1963–1993: Device and Procedure Oriented Evolution

The silicone gel filled breast implant was introduced in 1963 by Drs Cronin and Gerow.² The author’s perspective based on personal clinical experience with breast augmentation began in 1977 as a plastic surgery resident. At that time, a majority of surgeons performed breast augmentation through an inframammary incision, placing smooth shell, silicone gel filled implants in a submammary pocket location. Capsular contracture rates were high (in the range of 10–15% or more in most practices), but were accepted by most surgeons and patients as an acceptable tradeoff of breast augmentation. Periareolar and axillary approaches to augmentation had been reported, but a majority of United States surgeons used the inframammary incision approach.

Cronin implants produced by Dow Corning Corporation in the 1960s were filled with a firm silicone gel. By the mid 1970s, the gel filler was changed to be much softer and more compliant, with a less highly cross-linked silicone gel. Shells were made thinner on most implants to decrease shell palpability for increased “naturalness”. Device failures were usually diagnosed at surgery to address grade 3 or 4 capsular contracture, because breast imaging with mammography was less common and less accurate, and an intact or disrupted implant was often impossible to differentiate on physical examination. At operation for failed devices, surgeons encountered a capsular space containing a very fluid silicone gel material, and surgeons sometimes concluded that the shell had disintegrated because it was very thin and sometimes exceedingly difficult to identify within the silicone gel filler as it was removed from the pocket.

Implant designs in the 1970s included round and shaped implants. Shaped implant designs were limited, and all shaped implants had smooth shells filled with very non-cohesive silicone gel. Shaped implants and some round implants were designed with patches of various materials on the posterior surface of the implant to encourage adherence of the posterior surface of the implant to the pectoralis major muscle or the chest wall, ostensibly to prevent future ptosis. Unfortunately, descent of the breast parenchyma and soft tissues while the fixed implant remained in place superiorly produced aesthetic compromises that resulted in fixation patches being removed from most implant designs by the mid 1970s.

Double lumen implants, with an inner lumen containing silicone gel and an outer lumen to accept relatively small volumes of saline, were also available during the 1970s and 1980s. To attempt to reduce rates of capsular contracture, some surgeons placed steroids in a small volume of saline in the outer lumens of double lumen implants. While steroids placed in the periprosthetic pocket prior to incision closure predictably resulted in significant soft tissue thinning in the inferior pole of the breasts and a high incidence of implant extrusions, steroids in moderate concentrations (e.g. 20 mg of methylprednisolone in 20 cc of saline) placed in the outer lumen of double lumen implants did not produce significant tissue thinning and may have been partially effective at reducing capsular contracture.

In 1981, a fluorosilicone barrier layer was added to the interior walls of implant shells filled with silicone gel in an attempt to limit diffusion of low molecular weight silicone through the implant shell (silicone bleed). This barrier layer, the Intrasheil® barrier, was developed by McGhan Corporation and subsequently licensed to Mentor Corporation for use in their implants. During the 1980s, both McGhan and Mentor Corporations modified shell designs by making shells thicker in an attempt to increase shell longevity.

Other implant designs were introduced in the 1980s, including polyurethane covered silicone gel filled implants (Vogue, Meme, and Replicon). All polyurethane covered implant devices were subsequently withdrawn from the United States market due to questions about the possible carcinogenicity of breakdown products of the polyurethane and a high failure rate of the devices due to thin shells and underfill relative to mandrel volume. Misti Gold breast implants (Bioplasty, St Paul, Minn.) filled with polyvinylpyrrolidone (PVP) hydrogel were introduced in the late 1990, but were subsequently withdrawn from the United States and British markets when osmotic effects of the hydrogel resulted in marked volume increases in the device post implantation.

The 1976 Medical Device Amendments to the Federal Food, Drug, and Cosmetic Act required manufacturers of medical devices to demonstrate a reasonable assurance of safety and efficacy for certain medical devices, and gave the FDA authority over those devices. Breast implants, however, were “grandfathered” into the regulatory process at that time, and manufacturers of implants were not required to provide the FDA with scientific evidence of product safety unless issues and questions arose about previously marketed devices. In 1991, prompted largely by questions about possible effects of silicone, the FDA published a new regulation that required breast implant manufacturers to submit premarket approval applications (PMAs).

