Keywordsflap, graft, reconstruction, microsurgery, pedicle
The impact of major ablative surgery for cancer in the head and neck region can be devastating for the patient, aesthetically and often functionally. Reconstruction of oncologic defects is necessary to restore function and appearance in an effort to achieve total rehabilitation ( Fig. 17.1 ). Psychosocial, vocational, and emotional counseling may also be necessary for total recovery. Examples of aesthetic considerations include contour, appearance, and expression of the face. Restoration of oral competence also is necessary for patients who have undergone major surgery of the oral cavity and oropharynx. Functional concerns that warrant consideration include speech, mastication, and deglutition.
Ablative surgery to treat cancer leads to loss of soft tissue and bone ( Fig. 17.2 ). Soft tissue defects include missing epithelial (dermal or mucosal) lining as well as loss of volume of underlying soft tissues. Before any replacement of tissues takes place, the reconstructive surgeon must first prioritize the functional and aesthetic concerns, and then decide what tissue must be replaced or repaired. An assessment of available tissue donor sites then ensues. Ideally, like tissues should be replaced with like. For example, missing bone should be replaced with an osseous reconstruction; however, the need for bone reconstruction depends on the site and extent of bone resection and may not be possible or necessary in all instances. Special consideration is also required for reconstruction of resected nerves, blood vessels, and cartilage.
The surgical defect created by resection of either a primary or a metastatic tumor in the head and neck region can often be repaired by primary closure if the tissue loss is modest. However, if primary closure is not feasible, then viable tissue should be introduced to repair the surgical defect. Such tissue may be mobilized as a local or regional flap, transferring adjacent tissues from the head and neck region. Alternatively, reconstruction may require free tissue transfer from a distant donor site. Therefore flaps available for reconstruction of defects in the head and neck region may be classified as local, regional, or distant depending on their relationship to the area being reconstructed.
The viability of any flap depends on its type of blood supply. In general, axial flaps are more reliable because they are perfused by a predictable, named vascular pedicle. The width-to-length ratio of an axial flap may be as much as 1 : 5 or more depending on the particular flap chosen and its associated blood supply. In contrast, random flaps are less reliable because they are perfused by a smaller subdermal plexus of vessels. The narrower the base of the flap, the less likely a random pattern of circulation can support the tissue.
A better understanding of vascular anatomy, regional circulation, and the angiosome concept has resulted in the increase in availability and dependability of flaps with a wide range of applications in reconstruction of various defects. Flaps are most reliable when based upon a known vascular pedicle (i.e., axial pattern). As a result, muscle and myocutaneous flaps used for reconstruction are based on named vessels or their perforating branches, whether used as a pedicled regional flap or as a distant free flap. Microsurgery has evolved significantly, and the use of free flaps has become routine with the advent of operating microscopes and microsutures.
Special considerations are required for reconstructive surgery in each specific region of the head and neck. As such, these topics are approached individually.
Scalp, Skin, and Soft Tissues of the Face and Neck
The skin of the scalp, face, or neck can often be replaced easily with a skin graft or local flaps. However, when extirpation involves the underlying soft tissues with creation of surgical dead space, more complex reconstructive efforts with pedicled or free flaps are required. The use of regional muscle/myocutaneous flaps, such as the pectoralis major flap, is a common solution. Alternatively, free flaps applicable in these situations include the radial forearm, omentum, anterolateral thigh, latissimus dorsi, scapula, rectus abdominis, and groin flaps.
