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The Biot and the modified Biot-Attenborough (MBA) models for acoustic wave propagation in porous media have been successfully applied to model propagation in cancellous bone. However, neither of these models allows for acoustic anisotropy because they assume cancellous bone to be isotropic. The present study was aimed at modifying the Biot and the MBA models for predicting the anisotropic phase velocities as functions of the propagation angle relative to the trabecular alignment of cancellous bone. This was done by incorporating angle-dependent parameters into the Biot and the MBA models. The predictions of both modified models were compared with those of the Schoenberg model for anisotropy in cancellous bone and with previously published in vitro measurements in bovine cancellous bone. Introducing anisotropy into the two isotropic models through the angle-dependent parameters significantly improved their ability to predict the angular dependence of the phase velocities for the fast and the slow waves in cancellous bone. While the Biot and the MBA models are able to account for many subtle effects in cancellous bone, the modified models are likely to be of greater practical use.


The Biot and the modified Biot-Attenborough (MBA) models for acoustic wave propagation in porous media have been successfully applied to model propagation in cancellous bone. However, neither of these models allows for acoustic anisotropy because they assume cancellous bone to be isotropic. The present study was aimed at modifying the Biot and the MBA models for predicting the anisotropic phase velocities as functions of the propagation angle relative to the trabecular alignment of cancellous bone. This was done by incorporating angle-dependent parameters into the Biot and the MBA models. The predictions of both modified models were compared with those of the Schoenberg model for anisotropy in cancellous bone and with previously published in vitro measurements in bovine cancellous bone. Introducing anisotropy into the two isotropic models through the angle-dependent parameters significantly improved their ability to predict the angular dependence of the phase velocities for the fast and the slow waves in cancellous bone. While the Biot and the MBA models are able to account for many subtle effects in cancellous bone, the modified models are likely to be of greater practical use.