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Ростовский Государственный Медицинский Университет

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Медицина общая

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stage before being removed in the second stage Island pedicle: all borders incised with no attachments to the donor site while maintaining original blood supply

Distal flap (free flap): not in the region of the defect; detached from original blood supply at donor site and reattached to blood vessels in defect site

TISSUE COMPOSITION (TABLE 3-3)

TABLE 3-3 Indications of Flaps of Different Tissue Composition*

Cutaneous flap

Blood supply: dependent on blood supply from

fasciocutaneous plexus

Flap design

Method of transfer: advancement, pivotal, or hinge Random pattern flaps

*Size limited to length to width ratio ~2:1 in lower extremity and up to 4:1 in head and neck.

Ischemia can be expected when the recommended length to width ratio dimensions are exceeded without performing a flap delay.

Fascial and fasciocutaneous flap

Blood supply: Mathes and Nahai classification (see Fig. 3-

Flap design

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Includes deep fascia, incorporating rich vascular fascial plexus that reach the skin via direct or indirect perforators. Type A and B pedicles are relatively constant in location; type C pedicles have more variability in location. Fascia-only flaps advantageous because donor site can be closed primarily; fasciocutaneous flaps may or may not require skin graft to close donor site. Can be used as pedicled or free flaps.

Workhorse fasciocutaneous flaps (Table 3-4)

TABLE 3-4 Workhorse Fasciocutaneous Flap*

Muscle/musculocutaneous flap

Blood supply/Mathes and Nahai classification (Fig. 3-3)

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Figure 3-3 Mathes and Nahai classification of musculocutaneous flaps. (From Mathes SJ , Nahai F.

Classification of the vascular anatomy of muscles: experimental and clinical correlation. Plast Reconstr Surg. 1981;67(2):177-187.)

Type I: single vascular pedicle (eg, gastrocnemius, tensor fascia lata) Type II: single dominant pedicle and one or more minor pedicles; flap cannot survive on minor pedicles alone; most common type of muscle in body (eg, soleus, gracilis, rectus femoris, biceps femoris)

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Type III: two dominant pedicles; flap can survive on either pedicle alone (eg, rectus abdominis, gluteus maximus) Type IV: segmental pedicles; multiple pedicles enter along course of muscle, each supplies a portion of the flap; least reliable type (eg, sartorius, tibialis anterior) Type V: one dominant pedicle and secondary segmental pedicles; flap can survive on segmental pedicles alone (eg, latissimus dorsi, pectoralis major)

Flap design

Skin island is designed to include skin perforators arising from the source artery. Musculocutaneous perforators typically located near entry of dominant pedicle into hilum of the muscle. All or part of muscle can be used as a flap. May also include bone, motor nerve, or sensory nerve in transfer (depending on donor muscle). Functional muscle is sacrificed, thus donor morbidity must be considered when selecting flap.

Workhorse musculocutaneous flaps (Table 3-5)

TABLE 3-5 Workhorse Musculocutaneous Flaps

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Other flap types include osseous/osteocutaneous/osteomusculocutaneous flap and omental flaps. Perforator considerations

Can identify perforators preoperatively by color duplex ultrasound, computerized tomography (CT) angiogram, or handheld audible Doppler Can increase length of pedicle by dissecting perforator back to its origin

FLAP MODIFICATIONS

Flap Delay

Staged technique to augment flap circulation and improve flap survival. Flap is partially or entirely elevated, or selected pedicles are divided in one or more procedures; flap is brought back to in situ position in staged procedure before definitive flap elevation and transfer ~2 weeks after delay procedure. Allows harvest of larger flap because areas farthest from blood supply (random-supply component) have improved perfusion following delay. Physiology of improved perfusion with delay

Decrease in sympathetic tone from transection of sympathetic fibers.

*Dilation of previously closed choke vessels increases the area of tissue supplied by the dominant pedicle.

Relative tissue ischemia stimulates angiogenesis, increasing flap vascularity.

Crane Principle

Pedicled flap used to lift, transport, and deposit subcutaneous tissue to recipient bed. Flap is raised and transferred to recipient bed. After 10-21 days, new blood vessels have grown in the recipient bed, which will support a skin graft. In the next

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stage, the top layer (superficial one-half to three-fourths) is raised and returned to original donor site. Viable subcutaneous tissue is left behind and can be covered with skin graft. Provides coverage to local or regional area without significant donor site morbidity.