Paranasal Sinuses, Orbit, and Skull Base
Following major resections of the paranasal sinuses, orbit, or skull base, certain situations mandate reconstruction. For example, dura and intracranial contents should be separated from the nasal cavity after skull base surgery. Likewise, support of the globe should be planned whenever the orbital floor is resected. In addition, replacement of soft tissue bulk and overlying skin is the standard management of major three-dimensional composite defects. Repair of the skull base can be performed without bone by using galeal pericranial or a free flap. Reconstruction of the floor of the orbit may be accomplished with use of a free osteocutaneous flap or by combining a bone graft with a soft tissue free flap, depending on the circumstances. If alloplastic material such as titanium mesh is used to repair the floor of the orbit, then adequate soft tissue coverage should be provided to avoid exposure and extrusion of the alloplastic material. Preoperative planning requires consultation with a maxillofacial prosthodontist for appropriate prosthetic support. Consideration should be given to the use of computer-aided design/computer-assisted manufacturing (CAD-CAM) technology where complex bone reconstruction is required. Examples of these are mandible reconstruction and maxillary reconstruction. On occasion, rehabilitation is accomplished by prostheses alone instead of reconstructive surgery to achieve the desired result ( Fig. 17.3 and Fig. 17.4 ).
The goals of oral cavity reconstruction include both functional and aesthetic restoration. Major ablative surgery in the oral cavity may result in an oral cripple if appropriate efforts are not made to reconstruct the surgical defect and rehabilitate the oral cavity with restoration of removable or fixed implant-based dentation ( Fig. 17.5 ). The components of functional restoration are oral competency, clarity of speech, mobility of the tongue, mastication/occlusion, bolus transport, lip support, as well as prevention of nasal regurgitation and aspiration. Aesthetic considerations include restoration of facial height, soft tissue contour, chin prominence, and lip support.
Major ablative surgery for tumors of the oral cavity may result in loss of mucosa, submucosal soft tissues, underlying musculature, overlying skin, and/or adjacent bone. Small, superficial defects of the mucosa and underlying soft tissues in the oral cavity can in some cases be repaired by primary closure, a local mucosal/musculomucosal flap, or a split-thickness skin graft. More complex or extensive resections require tissue transfer with regional or distant flaps.
Resection of the upper alveolus may be satisfactorily reconstructed with a dental prosthesis. However, if permanent obliteration of the communication between the oral cavity and nasal cavity or maxillary antrum is needed, then a free flap is the best option. In reconstruction of the upper alveolus/palatal defects, CAD-CAM technology should be utilized if bone reconstruction is planned for accurate restoration of the contour of the face and alveolar arch. Resection of the lower alveolus with a marginal mandibulectomy does not typically require replacement of bone. However, dental rehabilitation is difficult, and implants are impossible following marginal mandibulectomy. On the other hand, a segmental mandibulectomy, requires reconstruction of the resected bone with a composite free flap. Here again, CAD-CAM technology is very applicable for accurate and expeditious reconstruction with a free bone flap.
The need for immediate reconstruction of pharyngeal defects cannot be overstated. The goal should be to restore the ability of the patient to resume oral alimentation as soon as possible after resection of the tumor. Reconstruction of the surface lining of the pharyngeal wall resulting from transoral excision of superficial mucosal lesions does not require any major reconstructive effort. In these cases, the surgical defect is left open to heal by secondary intention. On the other hand, full-thickness resection of the pharyngeal wall requires reconstruction with use of a regional myocutaneous flap or a free flap, keeping in mind that the eventual goal of such a reconstruction should be to restore deglutition without aspiration or airway obstruction.
When a laryngectomy is undertaken in addition to pharyngectomy, the reconstructive choices depend on whether there is partial or total loss of the hypopharyngeal circumference. Partial hypopharyngeal defects can be repaired with a pectoralis major myocutaneous flap, a supraclavicular fasciocutaneous flap, or a free flap. When circumferential resection of the hypopharynx is undertaken, the choice of flaps depends on the length of the resected segment. A short, circumferential hypopharyngectomy segment limited to the cervical region is reconstructed with either a free segment of jejunum or a tubed fasciocutaneous free flap. However, when the hypopharyngeal resection extends to include the cervical esophagus, then the options are colon interposition, free flap, or gastric pull up. Complication rates of up to 15% are reported following gastric transposition. Clearly, the goals of reconstructive surgery in this setting are to recreate a satisfactory alimentary conduit, prevent stricture formation, and avoid functional obstruction caused by redundant soft tissue.
