Mechanical properties of collagen from decalcified rat femur in relation to age andin vitro maturation

Abstract
Cortical bone collagen was obtained by decalcifying femoral bones from 2-,5-,15-, and 25-month-old male rats. Collagen specimens were cut longitudinal to the long axis of the femur and tested mechanically. The maximum load (ultimate strength) and maximum slope of the load-strain curve (maximum stiffness) were found to decrease with age. The age-related reduction in the mechanical parameters resulted from a change in the mechanical strength of the constituent collagen and a change in the morphology of the bone tissue.In vitro aging, produced by incubating for 0–5 months, did not change the mechanical strength of bone collagen specimens obtained from 2-month-old rats. The changes in the mechanical characteristics of bone collagen, accompanyingin vivo andin vitro aging are the opposite of those observed in soft tissue collagen. In the latter there is an increase in the mechanical strength duringin vivo andin vitro aging.