Bioactive Surface Modifications through Thermally Sprayed Hydroxyapatite Composite Coatings: A Review over Selective Reinforcements

Hydroxyapatite (HA) has been an excellent replacement for the natural bone in orthopedic applications, owing to its close resemblance; however, it is brittle and has low strength. Surface modification techniques...

Investigation of degraded bone substitutes made of magnesium alloy using scanning electron microscope and nanoindentation

Degradable bone substitutes made of magnesium alloys are an alternative to biological bone grafts. The main advantage is that they can be manufactured location- and patient-specific. To develop and scale appropriate implants using computational models, knowledge about the mechanical properties and especially the change in the properties during the degradation process is essential. Therefore, degraded open-pored implants were investigated using scanning electron microscope and nanoindentation to find their material composition and mechanical properties. Using both techniques the correlation of the material composition and the average modulus was determined. It could be shown that the average modulus of the degradation layer is distinctly lower than that of the base material. The local average modulus of degrading implant highly depends on the magnesium concentration and the accumulation of elements from the environment. A decrease in magnesium concentration leads to a decrease in the average modulus. Thus, the degrading implant had a lower stiffness than the initial structure.