Chapter 254. Soft Tissue Augmentation

Soft-tissue fillers (Table 254-1) are either injected through a sharp needle or through a blunt cannula. The level of injection into the skin and the chosen length of the needle depend on the type of filler injected, the properties of the filler, the area injected, and the desired result. Threading is a technique in which the needle is inserted into the skin and the filler is deposited in a linear fashion along the track of the needle as it is being withdrawn. Fanning is a type of threading in which, instead of inserting the needle into a new area each time, the needle is just withdrawn so that a new track can be made radially adjacent to the last. In the “push-ahead” technique, an injection is made in an antegrade direction, so that the injectable material flows from the tip of the needle and hydrodissects the tissues as it flows. This technique is often used in areas in which bruising is more likely to occur along the needle track, such as the upper lid and brow. In the depot method of injection, small “pearls” of material are deposited serially, usually along a fold or deep by bone. Cross-hatching is an approach used to diffusely cover an area with the injected material. In this method, linear threads are lined up in succession and a second series of rows is then layered at right angles on top of the first. Figure 254-1 illustrates the different injection techniques. In addition to the methods just described, highly viscous fillers emerging on the US market will most likely be injected in a deep subcutaneous bolus through a blunt cannula or large bore needle. Whatever the technique chosen, care should be taken in highly vascular areas to avoid intravascular injection of filling material. The plunger of the syringe should be pulled back to check for blood flow, and if it is found, the needle should be withdrawn and repositioned.

Once considered the “gold standard” of dermal fillers, collagens (bovine, human, and porcine) are no longer available on the US market.

Patient Selection

Hyaluronic acid–derived fillers are a good choice for patients who desire a long period of correction or more volume enhancement. They are approved for augmentation of the nasolabial fold, but other common areas of treatment include the labiomental crease, lips, cheeks, and periorbital areas. Patients often feel that the hyaluronic acid fillers are softer and more natural in appearance than the collagens were, but they need to be warned about the risk of increased erythema, edema, and bruising associated with these products.

Formulations

Hyaluronic acid (HA) is a polysaccharide that is homologous throughout the animal kingdom. Injectable FDA-approved forms include non–animal-derived stabilized hyaluronic acid products (NASHA) made through a bacterial fermentation process and an avian-derived version isolated from cocks’ combs. Brands of injectable hyaluronic acids differ not only in their derivation but also in their concentration of hyaluronic acid per milliliter of product, type of cross-linking or stabilizing agents, viscosity, and particle size. Some hyaluronic acid products exist as biphasic gels containing both crosslinked and uncrosslinked particles and some as monophasic gels containing only crosslinked particles. The biphasic NASHA products are made en bloc initially and then passed through a sieve to create particles ranging in size from 10,000 per mL to 100,000 per mL with a hyaluronic acid concentration of 20 mg/mL. The smaller particle size permits injection through smaller-gauge needles into finer wrinkles and the larger particle size is best for volumetric filling. The small amount of non-cross-linked HA allows for smooth flow with low injection pressures. Monophasic hyaluronic acid gels are produced by varying the amount of high- and low-molecular weight hyaluronic acid producing a hydrogenous gel. The monophasic product is available in two formulations, one containing 24 mg/mL of hyaluronic acid and one containing 30 mg/mL of hyaluronic acid. The crosslinking agent used in both the mono- and biphasic products is BDDE (1,4 butanediol diglycidyl ether). The avian derived hyaluronic acid, contains 6 mg/mL of hyaluronic acid highly cross-linked with divinyl sulfide. All hyaluronic acid products are prepackaged in filled syringes that require no refrigeration.

Anesthesia

Due to their high viscosity hyaluronic acid products can cause significant discomfort on injection so most hyaluronic acids are available combined with lidocaine. Topical anesthetic can also be applied before injection. This usually results in adequate anesthesia for periorbital, nasolabial fold, and labiomental crease injections; however, if lips or perioral rhytides are being treated, an ancillary local infiltration of 1% lidocaine or segmental nerve block may be indicated.

