Is There A Best Time To Have A Facelift

Bryan C. Mendelson, F.R.C.S.E., F.R.A.C.S., F.A.C.S.

Melbourne, Australia

The SMAS was described more than 25 years ago, yet its full potential in face-lift surgery has become appreci- ated only more recently. A reappraisal of the various as- pects of SMAS surgery is now appropriate. These include aspects of its release from the deep fascia, the several considerations underlying the vectors of flap redistribu- tion, and the rationale underlying the methods of flap fixation. These are unique, compared with the traditional considerations in subcutaneous face lifts and en bloc sub- periosteal lifts. (Plast. Reconstr. Surg. 107: 1545, 2001.)

ªIf you understand something in only one way, then you do not really understand it at all.º

ÐMarvin Minsky, Society of the Mind, 1987

The essence of most rejuvenation surgery of the face and brow is to mobilize the lax and ptotic tissue (skin based flap with a varying depth of the underlying tissue) and then ad- vance that flap to a somewhat higher position relative to the facial skeleton. The question of ªpreferred direction of liftº is still discussed, although current teaching favors a strong ver- tical lift for best correction. Of necessity, with limited access surgery, vertical traction is all that is possible.

The inclusion of the superficial musculoapo- neurotic system (SMAS) has been the most fundamental change in technique since the beginning of face-lift surgery.1,2 Face-lift sur- gery performed using the traditional subcuta- neous technique has been based on well- established routines. When the SMAS became incorporated in the technique, although it pro- vided a range of enhanced possibilities, it has been associated with some limitations and

problems that have only gradually become understood.

Chief among these was that, although the basic anatomy of the SMAS (the deeper layer of the superficial fascia of the face) was well described at the outset, other most relevant anatomy was not. Particularly significant is the anatomy of the ligamentous attachments be- tween the SMAS and the facial skeleton.3±5 The sub-SMAS region of the medial cheek was con- sidered to be a nearly impenetrable jungle. At that time, is was considered unsafe to dissect beneath the superficial fascia of the cheek, other than over the buccal space where dissec- tion is less difficult.1 Complicating matters is that the SMAS incorporates the muscles of fa- cial expression. Normal function of these mus- cles can be disturbed by SMAS surgery. This complication may arise from nerve damage oc- curring during the dissection or from abnor- mal pulling or distorted movements as a result of incomplete dissection or incorrect fixation.

In the 25 years since the introduction of the superficial fascia into face-lift surgery, there has accumulated a sufficient body of experi- ence and of detailed anatomic knowledge to reflect on the basic principles of SMAS surgery. These explain some of the difficulties that have been associated with the procedure in the past. It becomes apparent that the principles that were so well established for traditional face-lift surgery were not necessarily sufficient for the different requirements with surgery of the SMAS.

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The discussion that follows is a synthesis of empiric observation and established fact. It covers the related topics of extent of release required, vectors of lift, and principles of fixation.

RELEASE

The matter of ªthe extent of surgical release requiredº continues to engage the mind of aesthetic plastic surgeons. When face lifts are performed at the subcutaneous and subperios- teal levels, this is a relatively simple matter, as these face-lift flaps have a relatively uniform attachment to the deeper layer. Considerations of surgical release are more complex in SMAS flap surgery due to the nature of the attach- ment of the SMAS to the underlying perios- teum and deep fascia. There are specific areas of strong ligamentous fixation that require de- finitive surgical release and that contrast with intervening areas of loose adherence, which separate readily, such as the buccal and prezy- gomatic spaces. Those techniques of SMAS sur- gery that involve plication or imbrication of the exposed surface of the SMAS6 ± 8 are fundamen- tally different from SMAS flap surgery, as they do not involve mobilization of a SMAS flap with the attendant surgical release of the areas of ligamentous fixation.

The effect of complete surgical release of the deep ligamentous fixation of the SMAS in the vicinity of the area requiring correction is to

PLASTIC AND RECONSTRUCTIVE SURGERY, May 2001

reduce the resistance of the tissues so that when traction is applied to this area the flap readily moves. Movement ceases when a new equilibrium is reached, i.e., when the laxity has been taken up and the resistance of the tissues again increases to equal the tension force ap- plied (Fig. 1, left and second from left).

