Granulation Tissue and Skin Grafting

Question 1

What is the difference in wound healing on the body vs the limb?

Answer 1

Body: more efficient contraction
Limb: slow healing due to increased motion and decreased vascularity

Question 2

What is proud flesh?

Answer 2

Excessive granulation tissue

Question 3

What factors limit the distal limb wound healing process?

Answer 3

No muscle, no excessive tissue, close to contamination, constant movement

Question 4

What types of wound healing are best for preserving function and cosmetic appearance?

Answer 4

Primary and delayed primary

Question 5

What is the treatment indicated for proud flesh?

Answer 5

Resection & bandage + delayed secondary closure

Question 6

Why does proud flesh occur?

Answer 6

Inefficient protracted inflammatory phase results in excessive proliferation phase

Fibroblasts maintain synthetic role and don’t differentiate into myofibroblasts
PMN/Neutrophils #’s stay higher in horses for longer- chronic inflammation
PMNs= pro-fibrotic state=exuberant granulation tissue (delays healing)

Question 7

What are the most common areas for granulation tissue formation?

Answer 7

Metacarpus and metatarsus

Question 8

What is a crucial step in determining if grafts will fail or not?

Answer 8

Granulation bed preparation- needs to be healthy, flat, no hematomas and no fissures

Question 9

What antibiotic is commonly used to ensure that there is a healthy wound bed?

Answer 9

Ticarcillin- works well against pseudomonas

Question 10

What are the two classifications of skin grafts?

Answer 10

Pedicle graft: remains connected to donor site

Free graft: completely separated from blood supply (most common)

Question 11

What is the difference of a full thickness vs. split thickness graft?

Answer 11

Full thickness: epidermis and ENTIRE dermis; best for cosmetic and hair growth but not as resilient due to more dermis (GENERAL ANESTHESIA REQUIRED)
Split thickness: epidermis and portion of dermis, amount of dermis directly proportional to the graft’s durability, require dermatome, more available vasculature

Question 12

Autograft

Answer 12

Skin graft from same animal on a different piece of the animal’s body
Ex: equine amnion

Question 13

Allograft

Answer 13

tissue graft from a donor of the same species as the recipient but not genetically identical.
Ex: equine amnion or bandaging

Question 14

Xenograft

Answer 14

Donor of a different species

Question 15

When should graft acceptance occur?

Answer 15

Within the first 5 days

Question 16

What allows for adherence of skin grafts?

Answer 16

Fibrin

Question 17

When does inosculation and neovascularization occur?

Answer 17

Inosculation: 48 hrs.
Neovascularization: 4-5 days

Question 18

What are the three types of island grafts?

Answer 18

Tunnel, Punch and Pinch (seed)

Question 19

what are the pros and cons of punch and pinch grafts?

Answer 19

Pros: GA not required, minimal equipment, technical expertise minimal, complete failure rare
Cons: poor cosmesis, little hair regrowth

Question 20

Which graft is the easiest to use and harvest with high success rate?

Answer 20

Punch graft

Question 21

Where are punch grafts harvested from?

Answer 21

Under mane or ventrolateral abdomen

Question 22

What needs to be done when making skin grafts?

Answer 22

Excise SQ fascia and fat

Question 23

Why are recipient holes made in grafts?

Answer 23

allows hemostasis to occur

place 6 mm apart in symmetrical pattern (recipient holes must be smaller than donor holes)

Question 24

Why must recipient holes be made with smaller punch biopsy than the graft?

Answer 24

Wound contraction

Question 25

How is a pinch graft performed?

Answer 25

Use a needle and #11 blade

Tent skin w/ burred needle or forceps, transect 3 mm disc w/ #11 blade, store on saline moistened gauze

Question 26

What are the names of the instruments used for split thickness sheet grafts (hand vs. drum dermatomes vs. power)?

Answer 26

Hand: watson knife
Drum: padgett manual dermatome
Power: stryker electric and brown pneumatic dermatome

Question 27

Why should sheet grafts be meshed?

Answer 27

Prevents fluid from disrupting graft from fibrinous and vascular attachments

Question 28

Which direction should grafts be secured to the wound?

Answer 28

Towards the wound margin

Question 29

What is the most important factor for survival of the graft?

Answer 29

prepping the recipient site for grafting

Granulation tissue flush w/ skin and topical antibiotic 24-48 hrs. prior to grafting (Ticarcillin)

Question 30

What are some aspects for aftercare of grafting?

Answer 30

Cover w/ sterile non-adherent dressing, secure w/ sterile elastic confirming rolled gauze

Question 31

What are the three main reasons for graft failure?

Answer 31

Hemorrhage
Motion
Infection

Question 32

What must occur to prevent fluid accumulation?

Answer 32

Graft must contact the wound to prevent hemorrhage (fluid accumulation in general)

Question 33

What prevents fibrin from attaching graft to the wound?

Answer 33

Hematoma/seroma

Question 34

What antibiotic should be used to prevent infection in equine?

Answer 34

Ticarcillin

Question 35

What two bacteria can infect a wound with lower concentrations than 10^5?

Answer 35

B-hemolytic strep & Pseudomonas

Question 36

T/F: you can’t graft a wound that has signs of inflammation

Answer 36

TRUE