INTRODUCTION
When used appropriately, injectable dermal fillers are an excellent tool for facial rejuvenation and are currently the second most common nonsurgical cosmetic procedure. , Fillers offer significant facial rejuvenation advantages with minimal invasiveness and downtime. Injectable fillers can enhance and balance facial features, improve fine and deep facial rhytids, and reverse volume loss often associated with aging. This chapter will delve into the various types of filler, discuss indications and applications, summarize techniques and protocols, and identify and manage complications.
The goal of maintaining a youthful appearance is timeless. Attempts for facial augmentation trace back to the late 1800s, starting with liquid paraffin, liquid silicone, and autologous fat injections, which were subsequently abandoned due to frequent complications of migration, embolization, granulation formation, inconsistent results, unpredictable longevity, and occasionally disfiguring inflammatory responses. , In 1981, the first bovine collagen injection, Zyderm, became Food and Drug Administration approved as a dermal filler. Since then, there has been an explosive evolution and expansion in filler products, with a wide range of materials, including hyaluronic acid (HA), calcium hydroxylapatite (CaHA), poly-L-lactic acid (PLLA), polymethylmethacrylate (PMMA), and silicone. Bovine collagen is rarely used in clinical practice now due to its short duration.
Facial proportions are typically discussed using vertical fifths and horizontal thirds ( Fig. 29.1 ). We previously published using facial anatomic subunits (FASA) as an additional tool for facial analysis ( Fig. 29.2 ). Understanding these subunits helps practitioners select procedures that enhance a patient’s appearance naturally and attractively. This knowledge is particularly useful when using fillers to achieve authentic, natural, and undetectable results safely. ,
Facial proportions using vertical fifths and horizontal thirds. The horizontal thirds are measured from trichion to glabella, glabella to subnasale, and subnasale to menton.
(Reproduced with permission from Rebecca Fitzgerald, Chapter 3- Addressing Facial Shape and Proportions With Injectable Agents in Youth and Age, Editor(s): Babak Azizzadeh, Mark R. Murphy, Calvin M. Johnson, Guy G. Massry, Rebecca Fitzgerald, Master Techniques in Facial Rejuvenation, 2nd Edition, Elsevier, 2018.
Facial anatomic subunits are regions of the face with similar surface topography and three-dimensional qualities, determined by underlying structures, craniofacial skeletal modeling, fat compartments, skin thickness, muscle activity, and curvature.
(Reproduced with permission from the Center for Advanced Facial Plastic Surgery. Image adapted from Rebecca Fitzgerald, Chapter 3: Addressing Facial Shape and Proportions With Injectable Agents in Youth and Age. Editor(s): Babak Azizzadeh, Mark R. Murphy, Calvin M. Johnson, Guy G. Massry, Rebecca Fitzgerald, Master Techniques in Facial Rejuvenation (Second Edition), Elsevier, 2018, Pages 15-54.e2, https://doi.org/10.1016/B978-0-323-35876-7.00003-0 .)
TYPES OF FILLERS
While fillers aim to improve rhytids or volume loss, there are critical differences in their formulations and mechanisms of action. HA fillers are the most widely used in clinical practice and are known for their excellent safety profile and long-lasting duration. They offer numerous options, giving practitioners flexibility depending on the treatment location. Additionally, HA fillers are the only reversible type, allowing for adjustments to achieve the desired aesthetic outcomes. Structurally, HA is a highly hydrophilic polysaccharide made of glycosaminoglycans normally found in extracellular matrixes. With variable crosslinking technology, each HA filler can have varying molecular weight, density, and gel properties. For example, Restylane Fynesse 0.1% to 5% crosslinking is more suited for fine to medium rhytids and lip submucosa, and Restylane Defyne with 8% crosslinking is more suited for moderate to severe rhytids and application to cheek and jawline.
