30 Liposuction and Minimally Invasive Fat Reduction
A thorough understanding of the fat compartments is essential in determining which facial procedure will provide the optimal outcome.
Liposuction of the neck alone in patients with fat deep to the platysma will result in less than optimal outcomes.
Treating the neck in isolation when the lower third has advanced aging will result in suboptimal outcomes.
Conventional liposuction and selective laser lipolysis provide comparable results in the isolated treatment of the preplatysmal fat compartments of the neck.
Laser lipolysis is a powerful tool for sculpting the fat compartments above the jawline and for secondary liposuction of the neck and in the fibrous fat compartments overlying the parotid gland and lateral neck.
The beauty of the face and neck is defined by the contours and balance of adjacent structures. Patients presenting with concerns related to their facial shape are affected by the intrinsic nature of their facial anatomy. As patients age, the intrinsic factors are further influenced by weight gain or loss, loss of the facial bony skeleton, and loss of skin elasticitydue to environmental factors, such as sun and smoking. Aesthetic contouring of the face can be achieved by the addition and subtraction of volume and the rearrangement of displaced volume, as well as by tightening the supporting structures and excision of redundant tissues. Fillers or volumizers can replace and augment areas of deficiency.1–4 Repositioning of displaced volume can be readily achieved with formal surgical lifts.5 The removal of volume as an isolated procedure can improve the contours of the face and neck, particularly in the younger patient and in highly selected older patients. Typically, a combination of procedures is required to restore the aesthetic shape and balance in the aging patient.
This chapter focuses on liposuction and laser-assisted lipolysis to reduce fat and improve the face and neck contour. As emphasized here, appropriate patient selection is the key factor to a successful outcome.
Background: Basic Science of Procedure
Liposuction of the face has historically been confined to the neck and the portion of the jowl that extends below the face–neck interface.6–8 In 1989 McKinney and Cook6 suggested that liposuction of the jowls and nasolabial folds be done concomitantly with facelift procedures, but the suggestion was met with limited acceptance. Traditional liposuction techniques above the jawline can lead to contour irregularity because of cannula size, difficulty in selectively removing fat from individual compartments, and variable overlying skin response. Some surgeons have difficulty achieving predictably smooth contours, even with microsyringe liposuction. In the neck, the fat below the jawline can sometimes consist of a greater amount of fibrous tissue that makes liposuction cannula passage difficult. Over all, though, the authors have found conventional liposuction utilizing cannulas 3 mm and smaller to be equally as effective as laser lipolysis in managing the preplatysmal fat.
Several new laser applications on the market target the fat of the body and the face.9–14 Depending on the laser wavelength, there is variable specificity for fat and water ( Fig. 30.1 ).15 Selective lipolysis of the targeted fat compartment for regional contouring can lead to less risk of nonspecific collateral tissue damage, such as in the overlying skin.
A selective laser expands options for a multimodality and individualized approach to the treatment of the aging face by shaping the jowl and neck fat, tightening the overlying skin, and targeting other areas of fatty irregularities in the perioral area. As our understanding of the aging face is evolving in relation to volume shifts, volume loss, and volume accumulation, one can more specifically target treatment to the variable regional changes within the same face. In other words, the approach to the aging face can include volume removal with direct excision, traditional liposuction, and laser-assisted lipolysis, as well as volume addition with autologous fat, filler, and alloplastic implants, in addition to repositioning facial fat and muscles with various midface and necklift procedures.
Fat Compartments of the Face
The subcutaneous fat of the face has long been considered to be a unified confluent mass. Historically, great attention has been paid to the process of skin aging, laxity, loss of elasticity, and sun damage. Recent studies of the face and its underlying adipose layer reveal a mosaic of subcutaneous fat compartments with distinct boundaries and associated findings relating to the process of aging.16–18 In their landmark study, Rohrich and Pessa16 describe the partitioning of subcutaneous fat of the face in multiple independent anatomical compartments ( Fig. 30.2a,b ). Facial fat is therefore divided into discrete facial subunits corresponding to several fat compartments found in each facial region. Examples of such regions are the forehead, the periorbital area, the cheeks, and the jowls.
