Injectables and resurfacing techniques: Soft-tissue fillers

Introduction

Facial beauty is in the eye of the beholder; however, facial volume gives the face a characteristic youthful shape and can modify the appearance of what is perceived as beautiful. Indeed it is volume that can connote indicators of youth, symmetry, and even gender differentiation by modulating light and shadows as they fall across the face. Unfortunately, with time soft-tissue descent, ligament laxity, and bone resorption lead to changes in proportion and placement of volume on the face. As a result, there has been historical interest in the use of injected material to modify the contour of skin, underlying soft tissue, and bone. However, effective and safe tools to accomplish such a goal have become available only in recent decades. The plastic surgeon now has access to numerous fillers to soften the stigmata of aging or correct the contour deficits that occur with many disease processes. In order to use these fillers optimally, one must understand the nature of each product.

The goal of this chapter is to present the different classes of fillers and the indications and techniques for their use. Particular attention is paid to the correction of the aging face and techniques for specific areas for enhancement.

The pathophysiology of wrinkles

Prior to augmenting facial skin, it is important to understand the factors that create the aging face. Aging is a complex process, which is the result of both intrinsic (soft-tissue maturation, skeletal change/atrophy, genetics, and muscular hyperactivity) and extrinsic factors (gravity, solar damage, smoking and weight fluctuation). As a result, the smooth curvy appearance of the face is slowly replaced by sharp angles, fine and deep wrinkles, and abrupt hollows and bulges. The anatomy of facial aging is thoroughly reviewed in other chapters in this volume.

With aging, bony changes give rise to a decrease in height and a moderate widening of the facial skeleton. An increased orbital volume, caused in part by an expanding lower orbital rim, results in sunken eyes. This, when combined with an age-related reduction in maxillary height, and nasal resorption leads to a reduced area for the attachment of midfacial soft tissues. The cheeks descend and consequently the nasolabial folds become deeper. The upper lip complex descends (window shade effect), while tear troughs and perioral rhytides appear. If teeth are lost, alveolar height decreases and the chin atrophies. Additionally, the ligamentous attachments of the soft tissues become lax, which further contributes to the appearance of furrows and creases. In the midface, for example, there are seven distinct fat compartments which all change in shape leading to varying aging features. Similarly, we now understand that most major retaining ligaments induce deep facial grooves as the face ages in an inward and downward fashion. Thus, injecting along the line of ligaments can produce projection while injection behind the line of ligaments can create lift.

With age, cell division slows. The epidermis thins out, and the epidermal–dermal junction becomes flatter. The integrity of the stratum corneum decreases and the basal cells acquire more atypia. As a result of these changes, water loss through the skin is increased, leading to drier, more fragile skin. The comparative shrinkage of the more rigid stratum corneum over the deeper and less rigid dermis leads to the classical appearance of wrinkles. These skin depressions are more pronounced in sun-exposed regions and areas that are subject to repeated movements such as face, neck, and hands. Subcutaneous fat atrophy leads to easy bruising and less light reflection which optically also ages the face. The dermis becomes thinner and contains fewer elastic and collagen fibers. Sebaceous glands are less numerous and less active, which also contributes to skin dryness. All the above changes lead to a drier, less elastic, more fragile skin that is more susceptible to gravity and thus wrinkling. It is important to discuss with patients that fillers alone may not achieve their desired aesthetic result and combination treatment with lasers and energy-based devices may also be required. In all cases, topical skincare should not be ignored as skin barrier integrity, hydration and maintenance are key to the end result of soft-tissue filling.

Of course it is also important to realistically set goals of volumization with fillers. For many patients, filler use will not be enough and they are actually facelift candidates. Similarly, many facelift patients over time may need filler as tissue descent is a chronic, lifelong process.

Chronic sun exposure is the most significant environmental factor impacting skin aging. It is responsible for dyschromia, lentigines, telangiectasias, and the loss of the youthful pink hue. Skin texture becomes coarser because the epidermis is thicker in photoaged skin than in normal skin. Overall collagen amount decreases, except in the superficial dermis where there is an area of increased collagen production (grenz zone) representing a chronic inflammatory process known as heliodermatitis. Solar elastosis is pathognomonic of photoaged skin with abundant, degraded, thickened elastic fibers. Lastly, sun exposure contributes to a reduction in ground substance, contributing to deeper folds and wrinkles.

Microscopically, all wrinkles appear like thinned breaks in the dermis. Even though the terms wrinkles, folds, creases, furrows, and rhytides are often used interchangeably, specific features can be used to distinguish between different types of rhytides. Fine wrinkles refer to changes in the texture of the skin that involve the superficial aspect of the dermis. Mimetic wrinkles can extend down to the middle level of the dermis (lines) or down to its full thickness (furrows). These are due to the repeated folding of the skin secondary to the contraction of the facial muscles. As a result, they are perpendicular to the direction of these muscles and occur in locations such as the glabella, periorbita, forehead, and lips. Dynamic wrinkles eventually become static, remaining visible even when the underlying muscle is relaxed.