Technique

Hyaluronic acids should be injected with the patient in a position that elicits the defect or creases to be treated and offers ease of injection to the operator. This is best accomplished by reclining the patient to a 45° angle. All the hyaluronic acid products come with a needle in the gauge of choice for ease of injection and preservation of the physical properties of the gel. Due to their viscoelastic properties, however, hyaluronic acids can often be injected through needles tailored to the area or level of injection. For instance, a 32-gauge needle allows for more precise injection of vertical lip rhytides and a 1½ inch needle may facilitate injection into distal sites. Hyaluronic acids are injected in most areas via threading, depot, or fanning. They are particularly amenable to cross-hatching in areas in which a greater density of augmentation is desired. In particular, when hyaluronic acid is injected into the nasolabial fold it is important to span the width of the fold with a serial threading technique and then crosshatch at right angles. This gives structural integrity to the fold and prevents the undesirable result of merely moving the fold medially. In addition, it is often necessary to “suspend” the fold by augmenting the cheek. This is usually done with a deep bolus injection of a high density HA. The labiomental crease can be injected similarly to the nasolabial fold, again blending the product so as not to move the fold medially. Lip injections are made using a depot or threading technique, either along the vermillion border, in the body of the lip, or in a combination of both. Perhaps one of the most exciting off-label applications of hyaluronic acids is the correction of tear trough deformity or suborbital hollows. Injections are made either under the orbicularis oculi muscle near the orbital bone or subdermally above the muscle. Intramuscular injections are to be avoided since the movement in this area increases the risk of lumping of the product. A depot method of injection is preferred in which very small amounts of hyaluronic acid are deposited on each pass, but threading can also be helpful to ensure even blending into neighboring areas. The push-ahead technique is preferred for the sub-brow area. After injection the periorbital area should be vigorously massaged to disperse the product and minimize aggregation of gel particles. Although periorbital injection of hyaluronic acid results in high levels of patient satisfaction, it is an advanced injection method best left to those with the greatest injecting experience.

Postprocedure Instructions

The application of ice immediately after the procedure and periodically throughout the day is recommended after the injection of hyaluronic acid. Patients are instructed to avoid manipulation of the treated area and extremes of temperature for the first 48 hours after injection. If the lips were treated in a patient with a history of cold sores, then an antiviral medication should be administered prophylactically on the day of the procedure. Patients are instructed to return to the office if they experience any problems such as redness, purulence, or nodule formation.

Unique Complications

Most complications result from improper application of the product. Placement of this clear gel too superficially results in a blue discoloration. Placement of too large an aliquot can result in a noninflammatory bump. Most ill-placed hyaluronic acid can be released by incising with a 20-gauge needle and expressing the material. Hyaluronic acid products also contain small amounts of impurities that can cause hypersensitivity reactions. Patients can react to sterile bacterial proteins or avian proteins by forming sterile abscesses or granulomatous inflammatory nodules. It has been shown that these nodules, which appear clinically to be granulomas, may in fact be small foci of infection. Treatment with an antistaphylococcal antibiotic is the initial treatment of choice. If no resolution occurs, dilute intralesional corticosteroids can be administered, or hyaluronidase can be injected to cause rapid dissolution of the product.1

Longevity

In general, the longevity of augmentation is greater for the more highly cross-linked or stabilized forms and increases with increasing viscosity and particle size. Hyaluronic acid–based products are broken down via isovolemic degradation; they maintain a constant volume throughout their degradation because of their ability to bind water. This property makes possible a very long-lasting product.

In a double-blind multicenter study, the biphasic hyaluronic acid gel was found superior to bovine collagen at al postinjection time points. At 6 months, 67.2% of collagen-treated folds had returned to their baseline severity, as opposed to only 29.9% of hyaluronic acid–treated folds.2 In a study comparing large particle biphasic NASHA to avian derived hyaluronic acid, at 6 months after treatment, the proportion of patients showing improvement in the Wrinkle Severity Rating Scale score of the nasolabial folds was higher in the group treated with the NASHA product (75%) than in the group treated with the avian product (38%).3 In a head-to-head study comparing the tolerability and efficacy of small particle biphasic NASHA versus avian hyaluronic acid in the treatment of nasolabial folds, the NASHA product demonstrated higher efficacy and patient satisfaction ratings than the avian product at 12 weeks.4 The bi- and monophasic NASHA products last up to 12 months quite consistently. To this date, no head-to-head studies between these products has been published. Figure 254-2 shows a 35-year-old woman before and after treatment of the nasolabial folds with a NASHA gel.

