Local or subdermal plexus flaps

Question 1

What vascular supply do subdermal plexus flaps rely on for survival?

Answer 1

Collateral circulation from the remaining cutaneous attachment and the subdermal plexus.

Question 2

What are the most critical issues to ensure flap preservation?

Answer 2

Preservation of blood supply, closure with minimal tension, appropriate nutritional status

Question 3

What is the delay phenomenon?

Answer 3

A group of mechanisms by which flap survival is enhanced through staged flap development.

Question 4

What are the major factors that contribute to the delay phenomenon?

Answer 4

Alterations in sympathetic tone (depletion of norepinephrine), dilation of choke vessels, reorientation of vessels (parallel to the long axis of the flap), early and late changes in tissue metabolism (increased production of prostaglandin E2 that causes vasodilation), and neovascularization (increase in vasculogenesis by day 21).

Question 5

How much does perfusion decrease following elevation of a single or bipedicle flap?

Answer 5

10 and 40% respectively. This increases back to 120-150% of normal by 3 weeks if the flap is delayed. With subsequent elevation of the delayed flap the perfusion only decreases to 90% of normal.

Question 6

Should a subdermal plexus flap ideally have a wider apex or base?

Answer 6

Base should be wider to preserve vascular supply

Question 7

What are the different types of advancement flaps?

Answer 7

Single pedicle (two single pedicle flaps may be used to create an H-plasty) and bipedicle (same as a simple relaxing incision)

Question 8

What is the main disadvantage of an advancement flap?

Answer 8

Elastic recoil and innate tension is transmitted to the wound edge

Question 9

What are the three types of rotational flaps?

Answer 9

Rotation flap: covers a defect along a common border.

Transposition flap: share a common border but the flap is rotated across intact skin.

Interpolation flap: do not share a common border. Must be tubed or incorporated into a bridging incision.

See images on page 1450 Tobias.

Question 10

What is the effect of increasing angle between a transposition flap and wound?

Answer 10

Greater angles reduce tension on the closure of the donor and primary site (as the donor site becomes orientated 90 degrees to the lines of tension). However increased angles and longer flaps will also lead to bigger dog ears. Normally the flap is developed within 90 degrees of the defect.

Question 11

What is the benefit of an H-plasty compared to a single pedicle advancement flap?

Answer 11

It has a wider base to length ratio, improving blood supply

Question 12

What is an example of a commonly used interpolation flap?

Answer 12

Lip-to-lid flap

Question 13

What are the two classifications of distant flaps?

Answer 13

Direct: skin is transferred directly by bringing the recipient skin into direct proximity with the donor skin (pouch or hinged flap).

Indirect: skin is tubed and walked toward the skin defect by progressive division of its pedicles (rare)

Question 14

What is a composite flap?

Answer 14

A flap that incorporates underlying structures with the skin (e.g. myocutaneous flaps [latissimus dorsi] or mucocutaneous subdermal plexus flaps [lip-to-lid])

Question 15

How many of the four attachments of the elbow and flank folds have to be maintained to ensure flap viability?

Answer 15

Only one

Question 16

Which arteries supply the subdermal plexus in upper and lower labial flaps?

Answer 16

The superior and inferior labial arteries (these rich vascular plexi allow for mobilization of full-thickness composite flaps)

Question 16

Which artery is likely responsible for the excellent survival of the lip-to-lid flap?

Answer 16

The angularis oris artery

Question 17

How wide should the base of a lip-to-lid flap be in relation to its length?

Answer 17

Width should be at least 50% of the length

Question 18

What are some examples of commonly used subdermal plexus flaps?

Answer 18

Elbow and flank fold, scrotal, perivulvar, phalangeal fillet, labial flaps, lip-to-lid

Question 19

What are examples of direct distant subdermal plexus flaps?

Answer 19

Hinge (single pedicle) and pouch flaps (double pedicle)

Question 20

When performing a ‘walking’ tubed pedicle flap how many days after creation can the initial pedicle base be severed?

Answer 20

Should be half severed at 18 days, then completely severed at 21 days to allow rotation into the wound bed. Remaining pedicle can be severed at 3-4 weeks.

Question 21

What are some common complications associated with subdermal plexus flaps?

Answer 21

Infection, seroma, skin edge dehiscence, and necrosis.