http://www.surgeongeneral.gov/library/bonehealth/factsheet1.html
Office of the Surgeon General, U.S. Department of Health and Human Services
Bone diseases are conditions that result in the impairment of normal bone function and can make bones weak. This fact sheet contains general information about bone diseases, including why healthy bones are important, who is at risk, how to prevent osteoporosis, and how to prevent falls.