Techniques for SMAS Utilization

Experience has confirmed the utility of the SMAS in rejuvenating the face and it has come to be an integral part of many techniques. How the SMAS is used, however, determines its overall effectiveness, and not all procedures can be expected to produce equivalent results.

Many techniques have evolved for utilization of the SMAS. These include Skoog or composite dissections in which the SMAS and skin are elevated as a single unit and advanced along the same vector, "bidirectional" dissections in which skin and SMAS layers are elevated independently and advanced along different vectors, plication techniques in which the SMAS is not elevated but is invaginated with sutures, and SMASectomy procedures in which the SMAS is partially resected and then repaired. High SMAS dissections in which the SMAS flap overlaps the zygomatic arch provide an effect on the midface and recruit and redistribute tissue over the upper malar region.

Composite and Skoog-type dissections are quick to perform and result in a thick, durable flap of both skin and the SMAS. The flap raised in these procedures has good blood supply. Consequently these techniques might be safer in smokers or when skin resurfacing is performed at the same time. They have the disadvantage, however, that skin and the SMAS must be advanced along the same vector and suspended under more or less the same amount of tension. Skin and the SMAS age at different rates and descend along different vectors. Therefore, optimal treatment of each layer is not possible. Skin overtightening, hairline displacement, "wrinkle shift" from the neck to the cheek and other unnatural appearances can result. In addition, if the orbicularis oculi is included in a "composite" flap, its motor nerve supply is often divided and lid dysfunction can result.

Separation of the skin from the SMAS has the advantage that skin and the SMAS can be moved along separate vectors and suspended under different tensions. This produces a better rejuvenation, a natural appearance and fewer secondary deformities. These two directional techniques require a high degree of surgicial skill to elevate the skin flaps without thinning the SMAS flap and are time-consuming (Table 38.1).

Plication techniques are quick to perform and do not require the level of technical skill necessary for a more tedious and potentially more hazardous SMAS elevation. Properly performed plication at multiple

Table 38.1. Superficial musculoaponeurotic system (SMAS) suppor

SMAS support goal

SMAS support produced by:

1. Submental area

1. SMAS separated from parotid and masseter muscle

2. Tissues at the hyoid.

2. Preauricular SMAS flap to mastoid fascia

3. Anterior cheek

3. Support anterior cheek tissues

a) Large SMAS flap posterior-superior shift

b) Sometimes sutures to the malar bone periosteum

c) Separate superior transposition flap

with vector directed toward angle of mouth

d) Release of malar retaining ligament adjacent

to zygomaticus major muscle

4. Angle of the mouth elevation

4. Same as point 3

5. Lower nasolabial fold

5. Posterior-superior SMAS shifting perpendicular

to the fold

6. Upper nasolabial fold

6. a) Major flap incised above zygomatic arch for support

of upper nasolabial fold

b) Separate transposed flap of the superior portion

of the SMAS

c) Suture to the malar bone with support directed toward

the upper fourth of the nasolabial fold

d) Combination approach

7. Nasojugal groove change from aged oblique direction

7. High location of SMAS transection at or above the upper

to youthful, horizontal direction

border of the zygomatic arch or third flap for upper vec-

tor directed toward lower eyelid and upper nasolabial fold

8. Decrease lower-eyelid excessive skin and support

8. Release of all of the attachments of the orbicularis oculi

by facelift skin shift

muscles to the skin (smile crease)

9. Support to the periorbital fat of the lower lid

9. Extension of SMAS flap and transection into the lateral

portion of the orbicularis oculi muscle and shifting

upward in a lateral direction with a high SMAS

transection or a third flap component

Vector Zygomatic Arch
Fig. 38.6. Incision on the upper part of the zygomatic arch can often be made high enough so that a third flap is not necessary to achieve the desired vectors for the cephalad support of the cheek, jowl, midface, submental area, periorbital region, lid-cheek junction and angle of the mouth

Fig. 38.7. High SMAS flap transection is safe with a detailed knowledge of the anatomy of the frontal and zygomatic branches of the facial nerve. The elevation with Allis clamps gives a clearance over the motor nerves of more than 1 cm sites and along multiple vectors can produce long-lasting improvement in patients with moderate deformities. It has the disadvantage, however, that cheek skin must be widely undermined, and plicated tissue may result in visible contour irregularities. Plication techniques often only result in elevation of perioral tissues and the jowl, and provide limited improvement in the midface, cheek, and infraorbital and submental region. Usually plication techniques do not distribute tissue over the upper malar region where it is often needed most.

SMAS excision (SMASectomy) techniques are similar to SMAS plication, except that tissue is excised rather than invaginated. SMASectomy procedures are, however, often limited to tightening of the deep tissues along one vector only. SMASectomy and plication procedures may result in similar changes in the topography of the face. Plication at multiple sites and in multiple directions may produce better results than SMASectomy alone.

The technique we use most often liberates the SMAS from its attachments to the parotid gland, mas-seter muscle, zygoma and mandibular ligament and offers the advantage that the full potential of the SMAS can be realized and maximum repositioning of ptotic tissue to its youthful position can be obtained. If the SMAS is not fully released and mobile, its effectiveness will be compromised. More extended dissections with a high SMAS incision (Figs. 38.3, 38.638.8) have the disadvantage that it is time-consuming, technically demanding and, theoretically at least, the facial nerve branches are placed at a potentially greater risk.

Smas Jowls
Fig. 38.8. Sharp scissor dissection is used to separate the SMAS from the parotid gland and masseter muscle and the SMAS malar connection. The SMAS flap is always adequate for support of the face unless damaged by the surgical technique of elevation of the skin overlying the SMAS

SMAS flaps are planned with a transverse incision over the upper part of the zygomatic arch, as opposed to too low, which loses 75% of the SMAS support potential. This has the distinct advantage that a more cephalad effect can be obtained on the cheek, jowl, midface, periorbital region and lid-cheek junction, and tissue can be redistributed over the upper malar region (Figs. 38.1, 38.55). The high flaps require detailed knowledge of the anatomy of the frontal and zygomatic branches of the facial nerve (Figs. 38.7, 38.8).

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