Axial and myocutaneous flaps

Question 1

What distinguished an axial pattern flap from a subdermal plexus flap?

Answer 1

An axial pattern flap incorporates a direct cutaneous artery and vein, terminal branches of which supply blood flow and drainage for the subdermal plexus. This results in improved survival and ability to create a larger flap

Question 2

How far can an axial pattern flap be safely rotated around its base?

Answer 2

180 degrees

Question 3

What is the difference between peninsula and island axial pattern flaps?

Answer 3

Peninsula flaps maintain intact skin at their base, island flaps are incised around all of their edges.

Question 4

What are the potential advantages and disadvantages of island and peninsula axial pattern flaps?

Answer 4

Peninsula: better protection of vasculature, may be less cosmetic (dog ears from rotation).

Island: more cosmetic but vascular pedicle is more exposed and may be damaged

Question 5

Can axial pattern flaps be applied directly over bone, tendons and ligaments?

Answer 5

Yes

Question 6

What is the overall survival rate of axial pattern flaps?

Answer 6

87-100%

Question 7

What are important species differences between cats and dogs when it comes to axial pattern flaps?

Answer 7

Similar location of direct cutaneous vessels, but cats have a lower density of tertiary and higher order vessels. This translates to less cutaneous perfusion in cats.

Question 8

Which is the easiest direct cutaneous artery to identify in an axial pattern flap?

Answer 8

Caudal superficial epigastric

Question 9

Which is the hardest direct cutaneous artery to identify in an axial pattern flap?

Answer 9

Superficial cervical (omocervical flap)

Question 10

Describe the boundaries of various axial pattern flaps

Answer 10

See table page 1459 Tobias

Question 11

Does the omocervical or thoracodorsal axial pattern flap have a more robust blood supply?

Answer 11

The thoracodorsal

Question 12

How frequently is tip necrosis observed when using thoracodorsal axial pattern flaps?

Answer 12

In up to 70% of dogs when used to repair forelimb defects

Question 13

Why are thoracodorsal axial pattern flaps particularly useful in cats?

Answer 13

Cats have excellent skin mobility and small leg to trunk ratio allowing the thoracodorsal axial pattern flap to reach the carpus

Question 14

Is the dorsal or ventral branch of the deep circumflex iliac artery longer?

Answer 14

The ventral branch

Question 15

What muscle is included in the caudal superficial epigastric axial pattern flap?

Answer 15

The supramammarius muscle

Question 16

What is the clinical survival of caudal superficial epigastric flaps in dogs?

Answer 16

90%

Question 17

The caudal superficial epigastric is a branch of which artery?

Answer 17

The external pudendal

Question 18

Which mammary glands can the cranial superficial epigastric axial pattern flap include?

Answer 18

Glands 3, 4 and 5 (should be stopped just cranial to the prepuce in male dogs)

Question 19

Is the cranial or caudal superficial epigastric flap more robust?

Answer 19

The caudal. It has a longer vascular supply and the anatomic landmarks are less variable.

Question 20

The angularis oris artery is a branch of which artery?

Answer 20

Facial artery

Question 21

What thin muscle superficial to the temporalis muscle is elevated in a superficial temporal axial pattern flap?

Answer 21

Frontalis muscle

Question 22

Extension of a superficial temporal axial pattern flap to what level decreases survival?

Answer 22

Extension to the contralateral zygomatic arch (not recommended). Extension to the contralateral dorsal orbital rim has good survival (93-99%)

Question 23

Which vessel does the caudal auricular axial pattern flap rely on?

Answer 23

The cleidomastoideus branches of the caudal auricular artery and vein

Question 24

How do the landmarks for the caudal auricular axial pattern flap differ in the dog and cat?

Answer 24

The dorsal flap is positioned slightly more midline in the cat

Question 25

What vessel is the superficial brachial artery a branch of?

Answer 25

Brachial artery

Question 26

Is the superficial brachial artery flap considered robust?

Answer 26

No - consider using other flaps if possible. May reach the carpus but usually not robust enough to extend to this level

Question 27

What vessel does the genicular artery originate from?

Answer 27

The saphenous artery

Question 28

What defects are reverse saphenous conduit flaps most useful for?

Answer 28

Wounds on the distal aspect of the pelvic limb

Question 29

What vessels do the reverse saphenous conduit flaps rely on?

Answer 29

Relies on reverse flow through vascular anastomoses between branches of the cranial tibial and saphenous arteries and between tributaries of the medial and lateral saphenous veins

Question 30

What is the distal extent of the reverse saphenous conduit flap?

Answer 30

The anastomoses between the medial and lateral saphenous veins at the level of the hock

Question 31

What is a common clinical occurrence following placement of a reverse saphenous conduit flap?

Answer 31

Vascular congestion due to reverse venous flow. To maximize the chances of flap survival it is recommended to perform angiographic studies prior to flap dissection to ensure both the cranial and caudal saphenous branches are present (loss of one branch reduces chance of survival)

Question 32

The lateral caudal arteries and veins are branches of which vessels?

Answer 32

The caudal gluteal arteries and veins

Question 33

At what level is the tail amputated following creation of a dorsal or ventral lateral caudal axial pattern flap?

Answer 33

Between coccygeal vertebrae 2 and 3

Question 34

What is the vascular pattern to the latissimus dorsi muscle?

Answer 34

Type V (single dominant vascular pedicle and a segmental vascular pedicle). So long as the dominant vascular pedicle survives the muscle will survive.

Question 35

What is the dominant vascular pedicle of the latissimus dorsi muscle?

Answer 35

The thoracodorsal artery

Question 36

What are the most common causes of axial pattern flap necrosis?

Answer 36

Typically caused by inadequate blood perfusion. This can be impacted by hematoma formation, excessive tension, inappropriate handling of the flap or incorrect landmarks, rotation beyond 180 degrees.

Question 37

What is the typical appearance of a flap at 6 days depending on whether the arterial or venous supply is primarily affected?

Answer 37

Venous: congested, cyanotic
Arterial: pale