The ASDS Emerging Technology Report is a new member service designed to inform dermatologic surgeons of the latest technologies or procedures entering the marketplace. The series represents a distillation of available published scientific data and anecdotal information on a specific technology or procedure and should not be misconstrued as an endorsement by the ASDS. The Society encourages its members to use their independent judgment in applying any new technology or procedure in the care and treatment of their patients.
Silicone is a generic term that refers to polymers of dimethylsiloxane composed of elemental silicon, oxygen and methane subgroups. Silicone can be a solid or a liquid, with the viscosity of liquid silicone expressed in centistokes and being related to the polymer length. Silicone is thermally stable and chemically and biologically inert. As an injectable filler, it is considered permanent and is not degraded by the body.
Silicone polymers have been manufactured as fluids, rubbers, resins, gels, adhesives and foams. Medical grade liquid silicone is employed as a coating for needles, catheters and as a component of certain cosmetics and over the counter anti-flatulants. Although never specifically FDA approved for soft tissue augmentation, injection of liquid silicone was reported for such use in the 1960s. A variety of silicones of varying purity were frequently employed during the ensuing decades. Often, impure industrial grade silicone was injected in a large bolus. A variety of adverse events have been reported, including cases of migration and granuloma formation. The FDA banned liquid injectable silicone in 1992 because of the unknown nature of the product and the possible risks of inflammatory skin reactions. All forms of implantable silicones were banned by the FDA in 1992, citing concerns over the possible relationship between silicone breast implants and systemic disease. Further study has revealed no relationship between implantable silicone and systemic disease. In 1994 and 1997 respectively, two highly purified silicone oils, Adatosil 5000 and Silikon 1000, were FDA approved for treatment of retinal detachment by way of intraocular injection tamponade. In 1997, the FDA Modernization Act allowed for off label use of devices such as liquid silicone, a provision previously applicable only to drugs. Currently, Silikon-1000, due to its high purity and lower viscosity allowing injection through a 27 G needle, is the most appropriate substance for soft tissue augmentation. Although now legal in the U.S., its use for this indication is strictly off-label. Liability carriers have varied regulations regarding use of liquid injectable silicone. Various forms of highly purified injectable liquid silicone have been studied for soft tissue augmentation, and FDA studies are currently underway to further assess safety and efficacy.
Currently, liquid injectable silicone remains controversial. Critics state that liquid injectable silicone is inherently unpredictable, with adverse events such as migration or granuloma formation appearing frequently months to years after injection, despite use of appropriate substance and technique. Advocates rely on a wealth of anecdotal and long-term data to assert that liquid injectable silicone is routinely safe and effective and is often capable of giving superior aesthetic results as long as the following rules are followed: 1) Use highly purified silicone intended and FDA approved only for injection into the human body (Silikon-1000). 2) Adhere to strict microdroplet technique defined as injection of 0.01 cc injected into the subdermal plane at 2-4 mm intervals; 3) Inject very small volumes (0.5 cc or less for smaller defects, and up to 2 ccs for severe facial lipoatrophy); 4) Limit injection sessions to once monthly or longer. Fibroplasia develops around the microdroplets limiting migration and contributing to further augmentation.
Liquid injectable silicone may be employed for a variety of cutaneous atrophies that are amenable to injectable soft tissue augmentation, including acne scars and HIV associated facial lipoatrophy.
Liquid silicone should not be injected into active sites of infection. It should also not be injected into breasts or genitalia. It is contraindicated for correction of “bound down” or “ice-pick” acne scarring. Lumps are frequently reported with superficial intradermal injection. Intradermal injection should be avoided, except in very small amounts for the treatment of dermal atrophic scarring.
Granuloma formation manifesting as firm to rock hard inflamed nodules, lymphatic obstruction manifesting as peau de orange texture, migration, cutaneous necrosis and pigmentary abnormalities over the injection site have all been reported. Adverse events may appear months to years after injection. Evidence suggests that strictly adhering to the aforementioned rules greatly limits the occurrence of adverse events. Granulomatous reactions have been reported when an active infection such as a dental abscess appears elsewhere. Granulomatous reactions have been successfully treated with intralesional steroids, antibiotics, etanercept, and topical tacrolimus.
Injected correctly, liquid injectable silicone may meet many of the requirements for an ideal filler. It will continue to be controversial until further well designed, long term studies resolve questions of safety and long term efficacy. Appropriate injection techniques require a learning curve, and physicians should seek appropriate training before employing this substance. Furthermore, physicians should be aware of limitations of their specific liability carrier regarding liquid injectable silicone.
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Seth Matarasso, MD, Chair
Kenneth Arndt, MD
Kimberly Butterwick, MD
Mary Christian, MD
Mitchel Goldman, MD
Douglas Hamilton, MD
Derek Jones, MD
Rhoda Narins, MD