Reconstruction With Skin Grafts
Small superficial defects of the mucosa or skin that are not amenable to repair by primary closure or rearrangement of adjacent tissue are considered for reconstruction with either a split-thickness or a full-thickness skin graft. Full-thickness skin grafts tend to have a better cosmetic appearance and less secondary contracture than split grafts; however, they are limited in size. Common full-thickness donor sites for head and neck defects include the retroauricular and supraclavicular areas. Split-thickness grafts are abundantly available but can undergo significant contracture, which can limit movement of functional areas such as the eyelids or tongue. Because split grafts are thinner, including only portions of the dermis, the metabolic requirement for healing is less than that for full-thickness grafts. As such, for poorly vascularized areas, split grafts are preferred. In general, for external skin coverage, skin grafts are best applied to the parts of the scalp or face that are relatively immobile. Thus skin grafts are most suitable for defects of the scalp, temple, nasal bridge, external ear, and postauricular region. A typical example is excision of a superficial melanoma from the skin of the bridge of the nose. Generally, surgical defects after excision of melanoma are not repaired immediately until the final paraffin section report from pathology shows clear margins. In the interim, the surgical defect is covered with hemostatic dressings, such as Surgicel ( Fig. 17.6 ). Cheek skin was advanced over the lateral portion of the defect, and a full-thickness skin graft from the posterior triangle of the neck was used to close the remaining defect ( Fig. 17.7 ). Occasionally, a full-thickness skin graft may be used, even on mobile parts of the face, if resection of a lesion leads only to skin loss that cannot be repaired in a more aesthetic manner ( Fig. 17.8 ).
Skin grafts similarly may be used in the oral cavity when the mucosal defect is either too large to heal by secondary intention or is likely to cause contracture and functional disability. This situation is particularly true in the case of superficial defects of the anterior floor of the mouth or buccal mucosa. When used in the oral cavity, it is quite common for portions of the skin graft to slough in the immediate postoperative period, but as long as the deeper layers of the skin graft remain viable, eventual epithelialization occurs with excellent functional results. Lesions suitable for skin graft repair in the oral cavity are shown in Figs. 17.9 through 17.12 .
Reconstruction With Cutaneous Flaps
Adjacent tissues may be elevated to reconstruct small surgical defects that cannot be repaired primarily. Also known as a local flap, adjacent tissues may be mucosal or cutaneous, depending on the location and the tissue requirements. Examples of mucosal flaps for intraoral repair are the tongue flap, the pharyngeal wall, and facial artery musculomucosal (FAMM) flap. However, because these flaps have a limited number of specific applications, surgeons are often unfamiliar with technical aspects of harvest, and these options may be perceived as unreliable. On the other hand, a palatal mucoperiosteal flap that derives its blood supply from the palatine artery is quite reliable in the repair of small through-and-through palatal defects or for the repair of a postsurgical oronasal fistula.
Many local cutaneous flaps are available for repair of surgical defects of the scalp and skin of the face and neck. Local flaps are preferable for repair of skin and soft tissue defects on the face because of superior color match and skin texture. The nasolabial flap is a commonly used axial local skin flap. Adjacent tissue transfer of skin flaps with a random blood supply (e.g., using cheek advancement, rhomboid, or bilobed flaps) is often useful for small defects of the face and neck when adjacent mobile skin is accessible (see several examples of local flaps in Chapter 3 ). A few regional fasciocutaneous flaps are available in the head and neck region for coverage of surgical defects that cannot be repaired by either primary closure or adjacent tissue transfer. Frequently used regional flaps include the deltopectoral, supraclavicular, cervical, and forehead flaps.
With the availability of free flaps, the popularity of regional cutaneous and myocutaneous flaps has declined, except for specific indications, such as the forehead flap for nasal reconstruction. Often the aesthetic and functional morbidity resulting from regional cutaneous flaps in head and neck reconstruction can be avoided by the use of free flaps. Regional flaps are easy to elevate, and the surgical defect can be reconstructed expeditiously. Consideration should be given to the availability of regional flaps before planning reconstruction with a free flap.
