Bone Mineral Assay: Its Relation to the Mechanical Strength of Cancellous Bone

Abstract

Photon absorptiometric (¹²⁵I) bone mineral assay and low strain-rate axial compression tests were carried out on cylindrical cancellous bone specimens from the proximal tibial epiphysis of large, skeletally mature mongrel dogs. Bone mineral assay was reproducible within ±5.0 per cent (99 per cent tolerance limits). Linear regression analysis with the bone mineral concentration as the independent variable showed a strong correlation towards the ultimate strength ( r = 0.92) and the yield strength ( r = 0.89), somewhat weaker towards the elastic modulus ( r = 0.82), the ultimate energy absorption ( r = 0.79), and the yield energy absorption ( r = 0.73), and insignificant towards the ultimate strain ( r = −0.14) and the yield strain ( r = −0.18). The power relationships between trabecular bone density and compressive strength and modulus suggested by Carter and Hayes (1977) were not statistically superior to linear relationships in the relatively narrow density range reported here. The quadratic relationship between bone mineral content and energy absorption suggested for cortical bone (Currey, 1969) could not be confirmed for trabecular bone. Linear regression analysis with the elastic modulus as the independent variable showed that the regression coefficients to predict ultimate strength and yield strength are statistically indistinguishable from those found in studies on human material. It is concluded that non-destructive techniques to measure bone density and mineralization may be suitable for clinical bone strength assay.