Radiation therapy is a common clinical technique used to reduce tumor proliferation. A 2005 study by Baxter et al. showed that women who received pelvic radiation therapy were more likely to experience a pelvic fracture and 90% of these fractures were hip fractures [3]. There is also clinical evidence that premenopausal women with gynecological tumors may experience a premature and permanent menopause as a result of damage to the ovaries caused by radiation therapy [11]. The effects of this early onset estrogen deficiency on bone health may be more severe since these patients likely have not reached peak bone mass.

Both structural and material properties play an important role in the assessment of bone strength and fracture risk. Structural parameters, such as bone volume and trabecular thickness, are often studied more frequently due to the relative ease of access to imaging modalities and the ability to image in vivo. Changes in bone composition and material properties resulting from disease states or treatment methods are just as important in predicting bone function, but are more difficult to assess. In the first aim, a mouse model for structural changes resulting from fractionated radiation therapy and estrogen deficiency will be characterized at multiple skeletal sites. In the second aim, the efficacy of zoledronate to mitigate bone loss from radiation therapy will be evaluated by examining structural and material properties at three time points in a mouse model. For the final aim, the techniques developed in aim two will be applied to evaluate joint changes following hemarthrosis in a mouse model.