Ch 79 Axial pattern and Myocutnaeous flaps

Question 1

Axial Pattern flaps

Answer 1

• incorporate a direct cutaneous artery and vein, terminal branches of which supply blood flow and drainage for the subdermal plexus
• Compared with random or subdermal plexus flaps incorporation of direct cutaneous vessels allows for a larger flap with more consistent survival

Question 2

What are the two braod options when elevating an axial pattern flap?

Answer 2

• Penisular flap - Intact skin at its base
• Island flap - Skin incised along all edges and flap is rotated around vascular base

Question 3

What is a composite flap?

Answer 3

An axial pattern flap composed of skin as well as muscle, bone or cartilage

Question 4

What is the reported overall survival rate of axial pattern flaps?

Answer 4

87 - 100%

Question 5

Advantages

Answer 5

• ability to close a large defect without tension
• early closure without extended open wound management
• coverage of areas with less than optimal wound healing conditions
• excellent flap survival rates.
• Many of these flaps are easy to develop and rotate, and no specialized equipment is required.
• Unlike mesh grafts > can be placed directly over bone, tendons, or ligaments.
• Although the tips of the flaps are prone to necrosis, mean survival of axial pattern flaps is at least 50% greater than for subdermal plexus flaps

Question 6

disadvantages

Answer 6

• Axial pattern flaps limited for use on distal limb.
• regional variability in vascular anatomy > ultrasonography and color-flow Doppler can facilitate identification of artery
• Ease varies with each type of flap, may contribute to higher failure rates in overweight patients.

Question 7

List some differences between cats and dogs in regard to skin anatomy and wound healing

Answer 7

• Dogs have a much higher density of tertiary and higher order vessels than cats (less cutaneous perfusion to the uninjured skin of cats)
• At 7 days after wounding, wound strength with first intention healing in cats is half that of dogs
• Granulation tissues takes 2x as long to form in cats and begins at the periphery
• Removal of SQ reduces the rate of epithelialisation, especially in cats (recommended to preserve SQ with harvesting axial pattern flaps in cats)

Question 8

General Considerations for Reconstructive Flaps

Answer 8

Flap size
- pre-op paper can be cut to the estimated donar flap site
- sterile marker and a ruler
- - The recipient bed is prepared first

Recipient Bed
- The presence of granulation tissue is not required for axial pattern flaps; however, the recipient bed should be free of gross contamination.
- With chronic wounds, several millimeters of skin bordering the recipient site are removed

Flap Development
- follow guidelines
- imperative to maintain blood supply. Excessive twisting of island flaps can directly obstruct arteries and veins
- transillumination or colourflow doppler

Surgical Closure
- minimizing dead space with tacking sutures along the borders
- Before definitive closure > interrupted skin sutures are placed
- Interrupted patterns provide gaps for drainage, prevent extensive loss of wound closure in the event of flap tip necrosis, and permit more precise apposition. Staples reduce surgical time

Drains
- Drains reduce dead space > prevent subcutaneous fluid build-up under the flap, which can lead to surgical failure
- not directly under flap

Postoperative Care
- A multimodal approach (e.g., a nonsteroidal antiinflammatory drug and an injectable opioid) is recommended
- Cool packs for the first 36 to 72 hours, and then warm packs should be used for 3 to 5 days
- bandages: protect, reduce dead space vs excessive compression could lead to hypoxia

Question 9

Name the following axial pattern flaps

Answer 9

1 = Caudal auricular
2 = Omocervical
3 = Thoracodorsal
4 = Caudal superficial epigastric
5 = Lateral genicular
6 = Deep circumflex iliac
7 = Lateral caudal
8 = Superficial brachial

Question 10

Describe the Thoracodorsal axial pattern flap
what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 10

• Based on cutaneous branch of thoracodorsal artery and vein
• Cranial incision from acromion dorsally along scapular spine
• Caudal incision parallel and equidistant from caudal shoulder depression
• Can extend to contralateral scapulohumeral joint
• Elevated under cutaneous trunci muscle
  Potential uses: Thoracic, forelimb, shoulder, axillary defects

Question 11

thoracodorsal success

Answer 11

• Experimentally, the area of survival reported to be 98%; however, these flaps were not rotated from their wound beds.
• Clinically, results in dogs are not as successful. Partial tip necrosis is reported in up to 70%
• In cats the area of survival was 98%.

