The standard implant in the United States has been saline filled, ever since the FDA moratorium on silicone gel filled breast implants in 1992. The type of implants that were available before the ban are available today as part of an “adjunct study,” which is open to patients with congenital deformities or having a revision for particular reasons.
What distinguishes cohesive implants is that the silicone gel is firmer, essentially a soft solid. If a cohesive implant is cut in half, there is no gross movement of gel, and the implant maintains its shape.
The way these are made is that the company uses more “crosslinker” in the making of the implant. The ingredients are the same, but with more crosslinker added, it makes the gel firmer.
The term “cohesive” has been bastardized in recent years. Cohesive breast implants implies form stability, or form retention. That means that in any position, the implant maintains its shape. That is an important distinction, because it means that the shell should not fold, and that it will maintain a particular shape.
Unfortunately, given the recent media attention to cohesive implants, many are using the term to describe “regular” silicone gel implants. Technically, they are correct; all silicone gel is cohesive to some degree. But the term cohesive has always meant form stability, and when patients ask for cohesive gel, it is because they are looking for an implant with those particular characteristics of durability and shape retention. Hopefully, the terminology will be clarified in the coming years.
A breast projects more at the bottom than at the top. Therefore, it makes sense for an implant to be shaped that way. And the thinner an implant is at the top, the more gradually and naturally it will feather into the upper chest, making itself less conspicuous. Without a cohesive, form stable filler, there is little point in making shape into an implant, as the implant will ultimately lose the shape. But with a form stable filler, the shape will be maintained.
Form stable round cohesive gel implants are available in Europe, but not in the United States. There is actually very little use for them. If you look at an implant lying on its side on a table, it looks much like an M&M. But when it is held upright, the upper pole gradually collapses. It is that upper collapse that allows those implants to look natural (though it is doing so at the risk of folds on the implant shell.) A true cohesive round does not do that. By maintaining that M&M shape when vertical, it creates a dome-like, relatively top-protruding shape.
However, cohesivity is not a black and white issue; there is an endless continuum in cohesive gel from very liquidy to very solid. On Silimed’s cohesive clinical trial, there are 4 different round gel options. These are more cohesive than implants made in the past, and can be considered cohesive, but they are not as cohesive as their anatomically shaped cohesive gel implants or the anatomic cohesive implants by Mentor or Allergan. They fold less than gel implants of the past, but they are not quite form stable, in terms of their ability to resist folds or predictably maintain a shape.
All anatomic (a.k.a. teardrop) shaped implants are textured, as the texturing increases friction and helps keep them from rotating. Since a teardrop implant is different at the bottom than the top, it is important that it maintains its position.
The Silimed round implants come in both smooth and textured surface, but remember that while relatively more cohesive than most other silicone gel implants, they are not form stable like their anatomically shaped cousins.
The Sientra breast implants (formerly known as Silimed during the clinical trials) was FDA approved in March of 2012 and is available for use by all US plastic surgeons. Interestingly, Sientra will only sell its breast implants to real plastic surgeons – those certified by The American Board of Plastic Surgery. The other manufacturers will sell their implants to any doctor, whether or not they are actually plastic surgeons. At the time of this writing, both the Mentor highly cohesive implant – known as the CPG and as MemoryShape, and the Allergan highly cohesive implant – the Natrelle 410, are still only available to a very limited group of physicians and patients participating in clinical trials.
With the approval of the cohesive breasrt implants made by Sientra, gummy bear implants area available for all women seeking either first time augmentation, revision augmentation, or reconstruction after mastectomy. The only limitation is that the FDA only approved the implants for primary augmentation in women 22 years of age or older.
This is a loaded question and the answer depends upon whom you ask. All implants available, whether round or anatomically shaped, are cohesive. In the old days, implant fillers were much more of a liquid, and all silicone gel implants today are filled with relatively gelatinous silicone. However, when we use the term “cohesive,” what matters is that the implant maintains a particular shape and that the gel doesn’t migrate within the shell. Unless the gel stays in one part of the shell, there is no way to control the shape of the breast. So it is important that round implants do not have the most cohesive gel in them, because if they did they would look too round. It is the redistribution of the slightly softer gel within round implants that allows them to look like a breast. In Europe there are round implants filled with highly cohesive gel, but those implants look very round and fake and there are no plans to bring them into the United States. Sientra makes a round implant, and though some surgeons will call the implant highly cohesive, in fact it behaves no different in patients than the standard round silicone implants made by the other manufacturers.
Many patients and even some plastic surgeons have the mistaken believe that highly cohesive implants cannot break. Unfortunately they can break. The rate of breakage is lower than with other implants, but it can happen. The number of cases is too low to draw conclusions about what happens. But in anecdotal discussions between plastic surgeons, the gel stays within the scar tissue that is around the implant. Some people have thought that the gel is so thick that it doesn’t even leave the shell, but that is clearly not true.
