediate filaments/

tonofilaments.As these cells pass through next layer,

tonofilaments form bundles called tonofibrils.

Dermis

The dermis consists of two layers :

Superficial or papillary layerContains widely

separated, delicate, collagenous elastic and reticular fibers run vertical to the surface, in meshed with capillaries and surrounded by ground substance.

A deep / reticular layerDense, coarser, branching, collagenous fibers

arranged in layers mostly parallel to the surface.Connective tissue cellsFibroblast

DERMOEPIDERMAL JUNCTION :

An irregular wavy line ; the ridges / rete pegs projects into the dermis, enclosing between them the vascularised dermal papillae.

The cells of the basal layer of the epidermis are attached to the basement membrane, a connective tissue layer, by hemi-desmosomes.

The AdnexaDownward prolongations

of the epithelium, in the form of eccrine sweat glands & pilosebaceous units which in certain sites include apocrine glands, penetrate into the dermis.

These specialised structures are collectively called the Adnexa.

HAIR FOLLICLES :

Cells of developing epidermis invade the dermis during embryonic development to form intradermal epithelial structures; the hair follicles, sebaceous glands, and sweat glands.

Hair follicle extends into the dermis to a varying depth, towards its deepest part it expands to form hair bulb.

Sebaceous glandMost sebaceous glands are

appendages of hair follicles and open inside the pilosebaceous canal.

They are generally found on the underside of the hair follicles.

The lobules of sebaceous glands are solid masses of cells that gradually become filled with fat granules and finally disintegrate, giving forth an oily secretion known as sebum.

FUNCTIONS :This provides lubrication for the hair, keeps skin

supple, protects it against friction, and makes it more impervious to moisture.

SWEAT (ECCRINE AND APOCRINE) GLANDS:

Eccrine sweat glands are found over the general body surface.

STRUCTURE :These are simple, tubular glands, usually coiled at

the base of the dermis.

The ducts of the sweat glands pass through the epidermis and open either at sweat pores on the skin surface or above the opening of sebaceous glands in the hair follicles walls.

Pigment systemMelanocytes: the cells

responsible for production of pigment in the epidermis.

Lie among the cells of the basal layer

CLINICAL IMPLICATION :Transplanted skin temporary severed from the nerve

connections, lacks the lubrications normally supplied by the eccrine and apocrine glands and is therefore dry and more susceptible to injury.

Bland creams, such as lanolin / cocca butter, should be applied to grafted skin until reinnervation and function of the secreting glands are restored.

Place incisions along the borders of aesthetic units rather than across them.

When excising lesions from the face, the best results often are obtained by excising a complete aesthetic unit and replacing it with a skin graft, even if this increases the amount of skin removed when compared to what is required to achieve an adequate margin around the lesion.

Postauricular area is preferred in men. For FTSG In contrast preauricular skin in females is preferred source

as it is hairless & has more solar aging. For FTSG

skin varies in thickness based on its anatomic location and the sex and age of an individual.

Skin is thickest on the trunk, palms and soles of the feet, while the thinnest skin is found on the eyelids and in the postauricular region.

Male skin is characteristically thicker than female skin in all anatomic locations.

Children have relatively thin skin.

This thinning is primarily a dermal change, with loss of elastic fibers, epithelial appendages and ground substance.

Dermis thickens up to 4th or 5th decade.

Applied aspect

Skin grafts –

Definition

Skin transplanted by completely detaching a portion of integument from its donor site and transferring it to a host bed, where it acquires a new blood supply to ensure the viability of the transplanted cells.

0rGraft

A 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.

Skin flaps – Defined as a portion of skin and subcutaneous tissue which is raised from the donor site – the flap is left attached to the surrounding skin by a vascular pedicle.

Classification

Skin grafts Skin flaps

Classification:

By species:

a. Autograft

b. Allograft

c. Xenograft

By thickness:

d. Full thickness

e. Split thickness

By application:

f. Temporary

g. Permenant

h. Pinch graft

Classification:

Blood supply

a. Random

b. Axial

Tissue movement

c. Rotation

d. Advancement

e. Transposition

Skin graftsFree skin grafts are pieces of skin that have been

served from their local blood supply and transferred to another location.

Free skin grafts are divided into 4 categories

FTSGsComposed of

epidermis and entire thickness of dermis

STSGs

Composite graft

Free cartilage graft Composed of full

thickness epidermis and partial thickness dermis

2-different tissue types composed of skin and cartilage

Consists of cartilage with its overlying perichondrium

Thin (0.005-0.012 inch)

Medium(0.012-0.018 inch).

