Finite element modeling of the microarchitecture of cancellous bone: Techniques and applications

Cancellous bone is a complex structure with mechanical behavior that is affected by bone tissue-level mechanical properties as well as by the shape of trabeculae, their spatial arrangement, and their level of connectivity. The increasing public health threat of osteoporosis motivates investigations of the mechanical behavior of cancellous bone with particular emphasis on characterizing its stiffness and strength as function of its tissue-level properties and microarchitectural structure. The small scale at which mechanical phenomena occur in cancellous bone (100-1000 µm) limits experimental work. Thus, finite element modeling became a superior tool for studying load-bearing phenomena at the trabecular scale. This chapter describes modeling techniques and provides examples for finite element simulations of load-bearing conditions in cancellous bone microarchitecture. After discussing some general considerations in modeling the geometry and mechanical properties of cancellous bone, the two dominant modeling approaches, micro-imaging-based modeling and generic lattice modeling, are reviewed. The single-trabecula building-block, a standard (generic) model component for largescale finite element models of cancellous bone, is employed here to study several loadbearing phenomena in normal and osteoporotic cancellous bone, including studies of the apparent compression behavior of cancellous bone, the strain inhomogeneity in individual trabeculae, and buckling behavior of trabeculae.