Fig. 1

Bone remodelling cycle and bone degeneration in osteoporosis. The dynamic relationship between osteoblasts and osteoclasts is primarily regulated by a fine balance between bone formation and bone resorption. a In healthy bone tissue, resorption of bone following the resting phase is mediated by osteoclasts and counter-balanced by deposition of new bone material by osteoblasts. Once new bone material has been deposited, another resting phase follows. b With increasing age and in patients with osteoporosis, the balance shifts towards higher levels of osteoclast activation with reduced osteoblast differentiation, thereby impairing the regenerative potential of the bone and resulting in structural deterioration of the bone tissue along with reduced bone strength