HA fillers are characterized by their viscoelastic properties and resistance to deformation, which is important for injectability, lifting capacity once injected, and product migration from site of injection. Clinically, deformation can be inflicted by sheer stress from facial movements, from speaking, eating, and smiling. By being viscoelastic, HA fillers display both viscous (irreversible) and elastic (reversible) deformation responses to a force. , Resistance to deformation (G*), elastic modulus (G′), viscous modulus (G″), and phase angle (δ) are terminologies to describe these properties. , A gel that is more elastic in character (low δ) will deform when dynamic shearing forces are applied and recover its original shape once shearing forces are removed. A gel that is more viscous (high δ) is less likely to return to its initial shape, thereby being more likely to migrate.
HA fillers are also described by their cohesive properties. Cohesion describes the internal forces that unite the solid or liquid phases but is challenging to measure. A cohesive gel remains monophasic in an aqueous solution (such as saline). It may be more likely to aggregate into clumps or “bunch up,” while also less likely to fragment, migrate, or dissolve once injected ( Fig. 29.3 ). A gel with a higher G′ is “stiffer,” with more cohesivity and resistance to enzymatic degradation. Examples of these stiffer gels include Juvederm Volux (G′ = 307 Pa) and Restylane Defyne (G′= 260 Pa). On the other hand, a gel with a lower G′ is “softer” and may be more suitable for finer corrections but also more readily degraded. Examples include Juvederm Volbella (G′ = 150 Pa) and Restylane Fynesse (G′ = 10 Pa).
Schematic relationship between gel viscosity and cohesivity.
(Image adapted from Molliard SG, et al. Key rheological properties of hyaluronic acid fillers: from tissue integration to product degradation. Plast Aesthet Res. 2018;5:17.
Skinvive is a HA characterized by its low G′ (10 to 20 Pa) and a high viscosity (δ approximately 70 to 80 degrees), facilitating an even distribution to the skin’s surface. Unlike traditional fillers, which are injected into the dermis to compensate for volume loss, Skinvive is administered superficially, functioning primarily as a hydration enhancer rather than a volumizer. By leveraging the moisture-attracting properties of the HA, Skinvive improves skin hydration and texture. Understanding the viscosity and cohesivity of HA fillers and the relationship between the two properties will aid in the proper selection and precise placement of the products.
Historically, most HA fillers were believed to have a duration of less than one year. However, recent studies and clinical experiences have shown that these fillers may persist for much longer period of time. Consequently, repeated injections may not be necessary and could potentially result in undesirable outcomes, such as inflammation, migration, and an “overfilled” appearance. It is crucial to administer repeat treatments only when genuinely needed.
Biostimulatory injectables stimulate the body to produce its own collagen. These include CaHA and PLLA fillers. CaHA acts as both a filler and a collagen stimulator. It is generally thicker in consistency and has a long duration of about a year. The only FDA-approved CaHA is Radiesse, commonly used to improve facial volume loss and hand rejuvenation. PLLA is a collagen stimulator that does not immediately impact facial volume. It uniquely has a gradual onset and is longer lasting, which is important to take note of to avoid overcorrection. Sculptra is the only FDA-approved PLLA, which is particularly indicated in treating advanced facial volume loss and lipoatrophy in individuals with HIV.
Unlike the temporary fillers, the results associated with PMMA, silicone, and autologous fat transfers can last for many years. Permanent fillers should likely not be used by practitioners who are not experienced with them because improper administration can lead to irreversible complications and adverse outcomes.
Currently, Bellafill is the only FDA-approved PMMA for treating acne scars and nasolabial folds. Bellafill differs from earlier PMMA products primarily in its formulation and safety profile. It consists of uniform, smooth PMMA microspheres suspended in a collagen gel, which provides immediate volume and stimulates long-term collagen production. Earlier PMMA products often lacked such uniformity and refinement, leading to higher risks of complications such as granulomas and uneven results. Its formulation provides better biocompatibility, longevity, and a reduced risk of adverse reactions, making it a more reliable option for long-lasting facial rejuvenation. As a nonbiodegradable substance, PMMA does carry higher rates of allergic reactions, material migration/extrusion, and the need for surgical excision.