Question 12

Describe the Omocervical axila pattern flap
what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 12

• Based on superficial cervical branch of the omocervical artery and vein (originates at level of prescap LN and courses cranially)
• Caudal incision from acromion dorsally along scapular spine
• Cranial incision parallel and equidistant from cranial edge of scapula
• Can extend to contralateral scapulohumeral joint
  Potential uses: Face, ear, cervical, shoulder, axillary defects

Question 13

omocervical success

Answer 13

• Blood supply less robust than that of the thoracodorsal artery
• supplies a smaller area.
• Additionally, landmarks are less consistent and appear harder to find

Question 14

Describe the dorsal deep circumflex iliac axial pattern flap
what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 14

• Based on deep circumflex iliac artery and vein which exit lateral abdominal wall cranioventral to wing of ilium and divides into dorsal and ventral branch
• Base of flap at ventral extent of cranial edge of ilium
• Caudal incision midway between wing of ilium and greater trochanter extending dorsally
• Cranial incision parallel and equidistant from wing of ilium
• Can be extended to contralateral paralumbar or flank fold
• Elevated below cutaneous trunci muscle
  Potential uses: ipsilateral flank, lateral lumbar, pelvic lateromedial thigh, greater trochnater defects

Question 15

Describe the ventral deep circumflex axial pattern flap
what vessel is it base on, anatomical landmarks, maximum length, potential uses

flank fold flap based on this atery

Answer 15

• Based on the ventral branch, exiting at same point as dorsal branch but extending down lateral flank and craniolateral thigh
• Landmarks for base and width identical to dorsal
• Caudal incison runs ventrally in a line parallel to cranial border of femoral shaft
• Cranial incision parallel
• Can extend to proximal edge of patella
  Potential uses: Lateral abdominal wall, pelvic, sacral

Question 16

Describe the caudal superficial epigastric axial pattern flap
what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 16

• External pudendal artery and vein exit caudal inguinal canal, provide ventral brance to labia/scrotum and arches cranially to form caudal superficial epigastric
• Ventral midline incision
• Parallel incision laterally and equidistant to teats
• Can extend cranially to include 2nd mammary gland
• Elevated below supramammarius muscle
  Potential uses: Caudal abdominal, flank, inguinal, preputial, perineal, thigh, stifle defects

Question 17

caudal epigastric outcome

Answer 17

• Complications: seroma, bruising, flap edema, drainage, incisional dehiscence (30%)
• Experimentally, survival of 95% of flap area was documented in dogs
• Clinically, 90% of dogs have complete flap survival.
• Most complications are amenable to bandage care or other conservative treatment.

Question 18

Describe the cranial superficial epigastric axial pattern flap
what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 18

• Based on short cutaneous braches of cranial superficial epigastric. Artery exits through rectus abdominis caudoventral to thoracic cage and 2-4cm lateral to midline
• Ventral midline incision from just caudal to thoracic cage extending caudally
• Lateral parallel incision equidistant from 3rd teat
• Can extend to include mammary 3, 4 and sometimes 5
• Elevated below panniculus muscle
  Potential uses: Sternal defects

flaps are shorter and may have a higher complication rate vs caudal epi

Question 19

Describe the angularis oris axial pattern flap
what vessel is it base on, anatomical landmarks, maximum length, potential uses

palpated transorally within the cheek caudal to commissure of lip

Answer 19

• Based on angularis oris artery ( branch of the facial artery) with branches of inferior and superior labial arteries
• Based at labial commisure
• Dorsal incision parallel to ventral zygomatic arch to level of vertical ear canal
• Ventral incision parallel with ventral aspect of mandibular ramus
• Can extend to wing of atlas but more commonly to vertical ear canal
• Can also be created as a noncutaneous rectangular island flap based on the buccal mucosa

Potential uses: Palatal, facial, nasal defects

Question 20

What important underlying structures may be encountered when elevating the angularis oris axial parrern flap?