Thick(0.018-0.030 inch)

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.

Indications

Full thickness graft Split thickness graft

If adjacent tissue has premalignant or malignant lesions and precludes the use of a flap.

Specific locations that lend themselves well to FTSGs include the nasal tip, helical rim, forehead, eyelids, medial canthus, concha, and digits.

Used when cosmetic appearance is not a primary issue or when the size of the wound is too large to use a full thickness graft.

Chronic Ulcers

Temporary coverage

Correction of pigmentation disorders

Burns

CUTTING : FULL-THICKNESS GRAFT vs SPLIT THICKNESS GRAFT

INSTRUMENT : Cut free-hand with a

scalpel; no dermatome is used.

TEMPLATE : Usually a pattern of

the defect to be grafted is made and transferred to the donor site where it is outlined.

INSTRUMENT: A variety of dermatomes are

available for cutting split-thickness grafts.

Air/electric powered dermatomes The free hand knife are used to cut

lengthwise on the extremity; Drum dermatomes are used sidewise

across the extremity.

Humby knife as modified by Blair and Watson

Other skin graft knives are The Blair-Brown knife The watson knife The cobbett knife Silver’s Miniature Knife.

WOUND PREPARATION The most critical component of successful skin grafting is

proper wound preparation. Failure to establish optimal physiologic conditions to

accept and nourish the graft is the source of most graft failures.

Skin grafts will not survive on tissue with a limited blood supply, such as bone, cartilage, tendon, or nerve.

Skin grafts will survive on Periosteum, Perichondrium, Perineurium, Dermis, Fascia, Muscle and Granulation tissue.

Wounds secondary to radiation also are unlikely to support

a graft. Chronic wounds must be free of pus and should have

– healthy, pink to beefy red appearance with an ideal wound pH – 7.4

Epithelial migration at the edges of the granulation surface may sign that wound is ready for skin graft.

The wound also must be free of necrotic tissue and relatively uncontaminated by bacteria.

Bacterial counts greater than 100,000 per square centimeter are associated with a high likelihood of graft failure.

To achieve an adequate wound bed Debridement, Dressing changes, and Topical or systemic antibiotics - prior

to grafting.

OPERATIVE TECHNIQUES Careful operative technique is necessary to maximize graft

survival. After initiation of appropriate anesthesia, the wound first is

prepared for grafting. This includes Cleansing of the wound with saline or diluted

Betadine, Judicious debridement and Meticulous hemostasis. Hemostasis may be achieved through Ligation Gentle pressure Application of a topical vasoconstrictor or Electrocautery.

FULL-THICKNESS SKIN

GRAFTS These grafts do not contract

and do not change in colour or skin texture.

Require well-vascularized, uncontaminated recipient site for survival.

Lifespan of FTSGS when wrapped in gauze , moistened in saline & stored in fridge at 4 degree Celsius is 3 weeks.

FULL-THICKNESS SKIN GRAFTS The wound pattern - outlined over the donor region - enlarged by 3-5% to compensate for primary contracture, which will occur due to the elastic fiber content of the graft dermis. The donor site - infiltrated with local anesthetic with or without epinephrine. After incising the pattern, the skin - elevated with a skin hook, keeping a finger of the nonoperating hand on the epidermal side of the graft. This provides tension and a sense of graft thickness while the operating hand dissects the graft off of the underlying subcutaneous fat. Any residual adipose tissue - trimmed from the underside of the graft because this fat is poorly vascularized and will prevent direct contact between the graft dermis and the wound bed.

Trimming of residual fat is best accomplished with sharp curved scissors with the graft stretched over the nonoperating hand until only the white glistening dermis remains.

Grafts may be pie-crusted to allow egress of wound fluid from beneath the graft.

These openings will not prevent graft loss from an underlying hematoma.

This technique - performed by making multiple stab wounds through the graft with a number 15 scalpel blade.

Once the graft is harvested reinspect the recipient site for hemostasis.

Place the graft with the dermal side down over the wound bed.

Also take care to prevent wrinkling or excessive stretching of the graft.

The graft then must be secured in place to provide stability during initial adherence and healing.

Absorbable sutures are preferable because they do not require removal.

Usually, 4 corner sutures are placed to hold the graft in the proper orientation.

Then a running suture is placed around the periphery.

Perfect epidermal-to-epidermal approximation ensures optimal cosmetic results.

A dressing is chosen - provide uniform pressure over the entire grafted area through a nonadherent, semi-occlusive, absorbent dressing material.

Immobilize the graft, Prevent shearing and Prevent hematoma formation beneath the graft. Another dressing choice for an irregularly contoured

wound or wound with high levels of exudate - vacuum-assisted closure (VAC) sponge.