Prelamination

Introduction of additional tissue layers into flap prior to transfer to create multilayer composite flap; allows tissue to have time to mature before transfer Indication: allows custom-made flaps for specialized areas of the body with 3D structure (eg, central face, penis) Two-stage process

Stage 1: modify donor flap by introducing additional tissue layer into vascularized tissue before transfer to recipient site (eg, introduce cartilage and/or skin grafts to forehead flap before transfer to the defect). Stage 2: raise flap en bloc as composite flap and transfer to recipient site after ~2-4 weeks (shorter maturation time than prefabrication because vascular supply is not altered).

Supercharging

Enhances blood supply of a pedicled free flap by performing additional microvascular anastomosis to free flaps. Example: transverse rectus abdominis musculocutaneous flap with classic superior epigastric artery pedicle that also has deep inferior epigastric artery anastomosed to vessels in the axilla, neck, or chest to enhance blood supply.

Composite Flaps

Angiosome principle provides basis for transfer of

composite flaps that contain combinations of multiple tissue types (eg, skin, muscle, bone, nerve, and/or tendon). Tissues supplied by single source artery can be transferred together. Useful when reconstruction of multiple tissue components is needed.

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Vascularized bone flaps

Blood supply classification (Serafin)

Direct (endosteal) circulation Indirect (periosteal) circulation

Commonly transferred bones and their vascular pedicles

Radius: radial artery Fibula: peroneal artery Scapula: circumflex scapular or thoracodorsal artery Iliac crest: deep circumflex iliac artery Great toe/second toe transfer: first dorsal metatarsal artery

Innervated flaps

Motor nerve and/or sensory nerves are preserved or coapted to appropriate nerve near the recipient site. Common functional muscle flap transfer and their motor nerve

Gracilis with obturator nerve Latissimus with thoracodorsal nerve Pectoralis minor with medial and lateral pectoral nerve

Common sensory flaps with their sensory nerves

Lateral arm flap with posterior brachial cutaneous nerve Radial forearm flap with medial and/or lateral antebrachial cutaneous nerves Dorsalis pedis flap with deep peroneal nerve and/or superficial peroneal nerve

Chimeric vs Conjoined (Siamese) Flap

Chimeric flap: has multiple territories, each with

independent vascular supply (perforators or named branches), but territories are NOT connected except by connection to common source vessel. Conjoined flap: has multiple territories, each with independent vascular supply, but territories remain connected.

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POSTOPERATIVE MANAGEMENT

Flap Monitoring

*Evidence of arterial or venous insufficiency in immediate post-op period requires immediate exploration (Table 3-6).

TABLE 3-6 Signs of Arterial and Venous Insufficiency

If venous congested, unwrap, release sutures and consider leech therapy (patient must be on third-

generation cephalosporin, quinolone or trimethoprim/sulfamethoxazole against

Aeromonas)

*Clinical evaluation: gold standard method of flap assessment

Temperature: should be body temperature Color: should be pink Capillary refill: should be ~2-3 seconds Bleeding: upon introduction of fine-gauge needle, bright-red bleeding should be present Firmness: should be soft, with some appreciable turgor

Additional methods of flap monitoring

Doppler (implanted or external) Near-infrared spectroscopy for tissue oxygen saturation (Vioptix)—measures tissue oxygen saturation (StO2)

Fluorescein dye

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pH or temperature sensors

Risk Factors for Flap Vascular Compromise

Tight dressings and/or splints Tight sutures Patient position or motion that puts pressure on flap Hematoma (increases tissue pressure and interferes with perfusion) Kinking of flap, pedicle, or both (may be influenced by flap design, pedicle length, interpositional vein graft length) Poor surgical technique Systemic patient factors: use of vasoconstrictive pharmaceutical agents (vasopressors, nicotine, caffeine, etc.), hypovolemia, anemia, inadequate blood pressure

PEARLS

1. In most situations, follow the reconstructive ladder when deciding if a flap is needed for your reconstruction and what type of flap

2. Always consider both patient factors (I.e. patient comorbidities and goals) and surgical factors (I.e. defect characteristics and donor site considerations) when deciding the appropriate flap

3. Know how to evaluate a flap postoperatively and be able to detect flap compromise

QUESTIONS YOU WILL BE ASKED

1. What is the most common (Mathes and Nahai) type of muscle flap in the body? Type II (major and minor pedicle).

2. What is the physiology behind improved perfusion after flap delay? Flap perfusion is increased through (1) decrease in sympathetic tone from transection of sympathetic fibers; (2) dilation of previously closed choke vessels, which increases the area of

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tissue supplied by dominant pedicle; and (3) relative tissue ischemia stimulates angiogenesis, increasing flap vascularity before transfer.

3. What is the pedicle to the flap?

Table 3-3.

4. What is difference between a type II and type V flap? Type II flap has secondary pedicle that cannot support the flap alone. Type V flap can be transferred on the secondary pedicles which are segmental.