*Plastics Flashcards
CREEP
INCREASE IN STRAIN seen when skin is under CONSTANT STRESS
occurs in a matter of minutes and is due to extrusion of fluid from the dermis and a breakdown of the dermal framework
Stress
force applied per cross-sectional area
F/A
Strain
CHANGE IN LENGTH divided by the ORIGINAL LENGTH of a given tissue when a force is applied
Stress Relaxation
the decrease in stress when skin is held in tension at a constant strain for a given time;
this occurs over a matter of days to weeks and is due to an increase in skin cellularity and the permanent stretching of skin components
what is good “take” of a graft?
- absence of infection
- perfect hemostasis
- good dressing
- absence of motion
how does thickness of graft affect “take” and function?
- thinner the graft, the better the “take”
- the thicker the graft, the better the function
which part of amniotic tissue allografts are known to contain maternal antigens?
Chorion layer: on the maternal side of the placenta; contains maternal antigens
Theory is that by removing chorion layer, less likely to have host rxn
(other side is Amnion)
which side is against the wound in amniotic tissue allografts?
STROMAL side down against wound (Sticky and gelatinous side)
as compared to smooth/shiny epithelial surface
amniotic membrane components
- structural collagen: type I, 3, 4, 5, 7
- ECM proteins: Fibronectin, proteoglycans, glycosaminoglycans
- Growth factors: EGF, TGF, FGF, PDGF, VEGF
- Regulating proteins: MMPs, TIMPs, IL-K
Amniotic Membrane Allografts:
benefits
examples of Amniotic Membrane Allografts
affinity, amniofix, biofix, epifix, grafix, neox, nucel, nushield, revitalon, xwrap
compare FTSGs and STSGs
reasons for skin graft failure
Transpositional Flap
Rotational Flap