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We examined the changes in mechanical strain response of male and female mouse tibia and ulna, using axial compression tests, to assess age-related changes in tibiae and ulnae by a non-contact strain measurement technique called the digital image correlation (DIC) and the standard strain gage. A unique aspect of the study was to compare bones from the same animal to study variations in behavior with aging. This study was conducted using male and female C57Bl/6 mice at 6, 12 and 22 months of age (N=6-7 per age and sex) using three load levels. The DIC technique was able to detect a greater number of statistically significant differences in comparison to the strain gaging method. Male ulna showed significantly higher DIC strains compared to strains captured from strain gage at all three levels of load at 6 months and in the lowest load at 12 months. DIC measurements revealed that the ulna becomes stiffer with aging for both males and females, which resulted in 0.4 to 0.8 times reduced strains in the 22-month group compared to the 6 month group. Male tibia showed three-fold increased strains in the 22 months group at 11.5 N load compared to 6 months group (p

Aging is known to reduce bone quality and bone strength. We sought to determine how aging affects the biomechanical and architectural properties of various long bones, and if sex influences age related differences/changes. While researchers have extensively studied these changes in individual bones of mice, there is no comprehensive study of the changes in the bones from the same mice to study the changes with aging. We performed three point bending tests and microcomputed tomography (microCT) analysis on femurs, tibiae and ulnae. Three point bending tests were utilized to calculate biomechanical parameters and imaging was also performed using high resolution microCT to reveal both cortical and trabecular microarchitecture C57BL/6N mice were divided into three age groups: 6, 12 and 22 months. Each age and sex group consisted of 6–7 mice. The ultimate load to failure (UL), elastic stiffness (ES), modulus of elasticity (E) and the moment of inertia about bending axis (MOI) for each bone was calculated using three point bending test. MicroCT scans of all the bones were analyzed to determine cortical bone volume per tissue volume (C.BV/TV), trabecular bone volume per tissue volume (Tb.BV/TV), cortical bone area (B.Ar) using CTAn's microCT analysis and tested for correlation with the biomechanical parameters. Mean (standard error) values of UL in femur decreased from 19.8(0.6) N to 12.8(1.1) N (p, Highlights • Assess age/gender related biomechanical property changes in femur, tibiae and ulnae. • C57Bl/6 mice were divided into three age groups: 6, 12 and 22 months. • Significant decline in the biomechanical response of femurs and tibiae at the age of 22 months. • Ulnae showed some improved properties with aging. • Aging affected biomechanical rather than microCT properties and female bones