Fig 1. Bone remodeling sequence. A cartoon depiction of the sequential action of osteoclasts and osteoblasts to remove old bone and replace it with new bone. For simplicity of illustration, the cartoon shows remodeling in only 2 dimensions, whereas in vivo, it occurs in 3 dimensions, with osteoclasts continuing to enlarge the cavity at one end and osteoblasts beginning to fill it in at the other end. Reproduced with permission of the American Society for Bone and Mineral Research from J Bone Miner Res (2005;20:177–84).