Regional Cutaneous Flaps
Regional cutaneous flaps are skin flaps that are available in the head and neck region for transfer from one area to another to cover a surgical defect that cannot be repaired by primary closure or by advancement of local tissues or local flaps. The most frequently used regional cutaneous flaps are the anterior or posterior cervical flap, the deltopectoral flap, the forehead flap, and the supraclavicular artery flap. The forehead flap is rarely used because of its significant donor site aesthetic morbidity. The blood supply to the forehead flap is axial, and the blood supply to the cervical flap is random. The blood supply to the deltopectoral flap is axial in its proximal part and random in its distal part. The blood supply to the supraclavicular artery island flap is axial from a branch of the transverse cervical artery.
The cervical flap is a regional flap with a random pattern blood supply. The width-to-length ratio therefore is 1 : 2, or at most 1 : 3, and thus, only a limited amount of skin is available. If a cervical flap of large width is used, a skin graft may be required to cover the donor site. The flap may be based superiorly or posteriorly and thus may be oriented vertically or transversely. When the skin of the anterior aspect of the neck is used, it is called the anterior cervical flap, and when the skin of the posterior aspect of the neck is used, it is called the posterior cervical flap or Mutter flap. The cervical flap generally is used to cover defects of the skin and soft tissues of the face and neck.
Reconstruction of a Preauricular Skin Defect.
The patient shown in Fig. 17.13 has a metastatic carcinoma in the left parotid region fungating through the skin with palpable cervical lymph nodes. The primary tumor, which was a squamous cell carcinoma of the skin of the left temple, was excised previously, and at this time, no evidence exists of recurrence at that site.
The surgical procedure planned is a modified neck dissection in conjunction with a subtotal parotidectomy and excision of the skin of the preauricular region to remove metastatic lymph nodes in a monobloc fashion. The incisions encompass the area of skin to be excised in conjunction with the outline of the transverse cervical flap and the remaining incision for completion of a neck dissection.
The cervical flap is elevated first, and then the remainder of the skin flaps are elevated. In Fig. 17.14 , the elevated cervical flap is shown, with its blood supply derived from the posterior aspect of the skin of the neck. Although this flap is random, its width-to-length ratio is almost 1 : 3. The distal part of the flap may be trimmed off and discarded to fit the surgical defect.
The cervical flap is now rotated cephalad ( Fig. 17.15 ). The tip of the flap is brought up to the upper margin of the skin defect in the preauricular region. The flap is appropriately trimmed to fit the surgical defect. The donor site defect in the upper part of the neck is closed primarily by mobilizing the skin of the cheek and the skin of the lower part of the neck.
Completed closure is shown in Fig. 17.16 . A satisfactory closure of the skin defect in the preauricular region is thus accomplished by the posteriorly based transverse cervical flap. Note the presence of a skin fold at the point of rotation of the cervical flap, producing a “dog ear.” In time this fold of skin usually flattens out and in most cases does not require revision.
The postoperative appearance of the patient is shown approximately 3 months following completion of postoperative radiation therapy ( Fig. 17.17 ). The flap not only provides excellent coverage but has a very satisfactory color match, giving an acceptable aesthetic appearance.
Another patient with a multifocal recurrent benign mixed tumor of the right parotid gland involving the overlying skin is shown in Fig. 17.18 . A superiorly based cervical flap was planned to correspond with the incisions for a parotidectomy with sacrifice of the overlying skin. The appearance of the patient 1 year following surgery shows excellent coverage of the skin defect in the parotid region ( Fig. 17.19 ).
Posterior Cervical Flap (Mutter Flap).
A superiorly based posterior cervical flap derives its blood supply from the occipital artery and the posterior auricular artery. Although these vessels are identifiable, the blood supply to the distal part of the flap is random.
