FTIR MICROSPECTROSCOPIC ANALYSIS OF NORMAL HUMAN CORTICAL AND TRABECULAR BONE

Fourier transform infrared microspectroscopy (FTIRM) has been used to study the changes in mineral and matrix content and composition in rep licate biopsies of nonosteoporotic human cortical and trabecular bone. Changes in osteonal bone in these same samples were reported previous ly. Spectral maps along and across the lamellae were obtained from ili ac crest biopsies of two necropsy cases. Mineral:matrix ratios, calcul ated from the integrated areas of the phosphate nu(1), nu(3) band at 9 00-1200 cm(-1) and the amide I band at approximate to 1585-1725 cm(-1) , respectively, were relatively constant in both directions of analysi s, i.e., along and across the lamellae. Analysis of the components of the nu(1), nu(3) phosphate band with a combination of second-derivativ e spectroscopy and curve fitting revealed the presence of 11 major und erlying moieties. Of these, the ratio of the relative areas of the two underlying bands at approximate to 1020 and approximate to 1030 cm(-1 ) has been shown to be a sensitive index of variation in crystal perfe ction in both human osteonal bone and in synthetic, poorly crystalline apatites. This ratio was calculated in both cortical and trabecular b one from human iliac crest biopsies along and across the lamellae. The ratio decreased, going from the periosteum to the medullary cavity in the cortical bone, and from the periphery towards the center of trabe culae. These observations were consistent within serial sections obtai ned from the same biopsy, multiple biopsies obtained from the same nec ropsy specimen, and biopsies obtained from the two different necropsy specimens. The results presented here along with previously reported c hanges in osteonal bone show a relation between bone age and ''crystal linity/maturity'' (a parameter dependent on crystallite size, hydroxya patite-like stoichiometry, abundance of substituting ions such as CO32 - the more crystalline/mature, the more hydroxyapatite-like stoichiome try, the bigger the crystallite size, the less the ion substitution by ions such as CO32-) as deduced by the 1020/1030 cm(-1) ratio. Invaria bly, younger normal bone is less mature/ crystalline than older. These results provide a ''baseline'' for description of mineral properties, to which diseased bones may be compared.