Head & Neck Surgery - Otolaryngology
4th Edition

162
Microvascular Free Flaps in Head and Neck Reconstruction
Douglas B. Chepeha
Theodoros N. Teknos
Microvascular free-tissue transfer was introduced as a technique that allowed reconstruction of defects that could not otherwise be reconstructed. The viability of the revascularized tissue and the long operating time were initial concerns. During the 1980s, use of regional pedicled flaps (pectoralis, trapezius, latissimus dorsi) overshadowed microvascular free-tissue transfer. Regional flaps were technically much easier, required only one surgical team, and supplied nonirradiated tissue. Microvascular reconstruction continued to evolve. More flap sites were described each year, and the versatility of each site was explored and expanded. More surgeons were trained in microvascular techniques, and these surgeons became increasingly adept. As microvascular surgery became more widespread, it became clear that these transfers were reliable (95% to 98%) and represented only a 4- to 6-hour increase in operating time (1).
Controversy still exists about whether microvascular reconstruction is functionally superior to pedicled reconstruction of comparable defects. Intuition suggests that revascularized free-tissue transfer is functionally superior because it allows the reconstructive surgeon to customize reconstruction of defects of the head and neck. Free flaps can be designed to provide epithelium, subcutaneous tissue, muscle, nerve, and bone in proportions that closely resemble the missing tissue.
If microvascular reconstruction is functionally superior, is it cost effective? Several studies have suggested that use of pectoralis flaps are associated with longer hospital stays and higher complication rates than free-tissue transfer in comparable primary reconstructions (2). This suggests that the costs of longer operating times associated with free-tissue transfer may be offset by the longer hospitalizations associated with pedicled transfer.
The drive for reconstructive surgeons to provide the best functional and aesthetic reconstruction for their patients made revascularized free-tissue transfer the mainstay of head and neck reconstruction in the 1990s. Much research still has to be done to establish the value and exact place of these sophisticated reconstructive techniques in the various defects encountered in the head and neck.
This chapter is divided into two sections. The first section is an introduction to free-tissue transfers commonly used in head and neck reconstruction (Table 162.1). Each flap is described in terms of design and use, anatomic characteristics, anatomic variations, potential morbidity, technical considerations, preoperative considerations, and postoperative management. The second section is an introduction approach to commonly encountered defects of the head and neck.
Fascial and Fasciocutaneous Flaps
Radial Forearm Flap
Flap Description
The radial forearm free flap is a thin fasciocutaneous flap based on the radial artery and its venae comitantes and the
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cephalic vein (Fig. 162.1). This flap can be transferred as a composite flap that contains vascularized bone, vascularized tendon, the brachioradialis muscle, and vascularized nerve. The skin of the entire forearm, from the antecubital fossa to the flexor crease of the wrist, can be harvested. The vascular pedicle is long (20 cm) and the artery is 2 to 2.5 mm in diameter. The radial forearm free flap is a source of well-vascularized, thin, pliable skin with the potential for sensory reinnervation. It can be used to reconstruct small (<60 mm) to moderate volume (<200 cm2) defects. The flap can be folded to facilitate sophisticated reconstructions and is a souce of a small amount of vascularized bone. This flap is used most often in reconstruction of the oral cavity and base of the tongue, partial and circumferential reconstruction
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of the pharynx, and reconstruction of the soft palate. It also can be used to manage cutaneous defects of the eye, lip, neck, and scalp. When transferred as a fascial flap, the radial forearm free flap can be used to manage soft-tissue defects and defects of the base of the skull, particularly for a previously treated patient, and local pericranial flaps are not available (3). When the flap is transferred as an osteocutaneous flap, a segment of radius 10 to 12 cm long and as much as 40% of its circumference can be harvested with overlying fascia and skin. This flap is useful for reconstruction of small-volume bone and soft-tissue defects of the face, such as the periorbital tissues, particularly if the patient has undergone or is to undergo radiation therapy (4). The disadvantages of use of the radial osteocutaneous flap are the limited amount of bone available and the risk of pathologic fracture of the radius.
TABLE 162.1 MICROVASCULAR FREE SOFT-TISSUE FLAP SELECTION IN HEAD AND NECK RECONSTRUCTION
Flap Quality Advantages Disadvantages
Radial forearm Thin, pliable Versatility, ease Limited bulk, skin-graft donor site
Lateral arm Moderately thin Primary closure of donor site Small-caliber pedicle
Lateral thigh Moderately thick Large surface area of tissue, long pedicle Challenging harvest
Anterolateral thigh Thin, pliable Long pedicle, large cutaneous component Muscle associated with musculocutaneous component
Temporoparietal fascia Ultrathin Can be transferred as pedicle flap Challenging harvest, limited pedicle length
Rectus Bulky Versatility, ease of harvest Risk of ventral hernia
Latissimus dorsi Moderate bulk Large surface area, ease of harvest Lateral decubitus position
Gracilis Thin muscle Can be separated into functional units Limited tissue available
Figure 162.1 Lateral view shows left lateral forearm. The flap axis is slightly medial to the radial artery, and the flap is positioned to include the cephalic vein over the extensor compartment. Nutrient branches to the radius are immediately deep to the brachioradialis tendon. The superficial branch of the radial nerve is preserved in dissection of this flap.
Neurovascular Pedicle
The radial artery, with its two venae comitantes courses in the lateral intermuscular septum and has several fascial branches in the forearm (5). This fascial plexus supplies most of the skin in the forearm. The length of the arterial pedicle is limited by the radial recurrent artery, which is the first major branch of the radial artery after its takeoff from the brachial artery. The flap has a deep venous supply through the paired venae comitantes and the larger superficial veins, such as the cephalic vein. Numerous connections exist between the venae comitantes and the superficial venous system; these vessels provide excellent venous drainage of this flap. If necessary, and if proper testing of the venous drainage of the flap is conducted after elevation, it usually is possible to drain the flap through the superficial system alone. It is nearly always possible to drain the flap through the venae comitantes alone. The lateral antebrachial cutaneous nerve is the primary sensory nerve to the territory of forearm skin most commonly harvested. This nerve typically courses close to the cephalic vein in the upper forearm. When sensory reinnervation is needed, this nerve can be easily anastomosed to the recipient sensory nerve.
Anatomic Variations
The greatest concern in harvest of the radial forearm flap is the integrity of the ulnar arterial supply to the hand through the palmar arches. The combination of two concurrent arterial variations, an incomplete superficial palmar arch, and a lack of communication between the superficial and deep palmar arches puts the vascular supply of the thumb and index finger in jeopardy (6). This anomaly can be detected with an Allen test. This test involves assessment of capillary refill of the thumb and index finger with the radial artery occluded. The patient is asked to clench his or her fist. The examiner uses digital pressure to occlude the radial and ulnar arteries at the wrist. The patient opens the hand to approximately 10 degrees of flexion, the examiner releases the ulnar artery, and capillary refill is assessed. If there is uncertainty about digital blood flow during capillary refill assessment, Doppler assessment of the digital artery is performed, and the results are definitive.
Potential Morbidity
Often the donor site cannot be closed primarily, and a skin graft is necessary, which can be unsightly. Poor take of the skin graft can be caused by inadequate immobilization of the hand or failure to preserve the paratenon over the flexor tendons. Radial osteocutaneous flaps are limited by risk of fracture of the radius and a detrimental effect on supination, wrist flexion, grip strength, and pinch strength (7).
Technical Considerations
The design of a radial forearm flap begins with an outline of the path of the dominant subcutaneous veins and the palpable pulse of the radial artery. The flap is oriented over the radial artery and cephalic vein. It is preferable not to elevate the flap over the ulnar artery. Additional subcutaneous tissue can be incorporated into the flap when needed. During flap harvest, the paratenon over the flexor tendons is preserved to facilitate skin graft healing. If necessary, the flexor tendons can be covered with turnover muscle flaps to improve the donor-site bed for skin grafting.
Preoperative Considerations
Accurate performance of an Allen test is the most important consideration in avoiding the catastrophic complication of ischemia of the hand. When the Allen test results are equivocal, the opposite hand or an alternative flap is selected. When the patient has had an indwelling radial artery catheter, it is prudent to select another donor site.
