Small Pores, Great Effect
 

Researchers at Leibniz Universität Hannover develop magnesium sponges to improve healing in broken bones

Scientists at the Production Technology Centre in Hannover are working on the topic ‘Magnesium sponges as bio-resorbable implants’ as part of special research area 599. These implants have open pores like a sponge, are as light as a feather and as resilient as human bone. This material’s structure ensures the fast accumulation of bone. The material dissolves automatically in the body during the healing process of the bone defect and leaves no residue.

According to hospital diagnosis statistics more than 700,000 fractures were treated at German hospitals in 2006, including 50,000 broken wrists and ankles. These are often complex injuries that necessitate the use of steel or titanium implants. If these metal compounds remain in the body for a long period they can lead to infections. Follow-up operations are then essential to remove the pin or screw once the fracture is healed.

“We aim to simulate the human body very closely in our magnesium sponges“, explains Dr. Dirk Bormann, Head of Biomedical Engineering and Lightweight Design at the Institute of Materials Science at Leibniz Universität Hannover. He is holding a two-centimetre magnesium pin in his hand, as thin as a pretzel stick. Tiny holes are visible on its surface. This kind of magnesium sponge with a porous structure is created when a substitute material such as sodium chloride granules is infiltrated with magnesium and the substitute material is then washed out. The piece of magnesium sponge may have the diameter of a pretzel stick but it is not nearly as fragile. “Metallic foams and sponges correspond to the natural structure of bone material and display good mechanical strength“, says Dr. Bormann. This has been proven in comprehensive crush and strain tests. The corrosion characteristics of magnesium are decisive for its application in the medical sector. In addition magnesium alloys do not cause allergic reactions in the body when correctly selected.

The mechanical engineers produce models of the magnesium sponges in order to then test them in cooperation with their research partners at the Helmholtz Centre for Infection Research, University of Veterinary Medicine Hannover and Hannover Medical School. The interaction of magnesium and organic cells is characterised in molecular biology in cell cultures and histologically on animal models in order to draw consequences for reactions in the human body and to define future areas of application.

Another step towards the application of magnesium sponges in medical technology is being taken with a project that will begin in the spring of 2009. The Institute of Materials Science is working with researchers in Aachen, the Orthopaedic Clinic and the Polyclinic at Hannover Medical School and two other companies to develop a procedure in which the pores of the sponge can be filled with a polymer that stores medication. This will further improve the stability and tolerability of the implants.

Meldung vom 21.01.2009