Regulatory requirements for breast implants

The European Medical Device Directive (93/42/EEC) starts from the premise that no medical procedure can be without risk and that an appropriate level of safety must be achieved by balancing any risks associated with the use of a medical device against anticipated benefits to the patient. The regulations do not require the absence of all risk. This would be impossible either to achieve or to prove. Instead they require that any risks must be compatible with a high level of protection of patient health and safety. Where risks cannot be eliminated, users must be advised by the manufacturer of factors that are relevant to the professional judgements they have to make. In the case of breast implants, this advice would include information on potential health hazards, expectations about device performance (including expected lifetime) and other information that may be relevant to consent.

Further details on the Medical Device Directives can be obtained from the MDA (now MHRA) website.

The Medical Device Directives specify Essential Requirements for safety and performance that all medical devices must meet. One means by which conformity with the Essential Requirements may be demonstrated is by compliance with relevant and appropriately authorised standards. The relevant European standards for breast implants include generic standards for risk analysis, evaluation of biological safety, sterilisation and non-active (i.e. non-powered) surgical implants, together with a more specific standard for mammary implants.

General requirements
The European standard for risk analysis (EN 1441) requires identification of all potential hazards and the estimation and analysis of the associated risks.

The European non-active implant standard (EN ISO 14630) requires the intended performance of an implant to be defined and documented. It also lists a number of safety related design attributes which need to be documented and evaluated to demonstrate that the medical device performs as intended.

The sterilisation processes are required to be validated and controlled in line with the appropriate sterilisation standards.

The biological safety needs to be evaluated in line with the principles of the appropriate standards for biological evaluation. This involves identification of all potential toxicological hazards, an evaluation of the available data on the toxicity of the implant material and its components and when necessary appropriate biological tests.

Specific requirements
The draft European breast implant standard (prEN 12180) specifies additional design attributes which need to be addressed for breast implants and specifies tests for material and implant strength. The mechanical testing requirements in this and other breast implant standards are based upon information on forces expected to be encountered in normal use and under exceptional but foreseeable conditions. The base dimensions, anterior projection and nominal volume must be defined and included in the labelling.

Tests required specified in prEN 12180
Mechanical testing of the intact device
The abrasion test involves placing the breast implant between two plates, one plate moves rubbing on the surface to simulate folds in the implant with silicone rubbing against itself.

The compression fatigue test involves compressing a breast implant between a fixed and a mobile plate, the implant being repeatedly compressed for 2 million cycles at 200 cycles per minute.

The impact resistance test involves dropping a specified mass vertically onto the breast implant, the height of the drop being dependent upon the mass of the implant.

Shell integrity testing
The breast implant shell material is tensile tested; the sample must elongate to 450% of its original length.

The joint integrity is tested by cutting a sample across the filling patch and subjecting this to tensile tests. The sample must elongate to 300% of its original length.

The tear resistance of the elastomer must be determined using a standard tear test.

Other testing requirements
The valve competence of a fillable breast implant is tested by filling the implant to a specified pressure and inspecting it for leaks.

The injection site must not leak following the defined number of punctures with the filling needle recommended by the manufacturer.

The surface characteristics of the breast implant need to be defined and must be evaluated over a representative portion of the surface.

The extent of gel bleed must be measured; there is as yet no standardised method by which to determine gel bleed.

The cohesiveness of the silicone gel must be measured; it must remain in one piece and not flow more than a specified amount over a given time using the equipment defined.

European Commission Guidelines
In all countries of the European Economic Area, with the exception of France, demonstration of conformity with the Essential Requirements of the Medical Devices Directive is accepted as an adequate basis for the marketing of silicone gel breast implants.

In May 1996, the French Ministry of Health issued a decree requiring silicone gel breast implants to be tested prior to being placed on the market to confirm conformity with health and safety requirements. The Ministry considered breast implants to be particularly at risk of rupture and were concerned that subsequent diffusion of the filling might lead to serious secondary effects in implanted women.

The European Commission, in seeking to achieve uniform implementation of the Medical Devices Directive across Europe, requested that a Project Group be set up to develop guidance for the conformity assessment of breast implants according to the relevant annexes of the Medical Devices Directive. This Project Group reported back to the Commission, in 1997, with the requested guidelines. These contained the technical specifications the Group considered necessary as a pre-requisite to CE-marking of breast implants, to denote that they conform with Essential Requirements for safety and performance contained in the European Medical Devices Directive.

A report commissioned by the French Ministry of Health to establish technical recommendations for marketing in relation to the provisions of the Medical Devices Directive was also submitted to the European Commission in 1997. The European Commission appended this report to the guidelines developed by the Project Group and intends to publish the resulting document to form a basis for reaching a common European position on what measures are adequate to ensure the safety and performance of breast implants.