Types of breast implants

Breast implants consist of a filler material inside a silicone elastomer shell. The shell can be either smooth or textured. Some are covered with a polyurethane foam coating. Only two types of breast implant filler are currently in use in the UK:

• silicone gel
• saline.

Silicone

Silicone gel breast implants were first introduced in around 1962, when there were no specific statutory regulations in place to control the marketing and use of medical devices in the UK, the rest of Europe, or in the USA. Since then, the use of breast implants has increased gradually and it is now estimated that over 10,000 people receive breast implants each year in the UK, 80% of these opting for silicone gel-filled implants. Department of Health policy on the supply of breast implants is based on the principle of evidence based medicine and, where appropriate, reflects conclusions drawn by groups of independent experts. Currently only breast implants filled with silicone or saline are available for use in the UK.

PIP implants

A brand of silicone breast implants that was available until March 2010.

Background

On 29 March 2010, the French medical device regulatory authority (AFSSAPS) informed the MHRA that it had suspended the marketing, distribution, export and the use of silicone gel filled breast implants manufactured by PIP (a French breast implant manufacturer). They also recalled all of these devices in France. Following an inspection of the PIP manufacturing plant, AFFSAPS established that breast implants manufactured since 2001 had been filled with a silicone gel with a composition different from that approved.

The MHRA issued a Medical Device Alert (MDA/2010/025) on 31 March 2010 advising UK clinicians not to implant these devices. We also produced a set of questions and answers for members of the public. On 04 October 2010 we issued a further Medical Device Alert (MDA/2010/078) advising UK clinicians on the clinical management of women implanted with PIP silicone gel filled implants.

In April 2010, AFSSAPS initiated testing of affected implants to look at the genotoxicity (potential for cancer), chemical toxicity and irritation to biological tissues. In addition, mechanical testing of the implant shell was carried out. At the end of June 2010, AFSSAPS told the MHRA of delays to their product testing. Because the MHRA was aware of the concerns of implanted women, it decided to commission some limited testing to obtain an early indication of genotoxicity or chemical toxicity. It was recognised that these were not as extensive as the tests being carried out in France, but it was agreed with the relevant experts on the Committee on the Safety of Devices that these would give very good early information on whether there was a safety problem with the filler material.

In early September 2010 the MHRA announced encouraging results of the UK testing (26Kb), with no evidence of safety issues associated with the filler material.

On 28 September 2010 AFSSAPS published a statement with the findings of their results (external link). The French results confirmed the UK findings reported at the beginning of September 2010 that there is no evidence of genotoxicity (potential for cancer) or chemical toxicity of the filler material in the implants. Mechanical testing of the implant shells carried out by AFSSAPS also suggested that there may be an increased risk of rupture. The AFSSAPS provided a summary of the tests that they had conducted in their topical report dated June 2011. An English version of this report is available on the AFSSAPS website:

Topical report: PIP silicone gel pre-filled implants (external link)

The Therapeutic Goods Administration (TGA) of the Australian government also carried out tests on PIP breast implants. They concluded that these implants conformed to the relevant international standards for this type of product including those for gel cytotoxicity and shell strength. On 12 January 2012 the TGA published a summary report of their findings from the tests they conducted on 7 April 2010. A report of findings is available on the TGA website (external link).

The MHRA has set up a toxicology chemical expert group to establish whether, and to what extent, ‘industrial grade’ silicone used in PIP breast implants may be associated with increased health hazards compared with conventional ‘medical grade’ silicone.

