Chapter 42: Cheek Reconstruction

The subcutaneous musculoaponeurotic system (SMAS) underlies the subcutaneous tissue and skin of the cheek to invest the facial muscles and is continuous superiorly with the superficial temporal fascia (not the deep) and inferiorly with the platysma. Motor nerves to the facial mimetic muscles run deep to the SMAS while sensory ones run superficial to it. The face has multiple superficial fat compartments that include the inferior orbital, nasolabial, medial, and lateral temporal zones. The cheek receives its blood supply from multiple vessels arising from branches of the external carotid artery. These include the facial artery, transverse facial artery (from superficial temporal artery), and infraorbital artery of the maxillary artery. Sensory innervation to the cheek is not only from the maxillary and mandibular divisions of the trigeminal nerve, but also from the cervical plexus.1,2

2. Mehara B. Cheek reconstruction. In: Grabb and Smith’s Plastic Surgery. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2007 The sensory innervation to the cheek arises from the second and third divisions of the trigeminal nerve and the cervical plexus. The only nerve listed above from the second (maxillary) division of the trigeminal nerve is the zygomaticofacial nerve which is the terminal branch of the zygomatic nerve. It passes along the inferolateral part of the bony orbit and exits the orbit at the zygomaticofacial foramen in the zygoma, then perforates the orbicularis oculi muscle to reach the malar skin which it innervates. The inferior orbital nerve is the other key branch of the maxillary division that innervates the skin of the cheek, nose, and upper lip. The buccal, mental, and auriculotemporal nerves are all branches of the mandibular division of the trigeminal nerve. The buccal nerve supplies the buccal mucosa, skin, and the second and third upper molars; the mental nerve supplies the lower cheek and chin, while the auriculotemporal nerve supplies the temple and upper part of the ear. The great auricular nerve is a branch of the cervical plexus C2/3 and supplies the preauricular region and the lower parts of the ear (Fig. 42.1).1–3 Fig. 42.1 Sensory nerve distribution to the face. Auriculotemporal nerve (CN V3) Zygomaticotemporal nerve (CN V2) Zygomaticofacial nerve (CN V2) Infraorbital nerve (CN V2) Buccal nerve (CN V3) Great auricular nerve (C2, C3) Mental nerve (CN V3) Transverse cervical nerve (C2, C3) External nasal nerve Infratrochlear nerve Lacrimal nerve Supratrochlear nerve Supraorbital nerve (CN V1) V1 V2 V3

3. Mehara B. Cheek reconstruction. In: Grabb and Smith’s Plastic Surgery. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2007 The cheek is the largest aesthetic unit of the face and has four borders, namely, upper, lower, medial, and lateral. The upper border is delineated by a line from the helical root to the lateral canthus which continues as the inferior orbital rim as far as the medial canthus. This border is also delineated by the zygomatic arch and inferior orbital rim. The lower border is delineated by the lower border of the mandible and passes from the mandibular angle to the chin. The posterior border is the junction between the pinna and the cheek, that is, the preauricular crease, passing from the zygomatic arch to the mandibular angle. The anterior or medial border is delineated by the nasojugal and nasolabial folds passing into the labiomandibular crease. The inferior and posterior borders therefore converge at the angle of the mandible. The cheek can be further subdivided into three or four overlapping subunits. These are the preauricular, infraorbital, and buccomandibular (Fig. 42.2). This has clinical relevance when reconstructing cheek defects. The main considerations are that the preauricular region overlies the parotid and facial nerve, the infraorbital region represents the junction between the lower eyelid and cheek, and the buccomandibular region includes the external mobile skin of the cheek and the internal lining of the oral cavity. From a reconstructive perspective, defects of the buccomandibular region may be full thickness and require more complex three-dimensional reconstructions with flaps or grafts for both internal and external lining. In contrast, the other areas are most often partial-thickness defects that can be managed with single layer flaps or grafts for external resurfacing.1–5