The numbers of patients with ruptured gummy bear implants seems to be low. In some cases there can be a change in the shape or feel of the breast and breast implant. In one case a patient developed a large soft bump in the upper outer breast, with a bit of a depression beneath it. The breast can feel soft, look distorted, or somehow change its appearance. Presumably there are cases in which the implant has broken but it is not perceptible to the patient or doctor. In these cases an MRI is the only way to diagnose the problem. In fact, patients receiving any type of silicone breast implants, including highly cohesive implants, are advised to get an MRI every other year to check for “silent rupture.” While patients are all made aware of this, in reality very few actually get these MRIs.
There is no science or standardization to any of those terms. They are invented by surgeons, manufacturers, and patients to sound interesting and appealing. The manufacturers want everyone to think their products are different, doctors try to get an edge on one another by acting like they are doing something special, and patients come up with colloquial terms to use when discussing one another. When cohesive implant trials began in 2001, everyone knew what cohesive meant: it meant that the implant was filled with gel of sufficient cohesivity to allow that implant to maintain its shape. Gummy bear is a term that nicely describes that special combination of softness and shape retention, but many surgeons applied that term to implants that were not form stable. But here is a run down on those terms:
Gummy Bear is a colloquial term invented by an implant company president to describe the characteristics of (at that time) the Inamed Style 410 (later the Allergan 410.) He was biting the heads off of gummy bears during a meeting and thought this would be a good term.
Cohesive was the term that was originally used to describe the filler in implants that would maintain their shape. As patients asked for these and while the FDA still had not given clearance for these, many plastic surgeons and one implant manufacturer started saying that “all implants are cohesive.” That was sort of true, but it ruined a term that everyone was familiar with.
Once the term cohesive was bastardized (see above,) plastic surgeons experienced with these implants started using the term highly cohesive to distinguish these implants from standard implants. In particular, it refers to an implant filler that is thick enough to allow the implant to maintain a shape.
Form Stable means a breast implant will maintain a particular shape. The shape of a standard silicone (or saline) implant changes dramatically from gravity and pressure. But form stable implants, such as the Allergan 410 and the Mentor MemoryShape (aka the CPG), hold their shape to a much greater extent and are generally considered form stable. But realize that there is really no such thing as a Form Stable Implant.
MemoryGel™ is the trademarked term for the standard silicone gel used in Mentor breast implants. But it has no memory whatsoever; if you put an implant filled with memorygel™ in your hand it will change in shape as you move your hand. This is just a fancy term for standard silicone implants. The gel is certainly excellent, but the name suggests a quality that it does not possess.
MemoryShape™ is the name Mentor has given to its most cohesive breast implants. These have always been know as CPG (Contour Profile Gel), but they have now used this term to refer to these implants that maintain their shape. Of course, no implant truly maintains its shape, but these implants are all teardrop and are Mentor’s most highly cohesive or gummy bear implant.
SoftTouch™ is a silicone filler made by Allergan but it is not available in the United States. Its cohesivity is in the middle between their standard silicone gel and the gel that is in the 410. They can use this in round implants or even in the 410. Round implants fileld with SoftTouch™ gel are called the “Inspira.” 410 implants filed with this are called the “410 SoftTouch.”
Each manufacturer uses its own standards and they do not share them. So it is impossible to compare. It is complicated by the fact that the filler alone is not the only determinate of the form stability of an implant. So too is the amount of fill of the implant shell (a shell of any given size will seem more cohesive if it is filled more and less cohesive if it is filled less,) the thickness and shape of the shell, and the degree to which the gel sticks to the inside of the shell.
Some of the doctors on this site have followed many hundreds of patients for over ten years, but all have done so for at least five. All have either lectured, written, or taught about these implants.
Technically it is correct that all implants are cohesive. But the original use of the term referred to implants that were able to hold a shape. Today plastic surgeons may refer to those implants as highly cohesive.
There was a teardrop implant that was popular in the 1980s. At first it looked good, but then the shape was lost and they frequently broke. It turned out that while the implant initially felt cohesive and looked nice, things soon changed. The shell got thinner and weaker, and the liquidy gel fell to the bottom. Shape was lost and the implant broke. The whole point of a cohesive filler was to use the filler itself to maintain the shape without relying upon the shell.
The first highly cohesive implant of the modern era was the McGhan 410, invented in the late 1980s by John Tebbetts of Dallas. In 1992, the FDA placed a moratorium on the sale of silicone breast implants, which prevented that implant from being sold here. They made changes to the design of the 410 shell so that it could be filled with saline, and that was called the McGhan Style 468. Meanwhile, the implant was available throughout most of the civilized world. US clinical trials of the implant began in 2001, and it was expected that they would be FDA approved within three or four years.
When the filler is highly cohesive, it maintains its distribution within the shell. When that happens, shape is relatively maintained, allowing the surgeon to use the implant shape to remodel the breast. There should be less folding, less of a chance of leakage, perhaps less migration of gel after a leak, possibly greater longevity, and peace of mind for some patients.
