Primary Wound Closure

Question 1

What are the 3 division of the vascular supply to the skin?

Answer 1

• Superficial/Subpapillary plexus
• Middle/Cutaneous plexus
• Deep/subdermal/subcutaneous plexus

Question 2

What are the main differences regarind the cutaneous angiosomes in dogs and cats?

Answer 2

• Dogs have a greater density of collateral SQ vessels
• Cats have a smaller number and wider distribution of curaneous perforating vessels

These differences apply mainly to the trunk

Question 3

Define the following terms in relation to wound closure:

• Primary wound closure (First intention healing)
• Delayed primary wound closure
• Secondary Closure (Third intention healing)
• Second intention healing

Answer 3

• Primary wound closure = Sutured wounds
• Delayed primary wound closure = suturing 2-5 days after wound initial, before granulation tissue development
• Secondary Closure = Closure of the would after granulation tissue has formed in the wound bed
• Second intention healing = Heals without suturing - usually va contraction and epithelialisation

Question 4

What is the rate of epithelialisation in primary wound healing?

Answer 4

1mm/day.

A perfectly apposed wound can therefore be epitheliased within 24-48hr

Question 5

What is the reported %strength of wounded skin in comparison to normal skin at the following time points:

• 14 days
• 3-4 weeks
• Several months

Answer 5

• 14 days - 5-10% strength
• 3-4 weeks - 25%
• Several months/1 year - 70 - 80% strength

Question 6

How does tension affect wound healing?

Answer 6

Tension can disrupt cutaneous perfusion and retard wound healing

Question 7

List the 5 braod categories which can effect wound healing

Answer 7

• Tension
• Pressure
• Motion
• Self-Mutilation
• Patient Health

Question 8

What patient health factors can significantly retars epithelialisation?

Answer 8

• Uraemia
• Exogenous steroid excess
• Hyperadrenocorticism
  
  • Steroids prolong the inflammatory phase and delay cutaneous wound healing
• Geriatric
  
  • Decreased cutaneous perfusion, increased skin fragility, increases risk of infection
• Malnutrition
  
  • delayed neovascularisation, decreased collagen synthesis, prolongation of inflammation, decreased leucocyte phagocytosis, B- and T-cell dysfunction, decreased mechanical skin strength
  • Methionine, cysteine and arginine all important
  • FAs (within cell membranes, vital for cell function)
  • VitC (collagen synthesis, cell mitosis and monocyte migration)
    
    • Zinc and iron (enzymatic reactions in production of DNA and RNA and proteins including collagen)

Question 9

What are the reported benefits of using a scalpel for a skin incision over electrocautery/CO2 laser/radiowaves?

Answer 9

• Scalpel incision have approximately twice the wound strength at 10-12 days post-op compared to electrocautery
• Produce less drainage with faster and stronger healing
• Skin incised with radiowave, CO2 laser and monopolar, char will penetrate the skin laterally 0.172, 0.215 or 0.255mm respectively

In humans, studies have concluded that incision made with electrocautery were faster and resulted in less post-op pain with no difference in scar formation of post-op infection

Question 10

What is meant by the ‘golden period’ for wound management?

Answer 10

The golden period is a period of 3-6hr during which the bacteria within a minimally contaminated wound can multiply to 10⁵ per gram of tissue or per ml of exudate, at which point the risk of infection increased dramatically

Question 11

List some differences between dogs and cats in regards to wound healing

Answer 11

• Cats have lower cutaneous perfusion for the first week (by 2 weeks, no difference)
• Cats have a significantly lower wound breaking strength 1 week post-op
• Open wounds in cat heal largely by contraction whereas dogs heal largely by central “pull” of fibroblasts and epithelialisation

Question 12

Defects should generally be created and closed parallel to tension lines except for…

Answer 12

On distal limbs

Question 13

How long may it take for the degree of trauma to be fully established after a crushing injury?

Answer 13

3-7 days

Question 14

What is a chain stitch knot?

What are its advantages?

Answer 14

An aberdeen knot!

Greater relative knot security and less volume

Question 15

What is the recommended suture tag length of buried knots?

Answer 15

3-5 mm

Question 16

What is the recommended suture tag length of buried knots?

Answer 16

3-5 mm

Question 17

Which suture materials require 3-6 square knots for security (as apposed to 4-6)?

Answer 17

• Polyglactin 910
• Polyglytone (Caprosyn)
• Nylon
• Prolene

For size 3-0

Question 18

How many throws are required when tying to a loop at the end of a continuous pattern?

Answer 18

At least 5

Question 19

List 2 options of continuous pattern closure of the SQ

Answer 19

• Simple continuous (bits perpendicular to incision)
• Running horizontal mattress (Bites parallel to incision)

Question 20

What is recommended for ideal dermal apposition with a continuous horizontal intradermal pattern?

Answer 20

• Length of each bite no more than 0.5cm
• Alternating bites should be backtracked 1-2mm

Question 21

List some advantages of the continuous vertical intradermal pattern

Answer 21

• Vascular supply to the wound edges is unlikely to be compromised as the suture material within the wound runs parallel to the cutaneous perforating vessels
• Surgery time may be decreased

Question 22

List some techniques for correcting dog ears

Answer 22

Question 23

List two sepcialised methods for correcting dog ears in wounds which are 2cm or smaller

Answer 23

• Apex cutaneous suture
• Horizontal oblique dermal suture

Question 24

List some methods of prevention/correction of dog ear formation in ellipital incisions

Answer 24

• A - Fudging - placing sutures further apart on longer side when discrepancy is small
• B - Rule of halves
• C - Sutures from ends to center with dog ear removal
• D - Suturing from one end to the other with dog ear removal
• E - Suturing from centre to ends with dog ear removal
• F - Lengthening the short side with half of a fusiform

Question 25

How may NSAIDs theoretically inhibit wound healing?

Answer 25

COX-2 production occurs at wound edges leading to infiltration of inflammatory cells and fibroblast proliferation within the first week * NSAIDs could theoretically inhibit this process via inhibition of COX-2

Question 26

What are the purported effects of therapeutic lasers?

Answer 26

* Enhanced leucocyte infiltration * Increasing growth factors * Increasing macrophage activity * Increasing neovascularisation * Increasing fibroblast and keratinocyte proliferation * Promoting early epithelialisation