It conforms to the wound surface by suction and promotes skin graft adherence on removing exudate and edema from surrounding tissues.

Finally, the graft may be treated open by placing no dressing except a layer of ointment to prevent desiccation.

This technique - susceptible to hematoma or seroma formation beneath the graft because no pressure is applied.

This technique is used only occasionally in facial grafting. Graft adherence - maximal in the first 8 hours postgrafting

but the initial dressing left in place for 3-7 days unless pain, odor, discharge occur.

GRAFT SURVIVAL An initial adherence to the wound bed via a thin fibrin

network temporarily anchors the graft until definitive circulation and connective tissue connections are established.

Begins immediately and probably is maximized by 8 hours postgrafting.

The period of time between grafting and revascularization of the graft - the phase of plasmatic imbibition.

The graft imbibes wound exudate by capillary action through the spongelike structure of the graft dermis and through the dermal blood vessels.

This process is entirely responsible for graft survival for 2-3 days until circulation is reestablished.

During this time, the graft typically becomes edematous and increases in weight by 30-50%.

Revascularization of the graft begins at 2-3 days. Inosculation is the establishment of direct anastomoses

between graft and recipient blood vessels. Full circulation to the graft is restored by 6 or 7 days. Without Initial adherence, Plasmatic imbibition, and Scularization, the graft will not survive. Wound contraction may present serious functional and

cosmetic concerns - depending on location and severity.

On the face, it may produce Ectropion, Retraction of the nasal ala or Distortion of the vermilion border.

Contraction - begins shortly following initial wounding, progressing slowly over 6-18 months following grafting.

Myofibroblast is believed to be responsible for this contraction.

Deep dermal component is able to suppress myofibroblast function.

Hair - more likely to grow from full-thickness grafts than from split-thickness grafts.

Sweat glands and sebaceous glands initially degenerate following grafting.

Sweat gland regeneration - dependent on reinnervation of the skin graft with recipient bed sympathetic nerve fibers.

Sebaceous gland regeneration - independent of graft reinnervation and retains the characteristics of the donor site.

skin graft - lacking normal lubrication of sebum produced by these glands.

Grafts may appear dry and undergo scaling during this period.

Full-thickness grafts - soft and pliable with time as sebaceous gland regeneration occurs.

Reinnervation of the graft occurs from the recipient bed and from the periphery along the empty neurolemma sheaths of the graft.

Full-thickness grafts reinnervate more completely than do split-thickness grafts.

Pain usually is the first perceived sensation, followed later by touch, heat, and cold.

Pigmentation returns gradually to full-thickness skin grafts. Graft be protected from direct sunlight for at least 6 months

postgrafting or even longer. Hyperpigmentation - treated with dermabrasion and laser

resurfacing.

GRAFT FAILURE The most common reason for skin graft failure is Hematoma beneath the graft. Seroma formation may prevent graft adherence to the

underlying wound bed - preventing the graft from receiving the necessary nourishment.

Movement of the graft or shear forces - lead to graft failure through disruption of the fragile attachment of the graft to the wound bed.

Poor recipient site. Technical error also may yield graft failure. Graft upside down will result in complete graft

loss Applying excess pressure, Stretching the graft too tightly, or Handling of the graft in other traumatic ways

MUCOSAL GRAFTS :Full thickness mucosal grafts to reconstruct nasal

and conjunctival defects can be harvested from the inner aspect of the cheek.

Care must be taken to avoid injury to the parotid

duct.

Other mucosal graftsNasal mucous membrane To support a lower eyelid, a composite graft of

nasal mucous membrane with accompanying septal cartilage may be removed.

Conjuctival tissue

ADVANTAGESColor and texture of grafted skin are optimally

maintained.More normal sweating and sebaceous activity

maintained.Less contour irregularities.Contraction at recipient site is limited.Hair is transferred with graft .Graft in children will grow as the child grows.

SPLIT-THICKNESS SKIN GRAFT Categorized further as Thin (0.005-0.012 in), Intermediate (0.012-0.018 in), Thick (0.018-0.030 in), based on the thickness of the harvested graft. Require less ideal conditions for survival and have a much

broader range of application. Used to Resurface - large wounds, - mucosal deficits - muscle flaps Line cavities and Close flap donor sites

Donor sites heal spontaneously because of the remaining epidermal appendages - reharvested once healing is complete.

They contract more during healing and do not grow with the individual.

They tend to be abnormally pigmented or hyperpigmented particularly in darker-skinned individuals.

