Undercutting and lifting the skin

The extent of the undercut depends on the amount of excess skin on the neck and, to some extent, on the face. With the SMAS lift, the extent of the undercut is much less than with the older, classic rhytidectomy techniques. A larger undercut increases the risk of disrupting the blood supply and developing small seromas, hematomas, and irregularities. However, when there is a large excess of skin and subcutaneous muscle on the neck, it is often necessary to separate the skin from the underlying muscle and then suture them sequentially, thereby achieving maximum improvement. In general, the SMAS and deep facial tissue lift is effective and much safer than separating the skin all the way to the buccal-labial fold. Although some surgeons still prefer this older technique, today it has been shown that such a large amount of skin separation is no more effective than SMAS transfer techniques in correcting the cheeks and deep buccal-labial folds.

The skin undercut is started in the retroauricular area and can be done with special beveled scissors by advancing and spreading the jaws. An alternative is direct dissection with a scalpel. It is important to start the undercut in this area below the level of the hair follicles to avoid damaging them and creating permanent alopecia. However, when the dissection is advanced forward from the hairline behind the ear, it should be fairly superficial, just beneath the skin. This subcutaneous layer is minimal in the retroauricular area and the skin is in very close contact with the fascia of the sternocleidomastoid muscle. Here the skin must be carefully separated until the dissection passes anterior to this muscle. As mentioned above, injury to the greater auricular nerve may occur here because of the thinning of the subcutaneous layer and the close adherence of the dermis to the fascia. Dissection is then continued in the subcutaneous plane, superficial to the platysma muscle and as far anteriorly as is required for the neck procedure. Often the skin undercut is complete and merges with the cavity previously created in the submental area. Although the skin can be isolated slightly above the edge of the mandible, this process is usually limited to the neck area.

After the neck is dissected, the skin is undercut in the temporal region. The temporal lift is required to smooth the skin of the lateral brow and from the outer corner of the eye to the temple. Incisions are made downwards through the scalp tissue, the superficial layer of the tendon helmet, and the superficial layer of the temporal fascia. In this layer, dissection can be performed all the way to the lateral brow and the upper border of the zygomatic arch. Elevation of the temporal block is not required in all types of facelift, in particular, it is usually not required in type I. It is usually done when there is tissue weakness in the lateral orbit and brow that must be repositioned to avoid wrinkling when the cheek tissue is lifted upward. The temporal lift can be combined with other methods of lifting the frontobrow complex, or it can be done alone. The tissue dissection then begins in front of the ear, at the level of the temporal hair bundle, directly in the subcutaneous layer. This layer is markedly different from that in the temporal dissection. Here, the SMAS bridge and the vascular-nerve bundles running upwards in the direction of the frontalis muscle must be left intact. By preserving this "suspension bridge" of tissue, the surgeon will not damage the frontal branch of the facial nerve. The undercut can be continued into the malar region, extending from the ear forward by 4-6 cm, depending on the elasticity of the skin. This process progresses in the intrafatty layer, easily separating the superficial part of the subcutaneous fat left on the skin flap from its deep part covering the SMAS. This anterior-auricular space is connected to the same level of dissection on the platysma muscle. Careful hemostasis is mandatory.

Depending on the type of facelift, the extent of intervention and manipulation of the SMAS layer must be determined. Even a type I facelift may require overlapping suturing or manipulation in the deep layers, depending on the need to lift the midface tissues. If only a small amount of tissue from the mandible and cheeks is to be moved and a posterior displacement of the platysma is required, the only intervention may be the creation of a SMAS fold. However, it is necessary to remove the crescent-shaped fat tissue that still remains on top of the SMAS, in front of the ear, so that the SMAS can be superimposed on itself when suturing. Otherwise, fibrous adhesions of the SMAS will not develop and the effect of the lift may be destroyed after the sutures dissolve. Some surgeons prefer to create this duplication with non-absorbable sutures because of the need to maintain it in position for a long time.

In general, facelifts require some undercutting of the SMAS layer and platysma so that they can be moved back and up. The degree of this undercutting will be dictated by the need to lift the cheek, platysma, and midface tissues. This is determined by the degree of SMAS overlap as the SMAS is lifted, repositioned, trimmed, and sutured end to end. This can be done with permanently absorbable sutures, but not permanent ones.

In patients requiring a midface lift, at a minimum, a deep plane lift modification is performed. This requires lifting the SMAS layer to the level of the zygomatic arch, above the zygomatic eminence and superficial to the zygomatic muscle. Full deep plane lift techniques involve undercutting the SMAS layer anteriorly to the anterior margin of the masseter muscle and connecting it to the elevated neck tissue superficial to the platysma muscle. However, in the midcheek, it is necessary to go into the superficial layer covering the zygomatic muscle, otherwise damage to the nerve branch innervating this muscle or the buccinator muscle may occur.

After appropriate detachment of the midface tissues with their respective sections of the SMAS and platysma, this layer is repositioned in the desired posterosuperior direction. Direct vision allows the buccal-labial tissues and the lower cheek to be seen moving posteriorly and superiorly into a position consistent with a more youthful appearance. Frequently, the SMAS fascial band is fixed to the strong tissues anterior to the ear. That is, the SMAS is transected at the level of the auricle and the inferior SMAS and platysma band is sutured with 0 Vicryl suture as a suspender strap to the mastoid fascia and periosteum. This ensures a firm, well-defined contour of the cervicomental angle. The excess platysma and SMAS are trimmed and a few sutures are placed in the posterior postauricular fascial tissues. Anteriorly, the SMAS is transected and the excess is removed; The SMAS is sutured end-to-end with long-lasting absorbable monofilament sutures such as 3/0 PDS.

[ 1 ]