A stratified model to predict dispersion in trabecular bone

Frequency-dependent phase velocity (dispersion) has previously been measure d in trabecular bone by several groups. In contrast to most biologic tissue s, phase velocity in trabecular bone tends to decrease with frequency. A st ratified model, consisting of alternating layers of bone and marrow (in viv o) or water (in vitro), has been employed in an attempt to explain this phe nomenon. Frequency-dependent phase velocity was measured from 300 to 700 kH z in 1) phantoms consisting of regularly spaced thin parallel layers of pol ystyrene sheets in water and 2) 30 calcaneus samples in vitro. For the poly styrene phantoms, the agreement between theory and experiment was good. For the calcaneus samples, the model has some limited usefulness (uncertainty of about 5%) in predicting average phase velocity. More importantly, the mo del seems to perform consistently well for predicting the frequency depende nce of phase velocity in calcaneus.