Thinness, Abnormal pigmentation, and Frequent lack of smooth texture and hair growth make split-thickness grafts more functional than cosmetic. Common sites include the Upper anterior Lateral thighs. Upper inner arm is a cosmetically superior donor site.

HARVESTING Most commonly used technique involves use of a

Dermatome, which provides rapid harvest of large uniform-thickness grafts. Dermatomes may be

Air-powered, Electric, used to cut lengthwise. Free hand knife Drum dermatomes – used sidewise across

the extremity. They require anesthesia – painful. LA with adrenaline is preferred to reduce blood loss.

Rapidly oscillating side-to-side blade advanced over the skin with thickness and width - surgeon preference.

Freehand With A Knife: (eg, Humby knife, Weck blade, Blair knife).

Disadvantages - grafts with irregular edges and varying thicknesses.

Air- or electric-powered dermatomes; Most commonly used devices today. The blade has a correct and an incorrect orientation

and inexperienced personnel may easily confuse the two.

Insertion of a No 15 blade scalpel simulates a thickness of 0.015 inches and used to check depth settings are uniform and correct.

It is useful to lubricate the skin and dermatome with mineral oil - easy gliding of the dermatome over

skin.

Dermatome is held at a 30- to 45-degree angle from the donor skin surface.

Dermatome is activated and advanced in a smooth continuous motion over the skin with gentle

downward pressure. Dermatome is tilted away from the skin and lifted off

of the skin to cut the distal edge of the graft and complete the harvesting.

The graft may then be gently washed of lubricant and used for grafting with or without meshing.

Exposure of fat indicates graft was performed too deeply.

Thicker the graft – more opaque it is. Ideal skin graft is slightly translucent.

Graft thickness – judged by type of bleeding – on donor site area. Superficial graft – small bleeding points. Deeper cutting – fewer bleeding points which bleed more. Too deep graft – exposure of fat. Used – Shaving scars where there is hypertrophy without

contracture. - Tangential excision of burns.

CASTROVIEJO, REESE, PADGETT-HOOD, BROWN, DAVOL-SIMON, ZIMMER

COMMONLY USED DERMATOMES

CASTROVIEJO DERMATOME

Small electric dermatome – for harvesting mucous membrane grafts for reconstruction of

Eyelid deformities. Socket Motor moves – small cutting head with blade that

controls thickness of the cut. Another small electric dermatome – Davol company

with disposable head. Cutting blade on the small power dermatomes tend to

lose their sharpness rapidly.

REESE DERMATOME It is a modification of the Padgett-Hood dermatome. Accompanying set of shims – permits careful

calibration of thickness. Disadvantage – if the graft is too thick or thin, it is

difficult to change the calibration in the middle of a skin graft removal.

Once the procedure is over – remove the disposable blade to avoid injury to the operator.

Graft is removed by gentle rubbing with a sponge gauze soaked in normal saline solution.

When it become necessary to use a donor site such as neck, chest or flank – inject normal saline until it becomes level with the surrounding area.

PADGETT DERMATOME

It is lighter and can be used more rapidly. There is now available a plastic tape with glue on both

surfaces. Outer protective cover is removed from the tape and

latter is applied to the drum of the dermatome. Thickness is to 0.004 inch to compensate for

thickness of the tape.

SELECTION OF DRUM DERMATOME Reese dermatome provide – 7*4 inch graft cutting size. Padgett dermatome – 8 inch long and comes in three

widths. Small – 3 inch wide. Medium – 4 inch wide Giant – 5 inch wide Padgett: Allow calibration while cutting is being

accomplished. Lighter and is easy to handle. Depend on glue applied to both the drum and skin

surface. Reese: It is a heavier instrument. Use an adhesive tape applied to drum and a glue

applied to skin surface.

FREEHAND CUTTING STSG All skin grafts are harvested with hand-held knives. These are – long, sharp blades with an adapter over

the blade that facilitate Cutting of the graft. Controlled the graft thickness. Allow cutting of very large pieces of skin. Edges of the skin graft donor site were always

irregular. Large Humby-type knives are less used today but

smaller knives are often helpful in cutting small grafts. Easy availability of Goulian-type knife or razor blade

should eliminate use of pinch grafts. These grafts were thick at the center and thin on the

edges.

MESH GRAFTS Primarily used in two situations When there is insufficient skin – as in massive

burn in which skin graft must be expanded.

When a very convoluted surface must be covered with a graft where a sheet might not adhere well.