The forehead is a collection of three anatomical units, including central, middle, and lateral-temporal cheek fat. Periorbital fat is also divided into three distinct regions: superior, inferior, and lateral. In the cheek, what has been referred to as malar fat is composed of the following three separate compartments: medial, middle, and lateral-temporal cheek fat. The nasolabial fold, nonetheless, is a discrete unit with distinct anatomical boundaries.
Histology of the septal boundaries between the several adjacent fat compartments demonstrates a fibrous condensation of connective tissue that forms diffusion barriers. The septa originate from underlying fascia and insert into the dermis of the skin. These septa form an interconnecting framework that limits shearing forces on the face and provides a retaining system for the face. Perforating vessels arising from the deep arteries of the face travel through these septa to supply the skin and define the overlying vascular territories, or angiosomes, of the face.19
This chapter expounds on the anatomy of the lower face and neck because volume reduction and liposuction of the nasolabial, jowl, and submental fat has demonstrated significant improvement in the contouring of the face.
Nasolabial Fat Compartment
The nasolabial fat lies anterior to medial cheek fat and overlaps the jowl fat. The orbicularis-retaining ligament represents the superior border of this compartment. Nasolabial fat can be noted medial to the deeper fat of the suborbicularis fat compartment. The lower border of the zygomaticus major muscle is adherent to this compartment.16
With aging, the fullness in the nasolabial fold represents a form of pseudoptosis. The volume of the nasolabial fat compartment is preserved while the superficial cheek fat compartment deflates and accentuates the appearance of a prominent fold.19
In the lower face, the jowl fat has been defined as a collection of overlapping subcutaneous fat compartments above and below the mandibular border. Two subcutaneous compartments above the mandibular border make up the substance of the jowl fat, a superior compartment and an inferior compartment.17
The superior jowl compartment clinically appears as the most inferior extension of the nasolabial fold. Anteriorly, it consistently approximates the oral commissure. Posteriorly, it relates to at least two regions: superiorly to the fat overlying the malar hollow and inferiorly to the inferior jowl fat pad. Despite the proximity of buccal fat to the jowl, it represents an anatomically separate compartment deep to the jowl fat. Buccal fat does not contribute to the location or degree of jowling.17
The inferior jowl fat compartment rests inferior and posterior to the superior jowl fat compartment. Superiorly, it abuts the superior jowl fat pad and fat from the malar region. Anteriorly, the superior jowl fat descends to meet it. The posterior border is the fat overlying the parotid-masseteric fascia. Inferiorly, the subcutaneous fat reaches the mandibular border. The inferior jowl fat overlaps the submandibular fat pad caudally.
The mandibular septum is the superior border to the submandibular fat compartment located immediately below the border of the mandible. It borders the inferior jowl fat compartment superiorly. Anteriorly, it relates to fat in the submental area, and posteriorly it relates to fat that descends across the border of the mandible from the parotid-masseteric region. The inferior border of this compartment relates to the fat over the sternocleidomastoid muscle.17
Submental Fat Compartments
Adipose tissue in the anterior neck is located in three different layers. It is described in relation to the superficial cervical fascia that splits and encases the platysma in the submental region. The supraplatysmal fat is found within the subcutaneous tissue and contains greater amount of fat in the submental region as compared with the surrounding fat.19
Between the medial edges of the platysma muscles and inferior to the level of their decussation exists a more fibrous fatty tissue. The consistency of this interplatysmal fat compartment is related to the hyoid ligament and its attachment to the hyoid bone, the perihyoid fascia, and the anterior digastric muscles. Therefore, interplatysmal fat removal is likely to require direct excision, whereas liposuction techniques are usually reserved for the supraplatysmal fat compartment.
