Dependence of intertrabecular permeability on flow direction and anatomic site

The structure-function relationships for the permeability of trabecular bon e may have relevance for tissue engineering, total joint replacements, and whole bone mechanics. To investigate such relationships, we used a constant flow rate permeameter to determine the intrinsic permeability of trabecula r bone specimens, oriented longitudinally or transversely to the principal trabecular orientation, from the human vertebral body (n=20), human proxima l femur (n=12), and bovine proximal tibia (n=24). Overall, the intertrabecu lar permeability ranged from 2.68x10(-11) to 2.00x10(-8) m(2). Significant negative nonlinear relations between intertrabecular permeability and volum e fraction were found for each group except the longitudinal bovine proxima l tibial specimens (r(2) = 0.34-0.80). The average permeability ratio, a me asure of the anisotropy, was 2.05, 6.60, and 23.3 for the human vertebral b ody, bovine tibia, and human femur, respectively. The permeability depended strongly on flow direction relative to the principal trabecular orientatio n (p<0.0001) and anatomic site (p<0.0001). In addition to providing a compr ehensive description of intertrabecular permeability as a function of anato mic site and flow direction, these data provide substantial insight into th e underlying structure-function relationships. (C) 1999 Biomedical Engineer ing Society. [S0090-6964(99)00704-3].