Estimation of Lacunar Permeability in Anatomical Regions of Femoral Cortex: Endocortical Versus Periosteal

Bone’s adaptation occurs in response to mechanical loads. In vivo experimental studies explained that cortical bone envelopes (periosteal and endocortical) and their anatomical regions (anterior, posterior, lateral, medial) experience differential loading-induced osteogenesis. It has always been a challenge to establish a computer model to precisely predict such non-uniform new bone formation at the cortex due to mechanobiological stimuli such as strain or canalicular fluid flow. Lacunar permeability governs canalicular fluid velocity magnitude in bone-cross section. Anatomical variations of permeability could be the reason of differential fluid flow response which causes distinct site-specific bone formation. Therefore, it is important to compute poromechanical properties which are required to compute flow distribution. Lacunar canalicular permeability of the periosteal and endosteal surfaces in different anatomical locations has not been well reported. Thus, this paper estimates the poromechanical properties of cortical bone specially the permeability at periosteal and endocortical envelopes in their different anatomical regions, i.e. medial, lateral, anterior and posterior. Nanoindentation technique in combination with poroelastic optimization technique was employed. The result indicates that the endocortical surface was found to be more permeable than periosteal surface. Moreover, medial and lateral sides were also found more permeable than the other two regions, namely anterior and posterior. A clear understanding on cortical bone permeability will help researchers to precisely simulate the site-specific osteogenesis.