Form-stable breast implants aren't a new development but they are rare ? in America, at least.

This product is an implant that offers a silicone ?shell? with a nearly solid gel texture on the inside, also made of silicone. This is a much firmer content than what is seen in American implants that contain saline fluid or a more diluted silicone gel. The form-stable implants, already legitimately used in Canada, Brazil and parts of Europe, haven't yet received approval from the U.S. Food and Drug Administration. As it stands, breast augmentation patients in the United States can only qualify for these special implants by qualifying for exclusive clinical trials and then agreeing take part in follow-up studies for up to ten years after the operation.

But those who are able to get involved might find that the form-stable breast implant suits them. To begin with, the product doesn't have the problem of rupturing and then leaking fluid ? typical with saline and other gel-filled units ? since the inside is too solid. Sources indicate that only one of these special implants ever cracked open; even then, the contents didn't leak anywhere. The texture of a form-stable implant also lends it to keeping its shape ? forever. And this implant happens to lack the saline version's ?fluid sac? softness that can lead to the odd rippling appearance on a woman's chest.

Perhaps the best news about the form-stable breast implant comes across in the name itself. A patient who receives these implants is sure to get the result of breasts that won't sag or become droopy over time. This is because the durable firmness of the thick silicone forces the breast to maintain the shape of the implant, rather than aging breast tissue dragging the implant downward. The intended form of the human breast seems to favor an invention such as the form-stable implant. Its strengths appear to provide a sturdy contrast to a bag filled with thin fluid liable to weaken and break.

The delay in American approval has been explained by the need for further testing. And the form-stable breast implant has indeed been criticized as having a few negative points. Its firmness means that it can't be deflated ? which means that a surgeon is required to make bigger incisions than he would for another kind of implant. It does reportedly cost many hundred dollars more than the other silicone versions. And for some women, its firm texture might lack a softness that feels natural to them. It is also true that because this implant doesn't change shape, it narrows a woman's options of breast appearance. To some, the form-stable operation produces cleavage that lacks flexibility and has a predictable look.

Regardless of which implant they choose, Americans have chosen enough of them to make breast augmentation the most common surgical cosmetic procedure in this country. The American Society for Aesthetic Plastic Surgery recently proved it by citing more than 355,000 breast operations in 2008.