Granulation Tissue and Skin Grafting Flashcards
What is the difference in wound healing on the body vs the limb?
Body: more efficient contraction
Limb: slow healing due to increased motion and decreased vascularity
What is proud flesh?
Excessive granulation tissue
What factors limit the distal limb wound healing process?
No muscle, no excessive tissue, close to contamination, constant movement
What types of wound healing are best for preserving function and cosmetic appearance?
Primary and delayed primary
What is the treatment indicated for proud flesh?
Resection & bandage + delayed secondary closure
Why does proud flesh occur?
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)
What are the most common areas for granulation tissue formation?
Metacarpus and metatarsus
What is a crucial step in determining if grafts will fail or not?
Granulation bed preparation- needs to be healthy, flat, no hematomas and no fissures
What antibiotic is commonly used to ensure that there is a healthy wound bed?
Ticarcillin- works well against pseudomonas
What are the two classifications of skin grafts?
Pedicle graft: remains connected to donor site
Free graft: completely separated from blood supply (most common)
What is the difference of a full thickness vs. split thickness graft?
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
Autograft
Skin graft from same animal on a different piece of the animal’s body
Ex: equine amnion
Allograft
tissue graft from a donor of the same species as the recipient but not genetically identical.
Ex: equine amnion or bandaging
Xenograft
Donor of a different species
When should graft acceptance occur?
Within the first 5 days
What allows for adherence of skin grafts?
Fibrin
When does inosculation and neovascularization occur?
Inosculation: 48 hrs.
Neovascularization: 4-5 days
What are the three types of island grafts?
Tunnel, Punch and Pinch (seed)
what are the pros and cons of punch and pinch grafts?
Pros: GA not required, minimal equipment, technical expertise minimal, complete failure rare
Cons: poor cosmesis, little hair regrowth
Which graft is the easiest to use and harvest with high success rate?
Punch graft
Where are punch grafts harvested from?
Under mane or ventrolateral abdomen
What needs to be done when making skin grafts?
Excise SQ fascia and fat
Why are recipient holes made in grafts?
allows hemostasis to occur
place 6 mm apart in symmetrical pattern (recipient holes must be smaller than donor holes)
Why must recipient holes be made with smaller punch biopsy than the graft?
Wound contraction
How is a pinch graft performed?
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
What are the names of the instruments used for split thickness sheet grafts (hand vs. drum dermatomes vs. power)?
Hand: watson knife
Drum: padgett manual dermatome
Power: stryker electric and brown pneumatic dermatome
Why should sheet grafts be meshed?
Prevents fluid from disrupting graft from fibrinous and vascular attachments
Which direction should grafts be secured to the wound?
Towards the wound margin
What is the most important factor for survival of the graft?
prepping the recipient site for grafting
Granulation tissue flush w/ skin and topical antibiotic 24-48 hrs. prior to grafting (Ticarcillin)
What are some aspects for aftercare of grafting?
Cover w/ sterile non-adherent dressing, secure w/ sterile elastic confirming rolled gauze
What are the three main reasons for graft failure?
Hemorrhage
Motion
Infection
What must occur to prevent fluid accumulation?
Graft must contact the wound to prevent hemorrhage (fluid accumulation in general)
What prevents fibrin from attaching graft to the wound?
Hematoma/seroma
What antibiotic should be used to prevent infection in equine?
Ticarcillin
What two bacteria can infect a wound with lower concentrations than 10^5?
B-hemolytic strep & Pseudomonas
T/F: you can’t graft a wound that has signs of inflammation
TRUE
