Helmer, Kim L Misra,
Amit Sridharan,
Srikesh
Silicone
Implants
Introduction
In the 1940’s Japanese prostitutes had their breasts injected with substances such as paraffin, sponges, and non-medical grade silicone to enlarge their breasts. This was done by the fact they thought American servicemen favored woman with large breastsVII. In the 1960’s breast implants became popular with the use of medical grade silicone implants. Reasons for these implants varied from medical conditions to personal well being. A silicone implant is a sac (implant shell) of silicone elastomer (rubber), which is surgically implanted under the chest tissues, and then filled with saline, a salt-water solution, through a valve I.
Since the time silicone implants became widely used, there were the obvious advantages for this procedure, but all being of self-preference, not a life threatening need. In the beginning breast implants using silicone had few disadvantages, for both women and men were willing to take the risks. Not until the 70’s did noticeable problems became apparent with the use of implants into the body.
With increasing complaints from people with silicone breast implants, companies such as Dow Corning, Bristol Meyers-Squid and Boiplasty faced a serious problem. Each of these companies faced a series of individual lawsuits. Dow Corning was the leading producer of silicone implants therefore they were hit the hardest from these lawsuits. In the end this lead to the stop of using silicone filled implants and the bankruptcy of Dow Corning.
History
Silicone is a synthetic plastic, or
polymer, that was first developed in the 1930s. Silicone has been used for
medical purposes like artificial joints, pacemakers, artificial heart valves,
hypodermic needles and so on for over 50 years. In the late 1940s physicians
began to inject silicone liquid directly into the body to fill out certain
parts, including the face to smooth out wrinkles and the breast to make them
largerIV. In 1962, Dr. Thomas Cronin and Dr. Frank Gerow, two
cosmetic surgeons from Huston, Texas, were the first physicians to insert a
silicone gel for breast implants in a patient. Dow Corning developed the first
generation implants as a commercial product along with some other
manufacturers, including Bristol Meyer Squid and Bioplasty in the late 1960’s.
These implants constituted of a thick silicone shell and had a high rate of
silicone gel bleed bleeding. For these implants, it required several large
surgical incisions, which often left women with prominent scarsIV.
During the late 1960’s and 1970’s, a second generation implants were introduced
with a thinner silicone shell but no improvement in the gel-bleeding rate. The
third generation implants had a thick silicone shell and much lower rate of gel
bleed.
Silicone
Implants
Silicones are inorganic polymers, that is, there are no carbon atoms in the backbone chain. The backbone is a chain of alternating silicon and oxygen atoms. "Polysiloxane" is the proper name for silicones. But when they were discovered it was thought that they had "silicone" groups in the backbone chain. When the real structure was discovered, it was too late, and the name stuck. Silicones vary in their composition and this is dependant upon the length of the polymers as well as the organic
grouping in the side chains.
Therefore silicone can have the consistency of fluid, oil, gel or rubber. There
are three basic types of implants; silicone gel-filled, saline-filled and a
combination of the twoIV. The most important things used in medical
implants are fluids, gels and rubbers (elastomers) whose physical and chemical
properties include, amongst others, a high degree of chemical inertness,
thermal stability and resistance to oxidationII.
Silicone-filled implants
consist of an elastomer envelope per-filled with a clear, sticky, thick
jellylike form of silicone that closely approximates the consistency of breast
tissueIV. Silicone fluids are usually linear chain of
polydimethylsiloxane (PDMS), which have a wide range of chain lengths and
molecular masses. Silicone gels have lightly cross-linked polysiloxane
networks, swollen with PDMS to produce a cohesive mass. The PDMS is not
chemically bound to the cross linked network but is retained only physically.
Silicone elastomers are extensively cross-linked and contain little free PDMS
fluid. Linear polydimethylsiloxanes of molecular weight exceeding 500,000 are
of particular interest as they form the basis of silicone rubber. Adding
amorphous silica to it may increase the tensile strength and tear resistance of
silicone elastomers II.
The properties that make
silicones the perfect candidates for implant material are
(i)
The chemical stability associated with their structure and
desired properties are considered impossible to be degraded in a biological
environmentV.
(ii)
Silicones can be readily sterilized without destroying their
physical properties also contributes to its choice as implant material.
(iii)
Silicones make good elastomers because the bonds between a silicon atom and the two oxygen
atoms attached to it are very flexible. The angle formed by these bonds can
open and close like a scissors without much trouble. This makes the whole
backbone chain flexible.
(iv)
Silicone implants do not wear out. If you
have an implant it will only be necessary to change it if you put on or lose
weight or develop a capsular contracture (formation of tough, fibrous tissue
around the implant), which may cause problems.
Silicone-based polymers are
made by the polymerization of monomers, which are called silanes. These silane
monomers do not polymerize by the traditional addition and condensation
polymerization methods typical of carbon based monomers. Rather, some unique
reactions are used to form silicone-based polymers called silicones. With appropriate formulation, the chemical
properties of silicones remain virtually unchanged for a very long period of
time.