Postoperative Management
After a fasciocutaneous flap, the forearm and wrist are immobilized with a volar splint with the wrist in the position of function for 6 to 7 days. Then a removable volar plastic splint is used for an additional 3 to 5 weeks until the skin graph is healed over the donor site. After an osseocutaneous flap, the elbow and wrist are immobilized with a full arm cast with the hand in the positon of function. This cast is left on for 4 weeks, then the wrist is immobilized with a forearm cast, and this is left on for an additional 2 weeks. The patient is encouraged to use the arm throughout the casting period. The underlying philosophy is to allow time for reshaping of the load lines in the radial bone. Any limb with circumferential dressing needs to be closely observed in the immediate postoperative period for signs of vascular insufficiency.
Lateral Arm Flap
Flap Description
The lateral arm flap is a moderately thin fasciocutaneous flap that can be reinnervated for cutaneous sensation with the posterior cutaneous nerve of the arm (8). Unlike the procedure for radial forearm flap, the donor site usually can be closed primarily when the width of harvested skin
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is limited to 6 to 8 cm, or one-third the circumference of the arm. Larger flaps have been harvested and necessitate that a skin graft be placed over the donor site. The flap can be harvested as a fascial flap and is a good source of vascularized tissue for augmentation of subcutaneous defects caused by lateral temporal bone resection or total parotidectomy (9). The flap can include the posterior cutaneous nerve of the forearm for use as a vascularized nerve graft. The application of the lateral arm flap is affected by the body mass index of the patient and the placement of the flap. In patients with a lower body mass index (BMI), the lateral arm can be used for low-volume oral cavity, low-volume oropharyngeal, and low-volume cutaneous defects. In patients with higher BMI, the latereal arm flap can be used for higher volume base of tongue, lateral oropharynx including the parapharyngeal space, anterior oral glossectomy, lateral temporal bone, parotid and mid facial defects (10). The thickness of the flap can be varied with flap placement, as the skin over the lateral epicondyle is much thinner than the skin over the mid upper arm. When estimating volume, it is important to remember that the subcutaneous tissue over the deltoid is more prone to long-term atrophy than the subcutaneous tissue over the mid lateral arm. Many of the applications of the lateral arm flap have been supplanted by the anterolateral thigh flap because of its larger, longer pedicle and ease of primary closure. In situations where estimation of volume is critical, the lateral arm may be a better choice than an anteroleteral thigh because of the unpredictable volume of muscle that may be included in an anterolateral thigh flap.
Neurovascular Pedicle
The vascular supply of the lateral arm flap is based on the terminal branch of the profunda brachii artery and the posterior radial collateral artery and its venae comitantes, which travel with the radial nerve in the spiral groove of the humerus. The blood supply to the skin is derived from four to five septocutaneous perforators that arise from the posterior radial collateral artery in the lateral intermuscular septum. In the region of the deltoid insertion, where the posterior radial collateral artery enters the lateral intermuscular septum, the artery has an average diameter of 1.55 mm (range: 1.25 to 1.75 mm) and a maximum pedicle length with additional dissection of 8 to 10 cm (11). Additional pedicle length and caliber can be obtained by means of extending the dissection proximally between the lateral and long heads of the triceps muscle. The muscular branches from the radial nerve to the triceps muscle must be identified and preserved when this approach is used. In practice, it is difficult to obtain more than 4 to 5 cm of pedicle length without detaching a large amount of triceps and risking damage to the motor branches to the triceps muscle. To accommodate the fairly short pedicle, the flap can be moved to a more distal location over the lateral epicondyle. A second superficial venous system incorporates the cephalic vein but is rarely used in practice. Two sensory nerves are encountered during elevation of the flap; each arises from the proximal portion of the radial nerve. The nomenclature of these sensory nerves is confusing. The nerve that supplies sensation to the skin of the lateral arm flap is the posterior cutaneous nerve of the arm (also called the lower lateral cutaneous nerve of the arm and the inferior lateral brachial cutaneous nerve). The posterior cutaneous nerve of the forearm (also called the posterior antebrachial cutaneous nerve) runs through the lateral arm flap to the forearm and can be used as a vascularized nerve graft. A variable area of cutaneous anesthesia over the mid extensor surface of the forearm results.
Anatomic Variations
Unlike the radial forearm flap, the lateral arm flap does not affect the circulation to the distal portion of the arm. The profunda brachii artery can be interrupted without ischemic sequelae. The incidence of duplication of the profunda brachii artery ranges from 4% to 12% in different series.
Potential Morbidity
The radial nerve, which lies in the spiral groove of the humerus, is identified and protected from injury during flap harvest. Postoperative radial nerve palsy has been attributed to constrictive dressings or tight wound closure. Use of split-thickness skin grafts is preferable to exceedingly tight primary closure.
Technical Considerations
The lateral intermuscular septum is approximately 1 cm posterior to a line drawn from the insertion of the deltoid muscle and the lateral epicondyle. The central axis of the flap design is based on the intermuscular septum (Fig. 162.2). Preservation of the occiptal artery as it crosses the internal jugular vein helps reduce the challenges with pedicle length and size match in lateral reconstructions.
Preoperative Considerations
The thickness of the flap is assessed by means of palpation. The flap thins and becomes more pliable the more distally it is positioned on the upper arm. By means of measurement, one can determine the width of cutaneous paddle that can be harvested and closed primarily (one-third the circumference of the upper arm).
Postoperative Management
The donor site usually can be closed primarily with minimal undermining. A suction drain is recommended. If a skin graft is used, a volar slab is fashioned and the donor site is managed in a manner similar to the radial forearm donor site.
Lateral Thigh Flap
Flap Description
The lateral thigh flap was popularized by Hayden (12), who found it useful in head and neck reconstruction. For
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selected patients with favorable body habitus, this donor site provides a large surface area of expendable tissue with an adequate vascular pedicle. Flaps as large as 25 × 14 cm have been transferred successfully (13). This fasciocutaneous flap ranges from thin to moderately thick, depending on the patient’s body habitus. This flap is most useful for intraoral and pharyngeal reconstruction. With reinnervation, it is possible to restore sensation to the cutaneous portion of the flap through use of the lateral femoral cutaneous nerve. This flap is technically challenging and has been supplanted by the anterolateal thigh flap, which is technically easier to harvest and has a long vascular pedicle.
Figure 162.2 A: The flap is marked over the lateral epicondyle and 1 cm dorsal to a line drawn from the tip of the deltoid muscle to the lateral epicondyle. This position maximizes pedicle length and centers the flap over the lateral intermuscular septum. B: Cross section shows upper arm at the level shown in A. The lateral arm flap is elevated but still attached by the intermuscular septum to the humerus. At this level, the posterior cutaneous nerve of the arm is in the subcutaneous fat, whereas the posterior cutaneous nerve of the forearm still is in the intermuscular septum. C: Lateral view shows lateral arm flap, with the pedicle still in continuity. The radial nerve crosses the humerus and enters the cleft between the brachialis and the brachioradialis muscles.
Anterolateral Thigh Flap
Flap Description
The anterolateral thigh flap is a septocutaneous or musculocutaneous flap based on the descending branch of the lateral circumflex femoral artery and its associated venea comitantes. This flap can be harvested with any of the structures supplied by the common pedicle of the lateral femoral circumflex vessels. The flap can include the tensor fascial lata, vastus lateralis, and/or the rectus femoris. The flap can be harvested as large as 20 × 15 cm. The skin is thin and pliable in most males, whereas in females, this flap can be thicker, depending on the pattern of fat deposition in the thigh. The anterolateral thigh flap has become one of the workhorse flaps for soft-tissue reconstruction in the head and neck. It has many of the same characteristics as a radial forearm flap, such as thin pliable skin and a long vascular pedicle. The anterolateral thigh flap is larger and usually has slightly more subcutansous tissue than a radial forearm flap and as a result has been nicknamed its “big brother.” The nerves for sensation are the anterior femoral cutaneous and the lateral femoral cutaneous and run axially in the flap. The applications for this flap include face, neck, full-thickness buccal, hemiglossectomy, subtotal
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glossectomy, oropharynx, total pharyngeal, and skull base defects (14). The donor site is closed primarily when the flap is less than 9 cm in width. The disadvantage is the variable pedicle, which makes the volume of the flap unpredictable. A musculocutaneous pedicle may require inclusion of the larger portion of vastus lateralis, which will involute over the first year and can negatively impact volume-sensitive reconstructions. A perforator-based flap is an alternative, but the dissection is tedious and the free-tissue transfer becomes less reliable.
