Chapter-44-Lamellar High SMAS Face-Lift

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Chapter 44 Lamellar High SMAS Face-Lift

T E C H N I Q U E S

■■ SMAS Dissection

parotid fascia and SMAS is often indistinct. If a portion of the parotid fascia is incidentally raised with the SMAS flap in exposing the lobular surface of the gland, this is of no clinical significance and should be used by the sur- geon as an aid in identifying the proper plane slightly more superficial. ■■ A distinct plane does exist, however, medial to the parotid between the SMAS-platysma and the paroti- domasseteric fascia. This plane is most easily identified in the lower cheek where it can be entered by gentle blunt dissection. The parotidomasseteric fascia will be seen as a thin, shiny transparent layer covering the mas- seter, buccal fat, and facial nerve branches. Blunt dis- section on top of this layer is safe; however, care must be taken to not violate this layer as it can result in a facial nerve injury. Sub-SMAS dissection must be car- ried over the anterior border of the parotid in the lower cheek to ensure the parotidomasseteric ligaments are released; otherwise, an optimal SMAS effect will not be obtained. ■■ As SMAS flap dissection is made medially in the upper cheek over the superior portion of the parotid and its accessory lobe, the SMAS will be seen to thin and invest the lip elevators. At this point, the dissection must be taken superficial to the superior portion of the zygo- maticus major muscle. Just at the malar origin of this muscle, the zygomatic ligaments will be found. These fibrous connections between periosteum and skin must be divided, and when completely released, a dramatic liberation of the flap will be obtained.

■■ To begin, markings are made for the SMAS flap. A line is marked “high” over the midportion of the zygomatic arch from the infraorbital rim to a point 1 centime- ter anterior to the superior portion of the tragus. The marking is then turned inferiorly and carried over the preauricular portion of the parotid 1 to 2 cm anterior to the ear and continued inferiorly and posteriorly to the anterior border of the sternocleidomastoid ( TECH FIG 3A ). ■■ Flap elevation is begun by incising the SMAS over the zygomatic arch. This is done by grasping the preauricu- lar tissue overlying the lateral arch with an Allis clamp on each side of the marked line. Metzenbaum scissors are then used to incise along the marking medially for a few centimeters. Allis clamps are then released and reapplied incrementally as the incision proceeds medially along the marked line. A considerable amount of tissue lies over the arch, and the frontal branch will be safely beneath half a centimeter or more of fibrous fat. ■■ The preauricular limb of the SMAS incision is then made using the same technique, and these two incisions define the “high” SMAS flap to be elevated. ■■ Next, the corner of the flap is grasped with Allis clamps, and elevation is begun with scissors. Undermining should be limited in the preparotid cheek, more extensive over the zygoma and upper midface ( TECH FIG 3B ). ■■ Sharp scissors dissection of the flap is usually required posteriorly over the parotid where the plane between

B

TECH FIG 3  • Plan for “high SMAS” flap. A. The superior margin of flap is planned over the zygomatic arch and not below it. The frontal branch of the facial nerve ( dashed line ) lies safely posterior and deep to the majority of the dissection. B. Approximate extent of SMAS undermining. Complete release of the SMAS flap will require that both the parotidomasseteric ligaments ( squares ) and the zygomatic ligaments ( circles ) be released. C. Completed SMAS flap elevation. Inferior to the origin of the zygomaticus major muscle ( large arrow ), and superomedial to the acces- sory lobe of the parotid, lies the zone of transition between the zygomatic ( blue dots ) and masseteric-cutaneous ligaments ( black dots ) and the most potentially dangerous part of the SMAS dissection. Proper liberation and release of the SMAS flap usually require at least partial division of restraining attachments in this area but move the dissection into very close proximity to the zygomatic branch of the facial nerve ( small arrow ).