Temporal and spatial activity in mirror segments of mature dog fibulae

This investigation was undertaken to determine if the metabolic activity of homotypic segments of dog fibulae could be reliably compared in a thirty day period. Activities analyzed were: cumulative formation, porosity, resorption and apposition. Analyses were performed on contiguous tissue sections using microradiographic and tetracycline techniques. Spatial arrangements of the various activities were analyzed by constructing three dimensional models. The data permitted the following conclusions: 1) The mean differences between dog homotypic fibular segments are much smaller than the mean differences between heterotypic sites. 2) The use of homotypic fibular sites as valid controls should be limited to investigations in which the differences worth detecting are at least greater than 4% (apposition), 2% (resorption), 0.6% (porosity), and 2% (cumulative formation). 3) Of the four parameters measured, porosity was the most constant, showing no significant differences between mirror segments. 4) Lag correlations emphasize the importance of utilizing all available contiguous sections in a given specimen. 5) Physiologic resorption was not exclusive in old bone. 6) The sites of metabolic activity were predominantly found among specific active osteons which were primarily distributed peripherally in a strikingly similar pattern between mirror segments.