Patient Selection

Poly-L-lactic acid is FDA approved both for the treatment of lipoatrophy associated with human immunodeficiency virus (HIV) infection and for the cosmetic correction of shallow-to-deep contour deficiencies. Currently in the United States, PLLA is gaining popularity as a no-downtime, long-lasting filler with a wide range of applications. PLLA's uniqueness lies in the fact that it is not a direct filling agent but rather a biostimulatory agent, eliciting tissue thickening over the course of many months and many treatment sessions. It is therefore the ideal filler for someone desiring a gradual, subtle change. Because PLLA works by initiating a foreign-body tissue response, it is not suited for patients taking immunosuppressive or anti-inflammatory drugs, and it appears to work most efficiently in younger patients. PLLA can be used for volume enhancement in the nasolabial fold, labiomental crease, chin, jawline, buccal hollows, and temples. Some practitioners have found it to provide good filling for the dorsum of the aging hands but in this area there is a moderate risk of nodule formation. It is not recommended for use in the lips and should be used with care in the periorbital area.

Formulation

PLLA is the same substance used in the formulation of absorbable suture material and is biocompatible and biodegradable. It is supplied in a glass bottle as a lyophilized powder containing carboxymethylcellulose as an emulsifier and mannitol as an osmotic agent. Injection of PLLA on repeated occasions presumably initiates an immune response that eventually leads to fibroblast activation and collagen deposition. High-level ultrasonographic images taken before and after a series of treatments in study patients confirms the presence of a zone of dermal thickening, but the exact mechanism is unknown.

Anesthesia

PLLA must be reconstituted at least 2 hours in advance of use; however, current standard of care is reconstitution at least 8 hours before treatment to fully suspend and hydrate the particles of PLLA. The package insert recommends reconstitution with 3–5 mL of sterile water, but the consensus of physicians currently using the product is to reconstitute with 5 mL of diluent at a minimum. It is therefore possible to reconstitute the product in advance with 4 mL or more of sterile water and immediately before injection to add 1 mL of 1% lidocaine to the bottle. This tempers the pain on injection. In addition, patients may want to apply a topical anesthetic containing either 4% lidocaine or 20% tetracaine in advance of treatment.

Technique

Because of the diffuse panfacial nature of PLLA injections, it is helpful to inject the patient in a supine position. PLLA is injected through a 25- to 26-gauge needle. Because of the risk of particle clumping, the bottle must be agitated frequently throughout the course of treatment. The operator must maintain maximum control over injection amounts, so drawing the material up into 1-mL syringes is highly recommended. The injection technique used when infiltrating PLLA is diffuse crosshatching and threading. Depot deposition of product is no longer recommended. The principle is to inject PLLA into areas that will eventually display a direct impact from local volume change or affect neighboring areas by filling and suspending tissues upstream. Lower-face injections are performed diffusely over a wide surface area and involve the placement of 0.1-mL linear threads of solution 2 mm apart. The recommended technique is to inject across folds to distend them, rather than filling them directly. No attempt at volumetric correction is made during treatment; rather, the intent is to place the PLLA solution diffusely. The level of injection in the lower face (cheek, nasolabial fold, jawline, labiomental crease, chin) is subdermal. In the upper face (temples and periorbital area) treatment is via diffuse threading of 0.05 mL of PLLA solution under or close to periosteum. No more that 0.5 mL total should be distributed in this fashion. If clogging of the needle occurs, it should be withdrawn and either changed or cleared before proceeding. Many practitioners have found that the use of long needles (1½ inch) better facilitates even dispersion of the product.

Postprocedure Instructions

Immediately after injection, treated areas must be vigorously massaged to distribute the suspension evenly into the tissues. No blebs of material should be palpable. When the practitioner is satisfied that this is the case, the massage may then be continued in a gentler manner by an assistant for the next 5 minutes. Ice is then applied to the face for 20 minutes. The patient may then apply makeup and resume normal activities. The patient must massage the areas of injection for 5 minutes, 5 times a day for 5 days. Because minimal augmentation is achieved in each session, patients are instructed to return at 6-week intervals for additional treatments. The motto “Treat, wait, assess” is an important one to follow when using PLLA. Resultant augmentation can take 4 months or longer to occur, so patience is necessary to avoid overcorrection. For the average patient with cosmetic concerns, between three and six treatments will be required for ample augmentation to occur (Fig. 254-3). For patients with severe lipoatrophy, a minimum of six sessions will be required, often with injection of two vials per session.

