Characterization of the interface between hydroxyapatite coating film and bone: use of a new expression to correct matrix effects for PIXE measurements in thick samples embedded in resin

Development of biomaterials for use as bone substitute requires better control of the process of materials degradation and bone substitution. At present, composite implants of alloy coated with bioceramic are being developed. In this paper, a cylinder made of TiAl6V4 alloy coated with hydroxyapatite is used to simulate a hip prosthesis integration. Physico-chemical evaluations are needed to determine such an implant osseointegration process. Use of the particle induced x-ray emission (PIXE) method with histological sections results in quantitative cartography of elements at the bone-implant interface. The sensitivity of the PIXE method in measuring low concentrations of elements gives information to better understand bioresorption of calcium phosphate ceramics and events occurring at this dynamic interface. However, concentration evolution in different elements is still going on and reflects the ceramic resorption. In our case, the alpha parameter method based on experimental determination of the correction of matrix effects is useful as it allows data corrections to be calculated without hypotheses about matrix composition. In the present paper, we propose an expression to calculate directly the correction factor and an application to the characterization of the interface between hydroxyapatite coating film and bone.