Wound healing
Wound healing
- First intention:
- clean surgical wounds withouth tissue loss that heals with minimal fibrosis
- Second intention:
- wounds left open that heal to fill gap with extensive fibrosis (granulation tissue, contraction, epithelisation)
- Used when no possilibity of tension-free approximation (loss tissue, oedema, infection)
- Third intention:
- delayed primary closure (wounds with high risk of infection if closed early; dog bites, contaminated wounds, delayed presentation)
- best left for exploration, debridement and toilet with antibiotics and closure after 3-10 days
Stages in wound healing
- Events at epidermis
- Clot formation at site
- Epithelial cells migrate from wound edges (under the clot)
- Integrins on keratinocytes bind to fibronectin
- Proliferation of keratinocytes contributes to the ability to cover wound
- Events at dermis
- Infiltration of polymorphs, macrophages to remove debris
- Fibroblast activity to restore tensile strenght
- Revascularisation
- Myofibroblast contraction
Growth factors involved
- Platelet derived growth factor
- Epidermal growth factor
- Transforming growth factor
- Cytokines
- Tumour necrosis factor
Granulation tissue
- Vascular: proliferating capillary buds
- Fibrous: fibroblasts
- Inflammatory cells: Macrophages
Takes part in healing process
Potentially deleterious in joint destruction (rheumatoid arthritis by granulation tissue - Pannus)
Tissue is resistant to infection. Not resistant to trauma, chemical agents, radiation
Factors affecting wound healing
- Patient
- Old
- Obese
- Smoking
- Systemic diseases- diabetes, cardiac disease, immunosuppression, poor nutrition
- Wound
- Hypoxia / ischaemia
- Infection / contamination
- Mobility across wound
- Surgery
- Inadequate debridement
- Excess tension
- Suture necrosis
Dehiscence
Failure of wound to heal in apposition
Partial / total disruption of surgical wound
Signs of Impending wound dehiscence
- Low grade pyrexia
- "Pink fluid" sign
- Abdominal distension
- Abdominal pain