No link has
been found between silicone implants and cancer in humans. Used extensively in
medical applications, silicone rubbers have caused no adverse health reactions
in clinical testing or field application. Used extensively in medical
applications, silicone rubbers have caused no adverse health reactions in
clinical testing or field application.
Advantages
Approximately 80% of the implant surgery
is performed on women to augment their breast; 20% is performed as breast
reconstruction to replace a breast lost to cancer surgery. The reasons that
women have implants are to change their particular situation and improve their
quality of their lifeIV. Breast implants can bring psychological
benefits for women who feel that their breasts are unwomanly and inadequate.
They can help restore self-esteem and improve the quality of life. The ASPRS
survey found that women who had their breasts reconstructed after cancer
surgery listed three desires as their primary reasons for choosing implants; to
free them from the need to wear an external prosthesis (90%), to help them
forget about the state of their health (80%) and to help them feel whole again
(75%)IV.
The ASPRS survey found that women who had
their breasts reconstructed after cancer surgery listed three desires as their
primary reasons for choosing implants:
§
To free them from the
need to wear an external prosthesis (90%)
§
To help them forget
about the state of their health (79%)
§
To help them feel
“whole” again (75%)
The survey also found that most of the
expectations were metV.
Disadvantages
Besides the obvious advantages to
implants there are a few complications associated with this procedure.
Undergoing any surgical procedure involves a risk of complications, such as,
the effect of anesthesia, infection, swelling, redness, bleeding, and pain. It
has been proven that pure, medical grade silicone is inert, chemically and
physically stable during contact with body tissues. Investigation of silicone
implants has never found evidence of the association of silicone with cancer or
rheumatic diseases. There are potential complications specific to silicone
implants:
(i)
Leaking or Rupture
(ii)
Capsular Contracture
(iii)
Interference with mammography and cancer detection
(iv)
Hematoma or Seroma
(v)
Necrosis.
All these
complications are not due to the polymer itself but due to the reaction that
the body makes to foreign substances present in our body.
The implant’s outer envelope may break, or rupture, due to the trauma or injury (such as in a car accident) or normal wear and aging. In a silicone gel-filled implant, this would allow the gel to escape the sac of the implant and possibly seep/leak into the surrounding tissue or migrate to other parts of the body. A rupture in a silicone gel implant can be intracapsular (the scar capsule surrounding the implant stays intact, containing the gel for the time being) or extracapsular (the scar capsule breaks and the gel escapes into nearby or distant tissues).
The problem associated with
this type of complication is that the gel from the broken implants may migrate
outside the capsule and create lumps called granulomas in the nearby tissue in
the chest. It may also cause a condition called lymphadenopathy, where free
silicone causes lymph nodes in the armpits to enlarge.
As a natural reaction to something foreign, such as an implant, being inserted, the body forms a protective membrane of scar tissue around the object. This layer of tissue normally shrinks to some degree against the implant. However, in a number of women the capsule of scar tissue may tighten too much. This Contracture squeezes the implant and, as a result, the breast feels firmer and may be uncomfortable. In severe case the contracture is quite painful.
The problem associated with this type of complication is that the contracture may squeeze the implant so tightly that it may rupture or extrude through the skin. It also affects the ability to detect breast cancer, either by physical exam or mammography.
Breast implants are known to interfere with mammograms and cancer detection. There is evidence that silicone gel can decrease the chance of early detection of breast cancer and thus lessen the chance of a cure. All implants are “radiopaque” i.e. they block the mammography X-ray beam as it passes through the breast, obscuring the tissue in the front of and behind the prosthesis.
As a result small tumors remain hidden and undiagnosed. Breast implants mechanically squeeze surrounding breast tissue increasing tissue density and making it difficult to detect small abnormalities and subtle distortions, which are often first clues to breast cancer. The scarring caused during the surgery leads to distortions, calcifications visible on the mammogram or felt during a physical exam. Such benign abnormalities may be confused with cancer; cancerous abnormalities may be assumed to be benign.
In some women, calcium forms in the tissue surrounding the
silicone gel implant. Like capsular contracture, this may cause hardening and
pain. Since microcalcification is a possible indicator of early breast cancer,
calcium deposits caused by implants may raise unnecessary alarm, and
unnecessary biopsies may be performed to determine whether the deposits are
cancer related. The cause of calcification is unknown, but it appears to be
part of the process of scar formation, and the risk varies according to an
individual’s biochemistry.
Concerns
Most of the
health concerns about breast implants are related to silicone. Even if a
silicone gel-filled breast implant does not rupture, small amounts of the
silicone gel may migrate (“bleed” or “sweat”) out of the implant into the
surrounding tissue. There has been continuing concern that this escape of
silicone may cause harmful effects, including connective tissue and related
disorders and cancer.
