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

Explanation

## 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