Ch. 25 Principles of Plastic and Reconstructive Surgery

Question 1

What arteries supply the skin?

Answer 1

Direct cutaneous arteries

Question 2

What path do the arteries supplying the skin take?

Answer 2

direct cutaneous arteries pass through the fascial septa between muscle bodies

run subdermally, parallel to the skin surface, and are closely associated with the panniculus muscle in areas where this structure is present.

Question 3

Difference between pigs and horses in blood supply to skin

Answer 3

Horses - direct cutaneous
Pigs - perforating musculocutaneous

Question 4

Which wounds should be considered for primary closure

Answer 4

Clean and clean contaminated

Question 5

How is the skin in the distal extremities of horses supplied

Answer 5

no panniculus muscle exists
the direct cutaneous arteries run beneath and parallel to the dermis. smaller vessels branch off these cutaneous arteries and arborize in the dermis, forming three closely interconnecting plexuses—the deep subcutaneous plexus, the middle cutaneous plexus, and the superficial subpapillary plexus—which together supply the dermis and adnexal structures of the skin.

Question 6

What is an important role of the superficial subpapillary plexus

Answer 6

Thermoregulation

Question 7

Which artery has been utilised for skin flaps in horses

Answer 7

Caudal branch of deep circumflex iliac artery

Question 8

What structural components of the skin impart tension and viscoelasticity

Answer 8

collagen, elastic fibers, and ground substance (primarily proteoglycans)

Question 9

What causes skin to retract when incised

Answer 9

Static skin tension - a result of the elastic fibers in the dermis

Question 10

Incisions made at oblique angles to langer lines become

Answer 10

Curvilinear

Question 11

What is skin extensibility

Answer 11

skin’s normal stretching capacity while an anatomic part is at rest and represents the physical property that allows wounds to be sutured closed following removal of skin

Maximal extensibility perpendicular to langerlines

Question 12

What is Mechanical creep

Answer 12

Bio property of skin, allows skin to stretch beyond its normal limits of extensibility under a constant load.

Question 13

When positioning the horse’s body during surgery the affected region should be under

a. Minimal tension
b. Greatest tension
c. Neutral tension

to facilitate the selection of closure techniques that minimize the risk of postoperative dehiscence.

Answer 13

b. Under greatest tension

Question 13

What is biologic creep

Answer 13

skin does not stretch, but instead increases area of coverage by increasing epidermal mitotic activity, upregulation of blood vessels, and increasing dermal cell numbers, resulting in skin development.

This phenomenon is seen with pregnancy, growth of subcutaneous masses, body wall hernias, and, to the advantage of plastic surgeons, with tissue expanders.

Question 13

How does mechanical creep occur

Answer 13

Mechanical creep occurs as the normally convoluted collagen fibers become straight and aligned parallel to the stretching force.
Stress held constant.
Strain increases with time.

Question 14

Stress relaxation occurs when the strain imposed on a piece of skin is kept constant. What mechanism causes the strain decrease over time

Answer 14

Mechanicalcreep

Over time, the amount of strain required to maintain elongation of the skin is decreased as a result of the collagen fiber alignment and lengthening, which occurs with mechanical creep.

Question 15

The collagenolytic and inflammatory processes that take place during early wound healing serve to weaken the suture-holding ability of skin,
Sutures should be placed how far from the skin edge to improve security?

a. 1cm
b. 2cm
c. 0.5cm
d. 1.5cm

Answer 15

c. 0.5cm

Question 16

Which is the most important determinant as to whether or not a wound will dehisce

a. Tissue strength
b. Suture size
c. Number of suture bites
d. Cutting vs taper needle used

Answer 16

a. Tissue strength

Question 17

What distance should be allowed between sutures

a. 0.5cm
b. 1cm
c. As close as necessary to approximate the skin edges
d. Twice the thickness of the skin

Answer 17

c. As close together as is necessary to approximate the skin edges accurately.

In human surgery, placing interrupted sutures 0.5 cm apart provides tissue apposition and minimizes tension on individual sutures.20 The suggestion that the distance between individual sutures should be twice the thickness of the skin may apply, although in some instances, this procedure may result in an excessive number of sutures being used, leading to impaired healing as a result of excessive tissue reaction.

Question 18

More sutures are required in

a. Thicker skin
b. Thinner skin
c. No difference

Answer 18

b. thinner skin

Question 19

For wounds under tension one should

a. increase the suture size
b. the number of suture bites
c. neither

Answer 19

b. the number of suture bites

Question 20

Extrinsic tension is related to

a. Size of defect being closed
b. Suture size
c. Tension in the suture loop

Answer 20

a. Size of the defect being closed

Extrinsic tension results from opposing forces exerted by the surrounding skin on the suture when drawing the skin edges together. Extrinsic tension is related to the size of the defect being sutured and to the amount of redundant or loose skin in the area.