Unique Complications

Superficial injection of PLLA most often results in visible papule formation. Reconstitution with inadequate amounts of fluid may also increase this risk. Delayed formation of subcutaneous papules has been reported in the literature. These palpable papules are most often nonvisible, asymptomatic, and noninflammatory, and require no treatment. If they are of concern to the patient, an attempt can be made to break apart the papules by injecting sterile water into them or by teasing them apart with a 27-gauge needle. Results of an 8-year injectable filler safety study found evidence to support a decreased risk of nodules with increasing dilutions.5 Rarely large visible nodules can be seen as a late-onset side effect. Intralesional cortisone may be of help since they are often inflammatory or granulomatous in nature. Surgical removal is also an option for large unresponsive or deforming nodules.

Longevity

The results from PLLA infiltration are thought to last 2 years or longer, with gradual resorption and breakdown of the product to lactic acid over the course of 2–3 years.

Patient Selection

Patients requiring augmentation of the nasolabial folds, labiomental crease, mandibular ramus, cheeks, or prejowl sulcus are candidates for treatment with calcium hydroxylapatite (CaHA). CaHA has also been used with success in the correction of atrophic acne scars, in the recontouring of nasal defects, and in nipple reconstruction after failed nipple areolar reconstruction. Due to the risk of lump formation, CaHA is not recommended for lip augmentation and should be used judiciously in the periorbital area.

Formulation

Originally approved for use by the FDA as a radiographic marker and for the correction of oral and maxillofacial defects and the treatment of vocal cord insufficiency, CaHA has recently gained approval as a nasolabial fold filler. All other areas mentioned above are common off-label uses. The microspheres of CaHA, once injected into the deep dermis, form a scaffold to support the growth of autologous collagen so there is overlap with this product as not only a temporary filler, but also as a biostimulatory agent. CaHA microspheres are suspended in a polysaccharide carrier, which holds the microspheres in place until it is resorbed and neocollagenesis takes place. CaHA contains no animal or human tissues, so allergy testing is not indicated.

Anesthesia and Technique

Injection of CaHA is quite uncomfortable, so it is almost always necessary to anesthetize the area first with 1% lidocaine. A current popular practice is to mix 0.2 cc of 1% lidocaine with the CaHA via a female-female adapter. This not only provides adequate anesthesia but also thins the product to allow for smoother injection. Due to its viscosity CaHA must be injected through a 27- to 28-gauge needle. Placing the patient in a supine or at 45 degrees, a threading technique is used, with infiltration staying at the dermal–subcutaneous junction in the area of the nasolabial fold and at the deep fat or supraperiosteal region in the areas of the cheek and mandible. CaHA appears to work best if patients undergo retreatment or touchup at 3 months.

Postprocedure Instructions

There can be marked swelling and bruising after the injection of CaHA, so post-treatment icing is recommended. Many physicians advocate immediate postinjection massage but feel that continued massage is unwarranted.

Unique Complications

The majority of complications with CaHA (nodules) are seen in the lips, but it is possible for nodules lasting 1–2 years to occur anywhere the substance is injected. There is a paucity of studies of the use of CaHA for soft-tissue augmentation. One small study noted a 3% nodule rate in 29 patients treated with CaHA for soft-tissue augmentation. Nodules are supposedly noninflammatory, and often the material can be extruded from a puncture incision. Persistent nodules may have to be surgically removed. If CaHA is injected too superficially or at appropriate levels in thin skin, its opacity can be seen. Demarcation of product is especially evident in the periorbital area, as is prolonged erythema.

Longevity

In a 12 month, multicenter prospective randomized split face trial comparing CaHA to NASHA in the nasolabial folds, CaHA was found to provide significantly greater correction at all time points. In practice, though, longevity appears variable, with effects lasting from 6–18 months.6

Patient Selection

Autologous fat transfer (AFT) is a practical option for those patients desiring a more dramatic global change in facial appearance. Recent anatomic research suggests that facial fat is delineated in discreet fat compartments that change morphologically over time.7 Therefore, using fat as a filler is done with the intent of restoring the youthful architecture to these fat compartments. This provides broader rejuvenation to the aging face affected by volume loss. Fat is a versatile filler, effective in the periorbital area as well as the lips. Because it is autologous, it is the filler of choice for patients with collagen vascular disease or proven allergic reactions to collagens or hyaluronic acids. AFT is a more involved surgical procedure than the injection of the other fillers previously discussed. Exclusion criteria for treatment include concomitant anticoagulant treatment and poor health.

