Engineering and Computer Science Faculty Publications

Title

Calculation of Porosity and Osteonal Cement Line Effects on The Effective Fracture Toughness of Cortical Bone In Longitudinal Crack Growth

Document Type

Article

Publication Date

9-5-2000

Journal Title

Journal of Biomedical Materials Research

Volume

51

Issue

3

First Page

504

Last Page

509

DOI

10.1002/1097-4636(20000905)51:3<504::AID-JBM27>3.0.CO;2-I

Abstract

Based on the microscopic analyses of cracks and correlational studies demonstrating evidence for a relationship between fracture toughness and microstructure of cortical bone, an equation was derived for bone fracture toughness in longitudinal crack growth, using debonding at osteonal cement lines and weakening effect of pores as main crack mechanisms. The correlation between the measured and predicted values of fracture toughness was highly significant but weak for a single optimal value of matrix to cement line fracture toughness ratio. Using fracture toughness values and histomorphometrical parameters from an available data set, matrix to cement line fracture toughness ratio was calculated for human femoral bone. Based on these calculations it is suggested that the effect of an osteon on fracture toughness will depend on the cement line's ability to compensate for the pore in an osteon. Matrix to cement line fracture toughness ratio significantly increased with increasing age, suggesting that the effectiveness of osteons in energy absorption may be reduced in the elderly due to a change in cement line properties.

Keywords

Cortical bone, fracture toughness, osteon, cement line, longitudinal crack growth