Skin - Wound healing

Question 1

What are the four phases of wound-healing?

Answer 1

Haemostatic

Inflammatory

Proliferative

Maturation & Remodelling

Question 2

What happens in the first stage of wound-healing, haemostasis?

Answer 2

Within minutes post-injury, platelets (thrombocytes) aggregate at the injury site to form a fibrin clot. This clot acts to control active bleeding (haemostasis). The speed of wound healing can be impacted by many factors, including the bloodstream levels of hormones such as oxytocin.

Question 3

What happens in the second stage of wound-healing, inflammation?

Answer 3

Bacteria & debris are phagocytosed and removed by macrophages & neutrophils, and factors are released that cause the migration and division of cells involved in the proliferative phase.

Question 4

What happens in the third phase of wound-healing, proliferation?

Answer 4

angiogenesis:
new blood vessels are formed by vascular endothelial cells

fibroplasia (collagen deposition) & granulation tissue formation:
fibroblasts grow and form a new, provisional extracellular matrix (ECM) by excreting collagen and fibronectin

epithelialization:
concurrently, epithelial cells proliferate and ‘crawl’ atop the wound bed, providing cover for the new tissue

contraction:
wound made smaller by the action of myofibroblasts, which establish a grip on the wound edges and contract themselves using a mechanism similar to that in smooth muscle cells. When the cells’ roles are close to complete, unneeded cells undergo apoptosis.

Question 5

What happens in the last phase of wound-healing, maturation and remodelling?

Answer 5

Collagen is remodeled and realigned along tension lines and cells that are no longer needed are removed by apoptosis.

Question 6

Explain the difference between primary and secondary intention wound healing.

Answer 6

First intention (primary union) - restoration of tissue continuity occurs directly, without granulation.

• Involves epidermis and dermis without total penetration of dermis; healing by process of epithelialization
• When wound edges are brought together so that they are adjacent to each other (re-approximated)
• Minimizes scarring
• Most surgical wounds heal by primary intention healing
• Wound closure is performed with sutures (stitches), staples, or adhesive tape
• Examples: well-repaired lacerations, well reduced bone fractures, healing after flap surgery

Second intention - wound repair following tissue loss is accomplished by filling of the wound with granulation tissue.

• The wound is allowed to granulate
• Surgeon may pack the wound with a gauze or use a drainage system
• Granulation results in a broader scar
• Healing process can be slow due to presence of drainage from infection
• Wound care must be performed daily to encourage wound debris removal to allow for granulation tissue formation
• Examples: gingivectomy, gingivoplasty, tooth extraction sockets, poorly reduced fractures

Question 7

Propose strategies to improve wound healing.

Answer 7

Keep granulation tissue moist.
Keep up nutrition - vitamins, calcium Oxygen therapy
Maintain constant temperature Keep wound clean.

Question 8

What are Halsted’s Principles of Surgery?

Answer 8

1. Handle tissues gently
2. Control hemorrhage carefully
3. Preserve blood supply
4. Observe strict asepsis
5. Minimize tissue tension
6. Appose tissues accurately
7. Eliminate dead space