Iron Based Degradable Foam Structures for Potential Orthopedic Applications

Abstract

Iron and iron based alloys have been identified as appropriate biodegradable osteosynthesis material with the ability of bearing high loads for the temporary replacement of bones. They combine high strength at medium corrosion rates. Open cell iron based foams have been manufactured by replication method on the basis of the highly uniform structure of foamed polyurethane by powder metallurgical approach. Bare carbonyl iron samples and samples with addition of carbon nanotubes (CNTs) and magnesium have been tested with respect to their microstructure, their degradation rate, and their cytotoxicity. The electrochemical corrosion behaviour has been studied in Hank’s solution and physiological saline solution. Potentiodynamic polarization experiments conducted at 37°C indicated the increased biodegradation rates resulted from porous structure of foam samples. Corrosion rates determined by the Tafel extrapolation method were in the sequence: Fe-Mg, Fe, Fe-CNTs from higher to lower. The cytotoxicity test showed small proliferation of osteoblastic cells incubated on iron based samples.