Silicone gel breast implants have been used for elective cosmetic and reconstructive surgical procedures. As with any procedure, the physician and the patient must weigh the benefits and risks of any procedure prior to surgery. There has been a particularly significant amount of media, legal, and scientific focus on the risks of these silicone gel implants. Despite the long history of these implants, the risk assessment has to be based mostly on in vitro and animal testing, due to the limited clinical data available.
Current clinical concerns include fibrous capsule formation and subsequent capsular contraction as well as implant breakdown (gel bleed through the implant shell as well as shell rupture). Although there is sufficient evidence, at this time, to document the in vivo breakdown of these implants, the clinical significance is still uncertain due to the lack of conclusive clinical data. The moratorium on these implants, however, will probably prevent a complete determination of the clinical significance of implant breakdown.
Current designs, however, act as delivery devices for gel components because the shells do not provide an adequate barrier. Although silicone rubber is relatively inert, release of small particles (gel components and shell particles) can lead to ongoing inflammation and subsequent cytokine production. Also, ingress of lipids and fat soluble biochemical moieties alter the mechanical properties of the shell and may cause critical serum depletion of essential biochemicals. Although no causative link between silicone presence and immune problems has been established, silicones can act as an adjuvant and possibly worsen existing immune responses.
There is a subtle but significant difference in the way the scientific community determines risk from the manner of the legal community. A legal case has been made that silicone gel breast implants, particularly late 2nd generation implants, i.e., those implants made end-1970s and early-1980s, are unreasonably dangerous. The legal case for an “unreasonably dangerous” or defective device, is based on proving the device is not state of the art; its warnings are not adequate; the design is defective; there was inadequate testing; or the risks outweigh the benefits.
In the final analysis, from both a legal and medical perspective, the risk benefit ratio is critical. Ultimately this is a decision to be made by the patient and the physician, but it is particularly important that the risks for elective procedures be low. The absence of sufficient documented safety data led the FDA to state that the risks outweigh the benefits leading to the moratorium in 1990.
Questions regarding the lifetime of these implants and implications of particles on local and systemic responses need to be answered. There is a need to know how these particles form and determine the specific clinical significance of particle size, shape, chemistry, and density of these particles. Results from these studies should enable development of better screening tests for patients and of new devices with lower bleed rates, stronger shells, and longer lifetimes. More importantly, it will enable the patient and the physician to make better informed decisions.