Open cellular magnesium alloys for biodegradable orthopaedic implants

Replication processing using NaCl spaceholders offers the possibility to produce cellular structures for a range of Mg alloys. Four Mg alloys (AZ63, M2, ZM21 and MZX211) were processed into open cellular structures with a pore size near 500 μm and a porosity of 75% using an optimized NaCl leaching procedure. The production method was found to be robust and yielded samples of acceptable strength and stiffness. Their dissolution rate (by H2 release in simulated body fluid) and mechanical properties (by cyclic compression) were measured. For all 4 alloys the initial mechanical properties mimic those of cancellous bone; however, the dissolution rate is too high for direct use in the human body, leading to excessive hydrogen evolution and overly rapid degradation of mechanical properties. Further post-processing of the material is thus required.