Brennan, MA, Gleeson, JP, O'Brien, FJ and McNamara, LM (2014) Effects of Ageing, Prolonged Estrogen Deficiency and Zoledronate on Bone Tissue Mineral Distribution. Journal of the Mechanical Behavior of Biomedical Materials, 29. pp. 161-170.

Abstract

The quantity and distribution of bone tissue mineral are key determinants of bone strength. Conflicting findings regarding changes in bone mineral content and distribution during the disease of osteoporosis have been reported. Rapid increases in bone remodelling occur at the onset of estrogen deficiency but this response abates over time and as such altered tissue mineralisation might be a transient characteristic of osteoporosis. Bisphosphonate drug treatments reduce fracture incidence by 50-60%, but increases in bone mass alone are insufficient to bring about such changes. Since bisphosphonates alter bone remodelling, the distribution of bone tissue mineral might also be altered. In this study we test the hypothesis that bone tissue mineralization is altered over prolonged estrogen depletion and bisphosphonate treatment. Quantitative backscattered imaging (qBEI) was used to quantify bone mineral density distribution (BMDD) parameters (mean, median, peak, FWHM) from trabeculae of the proximal femora of an ovariectomized ovine model that underwent estrogen deficiency for 31 months, an ovariectomized group administered with Zoledronic acid and aged-matched controls. To assess the effects of normal ageing and prolonged estrogen deficiency, data were compared to BMDD data from sheep that were estrogen deficient for 12 months and age-matched controls. We report that normal ageing increases mean mineralization and mineral heterogeneity at a trabecular level. In contrast, prolonged estrogen deficiency leads to significantly decreased mean mineralization and further exacerbates increases in mineral heterogeneity. Interestingly, ZOL treatment of OVX sheep significantly reduced tissue mineral variability, both at a trabecular level and between femoral regions. Together, these findings indicate that ZOL treatment acts to reverse the increased heterogeneity occurring during estrogen deficiency and restore mineralization levels closer to control values.

Item Type:	Article
Keywords:	Mineralization, BMDD, osteoporosis, Zoledronic Acid, heterogeneity
Date Deposited:	02 May 2016 23:45
Last Modified:	02 May 2016 23:45
URI:	https://oak.novartis.com/id/eprint/6804