Silicone, used as a filler since the 1960s for breast augmentation and later for facial procedures, has long been controversial due to its potential for severe complications, such as granulomas, migration, and chronic inflammation. Silicone should never be injected like traditional fillers but instead is used with the microdroplet technique, involving tiny amounts injected in multiple sessions to gradually build volume and shape. This method helps avoid overuse and minimizes adverse effects. Ideal locations for silicone injections include areas requiring fine contouring, such as the cheeks and nasolabial folds. The only FDA-approved silicone filler product is Silikon 1000, used off-label for facial rejuvenation but officially approved only for retinal detachment and certain ophthalmic conditions. Unlike FDA-approved products, nonapproved silicone fillers can vary significantly in purity and consistency, increasing the likelihood of adverse reactions and long-term complications. Due to its complexities, silicone should only be injected by experienced practitioners to ensure natural-looking results and minimize adverse events.
Autologous fat transfer is an ideal option for patients who require significant volume augmentation, prefer not to use synthetic materials, and are undergoing other surgical procedures. Patients who also have had prior issues with HA fillers may choose fat grafting. It can be performed as a stand-alone procedure under local anesthesia or combined with blepharoplasty and rhytidectomy. Fat grafting can feel natural and soft and be readily harvested via liposuction from the abdomen, flanks, thighs, or gluteal region. While autologous fat grafting has an ideal textural feel and durability, it can have an unpredictable volume retention rate regardless of the method of harvesting and processing. , One randomized controlled study treating HIV-lipoatrophy patients reported retention rates of 31% to 61% in the autologous fat group versus 80% to 87% in the HA group at 12 months. Autologous fat transfer is a surgical procedure that the surgeon and patient must take much more seriously. Studies have demonstrated a higher rate of short-term adverse events compared to HA fillers but show no significant difference in outcomes at 12 months.
INDICATIONS AND APPLICATIONS
Facial fillers have a plethora of applications in facial rejuvenation and augmentation. An in-depth, composite understanding of facial anatomy and morphologic changes with aging is critical. With facial aging, there is superficial skin laxity, thinning, and textural changes, fat compartment atrophy, and facial skeleton resorption and remodeling. Proper application of fillers requires knowledge of these anatomical changes to achieve optimal, natural-looking results ( Fig. 29.4 ).
Pre- and post-injection photographs of a female patient ( above and below , respectively). A naturally youthful and balanced full facial rejuvenation was achieved using HA filler.
(Photographs courtesy Babak Azizzadeh, MD FACS, Center for Advanced Facial Plastic Surgery.)
While it is essential to address the entirety of an aging face for natural results, the upper third of the face is notably at the highest risk for complications with fillers because of the vast anastomotic vascular network ( Table 29.1 ). Here, the supratrochlear and supraorbital arteries present deeply at the inferior aspect of the superior orbital rim and extensively branch, becoming more superficial closer to the hairline. Laterally, the superficial temporal vessels are present. With aging, volume loss and bony remodeling can lead to significant temple hallowing and lower forehead and eyebrows flattening. Subcutaneous HA filler injections may be used to elevate the tail of the brow. In lateral brow and temple augmentation for hallowing, filler may be carefully injected in a supraperiosteal plane. It is crucial here to aspirate using needles before injecting to avoid the superficial and deep temporal vessels. The forehead and glabella are now generally avoided due to higher complication risks.
Table 29.1
Facial Areas and Associated Injection Risk Levels
| Risk | Injection Area |
|---|---|
| Very high | Glabella, nose, and forehead |
| High | Temples, nasolabial folds, tear troughs, periorbital region, medial cheek (between mid-papillary line and side of nose) |
| Moderate | Lips, perioral region, anterior cheek (between a vertical line through the lateral canthus and mid-pupillary line) |
| Low | Jawline and marionette lines, lateral cheek (lateral to vertical line through lateral canthus), malar prominence, preauricular, chin |
Adapted from Goodman GJ, Magnusson MR, Callan P, et al. A Consensus on minimizing the risk of hyaluronic acid embolic visual loss and suggestions for immediate bedside management. Aesthet Surg J . 2020;40(9):1009–1021.
