Which phase of wound healing is characterized by the predominance of type III collagen, and approximately how long does this phase typically last?

Question

Accepted Answer

A. Proliferative phase; 3–21 days. ## Phases of Wound Healing and Collagen Deposition

**Key Point:** Type III collagen is the predominant collagen during the proliferative phase (3–21 days). It is later replaced by type I collagen during remodelling, resulting in a stronger scar.

### Timeline and Collagen Composition by Phase

| Phase | Duration | Collagen Type | Key Events |
|---|---|---|---|
| Haemostatic | < 1 day | Fibrin clot | Platelet aggregation, coagulation cascade |
| Inflammatory | 1–3 days | Minimal collagen | Neutrophil and macrophage infiltration |
| Proliferative | 3–21 days | Type III collagen (predominant) | Fibroblast proliferation, angiogenesis, granulation tissue |
| Remodelling | 3 weeks–2 years | Type I collagen (replaces type III) | Collagen cross-linking, scar maturation, tensile strength increase |

**Mnemonic:** **HAIR** = **H**aemostasis, **A**ngiogenesis/inflammatory, **I**nterstitial (proliferative), **R**emodelling

**High-Yield:** Type III collagen is more soluble and labile than type I; the ratio of type I:type III increases from ~1:3 during proliferation to ~4:1 in mature scar. This shift is essential for scar strength.

**Clinical Pearl:** Premature wound disruption (e.g., suture removal before 7–10 days) occurs because type III collagen provides insufficient tensile strength early in healing.

Answer

B. Haemostatic phase; less than 1 day

Answer

C. Remodelling phase; 3 weeks to 2 years

Answer

D. Inflammatory phase; 1–3 days

Which phase of wound healing is characterized by the predominance of type III collagen, and approximately how long does this phase typically last?

Explanation

Phases of Wound Healing and Collagen Deposition

Timeline and Collagen Composition by Phase

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Phase	Duration	Collagen Type	Key Events
Haemostatic	< 1 day	Fibrin clot	Platelet aggregation, coagulation cascade
Inflammatory	1–3 days	Minimal collagen	Neutrophil and macrophage infiltration
Proliferative	3–21 days	Type III collagen (predominant)	Fibroblast proliferation, angiogenesis, granulation tissue
Remodelling	3 weeks–2 years	Type I collagen (replaces type III)	Collagen cross-linking, scar maturation, tensile strength increase