In 1991, the FDA asked manufacturers to submit PMA data on their silicone gel implants. After examining the data, the FDA Advisory Panel concluded that insufficient scientific evidence existed to verify the safety and efficacy of silicone gel filled implants, but recommended the devices remain available to augmentation and reconstruction patients while studies accumulated more data. The FDA commissioner at the time, David Kessler, M.D., a pediatrician by training, overruled the panel and in April, 1992 called for a “voluntary moratorium” on all silicone gel implants from the United States market for primary breast augmentation. He allowed gel implants to remain available under adjunct study criteria for some reoperation patients and for reconstruction patients. No scientific data basis existed then or exists today to logically support the validity of that decision.

Several common themes exist in the history of the period from 1963 to 1993. Breast implant designs were largely derived from intuitive perceptions of individual surgeons or breast manufacturer personnel including bioengineers and, in many instances, marketing personnel. Most devices were used under Investigational Device Exemptions (IDEs) or 510k rules that allowed a new device to be classified as roughly equivalent to an existing device. These two sets of FDA rules were very lenient with respect to requiring substantive scientific data in large amounts under clinical review organization (CRO) supervision. As a result, surgeons and manufacturers became extremely complacent during this period and failed to accumulate enough valid scientific data with adequate followup to satisfy the requirements for an FDA PMA study which is the type of study required by the FDA to approve Class III devices such as breast implants.

Anecdotal reports about implant types and surgical techniques being published in the plastic surgery literature prior to 1992 did not fulfill the requirements for valid scientific studies according to FDA criteria, and when these data were submitted to the FDA, the FDA ruled that they were inadequate to establish safety and efficacy. Even in PMA studies structured by breast implant manufacturers, followup percentage was low, reoperation rates were extremely high within just 3 years following augmentation, documentation of study cases was poor, and CRO supervision pointed out discrepancies relative to the protocols.

The result was the commissioner’s “voluntary moratorium” on silicone gel breast implants for primary breast augmentation in the United States in 1992. Technically, the commissioner did not ban the devices, but asked for a voluntary moratorium on the use of silicone gel implants for primary breast augmentation. Right or wrong, silicone gel implants were no longer an available option for women desiring augmentation. Why and how did that occur?

The moratorium on gel implants for primary augmentation in 1992 resulted from three decades of complacency and business as usual by surgeons and breast implant manufacturers, not recognizing and prioritizing the importance of proactively designing and performing well structured scientific protocols with CRO supervision to assure collection of valid scientific data to address key questions of safety and efficacy. Instead of focusing on this priority, all existing companies during those three decades focused on marketing and remarketing similar implant designs under slightly different forms, calling them “new” products to make them attractive to the surgeon market (a practice that continues today). Not a single breast implant in the period from 1963 to 1991 was subjected to rigorous PMA testing to gather long-term data before the product was released and used in large numbers of patients. The results of this approach were: (a) many products had serious design flaws or high shell failure rates that became apparent after many devices had been implanted in patients (Vogue, Meme, Replicon, Misti Gold, Inamed Style 153, Mentor Siltex salines, PIP prefilled salines, peanut oil filled implants, and others), and (b) negative media and medicolegal consequences arose from untoward outcomes and the result of inadequate testing before bringing products to market. Patient advocate groups, patients, and the FDA became aware of this history and a pattern of introducing devices that had not been adequately investigated prior to market introduction. This awareness has prompted the FDA to be much more stringent with FDA PMA study requirements and require much more data, and longer term data before approving these devices. Although history was clear with respect to evolving concerns about implants prior to 1991, surgeons, surgeon professional organizations, and implant manufacturers did not proactively respond in an effective manner to establish scientifically valid safety and efficacy data for the devices that would satisfy public and FDA concerns about the devices. Had such data been available, the moratorium of 1992 and its effects on options for patients might well have been avoided.

1993–2006: Device and Technique Validation

The FDA commissioner’s “voluntary” ban of silicone breast implants for primary augmentation in 1991, overruling his own Advisory Panel’s recommendations, was a wakeup call for plastic surgeons and breast implant manufacturers. Surgeon professional organizations and their respective research entities responded by encouraging and funding more scientifically designed protocols to document improvement in quality of life following breast augmentation and verify critical issues of safety and efficacy of the devices. Surgeons and breast implant manufacturers immediately shifted focus from silicone gel to saline filled devices. Implant manufacturers instituted PMA studies for saline and silicone gel filled implants that embodied much more rigorous testing and better, more scientific study design with stricter monitoring by CROs.