Polyurethane (PU)-coated breast implants are a somewhat niche option in my practice, but they are useful occasionally. Here's what you need to know:
The Polyurethane Controversy
Polyurethane implants were first used in the 1960s and were heralded as a great advance, originally purported to have a "0% Capsular Contracture Rate!". As breast implant encapsulation was considered a major problem at that time, PU-coated implants were seen as a step forwards.
This did not last. The implants became very unpopular when it was found that one of its breakdown products – 2,4-TDA – caused cancer when injected into cancer-prone rats. A similar direct link has never been identified in humans, but based on this evidence PU implants were withdrawn from the US and UK markets.
Subsequent research found that the breakdown product 2,4-TDA is not detectable in human blood in patients with PU-coated implants. The US Food and Drug Administration stated that the risk of the implants causing cancer in humans was in the order of 1 in a million.
The added risk of developing cancer conferred by polyurethane implants is considered “remote but unquantifiable” by the MHRA (the UK body which oversees the safety of medical devices). A “Review of the Biological Safety of Polyurethane-Coated Breast Implants” conducted by the Medical Devices Agency in 2001 included amongst their conclusions that “Polyurethane-coated breast implants pose an unquantifiable (but probably low) carcinogenic risk. Since suitable alternative products are available, these devices should not be implanted.”
A review by the Committee on the Safety of Devices (CSD) concluded in 2003 that the benefits of polyurethane-coated implants did not outweigh their carcinogenic risk (despite that risk being unknown), therefore not recommending their reintroduction to the UK at that time. Nonetheless these implants were reintroduced in 2005, the MHRA noting that “As the implants are CE marked medical devices the MHRA accepts that they can legitimately be placed on the UK market, provided users and potential recipients are appropriately informed about their risks and benefits”.
As you can see, PU-coated implants are a somewhat controversial choice. I agree that most of the time there are equally good alternatives without the associated controversy, and for this reason I do not routinely offer this type of implant unless there are special circumstances.
Why consider PU implants?
Polyurethane implants are helpful in some particular circumstances, however. Firstly, they are associated with a very low rate of capsular contracture – scar tissue which can cause the breasts to harden or look and feel different. Capsule formation is unavoidable in breast augmentation surgery, and some patients present a particularly high risk of going on to form adverse capsular contracture. This includes patients who have developed ACC in the past, and those with predisposing conditions such as scleroderma. In those instances PU-coated implants may be suggested as an option for you.
Another useful property of PU-coated implants is the ingrowth of your tissue into the surface of the implant. This means the implant will not drop, rotate or migrate once positioned. In some people this is very useful - for instance, if they have previously had problems of this nature and implant pocket control is unusually difficult.
What are the downsides?
Asides from any (unproven) increased risk of developing cancer, the main disadvantages of polyurethane implants are their firmness and their technical difficulty in placement. There is a tendency towards excessively high implant placement that will not resolve spontaneously ("drop") in the case of PU implants, and the surgeon must actively make sure that they are not placed too high.
PU implants exhibit unique properties that make them an advantage in particular circumstances: they will not move from where they are placed, and their risk of developing adverse capsular contracture is probably the lowest of any available type of breast implant. That said, there remains debate about serious risk to health associated with their use. It is important that you are aware of this risk and make your own decision about whether this type of breast implant might be suitable for you.