Figure 162.3 A: Type I vertical musculocutaneous perforator, which is the most common variant. B: Type III septocutaneous perforator.
Neurovascular Pedicle
The pedicle is located on a line drawn from the anterior superior iliac spine to the lateral edge of the patella. The perforators are usually at the junction of the upper and middle thirds of the line. A Doppler probe is used to locate the perforators.
Anatomic Variations
There are four patterns of vascular supply to the skin paddle (15). There are two musculocutaneous types, the vertical musculocutaneous (50%) and the horizontal musculocutaneous (30%), and two septocutaneous types, the vertical septocutaneous (15%) and the horizontal septocutaneous (5%) (Figure 162.3A and B).
Potential Morbidity
There is little morbidity reported, even with harvest of large portions of the vastus lateralis. With more long-term follow-up, morbidity will become better defined.
Technical Considerations
There is wide variablility in the amount of muscle that needs to be harvested with a musculocutaneous perforator flap. The pedicle is first identified with the medial incision, but the perforators are identified with the lateral incision as they pass through the vastus lateralis into the skin paddle. Once the perforators are identified, a strip of muscle is harvested that incorporates these musculocutaneous perforators.
Preoperative Considerations
A history of vasculopathy with bypass grafts is a contraindication. For some reconstructions, a larger muscle component
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may not be desirable. If a large muscle component is not desirable, an alternative site should be prepped out in the event the musculocutaneous perforators require a large muscle component. Perforator-based flaps are possible in patients with a large muscle component but are tedious and have a slightly higher failure rate.
Postoperative Management
The site can usually be closed primarily after the muscles have been approximated over a suction drain. Little rehabilitation is needed other than ambulation.
Temporoparietal Fascial Flap
Flap Description
The temporoparietal fascial flap has gained popularity in reconstruction of defects of the head and neck. In head and neck reconstruction, the fascia is most commonly transferred as a pedicled flap, but it also can be used as a free flap when the arc of rotation is inadequate. The temporoparietal fascial flap is ultrathin, highly vascular, pliable, and durable. The flap can be transferred independently or in combination with skin. The temporoparietal fascial flap can be harvested with dimensions of 17 × 14 cm, with extensive scalp undermining. The thickness of the flap ranges from 2 to 4 mm. As a free-tissue transfer, this flap has highly specialized uses for hemilaryngeal reconstruction, or a low-volume cutaneous reconstruction when the forearm sites are not available. Most often, it is used as a rotational flap in the midface, upper face, skull base, or lateral temporal bone to cover bone, support dural closure, or support calvarial bone grafts.
Figure 162.4 A: Cross section shows layers of the temporal scalp, superficial temporal space, and temporal skull. The superficial side of the temporoparietal facial flap is intimately associated with the subcutaneous fat of the scalp. The superficial dissection is started inferiorly just below the level of the hair follicles. As it proceeds superiorly, dissection becomes more difficult. Arrow denotes the deep side of the temporoparietal flap. B: Lateral view of the head with the temporoparietal flap folded inferiorly shows the vascular anatomic features. Dissection of the deep layer of the flap is in loose areolar tissue and is much more straightforward than is superficial dissection. Superficial dissection is completed before deep dissection.
Neurovascular Pedicle
The temporoparietal scalp consists of five distinct layers (Fig. 162.4A). The temporoparietal fascia is deep to the skin and subcutaneous tissue, to which it is firmly bound. The temporoparietal fascia is superficial to the temporalis muscular fascia, which envelops the muscle. Above the superior temporal line, the temporoparietal fascia becomes the galea aponeurotica (16). The superficial temporal artery and vein, which supply this flap and travel within the temporoparietal
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fascial layer, are best isolated approximately 3 cm superior to the root of the helix, where the vessels branch into frontal and parietal divisions. The flap is most commonly based on the parietal branch. The base is centered over the middle third of the superior auricular helix. The frontal branch of the superficial temporal artery is routinely ligated 3 to 4 cm distal to its separation from the parietal branch to avoid injury to the frontal branch of the facial nerve. The middle temporal artery arises from the proximal superficial temporal artery at the level of the zygomatic arch and supplies the temporalis muscular fascia. If the middle temporal artery is included, a two-layered fascial flap can be raised on a single vascular pedicle (Fig. 162.4B).
Anatomic Variations
The superficial temporal artery consistently divides into two branches 3 cm above the root of the helix. Tracing the course of the posterior parietal branch with Doppler sonography ensures that the planned territory of the temporoparietal fascial flap is well vascularized.
Potential Morbidity
The anterior dissection of the flap is limited by the course of the frontal branch of the facial nerve, which also is in the temporoparietal fascia. Secondary alopecia can be caused by injury to the hair follicles by dissection that is too superficial. The venous pedicle can course with the artery or can course 2 to 3 cm posteriorly. Both the artery and vein must be included within the confines of the flap.
Technical Considerations
To harvest the temporoparietal fascial flap, a vertical incision is made from the root of the helix to the superior temporal line if a wider flap is required. A V-shaped extension at the superior limit of the incision facilitates exposure. The superficial aspect of the flap must be dissected first in a plane just below the hair follicles. The deep side of the flap is a layer of loose areolar tissue that separates the temporoparietal fascia from the temporalis muscular fascia and allows straightforward dissection. The caudal extension of the pedicle dissection is limited by the location of the main trunk of the facial nerve.
Preoperative Considerations
Prior neck or parotid surgery, previous bicoronal incision, and external carotid embolization are relative contraindications to use of a temporoparietal fascial flap. Preoperative Doppler assessment of the patency and location of the pedicle is necessary.
Postoperative Management
Meticulous hemostasis with bipolar cautery that avoids injury to the hair follicles. The site can be primarily closed over suction drainage.
Muscle and Musculocutaneous Flaps
Rectus Abdominis Flap
Flap Description
The rectus abdominis flap has assumed an important role in head and neck reconstruction because it is easy to harvest, has a long vascular pedicle, and is extremely reliable. The area of skin harvested with a single rectus muscle encompasses a substantial portion of the abdomen and lower chest. One can include the entire muscle or only a small portion in the paraumbilical region, where the dominant perforators are located. For patients with excessive amounts of subcutaneous tissue in the anterior abdominal wall, a thinner flap can be harvested by means of skin grafting the muscle. This flap is used to reconstruct high-volume defects such as total glossectomy defects, skull base defects, and large cutaneous defects. At present, this flap is one of the best alternatives for total glossectomy defects because the rectus fascia can be sutured to the mandible to maintain the tongue mound in a position to obliterate the oral cavity. The rectus fascia can also be used to suspend the larynx. For patients with little subcutaneous tissue, the rectus abdominis flap can be used to manage moderate-volume defects such as hemiglossectomy and lateral temporal defects. In hemiglossectomy defects where the management of the reconstructed volume is critical to long-term function, a perforator-based rectus flap may be preferable. The disadvantages of this flap are poor color match to facial skin and a tendency to become ptotic. The versatility of the rectus abdominis flap, based on the deep inferior epigastric system of vessels, is shown in Fig. 162.5. The most commonly used configuration of the rectus flap is the transverse rectus abdominus myocutaneous (TRAM) flap, which is used for breast reconstruction. This configuration can be quite useful in the head and neck, particularly when large volumes of tissue are required in low-BMI patients or when cosmesis is an issue (for example, a young, low-BMI patient with a large tongue defect).
Neurovascular Pedicle
The rectus abdominis muscle has two dominant vascular pedicles, the deep superior epigastric artery and vein and the deep inferior epigastric artery and vein. The two systems connect above the umbilicus through a system of small-caliber vessels called choke vessels (17). When it is used for head and neck reconstruction, the rectus abdominis flap is based on the deep inferior epigastric system because of a larger pedicle size (the deep inferior epigastric artery is an average of 3 to 4 mm in diameter) and because the musculocutaneous perforators are direct branches of the deep inferior epigastric artery and vein and can supply a much larger territory of skin. The flap can be reinnervated
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with any of the lower six intercostal nerves, which supply segmental innervation to the rectus abdominis muscle and sensory supply to the overlying skin. The segmental sensory innervation of this flap makes it difficult to perform effective sensory reinnervation.