Testing being carried out under this group's advice will:

• Establish the composition of a series of unused PIP breast implants that differ with respect to batch number and expiry date.
• In parallel conduct identical analyses with batches of legitimate unused breast implants that contain medical grade silicone.
• These analyses are designed to establish: (a) whether and in what way PIP breast implant silicone differs from medical grade silicone, and (b) whether there exists inter-batch variation with regard to the composition of PIP breast implant silicone.
• If there is evidence for inter-batch variation we will also establish whether there exists intra-batch variation in PIP breast implant silicone
• Depending upon the above results the need for additional toxicity testing will be considered.
• Factors that will influence decisions regarding the need for additional testing will be: (a) evidence for the presence in PIP breast implant silicone of materials not found in medical grade silicone, or that are present in PIP breast implant silicone at significantly higher concentrations, (b) the presence in breast implant silicone of known toxicants, (c) the results of additional testing being commissioned currently by the TGA in Australia.
• The objective of this programme is to establish whether exposure to breast implant silicone poses human health risks.

Breast feeding and PIP implants

The MHRA has consulted clinical experts regarding the risk to infants from PIP silicone gel breast implants in women who are breast feeding. It was considered that PIP silicone gel breast implants would not pose any significant risk. There is also no evidence of any harm to breast feeding infants in women who may have experienced ruptures in their PIP implants. Women and implanting surgeons are encouraged to continue reporting all adverse events involving breast implants to the MHRA adverse incident centre.

Saline

Saline-filled breast implants consist of a silicone elastomer shell, which is filled with saline solution (salt water). There are no restrictions on the sale or use of CE-marked saline-filled breast implants in the UK.160;

Polyurethane coated implants

Polyurethane-coated silicone gel breast implants are now available for implantation in the UK. These implants consist of a silicone elastomer shell filled with silicone gel. The shell is coated with a polyurethane foam which breaks down over time. Polyurethane-coated breast implants were removed from the UK market in 1991, following concerns about the possible carcinogenic risk from the polyurethane breakdown product.

The Committee on Carcinogenicity* concluded that carcinogenic risk from these implants is small and unquantifiable. In April 2005, the manufacturer of one type of polyurethane-coated breast implant reintroduced them to the UK. The manufacturer claims that the incidence of capsular contracture is lower than with other types of breast implant, and that the movement or rotation is less. In April 2005, the MHRA issued a letter to the plastic surgery professional bodies (35Kb) to bring this issue to their attention and to inform them of the risks and claimed benefits.

Associated information: accompanying patient information sheet (21Kb); a review of the polyurethane breakdown product (287Kb) carried out by the MHRA in 2001; the paper presented to the Committee on the Safety of Devices (CSD) (84Kb) in November 2003; minutes from the November 2003 CSD meeting (34Kb).

 *The Committee on Carcinogenicity of Chemicals in Food, Consumer Products and the Environment (COC) provides expert advice to the Chief Medical Officer and UK Government Departments.

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The following types of implant are not available in the UK:

• hydrogel-filled
• soya bean oil-filled (Trilucent™)
• implants with a titanium coating.

Hydrogel

This type of implant consisted of a silicone elastomer shell containing hydrogel filler. Hydrogels are polymeric materials that have the ability to swell in water without dissolving and retain water within their structures.

Until December 2000, there were two models of hydrogel filled breast implants on the UK market – PIP Hydrogel and NovaGold. Because of continuing concern over the safety of breast implants, the Medical Devices Agency (a forerunner to the MHRA) carried out a series of investigations into the safety of the various filler materials used in the implants available in the UK. The agency's investigations into hydrogel-filled breast implants revealed inadequacies in the manufacturers' biological safety assessments and concluded that there was not enough information to fully assess the safety of either of the hydrogel filler materials. When they were made aware of the results of these reviews, both manufacturers decided to withdraw their hydrogel-filled breast implants from the UK market in December 2000 as a precautionary measure, pending further studies to establish the safety of the filler materials. The Medical Devices Agency issued two alerts at the time: DA 2000(07) - Breast Implants: PIP Hydrogel and DA 2000(08) - Breast Implants: NovaGold.

It must be emphasised that no definite risk has been identified. The concern lay only with the way the safety of the hydrogel fillers had been assessed. The MHRA is continuing to monitor the safety of these implants and, based on the currently available evidence, does not recommend that women with hydrogel-filled breast implants have them removed unless they are experiencing problems. Women who think that they may have hydrogel breast implants and are concerned, should contact the surgeon who carried out their operation. Clinicians and members of the public should continue to report adverse incidents to the MHRA.