Folds refer to larger grooves with some level of skin overlap. These are the result of soft-tissue descent secondary to gravity, decreased support, and loss of skin elasticity. Examples include upper eyelid dermatochalasis, nasolabial folds, marionette lines, jowls, and horizontal neck lines. The tear trough is an infraorbital groove that results from soft-tissue tethering along the arcus marginalis between bulging orbital fat above and descending deflated soft tissue below.

The importance of being able to classify wrinkles is central to being able to direct treatment. Superficial lines that course at the upper level of the dermis are amenable to dermabrasion, chemical peels, and lasers. Mimetic wrinkles respond to muscle inactivation with neuromodulators (Botox, Dysport, Xeomin, Jeuveau, and Daxxify) or myotomy/myectomy but can also be improved with the concomitant use of fillers. Finally, fillers are most useful in the treatment of folds, during their early stages, or as an adjuvant modality to surgery, during their more advanced stages. To help guide the physician's treatment and their assessment of improvement, several classification systems have appeared over the years. One of these, the Lemperle classification (see Table 8.2.4 ) is based on wrinkle depth and can be very helpful.

Classification of fillers

Soft-tissue fillers are an ideal option for patients seeking facial rejuvenation with minimal downtime. For the young patient not requiring surgery, these materials offer a viable option, while for older patients, surgery can be combined with fillers and other surface treatments to create an optimal result.

Although the number and variety of products available are impressive, the ideal filler has not yet been found. The definition of an ideal filler may be debatable, but there are certain basic qualities that are agreed upon ( Box 8.2.1 ). Ultimately, even though it is important that worldwide research and development for the ideal soft-tissue filler continues, a balance is needed between embracing new products and ensuring patient safety. In fact, in May 2015, the FDA released a safety communication entitled “Unintentional Injection of Soft Tissue Filler into Blood Vessels in the Face”, which states that:

Unintentional injection of soft-tissue fillers into blood vessels in the face can result in rare, but serious side effects … This can cause vision impairment, blindness, stroke and damage and/or death of the skin (necrosis) and underlying facial structures. … certain injection locations where blood vessel blockage have been reported more often. These sites include the skin between the eyebrows and nose (glabella), in and around the nose, forehead, and around the eyes (periorbital region).

In October 2021 the FDA convened a multidisciplinary panel reviewing the type and incidence of filler complications. They have not issued a final recommendation. The statement also goes on to recommend avoiding the injection of fillers if the level of training and experience is insufficient.

In order to better understand the properties of each product that is either already available or in the pipeline, fillers can be classified into the following categories:

• autologous materials

• biologic materials

• synthetic materials.

Historical perspective

The use of an exogenous material to augment soft tissue can be traced back to Neuber in 1893 who used fat transplanted from the arms to correct facial defects. Later, with the invention of the syringe, Brunning first injected fat in 1911, but significant resorption and fat necrosis depopularized this technique. It was not until liposuction and the concept of micro fat grafting that the use of lipoaspirate for soft-tissue augmentation successfully resurfaced.

Concurrent with the initial efforts to graft fat came attempts to inject other synthetic materials in order to volumize soft tissue. In 1899, Robert Gersuny first injected Vaseline, while later, Eckstein used paraffin to correct fistulas and hernias and to attain aesthetic soft-tissue augmentation. Serious complications such as granulomatous inflammatory reactions (paraffinomas) and nodule formation, embolization, and migration were reported early on, yet paraffin kept being used for over two decades before it was abandoned.

The first reports of the use of silicone date from the end of World War II in Japan when numerous women had their breasts injected with non-medical grade silicone. Shortly after, in 1947, Dr. James Barrett Brown first used silicone for the correction of soft-tissue deficits in the US. Concurrently, hard and rubber silicone found use in creating alloplastic implants. Early flawed animal experiments suggested that injectable silicone was safe, and physicians relied heavily on this improper information. The popularity of the technique led to numerous complications such as lump formation, migration, ulceration, and extrusion. The illicit injection of non-medical grade silicone continues to this day, even though the US Food and Drug Administration (FDA) took a more active role in criminalizing its use in the 1990s. Today, highly purified medical grade silicone oil (AdatoSil 5000, Silikon 1000) is FDA approved for the treatment of retinal detachment and can be used cautiously off-label for volume augmentation.

In 1981, bovine collagen was the first filler approved by the FDA for soft-tissue augmentation; it soon became the gold standard against which all fillers were compared. Its rapid resorption and allergenic nature led to a series of efforts to develop a compound that would not cause allergic reactions and that would last longer. It was not until two decades later that hyaluronic acid (HA) became available for clinical use. HA found multiple medical uses before it was approved in the US as a soft-tissue filler. HA dermal fillers rapidly replaced collagen as the gold standard in cosmetic soft-tissue augmentation.