Figure 162.5 Versatility of the rectus abdominis flap. A: Vertical rectus flap. B: Middle and lower transverse rectus abdominis flaps. C: Thoracoumbilical rectus flap. D: Combined thoracoumbilical and vertical rectus flap. E: The abdominal wall with the left rectus muscle reflected inferiorly to expose the arcuate line. The layers of the rectus sheath are visible above and below the arcuate line.
Anatomic Variations
Few variations of the deep inferior epigastric artery and vein have been described. Sometimes the pedicle courses an unusually long distance along the lateral aspect of the muscle before taking a medial intramuscular route.
Potential Morbidity
Removal of the rectus abdominis on one side with a portion of the overlying fascia can weaken the anterior abdominal wall and predispose the patient to ventral herniation or midline bulge. Primary closure with a 0.0 monofilament Prolene on a taper needle will decrease the likelihood of a hernia.
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Technical Considerations
Understanding the anatomic characteristics of the fascial envelope is perhaps more critical for rectus abdominis flaps than it is for any other flap (Fig. 162.5E). Prevention of herniation depends on restoring the integrity of the abdominal wall through effective closure of the fascial layers. An important transition occurs in the posterior sheath at the arcuate line, which is approximately at the level of the anterior superior iliac spine. Above the arcuate line, the posterior sheath is composed of contributions from the aponeuroses of the transversus abdominis and internal oblique muscles. Below the arcuate line, the aponeurotic extensions of all three muscle layers contribute to the anterior rectus sheath. The posterior sheath is composed only of transversalis fascia. The posterior rectus sheath is sufficient to prevent abdominal herniation or bulge above the arcuate line, although most surgeons reinforce this closure with closure of the anterior rectus sheath. Below the arcuate line, the anterior sheath must be reapproximated to prevent abdominal herniation. The donor site can nearly always be closed primarily.
Preoperative Considerations
Preoperative assessment must include a careful history and physical examination of the abdomen to ensure that previous surgical procedures do not interfere with flap harvest. Rectus abdominis flaps may have to be avoided in patients who have undergone inguinal herniorrhaphy or appendectomy because there can be scarring in the region of pedicle dissection. A preoperative angiogram may be required in select patient where preexisting hernia or diastasis recti can complicate donor-site closure and militate against use of this flap. Vascular surgery, such as an aortofemoral bypass are contraindications to this flap.
Postoperative Management
Ileus can occur in the early postoperative period. Vigorous exercise that involves the abdomen is avoided for 6 weeks postoperatively.
Latissimus Dorsi Flap
Flap Description
A latissimus dorsi flap can be used for head and neck reconstruction as either a pedicled flap or a free flap. When the availability of a recipient vessel is in question, such as after radical neck dissection, this flap can be rotated onto the recipient site as a pedicled flap. When recipient vessels are available, the advantages of transferring the latissimus dorsi flap in a free-tissue transfer are as follows: There is more flexibility in flap positioning; the cutaneous portion of the flap can be centered over the vascular pedicle; the flap can be inset more superiorly, as for scalp reconstruction; and there is less risk of pedicle kinking. When the flap is transferred as muscle alone, the latissimus dorsi muscle atrophies to a thickness of approximately 4 mm. This makes it ideal for scalp reconstruction, but poor for large-volume defects. In the setting of massive scalp defects that require the entire muscle, the elevation of the latissimus can be staged. The staging procedure is performed by elevating the distal portion of the latissimus muscle and placing clips on five or six of the segmental, paravertebral, intercostal perforators that supply the second and third angiosome. The latissimus flap is definitively elevated 3 weeks later. For large-volume defects or large cutaneous neck defects, the latissimus dorsi muscle is transferred in a musculocutaneous flap. Attempts have been made to provide mobility of the mound in total glossectomy reconstruction by reinnervating the latissimus dorsi muscle with the hypoglossal nerve.
Neurovascular Pedicle
The thoracodorsal vessels arise from the subscapular vessels, which are branches of the third portion of the axillary artery and vein. The average diameter of the artery at its origin is 2.7 mm (range, 1.5 to 4.0 mm); the diameter of the vein is 3.4 mm (range, 1.5 to 4.5 mm); the average length of the pedicle is 9.3 cm (range, 6.0 to 16.5 cm). One of the many appealing features of this flap is the length of the vascular pedicle. The thoracodorsal nerve provides motor innervation to the latissimus dorsi muscle. The thoracodorsal nerve usually crosses the axillary vessels approximately 3 cm proximal to the subscapular artery and vein.
Anatomic Variations
The arterial supply and venous drainage of the latissimus dorsi flap have a number of anatomic variations, but none precludes elevation of the flap or compromises pedicle length. The anatomic variations involve independent origin of the thoracodorsal vein or the thoracodorsal artery from the axillary artery or vein. When the origins are separated, the subscapular artery arises proximally in the axilla by an average of 4.2 cm (18).
Potential Morbidity
Marginal flap necrosis can occur, but the cause is likely that the skin paddle was designed to be over the more distal aspect of the muscle (19). There is little morbidity except when a pectoralis muscle flap has been elevated on the ipsilateral side.
Technical Considerations
The patient must be carefully positioned on a beanbag in a semidecubitus position. With the patient in a 15-degree semidecubitus position, the flap can be harvested simultaneously with the resection of the primary lesion. The anterior border of the latissimus dorsi muscle is along a line between the midpoint of the axilla and a point midway between the anterior superior iliac spine and the posterior superior iliac spine. The thoracodorsal artery and vein enter the undersurface of the muscle 8 to 10 cm below the
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midpoint of the axilla. The vascular branches to the serratus anterior muscle are ligated during flap harvest. The surgeon can harvest either a limited amount of latissimus dorsi muscle under the skin or the entire muscle, depend-ing on reconstructive demands. It is possible to design a two-paddle perforator-based flap on the medial and lateral branches of the thoracodorsal vessels (Fig. 162.6). It is also possible to elevate a perforator-based latissimus flap based on the lateral branch of the thoracodorsal artery. The advantages are harvest of a small volume of latissimus muscle, preservation of the innervation of the latissimus muscle from the medial branch of the long thorassic nerve, and better control of the reconstructed volume, as there is little muscle present in the flap that will undergo atrophy, and presumably, there will be less deficit in shoulder function.
Figure 162.6 Left flank with the patient in the lateral decubitus position. The medial and lateral branches of the thoracodorsal artery are visible at the anterior edge of the muscle. The distal muscle can be used if a delay procedure that involves dividing the paraspinous perforators is performed 2 to 3 weeks before harvest. Additional pedicle length can be obtained if the circumflex scapular artery is divided.
Preoperative Considerations
Previous axillary lymph node dissection is a relative contraindication to the use of the latissimus dorsi flap. Preoperative angiography has been advocated in this setting to assess the patency of the thoracodorsal vessels.
Postoperative Management
Suction drains must be placed and left in place for several days postoperatively because of the high incidence of seroma that occurs with use of with the latissimus dorsi flap.
Gracilis Flap
Flap Description
This thin muscle flap from the medial thigh was introduced by Harii et al. (20), in 1976 and was subsequently popularized as a muscle-only flap for dynamic facial reanimation. The primary use of the gracilis muscle in the head and neck has been facial reanimation, in which the muscle is both revascularized and reinnervated to restore contractile activity. To restore synchronous mimetic movement when the proximal stump of the facial nerve is not available, a two-stage procedure is performed with a cross-face sural nerve graft at the initial stage. The Tinel sign is used to monitor the progression of axonal growth across the face, which usually takes 9 to 12 months after initial transfer. When the examination shows that the distal end of the sural graft has viable axons, the free muscle is transferred, revascularized, and reinnervated to the stump of the cross-face nerve graft. The advantages of this flap
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for facial reanimation are its neuromuscular structure, long vascular pedicle, and ease of dissection.
Neurovascular Pedicle
The dominant pedicle of the gracilis flap is the terminal branch of the adductor artery, which arises from the profunda femoris artery and runs a circuitous course between the adductor longus muscle anteriorly and the adductor brevis and magnus muscles posteriorly before entering the gracilis at the junction of the upper third and lower two thirds. The point of entrance of the vascular pedicle into the muscle is consistently between 8 and 10 cm inferior to the pubic tubercle. The artery to the gracilis is accompanied by two venae comitantes, which either join or drain separately into the profunda femoris vein. The caliber of the artery usually is 2 mm, and the caliber of the venae comitantes measures 1.5 to 2.5 mm. The motor supply to the gracilis muscle is the anterior branch of the obturator nerve, which enters the muscle in an oblique course approximately 2 to 3 cm cephalic to the entry point of the vascular pedicle (18).