Answer 20

• Facial nerve (dorsal, ventral and auriculopalpebral branches)
• Auriculotemporal nerve
• Parotid salivary duct
• facial vein

Question 21

angularis oris outcome

Answer 21

• Animals that undergo concurrent maxillectomy will have billowing of the myocutaneous flap during exhalation because of communication of the nasal cavity with the underlying surface of the flap.
• Recently the angularis oris axial pattern flap was described as a means for repairing large facial defects in eight dogs. In that series, all flaps healed with acceptable functional and cosmetic outcomes and without major complications.

Question 22

Describe the superficial temporal axial pattern flap
what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 22

• Based on superficial temporal artery
• Based on caudal aspect of zygomatic arch caudally and lateral aspect of orbital rim cranially
• Extends dorsally to maximal length at dorsal aspect of contralateral orbital rim
• Thin frontalis muscle elevated with flap

Potential uses: Maxillofacial, eyelid defects

Question 23

superficial temporal outcome

Answer 23

• 100% flap survival occurred in 17 of 19 flaps (89.4%). Postoperative complications occurred in eight of 19 flaps (42.1%
• Extending the flap to the level of the contralateral zygomatic arch is therefore not recommended

Question 24

What nerve may need to be transected during elevation of superficial temporal axial pattern flap?

Answer 24

Rostral auricular nerve - does not effect eyelid function

Question 25

Describe the caudal auricular axial pattern flap what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 25

* Based on sternocleidomastoideus branches of caudal auricular artery and vein * Based at palpable depression between vertical ear canal and wing of atlas * Flap is centered over wing of atlas with dorsal and ventral incisions running caudally and parallel to each other * Maxiumu length to spine of scapula * Platysma muscle is elevated with the flap * In cats, the dorsal incision is closer to dorsal midline *Potential uses: neck, facial, ear, dorsal head defects*

Question 26

caudal auricular outcome

Answer 26

- reported better healing in cats - Revision surgery was performed in eight of 16 (50%) dogs and three of 12 (25%) cats | proot 2019

Question 27

Describe the superficial brachial axial pattern flap what vessel is it base one, anatomical landmarks, maximum length, potential uses

Answer 27

* Based on superfical brachial branch of brachial artery * Base centered over proximal 1/3 of flexor surface of elbow * Lateral and medial incision lateral to each other and to the shaft of the humerus * Maximum length distal to greater tubercle * Fragile and easily fails, use as a last resort option *Potential uses: Antebrachial, elbow defects*

Question 28

Describe the genicular axial pattern flap what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 28

* Based on the genicular braches of the saphenous artery and saphenous vein * Genicular artery extends cranially over the medial aspect of the stifle and terminated over its craniolateral surface * Base of flap located 1cm proximal to patella and 1.5cm distal to tibial tuberosity * Incisions extend proximally, parallel to femoral shaft, converging to make base 2cm wider than tip * Maximum length distal to greater trochanter *Potential uses: medial stifle or tibial defects*

Question 29

genicular outcome

Answer 29

- Average flap survival was 99.1% with two dogs developing distal flap necrosis. Minor complications occurred in eight dogs (36%). More robust than previously reported | emersen 2019

Question 30

What is the reverse saphenous conduit flap dependant on?

Answer 30

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 31

reverse saphenous conduit details

Answer 31

- incision is made across the central third of the medial thigh at or slightly above the level of the patella. - The underlying saphenous artery, medial saphenous vein are double ligated and divided. - The cranial incision is started 0.5 to 1.0 cm cranial to the cranial branches of the saphenous artery and medial saphenous vein. - The caudal incision is started a similar distance caudal - undermined below the saphenous vasculature, with a portion of the medial gastrocnemius muscle fascia included to prevent damage to the vessels

Question 32

reverse saphenous ooutcome

Answer 32

- Results of clinical outcome for the reverse saphenous conduit flap are limited. - In one experimental study, flap survival rate was 100% - In another experimental study, damage to the cranial or caudal vascular branch resulted in partial flap failure in 50% and 33%, respectively, and complete failure in 17% and 33%, respectively - Because of the reverse flow of blood through the veins, venous congestion of this flap may occur after surgery