Disadvantage – expanded one difficult in healing. Heal in b/w the expansion by epithelization. Does not prevent loss of a graft from hematoma, if

bleeding in profuse at the time of skin grafting. A semi-occlusive dressing is applied as there is Less tendency for the graft edges to curl as they dry. Less desiccation of the underlying wound.

GRAFT PLACEMENT Graft may be meshed by placing the graft on a carrier and

passing it through a mechanical meshing instrument. Allows expansion of the graft surface area up to 9 times the

donor site surface area. This technique is indicated when Insufficient donor skin is available for large wounds,

as in major burns or When the recipient site is irregularly contoured

and Adherence is a concern. Expansion slits Allow wound fluid to escape through the graft. Will not prevent graft loss due to underlying

hematoma. Heal by re-epithelialization and may contract

significantly.

Healed wound characteristically has a crocodile skin or checkerboard appearance.

Because of secondary contraction and poor cosmesis, avoid using this technique in the

Face, Hands, Over joints, and In other highly visible areas. Take care to prevent wrinkling or excessive stretching of

the graft. The graft must then be secured in place to provide stability

during initial adherence and healing.

COMPOSITE GRAFTS : Composite grafts are modified FTSGs consisting of

two or more tissue layers, usually composed of skin and cartilage.

INDICATIONS : Especially useful for repair of full thickness nasal

alar rim defects, nasal tip defects resulting in cartilage loss, columellar defects.

Repairing of full thickness nasal mucosal defects. Eyebrow reconstruction

DONOR SITES : The auricular donor sites

most commonly used are the helical crus, the helical rim, the antihelix, tragus and earlobe (skin and fat).

The helical crus provides a good contour for grafting of small alar rim defects because it is straight and does not have an anterior roll.

Procedure :The defect can be carefully measured and then

marked on the donor site, or a template can be

made. The recipient site on the alar rim must be de-

epithelialized and scar tissue removed to facilitate the amount of surface area that gets exposed to the graft.

The graft is sutured in layers, starting with the mucosal layer, using an absorbable suture. The needle should pass through the mucosa and then thorugh the graft edge, so that the knots are tied external to the graft.

An ointment – coated nasal packing can be placed gently in the nasal vestibule, and a light coat of antibiotic ointment and handherent (telfla) dressing are placed externally.

The perioperative use of antibiotics has been suggested because of the high bacterial colorization encountered in the perinasal area.

PINCH GRAFTS : There are small full-thickness grafts.Pinch graft can be harvested using Davol-Siman

dermatome or the weck blade. Pinch grafts have traditionally been used as wounds

that are draining. Treatment of the hypopigmentation in localized

areas of vitiligo.It is used for lining of a mastoid cavity following

radical mastoidectomy.

Technique : The donor skin is held with pickups and then lifted.

The elevated bit of skin is transected with iris scissors or a scalpel.

Multiple grafts (usually les than 1cm) are harvested and placed almost next to each other, and the spaces in between heal by epithelialization.

Disadvantage : The major drawback is the unsightly “HILLOCK”

surface irregularity when these grafts heal.

To overcome this drawback, Robinson proposed, punch biopsy to obtain a specimen of uniform depth by limitation of the downward force, thereby limiting the depth to the deep dermis.

Chondromucosal graftsAvasular grafts-cosists of nasal septum & mucosa.Useful for providing internal lining to replace the

conjunctive following total lower eyelid reconstruction.

Nasal septal cartilage replaces tarsal plate, mucosa replaces the conjunctiva.

Dermal & fat graftsWere formerly used for sunken defects around the orbit

& maxillary sinus following surgery.

GRAFT IMMOBILIZATION AND POST-OP CARE

In most cases of skin grafting – optimal dressing is bolus or tie-over dressing.

It is fashioned by placing sutures around the periphery to hold the graft onto the wound bed.

Facial sutures may be as close as 2 to 3 mm. Tied sutures gently press the dressing down onto the

skin graft, which in turn presses onto the wound bed. The main objective of the tie-over dressing is to

ensure contact b/w graft and host bed. SKIN GRAFT INLAY METHOD: Referred as the Stent dressing. Skin graft wrapped around dental compound, the

dermal side out.

Skin graft outlay technique is III but involves tying of sutures over the top of the combination of dental compound and skin graft.

OPEN TECHNIQUE Requires an Ideal wound bed, without bleeding or fluid

production. Cooperative or sedated patient. Limited motion is allowed to the patient. Graft usually is pink, adherent and viable within 48

hrs. Crusts appearing around the margin may be left in

place to allow natural separation.

