Fig. 1.

Mechanotransduction. Physical mechanical loads elicit a biological response through the process of mechanotransduction. For bone, this process can be broken down in the following steps: (1) Transmission of the bulk mechanical stimulus to the osteocyte, (2) Sensing of the mechanical stimulus by osteocytes and transduction into a chemical response, (3) Modulation of intracellular signaling, (4) Production of signaling molecules. The last step leads to an altered osteoclast and osteoblast recruitment and activity, and an alteration in bone mass and structure. Changes on each of these levels of mechanotransduction, for example, by affecting the cellular structures described in the figure, will potentially affect the efficacy of mechanical stimuli for modulating bone mass and structure, and thereby the ability of bone to withstand fracture. Governing all steps of the process of mechanotransduction is the genetic make-up of the osteocytes