One of the major myths of silicone
implants is that they could cause or influence the progression of cancer. At
this point there is no scientific evidence that silicone gel-filled breast
implants can increase the risk of cancer in women, but we can’t completely rule
out this possibilityVI. A
study conducted by Los Angeles County found that there is no increase in breast
cancer for women with implantsV.
Another concern about silicone implants is that it may lead to autoimmune diseases. Immune diseases are diseases in which a human body’s immune system mistakenly attacks the body’s own cells, destroying healthy tissues. It is believed that in rheumatic diseases the immune system attacks muscles, joints, nerves, connective tissue and bones. Some women with breast implants have experienced disorders, as well as a variety of symptoms that could be related to the immune system. However, symptoms such as these may be present in persons without connective tissue disease, or without breast implants. So it is unclear as this time whether the signs and symptoms experienced by these women are related to their implants. In some cases, women have reported a reduction in symptoms after the implants were removed and in other cases there was a change in symptoms after the implants were removed.
The children of implanted women were found to suffer from swallowing difficulties, irritability, skin rashes, fatigue. It was believed that the high level of silicone found in breast milk could be transferred to the newborn childIII. In a June 21, 1999 study, the Institute of Medicine of the Academy of Science conducted a two-year investigation on the possible involvement of silicone gel implants in systemic and connective tissue disease. They reported that there is no danger in breast-feeding after implants. Cows milk and infant formulas have a far higher level of silicon, a silicone component, than mother’s milk. In terms of risks to the baby, neither silicone nor saline are in the milk, so the baby should not experience any problems due to the implants. Overall, it appears that breast implants themselves do not have negative consequences in breast-feeding. However, the surgery is the main cause for concern because of the risk of severing milk ducts or disruption of important nerves responsible for triggering milk productionIV.
Companies involved in the production of
silicone breast implants.
In the 1960’s Dow Corning was the leading producers for breast implants. At this time, Dow Corning had improved the tactile properties of their breast implant device by eliminating the seam of the sac and made the outer sac thinner. They also reduced the handling time of the implant during surgery by decreasing the viscosity of the silicone fluidVI. During these improvements Dow Corning was responsible for the safety studies of the improved implants. From these studies it was found that a lower viscosity of the silicone would migrate through the sac of the implant to lymph nodes were the body would eliminate it. There were no signs of increased migration of the silicone than from previous implants. In 1976 the Federal food and drug administration required proof of safety on of the implants. The FDA was accused of “grand fathering” silicone implants believing that the ten year history of existing implants proved its safetyVI.
In 1977 a woman from Cleveland won claims against Dow Corning, saying that ruptured implants caused pain and suffering. She received $170,000 in compensation this was the first of the ending of silicone breast implants. In 1982 a woman won $2 million from California. She claimed that she developed systematic autoimmune disease caused by her implantsVII. In 1991 Alabama women won $5.4 million from Boucher Heyer-Shuttle for preliminary symptoms of autoimmune disease. A California woman won $7 million for a ruptured implant. In 1991 Dow Corning gave the FDA the results of 329 studies on silicone breast. FDA appointed an independent panel of specialist to review the studies. The results of the FDA panel showed disappoint of the safety studies of Dow Corning, Mentor, McGhan & Bioplasty. At this time the FDA called for a voluntary withdrawal of implant procedures except for reconstruction.
By December 91, 137 individuals lawsuit were filed against Dow Corning. In 1992 a class action suit was filed to save time on retrieving any money if the case was won.
By 1992 the number of lawsuits increased from 137 to 12,359. In 1994 this number was almost at 20,000 lawsuits.
Dow Corning filed for chapter 11, bankruptcy, in 1995. At this time 410,000 potential claims existed. In 1995, since the class action suit was filed against the suit raised to 400,000 clients. By filing chapter 11, this slowed down other proceeding against Dow Corning. In the mid 1998, a federal judge approved Dow Corning Corp.’s $4.5 billion plan to emerge from bankruptcy, including $3.2 billion to settle the class action lawsuit that claimed the company’s silicone breast implants made thousands of women sick. This didn’t take away the rights of the individuals’ lawsuit against Dow Corning. This was unfortunate for Dow Corning because in December 1998 a court appointed scientific panel that agreed that there were no proven links of diseases and implantsVI.
Reference
I www.fda.gov/cdrh/breastimplants/labeling/mentor_patient_labeling_5900.html
II www.silicone-review.gov.uk/silicone/index.html
III www.silicone-review.gov.uk/children/index.html
IV http://biomed.brown.edu/Courses/BI108/BI108_2000_Groups/Breast_Implants/ pages/breastfeeding.htm
V Nancy Bruning, “Breast Implants: Everything you need to know,” 2nd ed., Hunter House Inc., 1995
VII http://www.fda.gov/cdrh/breastimplants/indexbip.html