The bending and dynamic mechanical properties of cortical bone: the effects of sodium fluoride and the relationship to physical properties

Abstract

Bone is a complex organic composite material. The graphics. interface between the mineral and organic phases of bone is significant both to medicine and to the biokinetics, a field which seeks to create advanced synthetic materials by copying natural ones. The relationship between the mechanical properties and physical properties of bone as well as the relationship between the static and dynamic properties is also important to biokinetics. Walsh et al. (1991) have developed a detergent-ion protocol that interferes with the bonding between the organic and mineral constituents of bone. The elect of this defending on equine cortical bone was investigated using dynamic mechanical analysis IDMAI in the bending mode and quasi-static three-point bending tests. Specimens of cortical bone, 56mm by 5111m by 2n1m, were prepared from equine third metacarpal bones and human femurs. Following the detergent-ion protocol of Walsh et a1., the equine bones were soaked in a non-ionic detergent for 24 hours. The treatment group was soaked in a 2 M sodium fluoride solution for 12 days. The control group was soaked in 0. 145 M sodium chloride for 12 days. The storage modulus and tan [] were monitored with DMA in the bending mode every other day. After treatment, the equine specimens were tested in three-point bending with a span of 38 mm and a strain rate of 1 mnl/min. Twenty human bone specimens were tested in DMA and then three-point bending. The wet density, porosity, and ash content were then determined. The ion treatment reduced the dynamic storage and three-point bending moduli, the yield and ultimate strengths, and ratio of yield to ultimate strength. This protocol also increased the tan 8, loss modulus, energy absorbed to failure, and percent of energy absorbed post-yield. The change in properties was generally consistent with rebinding in a fiber-matrix composite. The dynamic storage modulus correlated well to the three-point bending [] but the dynamic modulus was consistently lower. The modulus [], correlation between other static and dynamic properties was weak. For the human specimens, the elastic modulus was moderately correlated to wet density and porosity. The modulus was also correlated to wet density.