In Fig. 17.20 , a schematic diagram of the posterior cervical flap and its anterior rotation is shown. The base of the flap should be kept wide enough to include the blood supply derived from the posterior auricular and the occipital arteries. However, the width-to-length ratio of this flap should not exceed 1 : 3. The donor site in the suprascapular region requires a split-thickness skin graft for coverage.
The patient shown in Fig. 17.21 has a recurrent metastatic carcinoma in the posterior aspect of the right side of the neck following previous neck dissection and radiotherapy. The recurrent cancer involves the skin of the neck and underlying subcutaneous soft tissues, although it is mobile over the deeper soft tissues. The area of skin excision and the planned flap are outlined ( Fig. 17.22 ). Note that the base of the flap extends from the mastoid process to the occiput. A wide three-dimensional excision of the recurrent tumor is performed with a generous margin of skin and underlying muscles from the floor of the posterior triangle of the neck as its deep margin. The flap is elevated and rotated anteriorly to cover the surgical defect, protecting the carotid vessels. The donor site in the suprascapular region is covered with a split-thickness skin graft.
The postoperative appearance approximately 2 weeks following surgery shows primary healing of the skin flap ( Fig. 17.23 ). The postoperative appearance of the patient 3 months following surgery shows excellent coverage of the surgical defect and an acceptable aesthetic result ( Fig. 17.24 ). This cervical flap has provided excellent coverage of the surgical defect with adequate soft tissues over the carotid vessels. The posterior cervical (Mutter) flap is a readily available regional flap for coverage of skin defects in the lateral aspect of the neck and the retromandibular area. However, it must be borne in mind that the flap has random pattern circulation in its distal part, and therefore its length is somewhat limited. It also requires a split-thickness skin graft for coverage of the donor site and thus produces some degree of aesthetic deformity.
Another patient with radionecrosis of the retromandibular skin and soft tissue is shown in Fig. 17.25 . The area of excision and outline of the flap are shown. Wide excision of the necrotic area is performed, and a superiorly based posterior cervical flap is rotated to cover the surgical defect. A small split-thickness skin graft is applied to the donor site ( Fig. 17.26 ). The appearance of the patient 18 months after surgery shows excellent healing with an acceptable aesthetic result ( Fig. 17.27 ).
The design of the posterior cervical fasciocutaneous flap, originally described by Mutter in 1842, has evolved due to more recent anatomic studies of the supraclavicular artery angiosome. The supraclavicular artery island (SCAI) flap is based on this vessel that originates from the transverse cervical artery and passes through the supraclavicular triangle (bounded by the superior border of the clavicle, the external jugular vein, and the posterior border of the sternocleidomastoid muscle). Its vascular territory extends from the lateral base of the neck to the anterior deltoid region.
The patient shown in Fig. 17.28 has recurrent melanoma in situ of the postauricular region. Following resection, the defect measures 7 by 11 cm ( Fig. 17.29 ). A supraclavicular artery island flap is mobilized up to the origin of its pedicle at the base of the neck ( Fig. 17.30 ) and rotated into the defect ( Fig. 17.31 ). The final result is shown in Fig. 17.32 . The postoperative appearance 1 year following surgery shows excellent reconstruction of the contour and an acceptable aesthetic outcome ( Fig. 17.33 ).
An elderly patient with a large mucosal and soft-tissue defect of the floor of the mouth and posterior tongue is shown in Fig. 17.34 following resection and neck dissection. A SCAI flap was raised to repair the intraoral defect, as shown in Fig. 17.35 . The flap is tunneled and reaches the defect without tension ( Fig. 17.36 ). The flap is inset, showing the anterior aspect of the cutaneous island replacing the missing oral mucosa ( Fig. 17.37 ).
These two examples demonstrate different applications of the supraclavicular flap. In one instance the skin paddle is deepithelialized, creating an island to repair a small intraoral defect. In the other example, the entire skin paddle is preserved to resurface larger areas of missing skin.