Question 33

Describe the lateral caudal axial pattern flap what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 33

* Based on the left and right lateral caudal arteries and veins (branches of caudal gluteal) * Cranial border of flap is horizontal line where tail attaches to body * Dorsal or ventral midline incision * Elevated deep to dorsal fascia (tricky) * Tail amputated between caudal vertebrae 2-3 * Can be splint along dorsal midline to form 2 flaps *perineum and caudodorsal pelvic region*

Question 34

Describe the latissimus dorsi myocutaneous flap what vessel is it base on, anatomical landmarks, maximum length, potential uses

Answer 34

* Based on thoracodorsal artery * Direct cutanous artery through craniodorsal portion of latissiumus to the skin just dorsal to the scapula * Craniodorsal aspect is level with acromion and caudal to triceps m. Incised in a caudodorsal direction to head of 13th rib * Ventral border starts at thoracic limb skin fold at a point level with lower third of the humerus. Extends parallel to 13th rib * Dissection deep to latissimus dorsi Potential uses: Defects which require more bulky reconstruction such as thoracic wall

Question 35

latissimus dorsi outcome

Answer 35

- one-stage thoracic wall reconstruction after rib chondrosarcoma resection, paradoxical respiratory movement of the flap was noted in dogs. - Complications included superficial skin necrosis distally and minor wound dehiscence.

Question 36

Prognosis of APF

Answer 36

- Postoperative complications occurred in 64 patients (89%) and 8 patients (11%) had no complications. - Complications were: dehiscence, swelling of the flap, necrosis, infection, discharge and seroma. - Flap outcome was excellent in 16 patients (23%), good in 29 (41%), fair in 21 (30%) and poor in 5 (7%). *high complication rate associated with axial pattern flaps but these are usually easily managed and long term outcome is excellent, in either species.* Field 2015

Question 37

What type of vascular pattern does the latissimus dorsi have? What does this mean?

Answer 37

Type V vascular pattern Has a single dominant vascular pedicle and a segmental vascular pedicle Portions of a muscle with this vascular pattern will survive if the transfer is based on the dominant vascular pedicle (thoracodorsal artery for latissimus dorsi)

Question 38

- type I: 1 vascular pedicle - rectus femoris - type II: dominant pedicle and minor vascular pedicle(s) - entire muscle will survive based on dominant pedicle - superficial gluteal, middle gluteal, deep gluteal, rectus femoris, sartorius (cranial) gracilis, semimembranosus - type III: 2 dominant pedicles - division of either pedicle may → necrosis - biceps femoris, semitendinosis - type IV: segmental vascular pedicles - division of more than 2-3 pedicles → distal muscle necrosis - vastus lateralis, intermedius and medialis, sartorius (caudal), gastrocnemis, cranial tibial, superficial digital flexor - type V: dominant pedicle and opposing segmental pedicles - muscle survives based on either system - suitable for transfer: cranial head of sartoris, gracillis, semitendinosus, rectus femoris

Question 39

Cause of Flap Necrosis | inadequate blood perfusion

Answer 39

- Flap elevation results in a significant decrease in circulation to the most distant region of the flap. - exacerbated by poor surgical technique, excessive undermining, and previous tissue trauma. - flap rotation > 180 degrees - Beyond anatomic guidelines - Individual variations - Wound tension > vascular compromise secondary to increased interstitial pressure - Hematoma > increased pressure causes vascular compromise,

Question 40

Prevention of Flap Necrosis

Answer 40

- Hemostasis - presurgical planning of the skin flap - understanding of regional anatomy - Proper skin manipulation - Skin hooks decrease the amount of direct flap manipulation - avoid a beveled skin cut - Doppler ultrasonography to ensure its location - The use of sterile markers and rulers

Question 41

Monitoring Flaps

Answer 41

- Subjectively, color, warmth, and bleeding - Experimentally, when a flap is devoid solely of arterial supply, it has a pale appearance. - A flap that is devoid solely of venous drainage becomes engorged and cyanotic - Most skin flaps will declare themselves with obvious color changes **by the end of 6 days** - Because flaps are denervated when they are harvested, sensation may be disrupted. - Bleeding at the skin edges is considered to signify a healthy flap - - Objectively, laser Doppler flowmetry and fluorescein > conflicting reports as to their significance.

