In its simplest form, a remodeling cycle consists of four phases: activation, resorption, formation, and resting. Bone remodeling is activated by systemic hormonal changes, localized mechanical damage, or aging . These factors trigger osteocytes to secrete signals that stimulate the proliferation of mononuclear cells, which fuse into preosteoclasts and then become active osteoclasts . As osteoclasts resorb bone, signaling factors (e.g., transforming growth factor beta (TGF-β), insulin-like growth factor (IGF)-1, IGF-2, bone morphogenic protein (BMP)2, and Wnt-10b ) are released from the bone matrix or secreted by osteoclasts themselves. These signals, in turn, initiate osteoblast proliferation, migration, and activation. Osteoblasts produce the extracellular protein matrix that becomes bone tissue. Osteoblasts either become osteocytes during bone formation or undergo apoptosis afterward.