Question 21

Higher intrinsic tension can be caused by

a. Amount of redundant or loose skin
b. Size of defect being closed
c. Postoperative swelling

Answer 21

c. Postoperative swelling

Intrinsic tension is the constricting effect within the suture loop, which, if excessive as a result of the suture being tied too tightly, causes strangulation of the blood supply to tissue within the loop of the suture. A higher degree of intrinsic tension can be generated with heavier suture material, and any postoperative swelling will increase the intrinsic tension of a suture.

Question 22

Continuous patterns have been shown to result in

a. Increased edema
b. Shortened effect on inflammatory phase of wound healing
c. Good cosmetic appearance in reconstructive surgery
d. Greater tensile strength than simple interrupted

Answer 22

a. Increased edema

Continuous patterns have been shown to result in increased edema and compromised circulation and to have a prolonging effect on the inflammatory phase of wound healing.

Question 23

Where is a half-buried mattress suture used a. Closing muscle bellies under tension b. Apex of Y shaped incision c. Eyelid laceration repair d. Thin skin

Answer 23

b. Apex of Y shaped incision Also called a three-point or half-buried mattress suture, the corner suture is used to secure the sharp intersecting point of a Y-shaped incision. The intersecting apex of a Y-incision is predisposed to ischemia, and the design of this suture pattern is such that it will not further compromise the blood flow. The three-point suture can also be used in other situations in which the angle of the skin edge, when sutured, would predispose it to ischemia.

Question 24

Necrosis of skin flaps when closing wounds under tension results primarily from a. Suture tension b. Vascular damage from undermining the tissue

Answer 24

B. vascular damage results primarily from the process of undermining the tissue, skin with a good blood supply can be closed under considerable tension without fear of necrosis.

Question 25

Tension sutures can usually be removed within how long? a. 7-10 days b. 14 days c. 3-5 days d. 21 days

Answer 25

Tension sutures can usually be removed within 7 to 10 days, depending on the residual skin tension and provided that the site can be bandaged for additional suture line support.

Question 26

How far from the wound margin should a mattress suture be placed? a. 0.5cm b. 1-2cm c. 2-4cm d. 0.25cm

Answer 26

c. 2-4cm They are placed 2 to 4 cm away from the wound margin and prior to sutures used to appose the skin edges. The vertical pattern is stronger under tension than the horizontal pattern and, as with a simple interrupted suture, results in little if any compromise to the microcirculation.

Question 27

Which is correct in order of strongest to weakest suture pattern a. Vertical mattress, horizontal mattress, cruciate b. Horizontal mattress, cruciate, vertical mattress c. Vertical mattress, cruciate, horizontal mattress d. Cruciate, vertical mattress, horizontal mattress

Answer 27

a. The vertical pattern is stronger under tension than the horizontal pattern.

Question 28

What are quilled sutures a. Suture made from sterile feather quills b. Using rubber tubing etc to distribute pressure c. Diagonally placed sutures d. Barbed suture

Answer 28

b. Buttons, plastic or rubber tubing, or gauze can be used beneath the skin suture loop to distribute pressure and prevent the suture from cutting through the skin (see Figures 16-11, B and C). These are known as quilled support, quilled, or stented sutures

Question 29

The corium vertical mattress pattern a. Everts the skin b. Inverts the skin c. Perfect apposition

Answer 29

c. Perfect apposition The corium vertical mattress pattern results in minimal trauma. The suture penetrates the skin and exits at the wound level through the corium (dermis). On the opposite side of the skin defect to be closed, the suture is placed entirely in the corium, where it exits intradermally at the skin edges, penetrates the dermis again at the other side of the defect, and exits near the initial penetrating suture, where the knot is tied. This results in a cosmetically superior closure because the sutures exit on only one side of the defect, which ensures perfect alignment of the skin edges without inversion or eversion.

Question 30

Biomechanically, the addition of negative-pressure wound therapy decreases lateral tension forces on sutured incisions by approximately a. It doesn't b. 75% c. 50% d. 25%

Answer 30

c. 50%

Question 31

Despite skin healing, tissue strength is what % of normal tissue at 3 weeks? a. 20% b. 50% c. 75% d. Same as normal tissue

Answer 31

a. 20% at 3 weeks Despite skin healing, tissue strength is only 20% of normal tissue at 3 weeks, 50% at 3 months, and can remain 20% to 30% weaker than the original tissue at 1 year

Question 32

What is the simplest tension relieving procedure

Answer 32

Undermining the skin edges around the wound or excision site prior to closure is the simplest tension-relieving procedure

Question 33

As a rule, in a fresh wound, what distance should be elevated on each side of the wound a. Equal to the width of the defect b. Double the width of the defect c. Half the width of the defect d. To the distance where the suture farthest from the wound edge will be placed

Answer 33

a. distance equal to the width of the defect itself should be elevated on each side of the wound

Question 34

What is the optimal length to width ratio of a fusiform defect a. 3:1 b. 2:1 c. 4:1 d. 1:1

Answer 34

c. 4:1.

