Regarding the phases of wound healing, all of the following statements are correct EXCEPT:

Question

Accepted Answer

B. The remodeling phase begins at week 2 and involves complete replacement of type III collagen with type I collagen within 2 weeks. ## Phases of Wound Healing — Timeline and Cellular Events

### Overview
Wound healing progresses through four overlapping phases: hemostasis, inflammation, proliferation, and remodeling. Each phase has distinct cellular and molecular hallmarks.

### Phase-by-Phase Breakdown

| Phase | Timeline | Key Events | Dominant Cells |
|-------|----------|-----------|----------------|
| **Hemostasis** | 0–minutes | Platelet plug, fibrin clot formation, vasoconstriction | Platelets, endothelium |
| **Inflammation** | 0–hours to 3–5 days | Neutrophil infiltration (0–48 h), macrophage predominance (48 h–3 d), cytokine release | Neutrophils → Macrophages |
| **Proliferation** | Day 3–5 to week 3 | Angiogenesis, fibroblast migration, collagen (type III) deposition, epithelialization, granulation tissue | Fibroblasts, endothelial cells, myofibroblasts |
| **Remodeling** | Week 3 onwards | Type III → Type I collagen cross-linking, scar maturation, tensile strength increase | Fibroblasts (apoptosis), myofibroblasts |

**Key Point:** The remodeling phase is **prolonged** — it begins around week 3 and continues for **months to years**. Type III collagen is NOT completely replaced by type I collagen within 2 weeks; this process takes weeks to months. The wound achieves only ~70–80% of original tensile strength even after 1 year.

### Why Option 3 Is Incorrect

**High-Yield:** Remodeling does NOT occur in 2 weeks. The timeline is:
- Week 3: Remodeling begins (type III collagen starts being replaced)
- Weeks 3–12: Active collagen remodeling and cross-linking
- Months to years: Continued maturation and scar refinement

The statement "complete replacement of type III collagen with type I collagen within 2 weeks" is **false** — this is a common exam trap. Remodeling is the longest phase.

### Clinical Pearl

**Warning:** Do not confuse the **onset** of remodeling (week 3) with its **completion**. A wound's tensile strength at 2 weeks is still only ~30% of normal; it reaches ~80% at 3 months and plateaus there. This is why:
- Sutures are removed at 7–10 days (epithelialization is complete)
- But the scar continues to remodel for months
- Keloids and hypertrophic scars result from excessive remodeling

Answer

A. The inflammatory phase peaks at 48–72 hours and is characterized by neutrophil infiltration followed by macrophage predominance

Answer

C. Hemostasis occurs within seconds to minutes and involves platelet aggregation and fibrin deposition

Answer

D. The proliferative phase begins at day 3–5 and includes angiogenesis, collagen deposition, and epithelialization

Regarding the phases of wound healing, all of the following statements are correct EXCEPT:

Explanation

Phases of Wound Healing — Timeline and Cellular Events

Overview

Phase-by-Phase Breakdown

Why Option 3 Is Incorrect

Clinical Pearl

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Phase	Timeline	Key Events	Dominant Cells
Hemostasis	0–minutes	Platelet plug, fibrin clot formation, vasoconstriction	Platelets, endothelium
Inflammation	0–hours to 3–5 days	Neutrophil infiltration (0–48 h), macrophage predominance (48 h–3 d), cytokine release	Neutrophils → Macrophages
Proliferation	Day 3–5 to week 3	Angiogenesis, fibroblast migration, collagen (type III) deposition, epithelialization, granulation tissue	Fibroblasts, endothelial cells, myofibroblasts
Remodeling	Week 3 onwards	Type III → Type I collagen cross-linking, scar maturation, tensile strength increase	Fibroblasts (apoptosis), myofibroblasts