Accordingly, the extent of undermining re- quired in SMAS flap surgery is the minimal amount necessary to enable a tension-free re- positioning sufficient to fully correct the area of redundancy. If the SMAS flap is not com- pletely released, the resistance of the tissues to the traction force applied requires the applica- tion of a greater force. This increased force, although not sufficient to overcome the liga- mentous resistance, may result in a stretching of those tissues of the flap between the force point (at which the force is applied) and the point of ligamentous resistance (Fig. 1, second from right). At best, stretching may achieve a temporary correction of laxity, but only while the tension force persists. Although it is possi- ble to suture the SMAS under tension, the tension is not maintained because the SMAS elongates as it undergoes the biomechanical process of stress relaxation.9

In some situations, the application of a trac- tion force to an incompletely released SMAS flap may cause a distortion. If there is a resis- tance to movement that is greater in one direc- tion than another, the magnitude of displace-

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ment no longer relates just to the applied force and the angle of traction as an additional fac- tor comes into play, i.e., rotation of the flap around the point of remaining fixation. The flap does not advance in the direction of the applied force and to the extent expected. Rather, there is an angular displacement such that there may be excessive movement of the flap in the ªwrongº direction relative to the limited movement in the intended direction (Fig. 1, right). A classic example of this distor- tion is the lateral sweep of the cheek.10 This undesirable sequela of face lifts can result from SMAS flap surgery when the anterior masseteric- cutaneous ligaments remain intact and block the intended vertical displacement of the mid- cheek. Instead, the more mobile lower part of the flap along the jaw line rotates around the lowest of these ligaments and is displaced pos- teriorly (Fig. 2).

A similar situation is prone to occur around the lateral canthus when vertical traction is applied to the suborbicularis oculi fascia in this area. If the resistance inferolateral to the force point has been released but the medial restric- tion persists (due to the orbicularis retaining ligament remaining intact), an oblique fold of the flap may result. The outer part of the lower lid remains uncorrected until the restriction to mobility imposed by the resistance of that lig- ament has been released. These examples illus- trate a key principle of SMAS flap surgery that where there is a block between the force point and the area requiring correction, it is not possible for SMAS flap surgery to improve that area.

When SMAS flap surgery was introduced, it was not appreciated that there is a key func- tional differentiation of the cheek into two parts. The outer or lateral cheek (preauricu- lar) is separated from the medial cheek by an internal vertical ligamentous boundary. This boundary is located along the line formed by the angulation of the underlying facial skele- ton at the superior temporal line, the lateral orbital rim, and at the lateral border of the body of the zygoma. The key ligamentous at- tachments of the superficial fascia to the un- derlying skeleton occur along this line. The important muscles of facial expression are lo- cated medial to this line, and it is here where most of the facial aging occurs.5,11,12

As surgery of the SMAS was originally de- scribed, the release was restricted to the outer part of the face. Specifically, it did not release

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FIG. 2. (Above) The lateral sweep deformity of the cheek that can occur in SMAS flap surgery, despite vertical traction. This outcome occurs from the failure to properly release the anterior masseteric-cutaneous ligaments. These ligaments are inherently stronger above, nearer the zygoma, and weaker below. Rotation of the more mobile lower part of the flap results in an excessive posterior displacement, which con- trasts with the insufficient vertical lift. Point X, the pivot point, is the lowest intact ligamentous resistance. (Below) Complete release of the midcheek retaining ligaments allows an even redraping of the superficial fascia of the cheek in the direc- tion of the traction force.

the vertical ligamentous boundary to allow an effect on the medial part of the cheek. The extended SMAS technique, which was a key evolution of SMAS surgery, continues the re- lease beyond this ligamentous line, i.e., it takes

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up the release at the level at which it was dis- continued when performing the traditional SMAS release.13

VECTORS: BASIC PRINCIPLES

According to Oxford, vector is defined as a quantity having direction as well as magnitude, denoted by a line drawn from its original to its final position.

