Biaxial yield strains in bovine tibial trabecular bone do not depend on volume fraction

摘要

Multiaxial loads occur in trabecular bone in vivo, and have been associated with fracture and implant loosening. Knowledge of the multiaxial yield properties of trabecular bone should therefore improve the prediction of bone fracture in the diagnosis of osteoporosis, the evaluation of treatment prutocols, and the design of total joint arthroplasty and fixation devices. Several studies of bovine tibial trabecular bone have found that, despite considerable heterogeneity in the uniaxial yield stresses, the uniaxial yield strains are independent of apparent density within a given anatomic site [1, 2]. This suggests that the yield properties of trabecular bone could be described using a failure criterion formulated in strain space without dependence on volume fraction or architecture. This has not been confirmed for general loading conditions, because only limited data is available for multiaxial yield properties, and these are reported primarily in terms of stress. However, a study of axialshear loading found that the yield strains did not depend on density and modulus [3]. The lack of experimental data for biaxial and triaxial compressive yield strains is primarily due to the technical difficulties of performing the experimental measurements [4]. Recent advances in computer modeling techniques have made it possible to accurately simulate the nonlinear behavior of trabecular bone for compression tension and shear loading [5]. The goal of this study was to apply this technology to determine whether the biaxial compressive yield properties of bovine tibial trabecular bone are dependent on volume fraction. Specifically, the objectives were to 1) determine the biaxial compressive yield properties of bovine tibial trabecular bone using high-resolution finite element models, and 2) determine any statistically significant correlation between the apparent yield properties and volume fraction.