The microvasculature in the cortex and marrow of the adult canine tibial
diaphysis was filled with the silicone elastomer Microfil, the bone was
decalcified, and the water was replaced with methylsalicylate to permit
three-dimensional visualization of the microvascular arrangements. The
tibial nutrient artery was seen to supply the marrow and the cortex via
parallel, independent sets of arterioles and terminal capillary beds. No
arteriolar or capillary anastomoses were observed linking these separate
beds. The major portion of the venous drainage was found to be via small
venules through the cortex into periosteal veins. Many small venules
draining the medullary capillaries penetrated the cortex, and there were a
few larger emissary veins, including the nutrient vein. Because the marrow
and cortex have separate capillary beds in parallel, microsphere deposition
should be appropriate for estimating the regional blood flows. CLINICAL
RELEVANCE: The results of this study should be of concern to surgeons who
perform whole diaphyseal bone replacements, as the effluent venous vessels
are important in re-establishing the circulation by microsurgical
methods.