[Effects of aging and therapy on the structural properties and strength of vertebral body].

Bone strength depends on its structure and its material properties. Structural properties are determined by the size and shape of bone and also the microarchitecture. Material properties are determined by mineral crystallinity, collagen structure and microdamage in bone. The strength of bone is adapted to the needs of physical activities by biologic mechanisms, bone modeling and remodeling. The deterioration of bone strength in postmenopausal women is characterized by a trabecular bone deficit with poor trabecular connectivity and followed by a cortical bone deficit with trabeculation of endocortical bone and intracortical porosity due to accelerated bone remodeling. Trabecular bone is getting more fragile with age by poor adaptation to mechanical load by modeling. As a consequence, the endplate collapses and vertebral body fracture occurs. The deterioration of bone strength could be improved by osteoporosis treatment using antiresorber or teriparatide, and these drugs would decrease the risk of vertebral fracture consequently.