Question 42

Salvage of Failing Flaps

Answer 42

- under too much tension, its borders can be released - Flap edges can be left to heal by second intention, or a delayed primary or secondary closure - If infection > culture of a tissue sample from the wound bed - Assess for exacerbating factors (trauma, motion, local compression, severe anaemia) - NPWT > not well reported in veterinary literature

Question 43

Buccal transposition flap for closure of maxillary lip defects in 5 dogs Hildebrandt 2023

Answer 43

- perfused by branches of the angularis oris artery and superior labial artery. All flaps survived. Three dogs developed postoperative complications, including oronasal fistula (n = 2) and partial flap dehiscence (n = 1). The cosmetic and functional outcomes were considered satisfactory in all cases.

Question 44

Sternohyoideus-sternothyroideus muscle flap to reconstruct oronasal fistulas due to maxillary cancer in four dogs Ciepluch 2023

Answer 44

Client-owned dogs (n = 4) with oronasal fistulas related to cancer. Flaps were harvested by transecting the ipsilateral sternothyroideus and sternohyoideus muscles from their origin at the manubrium and costal cartilage. The muscles were rotated around the base of the cranial thyroid artery and tunneled subcutaneously in the neck and through an incision in the caudodorsal aspect of the oral cavity. All dogs had partial dehiscence of the flap. Conclusion: This flap was associated with a high rate of complications;

Question 45

Random mucosal rotating flaps for rostral to mid maxillary defect reconstruction: 26 dogs (2000-2019) M. Carroll 2023

Answer 45

(transposition or interpolation Twenty-six client-owned dogs were retrospectively included Three dogs (11.5%) experienced minor complications consisting of flap dehiscence, and three dogs (11.5%) developed extensive flap necrosis complications appear to be more likely when these flaps are used to close mid maxillary defects. The donor site was left open to heal by second intention in 25 dogs. No dogs treated with the double RMTF technique experienced postoperative complications labial and cheek mucosa > regions receive rich vascularisation derived from both the facial and the infraorbital arteries. The infraorbital artery is the main continuation of the maxillary artery and anastomoses with the superior labial artery, thus creating a large muscolomucosal plexus

Question 46

Use of near-infrared fluorescence angiography with indocyanine green to evaluate direct cutaneous arteries used for canine axial pattern flaps Eiger 2024

Answer 46

omocervical (OMO), thoracodorsal (THO), and caudal superficial epigastric (CSE); Experimental study. Animals: A total of 15 healthy, client-owned dogs CSE flap was most visible can be used for real-time identification of direct cutaneous arteries of some APFs and their associated angiosomes, ** OTHER STUDY: NIRF successful for caudal auricular flaps in two cats

Question 47

Full-thickness labial flaps to reconstruct facial defects in four dogs Pavletic 2021

Answer 47

lip-to-lid variation (also known as lip-to-nose) restored the right nostril and nasal planum after mast cell tumor resection in one dog. In three dogs, the nasal defects were reconstructed with full-thickness upper labial transposition flaps full-thickness labial advancement flap (composite flap) Supplied by the superior labial artery and vein,

Question 48

Angularis oris axial pattern flap as a reliable and versatile option for rostral facial reconstruction in cats Albernaz 2021 | oblak

Answer 48

angularis oris AFP in 9 cats, 10 flaps - complications: short-term: oedema 10/10 (100%), dehiscence 3/10 (30%), distal necrosis 3/10 (30%) long-term: epiphora, frequent grooming, corneal ulceration Tumor recurrence occurred in 3 cases.

