There is a need for easily repeatable and accurate age estimation methods that produce reliable and timely results in forensic anthropology and bioarchaeology. The goal of this study was to improve upon the histological age estimation method developed by Kerley (1965) on the femur. The anterior, posterior, medial, and lateral regions of 200 cross-sections were histologically (100x magnification) examined using a checkerboard pattern composed of three columns. The number of fields read per region was determined by the thickness of the cortex because the bone was read from the periosteal border to the endosteal border. The femoral midshaft was selected because this portion of bone is easily recognizable, often recovered in forensic casework, and withstands taphonomic damages more so than other bones (Kerley, 1965).
The derived variables collected for analysis from each region included intact osteon fragment density (IOPD), osteon fragment density (FOPD), OPD, the proportion of intact osteons that comprise OPD, and relative cortical area. Results revealed positive linear relationships between FOPD and OPD for which more than 50% of the variation in each variable was explained by age. From these linear relationships, regression analysis and inverse prediction produced a total of 21age predicting equations; 95% confidence limits are presented for each individual age predicting equation. The current study provides a modification of currently established age estimation methods for the femur.