In the past, the medially based deltopectoral fasciocutaneous flap was considered a workhorse for reconstruction of oropharyngeal and pharyngoesophageal defects. The flap derives its primary blood supply from the perforating branches of the internal mammary artery through the second, third, and fourth intercostal spaces. The proximal part of the flap therefore has an axial blood supply; however, the distal third is random, with perfusion relying upon the subdermal plexus ( Fig. 17.38 ). With better understanding of perforator anatomy, the deltopectoral flap has been revisited as the internal mammary artery perforator (IMAP) flap. Advantages of this variant include harvest of a smaller flap enabling primary donor site closure and greater arc of rotation because of the flap’s narrow base around a single perforator.
The deltopectoral flap was popularized by Bakamjian in the mid-1960s and remained popular for reconstruction of oropharyngeal and hypopharyngeal defects. However, because of the unreliable blood supply to the distal third of the flap, high complication rate, and need for multiple stages, the flap is no longer routinely used for oral and pharyngeal defects. In contrast, the deltopectoral flap remains an excellent means of reconstruction for resurfacing skin defects in the cervical region. Therefore the deltopectoral flap should remain in the armamentarium of the head and neck reconstructive surgeon, particularly for skin and soft-tissue defects involving the lower two-thirds of the cervical region. The deltopectoral flap is an ideal choice for coverage of the skin defects of the lateral aspect of the neck. The patient shown in Fig. 17.39 was previously treated with radiation to the neck. He underwent salvage neck dissection for persistent disease and developed skin necrosis with exposure of the carotid artery. The area of compromised skin covers nearly the entire lateral aspect of the neck. The outline of the deltopectoral flap merges with the lower end of the skin excision of the neck ( Fig. 17.40 ). The skin is excised, and all necrotic tissue is debrided ( Fig. 17.41 ). The flap is elevated, preserving its blood supply from the perforating branches of the internal mammary artery ( Fig. 17.42 ). The flap is rotated cephalad to cover the skin defect in the neck. This is a tension-free closure ( Fig. 17.43 ). The donor site overlying the deltoid muscle is covered with a split-thickness skin graft ( Fig. 17.44 ). Excellent coverage of healthy skin and soft tissues is achieved in this manner.
Another patient with a melanoma of the skin of the lower part of the neck is shown in Fig. 17.45 . Wide excision of the skin and underlying soft tissues resulted in a full-thickness defect measuring 9 by 13 cm. This was repaired with a medially based deltopectoral flap ( Fig. 17.46 ). A portion of the flap donor site required skin graft. Therefore the deltopectoral flap should remain in the armamentarium of the head and neck reconstructive surgeon, particularly for skin and soft-tissue defects involving the lower two-thirds of the cervical region.
Reconstruction With Myocutaneous Flaps
The description of myocutaneous circulation in the mid-1970s led to the development of several regional pedicled myocutaneous flaps that provide an excellent means of reconstruction of defects in the head and neck region, particularly when free tissue transfer capabilities are not available. The pectoralis major, the trapezius, and the latissimus dorsi myocutaneous flaps have been described for reconstruction in the head and neck region.
The pectoralis major myocutaneous (PMMC) flap is readily available for reconstruction of a variety of defects in the head and neck region.
The advantages of this flap include:
Technical ease of flap elevation
Generous amount of skin and soft tissue available
Consistent and reliable blood supply
Arc of rotation that is adequate for most oropharyngeal and skin and soft tissue defects up to the skull base
Ability to provide both internal and external lining (using two skin islands on the same muscle)
Utility as a muscle flap alone to buttress the pharyngeal suture line in patients undergoing salvage surgery after radiotherapy
Robust muscular component of the flap to protect exposed neck vessels
Ease of primary closure at the donor site
The disadvantages of the PMMC flap are:
It is bulky, especially in women with large breasts. The bulkiness of the flap in some cases limits its use for oral cavity reconstruction.
