BONE MASS HOMEOSTASIS AND BISPHOSPHONATE ACTION

The evidence supporting the concept of bone mass homeostasis controlle d by mechanical loads is summarized, The web-known adaptation of bone structure to mechanical loads can only be achieved if an increase in l oad stimulates bone formation and a decrease stimulates bone resorptio n, This defines the feedback system that can play a role in the coupli ng of bone formation to bone resorption, The two processes are not det ermining bone mass, but serve as means to maintain it at the homeostat ic level, Imbalance produced by excess resorption, which cannot be eff ectively matched by increased formation, a slower process, causes bone loss. Slowing of bone resorption can facilitate the restoration of bo ne mass to homeostatic levels and, since bone formation is mechanicall y driven, the newly evolving structure would best be suited for mechan ical usage and should reduce the risk of fractures (C) 1997 by Elsevie r Science Inc.