Figure 162.7 The inner thigh of the left leg with a musculocutaneous gracilis flap dissected and only attached by its pedicle. The patient is positioned with the knee flexed and the hip externally rotated. With the knee flexed, the anterior edge of the gracilis muscle is marked with a line from the adductor tubercle to the tibial tubercle. The pedicle inserts on this line approximately 8 to 10 cm from the adductor tubercle.
Anatomic Variations
The main variability of the gracilis flap is the blood supply to the overlying skin rather than the vascular or nerve supply to the muscle. Yousif et al. (21) described variations in which there were no musculocutaneous perforators from the gracilis muscle, and most of the skin supply was from septocutaneous vessels or from the inferior branch of the superior external pudendal artery.
Technical Considerations
The branching pattern of the anterior division of the obturator nerve allows separation of the gracilis muscle into at least two functional muscular units. To minimize the bulk of muscle transferred, a single neuromuscular unit can be transferred that innervates the anterior portion of the muscle. The skin paddle, when needed, can be oriented longitudinally over the gracilis muscle. An alternative transverse orientation has been described. In either case, the cutaneous paddle must be centered over the dominant musculocutaneous perforator, which is 8 to 10 cm distal to the pubic tubercle (Fig. 162.7).
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Composite Free Flaps
Fibular Osteocutaneous Flap
Flap Description
The free fibular graft was first described by Taylor et al. in 1975 (22) for long bone replacement after trauma or cancer. Hidalgo (23) first described the free fibular flap for mandibular reconstruction in 1989. The fibula provides the longest possible segment of revascularized bone (25 cm) and has the thinnest associated skin paddle. Because of the small volume of the skin paddle, large-volume soft-tissue defects may require a second revascularized flap. Although the fibula can span nearly any mandibular defect, it lacks the diameter to reconstruct many dentulous mandibles. Unless adjunctive procedures, such as onlay bone grafting or vertical distraction osteogenesis, are performed, it lacks the cross-sectional diameter to reliably fix osseointegrated implants for implant bone prosthesis. The fibula is also useful for infrastructure (oral palate) maxillary reconstruction because of its long-pedicle, thin, associated skin paddle and small-caliber bone bone stock (24). The flap is amenable to a two-team approach because of the distance between the harvest site and the head and neck area.
Neurovascular Pedicle
The peroneal artery and vein provide the primary blood supply to the fibular osteocutaneous flap. Preoperative angiography or magnetic resonance angiography are recommended to ensure adequate arterial supply to the foot when the peroneal artery is sacrificed. Sensation can be variably restored when the lateral sural cutaneous nerve is used. The branches, once they supply the skin paddle, can be multiple, small, and tedious to dissect. The peroneal communicating branch can be harvested as a vascularized nerve graft to bridge the gap in the inferior alveolar to mental nerve to restore lower lip sensation.
Anatomic Variations
Much has been reported on the reliability of the blood supply to the skin (25). The perforators that supply the skin can course entirely through the posterior intermuscular septum as septocutaneous perforators or can travel as musculocutaneous perforators through the flexor hallucis longus and soleus muscles. A cuff of flexor hallucis longus and soleus should be included in the flap harvest (Fig. 162.8A). In 5% to 10% of cases, the blood supply to the skin paddle is inadequate.
Technical Considerations
When preoperative evaluation shows that either fibula is a suitable donor site, the donor site is chosen on the basis of ease of insetting. If the skin paddle is to be placed intraorally, the flap is harvested from the leg contralateral to the side of the inset and the recipient vessels in the neck. The flap is centered over the posterior intermuscular septum, which is anterior to the soleus muscle and posterior to the peroneus muscle (Fig. 162.8B and C). A Doppler flowmeter is used to identify cutaneous perforators along the posterior septum in the 15 to 25 cm range. Schusterman et al. determined that the greatest number of cutaneous perforators is present in this region (25). Shifting the skin paddle distally increases pedicle length. Flap elevation usually is performed with a thigh tourniquet inflated to 300 mm Hg. In the event that the skin paddle is inadequately perfused, a second soft-tissue donor site, which is usually the radial forearm site, is prepared.
Potential Morbidity
A variety of donor-site complications have been reported, including rolling out of the ankle, cold intolerance, and edema. Elevation and closure are important. The motor nerve to the lateral compartment will be exposed when the peroneal muscles are dissected from their origin on the fibula. It is not technically challenging to avoid this nerve, but knowledge of its location will facilitate indentification and preservation. When reapproximating the muscles after elevation of the fibula, it is important to not injure the nerve supply to the lateral compartment and to reapproximate the flexor hallucis at an anatomic length, so that it can effectively flex the toe. An 8-cm segment of fibula is preserved both proximally and distally to protect the common peroneal nerve proximally and to ensure stability of the ankle joint distally. A skin graft sometimes is needed for closure of the donor defect and is preferable to closure under excessive tension.
Preoperative Considerations
Assessment of the vasculature to the foot is essential before fibular transfer. MRI angiography has supplanted conventional angiography in most cases. A history of lower-extremity fracture, joint replacement, and bypass grafting directs the surgeon away from a particular extremity. Careful physical examination of the lower extremity for peripheral edema or non-healing ulcers is advisable in selection of the donor site because diseases related to peripheal vascular compromise and peripheral neuropathy such as diabetes may direct the surgeon to alternative donor sites.
Postoperative Management
Distal pulses in the foot are monitored as closely, as are the flap pulses to avoid the complication of vascular insufficiency to the foot, which can be caused by excessively tight closure or dressings. A prefabricated walking boot is fit in the operating room. It is left in position for 6 to 7 days to facilitate healing of the skin graft. Then the dressing is changed daily and the patient wears the boot for another 3 to 5 weeks to allow complete healing of the skin graft and to control pain. Ambulation is initiated with
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partial weight bearing on the third postoperative day, with the assistance of physical therapy and a walker. Full weight bearing with the assistance of a walker or a cane can take place on postoperative day five.
Figure 162.8 A: Cross-section of the leg shows the fibula flap is elevated and that both musculocutaneous and septocutaneous perforators course from the peroneal artery to the skin paddle. B: The flap is marked on the lateral aspect of the right leg. The cutaneous paddle is marked along the posterior intermuscular septum, which is visible when the foot is flexed and inverted. Dominant cutaneous perforators can be located with a Doppler flowmeter before the flap is elevated (10 to 25 cm distal to the fibular head). The presence of septocutaneous perforators can be confirmed after the cutaneous portion of the flap over the lateral compartment is elevated. C: Flap detached from the vascular pedicle with the soleus muscle still attached for illustrative purposes. The anterior approach to this flap is useful for obtaining a wide cuff of flexor hallucis and soleus muscles to encompass the musculocutaneous perforators.
Osteocutaneous and Osteomusculocutaneous Iliac Crest Flaps
Flap Description
The iliac crest flap can be harvested as an osseous, osseomyous, or an osseomyocutaneous flap. The pedicle is 5 to 6 cm long and can be lengthened if the segment of iliac crest is harvested at a more distal site. The original descriptions of the flap (22,26) were for mandibular reconstruction. Up to 16 cm of bone can be harvested. When harvested as an osseous flap, it is ideal for segmental mandibular defects with very limited soft-tissue component, such as those associated with odontogenic lesions. When harvested as a myosseous flap, it is ideal for segmental mandibular and maxillary defects with limited associated soft-tissue defects. The osseomyocutaneous is excellent for combined external skin defects. The skin paddle does not rotate easily into the oral cavity. If there is a large soft-tissue component combined with a segmental mandibular defect, the scapula flap or two flaps may be a better alternative. The iliac crest is also the best flap for retention of osseointegrated implants, as it has the largest cross-sectional area when compared to a fibula or scapula flap. The iliac crest is not the most commonly used osseous flap in oromandibular reconstruction because oral cavity defects usually involve intraoral soft tissue of the tongue, cheek, or palate and would require a second flap in addition to the iliac crest flap. The associated donor site morbidity is greater than either the fibula or the scapula.
