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Biorheology, 40 (2003) 1-3 pp 347-353
IOS Press
COMPARATIVE ANALYSIS OF DIFFUSIVE AND STRESS INDUCED NUTRIENT
TRANSPORT EFFICIENCY IN THE LACUNAR-CANALICULAR SYSTEM OF
OSTEONS
Nikola Petrov and Solomon R. Pollack*
Institute of Mechanics and Biomechanics, 1113 Sofia, Bulgaria, petrov333@gmail.com
*Department of Bioengineering, University of Pennsylvania, PA19104-6392, USA,
spollack@seas.upenn.edu
Abstract. Marker migration experiments suggest that cyclic mechanical loading of cortical bone
in vivo increases marker penetration into bone. Is this a result of stress induced fluid flow or of
stress stimulation of active transport processes? Active lacunar-canalicular transport of nutrients
was suggested by Ham in 1979 on the basis of the presence of actin filaments in osteocyte
processes and their suspected role in cell motility. In addition, Tanaka in 1984 observed active
transport of microperoxidase in bone and Tanaka-Kamioka et al., in 1998 observed
experimentally that osteocyte processes are able to actively change their form.
In this study we performed parametric and comparative analyses of the transport efficiencies of
diffusion and stress generated fluid flow of (glucose) nutrients in lacunar-canalicular systems in
cortical bone. The result obtained is that neither diffusion nor stress induced fluid flow is capable
of sustaining osteocyte viability. It is possible that cyclic stress stimulates an active nutrient
transport mechanism to supplement stress flows.
1. Introduction
Osteocytes in cortical bone are located within lacunar-canalicular spaces. These spaces
interconnect permitting gap junction communication between neighboring osteocytes. In
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addition, the lacunar-canalicular volume is larger than the osteocyte so that a porous fluid filled
region surrounds the cells and their processes. It is important to note, however, that the volume
of the fluid surrounding the osteocyte is smaller than (or equal to) the volume of the osteocyte
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