The present review traces the evolution of breast implants over the past 50 years. During the early years (from 1951 to 1962), a number of different sponges were used for breast augmentation. The first of these was Ivalon, a polyvinyl alcohol sponge. Other sponges were introduced subsequently, including Etheron (a poly-ether sponge popularized by Dr Paule Regnault in Montreal) and Polystan (fabric tapes that were wound into a ball). Subsequently, polyethylene strips enclosed in a fabric or polyethylene casing were also used for breast augmentation. All of these materials had similar outcomes. Although the initial results were encouraging, within one year of augmentation, breasts became very firm and lost over 25% of their volume. This was due to capsular contracture, a process that would lead to the collapse of the sponge and would continue to plague plastic surgeons and their patients for the next 50 years. In 1963, Cronin and Gerow introduced the silicone gel ‘natural feel’ implant, which revolutionized breast augmentation surgery. Approximately 10 companies have manufactured many types of silicone gel breast implants over the years. They obtained their raw materials for gels and shells from a similar number of other companies that entered and left the market at intervals. Many of the suppliers and manufactures changed their names and ownership over the years, and most of the companies no longer exist. No formal process of United States Food and Drug Administration premarket testing was in effect until 1988. There have been three generations of gel implants and a number of other lesser variations. First-generation implants (1963 to 1972) had a thick gel and a thick wall. They have generally remained intact over the years. Second-generation implants (1973 to the mid-1980s) had a thin gel and a thin wall. They have tended to disrupt over time. Third-generation implants (mid-1980s to 1992) had a thick wall and a thick gel. Except for those made by Surgitek, these implants remain intact. The breast implant business was competitive and companies introduced changes such as softer gels; barrier low-bleed shells; greater or lesser shell thickness; surface texturing; different sizes, contours and shapes; and multiple lumens in search of better aesthetics. Ultimately, more than 240 styles and 8300 models of silicone gel breast implants were manufactured in the United States alone. Inflatable breast implants were introduced in Toulons, France in 1965 (the Simaplast implant). There have been three main eras of inflatable implants: seamed, high-temperature vulcanized and room temperature vulcanized implants. In 1973, spontaneous deflation rates of 76% to 88% over three years were reported for many types of inflatable implants. Because of this, most plastic surgeons abandoned their use. From 1963 until the moratorium on gel implants (January 6, 1992), about 95% of all breast implants inserted were silicone gel filled. Only 5% were saline filled. Since the moratorium, this ratio has been reversed and 95% of all implants have been saline-filled, with only 5% being gel filled. Polyurethane-coated (PU) silicone gel implants were introduced in 1968. Over the next 20 years, they were shown to reduce the prevalence of capsular contracture to 2% to 3%. Other forms of surface texturing (Biocell, Siltex, multistructured implant) also appear to reduce capsular contracture with gel implants, but the reduction has been much less dramatic than that seen with PU implants. Contoured (anatomical) shaping appears to have advantages in some patients with gel implants. No such advantage has been seen for texturing or shaping with saline-filled implants. The story of gel implants has culminated in the largest class action lawsuit in medical history, with US$4.2 billion being awarded to women with silicone gel implants. During the past decade, there has been a tremendous amount of research on the reaction of a woman's body to gel implants. A plethora of studies have demonstrated that silicone gel implants are not associated with the development of any medical diseases. Silicone gel-filled implants have therefore been approved for use under Health Canada's Special Access Program. Silicone gel-filled implants may now be used in certain patients in whom they would provide advantages over saline implants. Silicone gel implants have not been approved for unrestricted general use. The evolution of breast implants occupies the past half century. It has been a stormy course, with many exciting advances and many bitter disappointments. The universe of breast implants is large and the variation among the implants is substantial. The purpose of the present review is to trace the evolution of breast implants over the past 50 years.
Polyurethane-Coated Implants for Prevention of Double-Bubble Effect in Breast Augmentation