WOUND CARE Superior dressings have been shown to be of the

semiocclusive variety. These products have been shown to have the

Fastest healing rates ( 9 days to re-epithelialization), Lowest subjective pain scores, Lowest infection rates (3%), and Are among the lowest in cost. Advantage of being transparent - allows ongoing

inspection of the site - maintaining sterility. Fluid collection - promotes moist wound healing - more

rapid healing rates and decreased subjective pain scores. The rate of healing is proportional to the number of epithelial

appendages remaining and inversely proportional to the thickness of graft harvested.

GRAFT SURVIVAL

Hair rarely grows from split-thickness grafts. Sweat glands and sebaceous glands initially degenerate

following grafting. Sensation returns to the periphery of the graft and proceeds

centrally. Split-thickness grafts reinnervate more quickly. Grafts may remain pale or white or may become

hyperpigmented with exposure to sunlight. It is generally recommended that the graft be protected

from direct sunlight for at least 6 months or even longer postgrafting.

SKIN GRAFT’ TAKE’After detaching of the skin graft from the donor site, it

becomes potentially a dead piece of tissue. Its life span ,when wrapped in gauze, moistened in

saline and stored in a fridge at 4 degree centigrade. It may be live for up to 3 weeks.

To survive permanently, it must be planted, become reattached and obtain a new blood supply from its new surroundings and the various processes involved in achieving this are called ‘TAKE’

“THE THINNER THE GRAFT, THE BETTER THE TAKE;

THE THICKER THE GRAFT, THE BETTER THE RESULT.”

GRAFT TAKEIs by fibrin and capillary buddingVascular bed is requiredGood opposition essentialWell- covered bone is needed.Is threatened by prior radiotherapyCan be destroyed by fibrinolysing bacteria.

A skin graft adheres to its new bed by fibrin.

Supplies the immediate nutritional requirements in the form of plasmatic circulation.

Outgrowth of capillary buds occurs that provide circulation of blood in the graft- demonstrated at 48 hours.

Fibers grow into the fibrin, which convert the adhesive clot into a more definite fibrous tissue attachment that increases over the ensuing days so that by 5 days reasonable anchorage has occurred.

Some organisms can destroy fibrin and prevent the fibrin to facilitate adhesion.

Beta hemolytic streptococcus pyogenes and staphylococcus aureus produces fibrinolysin.

FATE OF A SKIN GRAFT

PHASES OF SKIN GRAFT SURVIVAL.SERUM IMBITION PHASEGRAFT REVASCULARIZATIONORGANISATION PHASE:

SERUM IMBITION PHASE

When the graft is initially placed on the recipient site, it is devoid of vascular connections and depends on plasmatic circulation for fluid nourishment.

This nutrion is provided by plasma exudates from dilated capillaries in the host bed.

GRAFT REVASCULARIZATION

Immediately after application of the graft and during the subsequent 24 hours, the blood vessels of the grafts appear less filled with blood and are not readily detected when compared with those in the surrounding skin.

On the first day after grafting, many vessels in the donor tissue show early evidence of distention and are rapidly filled with static blood.

On the second day vessel distention

continues, but blood circulation has not

begun, although a sluggish flow of blood

may occasionally be seen in the peripheral vessels.

A slow flow of blood occurs in the graft

vasculature on the third or fourth day and continues to improve until the fifth or sixth day.

GRAFT REVASCULARIZATION

ORGANISATION PHASE:The fibrin clot fixes the graft to the host bed. On the fourth day after transplantation fibroblasts

infiltrate the fibrin net work.By the seventh or eight day fibroblast infiltration

continues as the fibrin clot is resorbed.Deep layers of the graft are anchored to the host bed

by the ninth day, with new vasculature and fibroblasts integrated in the firm union.

The nerve supply to a transported skin graft is completely served, leaving no sensation in the newly integrated graft.

Within 2 months, neural structures begin to regenerate. The nerve fibres enter the graft through the base and sides, following vacated neurilemmal cell sheaths.

DONOR SITE HEALING:

Full-Thickness grafts:These leave behind an open wound with no epithelial

remnants. Direct primary closure of the donor site after

undermining.

Split-thickness grafts:Within the first 24 hours, epithelium begins to grow

from the epithelial remnants in the dermis such as hair follicles, sebaceous glands, and sweat glands. Epithelial migration also occurs at the wound margins.

CAUSES OF GRAFT FAILURE : Inadequate graft bed (poor vascularity) Hematoma Movement Infection Technical errors such as placement over

epithelizing wound, grafts cut too thick or too thin, or upside-down graft

Poor storage of grafts.

