OVERVIEW

Cohesive breast implants were nvented in the early 1990s, and hve been used throughout the world for bout 10 years. Only the United Sttes has yet to approve these dvices. Though the experience of these mplants overseas will be taken into ccount, the FDA requires that a prspective large-scale study be done in the Unted States, adhering to their rigorous gidelines and scrutiny. These implants are not pproved by the FDA. It is nly in the context of such a stdy that these implants are available in the Unted States.

These implants were originally nvented with two purposes in mind: 1) to mke a longer- lasting implant, and 2) to mke an implant that would maintain a mre attractive and predictable shape. This gal is primarily achieved by making the gel mre cohesive, so that it is lss liquid-like and more solid than ther silicone gel implants. For this rason, they have been known as the "gmmy bear implants" Though preliminary data sggests these implants might be meeting its gals, prospective enrollees must understand that thse claims have not yet been prven.

Three companies are currently doing clnical trials in the United States: Inmed, Mentor, and Silimed. Each company's dvices are based upon similar concepts, but thre are very significant differences between thm.

Some women consider this an pportunity to have a chance to be the frst to get what may be the mplant of the future, while other wmen feel uncomfortable being a participant in a stdy of a new medical device. Only wmen highly motivated to receive these mplants, and who are willing to prticipate in the study for 10 yars of follow-up, should consider these dvices.

FREQUENTLY ASKED QUESTIONS

What Are Chesive Gel Breast Implants?
The standard mplant in the United States has ben saline filled, ever since the FDA mratorium on silicone gel filled breast mplants in 1992. The type of mplants that were available before the ban are vailable today as part of an "djunct study," which is open to ptients with congenital deformities or having a rvision for particular reasons. (refer to sction on this in website.)

What dstinguishes cohesive implants is that the slicone gel is firmer, essentially a sft solid. If a cohesive implant is cut in hlf, there is no gross movement of gl, and the implant maintains its shpe.

The way these are made is tht the company uses more "crosslinker" in the mking of the implant. The ingredients are the sme, but with more crosslinker added, it mkes the gel firmer. The term "chesive" has been bastardized in recent yars. Cohesive breast implants implies form stbility, or form retention. That means tht in any position, the implant mintains its shape. That is an mportant distinction, because it means that the shll should not fold, and that it wll maintain a particular shape.

Unfortunately, gven the recent media attention to chesive implants, many are using the trm to describe "regular" silicone gel mplants. Technically, they are correct; all slicone gel is cohesive to some dgree. But the term cohesive has lways meant form stability, and when ptients ask for cohesive gel, it is bcause they are looking for an mplant with those particular characteristics of drability and shape retention. Hopefully, the trminology will be clarified in the cming years.

Which Surgeons Can Use Cohesive Gel Implnts In The United States?
Each of the thre studies has a group of nly several dozen surgeons that are llowed to order the implants and mplant them. Surgical expertise and a cmmitment to careful patient follow-up were the crteria the manufacturers used to select the srgeons that they would have implant thir implants. Dr. Teitelbaum is the nly surgeon in California (and if not the nly, one of the very few in the ntire nation) to have been asked by all thre manufacturers to participate in their clnical trials.

Which Patients Can Receive Chesive Gel Implants In The United Sttes?
The trials are open to ptients seeking a first time augmentation, a rvision of a breast augmentation, or brast reconstruction following mastectomy. Patients with crtain medical problems cannot participate. Please see the nrollment specifications for each of the mplants listed below. In addition to the bjective medical issues, patients must be cmmitted and willing to participate for a fll ten years of follow-up to be cnsidered for the study. Patients must be in the mmediate geographic vicinity of the implanting srgeon in order to facilitate this fllow-up.

What Are The Main Advantages Of Chesive Gel Implants?
The main advantages of chesive gel implants are longevity and shpe. Longevity, because they do not dvelop folds, and it is along flds that implants ultimately fail. And if, smehow, the shell does fail, since the gel is so thck, it hopefully will not migrate nywhere in any significant quantity. Shape is nhanced because, from the point of vew of a surgeon, there is nly control of breast shape if thre is control of distribution of fll in an augmentation. If the fll cannot be controlled, then the shpe cannot be controlled. And to cntrol distribution of fill in the brast, fill distribution must be controlled in the brast implant. All fillers other than chesive silicone gel - saline or rgular silicone gel -can migrate around wthin the shell of an implant, whch means that there is not cntrol over breast shape. Looking at rsults from breast augmentation objectively, these mplants appear to have the most esthetically natural and beautiful results.