²In the face-lift context, a vector diagram may be used to illustrate the force applied to the flap, or alternatively to illustrate the resultant effect, namely the displacement of the flap.

²When a force is applied in a particular di- rection (e.g., vertical) the result is maximal in that direction, but there is also an effect at an angle to the primary force (Fig. 3, left).

²If the force is applied at an angle to the vertical, the resultant effect has both a ver- tical and horizontal component (Fig. 3). This effect can be demonstrated by use of

PLASTIC AND RECONSTRUCTIVE SURGERY, May 2001

the X-Y coordinates of classic two-dimen- sional geometry. These show how the rela- tive distribution of effect between the verti- cal and horizontal varies according to the angle at which the force is applied. With a 45-degree angle of traction, there is as much vertical lift as posterior displacement (Fig. 3, right). Although vertical lifting is paramount for a successful face lift, it is important to realize that a component of vertical lift also occurs with face-lift flaps, which have other than directly vertical traction. As a corollary, a major vertical lift can be achieved while at the same time providing a significant com- ponent of posterior displacement. When oblique traction is applied to the lateral face (i.e., lateral to the body of the zygoma), this reduces the distortions that are prone to result from a purely vertical lift, such as crowding of the lateral canthus crow's foot, area, and excessive upward displacement of the sideburn.

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FIXATION

The dermis of the face is attached to the facial skeleton by a multilink fibrous support system that comprises the retaining ligaments and the superficial fascia, which includes the SMAS and the retinacula cutis.11 A taut and intact retinacula cutis faithfully transmits the shape and movement of the superficial fascia to the skin. The function of the face imposes unique and conflicting requirements on its su- perficial fascia, namely the need for both fixa- tion and movement. The functions of facial expression demand precisely controlled move- ment such as occurs with lip control in articu- lation. To restrict the amount of movement to the degree intended and to the area of the face intended, stability of the tissues is required, which takes the form of the deeper fixation of the superficial fascia. An example of the local- ization of movement is the prevention of trac- tion on the lower lid when the muscles around the mouth contract. Strong fixation is also re- quired to resist the external forces of gravity and of traction, such as occurs in sleeping with the cheek buried in a pillow.

The anatomic pattern of ligamentous fixa- tion of the superficial fascia to the facial skel- eton defines boundaries that compartmental- ize the face into several regions (Fig. 4). Three of these are component parts of what is exter- nally visualized as the cheek, i.e., the lateral cheek and the prezygomatic and infrazygo- matic parts of the medial cheek, in addition to the other regions, the lower lid, lower temple,

FIG. 4. Regions of the face. Compartmentalization occurs from the pattern of ligamentous fixation of the superficial fascia to the periosteum and deep fascia. The boundary of each region is formed by a ligament.

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upper lid, and forehead. The stabilizing effect that occurs at these ligamentous boundaries quarantines the movement resulting from mus- cle contraction within each region so that, at least in youth, movement does not transmit into the superficial fascia of adjacent areas. The ligamentous fixation has a shock absorber- like effect, which modulates the degree of tis- sue displacement upon muscle contraction.

The laxity that develops in the multilink fi- brous support system of the face is due to a progressive weakening of the supporting con- nective tissue. This presumably arises from the combination of intrinsic, age-related atrophy and degeneration of the connective tissue com- pounded by the ªwear and tearº effect from the repeated displacement of the soft tissues con- sequent on the action of the facial muscles. Once some initial laxity develops, an exponen- tial effect would occur as the laxity places more strain on the remaining and slowly diminishing ligamentous support. Whereas, in youth a bal- ance exists between fixation and movement, the reduction of effective fixation means that the effect of the same muscle contraction tends to produce a greater displacement of the soft tissue with aging. The increased displacement further strains and weakens the ligamentous support.

