Determination of concentration gradients in bone tissue generated by a biologically degradable magnesium implant

Abstract

Rare earth element (REE) concentration gradients in bone were quantitatively investigated by LA-ICP-MS using different reference materials and ablation patterns. For line ablations a matrix effect was observed during calibration procedures. The maximum concentration of REE in bone around a biologically degradable magnesium alloy implant was ∼200 µg/g after six weeks of implantation compared to a background concentration of 3–4 µg/g. No further accumulation of degraded REE in bone tissue around the implant was detected after 12 weeks of implantation. PIXE measurements showed an aluminium accumulation in the corrosion zone of the implant. Furthermore, new bone formation was identified by a variable Ca/P-ratio. The Ca/P ratio of the hydroxyapatite as the main inorganic constituent of bone tissue was not reached 12 weeks after implantation, indicating that the replacement of the implant by newly formed bone is still in progress.