Soya bean oil (Trilucent™)

These implants were removed from the market in 1999, and in 2000 the Medical Devices Agency (a forerunner to the MHRA) recommended that these implants should be explanted. A clinical research programme was sponsored by AIE Inc and was carried out by an independent panel of experts to investigate the long-term health effects of Trilucent implants. This was completed in 2004. The report (354Kb)  concluded that there is no evidence for local or systemic disease risk once the implants have been removed. The MHRA issued an alert (MDA/2004/047) in September 2004 to notify interested parties of the conclusions of this study and of the closure of the Trilucent Care Centre (TCC), which had been set up for patients with these implants. The MHRA continues to record and investigate reports of adverse events associated with Trilucent breast implants. If further problems are identified, we will issue advice.

Background information

Trilucent breast implants were on sale throughout the EU between 1995 and March 1999. They consisted of a silicone elastomer shell with a lipid filler based on soyabean oil. Since they were first marketed in 1995 over 9,000 implants were sold in the UK, and implanted into almost 5,000 women. As a result of an investigation into reports of inflammation associated with rupture of Trilucent breast implants, the Medical Devices Agency reviewed the manufacturer's safety assessment. This revealed serious concerns relating to the long term safety of the breast implants, in particular in relation to the breakdown of the lipid filler. As a result of the agency’s concerns the company voluntarily withdrew the product from the market in March 1999 and the Medical Devices Agency issued Advice Notice AN 1999(01). The withdrawal was a precautionary measure until further information could be gathered about the biological safety and clinical experience with these implants. The advice given at that time was that there was no evidence to suggest that removal of Trilucent breast implants was indicated but that women should be advised to seek an immediate consultation if they noticed unusual breast swelling or inflammation associated with their Trilucent breast implants.

The first results of further analytical studies on the filling material in Trilucent breast implants became available in May 2000. The Medical Devices Agency convened a group of independent experts (the Trilucent Advisory Group) to consider the available scientific evidence. This group made an assessment of the risk to women with these implants and provided advice to the Medical Devices Agency. A statement  (25Kb) summarising the Trilucent Advisory Group's conclusions and advice is available, with the minutes of a meeting (33Kb) held on 19 May 2000. Based on this advice, the Medical Devices Agency issued Hazard Notice HN 2000(05). In 2000, a programme of research was initiated to investigate the risks to women implanted with Trilucent breast implants. This programme was directed, on behalf of AEI Inc, by a panel of independent experts. The programme was completed in 2004. The panel concluded that:

• the recommendation that Trilucent breast implants should be removed remains appropriate because exposure of local tissue to toxic compounds has been confirmed
• there is no evidence for local or systemic disease risk once the implants have been removed
• no further studies are needed to assess the potential risk of Trilucent breast implants.

This information was the subject of MHRA Medical Device Alert MDA/2004/047.
Further to the completion of the research programme, the manufacturer agreed to provide the MHRA with six-monthly reports of adverse incidents involving Trilucent breast implants until 2009. The MHRA has reviewed the manufacturer’s reports and reports received from other sources over the period 1999-2009 and has seen:

• no evidence of cancer or increased risk of cancer or reproductive toxicity
• a decrease in the number of reports received annually since 2006.

The MHRA continues to record and investigate reports of adverse events associated with Trilucent  breast implants. If further problems are identified, the MHRA will issue advice.

Titanium coated

These implants are made from a silicone gel filler with a titanium coated silicone elastomer shell. The only model of titanium-coated breast implant known to have been CE marked was the TiBREEZE implant manufactured by GfE Medizintechnik GmbH in Germany. These implants were filled with silicone gel material manufactured by Poly Implant Prothese (PIP).

TiBREEZE implants were recalled from the EU market in 2004. All but four of the implants supplied to the UK were returned to the manufacturer and therefore might have been implanted into UK patients.