Fluid spaces in normal and osteomyelitic canine bone

When cortical bone is afflicted by an infectious process, significant alterations in the physiology and anatomy occur at the cellular level. Included in these alterations are modulations of the various fluid spaces of cortical bone. Volume of distribution studies with 14C-labeled sucrose and 99Tc-labeled red blood cells in an animal model of acute, subacute, and chronic osteomyelitis of the tibia were performed to quantitate the various fluid spaces in cortical bone. Additionally, the studies were performed in cortical bone from the radius and tibiae (following sham operations) to allow comparison with normal and control values. The total exchangeable water, vascular, and interstitial fluid spaces were increased in all three types of osteomyelitic bone. With one-way analysis of variance and Duncan's multiple range test, the alterations observed in each type of osteomyelitic bone (acute, subacute, or chronic) were statistically different from those observed in normal bone (p = 0.001) and controls (p less than or equal to 0.01). The differences of the mean values observed among the three types of osteomyelitic bone were not statistically significant (p greater than 0.05). These pathophysiologic alterations in osteomyelitic bone must be considered when one studies the ability of various antimicrobials to reach bactericidal concentrations in the interstitial fluid space, the primary site of drug-microorganism interaction.