Neurovascular Pedicle
The deep circumflex iliac artery arises from the lateral aspect of the external iliac artery, approximately 1 to 2 cm cephalic to the inguinal ligament. The ascending branch of the deep circumflex iliac artery supplies the internal oblique muscle in 80% of the cases. The remaining patients have multiple smaller branches supplying the internal oblique from the deep circumflex iliac artery (DCIA). This vascular pattern does not prevent use of the internal oblique muscle. The deep circumflex iliac vein usually is composed of two paired venae comitantes, which merge a variable distance lateral to the external iliac vein. The caliber of the deep circumflex iliac artery is 2 to 3 mm. That of the deep circumflex iliac vein ranges from 3 to 5 mm. There is no easily identifiable sensory component.
Potential Morbidity
Herniation of the abdominal wall can occur in the postoperative period. Meticulous, layered closure of the abdominal wall is essential to prevent ventral hernia. The transversus abdominis muscle is approximated to the cut edge of the iliacus muscle. This layer can be reinforced by means of placing drill holes into the cut edge of the iliac bone through which sutures are placed to reinforce the deep layer of closure. The next layer of closure approximates the external oblique muscle and aponeurosis to the tensor fascia lata and gluteus medius muscles. To decrease the likelihood of direct herniation, the internal oblique muscle is retained in a position inferior to the anterior superior iliac spine. This triangle of muscle is closed back to the lateral rectus sheath; 2.0 or 0.0 polypropylene is used, and a figure- of-eight suture is placed for each layer of this closure. The iliac crest osseomyocutaneous flap has robust blood supply to the bone and internal oblique muscle, but problems can occur with the blood supply to the skin. The skin is supplied by perforators from the deep circumflex iliac artery. The perforators can be easily sheared as they pass through all three layers of the abdominal wall.
Technical Considerations
The skin paddle is centered on an axis drawn from the anterior superior iliac spine to the inferior tip of the scapula (Fig. 162.9). Along this line, the zone of cutaneous perforators starts approximately 9 cm from the anterior superior iliac spine. The perforators are about 2.5 cm medial to the edge of the iliac crest. A generous cuff of external oblique, internal oblique, and transversus abdominis layers must be preserved as the cutaneous perforators course through these layers. This produces a bulky, relatively immobile skin paddle. The skin must not be rotated independently of the bone, to avoid twisting or stretching the cutaneous perforators.
Preoperative Considerations
Evidence of ventral herniation or previous inguinal herniorrhaphy can lead the surgeon to select an alternative donor site. If the patient has severe peripheral vascular disease, the surgeon needs to be sure that iliac artery bypass grafting has not been performed. If bypass grafting has not been performed, angiography of the deep circumflex iliac artery is performed to ensure vessel patency.
Postoperative Management
Progressive mobilization begins on the third postoperative day. On the fifth postoperative day, the patient can walk with a walker and progress to a cane and independent walking, as tolerated. Rigorous abdominal exercise is avoided for 3 months.
Fasciocutaneous and Osteofasciocutaneous Scapular and Parascapular Flaps
Flap Description
The unique features that make the scapular system of flaps so useful for head and neck reconstruction include the long length and caliber of the vascular pedicle; the abundant surface area of relatively thin skin that can be transferred; the separation of the soft-tissue and bone flaps,
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which provides the most freedom for three-dimensional insetting; and the ability to combine the scapular flap with the latissimus dorsi and the serratus anterior muscles, with or without overlying skin. This flexibility allows closure of complex orofacial defects (22). Up to 10 cm of bone, harvested from the lateral aspect of the scapula below the glenoid fossa, can be reliably transferred. The bone stock is variable and may be inadequate for the placement of osseointegrated implants for the purpose of mandibular rehabilitation. The fasciocutaneous flap is an excellent source of well-vascularized, moderately thin, hairless skin. The circumflex scapular artery has two cutaneous branches, which can supply two cutaneous flaps. The horizontally oriented scapular flap is based on the transverse cutaneous branch, and the vertically oriented parascapular flap is based on the descending cutaneous branch (27) (Fig. 162.10). The scapular flap is used most often to manage complex composite midfacial or oromandibular defects. A variation that is being used with increasing frequency is the scapular tip flap. This flap is a latissimis dorsi flap that is harvested with the scapular tip that is supplied by several branches from the thoracodorsal artery. This variation has a long vascular pedicle, supplies the entire scapular tip, and is useful for complex multisurfaced, high-volume midface and combined orbital reconstructions. This flap can be considered a latissimis osseomyocutaneous flap and can be combined with any variation of the scapular flap.
Figure 162.9 Vascular anatomic features of the iliac crest flap. The deep circumflex iliac artery (DCIA) courses in the superior aspect of the iliacus muscle. After it gives off the the ascending branch, the DCIA runs in the groove between the iliacus and transversus abdominis muscles before penetrating the transversus abdominis muscle and passing over the pelvic brim near the posterior superior iliac spine. The bone must be cut low enough to include the pedicle. The ascending branch can be identified on the undersurface of the internal oblique muscle and dissected proximally to help identify the DCIA. DCIV, Deep circumflex iliac vein.
Neurovascular Pedicle
The parent vessels of the scapular flap are the subscapular artery and vein, which arise from the third part of the axillary artery and vein. The circumflex scapular artery and vein emerge from the triangular space defined by the teres major and teres minor muscles and the long head of the triceps muscle. The circumflex scapular artery is accompanied by paired venae comitantes, which usually join the thoracodorsal vein before entering the axillary vein. The average diameter of the circumflex scapular artery at its takeoff from the subscapular artery is 4 mm. At its origin from the axillary artery, the subscapular artery has an average diameter of 6 mm. When the circumflex scapular artery is harvested at its takeoff from the subscapular vessels, the fasciocutaneous flap has a pedicle length of 4 to 6 cm. Although a maximum pedicle length of 11 to 14 cm has been extensively quoted in the literature, in pratice the length is much closer to 8 cm. The latissimus dorsi musculocutaneous flap, the scapular tip, and a portion of the serratus anterior muscle can be carried by the same vascular pedicle. When both the latissimus and scapular flaps are elevated, this flap can be referred to as a “mega” flap.
Anatomic Variations
There are five anatomic variations, but they are of little clinical consequence. The most common pattern is a single subscapular artery and a single subscapular vein supplying both the scapula and the latissimis flap. One of the variations is a duplicated circumflex artery. Of the remaining variations three, all are related to separate origins of the vein or artery for each of the two flaps.
Potential Morbidity
Morbidity of the brachial plexus can be caused by lateral decubitus positioning during flap harvest. If the patient is positioned fully decubitus, an axillary roll is needed, as is careful attention to arm positioning. Scapular osteotomy must stay 1 cm inferior to the glenoid fossa to avoid injury
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to the joint space. Harvest of the scapular osteocutaneous flap necessitates detachment of the teres major, teres minor, subscapularis, and infraspinatus, which can cause shoulder weakness and limited range of motion. These muscles must be meticulously reapproximated.
Figure 162.10 A: Vascular anatomic features of the left scapula. The subscapular artery sends the circumflex scapular branch through the triangular space to the scapular flap. The muscles that define the triangular space are palpated and marked preoperatively. The soft triangle is best approached by means of dissection over the teres major muscle at the lateral boarder of the scapula. Once the triangular space is located, the teres minor muscle can be retracted superiorly, and the pedicle can be dissected through the axillary space. B: The triangular space also can be located by means of marking the midpoint of the lateral aspect of the scapula. Three of the possible scapular paddles and their vascular supply are outlined. The deep branch is intimately associated with the lateral border of the scapula, which it supplies. If a bone flap is to be included, care is taken not to injure the deep branch after dissection of the cutaneous flaps.
Technical Considerations
To make two-team surgery easier, the patient can be placed in a 15-degree decubitus position with the assistance of a beanbag. Flap harvesting is technically more difficult than it is when the patient is in a 15-degree decubitus position, but the benefit is reduction in total operative time. A separate axillary incision can be helpful in dissecting the pedicle to the axillary artery and vein. If the bone of the scapula is elevated, the teres major, subscapularis, and latissimus dorsi muscles are reattached to the scapula with 2.0 or 0.0 polypropylene. Care is taken not to injure the motor nerve supply to the teres major muscle during flap elevation. Modified Kirchmeyer sutures can be useful for optimizing reapproximation of the cut end of the teres major muscle to the scapula.