Technique

Preparation and Anesthesia

For 2 weeks before the initial AFT procedure, the patient must stop taking all nonsteroidal anti-inflammatory drugs, vitamin E, ω-3 fatty acid supplements, and ginkgo, ginger, or ginseng supplements. The patient is instructed to begin therapy with an appropriate antistaphylococcal antibiotic starting the day before procedure. On the day of the procedure, the donor fat site and the face are both washed with an antibacterial soap. The physician then delineates the area to be suctioned with a marking pen. Every attempt should be made to choose a donor site that benefits a patient aesthetically. The outer thighs and hips in women and the flanks in men are usually good sites for fat harvesting.

In preparation for fat transfer, a pattern is drawn on the face delineating the areas in which fat is to be placed and highlighting any scars or baseline asymmetry. The patient is then placed on a sterile, draped operating table and the areas requiring fat suctioning are infiltrated with dilute local anesthesia until turgid (tumescent technique; Table 254-2; see Chapter 253).

It takes at least 20 minutes for the epinephrine in the tumescent fluid to achieve hemostasis. The face is then anesthetized diffusely with dilute 0.5% lidocaine with epinephrine 1:200,000, and segmental nerve blocks are established where appropriate. For safety, the total lidocaine dose in the tumescent fluid should not exceed 35 mg/kg of body weight.

Fat Harvesting

Suctioning of the fat used for transplantation should be done by hand with an open-tipped harvesting cannula attached to a 10-mL syringe. After a hole is made with a 1.5-mm punch or No. 11 blade, the cannula is inserted into the deep fat and moved back and forth while the plunger on the syringe is retracted. Fat collection usually occurs quite rapidly and, due to the vasoconstrictive properties of the tumescent fluid, is nearly bloodless. After fat extraction, the syringes may be placed into a centrifuge and spun at 3,400 rpm for 20 seconds or left to stand for 20 minutes to allow separation of the hydrophilic tumescent fluid from the lipophilic fat. The infranate of tumescent fluid should then be decanted before the fatty layer is transferred to 1-mL syringes in preparation for injection into the face. Any supranate of ruptured fat cells (triglycerides and free fatty acids) should be discarded.

Fat Transfer

All AFT to the face is performed with the patient fully supine using an 18-gauge or smaller blunt cannula for infiltration. Incision sites can be made with an 18-gauge needle, a NoKor needle (Becton, Dickinson and Co., USA), or the tip of a No. 11 blade scalpel. Fat is infiltrated in a retrograde manner; that is, fat is injected only as the cannula is withdrawn. Injection is in small aliquots of 0.1 mL or less using a threading or depot method. Placement of fat always starts closest to bone when possible and then proceeds up through muscle and into subcutaneous fat. Fat is deposited in a crosshatched three-dimensional lattice and thus imparts structure as well as augmentation to the tissues. All areas of the face should be addressed to achieve filling laterally as well as anteriorly. The goal is to advance tissues forward and thereby elevate them away from the bone, fill in areas of shadow, and restore youthful contours.

Postprocedure Instructions

Immediately after the procedure and on and off for the next 2 days, ice should be applied to the face. The area suctioned is dressed with absorbent pads, and a snug garment is applied. Incision sites on the body and face are left unsutured. The patient is instructed not to submerge the body in water until all incisions are healed (approximately 1 week). Antibiotics must be continued for 6 days after the initial procedure. Intramuscular triamcinolone may be given to reduce postoperative edema.

Unique Complications

Postoperative edema and ecchymoses are common and last for approximately 2 weeks. Undercorrection with a gradual decrease in augmentation is common and usually represents a decline in edema rather than absorption of the fat. For this reason, fat transfer should never be recommended as a one-time procedure but rather as a series of treatments with cumulative augmentation and long-term results. Small, persistent lumps can occur that represent either fat cysts or accumulation of fat. They can be treated, usually to resolution, with intralesional injection of triamcinolone (2–4 mg/mL). If a larger fat lump is present, the best option is to feather it into the surrounding tissues with an infiltration cannula. Irregularities can also occur at the harvest site, but operator experience and judicious removal of fat makes this a highly unlikely event. Rarely, infections such as atypical mycobacteria can be seen and should be in the differential diagnosis for any nodules occurring up to 1 year following AFT.

Longevity

Many authors using a standardized, multilevel microinjection technique have published photodocumentation of long-term follow-up demonstrating persistence of autologous fat (Fig. 254-4).8 However, the controlled, double-blinded, multicenter studies available for evaluation of other fillers have not been done.