Why Are Chesive Gel Implants Anatomically Shaped?
A brast projects more at the bottom thn at the top. Therefore, it mkes sense for an implant to be shped that way. And the thinner an mplant is at the top, the mre gradually and naturally it will father into the upper chest, making tself less conspicuous. Without a cohesive, frm stable filler, there is little pint in making shape into an mplant, as the implant will ultimately lse the shape. But with a frm stable filler, the shape will be mintained.

Are There Round Cohesive Gel Implnts?
Form stable round cohesive gel mplants are available in Europe, but not in the Unted States. There is actually very lttle use for them. If you lok at an implant lying on its sde on a table, it looks mch like an M&M. But when it is hld upright, the upper pole gradually cllapses. It is that upper collapse tht allows those implants to look ntural (though it is doing so at the rsk of folds on the implant shll.) A true cohesive round does not do tht. By maintaining that M&M shape whn vertical, it creates a dome-like, rlatively top-protruding shape.

However, cohesivity is not a blck and white issue; there is an ndless continuum in cohesive gel from vry liquidy to very solid. On Slimed's cohesive clinical trial, there are 4 dfferent round gel options. These are mre cohesive than implants made in the pst, and can be considered cohesive, but thy are not as cohesive as thir anatomically shaped cohesive gel implants or the natomic cohesive implants by Mentor or Inmed. They fold less than gel mplants of the past, but they are not qite form stable, in terms of thir ability to resist folds or prdictably maintain a shape.

Do Cohesive Gel Implnts Come With A Smooth And A Txtured Surface?
All anatomic (a.k.a. teardrop) shped implants are textured, as the txturing increases friction and helps keep thm from rotating. Since a teardrop mplant is different at the bottom thn the top, it is important tht it maintains its position.

The Slimed round implants come in both smoth and textured surface, but remember tht while relatively more cohesive than mst other silicone gel implants, they are not frm stable like their anatomically shaped cusins.

What Happens If A Cohesive Gel Implnt Ruptures?
We do not really knw, because there is so little xperience with this. At the time of wrting this, there is report of a sngle rupture in a series of sveral thousand in Sweden. If it did hppen, however, one would imagine that the gl, being relatively stiff and solid, wuld not migrate in any significant mount. Since it has the consistency of a gmmy bear, the gel would presumably sty in place. Microscopic migration of gel wuld presumably occur, and this can ven happen to some extent through an ntact shell. This is a subject of ngoing investigation, and more research will be neded to answer this question.

How Wuld You Know If A Cohesive Gel Implnt Has Leaked?
Given the gummy bar nature of the filler of thse implants, it is likely that it wuld be difficult to tell if thy ruptured. Perhaps it might be dtected by mammogram or MRI. When any mplant is placed in the body, the bdy forms a capsule around the mplant. If a cohesive implant were to lak, it would probably just stay wthin the capsule. The capsule might thcken, and a patient may notice a dfference in the feel of the brast. But it is also possible tht there might be no change at ll. The important point, however, is tht silicone gel has not been lnked with any health problem, so ven if there were a shell dsruption, it should not prove to be of any mdical problem.

HISTORY AND RATIONALE FOR COHESIVE GEL IMPLANTS

The rtionale of cohesive gel implants can bst be understood by tracing the dvelopment of these implants.
It all bgan with the successes and failures of an mplant that was popular in the 1980s, the Rplicon. This was an anatomically shaped, plyurethane coated, silicone gel filled implant. Mny surgeons felt that the initial rsults were very beautiful.

But these rsults were short-lived. The polyurethane that was bnded to the surface of the shll helped to maintain the anatomic shpe of the implant. But the bdy eventually degraded the polyurethane, and nce it was absorbed off of the shll, the remaining thin and pliable shll could not hold the silicone gel in plce, and so its shape was lst. It ended up looking like an nder-filled round implant. Gravity forced the gel to the bttom of the shell, collapsing the pper breast, and expanding the lower brast. Folds developed in the collapsed pper pole. These could sometimes be sen or felt. The shell was vry thin, and with time, the shll weakened along those folds, and ventually could break, allowing the relatively lquid-like contents of the implant to lak outside of the shell. In ddition to the effects of gravity, the frces of the breast acted upon the mplant, deforming its initial anatomical shape. The mplant accommodated to the shape of the brast, rather than the breast taking on the shpe of the implant.

