Wound Healing and Closure

Skin Electro Polarity Balance

  • The skin is the largest organ and has an electric charge.
    • Epidermis: negative charge.
    • Dermis: positive charge.
  • Wound (involving dermis - partial or full thickness):
    • Becomes positive due to macrophage secretions.
    • Disrupts charge differences, triggering wound healing.
  • Superficial wounds (epidermis only):
    • Heal by keratinocyte regeneration from the basement membrane.

Normal Wound Healing Process (Partial or Full Thickness)

  • Three overlapping phases:
    • Inflammation.
    • Proliferation.
    • Maturation/Remodeling.

Inflammation Phase

  • Duration: Few days to a week (average).
  • Body's initial response to clean the area.

Proliferation Phase

  • Duration: Four to twenty-five days (can overlap with inflammation).
  • Further cleaning and rebuilding of tissues.
  • Wound fully closes.

Maturation/Remodeling Phase

  • Duration: Twenty days to years (depending on wound).
  • Wound regains strength, mostly scar tissue.
  • Final phase of healing.

Inflammation (Inflammatory Phase)

  • Focus on general actions, not cellular/chemical details.
  • Important for cleaning and preparing for subsequent phases.
  • Involves vascular and cellular response to injury.
  • Goals:
    • Control bleeding.
    • Prevent infection.
    • Clean dead tissue/debris.
    • Prepare for proliferative phase.
  • Duration: About a week, can be prolonged.
  • Can get stuck if the wound is contaminated; cleaning techniques can help it progress to the next phase.

Inflammation - Cardinal Signs

  • Excess heat.
  • Redness.
  • Swelling.
  • Pain.
  • Loss of function (if extensive).

Proliferation Phase

  • Primary phase for wound closure.
  • Begins within 48 hours in healthy individuals, typically 72 hours to 3 weeks.
  • Rapid cell growth, extracellular matrix formation.
  • Wound resurfaces from the bottom up and edges inward.
  • Four stages:
    • Angiogenesis: Creation of new capillaries (small red dots, rosy pink).
      • Brings nutrition, removes waste.
    • Granulation Tissue Formation: Vascularized connective tissue.
      • Provides scaffolding for fibroblast migration.
      • Fibroblasts become scar tissue or myofibroblasts (for wound closure).
    • Epithelialization: Epithelial cells (skin cells). Keratinocytes in the epidermis.
      • Multiply and migrate across the wound bed.
      • Requires granulation tissue, a moist and clean wound.
      • Slower if too dry or too wet.

Maturation/Remodeling Phase

  • Final phase of wound healing.
  • Wound is completely resurfaced.
  • Duration: Three weeks to two years post-injury.
  • Greatest change occurs between 6-12 months.
  • Collagen fills and resurfaces the wound; fibers reorient along stress lines.
  • Scar massage and range of motion can help realign collagen fibers.
  • Scarring is about 80% of original skin strength and elasticity.
  • Full/partial thickness wounds may have decreased sweat glands, sensation, melanin, and hair follicles.
  • Coloration changes with time; rosy pink indicates ongoing remodeling.

Types of Wound Closures

  • Primary Wound Closure (Primary Intention):
    • Small, clean-cut wounds immediately closed (tapes, bandages, sutures, staples).
    • Not usually seen by skilled wound care clinicians.
  • Secondary Intention (Secondary Healing):
    • Larger, dirtier wounds needing debridement, not immediately closed.
    • Heals through inflammatory, proliferation, and maturation phases.
    • Typically seen in wound care (physical therapy).
  • Delayed Primary Closure:
    • Wounds cleaned first, then closed by a provider (sutures, staples).
    • Physical therapists may or may not be involved in initial cleaning, but not in the closure itself.