Preoperative Considerations
Previous axillary node, dissection, shoulder reconstruction or prior shoulder dislocation is a contraindication to the use of fasciocutaneous and osteofasciocutaneous scapular and parascapular flaps.
Postoperative Management
If the scapular skin paddle is raised without bone, shoulder pain is minimized by immobilization for 3 or 4 days, followed by active range of motion exercises. If an osseocutaneous scapular flap has been raised, the shoulder is immobilized for 5 days to allow healing and pain resolution. A physical therapy program that includes active and passive range of motion is begun.
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Visceral Flaps
Jejunum
Flap Description
The free jejunal autograft has been successful in reconstruction of circumferential pharyngoesophageal defects (28). The diameter of the jejunum is a good match with the cervical esophagus and maintains an ideal mucosal surface for food bolus transit. In one series, (29) jejunal free-flap reconstruction of circumferential defects of the pharyngoesophagus was accomplished with low mortality (5%) and early functional restoration in terms of swallowing. The graft is harvested by a general surgeon in a simultaneous two-team approach.
Neurovascular Pedicle
Transilluminating the mesentery facilitates selection of a segment of intestine with sufficient arborization from a single mesenteric artery and vein to supply the graft (Fig. 162.11). The second arcade of the jejunum usually is best for pharyngeal reconstruction.
Potential Morbidity
Stricture of the upper or lower anastomosis occurs in about 10% of free jejunal transfers and responds well to dilation. This rate of stricture is lower than that encountered when tubed cutaneous flaps are used. Despite the lower stricture rate and relative ease of inset, the jejunum can have long-term functional problems. The peristalsis of the jejunum produces functional obstruction during swallowing, a wet voice among patients who speak by means of tracheoesophageal puncture, and dysgeusia from the succus entericus. The long-term functional problems can be nearly eliminated with postoperative radiation therapy. This reconstruction is optimal for a planned combined surgery followed by radiation therapy.
Figure 162.11 A: Segment of proximal jejunum of sufficient length supplied by a single arcade. B: The jejunum is shown as a segmental reconstruction of a total pharyngeal defect with a monitoring segment. The jejunum is inset under a minor degree of tension to reduce dysphagia.
Technical Considerations
A suture is placed at the proximal end of the graft at harvest to ensure isoperistaltic reconstruction of the pharyngoesophagus. Any redundancy of the jejunal segment is avoided to prevent dysphagia. The proximal end of the jejunum can be divided along the antimesenteric border to facilitate closure to the tongue base. The distal end of the jejunum is anastomosed in an end-to-end manner to the stump of cervical esophagus. To break up the circumferential scar, a lock-and-key type of closure can be made by means of vertical incision of the cervical esophagus. Postoperative monitoring is facilitated by exteriorizing a monitoring segment of the jejunum. This segment is based on the same mesenteric arcade as the rest of the flap (30). This segment can be observed for peristalsis and evaluated directly with a Doppler probe.
Preoperative Considerations
Extension of disease into the proximal thoracic esophagus is an absolute indication for esophagectomy and gastric pull-up. Several donor-site factors point the surgeon toward an alternative method of reconstruction. These include presence of ascites, chronic intestinal diseases such as Crohn disease, and previous extensive abdominal surgery or intraperitoneal sepsis. Patients with limited pulmonary reserve are at increased risk of morbidity after laparotomy.
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Postoperative Management
The external monitoring segment of jejunum is removed at the bedside on postoperative day seven by means of suture ligation of its mesentery.
Omentum and Gastroomentum
Flap Description
The greater omentum is a double layer of peritoneum that hangs like a sheet from its main attachments to the greater curvature of the stomach and transverse colon (Fig. 162.12). The blood supply to this structure arises from the right and left gastroepiploic vessels, which course in the cephalic edge of the omentum, where it attaches to the stomach (31). The omental free flap has a variety of uses in head and neck reconstruction, including coverage of large scalp defects, repair of extensive midfacial defects with coverage of split rib or calvarial grafts, management of osteoradionecrosis and osteomyelitis in the head and neck region, and facial contouring. Gastroomental free flaps can be used for oral or pharyngeal defects; omentum is used to provide carotid coverage. The surgeon must carefully weigh the functional and aesthetic benefits of this flap against the risks of an intra-abdominal procedure.
Neurovascular Pedicle
The right gastroepiploic artery is more favorable for supplying omental flaps. The diameter of the right gastroepiploic artery ranges from 1.5 to 3.0 mm.
Potential Morbidity
A wide range of intra-abdominal complications can occur after harvest of a gastroomental free flap. The most serious is gastric leak with peritonitis and intra-abdominal abscess formation. Gastric outlet obstruction can occur if the mucosal flap is too large or is placed too close to the pylorus.
Preoperative Considerations
A history of gastric outlet obstruction or peptic ulcer disease is a contraindication to this procedure.
Figure 162.12 Gastroomental flap completely elevated from the greater curvature of the stomach.
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Microvascular Reconstructive Approaches to Defects in the Head and Neck
When reviewing various reconstructive approaches in the literature, it can be difficult to interpret results within a study or compare results between studies because there is no universally adopted system for coding head and neck defects. An effort has been made to classify defects on the basis of loss of epithelium, bone, nerves, and supporting musculature (32).
Pharyngoesophageal Defects
Pharyngoesophageal defects are classified according to circumferential involvement (partial, near total, and total) and whether the esophagus or a large portion of the oropharynx was included in the resection. Also important in determining the optimal reconstruction is consideration of the mechanism of postoperative voice production (tracheoesophageal puncture versus electrolarynx) and the use of postoperative radiation therapy.
Partial pharyngoesophageal defects are defects in which approximately 50% of the pharynx has been sacrificed, such as one piriform fossa and 50% of the posterior pharyngeal wall, and primary closure cannot be performed without high risk of pharyngeal stenosis. Near-total pharyngoesophageal defects are defects in which only a thin strip of pharynx (1 cm) remains. Total pharyngeal defects are those in which there is complete absence of a segment of the pharyngoesophagus and is the defect in which free-tissue transfer has had the greatest impact.
Partial and near-total pharyngeal defects can be reconstructed with either pedicled regional flaps or free-tissue transfer. The following factors are taken into account to assist in decision making: (a) There must be adequate vascular access for a free-tissue transfer. (b) If a modified radical or radical neck dissection has been performed and carotid protection is believed beneficial, a pedicled regional flap such as a pectoralis or latissimus dorsi flap can be used so that the muscle can be laid over the great vessels. (c) If there is a total or near total defect and the regional flaps are thicker than 2 cm, use a free-tissue transfer that is thinner than 2 cm.
For total pharyngoesophageal defects, four types of reconstructions are considered; these include a gastric transposition (this is a pedicled flap), colon interposition, free-tissue jejunal transfer, and large free fasciocutaneous transfers such as radial forearm or an anterolateral thigh. The majority of total pharyngeal reconstructions can be performed with a free jejunal or free fascial free-tissue transfer. If the defect extends into the mediastinum, preoperative consultation with a thorasic surgeon and planning of a colon interposition flap is appropriate. Gastric transpositions are no longer the best reconstructive option because they do not remain well vascularized when extended up into the oropharynx and are associated with significant reflux.
The jejunal flap was once the technique most commonly used to reconstruct total pharyngoesophageal defects. The shortcomings are a wet voice, especially if the patient does not undergo postoperative radiation therapy, and dysphagia from autonomous peristalsis, halitosis, and difficulty with reconstructing more extensive oropharyngeal defects. Fasciocutaneous flaps (radial forearm, anterolateral thigh) are replacing the jejunum as the reconstructive option of choice. These flaps can provide better voice, less dysphagia, and less donor-site morbidity than does jejunum. There has been difficulty with stricture formation with radial forearm flaps. Insertion of a salivary bypass tube at the time of surgery nearly ameliorates this coplication (33).
In the situation of surgical salvage after failure of chemoradiation therapy, the fistula rate with primary hypopharyngeal closure is high. Use of fasciocutaneous free-tissue transfer for support of primary closure of hypopharyngeal defects decreased the fistula rate to 20% in a small case series (34). It seems reasonable to support primary hypopharyngeal closure with vascularized tissue to reduce wound complications and length of hospital stay.