BIOLOGICAL SKIN SUBSTITUTES

These biologic skin substitutes may be intended for Permanent replacement or As a temporary biologic dressing until Permanent solution is available or Normal skin regeneration and healing occur. Serve multiple functions Decrease bacterial counts and promote a sterile wound. Slow the loss of water, protein, and electrolytes. Reduce pain and fever, Help restore function, Facilitate early motion.

Provide coverage of vessels, tendons, and nerves.

Ideal skin substitute is one with

Little or no antigenicity,

Lack of toxicity,

Tissue compatibility, and

Lack of disease transmission.

Cadaveric grafts and pig skin grafts are the historical skin substitutes.

Cadaveric grafts: allografts or homografts - transplanted from one organism to another within the same species.

Pig skin grafts: xenografts or heterografts - transplanted from one organism to another of a different species.

The theoretical risk of disease transmission with cadaveric grafts also exists.

Cultured epithelial cells also have been developed, both as Autografts and Allografts.

Cultured epithelial autografts require biopsies of the patient, followed by growth of these cells in culture.

Disadvantage:

Structural weaknesses of

As well as the theoretical risk of disease transmission.

Allograft dermis :

Not actually rejected by the body because it is rendered immunologically inert during processing.

Body instead remodels and replaces it with a native dermal substitute.

Bilayer collagen matrices: Consist of a Porous spongelike lattice of bovine collagen,

Chondroitin-6-sulfate, and Glycosaminoglycans that serve as the dermal substitute

Dermal substitute layer serves as a scaffold that facilitates ingrowth of native fibroblasts and blood vessels with its eventual replacement.

An overlying silastic membrane simulates the epidermis and serves to seal the surface to reduce insensible fluid loss.

At about 3 weeks, the silastic layer may be peeled off and replaced with cultured epithelial cells or thin split-thickness skin grafts.

SKIN SUBSTITUTES

TYPES :Temporary - material designed to be placed on a fresh

wound (partial thickness) and left until healed. Semi-permanent - material remaining attached to the

excised wound, and eventually replaced by autogeneous skin grafts.

Permanent incorporation of an epidermal analog, dermal analog, or both as a permanent replacement .

AVAILABLE BIOLOGIC AND SYNTHETIC SKIN SUBSTITUTES

Naturally occurring tissues- Cutaneous allografts- Cutaneous xenografts- Amniotic membranes

Skin substitutes- Synthetic bilaminate- Collagen based composites       Biobrane       TransCyte       Integra

Collagen based dermal analogs- Deepithelized allograft- Alloderm

Culture-derived tissue- Bilayer human tissue (Apligraf)- Cultured autologous keratinocytes- Fibroblast seeded dermal analogs- Collagen-glycosaminoglycan matrix- Epithelial seeded dermal analog

Skin flaps

It is defined as tissue raised from donor site which is made up of skin & a variable amount of the underlying subcutaneous tissue but having its own blood supply.

It is used to reconstruct primary defect.

The transfer usually leaves a secondary defect

which is either closed by direct suture or covered with a free skin graft.

Types of flaps

Classification:

According to distance from the defect:

a. Local flaps

b. Distant flaps

Blood supply

c. Random

d. Axiali. Peninsular flaps

ii. Island flaps

iii. Free flaps

Tissue movement

e. Rotation

f. Advancement

g. Transposition

1.Axial pattern flap It is based on a named artery for majority of blood supply that runs within

the skin superficial to the underlying muscle layer, parallel to the overlying skin.

Good blood supply, because of which they can generally be raised to a much greater length. Limited by available vessels

Random flap at distal tip Examples

Nasolabial

Midline forehead flaps

2.Random pattern flapThey are based on the rich perforating vascular plexus of the skin.They are random in their blood supply, but also random in their

design.Most commonBased on subdermal plexusUnpredictable length:width of 3:1 or 4:1

Tissue movementRotation flap

A rotation flap requires that you make the defect into a triangle, and then swing the skin around.

It has to rotate on a pivot point, the radius of the arc of rotation being the line of the greatest tension.

Use rotation flaps on skin which has a good blood supply. They are particularly useful on the scalp, and

but are unsuitable below the knee where the blood supply is poor.

Make a rotation flap three times bigger than necessary, so as not to over estimate elasticity of the skin

INDICATIONS Scalp defectsLarge cheek defects greater than 3 to 4 cm in the

lower preauricular area where recruitment of the upper posterior cervical skin is required for wound closure.

CONTRAINDICATIONS

(1) Parts of the body where a patient’s

Skin is tight, or his circulation is poor, as in his hand and below his knee.

(2) Don’t make a rotation flap over bone

(other than the skull) or over tendon.

Advantages It has two only two sides ; thus, it lends itself to

placing one side in a border between aesthetic regions of the face.