When used for oropharynx or floor of mouth reconstruction, the flap tends to dehisce due to the downward pull of the tissues
Inadequate arc of rotation for upper facial and maxillary defects
Donor site aesthetic concerns due to distorted symmetry
Unreliability of the skin on the distal part of the flap
The anatomic features of the pectoralis major myocutaneous flap are depicted in Fig. 17.47 . The blood supply of the pectoralis major myocutaneous flap is derived from the descending branch of the thoracoacromial artery, as shown on the left-hand side in the diagram. This artery runs directly on the undersurface of the pectoralis major muscle. The thoracoacromial artery originates from the subclavian artery at about the midclavicular point and runs directly caudad toward the nipple. Thus a line joining the midclavicular point to the nipple is recommended for the surface marking of the vessel. One or two veins usually accompany this artery. The flap can be raised in a variety of different configurations, depending on the surgical defect to be reconstructed. Thus the size of the skin island is variable, and similarly, the extent of the transposed muscle is also variable ( Fig. 17.48 ).
The technical details of flap elevation are discussed here. The outline of the flap is drawn on the skin ( Fig. 17.49 ). The lined area on the distal part of the flap may be discarded so as to match the shape of the defect. The length and width of the myocutaneous flap skin island and the length of its pedicle are determined by the site, size, and shape of the surgical defect. The pivot point of flap rotation corresponds roughly to the midclavicular point. A tape is used to measure the distance from this point up to the most distal portion of the surgical defect. This measurement is the distance from the midclavicular point up to the distal tip of the flap, which is marked. The approximate width and length of the flap then are estimated to match the defect, and the proposed flap is drawn on the skin of the anterior chest wall. Elevation of the flap should never occur before resection of the tumor and assessment of the surgical defect. The exact dimensions and configuration of the defect are confirmed to match the outline of the flap. Any adjustments to the length and width of the skin island of the myocutaneous flap, or the length of its pedicle, are performed at this point, before the flap is elevated.
Elevation of the flap begins on its medial aspect first. The skin incision is deepened through the subcutaneous tissues and fat circumferentially around the skin island until the underlying pectoralis major muscle is visualized. From the proximal end of the skin island, an additional incision is taken up to the midclavicular point. The lateral and medial skin edges are elevated over the pectoralis to expose a generous area of muscle to be transferred with the myocutaneous flap ( Fig. 17.50 ).
The fingers of one hand are now inserted deep to the pectoralis major muscle in a plane between the pectoralis major and pectoralis minor muscles, as shown in Fig. 17.51 . Because this plane contains only loose areolar tissue, the pectoralis major is easily separated from the pectoralis minor muscle and the ribs. The pectoral nerve that travels between the pectoralis minor and pectoralis major muscles in this plane is divided. The undersurface of the pectoralis major muscle is mobilized up to the clavicle, freeing up its entire posterior surface. This maneuver enables identification of the thoracoacromial vessels at about the midclavicular point. Using a serrated scissors, the pectoral muscle is divided medial and lateral to the vascular pedicle up to the clavicle ( Fig. 17.52 ). The isolated portion of the myocutaneous flap is now lifted to expose the undersurface of the pectoralis major muscle to show the vascular pedicle, which is viewed from the right-hand side of the patient in Fig. 17.53 . A close-up view of the vascular pedicle is shown in Fig. 17.54 .
A 4-cm strip of muscle is routinely maintained over the pedicle. During this phase of the operation, several perforating branches of the internal mammary artery will be encountered, which are ligated and divided. The pedicle, the muscle, and the myocutaneous component of the whole flap fully mobilized are shown in Fig. 17.55 . If the skin surface of the flap is to be used for pharyngeal repair, then the flap is flipped 180 degrees. On the other hand, if the skin is to be used for surface coverage, then the flap is rotated radially up to 90 degrees. After the flap is rotated, the venous component of the vascular pedicle must be checked to ensure that blood is flowing freely through the veins. If the veins are twisted and collapsed or the skin paddle appears congested, the pedicle should be released further to address pedicle kinking.