Determination of the elemental distribution in human joint bones by SR micro XRF

Abstract

AbstractIn humans the toxic trace element lead (Pb) mainly accumulates in the skeletal tissue where it resides for a long period. Although Pb is known to play a role in bone and cartilage diseases, the distribution of Pb in these tissues is mostly unknown. Therefore synchrotron‐radiation‐induced micro x‐ray fluorescence analysis (SR µ‐XRF) in various geometries was used to determine the distributions of Pb, Ca, Zn and Sr at the cartilage‐bone interface in human femoral heads and patellae. SR µ‐XRF results were matched with backscattered electron (BE) images providing information on structural features of the tissue. Conventional SR µ‐XRF at HASYLAB beamline L showed that Pb mostly accumulates in a zone of some micrometers around the transition between non‐calcified and calcified cartilage. However, the relatively large sample thickness did not allow more precise conclusions. Exploiting the 3D capabilities of confocal SR µ‐XRF and SR microfluorescence tomography at ANKA Fluo‐Topo beamline and HASYLAB beamline L, the spatial resolution could be improved and a highly specific accumulation of Pb at the tidemark, the calcification front between non‐calcified and calcified cartilage, was detected. It was found that Pb and Zn accumulation coincide at the tidemark. Since the tidemark plays an important role in osteoarthritis, the results may strengthen other authors' conclusions that Pb is associated with this joint disease. Although offering less spatial resolution when compared to micro‐tomography, confocal SR µ‐XRF is best suited for such studies. It facilitates the comparison of element maps with other imaging techniques like BE imaging. Copyright © 2007 John Wiley & Sons, Ltd.