The flap is broad based, there its vascularity tends to be reliable.

Great flexibility in the design & positioning of the flap.

Advancement flap

It refers to flap created by incisions that allow for a sliding movement of the tissue.

It best works in area of greater skin elasticity.

Types Unipedicle Bipedicle V-Y Y-V A-T Cheek advancement flap

Useful applications of advancement flaps Forehead Medial cheek Eyebrow Helical rim

Unipedicle advancement flap(U-plasty)Created by parallel incisions, which allow sliding

movement of tissue in a single vector toward a defect.

Triangular skin excisions along the periphery of the wound.

Typically are designed with a ratio of defect width-to-flap length of 1:3.

Bilateral unipedicle advancement flaps(H-plasty )

Helpful for repair of the central lips & chinDisadvantage is long suture line.

In both cases , advancement flaps are incised on opposite sides of the defect & advance toward each other.

Two flaps don’t necessarily have to be of the same length.

First incise & elevate only one flap.Advantage of bilateral flaps over a single flap for

repair of these midline structures is that equal pull from the two opposing flaps lessens tissue distortion & the propensity toward deviation of midline structures toward one side.

V-Y & Y-V advancement flap

A-T flapBilateral advancementtriangular defectUses - hairline, brow, lip

Bipedicle advancement flaps

For large defects of the scalp & defects of lower third of nose. It has 90-110 degree It is designed adjacent to the defect & is advanced into the

defect at a right angle to the linear axis of flap. This leaves a secondary defect –repaired with split -thickness

skin grafts or by direct closure 1:1 length is to width ratio should be followed

Cheek advancement Flap• Some rotation• Uses - medial cheek, nasofacial sulcus• Prevent complications (ectropion)

Transposition flapIt is made by moving a rectangle or square of skin

and subcutaneous tissue on a pivot point to cover an immediately adjacent defect.

The end of the flap should extends beyond the defect.

Linear axis Pivot pointVersatileRhomboid, dufourmental, bilobed

Advantages Its ability to harvest a flap at some distance from the

location of the defect.It can be designed in a number of configurations to

adapt to irregular-shaped defects.Ample quantities of subcutaneous fat may be left

attached to the under surface of the flap to assist with filing of deep facial defects.

Lengthy flap relative to the width of the base can be developed & this facilitates closure of the donor defect without excessive wound closure tension.

Disadvantage Potential for developing a trap–door deformity. This

complication tends to occur a few weeks following transfer.

ApplicationClassic designThe rectangle or parabola-shaped transposition flap

is commonly used for repair of cutaneous defects of the medial & lateral cheek, temple, & glabellar area.

Rectangle shaped transposition flaps

Island transposition

It is based on an axial blood supply can be harvested from the region of the forehead & medial cheek.

In the forehead, the flap is transferred with the supratrochlear artery & vein.

Rhombic flapsIt is used to repair a defect that has a configuration of a

rhombus with two opposing 60 degree & two opposing 120 degree interior angles.

The 60 degree to 120 degree can be thought of as two equilateral triangles placed base to base.

Dufourmental60 to 90 degree angles4 choices

Common skin & mucosal flaps in Oral & Maxillofacial Surgery

Nasolabial flapMedian forehead flapPalatal flap

Nasolabial flapAxial pattern - angular arteryInferior and superior flapsUses - lower 2/3 of nose, perinasal

area,upper lippin cushioning, blunting of nasofacialsulcuspotential ectropion, scleral show

Mid forehead flapIndian rhinoplastyMedian, paramedian forehead flapaxial patternSupratrochlear artery - at medial brow,

2cm from midlinepedicle can be as little as 1.2 cmthin distal tip appropriatelyDisadvantageslong scar, limited length, revision

Palatal flapPosteriorly based –ashe’s flapAnteriorly based – dharwad flapType of rotation flapBased on greater palatine vessels

Post operative carePain relieverWound carehydrogen peroxide, antibiotic ointmentSutures removed at 5-7 daysDirect sunlight avoided for 2-3 monthsDermabrasion - 6-12 weeksRevision/Irregularization - 6 months

Complications

Infection Hematoma/ seroma Cyanosis Failure/necrosis

CONCLUSION A working knowledge of the indications, techniques,

donor site considerations, and post-operative complications of all types of skin grafting is necessary for soft tissue reconstruction.

As the incidence of skin cancer continues to rise, increasing number of patients are likely to require reconstructive planning, and attention to detail preoperatively, intraoperatively and postoperatively, optimal cosmetic and functional results using skin grafting techniques can be achieved.

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