[Changing concept and definition of osteoporosis]

History of osteoporosis dates back to prehistoric era and no real progress in the understanding of osteoporosis was made until 1900 AC when Roentgen discovered X-ray to make bone visible in vivo. From this time to 1950 when Albright and many others opened way to the pathophysiology of osteoporosis as one of the metabolic bone diseases, X-ray picture was the only tool to assess osteoporosis. Subsequent biochemical, epidemiological and endocrinological approach clarified the risk factors and pathophysiology of osteoporosis in the modern age. Treatment and prevention of osteoporosis also became feasible based on these development. Such a rapid progress in the understanding of osteoporosis also caused an inevitable confusion in the concept of osteoporosis.