Smaller cheek defects are generally best closed directly or with local flaps, particularly when they are deep, as in this case. This is because they provide superior color and texture match with avoidance of a contour defect. Inferiorly based flaps can reduce trap-door effect and postoperative edema because they facilitate flap drainage with gravity.1,2 When skin grafts are used, full thickness is preferable to split thickness as there is less secondary contraction and the color match is superior. The optimal full-thickness graft location is probably the contralateral preauricular site as the color and texture match are good and the donor site may be well hidden at the junction of the ear and the cheek. Other sites are postauricular and supraclavicular. The location of this defect is not ideally suited to the cervicofacial flap and use of this flap is excessive for defects of this size, given the more conservative options available. Fig. 42.2 Subunits of the cheek. (1. medial or infraorbital unit; 2. zygomatic unit; 3. buccomandibular unit; 4. lateral or preauricular unit)

5. Başağaoğlu B, Bhadkamkar M, Hollier P, Reece E. Approach to reconstruction of cheek defects. Semin Plast Surg 2018;32(2):84–89

correct? When insetting a cervicofacial flap, placement of anchor sutures to the periosteum of the lateral orbital wall and zygomatic arch is very important to minimize subsequent development of ectropion. This approach may also be combined with a lateral canthopexy if inadequate lower eyelid support remains a concern. A preauricular incision, as used in a face lift, can be ideal in some patients. However, in males the sideburn will be moved medially if this incision is performed. Therefore, it is preferable to place an incision along the medial aspect of the sideburn only passing to the preauricular sulcus beneath the tip of the sideburn. Furthermore, cervicofacial flaps can be either anteriorly or posteriorly based. The incisions will differ between the two. The incision for an anteriorly based flap starts at the superolateral aspect of the defect and is carried laterally across the lower eyelid and zygomatic arch then continued into the preauricular crease. In contrast, a posteriorly based flap starts at the medial aspect of the defect and continues along the nose–cheek junction, the nasolabial fold, and labiomental crease. The anteriorly based cervicofacial flap must be designed to extend above the zygomatic arch to ensure sufficient reach, as it has to both rotate and advance. The flap must be extensively undermined (often as far as the clavicle, when reconstructing large defects) to maximize reach and minimize tension during closure. The level of dissection should initially be in the subcutaneous plane, but should be subplatysmal in the neck to ensure adequate vascular supply to the flap. The marginal mandibular nerve must be carefully preserved during the dissection.1,2

Tissue expansion offers the best color and texture match for reconstructing large defects of the cheek and multiple custom-made expanders may be needed. When selecting the expander device, the defect area must be considered. The expander base area should be 2.5–3 times the defect area. An expander for a flap over a curved area should be inflated to 2.5–3 times the defect width and inflated 2–3.5 times the width of a flat defect. Size and volume also need to be chosen so that when fully inflated, it will not distort important adjacent structures such as the eyelid or ear. Intraoperative filling may help to prevent hematoma and seroma formation. However, a balance is needed to prevent excessive tension during primary closure that will increase the risk of wound breakdown and subsequent extrusion. Formal expansion should begin 2 weeks after the primary surgery and then continue on a weekly basis. Overexpansion by 30–50% is advised in the cheek area to overcome flap contraction. The capsule is a very vascular structure and should remain within the local tissue flaps that are used for closure. If the capsule is tight, it can be scored (capsulotomy) to allow more flap advancement but capsulectomy should not be performed.1

Intraoral defects involving the cheek can be reconstructed using a number of different local flaps. Many of these receive blood supply from the facial artery. The hemi-tongue flap, however, is based on the lingual artery. It has many varied uses including resurfacing the buccal lining, and reconstructing the palate, the lips, and the floor of mouth.1 Flaps based on the facial artery include the facial artery myomucosal flap (FAMM), the submental artery flap (from branches passing through the submandibular gland), and the random pattern nasolabial flap (predominantly from the angular branch of the facial artery).2–4 The buccal fat pad is based on a subcapsular plexus formed by both the facial artery and the internal maxillary artery and has good reported outcomes in reconstructing smaller intraoral defects.5 The nasolabial region also receives blood supply from the infraorbital artery which is derived from the maxillary artery; however, this only supplies the superiorly based flap.