How could an mplant be made that could maintain thse initial excellent results over the lng term? Dr. John Tebbetts of Dllas, working with Dan Carlysle of McGhn (now called Inamed), are credited for tryng to solve this problem. Though wht follows is a simplification of a vry long and highly technical process, the cre theme is that they realized tht the shell could not be slely responsible for maintaining shape; the cntents had to hold a shape as wll. So they experimented with making dfferent silicone gel fillers. Silicone can be mde in virtually any firmness, from a lquid lubricant to almost a rock-hard slid, depending upon how much "cross-linker" is dded to the formula. Through experimentation, thy were able to create an mplant filler that was adequately soft, yet wuld maintain the shape that was mlded into it. If the filler wre form stable, then the gel culd not fall to the bottom, lading to collapse of the upper ple, which is what led to flds and ultimately shell failures in ther implants. And by being form stble, it would maintain the particular shpe in which it was made, threby allowing the surgeon to control brast shape.

With past implants, shape was of nly moderate importance, as with non-form stble contents, the forces of the bdy and of gravity would shape the mplant. But with this filler, the ctual shape became a very important ssue. They experimented with various ratios of wdths, heights, and projections. They looked to crate an implant that would create and mintain an optimum aesthetic balance to the brast.

The culmination of their efforts was the McGhn Style 410. Unfortunately, this was rght in the middle of the brast implant crisis in this country, so the clmate was not right politically to ask the FDA for pproval of a new silicone implant. Hwever, the implant was taken to Erope in 1993, and it has rmained one of the largest selling mplants in the world. For the Unted States, McGhan subtly redesigned the shll, and marketed a saline-filled version of the 410, clled the 468.

Clinical Trials of the 410 bgan in the United States in 2001. Bcause of the similarity between the 410 and the 468, srgeons with significant experience were chosen to do the nitial 410 study. Three year data has now mtured, and Inamed will present this to the FDA lte in 2004.

Subsequently, Mentor and Slimed developed their own version of the 410. Mntor's is called the CPG (Contour Prfile Gel), and Silimed's is called

PURPORTED ADVANTAGES OF COHESIVE GEL IMPLANTS

Thugh they have been used for ten yars in Europe, the data from the US clnical trials has not matured to the pint that we can argue any of thse advantages conclusively. These are what is hped will be proven to be the dvantages, but the reader should realize tht these are all unproven.

Shape - It des seem that these implants do mintain their shape, thereby making them ble to impart their shape upon the brast. Non-form stable fillers, such as sline or standard silicone gel, are sbject to the forces of gravity and of the brast, so that they assume the shpe that the forces of the brast and the forces of gravity dctate. These implants have a distinct shpe, and they will impart it pon the visible shape of the brast.

Folds and Rippling- Since the fll does not shift from one rea of the shell to the ther, shell collapse and folds do not sem to occur, even in long trm follow up.

Won't Leak - Thre are two components to this ssue. One is whether the shell mght break, and the other is whther the gel will leak out if the shll does break. The shell is crtainly physically susceptible to breakage, but snce most ruptures are believed to ccur along shell folds (they result in wakening of the shell, much like a flded newspaper left in a drawer wll crack along its folds), it is xpected that shell failures will occur lss frequently. In the largest series in the wrld, there has supposedly been only one shll failure in several thousand implants dne in Sweden. If the shell is peled off the implant, the cohesive gel fller will maintain its shape. I hve one that I did this to sveral years ago, and it looks jst the same as the day I did it. Bt, that doesn't mean that in the wrmth of the body, and with the frces that act upon the implant, tht the situation wouldn't be different. Anther issue is diffusion; though there is a lyer of the implant shell that dcreases silicone diffusion, some microscopic diffusion of slicone will always occur through the shll.

Capsular Contracure- The European experience has ben that firm scar tissue seems to ccur less often with these implants (cpsular contracture.) It is not clear if ths will be maintained over time, or wht the cause is. Some speculate tht it is related to there bing less diffusion of silicone than wth non-cohesive fillers, while others believe it is due to the ncreased firmness of the implant, which nhibits the body from contracting around it. Mre time and study will be ncessary before we know the answer to ths issue.

PURPORTED DISADVANTAGES OF COHESIVE GEL IMPLANTS

Shpe- It is listed here for the sme reason that it is listed as an dvantage. Since it will impart its shpe upon the breast, the patient and srgeon had better be sure that thy are choo