A histomorphometric observation of flows in cortical bone under dynamic loading

Ferritin was used as a histological marker for interstitial fluid flows in four goats. Two transcortical pins were inserted into each tibia mediolater ally-one at the proximal side and one at the distal side of the diaphysis. For the experimental limb, dynamic loading was applied to the pins on the l ateral side. The contralateral limb was used as control. Ferritin was injec ted into the nutrient arteries feeding the two tibiae. The goat was then eu thanized immediately. Undecalcified slides of the tibial cortical bone from both the experimental and the control limbs were studied histologically. P ercentages of Haversian systems marked with ferritin halos and the average radial distance of ferritin transudation away from the Haversian canals wer e assessed. Results for the medial and lateral sides of both the experiment al and control tibiae were reported. Significant differences in the ferriti n transudation distance were found between the experimental and the control tibia (P < 0.005) and between the medial and the lateral sectors (P < 0.05 ). The approach documented in this paper could be used to address systemati cally how external loading might affect the transport phenomena in cortical bone. (C) 2000 Academic Press.