Strain amplification in the bone mechanosensory system

In this work we suggest a mechanism whereby the low magnitude of the strain applied to the whole bone (0.1% to 0.3%) can be amplified by nearly two orders of magnitude at the membrane of the cell process. A mechanical loading range from 1 MPa to 20 MPa at different frequencies, 1 Hz to 20 Hz, was considered. We calculated the ratio of the drag force on the fibers to the shear force on the osteocyte membrane in a canaliculus and found that the drag force is at least 50 times larger than the shear on the cell membrane. We also calculated the strain at the membrane, as well as the strain amplification ratio, and found that the strain amplification ratio can reach as high as 65 for this loading range. Thus the proposed mechanism amplifies the strain applied to the whole bone when it is experienced at the osteocyte process membrane