Mechanotransduction in bone: the role of strain rate.
Turner, Charles H., Ichiro Owan, and Yuichi Takano.
Department of Orthopaedic Surgery, Department of Mechanical
Engineering, Department of Anatomy, and The Biomechanics and
Biomaterials Research Center, Indiana University Medical Center,
IUPUI, Indianapolis, IN 46202, USA
APStracts 2:0074E, 1995.
Bone tissue can detect and respond to its mechanical environment, but
there is no consensus for how bone cells detect mechanical loads.
Some think that cells sense tissue deformation (strain) and respond
when strain is abnormally high. However, strains in bone tissue are
usually very small and it is questionable whether bone cells are
sensitive enough to detect them. Another theory suggests that
mechanical loads are coupled to the bone cells by stress-generated
fluid flow within the bone tissue which is dependent upon the rate of
change of bone strain. We applied bending loads to the tibiae of
adult rats that created equivalent peak strains in the bone tissue
but with varied rates of strain. Bone formation was significantly
increased in the two experimental groups with the highest strain
rates compared to the groups with lower strain rates (p<0.01) and
the amount of new bone formation was directly proportional to the
rate of strain in the bone tissue. These results suggest that
relatively large strains alone are not sufficient to activate bone
cells. High strain rates and, possibly, stress-generated fluid flow
are required to stimulate new bone formation.
Received 9 January 1995; accepted in final form 7 April 1995.
APS Manuscript Number E5-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.