IMPLEMENTATION OF STRAIN-RATE AS A BONE REMODELING STIMULUS

Strain rate is implemented as a stimulus for surface bone remodeling. Using idealized models of trabecular bone structures, the surface remo deling predictions using the strain rate as the stimulus ave compared with the predictions using the peak strain magnitude as the stimulus. For a uniaxially loaded cruciform shape, the comparison shows that the two surface remodeling stimuli predict the same final shape under a p eriodic compressive load but the two evolutionary paths to final shape s ave different. Two biaxially loaded regular grid models of trabecula r structure were considered, one a grid of square diamond shaped eleme nts and the other a brick wall patterned grid. For both of these ideal ized trabecular structures, the comparison shows that the two surface remodeling stimuli predict the same final shape under a periodic compr essive load even from these distinctly different initial grid patterns , and the evolutionary paths to final shapes are quite different. In g eneral the two stimuli do not predict the same remodeling and the cond itions under which they do are derived. The models developed are also applied to the data from the animal experiments reported in Goldstein et al. (1991), and it is shown that the strain rate stimulus predicts bone remodeling similar to what was experimentally observed.