THE ANALYSIS OF BIOMEDICAL HYDROXYAPATITE POWDERS AND HYDROXYAPATITE COATINGS ON METALLIC MEDICAL IMPLANTS BY NEAR-IR FOURIER-TRANSFORM RAMAN-SPECTROSCOPY

In this paper we discuss the application of Fourier transform Raman (F M) spectroscopy to the in situ analysis of the inorganic bioceramic hy droxyapatite in both powder form and as a thermally sprayed hydroxyapa tite coating on metals currently employed in medical implants for orth opaedic surgery. The derivation of the FTR spectrum of hydroxyapatite is attempted by the analysis of the pure powders of its known constitu ents. The FTR spectra of hydroxyapatite powders sintered up to 1300-de grees-C suggest significant structural changes in the region of 1250-d egrees-C. The FTR spectra of coated metal systems clearly distinguish between samples of differing crystallinity and provide some informatio n on the effect of the coating process on the hydroxyapatite material. The preliminary examination of hydroxyapatite coated dental screws sh ows a change in the nature of the hydroxyapatite coating on recovery a fter clinical use.