Wound Healing Phases

primary intention of wound closure

wound edges brought together and closed via surgery

secondary intention would closure

would left open and heals itself

time to heal is dependant on

wound depth, location and geometric shape

delayed primary intention closure

would edges are surgical closed after letting it heal a bit first

would healing phases

hemostasis, inflammation, proliferation, remodeling

hemostasis

forms clot to stop bleeding, initial matric

duration of hemostasis

immediately after injury for minutes

clot is composed of

fibrin mesh, aggregated platelets, embedded blood cells

importance of clot

provides initial mesh in wound matrix, prevents fluid and electrolyte loss, limits contamination

inflammatory phase

bring inflammatory cells to wound site, transition of vasoconstriction to vasodilation, control bacteria and debris

characteristcs

erythema, heat, edema, pain

duration of inflammatory phase

0-6 days post injury

inflammatory phase includes what cells

platelets, mast cells, neutrophils and macrophages

proliferative phase

granulation tissue fills wound, angiogenesis, epithelization, wound edges contract (all simultaneously)

proliferative phase cells

fibroblasts and GF, myofibroblasts, GAGs, proteoglycans

collagen is set initially in what form

type 3 then organizes to becomes type 1 later

granulation (proliferative phase)

laying down ECM, red/beef looking tissue

angiogenesis (proliferative phase)

re-establishes vascular supply to new tissues, day 2 onward

epithelialization (proliferative phase)

re-establish barrier, cell migration and proliferation to rebuild, day 1 onward

remodeling phase

collagen maturation and reorganization, pink/light tissue, would is closed but not healed, strength increases via collagen synthesis

duration of remodeling phase

day 8-years

scar tissue strength

70-80% as strong as original tissue

remodeling phase primary cells

fibroblasts, growth factors, MMPs, TIMPs

remodeling is essential to formation of a

strong scar

MMPs

tissue breakdown to clear the way for cell migration

growth factors

complex proteins promoting cell growth, division, migration and recruitment into injured tissue

growth factor is released in

all phases of wound healing

acute wound

heals within an expected timeframe

chronic wound

fails to heal within expected timeframe (can be chronic the moment it occurs)

chronic wounds are most commonly stalled in the

inflammatory phase

chronic wounds are associated with

repeated trauma, poor perfusion, excessive inflammation, comorbidities

chronic wounds commonly have

senescent cells, metabolically active but not doing anything

intrinsic factors impacting healing

chronic disease, immunosuppressive therapy, perfusion, age, neurologically impaired skin, malnutrition, wound extent and duration

extrinsic factors impacting healing

medications, nutrition, chemo, bioburden, foreign body, stress

iatrogenic factors impacting healing

local ischemia, inappropriate wound care, physical technologies