A necessary part of holding a shape is that they will feel a little firmer. While hard would be a bad thing, firm is okay. Most patients don’t consider them to be firm, but some do. Part of that is personal perception of what feels right in a breast. Some patients own breasts are naturally firmer than these implants, and they never consider them to be firm. In contrast, some patients with softer, fattier, and slightly droopy breasts may be more likely to think these implants are firm since they feel firmer than their own breast tissue.
Since cohesive implants have a less malleable shape, they need to be fit much more precisely to the dimensions of the breast than regular gel (or silicone) implants which are capable of conforming to a wide range of spaces. Using shaped implants requires more technical precision than using standard implants.
This was the very first of the highly cohesive implants. It has been a widely used implant worldwide since the early 1990s. It comes in 12 different shapes for any given volume, giving the surgeon a wide range of shapes to choose from to create the ideal shape for a patient’s breasts. It is probably the firmest of the implants, though the additional firmness is not very distinguishable once in the body from other cohesive implants. In Europe there is a version of it called the 410 Soft Touch, which is a softer version of it. But the trade-off with that is that it has less of an ability to maintain its shape. The 410 has been in clinical trials in the United States since 2001. The company that launched the implant was called McGhan, which was later bought by Inamed, which was then bought by Allergan. So each of those names has been associated with the 410. Dr. Teitelbaum used hundreds of 410 implants during its clinical trial in the United States, as a lead researcher. He also was videotaped using the implants, which is part of Allergan’s physician teaching course on the proper use of the 410. Dr. Teitelbaum was also a primary writer of Allergan’s 410 educational curriculum. Photos of his own 410 patients are prominently displayed in Allergan’s 410 marketing materials, so he is undoubtedly a well-recognized expert using these implants.
CPG stands for Contour Profile Gel. It is Mentor’s most cohesive anatomically shaped implant. It was designed after the 410. It seems to be slightly less cohesive. The CPG has similar shapes to the 410, but the dimensions are notably different. It is probably a matter of surgeon and patient preference as to which shape is best. Mentor makes three types of silicone: Cohesive I, Cohesive II, and Cohesive III, with I being the least cohesive and III being the most. The standard silicone implant in the USA is a Cohesive I. The CPG is a cohesive III. There are no Cohesive II implants available in the United States. Mentor refers to the silicone in Cohesive I and Cohesive II implants as “memorygel”, and refers to the silicone in the CPG as “memoryshape.” Dr. Teitelbaum has experience using the CPG on hundreds of patients as a participant in their pivotal United States clinical trial.
MemoryGel is Mentor’s trademarked name for the silicone gel in its standard implants. MemoryShape is the trademarked name for the silicone in the CPG highly cohesive anatomic implant. The term MemoryGel is somewhat misleading because the implant does not behave with any memory: its shape is malleable and affected to gravity, not returning to any particular shape.
Sientra is the US distributor for Silimed implants, which are made in Brazil. After 22 years of only two US implant makers (Allergan and Mentor,) Sientra became the first new manufacturer approved by the FDA in March 2012. They make both round and anatomically shaped implants. Dr. Teitelbaum has used them for many years on their clinical trial in the United States. Their round implants feel softer than their anatomic implants, though they are technically the same implant.
There are innumerable subjective distinctions Dr. Teitelbaum can make about these implants after using hundreds of them. They each have specific shapes and degrees of cohesivity that work in different situations. The problem is that the manufacturers will not release even to surgeons the critical parameters that enable a meaningful, scientific distinction between them. So we are left with nothing but surgeon impressions.
When the FDA approves an implant, the manufacturer is given a range of gel cohesivity for that approval. No one knows exactly how Sientra has done it, but the presumption is that the round implants are on the soft end and the shaped implants are on the firm end of the spectrum of their approval.
Even the most cohesive implants such as the 410 can ripple, but does so less often and to a lesser extent than standard silicone implants. But the most critical thing in rippling is not the implant; it is the thickness of the tissue over the implant and whether the breast envelope is filled by the implant.
Contrary to popular belief, cohesive implants can break. They appear to do so less often than regular silicone implants, but they are not unbreakable.
If the shell is disrupted, cohesive implants can leak. Their gel is much thicker than that of standard implants, so the gel tends to stay around the implants. But it is a misnomer that these implants cannot leak.
Cohesive implants can be a part of the solution to correct rippling. In some situations they do correct rippling. But rippling is mostly about the thickness of the coverage and whether the breast envelope is filled. Many patients and even plastic surgeons view cohesive implants as a panacea for rippling, and though they can be great, they are not a panacea.
Teardrop implants can rotate. But if the implant fits the tissue, and if the surgeon makes a pocket that fits the implant, then rotation should be a very infrequent problem. But it always remains a risk with anatomically shaped implants. It is a reason why shaped implants aren’t always a good choice for revisions. It is the pressure of fresh tissue on the implant that helps maintain its position, and in revisions that is often not the case.