The high demand and success of HA products led to an intense search for products that are similar to HA, which did not cause hypersensitivity reactions, but are longer lasting. This in turn led to a number of newer and longer-lasting products such as poly- l -lactic acid (PLLA: Sculptra, FDA approval in 2004 for HIV-related facial lipoatrophy; Galderma Laboratories, FDA approval in 2009), calcium hydroxylapatite (Radiesse, FDA approval in 2006), and polymethylmethacrylate (PMMA)/polyacrylamide products such as Bellafill (previously Artefill, FDA approval in 2006). Today, plastic surgeons have in their armamentarium numerous safe fillers that can produce unprecedented aesthetic results, provided that they are used in an educated/safe manner.

Injection technique

Before using injectable fillers, anesthesia of the areas to be treated should be considered. Nerve blocks, such as mental, infraorbital, and supraorbital/supratrochlear, work well and provide analgesia to large areas of the face. Direct infiltration of the area with lidocaine is another option, but this could lead to distortion of the anatomic structure to be corrected, and thus potentially to over- or undercorrection. The inclusion of epinephrine in the infiltration can potentially decrease bruising. Currently almost all fillers contain lidocaine so it is important to ensure that patients do not have a lidocaine allergy prior to use. Additional lidocaine with epinephrine can be admixed with fillers as a way to dilute them, but keep in mind that epinephrine can blanch areas of injection which can mask vascular compromise.

The needle used for injection largely depends on the viscosity of the product injected. Less viscous HA products are injected with 30–31 G needles. More viscous HA products can be slowly injected through either a small needle such as a 30 G or a larger 28 G needle with more ease. Radiesse usually requires a 28 G needle, as does Voluma, while Sculptra and Bellafill, which are among the most viscous products injected, require at least a 26 G needle. Injection is usually in an anterograde or retrograde fashion, as the needle is advanced or withdrawn, respectively. Anterograde technique can be helpful in areas where soft fluid filler product ballottes the subcutaneous tissues away to decrease the risk of vascular injection.

The injection technique can vary from simple linear threading and the deposition of a small aliquot to more complex methods such as serial linear threading, radial fanning, cross-hatching, and serial puncture deposition. These techniques are used in combination depending on the location to be treated.

The linear threading or tunneling technique involves injection either intradermally or into the subcutaneous level ( Fig. 8.2.2A ). Once the needle is inserted, the product is injected in a retrograde or anterograde fashion. Linear threading is most commonly used to correct wrinkles and furrows. However, when deeper creases are treated, multiple parallel linear threads at different levels have to be used to accomplish the desired volumetric augmentation ( Fig. 8.2.2C ). Examples of where this technique is commonly used include the glabellar lines, the nasolabial folds, the lips, and the tear trough, among others.

Radial fanning is a variation of the linear threading technique ( Fig. 8.2.3A ). Just before the needle is completely withdrawn from the skin, it is reinserted in a different direction and the product is again injected in a retrograde fashion. This process is repeated multiple times in different directions until adequate correction is accomplished. This approach is particularly useful in malar augmentation, but it is also used in the correction of the prejowl sulcus and the nasolabial fold.

Cross-hatching is often used in the correction of large surface areas such as the marionette lines/prejowl sulcus or the hollowing of the lower cheek ( Fig. 8.2.3B ). Two independent radial fanning injections oriented perpendicular to each other constitute also a form of cross-hatching and are commonly used in cheek augmentation.

Frequently the needle is inserted deep into the tissue and an aliquot of product is laid down; this is known as the depot or droplet technique ( Fig. 8.2.2B ). Large volumes deposited in this fashion can lead to palpable nodules and irregularities. Usually small droplets are deposited in a serial fashion; this is known as the serial puncture technique. These aliquots have to be close together to prevent irregularities. If any irregularities appear they can be managed by massaging. This technique is frequently used for tear trough correction and in lip augmentation, but also in the treatment of all other wrinkles and creases. Experienced injectors often use combinations of all of these techniques.

Some practitioners recommend the use of blunt-tipped microcannulas. Many authors describe their experience of decreased bruising, especially when using a fanning injection technique.

Microcannulas have gained tremendous popularity in recent years due to a perceived decrease in risk of vascular occlusion. This author cautions against relying on the blunt tip as cannula gauges even at 25 G can pop an inflated balloon. Knowledge of anatomy is central to injecting anything in the face, whether with a needle or a cannula. It is not clear if cannula use more precisely deposits product and prevents its migration compared to a needle. Use of the instrument to place fillers is ultimately a personal preference of the injector though cannulas are becoming more common as one needs only to introduce the cannula through a single puncture hole to be able to reach several areas for filler.

Indications and applications

There are multiple indications for the use of dermal fillers. Below is a list of the most common areas of the aging face usually addressed with injectables. The appropriate types of fillers for each area, as well as some technical nuances for their optimal application, are also described.