Aneurysm clips made of plastic materials

Research project "MR-Clip" - plastics technology for an improved aneurysm therapy

In the "MR-Clip" research project, M.TEC and four project partners are driving forward the idea of producing a so-called aneurysm clip for the treatment of aneurysms in the human body from fiber composite plastic. Until now, aneurysm clips have been made of metal, which makes follow-up examinations with magnetic resonance imaging (MRI) difficult due to distorted optical images. A clip made of polymer materials would eliminate this problem - a revolutionary step in this medical technology field.
Aneurysms are among the most dangerous types of vascularisation in the human body. These local, mostly vesicular dilatations occur in brain vessels in about two percent of those affected. There they can cause cerebral haemorrhages, which in the worst case can lead to death. There are two approaches to treating such aneurysms: "coiling" and "clipping". In the clipping method, the aneurysm is disconnected from the bloodstream with a clip. The safety of a complete seal is very high and the aneurysm is no longer considered dangerous.

Complicated aftercare - metal implants distort MRT images

Theoretically, the follow-up examinations could easily be carried out using magnetic resonance imaging (MRI) - if it were not for the metal material, which causes dark shadows due to its material properties during optical imaging in MRI devices. These so-called artifacts prevent a reliable evaluation. The patient must therefore be examined by catheter every six months. These interventions are costly and involve health risks. 
Up to now, metals have been used for aneurysm clips because they have been tested as a material and have good biocompatibility. Another point is that the spring element within the aneurysm clip must build up a high force - as a very small component. This force/size ratio can be better implemented with metallic materials.

A medical technology revolution made of plastic

Some polymeric materials cause significantly fewer artifacts in MRI images. These polymeric materials offer the prospect of simplifying the aftercare in aneurysm therapy and making it more cost-effective.
However, if fiber composite plastic with a thermoplastic matrix is used instead of metal, it is more difficult to build up sufficient clamping and tensioning force in the clip's clamp to achieve the necessary closing pressure. Plastic materials are simply less rigid than metals. Added to this is the necessary deformation of the fiber composite profile. This is not a problem with the widely used thermoplastics. With plastics that are fiber-reinforced, however, such a process step does not have to be knocked down to the last detail. In addition, there are possible tolerance fluctuations of the preformed fiber composite profile, which can have a negative impact on large series production.

However, these challenges are counterbalanced by the great advantages of the plastic manufacturing processes. Plastics offer a high degree of functional integration. Fasteners, for example, are integrated into the components in a single step, which can simplify the manufacturing process. And reworking of the individual parts is reduced. This makes production more cost-effective.

The "MR-Clip" research project and the partners involved

In this research project, M.TEC and the project partners are developing concepts for a plastic aneurysm clip and the associated application tools. The Fraunhofer Institute for Product Technology IPT is in charge of the material development of the fiber composite plastic to be used. The tools and devices required for the production of the plastic clips are developed by the company Werner Grathwohl. In order to examine the quality and usability of the prototypes, the Clinic for Neurosurgery at Saarland University will test the new clip in trials and MRI. Peter Lazic GmbH has been commissioned to contribute to the development of the new plastic prototype as project coordinator, using its expertise in metal clips.

The engineers of M.TEC are responsible for the development and construction of the plastic clip. Constructing alternatives for metallic superstructures made of fiber composite structures is one of the regular tasks of the M.TEC engineers. Their experience and know-how as an interdisciplinary product developer help to successfully complete the "MR-Clip" project and to create the basis for later series production.

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Stefan Vogler
Stefan Vogler
Team manager simulation & calculation
+49 2407 9573-7321
+49 2407 9573-25
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