While normal wound healing involves a coordinated process of hemostasis, inflammation, proliferation, and remodeling, several factors can disrupt these stages — leading to aberrant healing. These abnormalities may cause delayed healing or excessive scar formation.
Delayed Wound Healing
Common Causes: Delayed wound healing occurs when normal repair mechanisms are impaired.
| Cause | Mechanism / Example |
|---|---|
| Infection | Persistent inflammation delays tissue repair. |
| Foreign bodies | Prevent proper closure and granulation. |
| Ischemia | Poor blood flow limits oxygen and nutrient delivery. |
| Diabetes mellitus | Impaired leukocyte function and microangiopathy slow repair. |
| Malnutrition | Protein, vitamin C, and zinc deficiency affect collagen synthesis. |
| Scurvy (Vitamin C deficiency) | Inadequate hydroxylation of proline and lysine → defective collagen cross-linking. |
Key Point 🧠:
Anything that interferes with oxygen supply, nutrient availability, or infection control can significantly delay wound closure.
Hypertrophic Scars
| Feature | Description |
|---|---|
| Definition | Excessive formation of granulation tissue and collagen, limited to the original wound area. |
| Common Sites | Burn injuries and surgical incisions. |
| Collagen Type | Mainly Type III collagen. |
| Outcome | Raised scar that may regress with time. |
Key Point 🧠:
Hypertrophic scars stay within the wound borders and may improve spontaneously.
Keloid Formation
| Feature | Description |
|---|---|
| Definition | Exuberant, tumor-like overgrowth of scar tissue beyond the boundaries of the original wound. |
| Genetic Predisposition | Common in African American populations. |
| Common Sites | Earlobes, face, neck, sternum, shoulders, and forearms. |
| Collagen Type | Predominantly Type III collagen (disorganized). |
| Course | May recur after surgical removal. |
Key Point 🧠:
Unlike hypertrophic scars, keloids extend beyond the original wound and rarely regress.
🎯 Learning Objective
By the end of this topic, medical students should be able to:
- Identify and differentiate between types of aberrations in wound healing — including their causes, morphologic features, and associated collagen types.
