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Skin Flaps and Skin Grafts

STUDY
PLAY
Skin Flap vs. Skin Graft
Flap - Blood supply is maintained or immediate re-established
Graft - Blood supply is severed
Classifications of Skin Flaps
Either by:
1. Type of blood supply
Subdermal Plexus
Axial Pattern Flaps
Revascularized - re-attchement of blood vessels
2. Distance from wound
Local - usually subdermal plexus flaps
Distant - usually axial pattern flaps
Sub dermal plexus flaps
Also called Random base flaps
- Cutting into tissue w/ out knowing how strong the blood supply you are bringing is
Length : Width ration - do not exceed 3:1
- anything larger you risk losing blood supply
Axial Pattern Flaps
A type of transposition flap
Incorporate direct cutaneous artery and vein
Most commonly used vessels:
Thorcodorsal
Caudal Superficial Epigastric
Considerations when using the caudal superficial epigastric
Vessels in the female are more developed
Ipsilateral flap (same side) - can increase the distance the flap can extend, but risk kinking the blood supply
Contralateral flap - shorter distance, but less risk of compromising blood supply
Recommend spaying female, when doing these flaps
- the glands and nipple/thelium are still functional
Techniques commonly done with axial pattern flaps
1. Bridging incision
2. Tubing the flap - distant flap
Bridging Incision
Have to make an incision between the flap and the lesion
Tubing the flap
Cut the flap free in 2-3 weeks
This eliminates having to make a bridging incison
Blood supply used in local flaps
Subdermal plexus
Local flaps that rotate about a pivot point
1. Rotational flaps
2. Transposition flaps
Rotation flaps
Loose skin is rotated into the defect by cutting an arching incision on one side of defect
Arching incision needs to be 2.5x the width of the defect
A back cut incision increases the motility of the flap but also increases the risk of vascular compromise
Multiflap rotational flaps
2 or more rotational flaps
A 3 point suture line is NEVER ideal
Transposition flaps
3 sided flap
Donor skin is in a different plane from the wound
60-90 degrees is most common
Complication of transposition flaps
"Dog ears"
A small pucker of the skin that occurs when the edge of the skin doesn't quiet align
Small dog ears usually resolve during healing
Large ones should be removed at time of closure - easiest way is the lift up the tissue of the dog ear, cut through it parallel to the primary incision
Local flaps that do not rotate about a pivot point
1. Single pedicle advancement flap
2. Bipedicle advancement flap - not commonly used
Single pedicle advancement flap
Skin adjacent to the wound allows you to mobilize it to the wound
Common locations:
Dorsum, Ventral neck, Small flaps for eye lid reconstruction
Good trick is to angle your incision outward as you cut back, enhances likelihood you will bring good blood supply
Bipedicle advancement flap
Also called and H-plasty
Rarely used in small animals
Used more commonly in large animal medicine
Can be done w/ or with out Burrow's triangles (see picture)
Distant flaps
1. Tubed pedicle flaps
2. Pouched flap/Single pedicle direct flap
Tubed pedicle flap
Pouch Flap/Single direct pedicle flap
Distal limb wound is covered by skin on the trunk by bringing the limb to the flap
The limb should be sutured to the trunk PRIOR to creating the flap
- helps make location for the flap
- by finding the most comfortable position for the limb
Limb is in place for 10 days, ideally 14days
Need to close the skin beneath the flap as much as possible to avoid weepage
The limb is freed from the trunk with the flap attached.
Complications of Flaps
Flap edema - kink vessel
Seroma - put a light pressure wrap on it to stabilize it
Infection
PArtial deshisence - dehisences at corners d.t. severe edema
Vessel thrombosis w/ flap loss - if the flap gets back we need to take it out
Managing a compromised flap
Assess the vascular integrity
Vasoactive drugs??? - helps
Hyperbaric oxygen - works well
Leaches - used for venous compromise if you have blood accumulating under the flap
- not as good as they say they are
Indications for skin grafts
1. Skin defects on extremities
2. Excessive burn wounds
3. Adjunct to other reconstructive procedures
Classification
1. Donor-Host relationship
- Autograft
- Allograft
- Xenograft
2. Thickness
- Full thickness
- Split thickess
Definitions
Autograft - from the same patient - MOST USEFUL
Allograft - same species
Xenograft - different species
Full thickness vs. Split thickness skin grafts
Full thickness
- Epidermis and dermis, thus includes hair follicles and adnexa
- Most commonly used
- Best cosmetic appearance
Split thickness
- Epidermis and up to 2/3 dermis
- More commonly used in equine
Recipient bed should be
1. Healthy granulation tissue
2. Fresh wound w. sufficient blood supply to produce granulation tissue
- Healthy muscle is best
Areas where skin grafts will not take hold
Over tendons
Over missve amounts of fibrous tissue
When is granulation tissue ready for grafting?
1. When it is pink and glistening
2. Surface is smooth
3. Wound is contracting and epithelial migration is visible at wound margin
Preparation of recipient bed
1. Lightly scrap w/ scalpel blade to remove surface debris and expose capillaries
2. Cover bed w/ moist sponges soaked in CHX solution while graft is being prepped
Harvesting full thickness skin grafts
Dissect graft from donor site deep to the cutaneous trunci muscle

Remove cutaneous trunci muscle and superficial subcutaneous tissue prior to apply graft
- Important step, it enhanced revascularization of the graft

Can take off C. trunic and SQ tissue by placing sutures and using hypodermic needles to stretch the graft back to original size
Bulbs of the hair follicles should be visible if graft is properly prepared
- has a cobble stone appearance
A pattern is made for skin grafts when
1. Recipient site has irregular boarders
2. When exact fit is desired
Skin Graffting Techniques
1. Sheet
-Full thickness
-Spilt thickness
-Mesh, sieve, pie crust
2. Punch
-Seed or pinch
-Stamp
3. Strip
-Tunnel
Mesh, sieve, or pie crust grafts
Sheet grafts with parallel rows of staggered slits
Slight difference between these types based on the number of holes
Advantages of Mesh, Sieve or Pie crust grafts
1. Allows expansion of graft to cover larger area
2. Allows drainage of blood and serum from under the graft
3. Allows the graft to conform better to uneven surface
Mesh dermatome
A machine that allows us to make the mesh incisions very quickly and easily
Number of holes and length of slits determines
the degree the mesh graft can be expanded
Punch/Stamp/Seed/Pinch Graft
More commonly used in large animals
Not commonly used in small animals
Full thickness plugs of skin placed in the granulation bed to enhance epithelialization
- seeds epithelialization by minimizing wound surface area and increasing viable epithelium
Results in poor cosmetic appearance
Punch graft harvest and placement
Harvested using a punch tool 1 size larger than tool used to make holes i granulation tissue - accounts for contraction of the harvested graft
Remove m. and SQ tissue and prep recipient holes similar to other types of grafts
Graft application
As soon as the graft is placed it forms a fibrin seal - will feel stuck by the end of the procedure
Graft is thoroughly adhered after 48 hrs

Edges sutured and a few throws are but in the filed of the graft
Pass through the already present slits to avoid doing more damage
Closure of the donor site
Take a graft from a site which can be easily closed w/ walking sutures
Post op care
1. Apply AB ointment and no-adherent dressing to avoid an overgrowth of normal flora
2. Place a secondary absorbent layer followed by a cast or splint to keep immobilized
3. Change dressing in 24-48 hrs
Post op changes in healing grafts
Initially it may appear swollen
Later at 7 days PO it may look a bit nasty - take a wait and see attitude
Occasionally it looks great right away