Functional strain as a determinant for bone remodeling.

Mechanical function has always been acknowledged to have a significant, continuing but hitherto unquantified influence on bone remodeling. The structural objective of this relationship is presumably to ensure that, at each location throughout the skeleton, there is sufficient bone tissue, appropriately placed, to withstand functional load-bearing without damage. The architectural modifications necessary to achieve and maintain this structural competence are made by the coordinated remodeling activity of populations of osteoblasts and osteoclasts. The specific structure-function objectives at each location remain undefined, as are the mechanisms by which tissue loading is transduced into cellular control. The remodeling responses following a variety of experimental alterations in bones' strain environment are presented. Their significance to the process of remodeling control is discussed, and a scheme for the interaction of mechanical and hormonal influences proposed.