These events would account for the acceler- ation of the rate of aging changes commonly seen in a woman in about her mid-forties. They also account for the apparent hyperactivity of muscle contraction, e.g., smile lines and gla- bella lines, at an age when muscle mass and strength are, in fact, beginning to weaken. Ob- viously, the influence of gravity is the same in youth as it is in age, but tissue displacement with gravity is limited in youth. Descent of tis- sues from the effect of gravity only occurs when the tissues have become lax. The displacement of the tissues from gravity tends to further weaken the ligamentous support. Although the vertical descent of the face so characteristic of aging14 reflects the obvious effect of gravity, the cause of the underlying laxity reflects the in- creasing mobility of the tissues as a result of the muscular activity rather than the laxity having arisen primarily from the long-standing influ- ence of gravity (Fig. 5). Notwithstanding, that laxity can occur in the absence of muscle activ- ity (and muscle tone) as seen in long-standing facial nerve palsy.

The direction of the weakening and of dis- placement of the connective tissues from repet-

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FIG. 5. The displacement of soft tissue that occurs under the influence of gravity is conditional on laxity being present. The correction of laxity in the vector of displacement (seen here as taking the slack out of the chain) nullifies the apparent effect of gravity.

itive muscle shortening and stretching differs according to the configuration of each muscle (Fig. 6). For linear muscles, e.g., zygomaticus major and corrugator supercilii, the laxity tends to be parallel to the direction of short- ening of the muscle fibers. Whereas, for those muscles in which the fibers follow a curve, e.g., orbicularis oculi pars orbitalis and medial platysma, contraction of the muscle fibers causes a radial, or centripetal displacement force on the supporting connective tissue. Over time, medial platysma contraction even- tually pulls the supporting tissue away from the depth of the neck concavity. It is not the mus- cle contraction that changes over time but the laxity of the fascial support that allows the platysma banding. Similarly, the part of orbic- ularis oculi that courses over the temple even- tually becomes displaced toward the lateral canthus as a result of a weakening of its fibrous support, as does the part of orbicularis oculi that directly overlies the body of the zygoma. The action of orbicularis oris, the most power- ful muscle of facial expression, is the major

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factor contributing to laxity of the medial cheek, which is the most mobile and least sup- ported part of the face. The tissue displace- ment is directed medially, but when laxity de- velops, it is held up at the nasolabial furrow.

There are multiple vectors of displacement in the aging face. This is because each of the muscles of facial expression has its own direc- tion of connective tissue laxity. The correction of each vector of displacement requires its own vector of fixation. Fortunately, use of the SMAS provides increased opportunities for control- ling the directions of lift. This situation is quite different from that in subcutaneous and sub- periosteal flap surgery in which a single, mostly vertical, vector is used. Once the retaining lig- aments have been fully released, several ana- tomic regions have been entered into and have become as one. With the original, limited re- lease SMAS surgery, it was considered to be an advantage to have two vectors; one direction for the SMAS, and a different vector for the skin flap.15 When a properly released SMAS flap is used, multiple vectors are possible.16,17 The use of multiple vectors enables the appro- priate vectors of correction for each region of the face.

If strong, nonabsorbable sutures are used for the surgical fixation, what is effectively being performed is a replication of the original type of ligamentous fixation akin to that in joint surgery.17 These sutures can hold a substantial, ligament-like, strength into the superficial fas- cia if they are placed where the fascia is rein- forced. This reinforced area occurs where the retaining ligaments pass through the SMAS into the retinacula cutis. Rather than suturing the mobilized SMAS to a mobile area, as occurs in suturing to the nonmobilized SMAS, the SMAS flap can be fixed rigidly if it is sutured back to the appropriate part of the underlying periosteum or deep fascia. In restoring the anatomy of ligamentous fixation, the sutures appose the SMAS directly to the periosteum, which is in contradistinction to the use of looped suspension sutures. The closer the force point for application of tension to the fixation point on the skeleton, the less poten- tial for subsequent loss of position as a result of relaxation of the intervening bridge of SMAS. The use of multiple sutures spreads the load and reduces the force per unit area at each fixation point.

The sutures into the SMAS flap need not be restricted to the cut edge of the flap. With the