Morphological and Mechanical Changes in Ovariectomized Rat Tibia with Treatments of Ibandronate and Parathyroid Hormone

Yang, Xiao; Chan, Yong Hoow; Muthukumaran, Padmalosini; Lee, Taeyong

Abstract

Osteoporosis is a debilitating disease affecting the elderly population, associated with compromised stability and reduced mobility of the bone. Osteoporosis is diagnosed as a condition when the measured bone mineral density (BMD) falls below 2.5 standard deviations of peak mass. However, BMD alone might not be enough to define the osteoporotic condition because it does not accounts on the micro-architectural changes in the bone trabeculae. Thus, this study aimed at studying the micro-architecural changes in trabeculae rich bone metaphysis of ovariectomized rat models in comparison with the conventional BMD measurements and the mechanical parameters. In this study, proximal tibiae of twenty-five female rats from four different groups (SHAM, OVX, IBAN and PTH) were evaluated using micro-CT, pQCT and three point bending tests. The micro-CT analysis showed that the deterioration of trabecular bone was significant during the first 6 weeks after OVX surgery. During the early stage of osteoporosis, the trabecular density decreased more rapidly than the cortical density. Morphological analysis showed that early administration of both ibandronate and parathyroid hormone has a beneficial effect on restoring the trabecular structures. Bone mechanical properties of treatment groups did not show significant difference, but followed the overall trend as morphological indices. The results suggest that early administration of either ibandronate or PTH is effective in restoring the trabecular bone loss caused by osteoporosis. However, larger-scale studies should be conducted to better understand the effect of both anti-resorptive and anabolic treatments in terms of morphological and mechanical properties.