Tucson, Ariz. -- A deep, elongated superficial muscular aponeurotic system (SMAS) flap with a novel inverted L-shape design produces significant cheek elevation besides reducing sagging in the lower face and neck, according to Robert M. Dryden, M.D., F.A.C.S. and Craig Davis, D.D.S., M.D.
Instead of initiating the apex of the SMAS flap at the traditional point 1 cm below the zygomatic arch, or cheekbone, Drs. Dryden and Davis start the apex 1 cm superior to the zygomatic arch.
A solid understanding of SMAS anatomy underlies the new approach, designed by Dr. Dryden. As a layer of fibrous and muscle tissue located deep to the skin, the SMAS, which is used like a handle to move the fatty tissue of the face, is more substantial above the zygomatic arch than in the midface, says Dr. Davis, a cosmetic surgery fellow of Dr. Dryden's at Arizona Centre Plastic Surgery, Tucson, Ariz.
The connective tissues of the SMAS in the temple area fuse before reaching and entering the zygomatic arch. In the midface however, the SMAS is thinner, composed of wisps of connective tissue. Lengthening the SMAS flap by initiating it in a higher position incorporates the weaker midfacial SMAS into the body of the flap, which the surgeons then suspend over the zygoma. Attaching the suspension and fixation sutures here lodges them in one of the sturdiest areas of the SMAS.
Placing the apex of the SMAS flap above the zygoma instead of below it takes advantage of these anatomic features. The higher flap attachment produces the marked cheek elevation that characterizes this technique.
The SMAS can be brought forward and attached by either plication or imbrication. Plication involves folding the overlapping portion of the SMAS in on itself and fixing it with buried suspension sutures. The imbrication technique removes the SMAS overlap and uses buried suspension sutures to fix the remaining edges. Plication is thought to offer less chance of facial nerve branch injury, but according to Dr. Dryden, "imbrication results in cleaner contours and a more natural appearance, since there's no underlying excess tissue left to bunch up under the skin."
The risk of facial nerve damage increases with imbrication and the dissection of tissues in a deeper plane, but Drs. Davis and Dryden reduce the risk by dissecting the SMAS flap with a monopolar cutting current that passes through a Colorado needle.
"As the dissection plane nears these fibers, an electric current stimulates twitching of nearby innervated muscles. By carefully observing the operative field and juxtaposed tissues, we're warned of impending danger to vital structures," Dr. Dryden says.
The sharp tungsten tip of the needle allows the surgeons to use very low wattages, substantially reducing bleeding and minimizing tissue damage. They can then extend the SMAS flap over the zygomatic arch and into the temporal area despite the density of facial nerve fibers there.
Patients receive sedation or general anesthesia. The surgeons make standard rhytidectomy skin incisions around the ear after injecting local anesthesia and infusing tumescent solution. After initiating the skin flap 1 cm above the zygomatic arch, they elevate it, extending it anteriorly for 2 to 3 cm and inferiorly 2 to 3 cm beneath the mandible-- making it 1 to 2 mm thick.
"The flap should be as thin as possible, staying superficial to the seventh nerve fibers," Dr. Dryden says.
After lifting the flap up and back, about 1 cm of SMAS can usually be overlapped and removed superiorly at the posterior base. Closing sutures are directed up and back to enhance cheek lift.
The technique has been used on approximately 100 patients treated from 2002 through the present, and frequently combined with brow elevation, blepharoplasty, chin augmentation or laser resurfacing. Patient ages ranged from 26 to 85.
The cheek elevation, positioned higher than in traditional facelifts or mini-facelifts, decreases the nasolabial fold and its underlying crease. These results have been variable but present in all patients, Dr. Dryden says.
Complications were minimal, with no incidences of hematoma, motor nerve palsy, skin flap necrosis, infection, or SMAS flap fatigue. Two or three patients had transient seventh nerve palsies that resolved postoperatively.
"The inventive design of this SMAS flap produces superior cheek elevation, and it's a safe and effective way to rejuvenate the lower two thirds of the face" Dr. Dryden says. CST
For more information: Campiglio, GL, Candiani P. Anatomical study on the temporal fascial layers and their relationship with the facial nerve. Aesth Plast Surg. 1997:21;69-74
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