Wound Healing

• protein precursor to filaggrin
• found in the s. granulosum

acts as glue to stabilize s. granulosum

• large amount of protein-bound lipids
• s. lucidum

s. spinosum

• specialized appendages regulating:
• -temperature
• -evaporation
• -touch
• -pain stimuli

• Adnexa include:
• -hair follicle
• -apocrine sweat glands
• -eccrine sweat glands
• -sebaceous glands
• -nerves of epidermis

• Separated from epidermis by basement membrane
• Intricate connective tissue network 75% collagen
• Elastic 
• Accommodates:
• -Nerve bundles
• -Sensory receptors
• -Lymphatic's
• -Vascular elements

• Maintains structural integrity of dermis
• Vital to wound healing & scar formation
• Synthesize connective tissue proteins for collagen & elastin
• Synthesize ground substance matrix for glycosaminoglycans

• Related to underlying musculature & osseous structures
• Associated with creases in the skin with normal flexion and extension
• Greatest ability to stretch and relieve tension in perpendicular direction to RSTL
• Not greatly defined in foot and ankle
• Lines of maximal and minimal movement
• Very important in incisional approach and wound healing
• If an incision is placed perpendicular to RSTL then maximum tension = stretched and hypertrophic scar
• Incisions parallel or within RSTL = less tension and scarring
• If cannot be within RSTL make incision in an oblique fashion

• If allowable incision should be within RSTL
• If not attempt for oblique to RSTL
• If crossing a joint try and curve incision
• Consider preoperatively:
• -Skin characteristics
• -Underlying anatomic structures
• -Location of incision

wood

• 130 mmHg continuous
• Sub atmospheric pressure
• Utilizes negative pressure to promote wound healing.
• Wound dressing “open cell” foam surface to promote granulation tissue.
• Can be used for variety of chronic and acute wounds

• Can be used to promote granulation tissue
• Stimulates angiogenesis.
• Oxygenation levels greater than 40mm Hg required for wound healing.
• Less than 30mm Hg results in impaired oxygenation and decreased wound healing.
• HBO increases oxygenation to soft tissues.
• Improves neutrophil function, facilitates fibroblast cell division, increases collagen formation, and increases capillary budding

10^5

85%

staph and strep

2.1%

• receptive host
• contamination of microorganisms
• wound culture medium

PDGF and TGF-B

• FGF
• Interlukin-1
• Tumor necrosis factor alpha

• 1. Hemostasis: instantly- minutes
• 2. Inflammation(Substrate): Last 5-7 days
• 3. Proliferative: Day 5-21
• 4. Remodeling: 3 wks- 1 year

• Begins at incision/injury
• Lasts 5-7 days
• Neutrophil migration
• Macrophage migration
• Cytokine secretion and recruitment of fibroblasts and endothelial cells

24 hours

• 5-21 days
• Fibroblast migration and proliferation
• Collagen deposited
• Endothelial cells assemble microvascular structures
• Glycosaminoglycans make up the connective tissue matrix
• Loose matrix of collagen, fibronectin and hyaluronic acid

1 week

• ≈3 weeks – 1 year
• Lattice like collagen network
• Laying down of scar tissue
• Transformation of capillaries and fibroblasts to relatively acellular type I collagen bundles

small wounds

following 3-4 days

-Begins within hours of injury

-Initiated by platelet release of epidermal growth factor

-Begins at wound edge and migrates centrally

›-Continues until epidermal surface is completely restored

• unstable quality of final wound and fragility
• *any for of minor trauma can cause recurrent ulceration

60 days post injury

80%

delay fibroblastic activity--> decreased wound strength

• Ascorbic acid
• Vit C and iron are required for hydroxylation of lysine and proline (collagen)
• Vitamin C and Lysine which crosslink and stabilize the triple helix structure of collagen

• retinoic acid
• modulates collagen production and degradation

• potent antioxidant
• alpha tocopherol
• accelerate dermal and bone healing

deficiency related to poor wound healing if deficient

• decrease in phagocytosis
• decrease in killing of bacteria

›-Microvascular disease 

›-Decreased host resistance to bacteria

• ›-Metabolic differences – hyperglycemia and
• insulin deficiency/resistance

• ›-BS > 200mg/dl = ↓ phagocytosis and
• decreased killing of bacteria

›-Insulin deficiency = ↓ collagen production and wound tensile strength

›-Decreased fibroblast reproductive capability

decrease collagen production and wound tensile strength

• Infection: 
• ›-Competes with new tissue for nutrients and oxygen
• ›-Lactic acid production lowers pH and furthers tissue breakdown

• ›Smoking!
• -vasoconstrictive effect due to nicotine

decreased oxygenation

›Inhibit cellular proliferation 

›Inhibit tissue growth

›Inhibit inflammatory reaction

›Inhibit fibroblasts proliferation

›Inhibit epithelization

›Reduce collagen production

• Steroids break down tissue fat and proteins and
• thus inhibit cellular proliferation, tissue growth and DNA synthesis.

inflammatory stage

›Iodophor

›Acetic acid

›Hydrogen peroxide

-Cytotoxic to bacteria and host tissue 

-›Retards wound epithelialization

-›Can lead to necrosis and decreased microcirculation

›-May allow invasive flora to overtake normal inhibitory flora of wound

›Blocks  formation of vitamin K and vitamin K dependent clotting factors

inactivate thrombin inhibiting blot clotting

decreases platelet aggregation

fluid that filters from circulatory stem to a wound

• plasma proteins
• WBC
• RBC
• Platelets

• Dilute toxins of dead cells
• limit use; prevents additional injury
• provide blood cells and nutrients to site of injury
• carry away toxins and waste

• mild inflammation
• usually clear
• little protein
• like water

-Infections

-Neutrophils

›-Fibrinogen

›-Necrotic tissue

›-Yellow to green

›-Thick

›-Often has odor

• Fibrinogen and fibrin
• white to yellow in color
• thin

• RBC
• Thick

release of cytokines in acute phase

migration of neutrophils to phagocytose debris