Dependence of Yield Strain on Anatomic Site for Human Trabecular Bone

The yield strain behavior of trabecular bone has gained increased importance as evidence accumulates that remodeling and failure criteria can be expressed as a function of strain alone (Turner et al., 1997; Silva et al., 1998). These findings rely on the results of previous studies in which yield strains were found to be isotropic and generally independent of volume fraction (Turner, 1989; Kopperdahl and Keaveny, 1998; Chang et al., 1999), although relatively little work has been done to substantiate these results for human trabecular bone. Thorough consideration of the dependence of yield strain on volume fraction should include analyses of trabecular bone from different anatomic sites since site-dependent differences in trabecular architecture have been well-correlated with mechanical properties (Goulet et al., 1994). However, differences in testing protocols and in definitions of modulus and yield point (Linde, 1994) have led to discrepancies in reported yield strain values in the literature (Kopperdahl and Keaveny, 1998). This prevents inter-study comparisons of the yield strain behavior of human trabecular bone across different anatomic sites, and yet characterizing this behavior is a fundamental step both. In the validation of uniform strain adaptation models and in the development of failure criteria.