The defect created in this reconstruction is likely to be 5 by 6 cm in diameter and will require importation of distant soft tissue. Bone will not be required unless a segmental mandibular resection is planned. The pectoralis major can be tunneled under the neck dissection flaps and used for intraoral reconstruction, but reach will be difficult and the donor site is poor for young female patients. It tends to be used as a salvage flap in elderly patients, where free tissue transfer is contraindicated. Local flaps such as the tongue, FAMM, and buccal fat pads can be useful for smaller intraoral defects, and in this case may be sacrificed during tumor resection. Either free radial forearm or free anterolateral thigh (ALT) flaps can be used in this case. An ALT flap is favorable because of its hidden scarring. One problem with ALT flaps for intraoral reconstruction is that they can be bulky, causing functional difficulties with speech and eating. In a patient with a low BMI, this should not be a major problem. Other reconstructive options for this patient include the scapula, parascapular, lateral arm, or groin flaps.1–4

The blood supply to the flaps listed is as follows: • Pectoralis major: Internal mammary perforators, thoracoacromial vessels, and lateral thoracic vessels • Deltopectoral: Internal mammary perforators • Trapezius: Transverse cervical, dorsal scapular, and posterior intercostal vessels • Sternocleidomastoid: − Upper: Occipital artery − Middle: Superior thyroid or external carotid artery − Lower: Suprascapular artery from the transverse cervical artery • Latissimus dorsi: Thoracodorsal and posterior intercostal perforators This defect can be reconstructed with a deltopectoral, pectoralis major, trapezius, or latissimus dorsi flap.1 The sternocleidomastoid is unsuitable for this reconstruction because of its segmental blood supply and small size.2,3 The pectoralis major muscle provides a reliable flap for reconstruction of the head and neck region. It can be muscle only or muscle and skin. The donor site can usually be closed directly by undermining adjacent tissue and rotating/advancing this into the donor defect. It will however distort the breast, particularly in women. The pedicle can be identified as it passes between the sternal and clavicular heads of the muscle, just below the clavicle. It is possible to dissect close to the vessel in this area in order to minimize bulk at the pivot point. The flap is then passed under a subcutaneous tunnel into the neck. The deltopectoral flap is usually reserved as a lifeboat flap and can be elevated and replaced during a pectoralis major flap harvest. The trapezius flap is particularly useful for posterior defects over the upper cervical spine as it has a reliable blood supply and easily reaches to provide muscle cover over the spinous processes. The donor site can usually be closed directly. A fasciocutaneous flap based on the transverse cervical vessels can be useful for head and neck reconstruction in both intraoral and skin defects. This is termed a supraclavicular artery perforator (a-SAP) flap.4 The latissimus dorsi is not commonly used for head and neck reconstruction, although it may be incorporated into a free scapula flap when bone and soft tissue reconstruction is required (Fig. 42.4). Fig. 42.4 Pectoralis major flap with two skin paddles: one for the intraoral defect and one for the cutaneous defect. (Although this was a common flap in years past, it is now mostly used as a salvage option.) Defect of oral lining, cheek subcutaneous tissue, and artery Pectoralis muscle released from humerus Skin paddle A to fill skin defect Skin paddle B to re-create intraoral lining Pectoralis muscle released from chest Pectoralis muscle is flipped 180° after release A A B B Skin paddle A is flipped to fill skin surface Skin paddle B to fill intraoral lining

A standard of care in free tissue transfer reconstruction is to preempt the need for revision procedures. Therefore, it is important to discuss this early with patients during consultations prior to undergoing the first part of the reconstructive process. In cases where there is already much other information to absorb, there remains a high chance that patients will not retain all of the information and so additional written information leaflets can be useful. The need for potential revision applies not only to facial reconstruction, but more broadly in many anatomic areas. The key is to ensure that patients are well informed and have realistic expectations at each stage of their care pathway. The precise nature of and timing for revision will depend on each patient’s individualized case. However, the principle is generally that revision is left for at least 6 months to allow the soft tissues to soften and mature. In addition, beyond this time point, most soft tissue flaps will have generated additional useful blood supply from the surrounding tissues and will no longer be purely reliant upon the vascular pedicle for their blood supply. This means that revisions can be more reliably and robustly undertaken. Common revisions include re-insetting and revising the skin elements of a flap, thinning bulky flaps such as the anterolateral thigh (ALT) with liposuction, and releasing scar tethering or adjusting tissue advancements particularly around the eye, nose, or mouth. Bony revision is less commonly needed as bone reconstruction in the cheek is less often needed anyway and bone inset is usually quite reliable and adequately placed in the first procedure. Contour defects can be managed with either permanent or nonpermanent fillers but are certainly not required in most cases.1