[Physiopathology of osteoporosis]

The pathophysiology of osteoporosis has seen many recent progress especially with the use of genetically modified animal models.

Among many discoveries, one can notice the crucial role of LRP5, GH, IGF-1 and the sex hormones receptors in the acquisition of the peak bone mass, the control of bone remodeling by the sympathetic nervous system and his implication as a transmitter of mechanical loading in bone. Also, the role of estrogen and androgen receptors as well as the aromatase is specified according to sexes. The role of growth plate's chondrocytes in the installation of the trabecular bone network is better and better demonstrated. The greater periosteal apposition in men, mediated by androgens receptor, seems to explain the greatest radial growth and so the greatest bone resistance to mechanical strains like a lower fracture rate in men compared to women. The bone microarchitecture and quality explain an important part of the mechanical properties of bones and why considering the same bone mass one bone is breaking and another one not.

Many therapeutic applications should finalize the discovery of these new bone cells signalisation pathways.