The sub-SMAS (deep-plane) facelift is based on sound surgical principles of tissue mobilization, advancement, and repair. It is important to remember, when repositioning tissue, that the structures influenced by undermining are usually from the point ofincision to the most distal point ofdissection, but not beyond. The surgical incisions for the two operations are identical.

Platysmal plication is performed when there is notable laxity to the anterior platysmal fibers. The technique for this portion of the operation is also identical for both the SMAS and deep-plane operations.

A subcutaneous dissection is begun in the pretragal area and is extended approximately 3 to 4 cm toward the cheek. It continues inferiorly into the neck, below the body of the mandible. This preplatysmal plane is widely undermined toward the midline, joining the subcutaneous submental dissection overlying the previously plicated anterior platysmal bands.

In the scalp, the temporoparietal fascia and galea are separated from the deep temporal fascia in an areolar plane, with care taken to avoid injury to the temporal branch of the facial nerve as the dissection proceeds anteriorly toward the lateral brow.

Entrance to the sub-SMAS deep plane in the face is facilitated by retracting the skin and subcutaneous tissues, tenting up the SMAS and the platysma. An incision is outlined (leaving approximately a 1-cm "tongue" of SMAS attached to the skin) from the malar region, extending inferiorly toward the posterior border of the platysma, just beneath the angle of the mandible. Traction is maintained as the SMAS is dissected from the deeper parotidomasseteric fascia. Dense fibrous attachments between the superficial and deep fascias exist along the zygomatic arch, overlying the parotid gland, and along the anterior border of the masseter muscle. A less adherent areolar plane exists between the superficial and deep fascias in the cheek, directly overlying the masseter muscle, and beneath the platysma. Dissection is facilitated by vertically spreading the scissors directly along the underside of the platysma, peeling the fat and loose areolar tissue off this structure. Sharp dissection is required to transect the parotidocu-taneous, masseteric cutaneous, and zygomatic osteocutaneous ligaments. The sub-SMAS plane is suprisingly avascular, but for a perforating branch of the transverse facial artery, which is relatively constant in the cheek.

The extent of anterior dissection is dependent on the amount of mobilization necessary to attain the required aesthetic result. To influence the malar bags, dissection must proceed beneath the inferior border of the orbicularis, transecting the thick osteocutaneous ligaments of the malar pad (MacGregor's patch). The nasolabial fold is approached by undermining the fascial-fatty layer of the cheek overlying the major and minor zygomatic muscles. Blunt finger dissection easily separates this plane overlying the mimetic muscles and continues anteriorly toward the nose and upper lip. As the facial nerve innervates these muscles from their deep surfaces, it is important for the surgeon to remain in a plane superficial to the zygomatic muscles. If this area is approached from the inferior subplatysmal dissection, the nerve can become subject to injury, as the SMAS envelops these muscles, and there is danger of dissecting beneath them into this deeper plane. The dissection of the prezygomatic area can be connected with the subplatysmal undermining as the dissection proceeds inferiorly. Fibrous attachments between the two planes are severed, but the confluence of mimetic muscles at the corner of the mouth (modi-olus) is not disturbed.

The jowl area is undermined. An areolar plane exists overlying the masseter muscle, allowing the SMAS to be rapidly elevated by means of a blunt technique from the anterior border of the parotid gland as far forward as the anterior border of the masseter, where the fibrous septae of the masseteric-cutaneous ligaments are encountered. These are severed, and the dissection in the subplatysmal plane is continued anteriorly over the masseter muscle border and inferiorly to the border of the mandible, extending anteriorly to where the facial artery crosses. As long as the underlying parotidomasseteric fascia is not violated during this dissection, injury to the marginal mandibular nerve and vessels is highly unlikely. Further subplatysmal dissection inferior to the mandible is unnecessary. A subcutaneous plane in the neck has already been created.

Once the flap is adequately mobilized, hemostasis is ensured and the resultant widely undermined multiplane, musculocutaneous flap can be advanced to attain the desired aesthetic effect. The temporal brow area is elevated by superior advancement of this flap. Excess tissue is excised beginning at the most anterior extent of the wound. Inappropriate tension to elevate the eyebrow should be avoided. As closure proceeds inferiorly in the area of the superior pinna, the side-burn is brought more posterior rather than elevated, to prevent the temporal tuft from being overlifted. Before closure of the cheek flap, redundant preauricular subcutaneous tissue is excised to better define the tragus from the preauricular area. To facilitate advancement, the SMAS and the platysma are freed from the overlying skin for about 1 to 2 cm, creating a small strip of SMAS that can be used for suturing. The cheek flap is closed by suturing this SMAS tongue to the firm preauricular tissues with 4-0 polyglycolic acid sutures. These sutures, tied under some tension, determine the direction of the vector forces on the mobilized flaps and take tension off of the skin before closure. The superior suture advances the cheek in a posterosuperior direction. Three intermediate sutures anchor the flap posteriorly just anterior to the tragus, softening the melolabial fold and jowl while substantially obliterating the subcutaneous preauricular dead space. The inferior suture's vector is almost directly posterior, anchoring the platysmal flap to the dense fascia of the retrolobular area. This helps to restore the lower jowl and to delineate the jaw-line and the upper part of the neck. The excess SMAS flap and any irregular fascial-fatty tissues are trimmed and smoothed with scissors. Any areas of dog-ears or puckering can be dealt with by judicious subcutaneous undermining; however, to retain the compound flap, more extensive undermining between skin and SMAS should be avoided.

After the flaps have been adequately mobilized and advanced, the skin is trimmed and sutured. Excision proceeds in a sequential fashion. To better delineate the tragus, the small flap of skin advanced over it is judiciously defatted and closed without tension with interrupted fine nylon sutures. Cervical skin is likewise excised and sutured without tension, making sure that hairline disruptions or step deformities do not interrupt the normal individual anatomical configuration of the postauricular and occipital area. Subcuticular 5-0 plain catgut is used to close the postauricular wound, and stainless steel staples are used for the hair-bearing incisions.

Drains are used routinely. They emerge from a separate occipital stab incision and are connected to a negative-pressure reservoir. The drain and dressings are removed the day after surgery, and the incisions are examined. A looser protective dressing is applied for another 2 days, after which the patient can shower and wash his or her hair daily. The sutures and staples are removed after 1 week.

The traditional SMAS technique differs from the above deep-plane technique primarily in that the skin is undermined widely and it is separated completely from the underlying SMAS layer. This requires that a long skin flap be created which is at some risk of ischemia at the edges. In the SMAS technique the SMAS is incised parallel and 1 cm below the zygomatic arch from the pretragal area anteriorly for approximately 4 to 5 cm and undermined and raised in continuity with the posterior border of the platysma. The platysmal flap is begun by continuing the incision of the SMAS flap downward along the midportion of the sternocleidomastoid muscle. At the posterior border of the platysma muscle the flap is elevated anteriorly approximately 7 cm or as far as the anterior platysmal border if necessary. The superior limit of this undermining is a line running 2 cm below the border of the mandible in order to prevent injury to the marginal mandibular nerve. Next the flaps are separately positioned with the SMAS advanced posterosuperiorly, the platysma posteriorly, and the skin usually in a slightly different vector than that of the SMAS flap, to prevent a "pulled look."

The operating time should be similar for the two procedures if not less for the deep-plane technique because it requires that only one flap be elevated, rather than two, and there is usually less bleeding in the sub-SMAS dissection plane than in the subdermal dissection plane.

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