Spatially resolved elemental distributions in articular cartilage

In this study, the nuclear microprobe technique is employed to analyse the chemistry of joint cartilage in order to correlate internal structures of t he collagen network with the elemental distribution. The samples were taken from pig's knee joint. 30 mum thick coronar cross-sections were prepared b y means of cryosectioning and freeze-drying. We performed simultaneously pa rticle induced X-ray emission (PIXE), Rutherford backscattering spectrometr y (RBS) and elastic recoil detection analysis (ERDA). Thus we obtained spat ially resolved distributions of the elements H, C, N, 0, P, S, Cl, K and Ca . The main components of the organic matrix are H, C, N and O. It was shown that their relations vary with the cartilage structures. It could be shown that zones with aligned collagen fibrils contain less sulphur and potassiu m but more chlorine. The higher chlorine concentration is remarkable becaus e newest biochemical studies found that hypochloric acid is involved in car tilage degradation. Furthermore, the calcium distribution is still of great interest. Its correlation to structural changes inside the cartilage is st ill being discussed. It could be disproved that zones of higher calcium con centration are related to the aligned structures of the collagen network. ( C) 2001 Elsevier Science BN. All rights reserved.