Percent osteonal bone versus osteon counts: the variable of choice for estimating age at death

Ahlqvist and Damsten's (1969) modification of the Kerley (1965) method for histological age estimation uses percent osteonal bone, rather than actual osteon counts, in order to eliminate the difficulty of distinguishing between intact and fragmentary osteons. Since their method has been developed for the femur only, and several more recent methods have been proposed that utilize percent osteonal bone, a study was undertaken to ascertain the relative value of percent osteonal bone compared with osteon counts to estimate age at death for the radius, tibia, and fibula. First the question of how much of the cross-section of a bone should be sampled was addressed by comparing the results of regression against age for percent osteonal bone derived from sampling only four fields with those derived from the entire cross-section of the radius. A significant age association was found only when the entire cross-section was sampled. In order to evaluate the relative merit of using either percent osteonal bone, or osteon counts to estimate age, each variable was regressed against age. Significant correlation coefficients were found for all three bones when the independent variable was osteon counts. When percent osteonal bone was employed, a significant correlation was found only for the radius. Stepwise linear regression found osteon counts for the fibula alone to be the best age predictor. Finally, a repeated measures analysis of variance revealed that percent osteonal bone and osteon counts both differ among the three bones within an individual. Based upon these results, osteon counts, rather than percent osteonal bone, should be the variable of choice when developing histological age predicting methods.