Intraskeletal Variability of The Femoral Cortex In Adult Individuals:Impact On Age-At-Death Estimation

Microscopic methods for age estimation are one of the few options left for identification when dealing with incomplete or fragmentary remains. Issues such as intra and inter-skeletal variability due to biomechanics and other intrinsic factors might have an impact on the histological techniques. Thus, further investigation is required to ensure accurate ageestimates. This study aims to explore cortical bone variability along and across the femoraldiaphysis to assess its impact on histomorphometric parameters commonly used for ageestimation.Cross-sections were obtained from the proximal, midshaft, and distal segments along femoral diaphysis from a sample of 10 individuals. Osteon population density (OPD), osteon area (On.Ar), osteon perimeter (On.Pr), and osteon circularity (On.Cr) were collected within each cross-section from four anatomical axes (anterior, posterior, medial, and lateral). Paired t-test was used to test for intra-observer error. A one-way repeated measures ANOVA was conducted to explore the histomorphometric differences along the femoral length as well as within the femoral cross-section. The femur-only formula by Goliath et al. (2016) was employed to estimate age and assess the impact of intraskeletal variability on the age estimates.Intra-observer error demonstrated agreement between observations. A statistically significant difference between OPD values along the femoral length was found. Within the cross-section, variation was not statistically significant for all four parameters. No difference between the three femoral segments was observed for the age estimated using Goliath et al.(2016).Our results suggest that cortical bone variability in terms of bone remodelling exists along the length of the femoral diaphysis. Histomorphometric techniques using OPD should consider such variation when developing aging methods. However, osteon metricparameters might be more useful to mitigate the impact of intraskeletal variation. Further research could involve a larger sample as well as other skeletal elements.