Deep to the platysma muscles and extending over to the medial wall of the submandibular gland capsule is a compartment of fat that is superficial to the anterior digastric muscles. This subplatysmal fat can be abundant, in some patients extending down to the suprasternal notch.20
The Facial Nerve
Facial nerve paralysis is a rare but dreaded complication following aesthetic facial procedures. In the lower face and neck, the marginal mandibular nerve and the cervical branch of the facial nerve are both subplatysmal, where injury can be avoided if the plane of dissection remains superficial to the platysma muscles.
Laterally, the marginal mandibular nerve is well protected by the substance of the parotid gland. Anterior to the anterior edge of the parotid, it courses deep to the superficial muscular aponeurotic system (SMAS) layer and, in most patients, below the border of the mandible. Beyond the facial vessels, the marginal mandibular nerve is located above the mandibular margin and can be damaged as the platysma thins anteriorly. Paresis of the mandibular nerve presents as weakness of the lower lip depressors.19
The cervical branch exits the parotid gland at its caudal tip and then splits to superior and inferior branches. Both branches enter the platysma laterally and course within the muscle. Injury to the cervical branch can present as pseudoparalysis of the marginal mandibular nerve, because the platysma cofunctions with the lower lip depressors as a depressor of the corner of the mouth.21
The superficial venous system in the neck is, for the most part, subplatysmal and therefore is rarely a concern during minimally invasive procedures such as suction lipolysis of the subcutaneous tissues. One exception is the path of the external jugular vein along the posterior border of the platysma. In the lateral neck, the external jugular vein is protected only by a thin veil of superficial cervical fascia21 and requires great care not to bluntly injure the vein with a suction cannula.
The anterior jugular vein is found in the subplatysmal layer along the medial aspect of the platysma muscle. It courses within the subplatysmal fat and occasionally connects with the common facial vein with a communicating branch lying along the anterior border of the sternomastoid muscle.20 Due to the anatomical relationship of these venous structures to the deep fat compartments, caution is recommended when one is attempting to remove fat from the subplatysmal layer.
Laser-assisted volumetric contouring is most effective in the lower third of the face and neck. A thorough evaluation of the fat, skin, muscle, and subplatysmal structures will determine which operation is appropriate to address the patient′s concerns. The fat layer is the most important layer affected by the laser energy, and its removal has the most dramatic effect on the neck and jowl fat compartment. Accurate localization of the fat in either the supraplatysmal or subplatysmal plane is paramount in the treatment of the neck. Pinching the submental fat compartment at rest and then having the patient grimace will help evaluate the position of fat. If the pinched fat volume does not diminish, it is suggestive that the majority of the fat is supraplatysmal; if it does reduce in volume, then there is a significant volume of fat in the subplatysmal plane. Fat that is predominantly positioned in the supraplatysmal plane suggests that laser-assisted liposuction alone will yield a satisfactory result. When there is substantial subplatysmal fat, laser liposuction alone will potentially produce a suboptimal outcome.
The platysma and deep platysmal structures are then evaluated. When an obtuse cervicomental angle is accompanied by platysmal bands at rest or on animation, an open neck approach is generally necessary to create a pleasing neck. Subplatysmal structures need to be evaluated to determine the presence of ptotic submandibular glands. Care must be taken, and the patient made aware, that the glands might become more visible after removal of the supraplatysmal fat alone.
Evaluation of the skin determines the presence or absence of excess skin, the quality of the skin, and the elasticity of the skin. Excess skin, in general, is considered when it extends below the hyoid cartilage. Poor quality skin and lack of elasticity suggest that a full-incision face- and necklift is required for an optimal outcome. Skin that does not extend below the hyoid cartilage and has reasonable quality and residual elasticity responds nicely after laser lipolysis alone.
The jowls are evaluated in relationship to the cervicofacial interface. If the jowl fat pad extends into the neck and there is minimal ptosis of the compartment superiorly at the submalar transition area, then isolated laser lipolysis can be very effective in improving the jawline. When there is significant ptosis of the jowl fat compartment below the jawline with loss of volume at the submalar transition, then an elevation of the jowl fat with or without laser-assisted lipolysis of the jowl fat compartment will give the most favorable outcome.