CHAPTER 13: FLAPS

Question 1

Medial plantar flap - anatomy & usage

Answer 1

Cutaneous flap of glaborous skin
Artery - medial plantar perforator (landmark = medial cuneiform plantar surface) from medial plantar artery (from posterior tibial artery)
Veins - venae comitantes & superficial veins
Sensory - medial planatar or saphenous branch (if present)

Locate PT artery at behind medial malleolus
Tom, Dick ANd Harry - from ant to post
1. Tib post
2. FDL
3. PT artery and tibial nerve
4. FHL

Flap usage

• small defects around medial malleolus, distal medial foot or medial first metatarsal head.
• Calcaneal defects if pedicle is traced back to PT

Question 2

Medial plantar flap - raising

Answer 2

Flap 7 x 2cm
Doppler perforator
- flap can be designed eccentrically (if used for local rotation) or centrally (if free)
Axis of flap = plantar edge of the first metatarsal, first cuneiform, and navicular

• First incision made at plantar aspect of flap
• Enter fascia over abductor hallucis is entered
• Raise flap from plantar to dorsal
• Perforators between abductor hallucis and flexor hallucis tendons are identified and preserved
• abductor hallucis muscle is retracted and the perforators are followed to their origin on the medial plantar system
• superficial vein is traced from dorsal incision
• donor site closed directly / SSG

Question 3

Flaps to look up

Answer 3

lateral arm flap

dcia

Question 4

Complications of free fibula flap

Answer 4

• leave at least 6cm of proximal fibula to avoid destabilising knee and damage to common peroneal nerve
• CT angiography is recommended, as peroneal artery may be dominant in 8% patients (peroneal arteria magna) / the only perfusing artery in PVD or trauma pts
• identify and preserve lesser saphenous vein and sural nerve for skin paddle
  can increase bone - bone contact with step / wedge osteotomy
• Include cuff of soleus muscle or flexor hallucis longus muscle to improve reliability of skin paddle if skin perforators are small
• 6 to 8 cm of distal fibula must remain intact to stabilise ankle. In skeletally immature patients, perform a syndesmosis at the lateral malleolus following fibula harvest
  Once fibula is visualised, dissection continues in a subperiosteal plane at superior margin of fibula until peroneal nerve is identified; then dissection may be continued superficial to periosteum to prevent iatrogenic deep peroneal nerve injury.
• tibial nerve and posterior tibial artery must be identified before ligating vessels and harvesting flap
• keep operating field dry during dissection of FHL off the fibula and peroneal vessels, visualise and ligate all branching vessels from the peroneal bundle.
• ensure pedicle is not compressed, twisted or kinked. Use wide exposure of recipient site and inset under clear visualisation. Cover pedicle with SG if necessary
• After preparing fibula for inset, perform 1-2cm subperiosteal dissection to separate pedicle of flap and prevent kinking
• unicortical screws prevent pedicle injury.

Question 5

What are the risks of free fibula flap?

Answer 5

• bleeding -> compartment syndrome
• damage to common? deep / superficial peroneal nerve
• sural nerve sacrificed - parasthesia lat foot and leg
• swelling, lymphoedema
• stiffness
• unstable ankle - problems with running
• flap failure

Question 6

What is a flap?

Answer 6

A unit of tissue that maintains its own blood supply while being transferred from a donor site to a recipient site.

Most flaps can be classified according to:

1. method of mvmt
2. vascularity
3. tissue composition

Question 7

What kinds of local flaps are there?

Answer 7

Advancement - slides directly forward into defect
Rotation - semicircular flap rotated about a pivot point into a defect to be closed
Transposition - rotated laterally about a pivot point into an immediately adjacent defect
e.g. Z plasty, rhomboid (Limberg), Dufourmentel

Interpolation - rotates on a pivot point into a defect, with pedicle passing over or under intervening tissue e.g. deltopectoral, Littler NV digital pulp flap

Question 8

What is a Z plasty?

What are the theoretical gains in length?

Answer 8

2 opposing triangular transposition flaps

Degrees            % gain in length
30                             25
45                             50
60                             75 
75                             100
90                             120

Question 9

What are distant flaps?

Answer 9

where donor and recipient sites are not close to one another
e.g. thenar, cross-leg, groin
When 2 sites cannot be approximated, flap can be ‘waltzed’

Question 10

What is a free flap?

Answer 10

a unit of tissue with an artery and vein is divided and reanastomosed at the recipient site with blood flow re-established

Question 11

what is an angiosome? Who described this?

Answer 11

Taylor and Palmer

- a composite unit of skin with its underlying deep tissue supplied by a source artery

Question 12

What is the fasciocutaneous plexus?

Who described the the different vessel types that perforate the deep fascia to supply the fasciocutaneous plexus?

Answer 12

A communicating network of subfascial, intrafascial, suprafascial, subcutaneous and sub dermal vascular plexuses

Nakajima

1. direct cutaneous branch of a muscular vessel
2. septocutaneous perforator
3. direct cutaneous
4. musculocutaneous
5. direct septocutaneous
6. perforating cutaneous branch of a muscular vessel

Question 13

Cutaneous flaps: how are they classified?

Answer 13

McGregor and Morgan

1. Random pattern: based off the subdermal plexus, limited to 3:1 length:width ratio
2. Axial pattern: contains a specific direct cutaneous artery within the longitudinal axis of the flap

(3. Reverse axial pattern flaps (reverse flow flap)
4. Island flap)

Nakajima: classified cutaneous flaps based on vascularisation

1. cutaneous (equivalent to axial flap)
2. fasciocutaneous
3. adipofascial
4. septocutaneous
5. musculocutaneous

Question 14

How are perforator flaps classified?