Oral Cavity and Oropharyngeal Defects
In the oral cavity and oropharynx, microvascular reconstruction has improved function and reduced complications of the tongue and mandible (3). The sensate radial forearm flap has become the workhorse of low-volume, soft-tissue oral cavity reconstruction; the sensate lateral arm flap is an alternative for slightly larger volume defects. Reconstruction of associated mandibular bony defects can compromise soft-tissue reconstruction because the soft tissue associated with free revascularized bone flaps is not as versatile as a sensate radial forearm flap. When the functional results are likely to be compromised by use of the soft-tissue component of an osseous flap, two flaps can be used. A sensate soft-tissue flap and an osseous flap can be combined to optimize speech, swallowing, and cosmetic results. An example is an angle-to-angle mandibular defect combined with two-thirds anterior glossectomy. A fibular flap can be used for bony reconstruction, and a lateral arm flap or anterolateral thigh flap can be used for the glossectomy reconstruction. In the repair of larger soft-tissue defects that include the entire tongue, musculocutaneous flaps such as the rectus and latissimus dorsi flaps are used.
The principles of oral cavity reconstruction are to obtain watertight closure; maintain mobility; provide sensation, including cable grafting of segmentally resected sensory nerves; maintain the volume of the resected tissue; maintain oral competence; and prevent medically significant aspiration. The radial forearm flap is uniquely suited to reconstruction of the oral cavity when there is remaining functional tongue. It is a thin, supple flap of ample size
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to provide mobility. The antebrachial cutaneous nerve can be used to innervate the flap and provide cable grafts for the inferior alveolar or lingual nerves. De-epithelialized segments can be used to contour the flap to restore the original contour of the defect (35).
In total glossectomy defects, the muscle of a rectus or latissimus flap is used to reconstruct the floor of the mouth, and a large volume of subcutaneous tissue is made into a mound to allow contact between the flap and the remaining sensate mucosa in the oral cavity. If a laryngectomy has not been performed, the hyoid bone must be resuspended to the mandible to help prevent aspiration.
Complex full-thickness defects (defects that include oral mucosa in continuity with external skin) usually are encountered in conjunction with mandibular defects. These defects can be closed with an osteomusculocutaneous iliac crest flap, a multipaddled osteocutaneous scapula, or a combination of a soft-tissue flap and an osteocutaneous fibular flap.
Midfacial Defects
Midfacial defects traditionally have been managed with a prosthesis. Revascularized free-tissue transfer has been valuable in reconstructing the maxilla to maintain midfacial projection in the premaxillary, zygomatic, and infraorbital regions. It also has been useful in providing soft tissue to the cheek and orbit. The principles of midfacial reconstruction are to restore the contour and projection of the midface, to facilitate rehabilitation of an occlusal surface in the upper jaw, to provide oronasal separation, to close the orbit or provide a platform for prosthetic rehabilitation of the eye, and to maintain a functioning lacrimal system if the globe is intact. Use of a hard-palate obturator is an excellent approach to a maxillectomy defect, and that is limited to the ipsilateral secondary palate. When evaluating a patient for reconstruction of the midface, it is important to consider how a prosthesis can act in concert with free-tissue transfer to optimize the functional and aesthetic results.
It is helpful to classify defects involving the maxilla. These defects can be categorized first by dividing them into infrastructure (oral palate) and combined infrastructure and suprastructure defects (oral palate, maxillary buttresses, orbital rim, and orbit). Infrastructure (oral palate) defects are uncommon and can be approached with a wide variety of techniques. Combined infrastructure and suprastructure defects can be subdivided as follows: (a) maxillectomy with intact orbital rim, (b) maxillectomy including the infraorbital rim, (c) maxillectomy including the infraorbital rim and orbital contents, and (d) composite defects, which can include any of the other defects combined with facial skin. The principles to be addressed are midfacial projection in the area of the infraorbital rim, orbital floor support, oral-nasal separation, and a stable platform for mastication.
Maxillectomy defects with intact orbital rim are effectively reconstructed with an obturator. The obturator provides adequate oronasal separation and a stable platform for mastication. Maxillectomy defects including infraorbital rim are best reconstructed with free-tissue transfer, either alone or in concert with a prosthesis. An effective approach is an osseocutaneous forearm flap for infraorbital rim reconstruction and orbital floor support in combination with a prosthesis. An osseocutaneous flap, such as an iliac crest, fibular, or scapular flap, in combination with osseointegrated implants, has become a more frequently used approach to avoid an obturator.
Maxillectomy defects including the infraorbital rim and orbital contents are much larger volume defects. The principles to be addressed are the same as those for defects with an intact orbital rim with the additional issue of volume requirement in the orbit. A osseocutaneous scapular flap alone or an osseocutaneous radial forearm flap in combination with a maxillary prosthesis is used. Orbital prostheses usually are not accommodated in the primary reconstruction. A closed orbit is considered cosmetically superior (4).
The composite maxillectomy defect is complex. The osseocutaneous scapular flap has been most useful in the management of this defect. The osteocutaneous radial forearm is a distant second because of the small volume of bone stock and donor-site morbidity. The scapula has adequate bone stock to recontour most maxillary defects, the soft tissue can be positioned independently from the bone, and there is ample subcutaneous tissue to recontour the cheek and fill the orbit as needed. The scapular tip flap with its long pedicle, the latissimus for internal lining, and the scapula for external lining is a variation with a high level of utility.
Defects of the Base of the Skull
Microvascular reconstruction has been a key factor in facilitating skull-base surgery. The rectus flap has been used because of its bulk, long vascular pedicle (if the rectus muscle is included as part of the pedicle length), ability to make multiple skin islands by means of de-epithelialization, and ease of patient positioning and ability to perform primary closure at the donor site. The disadvantage of use of a rectus flap is poor color match and a tendency toward ptosis. These cosmetic limitations have decreased the use of the rectus flap in favor of osseocutaneous flaps. Bone defects associated with skull-base defects frequently are reconstructed with split calvarial bone or hydroxyapatite compounds. Any area of bony projection is reconstructed with vascularized bone if the patient has undergone or plans to undergo radiation therapy.
The principles of skull-base reconstruction are to support the dural closure (separation of the cranial cavity from the upper aerodigestive tract), provide carotid coverage, obliterate dead space, support nonvascularized bone reconstruction, and restore calvarial and facial contour. The defects can be anterior or lateral defects. Anterior defects that include the orbit and maxilla are best reconstructed
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with a large-volume flap such as an osseocutaneous scapular flap or a rectus flap as a distant second choice. Anterior defects with an intact maxilla that cannot be reconstructed with local flaps can be reconstructed with a scapular fasciocutaneous or a partially de-epithelialized radial forearm flap. Lateral skull-base defects are best reconstructed with a scapular flap, lateral arm flap, or thick anterolateral thigh flap. These flaps have better color match and a tendency not to become ptotic. Difficulties with patient positioning, however, have decreased the frequency of use of the scapular flap. As in the management of midfacial defects, careful consideration of the effect of free-tissue transfer on future prosthetic reconstruction is important to obtain the best functional and aesthetic results.
External Soft-Tissue Defects
Revascularized free-tissue transfer is useful in the management of massive cutaneous defects of the scalp or skin that cannot be reconstructed with local tissue or when reconstruction with a regional pedicled rotational flap gives suboptimal cosmetic results. The optimal flap for reconstruction is based on the site of the defect. For defects of the face and neck, the scapular flap and lateral arm flap are used because they have an adequate amount of subcutaneous tissue to allow contouring, and the contour is stable and does not become ptotic. The anterolateral thigh is being used more as an alternative. Further investigation is needed to determine its tendency to become ptotic. For scalp defects, the latissimus dorsi muscle with a split-thickness skin graft is used because it is thin, is tightly adherent to the skull, and easily allows fitting of a wig. Any calvarial defects are recontoured at primary reconstruction because any calvarial irregularity becomes obvious as the latissimus dorsi flap atrophies. For forehead defects, a radial forearm flap is used most often, although the color match is poor. The principles of reconstruction of large soft-tissue defects are to provide coverage of critical structures (large vessels, dura, or cranial nerves), restore the skeletal contour with split calvarial bone or hydroxyapatite paste, restore soft-tissue contour, allow fitting of a wig as appropriate, and obtain optimal color match.
References
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