Implant History I
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Implant History I
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History of Breast Implants – Part I
William P Adams, Jr. MD
Introduction The female breast has long been an object of both individual and societal interest. The breast represents a woman’s femininity and sensuality. One does not have to look far in the media to recognize the relative value of the breast in female perception by society. These factors represent some of the underlying motives that have made surgery of the female breast, both aesthetic and reconstructive, an area of great interest and formidable challenge to plastic surgeons for decades. Arguably no device or single surgical procedure has altered the landscape of breast surgery as dramatically as prosthetic breast implants. Breast implants have been in use for over 40 years, yet the topic still produces heated debate and emotions. On the surface it seems odd that a device that has been in use for over 40 years is still fighting for FDA approval. This review will include 2 parts and will help to outline the past development of breast implants and their present and future status.
Silicone The
building block of the breast implant is based on silicone science and the
biochemical principles are essential for developing implant technology.
Silicone refers to a group of polymers, based upon the element silicon. Sand
(Silicon dioxide (Sio2)) is one of the most abundant compounds on earth. The
polymer utilized medically is poly-dimethylsiloxane (PDMS).
Silicones were first widely utilized in the World War II era for industrial and military application. Medical applications for silicone were quickly identified and silicone products are commonplace within the medical industry today. Common silicone containing products include indwelling catheters, extended wear contact lenses, pacemakers, syringes, and pharmaceuticals. Silicone products include industrial and medical grade materials. Medical grade refers to material that is pure and consistent in composition. Silicone is classified as a medical device meaning that silicone does not achieve its primary intended purpose by chemical action or through its metabolism. Characteristics of silicone that are favorable for medical uses include thermal and oxidative stability; chemical and biological inertness; hydrophobic nature; and sterilization capability. Silicone polymers may be produced in a variety of forms including oil, gels, or elastomers (rubber). The physical state is determined by the degree of chemical cross-linking. Cross-linking occurs between vinyl and hydrogen groups on silicon atoms. Silicone oils are straight chains of PDMS without cross-linking and are insoluble in water. PDMS will remain in liquid form indefinitely. Silicone gels consist of cross-linked (of various degree) PDMS chains together with variable amounts of PDMS liquid. It is important to keep in mind that the majority of silicone gel is silicone oil within the confines set by the PDMS gel matrix. The ratio of silicone liquid to gel is controlled by manufactures to control the viscosity of the gel. Elastomers of silicone have high degrees of cross-linking and almost no PDMS oil. Breast implant shells, both silicone and saline filled, consist of a vulcanized silicone elastomer that is reinforced with silica for increased strength.1 In an effort to reduce gel bleed from silicone filled devices, phenyl or triflouropropyl groups are bonded to the shell to decrease the shell permeability to PDMS oil.2,3 These “low bleed” implant shells with “barrier coating” are characteristic of current 3rd ,4th and 5th generation implants (discussed later). Manufacturing and Materials Prior to the development of prosthetic breast implants numerous materials were trialed for the purpose of augmenting the female breast. Up until the 1950’s materials included autogenous fat and dermal grafts, fat injections, paraffin injections, insertion of glass balls, ivory, rubber, and terylene wool.4,5 These materials frequently led to infection, tissue necrosis and firmness of the breast. The autogenous materials were uniformily troubled by resorption. The 1950-1960’s saw the use of many other products. Free injections of hydrocarbons, petroleum jelly, silicone oils, vegetable oils and bees wax were tried and led to many problems including infection, granulomas, fistulas and breast firmness.4,5 During this same time many different types of sponges were developed hoping that soft tissue ingrowth would improve the biocompatibility of these products. Polyvinyl and polyether were the most common sponge materials (figure 2) others included silastic and Teflon. Unfortunately these products were complicated by many of the same problems and were discontinued. The development of the silicone gel prosthesis in 1962 marked a very important new era in breast surgery. Since Cronin and Gerow6 first reported its use very few other materials have been used for breast augmentation. This is partly due to the success of silicone devices and also by the subsequent FDA regulation of medical devices that was started shortly after the development of silicone gel devices. Fewer materials has not equated to fewer devices. It has been reported that more than 200 different types of silicone breast implants and expanders have been manufactured in the United States.7 Since the original Silastic gel implant was produced many modifications have been made to the design of these devices. The evolution in design and manufacturing of breast implants has focused on four major areas: characteristics of the shell, characteristics of the filler, shape, and surface configuration. Any device can be expected to perform different from its counterparts based on its physical and structural properties, and therefore presents a significant challenge when we attempt to retrospectively review the outcomes of breast implant surgery over the last 40 years. To assist in this review, attempt has been made to classify breast implants into generations based on the time period of their development.8-11 This classification system recognizes the evolution and variations in the design that have occurred over time; however, it does not provide the ability to compare outcomes of breast implant surgery based on the time period the surgery was performed. Large overlaps of the periods of manufacturing of a particular device and the continued clinical use of those devices into the period of the next generation of manufacturing prevents this concept from having clinical applicability. Next time we will review the different generations of breast implants and what the relevance is for current patients seeking breast augmentation or breast enlargement, breast augmentation revision, and breast lift with implants.
Bibliography 1) Brody GS: On the safety of breast implants. Plas Reconstr Surg 100:1314, 1997. 2) Barker DE, Retsky MI, Schultz SL: The new low bleed mammary prosthesis: An experimental study in mice. Aesthetic Plast Surg 5:85, 1981. 3) Caffee HH: The influence of silicone bleed on capsular contracture. Ann Plast Surg 17: 284, 1986. 4) Institute of Medicine: Bondurant S, Ernster V, Herdman R (eds): Safety of silicone breast implants. Washington, DC, National Academy Press, 2000. 5) Young VL, Watson ME: Breast implant research: Where we have been, where we are, where we need to go. Clinics Plas Surg 28(3):451-483, 2001. 6) Cronin TD, Gerow FJ: Augmentation mammaplasty: A new “natural feel” prosthesis. Transactions of the Third International Congress of Plastic Surgery, Oct. 13-18, 1963, Amsterdam, The Netherlands, Excerpta Medica Foundation, 1963, pp 41-49. 7) Middleton MS McNamara MP Jr: Breast implant classification with MR imaging correlation. Radiographics 20:E1, 2000. http://ej.rsna.org/ej3/0112-99.f in/. 8) Peters W, Smith D, Lugowski S: Failure properties of 352 explanted silicone gel breast implants. Can J Plast Surg 4:55-58, 1996. 9) Rohrich RJ, Adams WP Jr, Beran SJ, et al: An analysis of silicone gel-filled breast implants: diagnosis and failure rates. Plas Reconstr Surg 102:2304, 1998. 10) Feng L-J, Amini SB: Analysis of risk factors associated with rupture of silicone gel breast implants. Plas Reconstr Surg 104:955, 1999. 11) Holmich LR, Kjoller K, Vejborg I, et al: Prevalence of silicone breast implant rupture among Danish women. Plas Reconstr Surg 108:848, 2001.
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For further questions or to schedule a consultation call 214-965-9885 or email Dr. Adams. Dallas plastic surgeon offers plastic surgery procedures - forehead lift, browlift, breast augmentation using saline breast implants, silicone breast implants, cohesive gel breast implants, Gummy-bear breast implants, liposuction, rhinoplasty and more to Dallas, Ft. Worth, Austin, Houston and surrounding areas.
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