Skin Flaps and Grafts

Question 1

Skin Flap (aka pedicle graft or pedicle flap)

Answer 1

• Portion of skin and subcutaneous tissue with a vascular__ attachment moved from one area of the body to another
• Blood flow is maintained or immediately re-established when skin segment is moved to new position

Question 2

Skin Graft

Answer 2

• A segment of skin that is completely removed from the body and transferred to a recipient site
• Blood supply is severed and new vessels must grow in from recipient site

Question 3

Indications for skin flaps

Answer 3

• Defects with poor vascularity
• Areas difficult to immobilize
• Defects overlying cavities (ex orbit)
• Areas where padding and durability essential

Question 4

Skin graft indications

Answer 4

• Major loss of skin (trauma, tumor removal)
• Distal extremities
• Full-thickness burns

Question 5

Skin Flap Classification

Answer 5

1. Location
   
   1. Distant from the defect
   2. Adjacent to defect
2. Blood supply
   
   1. Subdermal plexus flaps
   2. Axial pattern flaps
3. Tissue types
   
   1. Just skin and subcutaneous tissue
   2. +/- muscle, cartilage, and bone

Question 6

Axial pattern flaps

Answer 6

• Blood supply from direct cutaneous artery and vein
• Excellent blood supply!!!

Question 7

Subdermal plexus flaps

Answer 7

• Blood supply from subdermal plexus - from terminal branches of direct cutaneous artery
• Includes all other types of flaps

Question 8

Local flaps - flaps that rotate around a pivot point

Answer 8

• Rotation flaps
• Transposition flaps

Question 9

Local flaps - flaps that do not rotate around a pivot point

Answer 9

• Single pedicle advancement flaps
• Bipedicle advancement flaps
• H-plasty flaps
• V-Y advancement flaps

Question 10

Rotational flaps

Answer 10

• Local flaps are pivoted over a defect.
• Flap and defect share a common border!
• Create incision in stepwise fahsion until no tension

Question 11

Transposition flaps

Answer 11

• Rectangular flap created within 90 degree of the long axis of the defect
• Width of flap = width of defect
• Note the effect of rotation on flap length - will decrease flap length

Question 12

Interpolation Flaps

Answer 12

• Rotating rectangular flap that lacks a common border with the skin defect
• Flap covers skin between donor and recipient
• Second surgery to excise redundant skin
• *you leave the pedicle intact - otherwise it would be considered a skin graft

Question 13

Single-Pedicle Advancement Flaps

Answer 13

• One of the most commonly used in vet med
• Formed in loose, elastic skin and slid over the dfeect
• Flap incisions made parallel to lines of least tension!

Question 14

H-plasty (bi-pedicle advancement flaps)

Answer 14

• two advancement flaps coming from either direction to meet eachother in the middle
• Cut triagnles out again to prevent dog ear effect
• As it comes together, sutured at an H

Question 15

Pouch, hinged, and tube pedicle flaps

Answer 15

• Location - distant flaps (skin still stays on pedicle!)
• Blood supply - subdermal plexus
• Multi-stage procedures
• Used more for lower extremity skin defects

Question 16

Pouch Flaps

Answer 16

• Create two incisions - undermine - then give a dog or cat a pocket to stick the paw in
• Secondary surgery - excise area of pouch that had been left in tact
• Excise dorsal and ventral margin
• Then close the original wound

Question 17

Tubed Pedicle Flaps

Answer 17

• Two parallel incisions - sutured to eachother around tube
• Closing up the wound underneath the tube
• Tube needs to heal entirely (10-14 days)
• Tube of skin hanging off the patient - excise upper/proximal portion of the tube and walk tube down to area of interest

Question 18

Axial Pattern Flaps

Answer 18

• Flaps that include a direct cutaneous artery and vein at the base of the flap
• Advantage: able to transfer large skin segments in a single stage without the need for delay procedure
  
  • Already have an excellent blood supply, better flap survivial
• Disadvantage: limited on areas of the body that these flaps can be developed

Question 19

One of the most commonly used axial pattern flaps is:

Answer 19

Caudal superficial epigastric axial pattern flap

Question 20

Caudal superificial epigastric axial pattern flap

Answer 20

• Ventral midline is medial incision
• Lateral incision is parallel to the first, at a distance equal to the distance from the mammary teats to the midline
• I.e - teats will be the midpoint of the flap
• Cranial extent is between 1st and 2nd glands

Question 21

Major points when planning skin flaps

Answer 21

• Base of flap too narrow = flap necrosis
• Flaps fixed to recipient bed without tension
• Ideally, plan so color and direction of hair growth matches recipient bed

Question 22

Thoracodorsal axial pattern flap

Answer 22

• Defects involving the shoulder, forelimb elbow, axilla, and thorax (down to carpus in cat)
• Cranial border will be the scapular spine
• Caudal border parallel to spine twice the distance from the acromion to the caudal shoulder depression

Question 23

Successful skin graft healing

Answer 23

• Depends on:
  
  • Establishment of arterial connections
  • Adequate drainage
• Recipient bed:
  
  • Healthy granulation tissue
  • Free of infection or debris
• Grafts will not take:
  
  • Bone, cartilage, tendon or nerves
  • Infection, crushed tissues, irradiated tissues, avascular fat, chronic ganulation tissue

Question 24

Acceptance of grafts

Answer 24

• Plasmatic imbibition
  
  • Serum-like fluid and cells pulled from the recipient bed into the graft vessel
  • Nourishment of the graft
  • Edema for 48-72 hours
• Inosculation
  
  • Anastomosis of recipient bed vessels with graft
  • 24-72 hours
• Vascular ingrowth
  
  • From the bed into the graft
  • 48 - 72 hours

Question 25

Full-thickness grafts

Answer 25

• Consists of epidermis and dermis
• Includes hair follicles and adnexal structures
• Best cosmetic appearance and function
• Most common in vet med

Question 26

Recipient bed preparation

Answer 26

• Lightly scrape with scalpel blade to remove surface debris and exposure capillaries
• Cover bed with moist sponges soaked in CHX solution while graft is being prepared

Question 27

Mesh Grafts

Answer 27

• Pros
  
  • Allows expansion of graft to cover larger defects
  • Allows drainage of blood and serum from under graft
  • Allow graft to conform better to uneven structures
• Application
  
  • Suture or staples on all free edges and midline

Question 28

Answer 28

Punch grafts

Question 29

Donor site of skin grafts

Answer 29

• Typically taken from the dorsal or lateral trunk
• Close or treat as open wound

Question 30

Post-op care for skin grafts

Answer 30

• Apply antibiotic ointment and nonadherent dressing (adaptic)
• Absorbent secondary layer
• Protective tertiary layer
• Splint or cast if over joint
• Change dressing in 72 hours, then daily