Question 49

Superficial temporal axial pattern flap for facial reconstruction of skin defects in dogs and cats B. de la Puerta 2021

Answer 49

superficial temporal AFP in 9 dogs and 10 cats - indications: neoplasia 94.7%, fungal granuloma 5.2% (1/19) - complications: (42.1%), 1/19 (5.2%) major → full thickness partial necrosis - major complication associated with flap length exceeding recommended - 4/19 (21%) minor – partial thickness necrosis, oedema, wound discharge - 100% flap survival in 17/19 (89.4%)

Question 50

Lip-to-nose flap for reconstruction of the nasal planum after curative intent excision of squamous cell carcinoma in cats: Description of technique and outcome in seven cases Massari 2020

Answer 50

No major complications occurred during the healing process, and all cats went on to achieve successful healing of their flap. A small area of partial-thickness necrosis developed at the cranial edge of the flap in three cats

Question 51

Reverse Saphenous Conduit Flap in 19 Dogs and 1 Cat cavalcanti 2018

Answer 51

other options include second-intention healing, releasing incisions, skin flaps, free skin grafts, tissue expansion, and microvascular free tissue transfer. majority of cases had medial shearing injuries All animals had complete flap survival. In five animals (20%), minor donor site dehiscence occurred, which did not require surgery.

Question 52

Hard palate defect repair by using haired angularis oris axial pattern flaps in dogs Nakahara 2020 | straw

Answer 52

HAOF can be used to reconstruct caudal and central hard palate defects extending to the maxillary canine teeth. Its clinical use led to successful closure of such defects in three dogs.

Question 53

Is the caudal auricular axial pattern flap robust? A multi-centre cohort study of 16 dogs and 12 cats (2005 to 2016) Proot 2019

Answer 53

- complications: wound dehiscence without necrosis: 6% dogs, 8% cats wound dehiscence with necrosis: 63% dogs, 42% cats - revision: 50% dogs, 25% cats - outcome: uncomplicated healing 31% dogs, 50% cats

Question 54

Evaluation of the Superior Labial Musculomucosal Flap in Dogs: An Angiographic Study and Case Report Cody P. Doyle 2019

Answer 54

The musculomucosal flaps of the superior and inferior labia contain a rich arterial blood supply, which suggests that these flaps may survive in live dogs. The superior labial musculomucosal flap was successfully used to reconstruct a large cleft palate in a single clinical case. Bryant and colleagues have described the use of amucosal flap from the lip commissure based on the angularis oris artery.13 This flap can be created as an island flap for palatine defect reconstruction.We proposed to take this concept one step further and create a superior lip musculomucosal flap based on the superior labial artery and vein

Question 55

Genicular artery axial pattern flap for reconstruction of skin defects in 22 dogs T. Emmerson

Answer 55

lateral and cranial crus wounds in 22 dogs - flap survival: mean 99.1% - complications: major: 3/22 (13.6%) - 2/22 (9.1%) distal flap necrosis, 1/22 dehiscence minor: 8/22 (36%) - minor dehiscence, seroma, infection

Question 56

Outcome of caudal superficial epigastric axial pattern flaps in dogs and cats: 70 cases (2007-2020) K Forster 2022

Answer 56

caudal superficial epigastric AFP in 51 dogs, 19 cats - dogs: complications: 67% overall, 59% minor, 8% major - dehiscence 31%, necrosis 29%, seroma 26%, oedema 26%, infection 16% - cats: complications: 53% overall, 47% minor, 5% major - dehiscence 26%, necrosis 16%, seroma 11%, oedema 0%, infection 5% - outcome: dogs: 77% good, 4% poor → 19% revision rate, 4% total flap failure cats: 79% good, 0% poor → 21% revision rate

Question 57

Outcome of superficial brachial axial pattern flaps used to close skin defects in dogs: 16 cases (1996-2019) E. Villedieu 2022

Answer 57

- elevation: 75-110% of described max angiosome - indications: 94% neoplasia, 6% non-healing olecranon wound - complications: 100% dogs, 44% dehiscence, 38% partial necrosis, 13% complete necrosis - complete necrosis in 2 dogs with extension of flap to carpus - 31% seroma, 19% oedema - 50% healed without revision or open wound management - 3/16 (19%) revision