[Contribution of osteo-densitometry in the definition and diagnosis of osteoporosis].

Since its first characterisation, osteoporosis has always been defined on an anatomical basis. The term osteoporosis refers to a reduction (or atrophy) in the amount of bone tissue and to microarchitectural deterioration without any mineralisation defect. Its clinical significance lies in the fractures (vertebral fracture, Colles' fracture and hip fracture) that occur spontaneously or after a minimal trauma. During the past 15 years, developments in technology of bone mass measurement (osteodensitometry) currently allow a diagnosis of osteoporosis at its anatomical stage characterised by a reduction in bone mass (osteopenia) without any symptom. A definition based on densitometry offers the major advantage of an early diagnosis, well before the development of fractures. It has been validated recently by several prospective studies which have confirmed the close relationship between the decrease in bone mass and the fracture risk. This modern densitometric approach of osteoporosis has major therapeutic implications. Indications of curative treatments of osteoporosis has major therapeutic implications. Indications of curative treatments of osteoporosis should be reconsidered according to the contribution of bone densitometry.