Relaxed Skin Tension Lines

As discussed in Chapters 1 and 2, the relaxed skin tension lines (RSTL) generally run inferiorly and posteriorly over the surface of the cheek. If possible scars should be placed along these lines, particularly because these lines eventuate into wrinkle lines. Also scars are best placed in the lines and grooves of the periphery of the cheek in the cosmetic unit junctions, such as the preauricular fold, the melolabial fold, and the nasofacial angle. It should be noted, however, that flap incisions rarely spread when placed perpendicular to the relaxed skin tension lines. The reason for this is that in the cheek, although the inherent pull in the direction of the RSTL is more than the pull in the direction perpendicular to the RSTL, it is not very much more.

Surface Anatomy

The boundaries of the cheek are the preauricular crease, the superior border of the zygomatic arch and malar eminence, the inferior orbital rim, the nasofacial angle, the melolabial crease, and the inferior border of the mandible. The cheek may be roughly divided into seven somewhat overlapping and poorly demarcated subunit areas for the purpose of discussion. These seven areas include the following: medial, anterior (maxillary), infraorbital, zygomatic, buccal, preauricular, and mandibular. In each of these areas some flap types are more preferable than others. Many repairs in the cheek cross over and include more than one of these subunits. In some peripheral borders on the cheek, for instance the cheek and eyelid boundary, the border is best not transgressed by a single flap, but rather two flaps, one from the upper eyelid and one from the cheek so as to reestablish the boundary between the cheek and eyelid zones.¹

Repairs on the face may be regional (eg, the whole cheek) as emphasized by Gonzalez-Ulloa² or local (small flaps on only a portion of the cheek). The subunit principle applied by Burget and Menick³ to the nose is not as critical on the cheek because the subunits are less distinct. The only defining grooves are at the periphery of the cheek along the cosmetic unit junctions.

The cheek is not a flat surface, but is concave medially as it extends into the nasofacial sulcus; it is convex over the malar eminence. Only in the lateral cheek and preauricular area is the cheek flat. This uneven topography is important for the surgeon to be mindful of as cheek reconstruction is three-dimensional.

Abundant loose skin exists on the cheeks for flap repairs. This abundant tissue is usually found inferior to defects to be reconstructed. With age, cheek skin begins to sag and thus more loose tissue becomes available for repairs. However, in the elderly who have had a facelift procedure or in the young, this normally abundant tissue is generally not as plentiful. Additionally, if prior surgery has been done on the cheek, the underlying anatomy may have been altered and tissue may not move normally.

Skin Texture

Skin surface characteristics may vary enormously on the cheek from individual to individual and also within the cheek on the same individual. In patients with very oily skin and patulous pores it may be more difficult to get a good cosmetic result than in patients with smooth non-oily skin. Elderly patients with a plethora of skin laxity wrinkles will be easier to reconstruct than the young who have greater elastic skin recoil and no wrinkles. Wrinkles afford camouflage for linear, arciform, and flap incision lines. Because of the unique texture of cheek skin, skin grafts in this location generally provide a poor color and texture match. Skin grafts on the cheek appear as patches and should be avoided if possible. The texture of cheek skin may also vary from one cheek region to another. The beard area on the male needs to be kept in mind. The wrong skin in the wrong place may lead to a less than optimal cosmetic result.

Subcutaneous Anatomy

Beneath cheek skin lies an investing fibrous layer, the submuscular aponeurotic system (SMAS). This layer lies between and is attached to the dermis above and the muscles below. Inferiorly SMAS is continuous with the platysma muscle.⁴ Deep to the SMAS lies the parotid gland and its duct, facial nerve branches, and the superficial muscles of facial expression. All these muscles are supplied by branches of the facial nerve (VII). The buccal branches of the facial nerve over the cheek ramify to such a great extent that any motor loss after reconstruction is usually temporary. The sensory supply to the cheek is mostly from the trigeminal nerve (V). The medial cheek is supplied by the second division (V₂) through the infraorbital nerve. The lateral cheek to the mandible is innervated by third division (V₃) of the trigeminal nerve. A small lower area of the posterior cheek near the lower ear is supplied by the anterior cutaneous nerve of the neck and by the great auricular nerve, which originates from the cervical plexus (C₂, C₃).

The arteries and veins on the cheek generally need not be taken into account to any great extent when performing superficial flaps on the cheek. There is such a good vascular supply on the head and neck that flaps on the cheek flaps are usually randomly placed in relationship to underlying arteries and nerves. The arterial supply to the cheek is from the external carotid artery, which gives rise to the transverse facial artery and the facial artery. Venous drainage is via the anterior facial vein.

There are, however, two motor nerves that are superficial in part of their course on the cheek and that one needs to be wary of. The first is the temporal branch of the facial nerve, which may be superficial as it crosses the zygomatic arch. The second is the marginal mandibular nerve, which crosses over the mandibular artery as it courses along the edge of the mandible.

Special Anatomic Structures

There are two special anatomic structures in the cheek worth noting: the buccal fat pad and the parotid duct. The buccal fat pad is a large well-defined area in the central cheek with a large amount of fat. Its importance is that it is a good landmark for Stenson’s duct, which is the main drainage channel for the parotid gland. The duct courses over the buccal fat pad and descends anterior to it. If Stenson’s duct is transected and a flap repair done over the leaking area, there will be salivary drainage at the flap edge. Sometimes this will be difficult to see and is unavoidable. However, should this drainage occur, it will generally slow down and go away after a few months.⁵ If one sees the salivary leakage, recanalization of the duct may be attempted with a Silastic tube prior to flap repair; however, in the author’s experience this procedure is often unsuccessful.

