[The concept of severe osteoporosis].

In diagnostic criteria of primary osteoporosis in Japan, there is no expression of severe osteoporosis. In the primary osteoporosis, the criteria of WHO is difficult to use in our daily medical care. In 1992, we opened "The osteoporosis dock" in the department of osteopaedics of National Nishisaitama Chuo Hospital. From experience of our osteoporosis dock, we tried to answer the question with "what is the concept of severe osteoporosis?".