Bone is remodelled by a specific sequence of cellular events which always begins with osteoclastic bone resorption, followed by new bone formation (Fig. 18.5). This occurs both within the haversian systems and on trabecular bone surfaces. The cellular events are always the same, commencing with osteoclastic resorption and concluding with new bone formation. The bone that is removed by the activity of the osteoclasts is precisely replaced in normal health by the activity of osteoblasts. Thus, there is a balance in normal health between the processes of bone resorption and bone formation .
