In vitro degradation of absorbable metals

The degradation behavior of absorbable metals in medical devices can be tested in vitro. The ASTM F3268 standard describes an experimental approach for testing absorbable metals and alloys such as magnesium, iron and zinc. Based on this standard, the test set-up and the test conditions for simulating a physiological environment were defined in the interlaboratory test for the ASTM work project WK73273.

We validated the test setup of the interlaboratory test using a reference material and another magnesium alloy. The test involves storing a metal cylinder for at least two weeks at 37 °C in a simulated body fluid in an incubator. A defined CO₂ atmosphere ensures that the pH value of the immersion solution remains within the physiological range.

The test is suitable for the selection of alloys prior to in vivo studies to determine an in vivo in vitro correlation factor (IVIVC factor), for the incoming goods inspection of material batches and for the early screening of prototypes in combination with mechanical tests. It can be supplemented by other chemical, physical and mechanical tests offered by the RMS Foundation.