Loss of bone mass, along with microar-chitectural deterioration of the skeleton, leads to enhancedbone fragility and increased fractures—the bone diseaseknown as osteoporosis (1).

The purpose of remodeling in theadult skeleton is not entirely clear, although in bones that areload bearing, remodeling most likely serves to repair fatiguedamage and to prevent excessive aging and its consequences.Hence, the most likely purpose of bone remodeling is toprevent accumulation of old bone. Remodeling, with positivebalance, does occur in the growing skeleton as well. Its pur-pose, quite different from those proposed for the adult skel-eton, is to expand the marrow cavity while increasing tra-becular thickness (12).