Patient Selection

Injectable silicone is categorically a permanent filler with a wide range of applications. It appears to provide permanent, cosmetically superior augmentation for treatment of HIV lipoatrophy, plantar defects, and scars. Historically, silicone injection has been associated with disfiguring tissue distortions and migration of product. These side effects can almost always be traced to the use of large-volume injections or non–medical grade silicone. Because of the controversial nature of silicone augmentation, patient selection for cosmetic indications is currently complex, and use of the procedure should be reserved for those physicians who have extensive experience in the injection of silicone as a filler and understand the concepts outlined in the Technique section.

Patients with a known history or autoimmune disease or with a history of a chronic or active infection should be excluded from treatment.

Formulation

Perhaps no other filler has both inspired such a loyal following and provoked such vehement opposition as injectable silicone. The most widely used available form of silicone oil is FDA approved for the treatment of retinal tamponade. It is not approved for the indication of soft-tissue augmentation. It is a sterile, impurity-free, medical-grade silicone oil at a 1,000-centistoke viscosity. It is noncarcinogenic and does not appear to be associated with arthritic disease in mice. After injection, silicone is encapsulated in collagenous fibrous tissue, so that final augmentation is a result of both volume of injected silicone and host tissue response.

Anesthesia

Currently available forms of silicone do not contain an anesthetic solution, because such small volumes are injected on each visit that ancillary anesthesia is not often required. If desired, a topical anesthetic agent containing 20% tetracaine or 4% lidocaine may be applied before the procedure.

Technique

Improper technique in the injection of silicone oil will almost guarantee permanent adverse sequelae. It is therefore absolutely necessary that a physician considering the use of silicone apprentice with an experienced practitioner. Silicone (1,000 centistoke) is highly viscous and must be injected through either a 26-gauge needle on a 1-mL syringe or a 30-gauge needle on a 0.3-mL syringe. Use of a microinjection technique is paramount to success with silicone, so large-bore needles are never to be used. The microdroplet injection technique involves injecting 0.01 mL of silicone oil, with the needle bevel down, into the deep dermis in a depot fashion at 1- to 3-mm intervals. Note that 100 droplets are therefore required to empty a 1-mL syringe. Except in the treatment of HIV cheek atrophy, it is rare to use more that 0.3 mL total per injection session. Treated areas are always undercorrected, and patients are instructed to return for multiple injection sessions at monthly intervals until full augmentation occurs.

Postprocedure Instructions

There is very little postoperative discomfort, edema, or ecchymosis after microinjection with liquid silicone. Ice may be applied if needed to lessen the risk of postinjection ecchymosis. Patients may apply makeup and pursue their daily activities as usual after injection.

Unique Complications

Most authorities on silicone use agree that the incidence of serious complications after the proper use of medical-grade silicone is very low. In an FDA-authorized study involving 1,400 patients over a 20-year period, 2 patients experienced serious side effects: one case involved migration of silicone after treatment with large volumes, and the second involved inflammation and necrosis in a patient with concomitant Weber-Christian disease and rheumatoid arthritis. Local granulomatous nodularities can occur many years after the cessation of treatment and are usually preceded by a systemic infection. Treatment regimens for granulomas include intralesional or systemic steroids, minocycline, and topical imiquimod.9

Longevity

The augmentation derived from liquid silicone injection is permanent. Many authors have published reports of long-term studies, some with 30-year follow-up, showing persistence of improvement. Patients receiving liquid silicone injections will continue to age, and, for this reason, additional augmentation may be required should neighboring areas of age-related atrophy develop.

Complications Associated with the Use of All Fillers

Vascular occlusion is perhaps the most devastating complication associated with the use of all fillers. This can manifest as local necrosis, central nervous system infarction, or blindness. Blindness and middle cerebral artery infarction have been described most often after fat transfer, but vascular occlusion with ensuing sequelae has occurred after the use of collagen and hyaluronic acid fillers as well. In theory, the central occlusive events have occurred from high-pressure injections with retrograde flow into arterioles that connect with the internal carotid system. It is therefore of utmost importance to keep the needle or cannula moving during withdrawal while depositing filler and to exert as little pressure as possible on the syringe. For similar reasons, when fat transfer is performed, only blunt cannulas should be used for infiltration.

Other complications common to the use of all fillers include ecchymosis, edema, extrusion or drifting of the filling substance, foreign-body reactions, changes in pigmentation, injection site scarring, overcorrection, undercorrection, misplacement, and infection.