2.2 Healing Phases, Healing vs Non-Healing, and Biofilm

2.2 Healing Phases, Healing vs Non-Healing, and Biofilm

Quick Answer: A healing full-thickness wound granulates, shrinks, and resurfaces. A non-healing wound is often infected, biofilm-laden, or sealed by epibole. Biofilm needs frequent debridement plus topical antimicrobials; systemic antibiotics do not reliably kill organisms sitting in slime.

Knowledge areas 010306, 010307, and 010308 sit together on purpose. If you cannot tell hemostasis from proliferation, you will misread a dry clot as failure. If you cannot tell healing from non-healing, you will keep the same weekly foam on a rolled-edge ulcer for two months and call it conservative care.

Hemostasis

Immediately after injury, vessels constrict and platelets aggregate. The fibrin clot is a provisional matrix and a reservoir of growth factors (PDGF, TGF-β, EGF, and others). Hemostasis is brief in a clean acute wound. In a patient on anticoagulants, hemostasis is noisy: you plan for bleeding with debridement (section 2.4) rather than assuming the inflammatory cascade will look textbook.

Inflammation

Neutrophils arrive first and phagocytose debris and bacteria. Macrophages follow, cleaning the bed and signaling fibroblasts and endothelial cells to move into proliferation. In an acute wound this phase lasts days, not weeks. Persistent inflammation is not more healing. Chronic wound fluid is often a soup of matrix metalloproteinases (MMPs) that outrun their tissue inhibitors (TIMPs). Excess MMPs chew the extracellular matrix and growth factors you are trying to preserve with dressings. That MMP/TIMP imbalance is a biochemical way of saying the wound is stuck in inflammation.

Clinical inflammation you should respect includes spreading erythema (or color change), induration, new or increasing pain, purulence, and fever. Local contamination without host response is not automatically a reason to start culture-driven intravenous antibiotics. Host response plus stalled healing is.

Proliferation: granulation, angiogenesis, contraction, epithelialization

Four processes run together:

• Granulation — fibroblasts deposit a vascular, collagen-rich matrix. Healthy granulation is beefy red and slightly granular, not pale, dusky, or friable and bloody at a light touch.
• Angiogenesis — new capillaries feed that matrix. Poor perfusion (PAD, nicotine, edema that chokes capillaries) starves this step.
• Contraction — myofibroblasts pull full-thickness edges centripetally. Contraction is useful in a sacral cavity and dangerous over a joint if it predicts contracture.
• Epithelialization — keratinocytes migrate on a moist, level surface. Dry crust, necrotic eschar, and a closed or rolled edge (epibole) stop migration. Islands of epithelium appear only if appendages survive (partial-thickness, section 2.1).

Maturation and remodeling

Collagen is remodeled, cross-linked, and shifted from early type III toward type I. This takes months, not the day the surface looks pink. Classic teaching is that tensile strength returns to about 80% of original—never 100%. A closed abdominal dehiscence site or a filled pressure injury is still a weak scar. Educate against premature heavy lifting, shear, and stripping the new epithelium with aggressive adhesive.

Healing versus non-healing characteristics

A practical rule used in wound programs: failure to progress in about 2–4 weeks (assuming a healable wound with an appropriate plan) should trigger a search for infection, biofilm, ischemia, unrelieved pressure, malnutrition, or the wrong diagnosis. Acute versus chronic is not a calendar tattooed at day 14; it is a failure of orderly phase progression.

Biofilm

Biofilm is a polymicrobial community attached to the wound surface and protected by extracellular polymeric substance (EPS)—the slime. Organisms in biofilm show tolerance to systemic antibiotics that might kill the same species in planktonic (free-floating) blood-stream infection. A swab of the shiny film often grows whatever is on the surface and does not map the community in the EPS, nor does a single culture tell you the biofilm is gone.

CWCN-level management logic:

1. Mechanically disrupt the community with frequent debridement (conservative sharp when competent and indicated; other methods when sharp is not). One clinic visit of scraping is not a biofilm program.
2. Use topical antimicrobials or antimicrobial dressings as an adjunct after disruption, then reassess.
3. Do not treat the swab of slime as the only intervention, and do not assume a 10-day oral antibiotic course will finish a chronic biofilm venous ulcer.
4. Watch for rapid return of a shiny, adherent film within a day of cleansing—that pattern is more biofilm than simple serous scab.

Biofilm and MMP excess travel together: chronic inflammation feeds protease activity, proteases keep the bed from granulating, and the unhealed surface remains a biofilm habitat.

Primary, secondary, and tertiary intention

• Primary intention: edges are approximated (sutures, staples, glue). Minimal granulation; epithelializes as a fine line if perfusion and technique are good.
• Secondary intention: the defect is left open. It must granulate, contract, and epithelialize from the margins. Most chronic ulcers you manage are secondary-intention problems.
• Tertiary intention (delayed primary closure): the wound is left open until contamination or edema is controlled, then closed. Think contaminated surgical wound, not a 6-month venous ulcer you suddenly suture.

Mixing these terms on the exam is a common miss: a dehisced surgical incision healing as an open crater is secondary intention, not primary, even though it started in the operating room.

Scenario

Mr. Kowalski has a left gaiter venous ulcer, 4.2 × 3.1 × 0.3 cm, present 12 weeks. Measurements have not changed in 3 weeks. The edge is rolled and closed. After clinic cleansing, a shiny film is gone; at the next visit the same film is back. Compression has been inconsistent because of pain. You do not document slowly healing and reorder the same hydrocolloid. You name stalled healing with epibole and likely biofilm, plan edge management and serial debridement, add a topical antimicrobial strategy, fix compression and edema, and look for MMP-driven chronic inflammation rather than a new dressing brand as the entire plan. If host signs of spreading infection appear, that is a separate systemic-therapy decision—not a substitute for biofilm disruption.