A 20-YEAR PERSPECTIVE ON THE MECHANICAL-PROPERTIES OF TRABECULAR BONE

We have reviewed highlights of the research in trabecular bone biomech anics performed over the past 20 years. Results from numerous studies have shown that trabecular bone is an extremely heterogeneous material -modulus can vary 100-fold even within the same metaphysis-with varyin g degrees of anisotropy. Strictly speaking, descriptions of the mechan ical properties of trabecular bone should therefore be accompanied by specification of factors such as anatomic site, loading direction, and age. Research efforts have also been focused on the measurement of me chanical properties for individual trabeculae, improvement of methods for mechanical testing at the continuum level, quantification of the t hree-dimensional architecture of trabecular bone, and formulation of e quations to relate the microstructural and continuum-level mechanical properties. As analysis techniques become more sophisticated, there is now evidence that factors such as anisotropy and heterogeneity of ind ividual trabeculae might also have a significant effect on the continu um-level properties, suggesting new directions for future research. Ot her areas requiring further research are the time-dependent and multia xial failure properties at the continuum level, and the stiffness and failure properties at the lamellar level. Continued research in these areas should enhance our understanding of issues such as age-related b one fracture, prosthesis loosening, and bone remodeling.