This research will investigate 72 postmenopausal women with normal or osteopenic BMD by dual-energy x-ray absorptiometry (DXA), 36 with prior low-trauma fractures will be compared with 36 age-, race- and BMD matched women without fracture. We hypothesize that 1.) Women with fractures will have evidence of microarchitectural deterioration on HR-MRI and 2.) Newly developed, more rapid MRI sequences designed at the UW will provide similar trabecular microstructure information more rapidly than the currently used, albeit investigational, technology produced by MicroMRI, Inc.