Osteoporosis, often considered a national epidemic, and other bone deficiencies are costly in human and monetary terms. Severe osteoporosis strikes 15 percent of women and 8 percent of men during their lifetimes, causing painful fractures and deformities that dramatically decrease the quality of life. More than 500,000 patients nationwide need bone grafts each year to treat fractures, to achieve effective spinal fusions or to heal disabling skeletal defects. For half of these patients, bone must be “harvested” from their pelvis to serve as a graft, which may result in additional scarring, blood loss, and chronic pain