Question 35

When making a single release incision the incision should be placed in healthy tissue at what distance away from the wound’s edge? a. 1cm b. Half the width of the wound c. The width of the wound d. 0.5cm

Answer 35

c. Width of the wound away from the wound’s edge

Question 36

In mesh expansion: as a guideline, in fresh wounds, the distance between the individual stab incisions and between the adjacent rows should measure approximately a. 1cm b. 3cm c. width of the wound d. half the width of the wound

Answer 36

a. 1cm As a guideline, in fresh wounds, the distance between the individual stab incisions and between the adjacent rows should measure approximately 1 cm. Placing either the rows or the incisions too closely should be avoided to prevent the possibility of the adjacent stab incisions becoming confluent or causing focal vascular compromise. The appropriate length of the stab incisions varies depending on the degree of elasticity and pliability of the undermined skin. In fresh wounds, more expansion can be obtained with smaller incisions, whereas for those wounds where the surrounding skin is thickened and fibrotic, longer incisions are required to achieve the same result.

Question 37

The V-to-Y-plasty technique for relieving tension requires a V-shaped incision with the point of the V directed towards or away from the defect to be closed?

Answer 37

point of the V directed away from the defect to be closed.

Question 38

In Z plasty: An angle of 60 degrees is most frequently used, which results in what % gain in length? a. 50% b. 75% c. 25% d.100%

Answer 38

b. 75%

Question 39

What is W-plasty used for

Answer 39

improve cosmetic appearance of a scar

Question 40

Tension required to close a wound can be decreased by what % when pre-sutures are placed a. 40% b. 20% c. 75% d 100%

Answer 40

a. 40%

Question 41

External skin stretching devices: Tension applied between the sides should range between? a. 0.5-4kg b. 0.5-1kg c.0.25-0.5kg d. 4-8kg

Answer 41

a. 0.5-4kg Although the greatest gains in skin recruitment are seen between 48 and 72 hours, stretching can be achieved in as short as 20 to 30 minutes in wounds where the skin and subcutaneous tissues are normal. The applied tension between the sides of whatever system is used should range between 0.5 and 4 kg Depending on the system used, tension can be gradually increased until this limit is reached. Tensions greater than this can injure small blood vessels, decreasing perfusion and leading to skin margin necrosis.66

Question 42

The double S-shaped incision with a bi-winged excision, the bow tie, and the combined V incision are alternative methods of modifying what defect?

Answer 42

Circular

Question 43

What is the difference between a pedicle graft and a skin graft

Answer 43

Pedicle graft has its own blood supply intact A skin flap or pedicle graft is a portion (or flap) of skin that, when created, can be moved from its original location to a second location on the body while, by virtue of its attachment (or pedicle), it maintains its vascular supply. The survival of these grafts, unlike that of free skin grafts, is not dependent on successful revascularization from the recipient site. Pedicle grafts, because they have an attached blood supply, can be used to cover areas that, because of an inadequate blood supply, would be unsuitable

Question 44

Difference between random pattern flaps and axial pattern flaps

Answer 44

Random pattern flaps, which do not have a defined vascular pattern, depend on the subdermal plexus for their survival and have been referred to as subdermal plexus flaps. Axial pattern flaps, on the other hand, contain at least one major direct afferent and efferent cutaneous vessel, and are usually named in accordance with that vessel.

Question 45

What is the optimal length to width ratio for a single pedicle flap?

Answer 45

studies show that the optimal ratio for a flap varies with the location on the body. Length-to-width ratios from 1 : 1 to 3 : 1 for single- pedicle and 1.5 : 1 to 3 : 1 for bipedicle flaps have been reported in the veterinary literature.

Question 46

In relation to skin flaps what is the delay phenomenon

Answer 46

The delay phenomenon has been used to enhance the blood supply to the skin by 150% to increase the chances of flap survival. This two-stage technique involves incising and undermining the skin and subcutaneous tissue of the proposed flap and then leaving it sutured in its original location for a period of time - 3 weeks

Question 47

What is an advancement flap and give an example

Answer 47

No rotation of the elevated skin H-Plasty