Fluid flow in stressed bone is not well characterized. This fluid flow is important because of the probable role that it plays in remodeling of bone. The fluid could affect remodeling either by creating direct pressure on the cells, or by causing streaming potentials as it flows. The purpose of this work is to experimentally determine the permeability of bone to fluid, and to investigate the effect of fluids on the mechanical damping of bone and the relaxation time of the fluid pressure in stressed bone.
The permeability was determined for bovine bone, in vitro. The results indicate that the permeability of bone is sensitive to sample preparation. The value of the permeability for thin samples (< 3mm) depends on the microstructure of the samples. Longitudinal Haversian samples have permeabilities in the range 1-50 x 10-14 m², while tangential samples, and longitudinal plexiform samples are in the range of 1-15 x 10-14 m². Thin radial samples are in the range 0.8-4.4 x 10-14 m².
The permeability for thick samples (3mm<t<5mm) appears to be isotropic. Each thick sample tested in this experiment had a permeability in the range 0.9-5.2 x 10-14 m², regardless of the sample's microstructure or orientation.
The mechanical damping (Tan Delta) was measured for bovine bone with glycerol solutions in the pores. There is a substantial increase in the damping with percent glycerol, from .01 for distilled water to .03 fo r 100 percent glycerol. Similar results were obtained using ethylene glycol, but polyethylene glycol 1500, and sucrose do not cause any significant increases in the damping. Possible reasons for these differences are put fo rth .