The periorbital region often shows the earliest and most significant signs of facial aging. In addition to skin and subcutaneous fat changes, there is significant bony resorption of the orbit. In females, classically this occurs medially at the superior rim and laterally at the inferior rim; in males, this occurs in the whole inferior orbital rim. This contributes to an upper eyelid A-frame deformity and sunken eye appearance. Further aging changes occur, as the ligaments, such as Lockwood’s, lose structural support, leading to protrusion of upper nasal and lower orbital fat pads. Pseudoherniation of lower orbital fat pads becomes even more prominent as the midface fat compartments atrophy and descend. Injection here is ideally deep to the orbicularis oculi muscle and superficial to the periosteum, with care to avoid the sensory nerves and infraorbital and angular arteries.
Fat volume loss and descent of the superficial, deep medial, nasolabial, and buccal fat pads and the bony regression in the inferior orbital wall, pyriform aperture of the maxilla also promote the concavity and deepening of the midface appearance. The injection approach for volume restoration in this area should remain deep and perpendicular to the angular vasculature to avoid cannulating the artery. The ideal depth for cheek filler is in the sub-SMAS or supraperiosteal plane. Superficial injections for fine lines should be deep dermal or dermal-subcutaneous. The injector should take care of the facial artery and the dense vascular branching in this region.
In addition to the nasolabial folds, the nose itself has significant age-related changes. The nasal tip becomes droopy or ptotic as the alar cartilages weaken and flatten. The intercartilaginous ligaments and fibrous attachments weaken, further contributing to tip ptosis. The change in tip rotation and projection can create a dorsal hump, supratip fullness, and broader nasal base. As the nasal skin thins, the underlying nasal cartilages and bone become more visible. Especially in recent years, fillers can be used as a nonsurgical rhinoplasty as an effective, minimally invasive, and temporary option to augment the nose. HA filler is commonly used (96.76%), followed by CaHA (1.22%). Dermal filler can successfully correct the nasofrontal angle in patients with an excessive nasal hump or under projected dorsum. While generally low risk, it is important to note the rare risk of skin necrosis and blindness if a vascular complication occurs.
Whether it is for cosmetic augmentation or age-related rejuvenation, the lips are one of the most common areas injected. Filler can be used to augment the Cupid bow or achieve lip fullness and symmetry ( Fig. 29.5 ). In a study evaluating 700 expert opinions on the ideal upper to lower lip ratio, most participants chose the 0.85:1 ratio. The superior and inferior labial arteries from the facial artery are approximately 1.5 mm superolateral to the oral commissure, with variations in depth (intramuscular or deep or superficial to the orbicularis oris muscle). The general rule to avoid encountering these vessels is to maintain needle depth to 2.5 mm or less around the vermillion border. Whether injecting with needle or cannula, it is important to inject slowly in a retrograde manner. While product selection varies by the proceduralist, the relatively “softer” HA fillers, with a lower G′ and density, are ideal for producing a naturally volumized cosmetic outcome. In normal-volume lips with an adequate preexisting volume and vermillion border definition, about 1.0 to 1.5 mL filler is injected with a reassessment in a couple of weeks. In thin lips with inadequate volume, multiple treatment sessions may be needed to achieve the goal volume while respecting the natural limited expansion properties to maintain a natural appearance. Generally, the technique is to achieve the patient’s ideal upper-to-lower lip ratio prior to achieving the targeted lip volume. To address thin aging lips, it is important to address the combination of lips and perioral lines. Some authors recommend more judicious injections with more serial sessions. , For individuals with very long upper lips due to aging, a lip lift is often necessary to achieve a natural and youthful appearance, as fillers alone cannot adequately shorten the upper lip ( Fig. 29.6 ). Attempting to improve aesthetics with fillers alone in these cases can result in an unnatural and problematic look, often creating an overly filled and distorted appearance.
