Eleftherios P Paschalis, Peter Fratzl, Sonja Gamsjaeger, Norbert Hassler, Wolfgang Brozek, Erik F Eriksen, Frank Rauch, Francis H Glorieux, Elizabeth Shane, David Dempster, Adi Cohen, Robert Recker, Klaus Klaushofer

Bone strength depends on the amount of bone, typically expressed as bone mineral density (BMD) determined by dual x-ray absorptiometry (DXA), and on bone quality. Bone quality is a multifactorial entity including bone structural and material compositional properties. The purpose of the present study was to examine whether bone material composition properties at actively bone forming trabecular surfaces in health are dependent on subject age, and to contrast them against postmenopausal osteoporosis patients. To achieve this, we analyzed by Raman microspectroscopy iliac crest biopsy samples from: healthy subjects aged 1.5-45.7 years, paired biopsy samples from females before and immediately after menopause aged 46.7-53.6 years, and biopsy samples from placebo-treated postmenopausal osteoporotic patients aged 66-84 years. The monitored parameters were: the mineral / matrix ratio; the mineral maturity / crystallinity (MMC); nanoporosity; the glycosaminoglycan (GAG) content; the lipid content; and the pyridinoline (Pyd) content. The results indicate that these bone quality parameters in healthy, actively forming trabecular bone surfaces are dependent on subject age at constant tissue age, suggesting that with advancing age the kinetics of maturation (either accumulation, or post-translational modifications, or both) change. For most parameters, the extrapolation of models fitted to the individual age dependence of bone in healthy individuals was in rough agreement with their values in postmenopausal osteoporotic patients, except MMC, lipid, and Pyd content. Amongst these 3, Pyd content showed the greatest deviation between healthy aging and disease, highlighting its potential to be used as a discriminating factor. This article is protected by copyright. All rights reserved.