Truth on ‘Cohesive’ Gel Implant

Pierre Blais J. J. B. Blais, B. Sc., Ph.D., C. Chem., F.C.I.C. was the former Senior Scientific Advisor for Canada’s now-defunct Department of Health and Welfare for fourteen years. He now runs Innoval Consultants, a firm engaged in the design, testing, and failure analysis of high risk medical systems. In his line of work he has examined over 7,000 cases of explantation, from which they have recovered over 9,000 different implants. Blais says they’ve seen “every single type that has ever been used worldwide. Some are as old as the 1950’s.”

The terms “cohesive gel” and “gummy bear” were introduced in breast implant promotion circa 2005 and have now become ubiquitous. Citing testimonials from conspicuous plastic surgeons, internet websites describe the “cohesive-gel” breast implant as a recent innovation of great merit. Such implants are presented as longer-lasting, providing a more attractive shape, safer, and having undergone rigorous testing.

“Cohesive gel” is an old term but in the context of breast implants it is an oxymoron. The technology employed to fabricate gel-filled breast implants requires that the gel be transformed from an invasive liquid to a stable semi-solid. This is achieved by mixing reactive liquid chemicals in various proportions and “baking” the mixture until it congeals into a mass. The technology to achieve cohesivity is described in patents of the late fifties and early sixties and remains essentially unchanged. Cohesive-gel implants commercialized nearly half a century ago fell into disuse because plastic surgeons did not like their inability to deform during surgery, preferring pliable implants that could be stretched and “stuffed” through a small incision. The early cohesive-gel implants were abandoned in favour of soft, stretchy, thin-shelled products that dominated the market until 1992 when the U.S. Food and Drug Administration (FDA) imposed a Moratorium to restrict use of silicone-gel-filled implants. Thus, to present the “cohesive-gel” breast implants as an innovation of recent origin is incorrect.

Claims that the currently promoted “cohesive-gel” implants are longer-lasting and safer are not demonstrated. Implant durability is unrelated to cohesivity of the filling gel. Instead, durability is determined by how the user’s tissue reacts to the foreign object and its effluents. The tenacity, chemical resistance, and ability o f the shell to resist stresses created by user movement are the key factors that determine how long an implant shell can hold its filling gel. Implants of any type, cohesive gel or not, drastically change the environment where they are implanted. Viable tissue is converted to hard frangible material intermingled with calcific deposits, a necrotic process which ultimately causes the implant to be surrounded by dead and abrasive material which erodes the shell. Compression by the surrounding tissue capsule deforms the implant and causes the shell to crease, leading to fracture. Calcific deposits create an alkaline environment which chemically attack the silicone shell causing it to fragment to inflammatory debris. The same environment converts the gel to an invasive liquid. These processes accelerate as the implant ages. Therefore, there is no basis to claim that a “cohesive-gel” implant is longer-lasting or safer.

More than 700 types of implants of assorted shapes and sizes have been commercialized since the sixties. All have been marketed on the belief that the breast would imitate the shape of the implant. Experience reveals otherwise. Within several months following implantation, contractile tissue forms around the implant. This process, combined with the anatomic constraints imposed by the user’s chest, deform the implant to an irregular spherical shape, creating the classic augmented breast profile. Nothing short of a hard, nearly rigid implant could retain its original shape after several years of sustained contracture. The claim that the “cohesive- gel” implant imparts a more attractive breast shape is at best wishful thinking.

Pre-clinical and clinical testing of breast implants has never been a serious undertaking. The architects of the FDA’s 1992 Moratorium attempted to change this long-established practice. Breast implant manufacturers were compelled to conduct controlled studies on breast implant safety, upgrade quality assurance practices, and maintain patient follow-up. In response, the three surviving breast-implant manufacturers agreed to the set conditions hoping that the FDA would approve the open sale of their products. Findings from the studies were at best mediocre. Nevertheless, and largely because of pressure from special interest groups, the FDA conceded to the manufacturers’ demand in 2006 and silicone-gel-filled breast implants were declared “approvable” for breast augmentation.
The FDA’s approval had little to do with “rigorous testing”. By 2010, flaws had become obvious in the promoters’ sponsored studies. Adverse events culminating in implant removal and individuals lost to follow-up were the most noteworthy findings, the same observations which characterized earlier testing of breast implants. Retrospectively, the tests were neither rigorous nor specifically applicable to the currently-promoted “cohesive-gel” implants and claims of superior performance and safety remain debatable.

Through repetitive promotion, the belief has spread that breast implants marketed post-FDA Moratorium are “new and improved”. This belief is illusory. Currently promoted breast implants are basically the same products which were widely sold during the early seventies. They embody minimal design changes and employ substantially identical ingredients. Manufacturing processes are similar albeit more mechanized, reflecting a desire to reduce production costs.

In summary, the events of the last four decades give credence to views widely held by many in the biomedical field that the currently promoted breast implants are nothing more than reissues of products commercialized more than four decades ago.

Innoval Failure Analysis
Ottawa, Canada K2A 2V1
August 2011