Which Reconstructive Procedure

Faced with a cheek defect, how does one select the optimal repair? Generally, healing by second intention on most of the cheek will lead to a noticeable scar except in the preauricular area. In this latter area, even very large wounds may be allowed to heal by granulation, often resulting in a healed wound that may be excellent.

As mentioned earlier, skin grafts are generally not used on the cheek. A skin graft matches poorly with the surrounding and contralateral cheek skin in color, texture, type, and degree of hair growth. Furthermore, a skin graft often will not completely fill in a subcutaneous defect and provides less protection to underlying vessels and nerves than a skin flap. There are, however, two exceptions as to when a skin graft may be useful. First, to repair a defect that resulted from an excision of an aggressive tumor, e.g., angiosarcoma or sebaceous gland carcinoma. In this case, a split-thickness graft could be used to immediately repair the defect and to provide a window through which a tumor recurrence could be seen (see Figure 13.1). The second circumstance for doing a split-thickness graft would be to repair a very large defect, which could not be repaired in any other way. Prior to the development of large cheek flaps and cheek–neck rotation flaps, multistaged cheek rotation flaps⁶ or large skin grafts were commonly used to repair cheek defects.⁷

Figure 13.1 (a) Large wound on right cheek after excision of multiple recurrent level II lentigo maligna. (b) Medium-thickness, split-thickness skin graft sutured into wound. Note bolster sutures to tack graft onto recipient wound so as to keep graft from slipping during healing. (c) Healed result 6 months postoperatively.

The single largest decision when contemplating a cheek reconstruction is whether to repair a wound with a side-to-side linear closure (complex repair) or a skin flap. The same defect that may be repaired side-to-side in an elderly person with excess skin and wrinkles may require a skin flap for closure in a younger person to avoid scar spreading from excess tension.

This author has found empirically that the best way to determine whether a complex repair or a skin flap should be done is to lift the ends of the wound up along the relaxed skin tension lines. If the wound edges close easily across the wound with the skin hooks tenting up the wound at the superior and inferior ends, then a side-to-side linear repair may be done. Sometimes, however, a side-to-side repair may be done but distortion of the melolabial fold may occur. In this instance, a flap may be preferable. When possible, however, one should close a wound with a side-to-side linear repair since it will result in fewer incision lines than those from a skin flap.

Reconstruction Philosophy

In reviewing the literature on cheek reconstruction, this author was struck by two trends. The first is that surgeons like to do one specific flap type for one specific defect at one time. This issue has been raised by other authors.^1,8 Part of the reason for this approach has been that surgical training programs emphasize repairing the whole wound at one time; leaving part of the wound open is heresy. The second trend is that even medium-sized wounds on the cheek are repaired by rather large flaps extending into the neck and shoulder when these same wounds could have been closed with an equally good or better result by smaller, less complicated local flaps. The latter trend to do cervical neck or cervical pectoral flaps results in excessive surgery. This is not to say there is not a time and place for such flaps, but many of the case examples presented in the literature show medium-size wounds that could be repaired in other ways.⁹

Flaps to Avoid

On the cheek, two flaps that this author avoids are the subcutaneous island pedicle flap and the bilateral advancement flap. The former usually is very puffy and does not lie flat;¹⁰ the latter produces too many straight lines that are easily seen.

Medial Cheek

The medial cheek usually has significant skin laxity. If the wound is small to medium in size and its long axis is oriented vertically, a side-to-side repair may easily be done (Figure 13.2). If possible, repairs in this area are closed along the nasofacial angle or melolabial fold. Although some authors⁹ advise deep “periosteal” tacking sutures for side-to-side linear closures in the nasofacial angle, this author does not do this and feels it is usually unnecessary. For vertically oriented wounds on the medial cheek that cannot be closed without excessive tension on the wound edges, the rhombic transposition flap with a double Z-plasty is useful (Figure 13.3). This flap takes advantage of the inferior loose tissue available on the cheek. The double Z-plasty helps to increase the extension of the rhombic flap.¹¹ The angulated incisions of the rhombic flap and Z-plasties generally blend in very well over time.

Figure 13.2 (a) Elliptical wound with long axis oriented vertically on medial cheek. (b) Side-to-side repair. Note running over-and-over sutures. (c) Healed result 1 year postoperatively.

Figure 13.3 (a) Large elliptical wound on medial cheek with long axis oriented vertically. (b) Rhombic flap with double Z-plasty cut and undermined. (c) Flap transposed into wound. (d) Flap sutured into defect. (e, f) Healed result 6 months postoperatively.

For a medial cheek wound with its long axis oriented horizontally, a side-to-side linear closure vertically oriented along the maximum skin tension lines would lengthen the suture line considerably. Therefore it might be best to consider a flap closure. There are three main flap choices for such a wound in this area: the subcutaneous island pedicle flap, the rhombic transposition flap (Figure 13.4), and the advancement flap with a back-cut (Figure 13.5