How are they named?

Answer 14

Direct / indirect

1. Musculocutaneous (indirect)
2. Septocutaneous (indirect)
3. Direct cutaneous (direct)

Named after nutrient vessel (e.g. DIEP) unless multiple flap can be raised from the nutrient vessel e.g. ALT flap from descending branch of lat circ femoral

Question 15

What are the advantages and disadvantages of perforator flaps?

Answer 15

Adv
numerous donor sites, versatile size and thickness
can incorporate muscle, fat bone into flap design
preserve muscle function
reduce donor site morbidity

Disadv
tedious pedicle dissection
perforator anatomy variable
increased risk of fat necrosis cf musculocutaneous flaps

Question 16

What other flaps do you know of?

Answer 16

Neurocutaneous & venocutaneous flaps - based on perforating arteries accompanying cutaneous nerves and veins (e.g. sural, saphenous)

Venous flaps - supplied through a venous pedicle
Type I - single-pedicled: in & outflow through single vein
Type II - bipedicled ‘flow-through’ flap
Type III - arterialised venous flap: artery anastomosed to vein proximally and vein outflow distally

Question 17

How are flaps classified by tissue composition?

Answer 17

Fascial and fasciocutaneous flaps
Muscle and myocutaneous flaps
Vascularised bone flaps
Visceral flaps
Innervated flaps
Compound and composite flaps 
Prefabridcated flaps

Question 18

Who classified fasciocutaneous flaps?

Answer 18

Mathes
Direct cutaneous pedicle
Septocutaneous
Musculocutaneous

Question 19

Who classified muscle flaps?

Answer 19

Mathes and Nahai
I One dominant pedicle
II Dominant pedicle & minor pedicle (s)
III Two dominant pedicles
IV Segmental pedicles
V One dominant & secondary segmental pedicles

I TFL
II Gracilis
III Rectus abdominis, gluteus maximus
IV Sartorius
V Latissimus dorsi

Question 20

Tell me about MC vs FC flaps

Answer 20

all demonstrate marked increase in blood flow
decrease in bacterial concentration MC>FC (count = 100 vs 10000)
collagen deposition MC>FC

Question 21

Bone flaps

Answer 21

supplied by their nutrient vessels
can reconstruct large defects, withstand DXT and implantation
e.g. fibula (peroneal artery), radius (radial), iliac crest (DCIA)

Question 22

Visceral flaps

Answer 22

e.g. jejunum, colon, omentum

Question 23

Innervated flaps: functional muscle and sensory flaps

Answer 23

functional muscle: motor nerve coated after free flap transfer
e.g. gracilis, LD, serratus, pec minor

Question 24

Compound and composite flaps

Answer 24

Contains diverse tissue components
Solitary composite
Siamese
Conjoint
Sequential

Question 25

Prefabricated flaps

Answer 25

2 stage technique where flap is surgically altered by partial elevation, structural manipulation and incorporation of other tissue layers in the 1st stage to create a specialised composite flap e.g. nasal recon

Question 26

How is blood flow to the skin regulated?

Answer 26

Systemic 1. Neural: sympathetic alpha adrenergic (vasoconstriction), beta adrenergic (vasodilatation). Cholinergic (bradykinin release, vasodilatation) 2. Humoral Vasoconstriction: adr, noradr, serotonin, thromboxane A2, PGF2alpha Vasodilatation: bradykinin, histamine, PGE1 Local (autoregulation) Metabolic Vasodilatation: hypercapnia, hypoxia, acidosis, hyperkalaemia Physical Vasoconstriction: myogenic reflex in response to distension of cutaneous vessels; local hypothermia and increased blood viscosity

Question 27

What happens to blood flow when a flap is transferred?

Answer 27

Homeostasis is disrupted, including - loss of sympathetic innervation - ischaemia (anaerobic metabolism, lactate, superoxide radical, changes in blood viscosity and clotting) Ischaemia induced reperfusion injury is direct cytotoxic injury from free radicals during flap ischaemia. Fat and bone can tolerate ~3hrs, muscle and GI mucosa much less.

Question 28

What is the theory of flap delay?

Answer 28

Flap delay: surgical interruption of a portion of the blood supply to a flap at a preliminary stage (10d - 3wks) before transfer 1. Conditions flap to ischaemia 2. Opens choke vessels Tissue expansion is also form of delay

Question 29

What are the 5 mechanisms of delay?

Answer 29

1. Sympathectomy 2. Vascular reorganisation 3. Reactive hyperaemia 4. Acclimatisation to hypoxia 5. Non-specific inflammatory reaction

Question 30

What factors contribute to increase flap survival?

Answer 30

Physical warm, well filled, pain free Pharmacological 1. Anticoagulants: heparin, thrombolysis (streptokinase, t-PA), leeches 2. Vasodilators: Ca channel blockers, topical GTN, topical lignocaine 3. Antiinflammatory agents: aspirin

Question 31

How are flaps monitored?

Answer 31

1. Clinical - subjective: colour, cap refill, warmth, turgor, scratch test Temp difference >3 degrees = significant 2. Vital dye Fluorescein 3. Photoelectric US doppler Doppler venous coupler Laser doppler 4. Metabolic transcutaneous O2 tension (measures O2 partial pressures) Photoplethysmography - pulse ox, infrared light measures fluid vol by different light absorption by skin, disappointing results clinically